Increasing contamination of rice paddies by toxic metal(loid)s from anthropogenic sources threatens food security and public health. In this Perspective, we outline the problem of metal(loid) contamination in paddy soils and propose an activity-centric framework for safeguarding rice production. Approximately 14–17% of croplands exceed safe thresholds for at least one toxic metal(loid), exposing 0.9–1.4 billion people to elevated ecological and health risks. Management strategies that reduce the total mass of toxic metal(loid)s in soils are useful for restoring sites with high metal(loid) concentrations. However, these approaches are expensive and interrupt crop production, making them poorly suited to most in-production rice paddies with low-to-moderate contamination. Activity-centric strategies aim to reduce metal(loid) bioavailability and plant uptake at the soil–water–root–grain continuum, offering a production-compatible alternative. An integrated risk management framework that bridges risk-informed implementation of technologies with localized policy governance to guide regional-scale metal(loid) management is proposed. Further research is needed to develop soil amendment materials and functional synthetic microbial communities that synergistically address metal(loid) contamination and actively contribute to overall soil health and resilience. Toxic metal(loid)s in paddy soils accumulate in rice grains, leading to human health risks from dietary metal exposure. This Perspective describes metal(loid) sources and biogeochemical strategies to reduce metal(loid) bioavailability and uptake, and it proposes a framework for coordinating science, policy and practice in contaminated paddy fields.

On-shore produced water (PW) spills can impair soil quality. To provide a practical tool for evaluating efficacy of PW-contaminated soil remediation, a seed germination test was developed. This research included three experimental phases. In the first phase, seed germination of two native grasses, Brewster sideoats grama (BSG) and Santiago silver bluestem, were investigated in 10-day tests with uncontaminated soils. Based on performance, BSG was selected for subsequent phases. In Phase 2, seed germination tests were performed on field soil spiked with dilutions of PW. A parallel sodium chloride (NaCl) solution prepared at the same chloride concentration as the PW, was tested for comparison. Soil electrical conductivity (EC) was used to characterize salt stress. Results indicated similar seed germination inhibition in PW and NaCl treatments. In Phase 3, exposure to PW and NaCl solutions spiked to field soil was repeated at lower dilutions. Soil exposures to dilutions of a 10 mM solution of a remediation agent, Prussian yellow (PY), alone and combined with PW and NaCl were also tested. In addition to soil EC, free cyanide concentrations were determined to assess potential PY photo-dissociation. Results indicated that PY alone did not inhibit seed germination. Further, addition of PY to PW or NaCl did not increase toxicity with low and variable levels of free cyanide reported in soil. These findings support PY use in soil remedial applications. Despite the wide range of potential contaminants in PW, the primary determinant of toxicity was attributed to salinity under the tested conditions. Further work is needed to assess whether native grass seed germination tests are predictive of revegetation success in the field.

Abstract Forested ecosystems are vulnerable to wildfires which have short- and long-term effects on downstream water quality, including changes to dissolved organic carbon (DOC) transport and disinfection byproduct (DBP) formation downstream, which can be exacerbated by high-intensity rainstorms. To evaluate short-term changes to streamwater composition and characteristics, we sampled three streams feeding into the Cache la Poudre River within the perimeter of the 2020 Cameron Peak Fire before, during, and after the first postfire summer storm season. Streams were distinguished by the proportion of their upstream watershed that burned at moderate to high severity (<25%, 25–50%, or >50%). DOC concentration and turbidity demonstrated storm-driven responses that were greatest in the 25–50% burn area stream. Nitrogen-containing species were enriched in streams during the storm and poststorm periods, depending on burn area. Chlorination experiments measured low molecular weight (C1 – C2) DBPs, where streams from subcatchments with more extensive burns were greater in DOC and DBPs formed across all events. However, DOC released during the storms formed less DBPs on a DOC-normalized basis in all streams. These results demonstrate that DBP formation following wildfire disturbance is primarily driven by storm-mediated increases in DOC loading rather than enrichment in highly reactive pyrogenic material.

In agricultural regions worldwide that are affected by water scarcity, economic activity is often constrained by limited water availability. This paper provides a critical overview of current water-use practices in the agricultural sector, the state of the art in municipal wastewater treatment technologies, and the technical and non-technical challenges associated with advanced treatment and reuse of wastewater effluent for agricultural irrigation in the United States. The reuse of treated municipal wastewater (TMW) in agriculture offers a reliable and locally available water source that can reduce vulnerability to drought and other water supply constraints. It can also deliver significant economic and environmental benefits by lowering energy demand, reducing reliance on river and stream diversions, and decreasing pollutant loads from wastewater discharges. However, effluent from conventional wastewater treatment plants (WWTPs) presents substantial technical and water-quality challenges for agricultural irrigation, primarily due to residual salinity, bacterial and viral pathogens, and contaminants of emerging concern (CECs). Moreover, increasing water scarcity coupled with stricter discharge regulations underscores the need for more comprehensive water-quality characterization of TMW to support its broader adoption while avoiding unintended environmental and public health consequences. Advanced wastewater treatment technologies, combined with improved water-quality monitoring and transparent reporting, are therefore essential to enhancing public confidence and improving marketability of TMW for agricultural reuse.

In recent decades the rise of ultrahigh- and high-resolution mass spectrometry ((U)HRMS) has enhanced our ability to resolve the molecular complexity of dissolved organic matter (DOM) and open the black box linking DOM to the rapidly changing world, including impacts on aquatic systems. In this Review we highlight how direct anthropogenic signatures, and indirect anthropogenic-driven or -impacted processes, shape DOM at the molecular level. For example, changes in heteroatom (N,S) abundance and compound classes, as well as indicator molecular formulae, are linked to land-cover impacts related to agriculture, urbanization, fire and climate change. We also offer insights into areas to further open the analytical window for (U)HRMS, bridging the gap between molecular-level composition and structural analysis of unambiguous molecular tracers for anthropogenic impacts. Finally, we address practical recommendations and areas of need, including standardization and data availability, to further develop (U)HRMS utility for examining anthropogenic impacts on aquatic systems. This Review synthesizes how ultrahigh- and high-resolution mass spectrometry has decoded the molecular-level responses of dissolved organic matter to anthropogenic drivers, providing practical recommendations to advance its utility for examining anthropogenic impacts on aquatic systems.

Well plugging mitigates methane emissions and protects groundwater, yet conventional cement-based methods carry a high carbon footprint. To explore more sustainable alternatives, this study developed a techno-economic analysis and cradle-to-grave life cycle assessment for an orphan well in Colorado, comparing a baseline cement-plugging scenario to one that integrates woody biochar in both the cement slurry (3

Wildland-urban interface (WUI) fires combust both natural vegetation and anthropogenic materials, potentially enriching soils with disinfection byproduct (DBP) precursors that may threaten downstream drinking water quality. To improve understanding of this enrichment, we sampled surface soils (0-5 cm) from 29 residential parcels classified by CalFire as destroyed (n = 11), partially damaged (n = 5), or undamaged (n = 13) following the 2025 Eaton Fire in Los Angeles, California. Soils were leached with simulated stormwater and chlorinated under uniform formation conditions to quantify trihalomethane (THM4) and haloacetic acid (HAA5) formation potential. Destroyed-parcel leachates produced significantly higher dissolved organic carbon (DOC)-normalized THM4 and HAA5 yields than partially damaged or undamaged parcels, despite having leachable DOC within similar ranges. Bromide (Br-) concentrations were elevated in fire-affected leachates and strongly correlated with brominated DBP formation (rho > 0.75, p < 0.05). Using representative runoff factors and measured DBP precursor loadings, we estimated that a WUI fire may produce similar to 3-60 & times; more DBP precursors compared to a wildland fire of the same size. These results provide a field-based characterization of DBP precursor reactivity from WUI fire-impacted soils, demonstrating that anthropogenic combustion residues substantially increase DBP-forming potential and brominated DBP speciation.

Wetlands comprise only 5-8% of land surface but hold 20-30% of estimated soil carbon globally. However, wetlands are also significant sources of greenhouse gases such as methane (CH4) and nitrous oxide (N2O). Disturbances such as wildfires can alter the balance between carbon storage and greenhouse gas production in wetland systems; therefore, it is crucial to understand wetland response and recovery after wildfires. While wildfires are known to significantly impact ecosystem function through changes in soil properties, nutrient cycling, and hydrology, subalpine wetlands remain understudied, with the exception of organic matter-rich peatlands. Though temperature fluctuations regulate microbial processes, it is unclear how seasonal temperature patterns influence wildfire effects. We investigated these interactions in burned subalpine wetland soils in the Medicine Bow National Forest, Wyoming, USA, 1 year after the 2020 Mullen fire. We measured potential rates of carbon dioxide (CO2), CH4, N2O, and DOC production using slurry experiments and flow-through experiments with soil collected from two depths (0-2 and 15-17 cm). Both experiments were conducted at local minimum, mean, and maximum July air temperatures (9, 18, and 27 degrees C). In situ porewater measurements showed that burned wetland areas had higher dissolved organic carbon (84-105 mg/L vs. 65 mg/L), sulfate (2.8-3.3 mg/L vs. 1.4 mg/L), and nitrate concentrations (1.3-1.9 mg/L vs. 0.5 mg/L) compared to unburned wetland areas, particularly in shallow depths (0-12 cm). Slurry experiments revealed approximately 1.3 times higher potential CO2 production rates and fivefold higher N2O production rates, but 2.9 times lower CH4 production rates in burned compared to unburned wetland soils. Flow-through reactor experiments corroborated these findings, showing higher DOC (2-4 & times;), Fe(II) (1.5-2 & times;), and DIC (1.3-1.8 & times;) potential production rates but lower CH4 production rates (0.4-0.8 & times;) in burned wetland soils. The suppression of methanogenesis and enhancement of Fe(III) reduction in these soils suggest altered redox conditions, potentially resulting from changes in organic matter composition, soil exposure, and hydrology following fire. Temperature sensitivity analysis revealed higher Q10 values for Fe(II) production in burned wetland soils (1.60-2.90 vs. 1.57), indicating that fires enhance the temperature response of Fe(III) reduction pathways. These findings provide insights into post-fire biogeochemistry of sensitive subalpine wetland systems, with implications for the global carbon cycle and drinking water quality.

Ecosystem trace gas fluxes (CO2, CH4, N2O) are a critical component of the global greenhouse gas cycle, but uncertainty remains regarding the important mechanisms driving variability across the soil-plant-atmosphere interface. This is due in part to a lack of techniques that can integrate measurements across these interfaces at high spatial and temporal resolution under controllable experimental conditions. To improve upon these experimental techniques, we present a novel approach in which custom-made rhizoboxes, integrated with state-of-the-art planar oxygen (O2) optode sensors and outfitted with water, soil and gas samplers, allow for integration of porewater chemistry, soil microbiology, plant-soil trace gas flux, belowground root dynamics, along with a spatially and quantitatively resolved O2 profile (i.e., planar optode). We demonstrate our experimental design with a case study using three rhizoboxes at controlled water levels, one with soil only and two transplanted with Carex acutiformis, a wetland plant known to transport O2 belowground through the roots (i.e., radial oxygen loss). Our case study clearly illustrates that high spatially and temporally resolved data can be captured using planar chemical sensors and integrated with simultaneous measurements of soil, water, plant and gas variables. We find clear evidence for radial O2 loss, a mechanism occurring at the millimeter scale whereby roots emit O2 belowground. Additionally, we find that plant-soil gas fluxes are correlated to porewater chemistry (i.e., redox potential, pH, O2 concentration), soil microbial relative abundances and planar O2 optode profiles, underscoring the ability of this experimental design to simultaneously monitor a variety of measurement types with minimal disturbance. We find that CO2 uptake from the plants increases significantly (p=0.003, R2=0.78) with belowground root radial O2 loss, indicating a tight coupling between above and belowground plant dynamics. Additionally, the bacterial genus Hydrogenophaga, often associated with denitrification, increased in abundance with a corresponding decrease in N2O flux over time. Finally, we find that conventional porewater O2 measurements provide an inaccurate characterization of soil O2 concentration when compared to planar optodes. Our rhizobox design is a promising strategy for solving fundamental knowledge gaps and mechanisms in biogeochemistry. Our hope is that this will be a useful tool for the community in generating data for improved ecosystem modeling since the setup can be modified to simulate variable environmental conditions and characterize a wide variety of plant-soil systems.

Dissolved organic matter (DOM) plays an important role in microbial electron transfer, influencing elemental biogeochemical cycles and pollutant fate. However, its electron exchange capacity (EEC) can be strongly altered by ferrous {Fe(II)} oxidation-driven adsorptive fractionation and chemical transformations under long-term periodic hydrological fluctuations, which remain largely unexplored. Here, we demonstrate that periodic Fe(II) oxidation progressively increases DOM's EEC by up to 6.2-fold. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) analysis revealed that Fe(II) oxidation increased the low-molecular-weight polyphenolic and highly unsaturated phenolic fractions of DOM by 26.3 and 24.4%, respectively, and enriched quinone and phenolic groups that can mediate electron transfer. Meanwhile, integration of FT-ICR MS data with machine learning identified the changes in molecular weight and O/C ratio as the critical characteristics determining the enhanced EEC of DOM, with newly produced sulfur-containing groups contributing thereafter. Both adsorptive fractionation and reactive oxygen species-triggered oxidative transformation during Fe(II) oxidation determined the increased EEC of DOM, with adsorptive fractionation playing the dominant role. These dynamic DOM changes significantly promoted microbial electron transfer, continuously stimulating iron reduction and concurrent arsenic release in paddy soils, thereby potentially exacerbating toxic metal bioavailability and posing risks to food safety.

Produced water (PW), a byproduct of oil and gas extraction, is traditionally managed using percolation pits and deep well injection, raising concerns over freshwater contamination and induced seismicity while underscoring the need for sustainable solutions. Conventional PW (CPW), extracted from sandstone, offers potential for agricultural irrigation due to lower salts and toxin levels, but requires thorough investigation to ensure its safe, sustainable use. This study examines the effects of irrigation with untreated CPW from the Denver-Julesberg Basin on crop production, soil health, microbial diversity and function, and the plant metabolome using a greenhouse experiment with three irrigation regimes: tap water (Control), 50% diluted CPW (PW50), and undiluted CPW (PW100). Results show that while wheat grain metabolite concentrations, above-ground biomass, and plant height showed no significant differences across treatments, the grain yield was highest in the PW100 treatment. However, PW100 increased soil salinity and pH, which was accompanied by a decline in aggregate stability. Microbial communities in CPW-irrigated soil demonstrated functional shifts, including greater numbers of hydrocarbon degradation genes, suggesting that microbes may help attenuate the impacts of PW hydrocarbons. These subtle ecological changes offer insights into the long-term implications of reusing insufficiently treated PW in agriculture.

Water scarcity presents an ever-growing challenge in global agriculture, with major implications for food security. In the USA, the scale and complexity of the agricultural system magnify these challenges, calling for an integrated and adaptive approach to water management. Hence, we reviewed six key strategies aimed at sustainable agricultural water management — crop distribution optimization, soil management, modern irrigation technologies, water treatment and reuse, reduction of water demand in animal agriculture, and minimizing food loss and waste — identified based on their prominence in recent literature and potential to address water scarcity. In examining these strategies through a multidimensional lens, several challenges have emerged, including gaps in the current structure of incentives, psychological barriers, lack of awareness, reluctance to alter existing farming practices and consumption habits, and insufficient data on the effectiveness of certain water conservation measures. By offering actionable insights into potential areas of improvement, this Review aims to contribute to the ongoing discourse on agricultural sustainability amid changing climate dynamics. A multifaceted approach integrating strategies across food production and consumption is required to advance sustainable water management in agriculture.

Pesticide fate modeling can be used to explore the expected effects of spray timing on pest and beneficial insects. To obtain accurate dissipation predictions, chemical-specific properties including the foliar photodegradation and foliar penetration rates are needed. In this work, photodegradation rates for three insecticides, as both active ingredient alone and in a commercial formulation, were measured. Chlorpyrifos degraded at a rate similar to the dark control so no photodegradation rate was reported. Reported λ-cyhalothrin and indoxacarb photodegradation rates were not significantly different when applied as the active ingredient or formulation. Measured photodegradation rates were incorporated into a pesticide dissipation model and it was evaluated using six field studies conducted on alfalfa fields using the insecticides chlorpyrifos and λ-cyhalothrin. A comparison of the predicted and measured insecticide concentrations in leaves showed good agreement after model optimization. Time-dependent honeybee risk quotients for the 7-day period following insecticide application were then calculated.

With ∼50 million houses in the US located at the wildland-urban interface (WUI) and wildfire activity on the rise, there is a concern that structure fires might be a key source of air pollutants in WUI regions. We report on structure fire experiments performed as part of the Burning Homes And Structural MAterials (BHASMA) project. More than 70 small-scale experiments were performed on 19 different fuels and fuel complexes, representing lumber, processed wood, insulation, carpet, roofing, electrical sheathing, and flooring. More than 20 large-scale experiments were performed on different sizes and packing densities of a fuel test crib composed of lumber, processed wood, gypsum board, and plastics. Emission factors (EFs) for CO2, CO, and CH4 at the same combustion efficiency (CE) did not vary strongly with fuel category or fire scale and were generally consistent with emissions reported in the literature for biomass burning. EFs for PM2.5, organic aerosol, and soot for non-wood-based fuels under flaming conditions were higher than those from wood-based fuels, with soot emissions being 10-fold higher. Overall, we find that structure fires can be similar to vegetation fires for some pollutants (e.g., CO) but not all pollutants (e.g., soot). Our work contributes to the understanding of emissions and environmental impacts from WUI fires.

Significant organic nitrogen (ON) stocks have accumulated in permafrost peatlands over millennia. Climate change is expected to increase peatland thaw, making this ON more susceptible to biogeochemical degradation. However, the interplay between thaw-released N and N cycling remains poorly understood. To elucidate ON composition across a thaw transition (palsa to thaw front to bog), we employed 21 T electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and nuclear magnetic resonance (NMR) spectroscopy. In addition, we performed metatranscriptomic sequencing to evaluate microbial activity changes in N cycling pathways between the palsa and bog. We observed an approximate 10-fold increase in dissolved ON and a significant rise in ammonium concentration between the palsa and thaw front. Additionally, there was a reduction in the peptide-like fraction and an increase in the aromatic fraction of dissolved ON molecules. Dissolved ON concentrations decreased by 73 % between the thaw front and bog, while expression of ammonium-producing genes was significantly higher in the bog compared to the palsa. Our findings highlight the release and rapid compositional shift of ON during thaw transitions. This underscores the need for further studies on thaw-released N to enhance models predicting N cycling and Arctic greenhouse gas emissions.

Oil and gas produced water (PW), may help alleviate regional water scarcity affecting agriculture, but is often rich in salts and organic compounds that constrain agricultural applications. The specific objective is to assess the reuse potential of conventional PW through a comprehensive assessment of chemistry, toxicity, and economics by investigating PW from 18 conventionally drilled wells from sandstone formations in the Colorado Denver-Julesburg Basin. Ammonium, total dissolved solids, boron, sodium, and chloride were all close to recommended guidelines for livestock and crop irrigation and surface water discharge. Diesel and gasoline range organics and polycyclic aromatic hydrocarbons were detected in low concentrations in evaporation ponds compared to oil water separators, suggesting volatilization or degradation of organic compounds. Radium levels were generally low, but select samples exceeded the regulatory 5 pCi/g threshold, categorizing them as Non-Exempt TENORM (Technologically Enhanced Naturally Occurring Radioactive Material) waste. EC50 with Daphnia magna (D. magna) showed little to no toxicity for PW sampled in evaporation ponds in contrast to EC50 values of 12 % at the oil water separator, indicating that volatile organics controlled toxicity. However, the Aryl Hydrocarbon Receptor (AhR) bioassay illustrated toxicity not captured by the EC50 test. After chemical and toxicological analyses, it is clear that treatment is required, which informed our techno-economic assessment (TEA). Current PW volumes result in a treatment cost of $5.38/m3 ($1.42/barrel) by nanofiltration, but a scenario with increased volumes will result in a lower cost of $3.83/m³ ($0.60/barrel). Our chemical, toxicological, and economic assessment indicates that the PW in this study has potential to be discharged to surface water or reused for cattle and crop irrigation.

Antibiotic resistance is posing a major threat to public health, yet there is little effort to quantitatively assess risks associated with antibiotic resistance genes (ARGs), particularly in agricultural soils. We therefore propose a risk assessment framework by integrating metagenomic profiling, quantitative health risk assessments, and machine learning to evaluate distribution and health risks of ARGs in a diverse set of global agricultural soil samples. Based on 985 selected metagenomic samples from diverse agricultural systems, we identified 1745 subtypes from 30 major ARG families, revealing patterns between major agricultural settings. Approximately 1% of global agricultural areas were classified as high-risk, primarily concentrated in regions with intensive farming practices and high antibiotic usage. Our framework enables the identification of risk hotspots which seem to be driven by socioeconomic, climatic, and land use factors. These findings facilitate a methodological advancement for predicting ARG risk through mechanism-driven models, rather than descriptive abundance metrics. The proposed framework will support targeted soil management strategies to mitigate antibiotic resistance propagation in agroecosystems.