Climate Research Highlights

WashU affiliated authors: S. Saha, V. Ramani, A. Verma

Abstract: Development of cost-effective, high-performance and non-precious electrocatalyst for Polymer Electrolyte Membrane Fuel Cell (PEMFC) is an essential requirement to replace Pt-group metal catalyst. Nanostructured transition metal carbides have attracted vast interest in fuel cell and electrolyser as electrocatalyst or support, due to its high conductivity and thermo-chemical stability. This paper provides a review in the recent experimental and theoretical studies on Titanium Carbides (TiC) as electro-catalyst and support for fuel cell and electrolyser. The morphologies of TiC show strong impact on the performance of the electrocatalyst in different oxidation and reduction reactions. This study discusses the electrochemical properties and synthesis processes for the development of different TiC nanostructure. The critical issues, challenges and the future perspective for TiC as electrocatalyst as well as electrocatalyst support in fuel cell and electrolyzer with desired activity and stability are also discussed.

Citation: S. Saha, B.M. Rajbongshi, V. Ramani, A. Verma, Titanium carbide: An emerging electrocatalyst for fuel cell and electrolyser, International Journal of Hydrogen Energy, 2021, ISSN 0360-3199, https://doi.org/10.1016/j.ijhydene.2021.01.116.

WashU affiliated authors: Randall V. Martin and Erin E. McDuffie (Dept. of Energy, Environmental, and Chemical Engineering)

Abstract: Aerosols over Earth’s remote and spatially extensive ocean surfaces have important influences on planetary climate. However, these aerosols and their effects remain poorly understood, in part due to the remoteness and limited observations over these regions. In this study, we seek to understand factors that shape marine aerosol size distributions and composition in the northwest Atlantic Ocean region. We use the GEOS-Chem model with the TwO-Moment Aerosol Sectional (TOMAS) microphysics algorithm model to interpret measurements collected from ship and aircraft during the four seasonal campaigns of the North Atlantic Aerosols and Marine Ecosystems Study (NAAMES) conducted between 2015 and 2018. Observations from the NAAMES campaigns show enhancements in the campaign-median number of aerosols with diameters larger than 3 nm in the lower troposphere (below 6 km), most pronounced during the phytoplankton bloom maxima (May/June) below 2 km in the free troposphere. Our simulations, combined with NAAMES ship and aircraft measurements, suggest several key factors that contribute to aerosol number and size in the northwest Atlantic lower troposphere, with significant regional-mean (40–60∘ N and 20–50∘ W) cloud-albedo aerosol indirect effect (AIE) and direct radiative effect (DRE) processes during the phytoplankton bloom. These key factors and their associated simulated radiative effects in the region include the following: (1) particle formation near and above the marine boundary layer (MBL) top (AIE: −3.37 W m−2, DRE: −0.62 W m−2); (2) particle growth due to marine secondary organic aerosol (MSOA) as the nascent particles subside into the MBL, enabling them to become cloud-condensation-nuclei-sized particles (AIE: −2.27 W m−2, DRE: −0.10 W m−2); (3) particle formation and growth due to the products of dimethyl sulfide, above and within the MBL (−1.29 W m−2, DRE: −0.06 W m−2); (4) ship emissions (AIE: −0.62 W m−2, DRE: −0.05 W m−2); and (5) primary sea spray emissions (AIE: +0.04 W m−2, DRE: −0.79 W m−2). Our results suggest that a synergy of particle formation in the lower troposphere (particularly near and above the MBL top) and growth by MSOA contributes strongly to cloud-condensation-nuclei-sized particles with significant regional radiative effects in the northwest Atlantic. To gain confidence in radiative effect magnitudes, future work is needed to understand (1) the sources and temperature dependence of condensable marine vapors forming MSOA, (2) primary sea spray emissions, and (3) the species that can form new particles in the lower troposphere and grow these particles as they descend into the marine boundary layer.

Citation: Croft, B., Martin, R. V., Moore, R. H., Ziemba, L. D., Crosbie, E. C., Liu, H., Russell, L. M., Saliba, G., Wisthaler, A., Müller, M., Schiller, A., Galí, M., Chang, R. Y.-W., McDuffie, E. E., Bilsback, K. R., and Pierce, J. R.: Factors controlling marine aerosol size distributions and their climate effects over the northwest Atlantic Ocean region, Atmos. Chem. Phys., 21, 1889–1916, https://doi.org/10.5194/acp-21-1889-2021, 2021.

WashU affiliated authors: Edited by Joan E. Strassmann (Dept. of Biology)

Abstract: Through the secretion of “public goods” molecules, microbes cooperatively exploit their habitat. This is known as a major driver of the functioning of microbial communities, including in human disease. Understanding why microbial species cooperate is therefore crucial to achieve successful microbial community management, such as microbiome manipulation. A leading explanation is that of Hamilton’s inclusive-fitness framework. A cooperator can indirectly transmit its genes by helping the reproduction of an individual carrying similar genes. Therefore, all else being equal, as relatedness among individuals increases, so should cooperation. However, the predictive power of relatedness, particularly in microbes, is surrounded by controversy. Using phylogenetic comparative analyses across the full diversity of the human gut microbiota and six forms of cooperation, we find that relatedness is predictive of the cooperative gene content evolution in gut-microbe genomes. Hence, relatedness is predictive of cooperation over broad microbial taxonomic levels that encompass variation in other life-history and ecology details. This supports the generality of Hamilton’s central insights and the relevance of relatedness as a key parameter of interest to advance microbial predictive and engineering science.

DOI: https://doi.org/10.1073/pnas.2016046118

WashU affiliated authors: Hannah Padda (Brown School)

Abstract: Landscape change is one of the foremost drivers of the emergence of infectious diseases. Exploring demographic, household and environmental conditions under which infectious diseases occur may inform strategies to prevent disease emergence in human populations. We collected blood samples from 523 humans and explore factors for arbovirus emergence in Bahia, Brazil. The overall arbovirus seroprevalence was 65.2%, with the genus Flavivirus most prevalent (64.4%). Based on monotypic reactions, the population had contact with five arbovirus: Dengue 3, Ilheus, Oropouche, Caraparu and Eastern equine encephalitis virus. To our knowledge, this is the first study reporting exposure to Oropouche, Caraparu and Eastern equine encephalitis virus in human populations in Bahia, Northeast of Brazil. The best model fit demonstrated that household and environmental variables were more predictive of the risk of arbovirus exposure than demographic variables. The presence of forest and free‐living monkeys in the areas close to the communities had a protective effect for the human population (i.e. lower seroprevalence). The dilution effect is considered as one explanation for this finding. These results highlight the important ecological role of wildlife‐friendly agriculture.

Citation: Catenacci, LS, Ferreira, MS, Fernandes, D, et al. Individual, household and environmental factors associated with arboviruses in rural human populations, Brazil. Zoonoses Public Health. 2021; 00: 1– 10. https://doi.org/10.1111/zph.12811

WashU affiliated authors: Caitlyn. G. Rankin (Dept. of Anthropology)

Abstract: Narratives of ecocide, when a society fails due to self‐inflicted ecologic disaster, have been broadly applied to many major archaeological sites based on the expected environmental consequences of known land‐use practices of people in the past. Ecocide narratives often become accepted in a discourse, despite a lack of direct evidence that the hypothesized environmental consequences of land‐use practices occurred. Cahokia Mounds, located in a floodplain of the central Mississippi River Valley, is one such major archaeological site where untested narratives of ecocide have persisted. The wood‐overuse hypothesis suggests that tree clearance in the uplands surrounding Cahokia led to erosion, causing increasingly frequent and unpredictable floods of the local creek drainages in the floodplain where Cahokia Mounds was constructed. Recent archaeological excavations conducted around a Mississippian Period (AD 1050–1400) of earthen mound in the Cahokia Creek floodplain shows that the Ab horizon on which the mound was constructed remained stable until industrial development. The presence of a stable ground surface (Ab horizon) from Mississippian occupation to the mid‐1800s does not support the expectations of the wood‐overuse hypothesis. Ultimately, this research demonstrates that pre‐Colombian ecological change does not inherently cause geomorphic change, and narratives of ecocide related to geomorphic change need to be validated with the stratigraphic record.

Citation: Rankin, C. G., Barrier, C. R., & Horsley, T. J. (2021). Evaluating narratives of ecocide with the stratigraphic record at Cahokia Mounds State Historic Site, Illinois, USA. Geoarchaeology, 1– 19. https://doi.org/10.1002/gea.21848

WashU affiliated authors: Benjamin M. Kumfer (Dept. of Energy, Environmental, and Chemical Engineering)

Abstract: Oxy-combustion is an effective carbon capture technology. Many oxy-combustion technologies utilize recycled flue gas (RFG) for dilution to control temperature and heat flux. As the concentration of dilution gas on the fuel and oxidant side changes, stoichiometric mixture fraction (Zst) and flame temperature will change and significantly impact the flame structure and soot formation characteristics. In this work, the effects of stoichiometric mixture fraction and flame temperature on soot formation characteristics in laminar diffusion flames are studied by diluting the fuel and changing the oxygen concentration. CO2 is used as a dilution gas to simulate the RFG in oxy-combustion. The numerical calculation combines gas reaction kinetics with a soot formation model. Soot nucleation, surface growth, oxidation processes are considered, as well as the distributions of temperature, soot concentration, and key substances. The experimental flame appearances and spectral radiation data are imaged by a hyperspectral imager, and the temperature and soot concentration are reconstructed. The results of experimental measurement and numerical calculation are compared to evaluate the applicability of the soot formation mechanism to oxy-combustion with elevated Zst and using CO2 as diluent. As the Zst increases, the flame changes into a blue flame, soot concentration and temperature in flames decrease, because nucleation and surface growth are both inhibited and oxidation is enhanced. As the flame temperature increases, the flame becomes brighter, numerical results indicate that soot formation and oxidation are both enhanced, while the promoting effect of temperature increase on surface growth is stronger than that of oxidation, resulting in an increase in soot concentration. This study provides a fundamental understanding of the effects of RFG utilization (fuel dilution and oxygen enhancement) on flame structure, temperature distribution, soot concentration and formation characteristics in non-premixed oxy-combustion systems.

DOI: https://doi.org/10.1016/j.combustflame.2021.01.018

WashU affiliated authors: Derek Hoeferlin (Dept. of Architecture)

Abstract: Designers have a three-part responsibility owed to their object of study: to appreciate, to speculate, and to collaborate. This is particularly true for the professional engagement with spaces on the scale of river basins which impact and prioritize certain design decisions on a whole different level. Adequate responses to the ongoing transformations brought forward by large-scale anthropogenic stressors across entire river systems cannot continue to be dominated with hardline and static interventions. Rather, there is a need for alternative outsets, one that begins to design with adaptive and dynamic negotiations. By looking at the example of the Mississippi River Basin, this essay proposes a new integrated water-based design methodology titled “Way Beyond Bigness: The Need for a Watershed Architecture,” an interdisciplinary strategy to rethink the management of river systems for a sustainable future.

Citation: Hoeferlin D. The Watershed Architecture of the Mississippi River Basin. The Anthropocene Review. January 2021. doi:10.1177/2053019621989080

WashU affiliated authors: Claire F. Fortenberry, Brent J. Williams, Michael J. Walker, Audrey Dang, (Dept. of Energy, Environmental and Chemical Engineering)

Abstract: Reactive oxygen species (ROS) are an important contributor to adverse health effects associated with ambient air pollution. Despite infiltration of ROS from outdoors, and possible indoor sources (eg, combustion), there are limited data available on indoor ROS. In this study, part of the second phase of Air Composition and Reactivity from Outdoor aNd Indoor Mixing campaign (ACRONIM‐2), we constructed and deployed an online, continuous, system to measure extracellular gas‐ and particle‐phase ROS during summer in an unoccupied residence in St. Louis, MO, USA. Over a period of one week, we observed that the non‐denuded outdoor ROS (representing particle‐phase ROS and some gas‐phase ROS) concentration ranged from 1 to 4 nmol/m3 (as H2O2). Outdoor concentrations were highest in the afternoon, coincident with peak photochemistry periods. The indoor concentrations of particle‐phase ROS were nearly equal to outdoor concentrations, regardless of window‐opening status or air exchange rates. The indoor/outdoor ratio of non‐denuded ROS (I/OROS) was significantly less than 1 with windows open and even lower with windows closed. Combined, these observations suggest that gas‐phase ROS are efficiently removed by interior building surfaces and that there may be an indoor source of particle‐phase ROS.

Citation: Eftekhari, A., Fortenberry, C.F., Williams, B.J., Walker, M.J., Dang, A., Pfaff, A., Ercal, N. and Morrison, G.C. (2021), Continuous measurement of reactive oxygen species inside and outside of a residential house during summer. Indoor Air. https://doi.org/10.1111/ina.12789

WashU affiliated authors: Guangjie Zheng, Yang Wang, Jian Wang (Dept. of Energy, Environmental and Chemical Engineering)

Abstract: Marine low clouds play an important role in the climate system, and their properties are sensitive to cloud condensation nuclei concentrations. While new particle formation represents a major source of cloud condensation nuclei globally, the prevailing view is that new particle formation rarely occurs in remote marine boundary layer over open oceans. Here we present evidence of the regular and frequent occurrence of new particle formation in the upper part of remote marine boundary layer following cold front passages. The new particle formation is facilitated by a combination of efficient removal of existing particles by precipitation, cold air temperatures, vertical transport of reactive gases from the ocean surface, and high actinic fluxes in a broken cloud field. The newly formed particles subsequently grow and contribute substantially to cloud condensation nuclei in the remote marine boundary layer and thereby impact marine low clouds.

Citation: Zheng, G., Wang, Y., Wood, R. et al. New particle formation in the remote marine boundary layer. Nat Commun 12, 527 (2021). https://doi.org/10.1038/s41467-020-20773-1.

WashU affiliated authors: Xinyi Liu (Dept. of Anthropology)

Abstract: It is commonly recognised that farming activities initiated independently in different parts of the world between approximately 12,000 and 8,000 years ago. Two of such agricultural centres is situated in modern-day China, where systems based on the cultivation of plants and animal husbandry has developed. Recent investigations have shown that between 5000 and 1500 cal. BCE, the Eurasian and African landmass underpinned a continental-scale process of food “globalisation of staple crops. In the narrative of food domestication and global food dispersal processes, China has played a particularly important role, contributing key staple food domesticates such as rice, broomcorn, and foxtail millet. The millets dispersed from China across Eurasia during the Bronze Age, becoming an essential food for many ancient communities. In counterpoise, southwest Asian crops, such as wheat or barley, found new habitats among the ancient populations of China, dramatically changing the course of its development. The processes of plant domestication and prehistoric agriculture in China have been a topic of extensive research, review, and discussion by many scholars around the world, and there is a great deal of literature on these topics. One of the consequences of these discoveries concerning the origins of agriculture in China has been to undermine the notion of a single centre of origin for civilisation, agriculture, and urbanism, which was a popular and widespread narrative in the past. It has become clear that agricultural centres of development in China were concurrent with, rather than after, the Fertile Crescent.

DOI:https://doi.org/10.1093/acrefore/9780199389414.013.168

WashU affiliated authors: Tristram R. Kidder (Dept. of Anthropology)

Abstract: Archaeologists and palaeoclimatologists have focused on the impact of climate on the prehistoric civilizations around the world; however, social resilience in the face of the climate change remains unclear, especially during the Neolithic and Bronze Age in the Central Plains of China (CPC). In this paper, we present palynological results from the Dahecun Core, Henan Province, China. Our pollen data indicate a warm and wet climate condition from 9200 to 4000 cal BP, which then switches to a cool and dry climatic condition during the Neolithic-Bronze Age transition (~4000–3700 cal BP). We analyze 14C dates from archaeological sites to demonstrate four episodes of population increase and present vegetation dynamics, determined from available pollen data, to provide evidence for the synchronous shifts in vegetation and human population during the Neolithic. Our results indicate that the aridification in the early Bronze Age did not cause population collapse, highlighting the importance of social resilience to climate change. The pollen, radiocarbon dates and archaeobotanical records from the CPC provides new evidence that supports the claim that the development of agriculture and complex societies, under the stress of a dry climate, set the stage for the dramatic increase of human population around 3900–3500 cal BP.

DOI:https://doi.org/10.1088/1748-9326/abdf0a

WashU affiliated authors: Moshan Chen, Carter A. Rholl, Tianchen He, Aditi Sharma, and Kimberly M. Parker (Dept. of Energy, Environmental and Chemical Engineering)

Abstract: In hydraulic fracturing fluids, the oxidant persulfate is used to generate sulfate radical to break down polymer-based gels. However, sulfate radical may be scavenged by high concentrations of halides in hydraulic fracturing fluids, producing halogen radicals (e.g., Cl•, Cl2•–, Br•, Br2•–, and BrCl•–). In this study, we investigated how halogen radicals alter the mechanisms and kinetics of the degradation of organic chemicals in hydraulic fracturing fluids. Using a radical scavenger (i.e., isopropanol), we determined that halogenated products of additives such as cinnamaldehyde (i.e., α-chlorocinnamaldehyde and α-bromocinnamaldehyde) and citrate (i.e., trihalomethanes) were generated via a pathway involving halogen radicals. We next investigated the impact of halogen radicals on cinnamaldehyde degradation rates. The conversion of sulfate radicals to halogen radicals may result in selective degradation of organic compounds. Surprisingly, we found that the addition of halides to convert sulfate radicals to halogen radicals did not result in selective degradation of cinnamaldehyde over other compounds (i.e., benzoate and guar), which may challenge the application of radical selectivity experiments to more complex molecules. Overall, we find that halogen radicals, known to react in advanced oxidative treatment and sunlight photochemistry, also contribute to the unintended degradation and halogenation of additives in hydraulic fracturing fluids.

Citation: Halogen Radicals Contribute to the Halogenation and Degradation of Chemical Additives Used in Hydraulic Fracturing, Moshan Chen, Carter A. Rholl, Tianchen He, Aditi Sharma, and Kimberly M. Parker, Environmental Science & Technology Article ASAP DOI: 10.1021/acs.est.0c03685.

WashU affiliated authors: Erin E. McDuffie (Dept. of Energy, Environmental and Chemical Engineering)

Abstract: Formaldehyde (HCHO) is generated from direct urban emission sources and secondary production from the photochemical reactions of urban smog. HCHO is linked to tropospheric ozone formation, and contributes to the photochemical reactions of other components of urban smog. In this study pollution plume intercepts during the Wintertime INvestigation of Transport, Emissions, and Reactivity (WINTER) campaign were used to investigate and characterize the formation of HCHO in relation to several anthropogenic tracers. Analysis of aircraft intercepts combined with detailed chemical box modeling downwind of several cities suggest that the most important contribution to observed HCHO was primary emission. A box model analysis of a single plume suggested that secondary sources contribute 21±10% of observed HCHO. Ratios of HCHO/CO observed in the northeast U.S., from Ohio to New York, ranging from 0.2‐0.6%, are consistent with direct emissions combined with at most modest photochemical production. Analysis of the nocturnal boundary layer and residual layer from repeated vertical profiling over urban influenced areas indicate a direct HCHO emission flux of 1.3 x 1014 molecules cm‐2 h‐1. In a case study in Atlanta, GA, nighttime HCHO exhibited a ratio to CO (0.6 – 1.8%) and was anti‐correlated with O3. Observations were consistent with mixing between direct HCHO emissions in urban air masses with those influenced by more rapid HCHO photochemical production. The HCHO/CO emissions ratios determined from the measured data are 2.3 ‐ 15 times greater than the NEI 2017 emissions database. The largest observed HCHO/CO was 1.7 – 1.8%, located near co‐generating power stations.

DOI:https://doi.org/10.1029/2020JD033518

WashU affiliated authors: Christine C Ekenga (Brown School)

Abstract: 

Background: Nature experiences have been shown to promote physical, emotional, mental and overall health. However, low-income youth often face inequities in access to nature. The purpose of this study was to evaluate the impact of a 15-week nature-based education (NBE) intervention on health-related quality of life (HRQoL) of low-income youth.

Methods: A total of 362 low-income youth (ages 9–15) in St. Louis, MO, USA, participated in this study. Study participants completed a pre- and post-intervention survey that included validated measures of six HRQoL domains (Physical Activity, Emotional Health Functioning, School Functioning, Social Functioning, Family Functioning and overall HRQoL). Random effects analysis of covariance was used to test for significant differences in HRQoL scores between the intervention and control groups, after adjusting for school, age, previous nature exposure, and Science, Technology, Engineering and Mathematics capacity.

Results: After the intervention period, youth in the NBE intervention group experienced improvements in all HRQoL domain scores (P < 0.001), whereas youth in the control group experienced declines in HRQoL domain scores (P < 0.001).

Conclusions: NBE may have a positive impact on the HRQoL of low-income youth. Further investigations examining the influence of nature-based activities on youth health outcomes are warranted.

Citation: Nadav L Sprague, Christine C Ekenga, The impact of nature-based education on health-related quality of life among low-income youth: results from an intervention study, Journal of Public Health, 2021;, fdaa243, https://doi.org/10.1093/pubmed/fdaa243

WashU affiliated authors: Jonathan A. Myers (Dept. of Biology)

Abstract: ForestGEO is a network of scientists and long-term forest dynamics plots (FDPs) spanning the Earth’s major forest types. ForestGEO’s mission is to advance understanding of the diversity and dynamics of forests and to strengthen global capacity for forest science research. ForestGEO is unique among forest plot networks in its large-scale plot dimensions, censusing of all stems ≥1 cm in diameter, inclusion of tropical, temperate and boreal forests, and investigation of additional biotic (e.g., arthropods) and abiotic (e.g., soils) drivers, which together provide a holistic view of forest functioning. The 71 FDPs in 27 countries include approximately 7.33 million living trees and about 12,000 species, representing 20% of the world’s known tree diversity. With >1300 published papers, ForestGEO researchers have made significant contributions in two fundamental areas: species coexistence and diversity, and ecosystem functioning. Specifically, defining the major biotic and abiotic controls on the distribution and coexistence of species and functional types and on variation in species’ demography has led to improved understanding of how the multiple dimensions of forest diversity are structured across space and time and how this diversity relates to the processes controlling the role of forests in the Earth system. Nevertheless, knowledge gaps remain that impede our ability to predict how forest diversity and function will respond to climate change and other stressors. Meeting these global research challenges requires major advances in standardizing taxonomy of tropical species, resolving the main drivers of forest dynamics, and integrating plot-based ground and remote sensing observations to scale up estimates of forest diversity and function, coupled with improved predictive models. However, they cannot be met without greater financial commitment to sustain the long-term research of ForestGEO and other forest plot networks, greatly expanded scientific capacity across the world’s forested nations, and increased collaboration and integration among research networks and disciplines addressing forest science.

DOI: https://doi.org/10.1016/j.biocon.2020.108907

WashU affiliated authors: Ziyad Al-Aly (Dept. of Medicine, Institute of Public Health)

DOI:https://doi.org/10.1681/ASN.2020121713

WashU affiliated authors: Hamed Gholami Derami (Dept. of Mechanical Engineering and Materials Science)

Abstract: Polydopamine (PDA), a synthetic and organic material, has emerged as a promising material platform for various applications in energy, environmental, and biomedical fields. PDA, formed by self-polymerization of dopamine, is rich in catechol and amine groups, which facilitate covalent conjugation and/or other non-covalent interactions with organic and inorganic materials. It is highly biocompatible, biodegradable, has broadband light absorption spectrum and excellent light-to-heat conversion efficiency. Also, it is easy to synthesize and functionalize. The combination of excellent characteristics of polydopamine-based nanomaterials, make them a promising adsorbent agent for environmental wastewater treatment and photothermal agent for biomedical applications.
In the first half of thesis, we utilize the surface chemical functionality of polydopamine nanoparticles and their affinity to heavy metal ions and organic dyes to realize multifunctional filtration membranes that remove heavy metal ions and organic dyes from water through adsorption and catalytic degradation. Polydopamine exhibits high adsorption capacity toward heavy metal ions and organic dyes. Adsorption-based membrane technologies can be ideal for continuous flow water purification and have been extensively employed at industrial scale for water reclamation. By introducing polydopamine nanoparticles during bacteria-mediated cellulose growth, we fabricated a composite foam and membrane to study the adsorption behavior of the nanocomposites in different environmentally relevant pH and concentrations. The PDA/BNC membrane was used to investigate the removal efficiency of toxic heavy metals ions such as Pb (II) and Cd (II) and organic pollutants such as rhodamine 6G and methylene blue. Furthermore, to improve the range of pH in which the composite membrane is effective for dye removal, we fabricated another novel polydopamine/nanocellulose membrane, which is decorated with palladium (Pd) nanoparticles to remove organic dyes from contaminated water through catalytic dye degradation.
In the second part of thesis, we develop polydopamine-based nanomaterials and experimental setups to be used in biomedical applications such as drug delivery and photothermal stimulation of cells. Using mesoporous silica-coated PDA nanoparticles as drug carrier and tetradecanol (TD) as gate keeper, we demonstrated that we could enhance the immune system response toward Melanoma cancer in mouse model through combination of photothermal and immunotherapy. Polydopamine core works as a photothermal agent to cause localized release of gardiquimod and tumor cell death upon NIR laser irradiation, hence, release of tumor associated antigens. Antigen presenting cells (APCs) including the dendritic cells and macrophages uptake these antigens and be activated around tumor site in response to these signals. Furthermore, these activated APCs, present the antigen to CD8+ cytotoxic T cells to actuate anti-tumor immune response. We have shown that this treatment is effective in reducing the tumor size and eliminating it in majority of cases. Also, the treatment created a memory effect in immune system toward melanoma cancer when second cancer event happened in mice that were treated before.
Finally, we investigated the possibility of controlling the excitable cells’ activity through nanoheating. This was made possible by using polydopamine nanoparticles to localize the heat on cell membrane. We demonstrated that by using polydopamine nanoparticle and polydopamine/collagen 3D foam, and by applying NIR laser light, we can reversibly modulate the activity of in vitro cultured neurons and cardiomyocytes. A reduction in firing rate of neurons and an increase in beating rate of cardiomyocytes with different degree of inhibition and excitation was observed. Effect of different parameters on the quality of modulation was investigated.

Link to dissertation:https://search.proquest.com/openview/010a9803139143c30f870f73d38d20f7/1?pq-origsite=gscholar&cbl=18750&diss=y

WashU affiliated authors: Huang Zhang, Hao Zhou, Pratim Biswas (Dept. of Energy, Environmental and Chemical Engineering)

Abstract: Gas-phase routes have emerged as a promising method for synthesizing functional nanomaterials. A review of the state-of-the-art on aerosol reactors, such as flame aerosol reactors, plasma aerosol reactors, furnace aerosol reactors, and chemical vapor deposition used for gas-phase synthesis is discussed. This is followed by a discussion of applications of gas-phase synthesized nanomaterials in photocatalysis, photovoltaics, and energy storage. A description of modeling approaches to predict and elucidate the physical and chemical processes in aerosol reactors is discussed. Multiscale modeling methods from the atomic to molecular scale, to primary particles and clusters, to larger aggregates are elucidated. Aerosol dynamics simulation for predicting the size distribution of both single- and multicomponent particles is systematically examined. Further, high-flow differential mobility analyzers used for characterizing sub 2 nm particles are discussed, along with an in situ laser diagnostic approach for measuring physical and chemical properties of as-formed particles. Finally, remarks of future trends are directed for gas-phase synthesis routines in producing energy nanomaterials.

Citation: Energy Fuels 2021, 35, 1, 63–85 Publication Date:December 21, 2020 https://doi.org/10.1021/acs.energyfuels.0c03264

WashU affiliated authors: Jacob McNeill, Crystal L. Weagle, Brenna Walsh, Randall V. Martin (Dept. of Energy, Environmental and Chemical Engineering)

Abstract: Globally consistent measurements of airborne metal concentrations in fine particulate matter (PM2.5) are important for understanding potential health impacts, prioritizing air pollution mitigation strategies, and enabling global chemical transport model development. PM2.5 filter samples (N ~ 800 from 19 locations) collected from a globally distributed surface particulate matter sampling network (SPARTAN) between January 2013 and April 2019 were analyzed for particulate mass and trace metals content. Metal concentrations exhibited pronounced spatial variation, primarily driven by anthropogenic activities. PM2.5 levels of lead, arsenic, chromium, and zinc were significantly enriched at some locations by factors of 100–3000 compared to crustal concentrations. Levels of metals in PM2.5 and PM10 exceeded health guidelines at multiple sites. For example, Dhaka and Kanpur sites exceeded the US National Ambient Air 3-month Quality Standard for lead (150 ng m−3). Kanpur, Hanoi, Beijing and Dhaka sites had annual mean arsenic concentrations that approached or exceeded the World Health Organization’s risk level for arsenic (6.6 ng m−3). The high concentrations of several potentially harmful metals in densely populated cites worldwide motivates expanded measurements and analyses.

Citation: McNeill, J., Snider, G., Weagle, C.L. et al. Large global variations in measured airborne metal concentrations driven by anthropogenic sources. Sci Rep 10, 21817 (2020). https://doi.org/10.1038/s41598-020-78789-y.

WashU affiliated authors: Steven Hartman (Institute of Materials Science and Engineering), Rohan Mishra (Dept. of Mechanical Engineering and Materials Science)

Abstract: The fluoride ion is well suited to be the active species of rechargeable batteries, due to its small size, light weight, and high electronegativity. While existing F-ion batteries based on conversion chemistry suffer from rapid electrode degradation with cycling, those based on fluoride intercalation are currently less attractive then cation intercalation battery chemistries due to their low reversible energy densities. Here, using first-principles density-functional-theory calculations, we predict that layered electrides, such as Ca2N and Y2C – that have an electron occupying a lattice site – are promising hosts for fluoride intercalation, since their anionic electrons create large interstices. Our calculations indicate that anodes made from layered electrides can offer voltage up to −2.86 V vs. La2CoO4 cathode, capacity >250 mA h g−1, and fast diffusion kinetics with migration barriers as low as 0.15 eV. These metrics compare favorably to popular Li-ion intercalation cathodes such as LiCoO2. Electrides open up a new space for designing fluorine intercalation batteries with good performance and cyclability.

Citation:J. Mater. Chem. A, 2020,8, 24469-24476. https://doi.org/10.1039/D0TA06162J.

WashU affiliated authors: Krista M. Milich, Kayce Sorbello, Lev Kolinski, 

Abstract: Negative interactions between humans and wildlife create one of the greatest threats to biodiversity conservation. When wild animals damage the crops in agricultural fields, subsistence farmers suffer food insecurity and economic instability. Animals can be killed or injured during these interactions, and communities may develop negative feelings about conservation. To address conservation concerns, projects should look at both sides of these interactions. A Participatory Action Research approach allows researchers and community members to work collaboratively to investigate and take action in response to this issue. Our team developed a community project to determine residents’ perceptions of the benefits and costs of living around Kibale National Park, Uganda, and to implement changes to mitigate those costs. During our initial survey in 2015, we found that over 80% of our 114 respondents were subsistence farmers with no other source of income. All respondents felt that crop damage by wild animals was the biggest problem with living near the park, and they had negative feelings about the park and animals. Thus, we worked with project participants to establish the following land‐use changes throughout 2016 and 2017: (a) planting garlic as a cash crop, (b) planting tea as a buffer crop, (c) building beehive fences, and (d) maintaining a trench around the boundary of the park. Through monthly surveys, we assessed the success of these changes on reducing crop damage and improving conservation initiatives. Compliance with land‐use changes was significantly associated with a reduction in the events of crop damage, which has implications for economic stability and an individual’s attitude about conservation. This project provides guidelines for using Participatory Action Research methods to develop sustainable interventions to improve human‐wildlife interactions.

Citation: Milich KM, Sorbello K, Kolinski L, Busobozi R, Kugonza M. Case study of participatory action research for wildlife conservation. Conservation Science and Practice. 2020;e347. https://doi.org/10.1111/csp2.347

WashU affiliated authors: Tamsen Reed, Christine C. Ekenga (Brown School) 

Abstract: In the Midwestern United States (US), river flooding is a climate change-related hazard that poses a significant threat to health, well-being and economic stability. The 2019 Midwest floods led to major flooding at every monitoring site along the Mississippi River, set record water levels at 42 sites, and resulted in an estimated $6.2 billion in infrastructure damage and recovery costs. Although the risks associated with increasing flooding in the Midwestern US have been well recognized, less is known about the adaptation challenges and opportunities in the region, particularly in the Upper Mississippi River Basin. This exploratory study examined stakeholder perspectives on river system management, flood risk reduction, and adaptation planning in the Upper Mississippi River Basin. We conducted in-depth interviews with flood management stakeholders between August and October 2019. Interview data were analyzed using thematic analysis. Five themes emerged from the interviews: (1) River flooding in the Midwestern US is a different experience than US coastal flooding; (2) River flooding in the Midwestern US is a regional experience that requires a regional response; (3) Local actors face constrained resources for flood risk protection and recovery; (4) Differentiated responsibility across levels of governments makes recovery and response difficult to navigate; and (5) Competing stakeholder goals challenge cooperative flood hazard management. Overall, these results suggest that locally focused adaptation efforts, while perhaps appropriate for coastal communities or more urban contexts, are suboptimal strategies for communities in the flood-prone river basins of the Midwestern US. Instead, structures and support for regional collaboration should be considered and pursued.

Citation: Reed, Tamsen, Lisa Reyes Mason, and Christine C. Ekenga. “Adapting to Climate Change in the Upper Mississippi River Basin: Exploring Stakeholder Perspectives on River System Management and Flood Risk Reduction.” Environmental Health Insights 14 (2020), https://journals.sagepub.com/doi/10.1177/1178630220984153

WashU affiliated authors: Xiaohong Xie, Cheng He, Vijay Ramani (Dept. of Energy, Environmental and Chemical Engineering)

Abstract: The development of catalysts free of platinum-group metals and with both a high activity and durability for the oxygen reduction reaction in proton exchange membrane fuel cells is a grand challenge. Here we report an atomically dispersed Co and N co-doped carbon (Co–N–C) catalyst with a high catalytic oxygen reduction reaction activity comparable to that of a similarly synthesized Fe–N–C catalyst but with a four-time enhanced durability. The Co–N–C catalyst achieved a current density of 0.022 A cm−2 at 0.9 ViR-free (internal resistance-compensated voltage) and peak power density of 0.64 W cm−2 in 1.0 bar H2/O2 fuel cells, higher than that of non-iron platinum-group-metal-free catalysts reported in the literature. Importantly, we identified two main degradation mechanisms for metal (M)–N–C catalysts: catalyst oxidation by radicals and active-site demetallation. The enhanced durability of Co–N–C relative to Fe–N–C is attributed to the lower activity of Co ions for Fenton reactions that produce radicals from the main oxygen reduction reaction by-product, H2O2, and the significantly enhanced resistance to demetallation of Co–N–C.

Citation: Xie, X., He, C., Li, B. et al. Performance enhancement and degradation mechanism identification of a single-atom Co–N–C catalyst for proton exchange membrane fuel cells. Nat Catal 3, 1044–1054 (2020). https://doi.org/10.1038/s41929-020-00546-1

WashU affiliated authors: Amanda Koltz (Dept. of Biology)

Abstract: Human activities are transforming grassland biomass via changing climate, elemental nutrients, and herbivory. Theory predicts that food-limited herbivores will consume any additional biomass stimulated by nutrient inputs (‘consumer-controlled’). Alternatively, nutrient supply is predicted to increase biomass where herbivores alter community composition or are limited by factors other than food (‘resource-controlled’). Using an experiment replicated in 58 grasslands spanning six continents, we show that nutrient addition and vertebrate herbivore exclusion each caused sustained increases in aboveground live biomass over a decade, but consumer control was weak. However, at sites with high vertebrate grazing intensity or domestic livestock, herbivores consumed the additional fertilization-induced biomass, supporting the consumer-controlled prediction. Herbivores most effectively reduced the additional live biomass at sites with low precipitation or high ambient soil nitrogen. Overall, these experimental results suggest that grassland biomass will outstrip wild herbivore control as human activities increase elemental nutrient supply, with widespread consequences for grazing and fire risk.

Citation: Borer, E.T., Harpole, W.S., Adler, P.B. et al. Nutrients cause grassland biomass to outpace herbivory. Nat Commun 11, 6036 (2020). https://doi.org/10.1038/s41467-020-19870-y

WashU affiliated authors:  Xianda Gong (Dept. of  Energy, Environmental and Chemical Engineering)

Abstract: Ice nucleating particles (INPs) initiate the primary ice formation in clouds at temperatures above ca. −38° C and have an impact on precipitation formation, cloud optical properties and cloud persistence. Despite their roles in both weather and climate, INPs are not well characterized, especially in remote regions such as the Arctic. We present results from a ship-based campaign to the European Arctic in May to July 2017. We deployed a filter sampler and a continuous flow diffusion chamber for off- and online INP analysis, respectively. We also investigated the ice nucleation properties of samples from different environmental compartments, i.e., the sea surface microlayer (SML), the bulk seawater (BSW), and fog water. Concentrations of INP (NINP) in the air vary between two to three orders of magnitudes at any particular temperature and are, except for the temperatures above −10° C and below −32° C, lower than in mid-latitudes. In these temperature ranges INP concentrations are the same or even higher than in the mid-latitudes. Heating of the filter samples to 95° C for 1 hour we found a significant reduction in ice nucleation activity, i.e., indications that the INPs active at warmer temperatures are biogenic. At colder temperatures the INP population was likely dominated by mineral dust. The SML was found to be enriched in INP compared to the BSW in almost all samples. The enrichment factor (EF) varied mostly between 1 and 10, but EFs as high as 94.97 were also observed. Filtration of the seawater samples with 0.2 µm syringe filters lead to a significant reduction in ice activity, indicating the INPs are larger, and/or are associated with particles larger than 0.2 µm. A closure study showed that aerosolization of SML and/or seawater alone cannot explain the observed air-borne NINP unless significant enrichment of INP by a factor of 105 takes place during the transfer from the ocean surface to the atmosphere. In the fog water samples with −3.47° C we observed the highest freezing onset of any sample. A closure study connecting NINP in fog water and the ambient NINP derived from the filter samples shows good agreement of the concentrations in both compartments, which indicates that INPs in the air are likely all activated into fog droplets during fog events. In a case study we considered a situation during which the ship was located in the marginal sea ice zone and NINP in air and the SML were highest in the temperature range above −10° C. Chlorophyll-a measurements by satellite remote sensing point towards the waters in the investigated region being biologically active. Heat induced reduction of ice nucleating ability indicated the biogenic nature of the air-borne INPs. Similar slopes in the temperature spectra suggested a connection between the INP populations in the SML and the air. Air mass history had no influence on the observed air-borne INP population. Therefore, we conclude that during the case study collected air-borne INPs originated from a local biogenic probably marine source.

Citation: Hartmann, M., Gong, X., Kecorius, S., van Pinxteren, M., Vogl, T., Welti, A., Wex, H., Zeppenfeld, S., Herrmann, H., Wiedensohler, A., and Stratmann, F.: Terrestrial or marine? – Indications towards the origin of Ice Nucleating Particles during melt season in the European Arctic up to 83.7° N, Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-1211, in review, 2020.

WashU affiliated authors: Jonathan Myers (Dept. of Biology)

Abstract:

1. Understanding how abiotic disturbance and biotic interactions determine pollinator and flowering‐plant diversity is critically important given global climate change and widespread pollinator declines. To predict responses of pollinators and flowering‐plant communities to changes in wildfire disturbance, a mechanistic understanding of how these two trophic levels respond to wildfire severity is needed.
2. We compared site‐to‐site variation in community composition (β‐diversity), species richness and abundances of pollinators and flowering plants among landscapes with no recent wildfire (unburned), mixed‐severity wildfire and high‐severity wildfire in three sites across the Northern Rockies Ecoregion, USA. We used variation partitioning to assess the relative contributions of wildfire, other abiotic variables (climate, soils and topography) and biotic associations among plant and pollinator composition to community assembly of both trophic levels.
3. Wildfire disturbance generally increased species richness and total abundance, but decreased β‐diversity, of both pollinators and flowering plants. However, reductions in β‐diversity from wildfire appeared to result from increased abundances following fires, resulting in higher local species richness of pollinators and flowers in burned than unburned landscapes. After accounting for differences in abundance, standardized effect sizes of β‐diversity were higher in burned than unburned landscapes, suggesting that wildfire enhances non‐random assortment of pollinator and flowering‐plant species among local communities.
4. Wildfire disturbance mediated the relative importance of mutualistic associations to β‐diversity of pollinators and flowering plants. The influence of pollinator β‐diversity on flowering‐plant β‐diversity increased with wildfire severity, whereas the influence of flowering‐plant β‐diversity on pollinator β‐diversity was greater in mixed‐severity than high‐severity wildfire or unburned landscapes. Moreover, biotic associations among pollinator and plant species explained substantial variation in β‐diversity of both trophic levels beyond what could be explained by wildfire and all other abiotic and spatial factors combined.
5. Synthesis. Wildfire disturbance and plant–pollinator interactions both strongly influenced the assembly of pollinator and flowering‐plant communities at local and regional scales. However, biotic interactions were generally more important drivers of community assembly in disturbed than undisturbed landscapes. As wildfire regimes continue to change globally, predicting its effects on biodiversity will require a deeper understanding of the ecological processes that mediate biotic interactions among linked trophic levels.

Citation: LaManna, JA, Burkle, LA, Belote, RT, Myers, JA. Biotic and abiotic drivers of plant–pollinator community assembly across wildfire gradients. J Ecol. 2020; 00: 1– 14. https://doi.org/10.1111/1365-2745.13530

WashU affiliated authors: Kun Wang, Heng Chen, Heather Lee, (Dept. of Earth and Planetary Sciences and McDonnell Center for the Space Sciences)

Abstract: High-precision potassium (K) isotope ratios have recently been proposed as a new tool for tracing continental weathering and reconstructing Earth’s past climates. The premise is that the K isotopic composition of seawater is sensitive to terrestrial weathering changes. Modern seawater (δ41KNIST SRM3141a = +0.12±0.07‰) is significantly enriched in heavy K isotopes compared to the Bulk Silicate Earth (BSE) and the Upper Continental Crust (UCC). However, the controls causing such a large isotopic fractionation between these two major reservoirs are not well understood. Dissolved K in river water is one of the major inputs of K to seawater. To constrain the poorly defined K isotopic composition of riverine input to the global ocean and to understand the controlling factors of the K isotope composition of seawater, we analyzed the K isotopic composition of 32 river samples from 24 major rivers globally. These rivers drain all continents except Antarctica and collectively account for 40% of the annual global river discharge and 39% of the total K flux into the ocean. We observed a large range in K isotopic composition across all the rivers analyzed, ranging from δ41K = −0.59±0.04‰ to −0.08±0.04‰, but found no significant K isotopic variations among samples collected from the same river under differing flow conditions. We attribute the dissolved K isotopic composition of global rivers to the fraction of K retained in clay minerals during chemical weathering. Isotopically light K is retained with the clay fraction during weathering leading to heavy isotopic enrichment in the dissolved K load relative to the BSE and UCC. The flux-weighted and regionally-adjusted mean composition of all rivers studied here (−0.38±0.04‰) serves as a global estimate of the riverine δ41K value. The seawater K isotopic composition (i.e., +0.12±0.07‰) cannot be explained solely by the riverine input. Other mechanisms (hydrothermal input, reverse weathering, biological fractionation) are needed to explain seawater K isotopic composition.

Citation: Kun Wang (王昆), Bernhard Peucker-Ehrenbrink, Heng Chen, Heather Lee, Elizabeth A. Hasenmueller, Dissolved potassium isotopic composition of major world rivers, Geochimica et Cosmochimica Acta, 2020, ISSN 0016-7037, https://doi.org/10.1016/j.gca.2020.11.012.

WashU affiliated authors: Xinyi Liu (Dept. of Anthropology)

Abstract: We conducted a meta-analysis of published carbon and nitrogen isotope data from archaeological human skeletal remains (n = 2448) from 128 sites cross China in order to investigate broad spatial and temporal patterns in the formation of staple cuisines. Between 6000–5000 cal BC we found evidence for an already distinct north versus south divide in the use of main crop staples (namely millet vs. a broad spectrum of C3 plant based diet including rice) that became more pronounced between 5000–2000 cal BC. We infer that this pattern can be understood as a difference in the spectrum of subsistence activities employed in the Loess Plateau and the Yangtze-Huai regions, which can be partly explained by differences in environmental conditions. We argue that regional differentiation in dietary tradition are not driven by differences in the conventional “stages” of shifting modes of subsistence (hunting-foraging-pastoralism-farming), but rather by myriad subsistence choices that combined and discarded modes in a number of innovative ways over thousands of years. The introduction of wheat and barley from southwestern Asia after 2000 cal BC resulted in the development of an additional east to west gradient in the degree of incorporation of the different staple products into human diets. Wheat and barley were rapidly adopted as staple foods in the Continental Interior contra the very gradual pace of adoption of these western crops in the Loess Plateau. While environmental and social factors likely contributed to their slow adoption, we explored local cooking practice as a third explanation; wheat and barley may have been more readily folded into grinding-and-baking cooking traditions than into steaming-and-boiling traditions. Changes in these culinary practices may have begun in the female sector of society.

Citation: Liu X, Reid REB (2020) The prehistoric roots of Chinese cuisines: Mapping staple food systems of China, 6000 BC–220 AD. PLoS ONE 15(11): e0240930. https://doi.org/10.1371/journal.pone.0240930

WashU affiliated authors: Aaron van Donkelaar, Randall V. Martin (Dept. of Energy, Environmental & Chemical Engineering)

Abstract: Rationale: Current evidence on the relationship between long-term exposure to air pollution and new onset of chronic lung disease is inconclusive. Objective: To examine associations of incident chronic obstructive pulmonary disease (COPD) and adult-onset asthma with past exposure to fine particulate matter (PM2.5), nitrogen dioxide (NO2), ozone (O3), and the redox-weighted average of NO2 and O3 (Ox), and characterize the concentration-response relationship. Methods: We conducted a population-based cohort study of all Ontarians, aged 35 to 85 years, from 2001 to 2015. 3-year moving average of residential exposures to selected pollutants with 1-year lag were estimated during follow-up. We used Cox proportional and Aalen’s additive hazards models to quantify the pollution-disease associations, and characterized the shape of these relationships using newly developed non-linear risk models. Measurements and Main Results: Among 5.1 million adults, we identified 340,733 and 218,005 incident cases of COPD and asthma, respectively. We found positive associations of COPD with PM2.5 per interquartile-range (IQR) increase of 3.4µg/m3 (hazard ratio, 1.07; 95% confidence interval, 1.06-1.08), NO2 per 13.9ppb (1.04; 1.02-1.05), O3 per 6.3ppb (1.04; 1.03-1.04), and Ox per 4.4ppb (1.03; 1.03-1.03). By contrast, we did not find strong evidence linking these pollutants to adult-onset asthma. Additionally, we quantified that each IQR increase in pollution exposure yielded 3.0 (2.4-3.6) excess cases of COPD per 100,000 adults for PM2.5, 3.2 (2.0-4.3) for NO2, 1.9 (1.3-2.5) for O3, 2.3 (1.7-2.9) for Ox. Furthermore, most pollutant-COPD relationships exhibited supralinear shapes. Conclusions: Air pollution was associated with higher incidence of COPD, but not adult-onset asthma.

Citation: Shin, Saeha, Li Bai, Richard T. Burnett, Jeffrey C. Kwong, Perry Hystad, Aaron van Donkelaar, Eric Lavigne et al. “Air Pollution as a Risk Factor for Incident COPD and Asthma: 15-Year Population-Based Cohort Study.” American Journal of Respiratory and Critical Care Medicine ja (2020). https://doi.org/10.1164/rccm.201909-1744OC.

WashU affiliation: Weidenbaum Center on the Economy, Government, and Public Policy

Introduction: One of the issues at the center of the 2020 election is climate change. A recent survey by the Weidenbaum Center at Washington University in St. Louis found that a majority of voters — 95% of Democrats and 54% of Republicans — recognize evidence for climate change. But partisans differ in how serious they view the issue, what they believe is causing global warming and their support for policies to address the problem.

Citation: Savat, Sara. “Majority of All Voters Say Climate Change Is Real; More Democrats Consider It a Problem: The Source: Washington University in St. Louis.” The Source, 1 Nov. 2020, source.wustl.edu/2020/10/majority-of-all-voters-say-climate-change-is-real-more-democrats-consider-it-a-problem/.

WashU affiliated authors: James T. Stroud, Colin M. Donihue, Jonathan B. Losos (Dept. of Biology)

Abstract: Extreme climate events are predicted to increase in frequency and severity due to contemporary climate change. Recent studies have documented the evolutionary impacts of extreme events on single species, but no studies have yet investigated whether such events can drive community-wide patterns of trait shifts. On 22 January 2020, subtropical south Florida experienced an extreme cold episode during which air temperatures dropped below the lower thermal limit of resident lizard populations. In the week immediately after the cold event, we documented decreased lower thermal limits (CTmin) of six co-occurring lizard species that vary widely in ecology, body size and thermal physiology. Although cold tolerance of these species differed significantly before the cold snap, lizards sampled immediately after had converged on the same new, lower limit of thermal tolerance. Here, we demonstrate that extreme climate events can drive substantial and synchronous community-wide trait changes and provide evidence that tropical and subtropical ectotherms—often characterized as unable to withstand rapid changes in climatic conditions—can endure climatic conditions that exceed their physiological limits. Future studies investigating the mechanisms driving these trait shifts will prove valuable in understanding the ability of ectotherm communities to mitigate climate change.

Citation: Stroud James T., Mothes Caitlin C., Beckles Winter, Heathcote Robert J. P., Donihue Colin M. and Losos Jonathan B. 2020. An extreme cold event leads to community-wide convergence in lower temperature tolerance in a lizard community. Biol. Lett. 16: 20200625. http://doi.org/10.1098/rsbl.2020.0625

WashU affiliated authors: Douglas A. Luke (Center for Public Health Systems Science)

Abstract: 

Background: Two of the most important causes of global disease fall in the realm of environmental health: household air pollution (HAP) and poor water, sanitation, and hygiene (WASH) conditions. Interventions, such as clean cookstoves, household water treatment, and improved sanitation facilities, have great potential to yield reductions in disease burden. However, in recent trials and implementation efforts, interventions to improve HAP and WASH conditions have shown few of the desired health gains, raising fundamental questions about current approaches.

Objectives: We describe how the failure to consider the complex systems that characterize diverse real-world conditions may doom promising new approaches prematurely. We provide examples of the application of systems approaches, including system dynamics, network analysis, and agent-based modeling, to the global environmental health priorities of HAP and WASH research and programs. Finally, we offer suggestions on how to approach systems science.

Methods: Systems science applied to environmental health can address major challenges by a) enhancing understanding of existing system structures and behaviors that accelerate or impede aims; b) developing understanding and agreement on a problem among stakeholders; and c) guiding intervention and policy formulation. When employed in participatory processes that engage study populations, policy makers, and implementers, systems science helps ensure that research is responsive to local priorities and reflect real-world conditions. Systems approaches also help interpret unexpected outcomes by revealing emergent properties of the system due to interactions among variables, yielding complex behaviors and sometimes counterintuitive results.

Discussion: Systems science offers powerful and underused tools to accelerate our ability to identify barriers and facilitators to success in environmental health interventions. This approach is especially useful in the context of implementation research because it explicitly accounts for the interaction of processes occurring at multiple scales, across social and environmental dimensions, with a particular emphasis on linkages and feedback among these processes. 

Citation: Joshua Rosenthal, Raphael E. Arku, Jill Baumgartner, Joe Brown, Thomas Clasen, Joseph N.S. Eisenberg, Peter Hovmand ,Pamela Jagger, Douglas A. Luke, Ashlinn Quinn, and Gautam N. Yadama 2020. Systems Science Approaches for Global Environmental Health Research: Enhancing Intervention Design and Implementation for Household Air Pollution (HAP) and Water, Sanitation, and Hygiene (WASH) Programs. Environmental Health Perspectives 128:10 CID: 105001 https://doi.org/10.1289/EHP7010.

WashU affiliated authors: Natalie G. Mueller, Kunsang Lama (Dept. of Anthropology)

Abstract: Scholars have argued that plant domestication in eastern North America involved human interactions with floodplain weeds in woodlands that had few other early successional environments. Archeological evidence for plant domestication in this region occurs along the Mississippi river and major tributaries such as the Tennessee, Ohio, Illinois, Missouri, and Arkansas rivers. But this region is also known as the prairie peninsula: a prairie-woodland mosaic that was maintained by anthropogenic fire starting as early as 6000 BP. Contrary to conventional wisdom, recent research has shown that bison were also present in the prairie peninsula throughout the Holocene. Recent reintroductions of bison to tallgrass prairies have allowed ecologists to study the effects of their grazing on this ecosystem for the first time. Like rivers and humans, bison create early successional habitats for annual forbs and grasses, including the progenitors of eastern North American crops, within tallgrass prairies. Our fieldwork has shown that crop progenitors are conspicuous members of plant communities along bison trails and in wallows. We argue that ancient foragers encountered dense, easily harvestable stands of crop progenitors as they moved along bison trails, and that the ecosystems created by bison and anthropogenic fire served as a template for the later agroecosystem of this region. Without denying the importance of human-river interactions highlighted by previous researchers, we suggest that prairies have been ignored as possible loci for domestication, largely because the disturbed, biodiverse tallgrass prairies created by bison have only been recreated in the past three decades after a century of extinction.

Citation: Mueller NG, Spengler RN, Glenn A, Lama K. Bison, anthropogenic fire, and the origins of agriculture in eastern North America. The Anthropocene Review. October 2020. doi:10.1177/2053019620961119

WashU affiliated authors: Rachel Penczykowski, Amanda Koltz (Dept. of Biology

Abstract: Ruminant livestock are a significant contributor to global methane emissions. Infectious diseases have the potential to exacerbate these contributions by elevating methane outputs associated with animal production. With the increasing spread of many infectious diseases, the emergence of a vicious climate–livestock–disease cycle is a looming threat.

Citation: Ezenwa, Vanessa O., David J. Civitello, Brandon T. Barton, Daniel J. Becker, Maris Brenn-White, Aimée T. Classen, Sharon L. Deem et al. “Infectious Diseases, Livestock, and Climate: A Vicious Cycle?.” Trends in Ecology & Evolution (2020). https://doi.org/10.1016/j.tree.2020.08.012

WashU affiliated authors: Jian Wang and Jiaoshi Zhang (Dept. of Energy, Environmental and Chemical Engineering)

Abstract: The tropical Western North Pacific (TWNP) is a receptor for pollution sources throughout Asia and is highly susceptible to climate change, making it imperative to understand long-range transport in this complex aerosol-meteorological environment. Measurements from the NASA Cloud, Aerosol, and Monsoon Processes Philippines Experiment (CAMP2Ex; 24 Aug to 5 Oct 2019) and back trajectories from the National Oceanic and Atmospheric Administration Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT) were used to examine transport into the TWNP from the Maritime Continent (MC), Peninsular Southeast Asia (PSEA), East Asia (EA), and West Pacific (WP). A mid-campaign monsoon shift on 20 Sep 2019 led to distinct transport patterns between the southwest monsoon (before 20 Sep) and monsoon transition (after 20 Sep). During the southwest monsoon, long-range transport was a function of southwesterly winds and cyclones over the South China Sea. Low (high) altitude air generally came from MC (PSEA), implying distinct aerosol processing related to convection and perhaps wind shear. The monsoon transition saw transport from EA and WP, driven by Pacific northeasterly winds, continental anticyclones, and cyclones over the East China Sea. Composition of transported air differed by emission source and accumulated precipitation along trajectories (APT) as an indicator of convection. MC air was characterized by biomass burning tracers while major components of EA air pointed to Asian outflow and secondary formation. Convective scavenging of PSEA air was evidenced by considerable vertical differences between aerosol species but not trace gases, as well as notably higher APT and smaller particles than other regions. Finally, we observed a possible wet scavenging mechanism acting on MC air aloft that was not strictly linked to precipitation. These results are important for understanding the transport and processing of air masses with further implications for modeling aerosol lifecycles and guiding international policymaking on public health and climate.

Citation: Hilario, M. R. A., Crosbie, E., Shook, M., Reid, J. S., Cambaliza, M. O. L., Simpas, J. B. B., Ziemba, L., DiGangi, J. P., Diskin, G. S., Nguyen, P., Turk, J., Winstead, E., Robinson, C. E., Wang, J., Zhang, J., Wang, Y., Yoon, S., Flynn, J., Alvarez, S. L., Behrangi, A., and Sorooshian, A.: Long-range transport patterns into the tropical northwest Pacific during the CAMP2Ex aircraft campaign: chemical composition, size distributions, and the impact of convection, Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-961, in review, 2020.

WashU affiliated authors: Michael Bechtel, Dept. of Political science

Abstract: The introduction of policies that increase the price of carbon is central to limiting the adverse effects of global warming. Conventional wisdom holds that, of the possible cost paths, gradually raising costs relating to climate action will receive the most public support. Here, we explore mass support for dynamic cost paths in four major economies (France, Germany, the United Kingdom and the United States). We find that, for a given level of average costs, increasing cost paths receive little support whereas constant cost schedules are backed by majorities in all countries irrespective of whether those average costs are low or high. Experimental evidence indicates that constant cost paths significantly reduce opposition to climate action relative to increasing cost paths. Preferences for climate cost paths are related to the time horizons of individuals and their desire to smooth consumption over time.

Citation: Bechtel, M.M., Scheve, K.F. & van Lieshout, E. Constant carbon pricing increases support for climate action compared to ramping up costs over time. Nat. Clim. Chang. (2020). https://doi.org/10.1038/s41558-020-00914-6

WashU affiliated authors: Longfei Shu, Xinye Qian, Debra A. Brock, Katherine S. Geist, David C. Queller, Joan E. Strassmann (Dept. of Biology)

Abstract: Anthropogenic global change is increasingly raising concerns about collapses of symbiotic interactions worldwide. Therefore, understanding how climate change affects symbioses remains a challenge and demands more study. Here, we look at how simulated warming affects the social ameba Dictyostelium discoideum and its relationship with its facultative bacterial symbionts, Paraburkholderia hayleyella and Paraburkholderia agricolaris. We cured and cross-infected ameba hosts with different symbionts. We found that warming significantly decreased D. discoideum’s fitness, and we found no sign of local adaptation in two wild populations. Experimental warming had complex effects on these symbioses with responses determined by both symbiont and host. Neither of these facultative symbionts increases its hosts’ thermal tolerance. The nearly obligate symbiont with a reduced genome, P. hayleyella, actually decreases D. discoideum’s thermal tolerance and even causes symbiosis breakdown. Our study shows how facultative symbioses may have complex responses to global change.

Citation: Shu, Longfei, Xinye Qian, Debra A. Brock, Katherine S. Geist, David C. Queller, and Joan E. Strassmann. “Loss and resiliency of social amoeba symbiosis under simulated warming.” Ecology and Evolution.

WashU affiliated authors: Jordan Brock, Trey Scott, Amy Yoojin Lee, Kenneth Olsen (Dept. of Biology)

Abstract:

Background: Camelina sativa (gold-of-pleasure) is a traditional European oilseed crop and emerging biofuel source with high levels of desirable fatty acids. A twentieth century germplasm bottleneck depleted genetic diversity in the crop, leading to recent interest in using wild relatives for crop improvement. However, little is known about seed oil content and genetic diversity in wild Camelina species.

Results: We used gas chromatography, environmental niche assessment, and genotyping-by-sequencing to assess seed fatty acid composition, environmental distributions, and population structure in C. sativa and four congeners, with a primary focus on the crop’s wild progenitor, C. microcarpa. Fatty acid composition differed significantly between Camelina species, which occur in largely non-overlapping environments. The crop progenitor comprises three genetic subpopulations with discrete fatty acid compositions. Environment, subpopulation, and population-by-environment interactions were all important predictors for seed oil in these wild populations. A complementary growth chamber experiment using C. sativa confirmed that growing conditions can dramatically affect both oil quantity and fatty acid composition in Camelina.

Conclusions: Genetics, environmental conditions, and genotype-by-environment interactions all contribute to fatty acid variation in Camelina species. These insights suggest careful breeding may overcome the unfavorable FA compositions in oilseed crops that are predicted with warming climates.

Citation: Brock, J.R., Scott, T., Lee, A.Y. et al. Interactions between genetics and environment shape Camelina seed oil composition. BMC Plant Biol 20, 423 (2020). https://doi.org/10.1186/s12870-020-02641-8.

WashU affiliated authors: Xuanhao Wu (Dept. of Energy, Environmental and Chemical Engineering), Sisi Cao (Dept. of Mechanical Engineering and Materials Science), Deoukchen Ghim (Dept. of Energy, Environmental and Chemical Engineering), Qisheng Jiang (Dept. of Mechanical Engineering and Materials Science), Srikanth Singamaneni, (Dept. of Mechanical Engineering and Materials Science), Young-Shin Jun (Dept. of Energy, Environmental and Chemical Engineering)

Abstract: Solar energy holds great promise for sustainable desalination to alleviate global water scarcity. Recently developed solar steam generation relying on interfacial evaporators has high solar energy-to-steam efficiency (60–90%), but its vapor collection efficiency is low, typically ∼30%. Here, we present a solar-driven photothermal membrane distillation (PMD) system that offers easy and highly efficient clean vapor generation, condensation, and collection. The photothermal membrane is thermally-engineered to incorporate a bilayer structure composed of two environmentally-sustainable materials, polydopamine (PDA) particles and bacterial nanocellulose (BNC), and it achieved a permeate flux of 1.0 kg m−2 h−1 under 1 sun irradiation and a high solar energy-to-collected water efficiency of 68%. The thermally-engineered strategy of using a bilayer structure ensures superb optical/photothermal activities, maximized membrane porosity (∼93%), and reduced conductive heat transfer, thus increasing the thermal efficiency of the membrane. The strong chemically-bonded fluorosilane functional groups on the membrane surface provide stable hydrophobicity and high salt rejection (>99.9%). Moreover, under solar irradiation, the membrane shows effective interfacial photothermal disinfection to kill bacteria, enabling easy cleaning and increasing its lifespan. Using solar energy, the PMD system presented here can provide advantageous decentralized desalination for remote areas, and can support resilient community development.

Citation: Xuanhao Wu, Sisi Cao, Deoukchen Ghim, Qisheng Jiang, Srikanth Singamaneni, Young-Shin Jun, A thermally engineered polydopamine and bacterial nanocellulose bilayer membrane for photothermal membrane distillation with bactericidal capability, Nano Energy, 2020, 105353, ISSN 2211-2855, https://doi.org/10.1016/j.nanoen.2020.105353.

WashU affiliated authors: Rebecca Dudley, Dept. of Anthropology

Introduction: In Cultivating Knowledge, Andrew Flachs examines cotton farming in southeastern India from a political-ecological perspective to assess the effects of global technological and economic pressures in cotton production on farmers’ agricultural knowledge. Specifically, he considers aspects of farming, such as seed selection and farming-as-performance, within social, political, and economic institutions. Focusing on two groups of cotton farmers in Telangana, India, one which cultivates genetically modified (GM) cotton (also referred to as Bt cotton, reflecting its genetic donor, Bacterium thuringiensis) and one which farms organically, Flachs provides a comparison between their responses to global agricultural trends. The former group relies on seed and farm input sellers to make decisions about what to plant and how to cultivate, while the latter are supported and constrained by non-governmental development organizations (development NGOs) on which they depend to maintain funding and which require them to use certain agricultural practices while demonstrating such practices in a public and educational manner. This ‘performative’ agriculture becomes a viable path for rural well being, Flachs asserts, because the NGOs in turn underwrite agricultural risk for farmers. Flachs argues that it is not the characteristics of the seed that primarily affects farmers’ agricultural knowledge, as agribusiness and development discourse might suggest, but rather social, economic, and political pressures that motivate and drive farmers’ decisions on seed selection.

Citation: Dudley, R. Andrew Flachs. Cultivating Knowledge: Biotechnology, Sustainability, and the Human Cost of Cotton Capitalism in South India. Hum Ecol 48, 515–517 (2020). https://doi.org/10.1007/s10745-020-00175-z

WashU affiliated authors: Amy Eyler, Dept. of Public Health-Social Work

Abstract: Physical activity is vital for the health and well-being of youth and adults, although the prevalence of physical activity continues to be low. Promoting active transportation or human-powered transportation through policy, systems, and environmental change is one of the leading evidence-based strategies to increase physical activity regardless of age, income, racial/ethnic background, ability, or disability. Initiatives often require coordination across federal, state, and local agencies. To maximize the effectiveness of all types of interventions, it is imperative to establish strong and broad partnerships across professional disciplines, community members, and advocacy groups. Health organizations can play important roles in facilitating these partnerships. This policy statement provides recommendations and resources that can improve transportation systems, enhance land use design, and provide education to support policies and environments to promote active travel. The American Heart Association supports safe, equitable active transportation policies in communities across the country that incorporate consistent implementation evaluation. Ultimately, to promote large increases in active transportation, policies need to be created, enforced, and funded across multiple sectors in a coordinated and equitable fashion. Active transportation policies should operate at 3 levels: the macroscale of land use, the mesoscale of pedestrian and bicycle networks and infrastructure such as Complete Streets policies and Safe Routes to School initiatives, and the microscale of design interventions and placemaking such as building orientation and access, street furnishings, and safety and traffic calming measures. Health professionals and organizations are encouraged to become involved in advocating for active transportation policies at all levels of government.

Citation: Young DR, Cradock AL, Eyler AA, Fenton M, Pedroso M, Sallis JF, Whitsel LP; on behalf of the American Heart Association Advocacy Coordinating Committee. Creating built environments that expand active transportation and active living across the United States: a policy statement from the American Heart Association. Circulation. 2020;142:e000–e000. doi: 10.1161/CIR.0000000000000878.

WashU affiliated authors: Carlos Botero, Dept. of Biology

Abstract: Adaptive responses to ecological uncertainty may affect the dynamics of interspecific interactions and shape the course of evolution within symbioses. Obligate avian brood parasites provide a particularly tractable system for understanding how uncertainty, driven by environmental variability and symbiont phenology, influences the evolution of species interactions. Here, we use phylogenetically-informed analyses and a comprehensive dataset on the behaviour and geographic distribution of obligate avian brood parasites and their hosts to demonstrate that increasing uncertainty in thermoregulation and parental investment of parasitic young are positively associated with host richness and diversity. Our findings are consistent with the theoretical expectation that ecological risks and environmental unpredictability should favour the evolution of bet-hedging. Additionally, these highly consistent patterns highlight the important role that ecological uncertainty is likely to play in shaping the evolution of specialisation and generalism in complex interspecific relationships.

Citation: Antonson, N.D., Rubenstein, D.R., Hauber, M.E. et al. Ecological uncertainty favours the diversification of host use in avian brood parasites. Nat Commun 11, 4185 (2020). https://doi.org/10.1038/s41467-020-18038-y

WashU affiliated authors: Jian Wang, Dept. of Energy, Environmental and Chemical Engineering

Abstract: In the current global climate models (GCM), the nonlinearity effect of subgrid cloud variations on the parameterization of warm rain process, e.g., the autoconversion rate, is often treated by multiplying the resolved-scale warm ran process rates by a so-called enhancement factor (EF). In this study, we investigate the subgrid-scale horizontal variations and covariation of cloud water content (qc) and cloud droplet number concentration (Nc) in marine boundary layer (MBL) clouds based on the in-situ measurements from a recent field campaign, and study the implications for the autoconversion rate EF in GCMs. Based on a few carefully selected cases from the field campaign, we found that in contrast to the enhancing effect of qc and Nc variations that tends to make EF > 1, the strong positive correlation between qc and Nc results in a suppressing effect that makes tends to make EF < 1. This effect is especially strong at cloud top where the qc and Nc correlation can be as high as 0.95. We also found that the physically complete EF that accounts for the covariation of qc and Nc has a robust decreasing trend from cloud base to cloud top. Because the autoconversion process is most important at the cloud top, this vertical dependence of EF should be taken into consideration in the GCM parametrization scheme.

Citation: Zhang, Zhibo, Qianqian Song, David Mechem, Vincent Larson, Jian Wang, Yangang Liu, Mikael Witte, Xiquan Dong, and Peng Wu. “Vertical Dependence of Horizontal Variation of Cloud Microphysics: Observations from the ACE-ENA field campaign and implications for warm rain simulation in climate models.” Atmospheric Chemistry and Physics Discussions (2020): 1-46. https://doi.org/10.5194/acp-2020-788

WashU affiliated authors: J. Garrecht Metzger, David A. Fike (Dept. of Earth and Planetary Sciences)

Abstract: Perturbations to the global carbon cycle as recorded in the isotopic compositions of marine deposits have been commonly associated with major shifts in the climate and/or biologic activity, including mass extinctions. The Late Ordovician Guttenberg isotopic carbon excursion (GICE) is a large, globally correlative positive shift (∼3‰) in the carbon isotopic composition of marine carbonates (δ¹³C_carb), but its driving mechanism(s) remains ambiguous. This is in large part due to uncertain correlations among Late Ordovician records, as well as complex and poorly constrained temporal relationships of abundant K-bentonite (altered volcanic ash) marker beds deposited in this time interval. Here, we provide new, high-precision U-Pb zircon geochronology by chemical-abrasion−isotope-dilution−thermal ionization mass spectrometry for K-bentonites bounding the GICE in the North American Midcontinent, including robust ²⁰⁶Pb/²³⁸U ages (reported with 2σ analytical uncertainty) for two important regional markers: the Deicke (453.35 ± 0.10 Ma) and Millbrig (453.36 ± 0.14 Ma) K-bentonites. The new data from these K-bentonites directly constrain the duration of the GICE to less than 400 k.y. at two well-studied locations in eastern Missouri, United States. The abruptness of the GICE precludes relatively gradual tectonic mechanisms as possible drivers of the excursion and suggests more rapid environmental drivers, such as changes in eustatic sea level associated with pre-Hirnantian glacial activity.

Citation: Metzger, J. Garrecht, Jahandar Ramezani, Samuel A. Bowring, and David A. Fike. “New age constraints on the duration and origin of the Late Ordovician Guttenberg δ13Ccarb excursion from high-precision U-Pb geochronology of K-bentonites.” GSA Bulletin (2020). https://doi.org/10.1130/B35688.1

WashU affiliated authors: Jonathan Lewis and Jennifer R. Smith (Dept. of Earth and Planetary Sciences)

Abstract: Holocene environmental change in the northern and central Nile Valley was controlled primarily by shifts in the Intertropical Convergence Zone over time, leading to changes in aridity and water availability for early occupants of the region. Although local environmental changes may help to motivate societal changes such as those in settlement patterns or technological productions, evidence from pedogenic carbonates at Sai Island, in northern Sudan, indicate that the most significant environmental changes predated a key shift in local food production from foraging to pastoralism. Changes in local environmental conditions from a wetter and more diverse vegetative context to a more arid and C4‐dominant landscape occurred during the occupation of Khartoum Variant foragers, whereas later Abkan pastoralists arrived without any notable differences in the region compared to the environments inhabited by the most recent foragers. The lack of an external environmental driver for food production changes at Sai suggests that other, potentially cultural factors were more important in these economic decisions in the mid‐Holocene.

Citation: Adelsberger, Katherine A., Jonathan Lewis, Justin P. Dodd, Danika Hill, Jennifer R. Smith, and Elena AA Garcea. “Mid‐Holocene environmental change and human occupation at Sai Island, Northern Sudan.” Geoarchaeology. https://doi.org/10.1002/gea.21812

WashU affiliated authors: Randall V. Martin (Dept. of Energy, Environmental, and Chemical Engineering)

Abstract: Satellite-based estimates of ground-level nitrogen dioxide (NO2) concentrations are useful for understanding links between air quality and health. A longstanding question has been why prior satellite-derived surface NO2 concentrations are biased low with respect to ground-based measurements. In this work we demonstrate that these biases are due to both the coarse resolution of previous satellite NO2 products and inaccuracies in vertical mixing assumptions used to convert satellite-observed tropospheric columns to surface concentrations. We develop an algorithm that now allows for different mixing assumptions to be used based on observed NO2 conditions. We then apply this algorithm to observations from the TROPOMI satellite instrument, which has been providing NO2 column observations at an unprecedented spatial resolution for over a year. This new product achieves estimates of ground-level NO2 with greater accuracy and higher resolution compared to previous satellite-based estimates from OMI. These comparisons also show that TROPOMI-inferred surface NO2 concentrations from our updated algorithm have higher correlation and lower bias than those found using TROPOMI and the prior algorithm. TROPOMI-inferred estimates of the population exposed to NO2 conditions exceeding health standards are at least three times higher than for OMI-inferred estimates. These developments provide an exciting opportunity for air quality monitoring.

Citation: Cooper, Matthew J., Randall V. Martin, Chris A. McLinden, and Jeffrey R. Brook. “Inferring ground-level nitrogen dioxide concentrations at fine spatial resolution applied to the TROPOMI satellite instrument.” Environmental Research Letters (2020). https://doi.org/10.1088/1748-9326/aba3a5

WashU’s involvement: This project was funded and enabled by the Nano Research Facility at Washington University.

Abstract: Ancient soils contain geochemical signatures of human land use, making them usable as a “golden spike,” or globally synchronous marker, to identify traces of the early “Anthropocene.” This article examines the sedimentary record in northern China to determine when, and under what cultural circumstances, did ancient pollution appear in buried soils and sediments. Using methods of Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and Local Enrichment Factor (LEF), we analyzed the elemental geochemistry of soil and sediment samples (n = 333) that span the Holocene from three rural sedimentary sequences in Henan Province. We compared results to geochemical data from a 2000-year sequence of urban occupation from the nearby city of Kaifeng. We expected to find higher concentrations of heavy metals in anthropogenic soils at both rural and urban locations, as pollution from human activities intensified as a result of pre-modern industrialization around 1000 BP. Instead, ancient soils in rural contexts are moderately enriched (LEF ≈ 6) in several metals (Arsenic, Barium, Zinc, and Lead) starting around the Bronze Age (ca. 4000-3000 BP). Additionally, after 1000 BP, most soils show no significant enrichment. At the urban site of Kaifeng, ancient soils have heavy metal concentrations (Zinc and Lead) an order of magnitude greater than the rural sites. This study showed that, while anthropogenic soils are sinks for ancient pollution, they contain a signature that must be understood within a localized geochemical context. Anthropogenic soils are therefore a useful proxy for defining the geographic extent, and thus the patchiness, of ancient human land use activities, rather than a “golden spike” of the early “Anthropocene.”

Citation: Storozum, Michael J., Zhen Qin, Yiming V. Wang, and Haiwang Liu. “Buried soils as archives of paleo-pollution in the North China Plain.” Anthropocene (2020): 100251. https://doi.org/10.1016/j.ancene.2020.100251

WashU affiliated authors: Boahemaa Adu-Oppong (Edison Family Center for Genome Sciences & Systems Biology), Scott A. Mangan (Dept. of Biology and Tyson Research Center), Christopher P. Catano (Dept. of Biology and Tyson Research Center), Jonathan A. Myers (Dept. of Biology and Tyson Research Center), Gautam Dantas (The Edison Family Center for Genome Sciences and Systems Biology)

Abstract: Plant-soil feedback studies attempt to understand the interplay between composition of plant and soil microbial communities. A growing body of literature suggests that plant species can coexist when they interact with a subset of the soil microbial community that impacts plant performance. Most studies focus on the microbial community in the soil rhizosphere; therefore, the degree to which the bacterial community within plant roots (root-endophytic compartment) influences plant-microbe interactions remains relatively unknown. To determine if there is an interaction between conspecific vs heterospecific soil microbes and plant performance, we sequenced root-endophytic bacterial communities of five tallgrass-prairie plant species, each reciprocally grown with soil microbes from each hosts’ soil rhizosphere. We found evidence of plant-soil feedbacks for some pairs of plant hosts; however, the strength and direction of feedbacks varied substantially across plant species pairs–from positive to negative feedbacks. Additionally, each plant species harbored a unique subset of root-endophytic bacteria. Conspecifics that hosted similar bacterial communities were more similar in biomass than individuals that hosted different bacterial communities, suggesting an important functional link between root-endophytic bacterial community composition and plant fitness. Our findings suggest a connection between an understudied component of the root-endophytic microbiome and plant performance, which may have important implications in understanding plant community composition and coexistence.

Citation: Boahemaa Adu-Oppong, Scott A. Mangan (Biology and Tyson Research Center), Claudia Stein, Christopher P. Catano, Jonathan A. Myers, and Gautam Dantas. “Prairie plants harbor distinct and beneficial root-endophytic bacterial communities.” PLoS One 15, no. 6 (2020): e0234537. https://doi.org/10.1371/journal.pone.0234537

WashU affiliated authors: Randall V. Martin and Jun Meng (Dept. of Energy, Environmental, and Chemical Engineering)

Abstract: Changes in CO2 emissions during the COVID-19 pandemic have been estimated from indicators on activities like transportation and electricity generation. Here, we instead use satellite observations together with bottom-up information to track the daily dynamics of CO2 emissions during the pandemic. Unlike activity data, our observation-based analysis can be independently evaluated and can provide more detailed insights into spatially-explicit changes. Specifically, we use TROPOMI observations of NO2 to deduce ten-day moving averages of NOx and CO2 emissions over China, differentiating emissions by sector and province. Between January and April 2020, China’s CO2 emissions fell by 11.5% compared to the same period in 2019, but emissions have since rebounded to pre-pandemic levels owing to the fast economic recovery in provinces where industrial activity is concentrated.

Citation: Zheng, Bo, Guannan Geng, Philippe Ciais, Steven J. Davis, Randall V. Martin, Jun Meng, Nana Wu et al. “Satellite-based estimates of decline and rebound in China’s CO₂ emissions during COVID-19 pandemic.” arXiv preprint arXiv:2006.08196 (2020).

WashU affiliated authors: Jordan H. McAllister and Keith Schnakenberg (Dept. of Political Science)

Abstract: We analyze the design of an international climate agreement. In particular, we consider two goals of such an agreement: overcoming free-rider problems and adjusting for differences in mitigation costs between countries. Previous work suggests that it is difficult to achieve both of these goals at once under asymmetric information because countries free ride by exaggerating their abatement costs. We argue that independent information collection (investigations) by an international organization can mitigate this problem. In fact, though the best implementable climate agreement without investigations fails to adjust for individual differences even with significant enforcement power, a mechanism with investigations allows such adjustment and can allow implementation of the socially optimal agreement. Furthermore, when the organization has significant enforcement power the optimal agreement is achievable with minimal investigation costs. The results suggest that discussions about institutions for climate cooperation should focus on information collection as well as enforcement.

Citation: McAllister, Jordan H., and Keith Schnakenberg. “Informational and Flexibility in the Design of International Climate Agreements.” (2020).

WashU affiliated authors: Erin E. McDuffie (Dept. of Energy, Environmental, and Chemical Engineering)

Abstract: Global anthropogenic emission inventories remain vital for understanding the fate and transport of atmospheric pollution, as well as the resulting impacts on the environment, human health, and society. Rapid changes in today’s society require that these inventories provide contemporary estimates of multiple atmospheric pollutants with both source sector and fuel-type information to understand and effectively mitigate future impacts. To fill this need, we have updated the open-source 25 Community Emissions Data System (CEDS) (Hoesly et al., 2019) to develop a new global emission inventory, CEDSGBD-MAPS. This inventory includes emissions of seven key atmospheric pollutants (NOx, CO, SO2, NH3, NMVOCs, BC, OC) over the time period from 1970 – 2017 and reports annual country-total emissions as a function of 11 anthropogenic sectors (agriculture, energy generation, industrial processes, transportation (on-road and non-road), residential, commercial, and other sectors (RCO), waste, solvent use, and international-shipping) and four fuel categories (total coal, solid biofuel, and the sum of liquid 30 fuels and natural gas combustion, plus remaining process-level emissions). The CEDSGBD-MAPS inventory additionally includes global gridded (0.50.5) emission fluxes with monthly time resolution for each compound, sector, and fuel-type to facilitate their use in earth system models. CEDSGBD-MAPS utilizes updated activity data, updates to the core CEDS default calibration procedure, and modifications to the final procedures for emissions gridding and aggregation to retain sector and fuel-specific information. Relative to the previous CEDS data released for CMIP6 (Hoesly et al., 2018), these updates extend the emission 35 estimates from 2014 to 2017 and improve the overall agreement between CEDS and two widely used global bottom-up emission inventories. The CEDSGBD-MAPS inventory provides the most contemporary global emission estimates to-date for these key atmospheric pollutants and is the first to provide global estimates for these species as a function of multiple fueltypes across multiple source sectors. Dominant sources of global NOx and SO2 emissions in 2017 include the combustion of oil, gas, and coal in the energy and industry sectors, as well as on-road transportation and international shipping for NOx. 40 Dominant sources of global CO emissions in 2017 include on-road transportation and residential biofuel combustion. Dominant global sources of carbonaceous aerosol in 2017 include residential biofuel combustion, on-road transportation (BC only), as well as emissions from waste. Global emissions of NOx, SO2, CO, BC, and OC all peak in 2012 or earlier, with more recent emission reductions driven by large changes in emissions from China, North America, and Europe. In contrast, global emissions of NH3 and NMVOCs continuously increase between 1970 and 2017, with agriculture serving as a major source of 45 global NH3 emissions and solvent use, energy, residential, and the on-road transport sectors as major sources of global NMVOCs. Due to similar development methods and underlying datasets, the CEDSGBD-MAPS emissions are expected to have consistent sources of uncertainty as other bottom-up inventories, including uncertainties in the underlying activity data and sector- and region-specific emission factors. The CEDSGBD-MAPS source code is publicly available online through GitHub: https://github.com/emcduffie/CEDS/tree/CEDS_GBD-MAPS. The CEDSGBD-MAPS emission inventory dataset (both annual 50 country-total and global gridded files) is publicly available and registered under: https://doi.org/10.5281/zenodo.3754964 (McDuffie et al., 2020c).

Citation: McDuffie, Erin E., Steven J. Smith, Patrick O’Rourke, Kushal Tibrewal, Chandra Venkataraman, Eloise A. Marais, Bo Zheng, Monica Crippa, Michael Brauer, and Randall V. Martin. “A global anthropogenic emission inventory of atmospheric pollutants from sector-and fuel-specific sources (1970–2017): An application of the Community Emissions Data System (CEDS).” Earth System Science Data Discussions (2020): 1-49. https://doi.org/10.5194/essd-2020-103.

WashU affiliated authors: Ila Sheren (Dept. of Art History and Archaeology)

Abstract: Any discussion of climate change, ecological crisis, or the Anthropocene entails an understanding of the differential experiences of life on a rapidly altered planet. Much of popular eco art focuses sharply on the representation of data, and on visualizing the perspectives of nonhumans. Such strategies, while doing the political work of raising awareness and generating necessary interspecies connections, continue to maintain a troubling neutrality toward human inequality and the nuances of identity. Even when grappling with what Rob Nixon has termed “slow violence” against the global poor, much politically oriented eco art nonetheless frames climate refugees and those affected by environmental crisis as victims, inherently other to the audience. In what follows, I analyze the depiction of toxicity in the work of Indian artist Vibha Galhotra, and argue that reorienting our frame of analysis to privilege a non-Western subaltern reading of the work provides key insights into approaching the depiction of climate change more broadly.

Citation: Sheren, Ila. “Troubling the Waters of Neutrality: Eco Art as an Identity Proposition.” Afterimage: The Journal of Media Arts and Cultural Criticism 47, no. 2 (2020): 28-34. http://online.ucpress.edu/afterimage/article-pdf/47/2/28/403033/aft_47_2_028.pdf

WashU affiliated authors: Danni Hu, Sam Fox School

Abstract: Beyond Coal is a park design project located at the Gateway Mall in St. Louis. Coal has been an essential source of power generation since the 1800s. Coal is a non-renewable resource and causes environmental pollution in the process of using coal to generate electricity. Since the 21st century, there has been a shift from coal to renewable resources. In Missouri, however, coal still generates more than 70 percent of electricity. Coal ash from power generation is buried underground, threatening soil and groundwater resources. Climate change is further exacerbated by the large amounts of greenhouse gases produced by power generation. As a landscape architect living in Missouri, I need to tell the story of coal power to the people who also live in this land. Beyond coal aims to visualize the invisible hazards generated by coal power generation, and make people realize that every kilowatt of electricity we consume is endangering the natural environment and human health. The shape of the Mississippi River is carved on the grounds of the Gateway Mall in St. Louis. Three coal-fired power plants along the river that have a deep impact on St. Louis are being marked on the site. The density of the poles was used as a design tool to represent areas contaminated by coal. At the same time, the project will strongly encourage the use of renewable energy. Solar panels are placed on the facades and roofs of adjacent high-rises to provide power for electric car charging piles on the site. This design is expected to transform the existing park with low popularity through the expression of landscape design. While making the public space more interesting, it also inspires people to think about the pollution caused by coal power generation, thus promoting the transformation from coal to renewable energy.Citation: Hu, Danni, “Beyond Coal: Facing our Landscape Legacy & Seeing our Renewable Future” (2020). Fall 2019 Confluence: St. Louis and Hinterlands. 1. https://openscholarship.wustl.edu/fall2019_stanek/1

A WashU dissertation by: Caitlin Rankin

Abstract: Many archaeologists argue that studying past human response to climate change can be helpful in informing future strategies to adapt to modern effects of climate change; however, archaeological research is rarely utilized in climate change policy. Much of archaeological research involves forming hypotheses to explain observations of past phenomena. However, the advancement of knowledge requires a back and forth between hypothesis forming and hypothesis testing. I argue that a lack of engagement in hypothesis testing has stalled the advancement in archaeological knowledge on the relationship between humans and their environment. Ultimately, it is this stall in the advancement of knowledge that makes archaeological research irrelevant to the fast paced and evolving demands of climate change policy. In this dissertation, I use Cahokia Mounds as a case study of an archaeological site where untested hypotheses related to the relationship between humans and their environment have persisted in academic literature and public discourse for decades. First, I address a hypothesis that deforestation caused increased flooding at the end of Cahokia’s occupation. I use stratigraphic analysis of archaeological excavations conducted in the floodplain of Cahokia Creek to demonstrate that geomorphic conditions were stable from Mississippian occupation (AD 1050 – 1400) until the Industrial Era (mid-1800s). The presence of a stable ground surface from Mississippian occupation to the Industrial Era does not support the expectations of the deforestation hypothesis. Ultimately, this research demonstrates that pre-Colombian ecological change does not inherently cause geomorphic change, and narratives of ecocide related to geomorphic change need to be validated with the stratigraphic record. Second, I address a hypothesis that regional trends of drought caused food insecurity at the end of Cahokia’s occupation. I rely on stable carbon isotope data of buried soil horizons as a proxy of dominant vegetation ground cover changes through time. These data show local ecological resilience to regional trends of drought, demonstrating that the assumed ecological effects of climate change are not universally inherent. Third, I address the hypothesis that the North Plaza complex was drier than modern times during the construction and utilization of this space. The hypothesis that the North Plaza was dry during Mississippian occupation is generally accepted because it fits into preconceived notions about the use of plaza space. I rely on stratigraphic and stable carbon isotope datasets to demonstrate that the North Plaza was a wetland during the construction and utilization this space. Ultimately, the North Plaza hypothesis is great example of how preconceived notions in archaeology can give leeway to accept untested hypotheses. Moving forward, I suggest archaeologists need to be more conscious of the assumptions that are built into explanations of past phenomena and that we should continue to develop research agendas capable of testing these assumptions.

Citation: Rankin, Caitlin G. “Testing Assumptions on the Relationship between Humans and Their Environment: Case Studies from Cahokia Mounds, Illinois.” PhD diss., Washington University in St. Louis, 2020. https://search.proquest.com/openview/b3d0d14b953bb77aa1e42a8f7d36927f/1?pq-origsite=gscholar&cbl=18750&diss=y