Duration: 10/01/2025 to 09/30/2030

Administrative Advisor(s):

NIFA Reps:

Non-Technical Summary

Agroecosystems are stressed under challenging conditions due to changing climate and increasing food demand due to rising global population. Using advanced molecular tools, fundamental research will advance agricultural systems to minimize input while improving agricultural sustainability and profitability. This multistate project has three objectives: 1) Develop advanced molecular and microscopic tools to elucidate fundamental processes governing particulate matter in the environment; 2) Characterize and quantify the physical, chemical, biological, and morphological properties and processes of particulate matter over a wide range of spatial and temporal scales in a changing climate and the resulting impact on ecosystem health, food, and energy production, climate change, air and water quality, soil health, and human health; 3) Engage the scientific community to facilitate the development and use of advanced molecular and microscopic tools and translate research findings to generate impacts in broader communities. This project will benefit agricultural and environmental science community by advancing analytical tools and methodology. Improved understanding on soil processes and soil health and development of effective management practices will be beneficial to agricultural production, the environment, and the public.

 

Statement of Issues and Justification

Climate and environmental changes are associated with more frequent extreme events, including flooding, drought, heat waves, sea level rise, and saltwater intrusion in coastal regions. These events profoundly impact agricultural and non-agricultural areas, e.g., soil biogeochemical processes, including the mobility and cycling of essential nutrients and toxic contaminants. Further, by 2050 food production must increase by 60% to support the demands of a rising global population, placing already stressed agroecosystems under challenging conditions as essential agricultural resources like fertilizers, water resources, and farmland are becoming more expensive and complex to manage sustainably. One of the most promising avenues for making significant technological advancements in agricultural and environmental sciences is through fundamental research on physical, chemical, and biological processes occurring in both natural and managed ecosystems (Augustine and Lane, 2014; Huang et al., 1998; Sposito et al., 1992).

The fate and availability of plant nutrients and environmental toxins are influenced by their interactions with soil matrices composed of complex aggregates. These aggregates, formed by primary particles such as silt, clays, microbes, and nanoparticles with tens of micrometers or less diameters, create complex inter- and intra-aggregate interfaces and porosity. These structures control chemical reactions, biological activities, and physical transport within the soil. Due to the complexity of soil systems, understanding the mechanisms governing the transport and retention of chemicals can be challenging. Gaining a mechanistic understanding of chemical reactions in soils that control nutrient and contaminant mobility, bioaccessibility, and bioavailability requires using advanced spectroscopic and microscopic instruments to probe molecular- and pore-scale phenomena. This approach is akin to our current capabilities in characterizing microbial communities in natural and engineered systems by analyzing genetic materials using next-generation sequencing, quantitative PCR, and bioinformatics. Using advanced molecular tools, we will gain fundamental knowledge to advance agricultural systems so as to minimize inputs while optimizing production and economic profitability.

Soil degradation is a global challenge affecting agricultural productivity, water quality, and soil health (Brussaard and van Faassen, 1994; Schrader et al., 2007; Roose et al., 2016; Udawatta et al., 2008a). During soil degradation, soil structure is damaged, thus decreasing soil porosity and altering the transport of water, heat, and gas (Kim et al., 2010; Udawatta et al., 2008a, 2008b, 2012, 2016). Characterization of soil pore parameters and their direct effects on water flow is fundamental to evaluating environmental impacts of land management operations on soil quality and land productivity (Anderson and Hopmans, 2013). Soil structure governs the flow of materials and heat through soil pore space, creating spatial and temporal variations in the material and energy fluxes through soils (Young and Crawford, 2004; Zhang et al., 2005).

Society, in general, will benefit from a better understanding of how soil health improves using integrated soil physicochemical properties and processes and by assessing soil management systems for improved water and nutrient use efficiency in crop production. When we can understand how soil health influences water infiltration, soil plant water availability, and nutrient availability, as well as plant uptake of toxins, we will be better able to predict the influence of soil management on sustainable crop production to ensure crop yield and food safety. The agricultural community will benefit directly from improved soil health from enhanced soil water and nutrient conditions and the production of safe and nutritious food that consumers demand. Scientific knowledge will also be advanced to understand better how pollutants move at the soil pore scale and how that information is integrated into the transfer of contaminants in soil-water-plant systems at the field scale.

Efficient soil water use is critical for grain crops, pasture, biofuel production, and soil health in agriculture. Within soils, biopores are essential to enhancing water infiltration to recharge plant available water and maximize plant available water storage. Thus, studying biopores as influenced by management will assist in recommending sustainable practices for optimizing soil water conditions. Soils are highly heterogeneous regarding their physical properties, including soil structure. Good soil structure, including biopores, enhances water infiltration and decreases surface runoff, thus improving the soil's productive capacity, reducing soil erosion and nutrient loss, and enhancing surface water quality. Gas transport in soils is also highly dependent on soil structure. Using the techniques developed in this project will assist land managers by identifying management techniques that improve soil structure and water conditions.

Soil is a key component of terrestrial ecosystems that store almost twice as much carbon (C) as the atmosphere. Soil C can be easily lost under certain environmental settings or, alternatively, can be increased by appropriate management practices. While substantial progress has been made in deciphering the mechanisms driving soil C accrual, much remains unknown. This deficiency is especially unfortunate in the context of global climate change since soil C accrual strategies effective under new future climate can be efficiently developed only with a better understanding of underlying drivers. A better understanding of the micro-scale processes driving soil C and greenhouse gas production and emissions is key to developing management practices optimal for soil health and environmental sustainability.

Soil productivity and soil health critically depend on nutrient conditions in soils. Although phosphorus (P) is a limiting nutrient in many ecosystems, anthropogenic inputs have accelerated terrestrial P flows approximately three times their background rates through the application of synthetic and animal based-fertilizer (Carpenter et al., 1998; Howarth et al., 2002; Liu et al., 2008; Smil, 2000). Long-term application of fertilizers has resulted in the accumulation of P in intensively managed agricultural soils in the US (Foley et al., 2005; Gronberg and Arnold, 2017; Sims et al., 1998). The excess P in soils can be discharged into surface water, resulting in algal bloom, eutrophication, and the Development of hypoxic zones (Diaz and Rosenberg, 2008; Dodds, 2006). Thus, various management practices have focused on control technologies (e.g., vegetated buffer strips and cover crops) in key watersheds in each state. However, there is great uncertainty about the transport of dissolved, colloidal, and particulate P across landscapes under extreme weather conditions.

Particulate matter in the air of rural and agricultural regions can come from primary sources of direct emissions and secondary sources from reactions of gaseous chemicals in the atmosphere. To understand the context of agricultural emissions contributing to particulate matter in the atmosphere and the effects of particulate matter on agricultural production, air quality, human health, and climate, more information is critically needed on the primary and secondary particle sources. Some of our members focus on studying particulate matter in the air, including airborne microorganisms. Investigation of the presence of airborne microorganisms (bioaerosols) in the ambient air is of interest due to their environmental and human health effects (Burge, 1990; Douwes et al., 2003). Bioaerosol-related issues could be especially acute in agricultural environments, where high airborne microorganism concentrations could be encountered. The presence of bioaerosols in agrarian environments differs from their presence in other environments because bioaerosols are known to transmit plant diseases (Parker et al., 2014; West and Kimber, 2015) and, likely, animal diseases. Additionally, airborne microorganisms can carry antibiotic-resistance genes, thus contributing to the spread of antibiotic-resistant bacteria and the proliferation of antibiotic resistance (Yan et al., 2022).

A common thread that runs through much agricultural and environmental research is the importance of understanding processes that operate on different spatial and temporal scales. The current scientific literature supports the technical feasibility of applying advanced analytical methods to a wide range of sample sizes and chemical compositions. Utilizing a combination of techniques to fully characterize natural systems and relate these properties to behavior in complex systems has become increasingly important and successful. To do this, NC1187 is a workgroup of scientists utilizing advanced analytical tools to investigate particles in air, soil, and water systems.

Significant advances in technologies related to spatially resolved microscopic and spectroscopic molecular characterization methods have resulted from advances in optics, focusing devices, and detectors because of the greater availability of high-brilliance synchrotron facilities worldwide (Fenter et al., 2002; Kelley et al., 2008; Lombi and Susini, 2009; Singh and Grafe, 2010), such as the Advanced Photon Source (APS), the Advanced Light Source (ALS), Stanford Synchrotron Radiation Lightsource (SSRL), the National Synchrotron Light Source II (NSLS-II) and others around the world. At these facilities, spatially resolved synchrotron-based X-ray fluorescence (XRF) and X-ray absorption fine structure (XAFS) spectroscopy provide microscopic and molecular level information on soil systems not previously available using other techniques. While there exists a variety of micro-analytical techniques that have long been used in these disciplines, synchrotron-based spatially resolved XRF, XANES, scanning tunneling X-ray microscopy (STXM), EXAFS spectroscopy, and X-ray diffraction (XRD) are emerging as essential methods that complement characterization by traditional techniques.

Advanced analytical techniques are also available at national labs, such as the Environmental Molecular Science Laboratory (EMSL), a national scientific user facility at the Pacific Northwest National Laboratory with several instruments for studying soils and sediments. Specialized instrument facilities, funded by the National Science Foundation and located at universities around the country, also have instruments that can assist in meeting the basic research needs of NC1187.

Long-term solutions to natural resource utilization and management require basic research focusing on understanding the fundamental processes that drive innovations in food, energy, and water science. To address the modern challenges of food production and decrease use of water and energy resources, NC1187 will pursue the following objectives:

Objective 1: Develop advanced molecular and microscopic tools to elucidate fundamental processes governing particulate matter in the environment.

Objective 2: Characterize and quantify the physical, chemical, biological, and morphological properties and processes of particulate matter over a wide range of spatial and temporal scales in a changing climate and the resulting impact on ecosystem health, food, and energy production, climate change, air and water quality, soil health, and human health.

Objective 3: Engage the scientific community to facilitate the development and use of advanced molecular and microscopic tools and translate research findings to generate impacts in broader communities.

The demand for increased food production, water, and securing the environment's health has created a research challenge for the current and next generation of scientists. To meet these demands, NC1187 members will use advanced instruments to do molecular and microscopic-level analyses, collaborate to train members, and make these tools available for such analysis.

This multistate project provides several advantages. First, the focal point of this project, i.e., integrated modern instrumentation, including synchrotron microspectroscopy, demands extensive cooperation among members: sharing the experience with specific facilities and analytical techniques, and sharing disciplinary expertise (soil, water, and air chemistry, microbiology, physics, etc.). Second, this project will promote the use of synchrotron sources to push the envelope in terms of micro-spectroscopic characterization of particles and will integrate synchrotron techniques with other state-of-the-art tools provided by national labs and universities (Coward et al., 2019; Pitumpe Arachchige et al., 2018 & 2024; Sowers et al., 2018). Third, project participants will share samples and data for multiple analyses and will work to produce an integrated investigation sample set or experimental site. Working within a multistate research group while performing the work under one or more objectives offers a unique advantage to our members through formal and informal collaborations and continuous information and knowledge sharing.

In the past, synchrotron research by soil scientists primarily focused on legacy contaminants, i.e., metal(loids). There are many opportunities now with micro-focused techniques to study elements like carbon and organic matter dynamics and nitrogen dynamics. These are critical in addressing global climate change, transformations, and the fate of phosphorus and other macro- and micronutrients in soils. This approach will link more basic and applied soil science, particularly in nutrient management, climate change, and soil health. The members have already established an excellent record of multistate collaboration and technological information sharing, and the members anticipate continuing their collaborations.

This project will enhance our ability to assess the impact of micro- and submicron-sized particles on agricultural and natural ecosystem processes by elucidating links between particulate (physical, biological, and chemical) properties and their role in those systems' sustainability, productivity, and health. Research activities coordinated under this project will result in a knowledge base of particulates' physical and chemical properties related to agriculture production and evaluations of particulates' rate and transfer mechanisms through the environment, causing environmental degradation. This project will also improve our ability to monitor exposures to airborne particulates, including microorganisms, in various environments. Improved understanding of particulate and bioaerosol sampler performance and guidelines regarding their integration with molecular analysis tools will enable more accurate exposure assessment. A better understanding of the fate and transfer of contaminants and exposure assessment of airborne particulates will lead to informed decisions and better protective and control measures, thus contributing to protecting resources and public health.

Related, Current and Previous Work

A CRIS search was conducted. Though other multistate projects examining soil, agriculture, and human health exist, there is no overlap with this project. None of the current projects focuses on investigating the fundamentals of particulate matter cycling and reactivity using advanced analytical techniques. Projects with some aspects broadly similar to the proposed NC1187 activities include:

W5188: Soil, Water, and Environmental Physics to Sustain Agriculture and Natural Resources

W5170: Beneficial Use of Residuals to Improve Soil Health and Protect Public and Ecosystem Health

Members of this project are applying a wide range of analytical tools to elucidate mechanisms of physical and chemical protection of carbon in soils, redox cycling of iron, cycling and reaction pathways of nitrogen, phosphorus, and other nutrients in soils, micro-scale hotspots of greenhouse gas production within soil pore structure, colloid transport through the soil, removal and in situ stabilization of soil contaminants, the effect of climate change on soil structure, storage and transport of soil water and contaminant mobility, detection of dense non-aqueous phase liquids (DNAPLs) in geomedia, testing a few different wastewater treatment processes that will supply unrestricted reuse water, will recycle nutrients, and will sequester carbon in soils to help mitigate greenhouse gas increases in the atmosphere, time-resolved simultaneous measurement of atmospheric aerosols, and fate and effects of airborne particulates.

Several members of our group (Anderson, Gimenez, Kravchenko) are working on various aspects of imaging and quantification of pore systems in soils. Computed microtomography (m-CT) can be viewed as a technique in soil studies that enables the examination of local variation (μm-scale). In contrast, conventional computed tomography (CT) enables examination at a mm scale (Anderson and Hopmans, 2013). Dr. Anderson's group investigated the effect of cover crops on soil structure using m-CT. Overall, the micrometer scale determination of geometrical pore network characteristics showed added benefits of cover crop use compared with no cover crop; thus, the use of CC can be beneficial in improving soil pore networks (Alagele et al., 2023; Rankoth et al., 2022). We believe that experiments and simulation or building of models must go hand in hand to better understand pore-scale soil processes and their relationships to environmental and production benefits.

Some members of our group (Hettiarachchi, Kravchenko) have studied the role of physical and biochemical interactions at the micro-scale in governing soil's contribution to the global cycling of carbon and nitrogen. The strength of this research lies in our ability to obtain direct spectromicroscopic evidence in situ, in free soil micro aggregates in their native state directly while preserving the aggregate microstructure (Pitumpe Arachchige et al., 2018 & 2024). They found that less recalcitrant organic carbon species were preserved within microaggregates, some stabilized with their original morphology. Strong organo-mineral associations and no-till promoted stabilization of less recalcitrant organic carbon were also evident. Microbial-derived C was found in manure-compost-added soil microaggregates suggesting the contribution of organic amendments in facilitating microbial diversity and soil C storage. Kravchenko team identified water absorption by decomposing residues to be one of the primary conditions defining the occurrence and strength of micro-scale hotspots of N₂O production (Kravchenko et al. 2017; 2018a; 2018b; Kravchenko and Guber, 2017). While the chemical composition of the plant residues and soil moisture and texture have long been known to influence N₂O production and emission, Kravchenko's team also identified additional never-before-considered factors that affect the magnitude of N₂O production and emission from such hotspots. These factors are the plant residue's soil pore structure and physical characteristics, e.g., porosity (Kravchenko et al., 2018a; Kutlu et al., 2018). The findings will improve accuracy in modeling and predicting N₂O emissions from agricultural soils. They will suggest new management strategies for reducing N₂O emissions. Dr. Kravchenko's group is also exploring the role of soil structure in protecting and sequestrating soil organic carbon and improving soil health. The recent focus is the contribution of Mn and Fe to the interactions between soil structure and soil carbon. The work relies on joint analyses of soil pore structure via X-ray computed micro-tomography with XRF Mn and Fe mapping and XANES spectroscopy to explore the spatial distribution patterns in Mn oxidation states in intact soils.

Phosphorus use efficiency is poor (10-30% in the first growing season) in many acid and calcareous soils due to fixation reactions between the orthophosphate anion and various forms of Ca, Fe, or Al that limit the nutrient's availability to plants. Similar issues exist for micronutrient fertilizers, as including micronutrients in commercial micronutrient fertilizers is a common practice worldwide for practical reasons. The cost of conventional phosphorus and micronutrient fertilizers yield loss, and environmental issues due to their inefficient utilization are considerable. Therefore, it is essential to find new application methods or novel fertilizer technologies that can increase the efficiency of P (Weeks and Hettiarachchi, 2019) and micronutrient acquisition (Chahal et al., 2023). Our members will continue to investigate the novel fertilizer technologies for both N and P that will enable nutrients to be released slowly and/or diffuse further to furnish more plant-available nutrients while preventing environmental losses.

Several group members (Arai, Strawn) focus on P transport mechanisms in the agricultural landscape. One of the biggest challenges for improving farm productivity and environmental sustainability is accurately predicting the amount of P transported to surface waters in a particular system. The P loading problems to surface waters occur because nutrient management plans do not correctly account for the P loading potential of soils and the availability of P for offsite transport. In the new project, our members will investigate the speciation of soil P, transport of soil solution and particulate P, and recovery of P for use as fertilizers for wastewaters and soil wind erosion. Results will provide new knowledge to improve water quality and agricultural nutrient use efficiency.

Several members in our group (Hettiarachchi, Schwab, Zhang) are using advanced spectroscopic techniques to study redox processes in soil using advanced analytical techniques, including various synchrotron-based spectromicroscopy techniques. Redox cycling of iron (Fe) in soils between Fe(II) and Fe(III) is linked to carbon and energy flow, as well as the movement and bioavailability of most contaminants and nutrients. Studies have also shown the clear role of Fe oxides in sequestering native soil arsenic (As) and other soil contaminants mobilized under reduced conditions (Galkaduwa et al., 2018; Wu et al., 2015). These results are a promising step in proving the existence of various Fe oxyhydroxides in reducing soil and their impact on contaminant and nutrient cycling in the environment.

Members of this group (Anderson, Gimenez, Zhang) have also been involved in studies on the fate and transport of antibiotics resulting from land application of animal waste, considering that they constitute a significant concern in agroecosystems and associated water resources. Past work has evaluated the effects of vegetative buffers on adsorption sites for antibiotics and the influence of these adsorption/desorption processes on transport (Chu et al., 2010; Chu et al., 2013). The proposed work will focus on these transport mechanisms for similar pollutants.

To connect soil and water contamination with food production, several members of our group (Feng, Hettiarachchi, Zhang) are working on the uptake of pharmaceuticals and metals by vegetables, in-plant metabolisms of pharmaceuticals, the changes in ARGs and bacterial community in lettuce and soils due to pharmaceutical exposure, the deposition and removal of ENPs on fresh produce surfaces (Bhalsod et al., 2018; Chuang et al., 2018; Chuang et al., 2015; Li et al., 2018; Li et al., 2022; Shen et al., 2021; Gunathilaka et al., 2023) as well as uptake, deposition and removal of common trace elements in urban soils (Attanayake et al., 2015; 2017). Our members have also investigated the effect of biochar, compost, and exceptional quality biosolids amendment on contaminant behaviors in soil, water, and plant systems, including contaminant sorption and plant uptake of contaminants (Attanayake et al., 2015; 2017; Liu et al., 2019; Wang et al., 2019a). Exceptional quality biosolids and biochar amendment in soils have many agronomic and environmental benefits such as increasing soil organic carbon (SOC) levels, improving soil health and crop productivity, mitigating greenhouse gas emissions, and reducing contaminant bioavailability (Ahmad et al., 2014; Alvarez-Campos et al., 2018; Alvarez-Campos and Evanylo, 2019; Attanayake et al., 2015; Geesley et al., 2011; Jeffery et al., 2011; Kookana, 2010; Laird, 2008; Laird, 2008; Lehmann et al., 2006; Zhu et al., 2017). Therefore, studying how these soil amendments influence soil physicochemical and biological characteristics is important to better achieve intended ecosystem services.

Our members have published multiple contributions regarding developing and analyzing new and existing bioaerosol samplers, including using electrostatic methods for improved bioaerosol collection (Yao et al., 2005; Yao and Mainelis, 2006). They demonstrated the feasibility of an electrostatic collector where the use of a superhydrophobic substance ("Lotus leaf" type) and specially-shaped electrodes allows efficient bioaerosol capture into liquid droplets as small as 5 µL (Han and Mainelis, 2008; Han et al., 2010; Han et al., 2011). This device was further developed and applied in the field (Han et al., 2015). They also successfully explored the application of electrostatic phenomena for passive bioaerosol collection (Therkorn et al., 2017a; Therkorn et al., 2017b). In related work, they also developed a concept of a personal bioaerosol collector based on electrostatic principles (Han et al., 2017; Han et al., 2018). Among other advances, a research protocol for rapidly characterizing bioaerosol sampling devices using adenosine triphosphate (ATP)-based bioluminescence was also developed (Seshadri et al., 2009). Multiple studies comparing bioaerosol samplers were also conducted.

Atmospheric aerosols impact our climate through direct interaction with sunlight and influence clouds' formation, lifetime, global extent, and brightness. Secondary organic aerosol (SOA), formed through the atmospheric oxidation of volatile organic compounds (VOCs), comprises a substantial fraction of this atmospheric aerosol. Globally, the burden of secondary organic constituents is much more significant than that of directly emitted primary organic particulate matter. This is observed in both rural and urban areas. Yet their formation pathways are only just now beginning to be understood. Time-resolved data at the molecular level for organic matter and its volatile, intermediate volatility, and semi-volatile vapor phase counterparts is critical for understanding the sources and chemistry of atmospheric aerosols. Time-resolved simultaneous measurement of these compounds at the molecular level enabled by the new instrument under Development in this ongoing project by the University of California, Berkeley (Goldstein's Group), will provide valuable insights into the role of atmospheric aerosols in global climate and regional air pollution. Such data will aid in evaluating the role of biogenic emissions, assessing the importance of a wide variety of anthropogenic emissions in the urban environment, understanding the global background, and elucidating the processes transforming organic vapor emissions into particulate organic matter. When linked to fundamental studies of hygroscopicity and nucleation activation, data at the compound level will help predict the effects of organic aerosols on clouds and, ultimately, on the radiation balance. Such understanding of organic aerosol sources, atmospheric processes, and effects is necessary for the development of effective pollution reduction strategies and for elucidating the role of aerosols in radiative forcing of earth's climate, thus providing the scientific basis necessary to support models of anthropogenic impacts on climate and sound environmental policy decisions.

The members of this multistate project group have collaborated well together in the past. For example, Dr. Hettiarachchi (KSU) worked together with an NC1187 group member in Texas and his team (Texas A&M, Paul Schwab, and a graduate student, Aditi Pandey) on analyzing and interpreting collected STXM-NEXAFS data on Martian analog soils. Our group organized an in-person annual meeting in conjunction with the 3rd International Pan American Light Sources for Agriculture (July 12-14) at Cornell University. Following the meeting, Michigan State University (Kravchenko) initiated collaboration with Virginia Tech (Possinger), focusing on the role of metals (Mn and Fe) in processes leading to soil C cycling and soil health improvements. Regarding collaborative publications, Dr. Strawn from the University of Idaho and Hettiarachchi from Kansas State University collaborated on a review of trace elements in the environment (Strawn and Hettiarachchi, 2021). Dr. Zhang co-authored a review paper on fate and transport in environmental quality with authors from multiple States (Pachepsky et al., 2021). Several members of the multistate group organized a symposium at the 2021 annual meeting of the Soil Science Society of America with talks on rates and mechanisms of soil chemical processes important for solving society's grand challenges, including climate change, soil health, environmental risks, and food safety and security. In 2024, at the annual meeting of the Soil Science Society of America, several members of the group organized a symposium on advanced analytical techniques and their application to soil and environmental chemistry (Hettiarachchi, Possinger and Strawn).

This multistate project aims to utilize and integrate modern analytical instruments and techniques to provide information on physical properties, chemical processes, and biological processes occurring in soil systems. This includes: a) development of knowledge to improve application of synchrotron tools to assess complex matrices; b) development of sample collection and sample preparation methods; c) continued development of faster analytical methods that will allow us to do more comparative investigations of complex environments and automated in-situ instrumentation for field-based organic chemical composition measurements of particulate matter and semi-volatile gases; d) continued development of analytical and data analysis methods for C, N, P, Al, Ca, Fe, trace elements, and organic chemicals; e) education of participants and the wider community of agricultural researchers in the use and availability of these techniques and instruments; and f) interaction with national laboratory facilities at Argonne, Brookhaven, Stanford, Berkeley and Hanford to promote their use in the agricultural sciences and assist in the development and acquisition of equipment and expertise relevant to the agricultural science community. To achieve these goals, three objectives will be pursued.

Objectives

1. Develop advanced molecular and microscopic tools to elucidate fundamental processes governing particulate matter in the environment.
   
2. Characterize and quantify the physical, chemical, biological and morphological properties and processes of particulate matter over a wide range of spatial and temporal scales in a changing climate and the resulting impact on ecosystem health, food and energy production, climate change, air and water quality, soil health, and human health.
   
3. Engage the scientific community to facilitate the Development and use of advanced molecular and microscopic tools and translate research findings to generate impacts in broader communities.
   

Methods

Objective 1: Develop advanced molecular and microscopic tools to elucidate fundamental processes governing particulate matter in the environment.

The past decade has witnessed significant advances in technologies related to spatially resolved X-ray spectroscopic techniques, both because of advances in X-ray optics, focusing devices, and detectors and because of the greater availability of high-brilliance synchrotron facilities worldwide. This includes the Advanced Photon Source (APS) at the Argonne National Laboratory, the Advanced Light Source (ALS) in Berkeley, CA, the updated Stanford Synchrotron Radiation Lightsource (SSRL), and the National Synchrotron Light Source II (NSLS-II) at the Brookhaven National Laboratory. The result is that spatially resolved synchrotron-based X-ray fluorescence (XRF), X-ray absorption near edge structure spectroscopy (XANES), and extended X-ray absorption fine structure (EXAFS) spectroscopy have become mainstream techniques in several scientific disciplines and are providing molecular level information not previously available using other techniques. While there exists a variety of micro-analytical techniques that have long been used in these disciplines, synchrotron-based spatially resolved X-ray fluorescence spectroscopy (XRF), XANES, EXAFS spectroscopy, X-ray diffraction (XRD) as well as scanning transmission X-ray microscopy (STXM) are important methods that complement characterization of particulates by traditional techniques, as well as by other new methods, such as spatially resolved luminescence, FTIR, Raman spectroscopy, and CT scanning aided with 2D soil zymography. The reasons for this are the elemental specificity, low detection limits, non-destructive nature of the measurement, the ability, in many instances, to examine samples in situ, and the ability to extract information on valence states and on specific bonding environments or molecular forms of target elements in complex matrices. One of the greatest challenges for using spatially resolved microspectroscopy is sample preparation. This multistate group will work collaboratively to develop a knowledge base on the sample preparation methods to avoid artifacts. For instance, our team members are planning a collaboration to determine the ideal sample preparation of natural materials, such as soils, for analysis at synchrotron facilities.

While there is growth in the number of micro- and nano-probe instruments at synchrotron facilities worldwide, the scientific user base for these tools in Earth and environmental science is still underdeveloped. Environmental biogeochemists continue to demand access to these techniques. It is becoming increasingly challenging to obtain beamtime to conduct research using newer and/or less common techniques and beamlines, such as STXM-NEXAFS (Hettiarachchi et al., 2017). Due to the scarcity of instrument time and challenges specific to environmental samples, fully developed research programs are limited in which statistically responsible sampling and/or data collection can be employed. An additional and more problematic issue for new synchrotron users is gaining the knowledge required to conduct high-quality measurements and analyze, interpret, and publish meaningful data. We will continue to facilitate training of new instrument users to synchrotron-radiation expertise and play a key role in helping these techniques fulfill their promise for high-quality, high-impact environmental research over the next decade. The role of this project in these activities is facilitated by the current active involvement of members of this multistate project in research at synchrotron facilities at the Canadian Light Source, Brookhaven, Argonne, and Lawrence Berkeley National Laboratories, and the Stanford Synchrotron Radiation Light Source. Yuji Arai serves on the proposal review panel at the Advanced Photon Source. Ganga Hettiarachchi and Daniel Strawn are proposal reviewers for Stanford Synchrotron Radiation Light Source and Canadian Light Sources.

Objective 2: Characterize and quantify the physical, chemical, biological, and morphological properties and processes of particulate matter over a wide range of spatial and temporal scales in a changing climate and the resulting impact on ecosystem health, food, and energy production, climate change, air and water quality, soil health, and human health.

It is now widely accepted that specific information on particulate matter's composition, surface characteristics, and morphology is a prerequisite to a comprehensive understanding of toxic elements and nutrient behavior in soils and sediments. For example, phosphorous interacts with oxide surfaces to form strong chemical complexes that may reduce its availability to plants or transport to ground and surface waters. On the other hand, colloidal transport by wind or water may hasten the mobility of phosphorous while removing it from a cropping system. The nature of the P-soil interaction, the particle itself, and its susceptibility to movement must be determined. This cannot be done by any one instrument or investigator. We will apply spectroscopic, computational, and analytical methods to particles in complex systems such as soils and sediments under environmentally relevant conditions. Members of this project (e.g., Arai, Strawn, Hettiarachchi) plan to use novel synchrotron-based X-ray absorption and X-ray fluorescence spectroscopy to speciate phosphorus in soils.

Some of our members will contribute towards Objective 2 by integrating modern analytical instruments and other techniques (Kravchenko, Anderson, Mainelis). One essential instrumental tool they use is X-ray computed micro-tomography scanning (CT). Our members work in close collaboration with colleagues from the APS at Argonne National Laboratory in Argonne (beamline 13-BM-D of the GeoSoilEnvironCARS) and with other researchers at their universities for conducting X-ray CT scanning. The overarching goal of their work is to characterize micro-scale spatial patterns in soil physical characteristics. Specifically, they use the scanning tools to describe soil pore structure, i.e., pore size distribution, porosity, pore connectivity, and tortuosity. The key research questions they aim to answer is (1) how long-term implementation of different land use and management practices influences soil pore structure; (2) how properties of the pore structure affect processes governing soil carbon storage and protection, and production and emission of greenhouse gases, CO₂, and N₂O from the soil; and (3) how soil pore structure influences soil microorganisms and their functioning.

Another research task being investigated, which includes CT scan and X-ray tomography, is the effect of desiccated soil cracks in the partition of evapotranspiration (Guzman and Chu). However, this has been challenging due to the limited available devices with sufficient energy to scan large experimental soil columns. Desiccated soil cracks are part of the soil structure dynamics expected to develop deeper, favoring the transport of heat and pollutants, and water transfer to the atmosphere, especially during temperature persistence events. The critical question is how desiccated soil cracks as a soil structure modifier can be characterized and represented across scales in a mechanistic manner to include environmental forcing and human intervention.

Another technique our members are integrating with CT scanning is 2D soil zymography. Zymography enables obtaining micro-scale maps of spatial distribution patterns for several extracellular enzymes on intact soil surfaces. During zymography, a membrane saturated with an enzyme-specific fluorogenic substrate is placed on the surface of a soil sample. Upon contact of the substrate with soil enzymes, a fluorescent product (e.g., MUF: 4-methylumbelliferone, or AMC: 7-amido-4-methylcoumarin) is released, and its presence on the membrane is then detected under UV light. The fluorescing pattern on the membrane reflects the spatial distribution of active enzymes on the soil surface. Zymographic measurements on the soil samples subjected to previous CT scanning enable associations between the presence of soil pores, particulate organic matter, and roots with relative enzyme activities, which can be used to better understand the microbial activities and distributions in soil.

Some members of our group will continue to develop electrostatics-based samplers for bioaerosol collection, more specifically, further development and conversion of these samplers to portable, battery-operated devices (Mainelis). The experimental setup and procedural details of various sampler testing have been published in the literature, including by our group (Han et al., 2010; Han et al., 2011). In the initial phase of the work, the experiments will be performed in a laboratory with specifically aerosolized microorganisms. Once the laboratory trials are successful, the testing will move to the field. Here, we will take advantage of the unique resources the multistate grant mechanisms offer: access to the participants' sites. Specifically, the battery-operated electrostatic samplers will be tested in various agricultural environments, and access will be secured through collaborative efforts with multistate group members.

Several group members will work on measuring and characterizing particulate P in fertilized soils, tile waters, surface runoff, snow melt, etc., at farms with various cropping systems and agricultural management (Arai, Hettiarachchi, Strawn). This will be done immediately following fertilization, during the growing season, or during high flow events (e.g., typically March through May in the Midwest), where they can obtain liters of water for this in-depth chemical analysis using novel techniques (e.g., P-31 NMR, P K-edge XANES), in addition to performing other wet chemical analyses (e.g., total P, dissolved reactive P, P fractionation) as well as traditional particle characterization (e.g., elemental association, morphology) using Transmission Electron Microscopy (TEM) and or SEM techniques at their home institutions.

Many of our group members will also study the impacts of extreme events on soil biogeochemical processes, including contaminant (metals, metalloids, and nutrients) mobility and cycling in agricultural and non-agricultural areas. Soil and sediment samples will be collected from contaminated sites (e.g., urban sites, coastal sites, and along a salinity gradient that has been impacted by high inputs of fertilizers). Standard methods will characterize the samples for physicochemical and mineralogical properties and salinity. Additional characterization, including sequential extractions, will be conducted on the samples to gain insights into metal(loid) and nutrient associations with different soil and sediment components and to complement synchrotron-based microfocused X-ray fluorescence (XRF) and X-ray absorption (XAS) spectroscopic analysis.

Some of our members will perform an array of experiments to understand interactions of engineered nanoparticles, antibiotic resistance genes (ARGs), antibiotic-resistant bacteria (ARB), and bacteria, metals, and per- and per- and poly-fluoroalkyl substances (PFAS) with plants and develop potential mitigation strategies, including growth experiments in greenhouses using model vegetable crops (e.g., lettuce, spinach, radish, and carrots) or in field (Zhang). Exposure and health risks to humans due to contaminated food crops will be evaluated.

Another group of our members will use µ-CT alone or other techniques to get quantitative information on soil microstructure, which is required to improve our understanding of various soil processes (Anderson, Kravchenko). Soil cores for these studies will be collected from selected soil management treatments, including cover crop management systems and agroforestry buffer systems. 

A few members of our group will also focus on recovering and recycling energy and nutrients, including carbon and water, from waste and wastewater (Hettiarachchi, Strawn). They will test the hypothesis that innovative wastewater treatment technologies can produce the right water from different sources while recovering nutrients, producing soil amendments for crop production, and protecting the environment. They will conduct greenhouse and field research on soil factors affecting nutrient and potential contaminant uptake by selected crops grown in the Inland Pacific Northwest and Midwest regions. They will research how waste, recovered products/coproducts, and treated waters affect nutrients and contaminant mobility and bioavailability and plan to use various analytical tools (e.g., XAS, XRF, XRD, FTIR, and UV/Vis spectroscopy) to elucidate speciation nutrients and contaminants in soils and plants.

Objective 3: Engage the scientific community to facilitate the Development and use of advanced molecular and microscopic tools and translate research findings to generate impacts in broader communities.

We plan to organize short summer courses on advanced analytical methods open to the scientific community. Also, periodic webinars to share the latest findings can be valuable in engaging a broader audience. National and international scientific conferences are great venues for organizing sessions to showcase our work and exchange with other scientists in this area. Extension and outreach will be carried out to translate our scientific findings into practical solutions that will benefit farmers, growers, and other stakeholders.

We also plan to organize workshops on advanced analytical methods and data analysis workshop open to the meeting attendees at the ASA/CSSA/SSSA Annual Meetings each year. Invited beamline scientists and NC 1187 members will share there knowledge and experiences with attendees.

Measurement of Progress and Results

Outputs

• Presentations, organizing special symposiums and topical sessions by group members at national/international meetings: These include those of the American Chemical Society, American Geophysical Union, European Geophysical Union, Goldschmidt Conference, American Society of Agronomy/Crop Science Society of America/Soil Science Society of America, Clay Minerals Society, American Association of Aerosol Research and other relevant meetings.
• Publications in peer-reviewed and high-impact journals in the field of particulate science such as Environmental Science and Technology, Water Research, Langmuir, Soil Science Society of America Journal (SSSAJ), Journal of Environmental Quality (JEQ), Geochimica et Cosmochimica Acta, Journal of Geophysical Research, Atmospheric Chemistry and Physics, Proceedings of the National Academy of Sciences, Science, and other relevant journals.
• Proposals submitted to private, federal, and multinational funding sources, such as AFRI, DOE, DOD, EPA, NIEHS, and NSF. Project members could submit joint proposals, including collaborative projects, multi-investigators, and interdisciplinary projects involving non-project colleagues at multiple universities and institutions. There is also the opportunity to collaborate with scientists at national laboratories, e.g., Argonne and Brookhaven, since project members have ongoing research with these investigators on synchrotron-based studies.
• Annual meetings of the NC1187 group that coordinate with tours of national user facilities and/or concurrently at national meetings.

Outcomes or Projected Impacts

• Generate new fundamental knowledge of the properties of micro-and nano-particulates in air, soil, and water. We will examine particles and their spatial organization in agricultural and non-agricultural systems that directly impact the availability of nutrients and water to humans and other living organisms. Microscopic and spectroscopic methods will characterize the locations, bonding mechanisms, and concentrations of C, N, P, K, Fe, micronutrients, meta(loid)s, and contaminant species associated with organic and inorganic particles and their aggregates.
• Microscopic and molecular characterization of particles will be combined with macroscopic studies to link particle properties and those resulting from their spatial organization with environmental behavior.
• We will develop mechanistic models for the partitioning of material at interfaces to link micro- and nano-meter scale processes to mass transfer at larger scales. These models will be applied to environmental and agricultural systems, including interactions between minerals and plant roots, atmosphere and airborne particles, sediment and water, and nanoparticles and microbial cells.
• We will increase the utilization of national laboratories supported by advanced analytical techniques by agricultural scientists. Members will use their contacts and influence on user committees of national laboratories and other service centers to gain access to state-of-the-art instrumentation. In addition, they will inform other members of the availability and capabilities of instrumentation through seminars, email, Zoom meetings, and workshops at the Soil Science Society of America Meetings. Each member will work to educate and encourage colleagues and collaborators at their institutions in the use and means of accessing modern instrumentation, including synchrotron sources and national user facilities.

Milestones

(2025):1. Data generation. 2. Submit the Final Report of NC 1187. 2. Organize and participate in the SSSA International Annual Meetings session entitled "Environmental Particulate Matter in a Changing Climate: Implications for Agriculture and Human Health" to showcase NC1187 multistate group accomplishments. Recruit new members.

(2026):1. Data generation 2. Increase the utilization of national laboratories and collaborations with researchers at the National laboratories 3. Publish a Special Section in a high-impact journal such as SSSAJ or JEQ with selected articles from the previous year's session. 2. Develop and Evaluate New and Existing Relations with User Facilities. Using the special relationship between NC1187 and national synchrotron facilities such as APS as a model, form similar bonds with national labs, including EMSL, the Advanced Light Source (Berkeley), the National Synchrotron Light Source (NSLS), Stanford Synchrotron Radiation Laboratory, and user facilities at universities.

(2027):1. Data generation 2. Increase the utilization of national laboratories and collaborations with researchers at the National laboratories 3. Submission of joint proposals, including collaborative projects and multi-investigator, as well as interdisciplinary projects involving non-project colleagues at multiple universities and institutions.

(2028):1. Data generation. 2. Compilation of information on the properties of micro-and nano-particulate in air, soil, and water 3. Compilation of information on the impact of particles and their spatial organization in agricultural and non-agricultural systems on the availability of nutrients and water 4. Compilations of information on the progress and utilization of mechanistic models for the partitioning of material at interfaces to link micro- and nano-meter scale processes to mass transfer at larger scales.

Projected Participation

View Appendix E: Participation

Outreach Plan

Develop complementary research methods to solve difficult problems in particulate matter characterization and behavior requiring multi-instrumental expertise and availability. We will organize workshops at the ASA/CSSA/SSSA Annual Meetings each year to stimulate this outreach. This will serve to showcase member's skills, interests, and needs. We will organize special sections in JEQ, SSSAJ, or other journals.

Continuation and expansion of relations with national user facilities, including membership on user committees, submission of white papers on user facility needs for agriculture, and interaction with specific facility scientists to develop instruments and methods germane to agricultural research.

Hold workshops, conferences, and short courses that educate agricultural scientists on the availability, application, and use of modern instruments for particulate matter research. Members will present their research at professional society meetings to educate other scientists on the value and capabilities of advanced molecular-scale facilities. Because most group members have State Agricultural Experiment Station (AES) appointments, applied aspects of research that utilize advanced analytical facilities will be reported to constituents (e.g., Ag day, field day) and AES members and administrators.

Together with non-member colleagues, our members will develop or contribute to various educational materials, including extension publications beneficial to educators, regulators, local government decision-makers, the concerned public, other scientists, and stakeholders on the cycling and reactivity of nutrients and contaminants in air, water, and soil. We will continue to convey the science of the implications of particulate matter reactivity and cycling on agriculture and human health through written publications, field demonstrations, workshops, webinars, and direct interaction with stakeholders and clientele.

Organization/Governance

The governance of the multistate project will be handled by three elected positions: chair, vice-chair, and secretary. Each position is assigned specific tasks and is held for two years, with officers rotating through the positions as follows: the chair steps down, the vice-chair becomes chair, the secretary becomes vice-chair, and a newly elected individual becomes secretary. The chair is responsible for organizing the technical program for the upcoming "all hands" meeting. Each official group on the multistate project must present a research report at each "all hands" meeting. If synchrotron funding is secured, each group allocated synchrotron time during a given year must attend the "all hands" meeting and present a research report. The research report will consist of an abstract or oral or poster presentation. If synchrotron funding is secured, the chair will be the official liaison with funding source(s) and synchrotron facilities. The vice-chair is responsible for organizing the logistics for the "all hands" meeting: selecting a venue, reserving rooms suitable for research presentations and the business meeting, arranging housing, etc. The secretary is responsible for all communication with official members of the multistate project. If synchrotron funding is secured, individuals allocate synchrotron time. The secretary is also responsible for preparing the annual report for the multistate project, which will include the proceedings of the "all hands" meeting: minutes of the business meeting, the technical program, and the abstracts of all research reports. All members are responsible for creating links to user facilities and conveying information on availability and capabilities to the membership. Participants are encouraged to acknowledge the NC1187 project with support from NIFA via the Hatch Act with the match provided by the designated states.

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