Journal of environmental quality最新文献

Concerns regarding per- and polyfluoroalkyl substances (PFAS) and their precursors have driven increased research into their sources, impacts, and mitigation strategies, aiming to reduce their prevalence in the environment. While much of this research has centered on known large sources of PFAS (e.g., military bases, airports, fire training sites, and some manufacturing facilities), there has been increased interest in evaluating the inadvertent introduction of PFAS into agroecosystems from beneficial reuse of treated domestic wastewater for irrigation and land application of biosolids and composts derived from food waste. Additional sources to agricultural fields include the use of PFAS-containing pesticides. These activities raise questions regarding the potential impacts of PFAS introduced to agricultural systems on rural water supplies, soil health, and food safety. This special section contains papers that fall into three categories: (i) source assessment of PFAS in water and wastewater residuals destined for beneficial reuse in agroecosystems, (ii) improved understanding of PFAS fate and transport in agroecosystems following land application of PFAS-containing materials, and (iii) small-scale assessment of techniques that demonstrate promise for mitigating PFAS mobilization in agroecosystems. The work contained in this special section can be used to help guide future decisions related to PFAS guidelines, policies, and regulations in agroecosystems intended to protect human and ecological health.

As global climate change poses a challenge to crop production, it is imperative to prioritize effective adaptation of agricultural systems based on a scientific understanding of likely impacts. In this study, we applied an integrated watershed modeling framework to examine the impacts of projected climate on runoff, soil moisture, and soil erosion under different management systems in Central Oklahoma. The proposed model uses measured climate data and three downscaled ensembles from the Coupled Model Intercomparison Project Phase 6 (CMIP6) at the water resources and erosion watershed to understand the impact of climate change and various climate conditions under three management systems: (1) continuous winter wheat (Triticum aestivum) under conventional tillage (WW-CT; baseline system), (2) continuous winter wheat under no-till (WW-NT), and (3) cool and warm season forage cover crop mixes under no-till (CC-NT). The study indicates that the occurrence of agricultural drought is projected to increase while erosion rates will remain unchanged under the WW-CT. In contrast, climate simulations imposed on the WW-NT and CC-NT systems significantly reduce runoff and sediment while preserving soil moisture levels. Especially, implementing the CC-NT system can bolster food security and foster sustainable farming practices in Central Oklahoma in the face of a changing climate.

Phosphorus (P) loading from tile-drained agricultural lands is linked to water quality and aquatic ecosystem degradation. The RZWQM2-P model was developed to simulate the fate and transport of P in soil-water-plant systems, especially in tile-drained croplands. Comprehensive evaluation and application of RZWQM2-P, however, remains limited. This study evaluates RZWQM2-P in simulating P dynamics using extensive data and assesses the potential of management practices for mitigating P losses. Subsurface drainage and surface runoff flows were monitored at a tile-drained site from 2017 to 2020 in Ohio, and the water flow and P loss data were summarized on a daily basis. RZWQM2-P was calibrated and validated using those observed data and was subsequently used to assess the effectiveness of controlled drainage (CD) and winter cover crops (CC) in reducing P losses. The model satisfactorily simulated dissolved reactive P (DRP) loss from tile drainage on daily and monthly bases (Nash-Sutcliffe efficiency [NSE] = 0.50, R² = 0.52, index of agreement [IoA] = 0.84 for daily; NSE = 0.73, R² = 0.78, IoA = 0.94 for monthly) and total P (TP) loss on a monthly basis (NSE = 0.64, R² = 0.65, IoA = 0.88), but the daily TP simulation was less accurate (NSE = 0.30, R² = 0.30, IoA = 0.59). Simulations showed that winter rye CC reduced DRP by 16% and TP by 4% compared to the base scenario, whereas CD increased DRP (60%-129%) and TP (5%-17%) losses at three tested outlet elevations compared to free drainage. RZWQM2-P can capture P dynamics in tile-drained cropland and is a promising tool for effective P management.

The adsorption process, known for its cost-effectiveness and high efficiency, has been extensively investigated at the laboratory scale for removing per- and polyfluoroalkyl substances (PFAS) from non-conventional irrigation water. However, a syringe filtration step is commonly used when quantifying PFAS removal during this adsorption process, potentially leading to PFAS retention onto the filters and an overestimate of adsorption removal efficiency. Here, we assessed the retention of three prevalent PFAS (i.e., perfluorooctanoic acid [PFOA], perfluorooctane sulfonic acid [PFOS], and perfluorobutanoic acid [PFBA]) on six syringe filters. When filtering distilled deionized water spiked with 1 µg/L and 100 µg/L of each PFAS, we observed the highest and lowest PFAS recovery percentages by mixed cellulose ester (MCE) (0.20 µm, 25 mm; 97 ± 11%, 101 ± 4.8%) and polytetrafluoroethylene (0.45 µm, 13 mm; 61 ± 37%, 80 ± 28%), respectively. Under the initial concentration of 1 µg/L and 100 µg/L, PFOS had recovery percentages of 55 ± 25% and 68 ± 24%, significantly lower than 96 ± 12% and 99 ± 5% for PFOA and 95 ± 8% and 97 ± 4% for PFBA, highlighting the importance of PFAS functional groups. PFAS recovery percentage increased with filtration volume in the order of 80 ± 28% (1 mL) < 85 ± 21% (5 mL) < 90 ± 18% (10 mL). Using MCE to filter treated municipal wastewater spiked with 1 µg/L and 100 µg/L of each PFAS, we found recovery percentages >90% for all three PFAS. Our study underscores the significance of syringe filter selection and potential overestimate of PFAS removal efficacy by the lab-scale adsorption processes.

Residential lawn management often includes fertilizer application to encourage healthy plant growth and support the aesthetic preferences of homeowners and communities. These inputs may negatively impact the environment by increasing nutrient export to aquatic ecosystems via surface runoff or leaching through soil into groundwater. Fertilizer management and nutrient export are of particular concern in karst areas like North-Central Florida, where the underlying karst geology leads to rapid, direct connections between surface and groundwater ecosystems. We quantified nitrogen (N) and phosphorus (P) leaching from residential landscapes in North-Central Florida. We investigated nutrient leaching from landscapes spanning a real estate gradient and across different fertility treatments (no N fertilizer, synthetic mineral fertilizer, biosolids-based organic mineral fertilizer, compost topdressing, natural areas). We measured leachate from these landscapes weekly for 1 year. All residential landscapes, including control yards that received no N fertilizer, leached >10x more nitrate than natural areas, and landscapes treated with synthetic fertilizer exhibited an >80x increase in nitrate leaching. Fertilizer treatments also appeared to alter the N leaching composition, with a greater proportion of total dissolved N leaching coming from nitrate in fertilized treatments (synthetic and organic) compared to natural, control, or compost-treated landscapes. These results show that landscape management and human actions are important drivers of nutrient leaching in residential landscapes. While all residential lawns leached more N than natural areas, less leaching was associated with certain management approaches. When implemented at larger scales, these approaches may reduce the likelihood of negative impacts of residential landscapes on regional water quality.

Application of wastewater effluent to agricultural lands can serve as a sustainable approach to meet irrigation and nutrient needs for crop production. While nitrogen and phosphorous loadings can be effectively managed, concerns have been raised regarding the fate of emerging contaminants, including per- and polyfluoroalkyl substances (PFAS), which are widely detected in wastewater effluent. The objective of this paper was to evaluate the ability of three unsaturated flow and transport models, Pesticide Root Zone Model 5 (PRZM5), LEACHM, and HYDRUS-1D, to predict the distribution of PFAS in the soil profile at the Pennsylvania State University Living Filter site, which has received daily wastewater effluent applications for several decades. The models were modified to include adsorption at the air-water interface (AWI), which has been shown to be an important factor governing PFAS transport and phase distribution in the vadose zone. Simulations showed that PRZM5 did not accurately reproduce the observed perfluorooctanesulfonic acid (PFOS) behavior, which was attributed to the "tipping bucket" approach used for water flow that results in the disappearance of AWI during water flow. In contrast, both LEACHM and HYDRUS-1D captured the observed retention of PFOS and perfluorooctanoic acid (PFOA) over a 50-year simulation period. Due to differences in the approach used to calculate the AWI area, LEACHM predicted greater accumulation of PFOS and PFOA at the AWI compared to HYDRUS-1D. These findings indicate that mathematical models that directly account for unsaturated water flow and adsorption at the AWI are able to provide reasonable predictions of long-term PFAS leaching resulting from land application of wastewater effluent.

Land application of biosolids to pastures confers multiple agronomic and environmental benefits, particularly in coarse-textured soils with low nutrient and organic matter levels. However, concerns over potential water quality have led to more stringent regulations that will limit beneficial reuse of biosolids in Florida. This 3-year field study evaluated the impacts of biosolids application strategies on N and P leaching losses, and soil P availability in an established bahiagrass (Paspalum notatum Flueggé) pasture. Treatments consisted of 2 P sources (biosolids and inorganic fertilizer) applied at 0, 20, 40, and 60 kg total P ha^-1. Inorganic fertilizer treatments received the same N loads as the corresponding biosolids treatments. Biosolids and inorganic fertilizer increased in situ soil P availability and pore-water P concentrations relative to the control. Pore-water P concentrations increased linearly with P rate with the greatest values generally associated with inorganic fertilizer. Relatively low leachate P concentrations (below the detection limit of 0.025 mg L^-1 in 596 out of 777 samples) observed in the current study indicates minimum P offsite movement risk regardless of the P management strategy. Annual P mass leached was not affected by treatments; however, inorganic fertilizer resulted in modest but significant greater annual NO₃-N mass leached than the other treatments. Lack of biosolids application rate effect on P and N leaching losses indicates that reduction in biosolids imposed by new state regulation will likely have no positive impact on water quality. Data demonstrated that, when properly managed, biosolids can be an environmentally sound fertilizer source for pastures.

Per- and polyfluoroalkyl substances (PFAS) in surface and ground waters supplying municipal drinking water are a growing concern. However, PFAS concentrations in water treatment residuals (WTRs)-a solid by-product of water treatment-have yet to be explored. In a first of its kind assessment, we examine PFAS occurrence in seven calcium (Ca)-, iron-, and aluminum-based drinking water treatment residuals (DWTRs) and one wastewater effluent treatment residual (WWETR) produced using aluminum chlorohydrate (ACH). Only perfluoroalkyl acids (PFAAs) were detected, with total PFAA concentrations in the seven DWTRs produced from naturally recharged water sources ranging from 0 to ∼3.3 μg kg^-1; no PFAS were detected in either of the Ca-DWTRs. The ACH-WWETR contained the highest number and concentration of PFAAs (34 μg kg^-1). Desorption of resident PFAAs from the WTRs was negligible for the carboxylates (PFCAs). Some desorption of the sulfonates (PFSAs) was detected, particularly for PFOS which had the highest concentration among all resident PFAAs. The ACH-WWETR was further evaluated for its potential to attenuate additional PFAAs (3500 μg mL^-1 total PFAAs) in a biosolid-derived porewater matrix. Sorption was highest for long-chain PFAAs and subsequent desorption of the adsorbed PFAAs ranged from 0% to no more than 26%, with the WWETR mass added strongly affecting both PFSA and PFCA sorption/desorption. These findings suggest that WTRs, if introduced into the environment, are unlikely to be a major source of PFAS. Also, the use of particular WTRs as amendments may provide a beneficial reduction in PFAS mobility.

Reusing treated wastewater for irrigation is a sustainable way to recycle nutrients and reduce freshwater use. However, wastewater irrigation inadvertently introduces per- and polyfluoroalkyl substances (PFAS) into agroecosystems, causing concerns regarding potential adverse effects to ecosystem, animal, and human health. Therefore, a better understanding of the pathways by which PFAS accumulate in forage crops is needed. A greenhouse study was conducted to (1) quantify the contribution of root uptake versus foliar sorption of PFAS in corn (Zea mays) and orchard grass (Dactylis glomerata), (2) assess effects of PFAS-impacted wastewater irrigation on plant health, and (3) determine the potential implications for bioaccumulation. The greenhouse study was composed of four treatments for each forage crop to isolate the relative contribution of two uptake pathways. Results suggested that foliar sorption was an unlikely contributor to PFAS concentrations observed in crop tissue. Root uptake was identified as the predominant uptake pathway. PFAS were detected more frequently in orchard grass samples compared to corn silage samples. Additionally, corn exhibited a lower uptake of long-chain PFAS compared to grass. Overall, no plant health effects on growth attributable to PFAS concentrations were observed. Forage data suggest cattle exposure to PFAS would be largely short-chain PFAS or long-chain "replacement" compounds (>50%). However, cattle may still be exposed to potentially harmful long-chain PFAS; levels in the forage crops exceeded the tolerable weekly intake set by the European Food Safety Authority. This study provides insights on PFAS entry into the food chain and potential implications for livestock and human health.

The evolution and spread of antibiotic resistance are problems with important consequences for bacterial disease treatment. Antibiotic use in animal production and the subsequent export of antibiotic resistance elements in animal manure to soil is a concern. Recent reports suggest that exposure of pathogenic bacteria to glyphosate increases antibiotic resistance. We review these reports and identify soil processes likely to affect the persistence of glyphosate, antibiotic resistance elements, and their interactions. The herbicide molecular target of glyphosate is not shared by antibiotics, indicating that target-site cross-resistance cannot account for increased antibiotic resistance. The mechanisms of bacterial resistance to glyphosate and antibiotics differ, and bacterial tolerance or resistance to glyphosate does not coincide with increased resistance to antibiotics. Glyphosate in the presence of antibiotics can increase the activity of efflux pumps, which confer tolerance to glyphosate, allowing for an increased frequency of mutation for antibiotic resistance. Such effects are not unique to glyphosate, as other herbicides and chemical pollutants can have the same effect, although glyphosate is used in much larger quantities on agricultural soils than most other chemicals. Most evidence indicates that glyphosate is not mutagenic in bacteria. Some studies suggest that glyphosate enhances genetic exchange of antibiotic-resistance elements through effects on membrane permeability. Glyphosate and antibiotics are often present together in manure-treated soil for at least part of the crop-growing season, and initial studies indicate that glyphosate may increase abundance of antibiotic resistance genes in soil, but longer term investigations under realistic field conditions are needed. Although there are demonstratable interactions among glyphosate, bacteria, and antibiotic resistance, there is limited evidence that normal use of glyphosate poses a substantial risk for increased occurrence of antibiotic-resistant, bacterial pathogens. Longer term field studies using environmentally relevant concentrations of glyphosate and antibiotics are needed.