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 enviornmental change since soil C accrual strategies effective under new future environment 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.

What has been said for P also applies to nitrogen (N). Nitrate contamination in soils, sediments, and surface water, and ground water poses significant risks to human health and global environments. Even though much is known about nitrate degradation in soils, especially via microbiological pathways, a complete solution to this problem has been elusive. One missing piece to the puzzle which could be highly significant is the role played by iron-bearing soil clay minerals in promoting nitrate degradation. The long-term purpose of this aspect of the multi-state project is to devise strategies for on-site or in-stream nitrate remediation using common clay minerals as the catalyst. Because the iron largely remains in the clay mineral it stays in place during the nitrate degradation reaction and can, thus, be regenerated or cycled between its oxidized and reduced states to continue the nitrate reduction process. Clay minerals are everywhere in nature. They make up a significant fraction of soils and of lake, river, and ocean sediments. The goal, then, is to find a way to harness this resource to mitigate the amount of nitrate in agricultural waters that escapes to contaminate non-agricultural environments and purposes.

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, and human health, 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 environment and the resulting impact on ecosystem health, food, and energy production, 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 environmental 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, environmental 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.