Journal of environmental quality最新文献

The phosphorus (P) availability's role in carbon (C) and nitrogen (N) accumulation in long-term systems remains unclear. This study evaluated the P fertilization's influence on C and N storage, C:N ratio, humic matter, and the C:clay ratio in two long-term corn (Zea mays L.)/soybean [Glycine max (L.) Merr.] rotation trials under conservation tillage in North Carolina. Soil samples were collected at 0–5, 5–10, 10–20, and 20–30 cm. A linear-plateau model evaluated the effect of soil test phosphorus (STP), from long-term fertilization, on C and N stocks at 0–10, 0–20, and 0–30 cm. Both sites exhibited depth-based STP gradients, although P rates significantly affected C stocks only in the 0–10 cm layer at Tidewater. P availability influenced C stocks at both sites, with greater P content and a higher critical soil test phosphorus value (CSTV) in Tidewater. CSTVs derived from C and N stocks were strongly correlated with those based on relative crop yield (R² = 0.99). On average, the sandy soil at Tidewater accumulated more C than the clayey soil at Piedmont, reflecting differences in C stabilization. Maintaining soil test phosphorus near the CSTV increased C stocks by 2.1–2.7 Mg ha⁻¹ and N stocks by 0.2–0.3 Mg ha⁻¹ across the evaluated depths, contributing to improved soil fertility and agroecosystem resilience. Piedmont soils, despite lower total C stocks, showed greater C storage potential due to higher clay content, reinforcing the need for site-specific P management adapted to soil texture and C stabilization capacity.

Schantz, M. C., Hardegree, S. P., Abatzoglou, J. T., Fullhart, A., Adhikari, K., Harmel, R. D., Thorp, K. R., Leyton, J. O., & Smith, D. R. (2026). Precipitation forecasting utility for proactive agroecosystem management: A case study from the Texas Gulf LTAR site. Journal of Environmental Quality, 55, e70132. https://doi.org/10.1002/jeq2.70132

The last name of the fifth author listed on this paper, Kabindra Adhikari, was misspelled as Kabindra Adhikhari. The name is now corrected in the author byline, the Author Contributions section, and the How to Cite this article section. In addition, the spelling of the last name is also corrected in the Schantz et al. (in press) reference in the reference list.

We apologize for this error.

High total phosphorus (TP) concentrations in freshwater such as streams, rivers, and lakes remain a global issue, causing eutrophication and poor ecological conditions. We extracted annual flow-weighted TP concentration data (N = 3144) from 207 monitored Danish headwater streams (catchment area < 50 km²) during the period 1990–2019 as the basis for developing a machine learning (ML) model for diffuse phosphorus in streams, using 22 potential predictor variables. We tested 70 different algorithms, applying an AI platform and a random split strategy with a holdout dataset (20%), a validation dataset (16%), and four training datasets (4 × 16%) in a fivefold cross-validation procedure across a total of 207 stream stations. The ML algorithm “eXtreme Gradient Boosted trees regressor: XGBoost” was identified as the best-performing model, based on 13 predictor variables, with a relatively high explanatory power for the training dataset (R² = 0.68), the cross-validation dataset (R² = 0.71), and the holdout dataset (R² = 0.66). The most important catchment characteristics of the 13 predictor variables were paved area, tile drained area, clay content in subsoil, farmed area, and TP loss from bank erosion. An external test of model transferability on a dataset, using an additional 142 stream stations (N = 1261), revealed a somewhat lower predictive power of the final model (R² = 0.41). The final model was applied to simulate annual diffuse flow-weighted TP concentrations for 3200 unique headwater catchments (ca. 15 km²) and this analysis now supports the calculation of annual TP loadings to surface waters from otherwise ungauged coast-near areas in Denmark.

Per- and polyfluoroalkyl substances (PFAS) are persistent organic pollutants that accumulate across aquatic compartments, which include sediments, pore water, surface water (including microlayers), suspended particulate matter (SPM), fish, and other biota, causing long-term ecological impacts. This review analyzes the global distribution of PFAS in aquatic sediments, partitioning behavior across aquatic compartments, and ecological consequences of PFAS on sediment-dwelling organisms. PFAS in sediments are widespread globally, with the highest mean concentration (274.1 ng/g) found in the African continent, in addition to localized hotspots showing increased average levels in other continents. SPM consistently retains higher PFAS levels than sediments, while porewater concentrations exceed those of surface water (SPM > sediment, porewater > surface water), revealing overlooked exposure pathways. Sediment-bound PFAS exposes benthic organisms through dermal contact, ingestion, and trophic transfer, with bioaccumulation influenced by organism traits, sediment properties, and environmental factors. Although ecological risk quotient (RQ) values are generally low (RQ < 0.1), localized hotspots and species-specific sensitivities highlight the need for site-specific monitoring. Regulatory frameworks in the EU and United States remain focused on drinking and surface waters, lacking sediment-specific standards and leaving a critical policy gap. Thus, this review suggests sediments as an important yet underexplored reservoir of PFAS, indicating the importance of incorporating sediment compartments into monitoring, ecological risk assessment, and regulatory frameworks.

In Germany during several decades, emissions and thus the chemical climate affecting forests have changed significantly. The effects of these changes on the element balance of forests can be documented only by long-term observations, as has been done at the Höglwald site (Southern Bavaria) since 1985. Since then, structural changes in agriculture have led to a reduction in emissions of reduced nitrogen (NH₃). There was also a slight decrease in emissions of oxidized nitrogen (NO_x). Air pollution control measures, especially in the 1980s, led to a particularly drastic reduction of sulfur emissions (SO₂). Consequently, inputs to the ecosystem decreased by almost 95% between 1985 and 2020. Dry deposition nowadays plays practically no role for this element. High nitrogen inputs, dominated by reduced nitrogen, have led to a high proton production through N transformations. This has gradually reduced the buffering capacity of the topsoil. Comparing measured fluxes shows that with decreasing sulfur inputs, the sulfur stored in the topsoil from times of high deposition was remobilized. At the Höglwald, this process occurred rather clearly over a period of about 28 years and has resulted in only about 11% of the initial amount of sulfur being still present in the topsoil (humus layer + mineral soil down to 40 cm) in 2020. Forestry should take the changed chemical conditions into account in its nutrient management.

Agricultural runoff accounts for >40% of Chesapeake Bay's nonpoint source nitrogen (N) pollution, representing a complex problem requiring systems-level management approaches. Traditional nitrogen management strategies, focused primarily on field-level best management practices, have proven insufficient to achieve watershed restoration goals, underscoring the need for systems-level management approaches that account for interactions across the entire food production chain. In this study, we investigate the effects of simulated future agricultural changes and management scenarios on agricultural N loss in the Chesapeake Bay Watershed using a systems approach production chain analysis that tracks nitrogen flows through seven distinct stages of food production, processing, and consumption chains. We developed scenarios including future agricultural intensification, efficiency improvement management strategies, and combined scenarios to evaluate system-wide responses. Our results show that a combination of interconnected factors is the most influential in controlling total nitrogen loss, including expected factors like the production amounts of crops and animals and fertilizer application rates, as well as several less widely discussed factors, including live animal weight gained and feed conversion ratios. Although live animal weight gain and feed conversion ratio were previously identified as sensitive variables in earlier applications of the nitrogen flow model, our study advances this work by quantifying their relative importance to total nitrogen loss. In addition, the present analysis extends these insights to future climate-impacted scenarios by incorporating climate-driven changes in crop yields and projected growth in animal production. This combined approach clarifies not only which factors matter most but also how their influence evolves under changing environmental and production conditions, thereby identifying the most consequential leverage points for future nitrogen management. These findings demonstrate that systems-level perspectives across interconnected food production chains can provide viable information for identifying pathways to meet watershed quality objectives while accommodating projected agricultural intensification under changing climate conditions.

Vanadium (V) is a potentially toxic metal widely distributed in the environment. This study investigates temperature effects on V adsorption and speciation in biochar (BC) and BC–metal oxide composites under conditions relevant to contaminated soils in temperate climates. While BC and metal oxide nanoparticles can individually immobilize V, limited information exists on temperature effects. This study investigates V adsorption and surface characteristics of BC alone and BC combined with iron (Fe), aluminum (Al), and titanium (Ti) oxide nanoparticles (BC: oxides at 5:1 ratio) at warm (22°C) and cold (4°C) temperatures. V adsorption was conducted at pH 7.5 using concentrations from 0 to 40 mg L⁻¹. Visual MINTEQ modeling software was used to predict dissolved V species at experimental conditions. Surface characteristics were examined using scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) and Fourier transform infrared spectroscopy. Adsorption data were fitted to the Freundlich (r² ∼0.99) and Langmuir (r² = 0.66–0.96) isotherms. Maximum adsorption capacity followed the order: BCAl-cold = BCAl-warm > BCTi-cold > BCTi-warm = BC-cold = BC-warm > BCFe-warm = BCFe-cold. Predicted orthovanadate (%) was higher at warm temperatures. H₂VO₄⁻ was the dominant species at pH 7.5 under both temperatures. Microaggregates were observed in BCAl and BCTi, indicating greater surface area than BC or BCFe. SEM-EDS showed V and Al enrichment on BCAl surfaces suggesting the inner-sphere complexes between Al–oxygen (O) and H₂VO₄⁻. These results offer mechanistic insight into V adsorption on BC–nano-oxide composites under varying climatic conditions and support their potential use in remediating V-contaminated soils.

Urbanization generates significant amounts of sewage sludge (SS), with relatively high concentrations of plant nutrients such as phosphorus (P). When biochemically stabilized by composting, SS (composted sewage sludge [CSW]) can serve as a sustainable P source in agriculture, supporting a circular economy and reducing agriculture's dependence on finite phosphate rock. The objective of this study was to assess the ability of CSW to supply P to plants grown on calcareous and noncalcareous soils of contrasting properties. Compost quality was assessed to support the scaling up of this study for agronomic application. Durum wheat (Triticum durum L.) was grown under controlled conditions, and three treatments were applied to the soils: (1) control without P (CON), (2) diammonium phosphate (DAP)—a common synthetic P fertilizer, and (3) CSW, the last two to supply 50 mg kg⁻¹ of P. The P content was 46% higher in CSW than before composting (24.0 vs. 16.4 g kg⁻¹). In the pot experiments, total soil P concentrations increased by 11% with DAP and CSW relative to CON. The highest P internal utilization efficiency was obtained with CON and CSW in the Entisol and CON in the Vertisol, while wheat grain yields were highest with DAP and CSW across soils. CSW increased harvest index and one-grain weight in the calcareous soil relative to CON. Moreover, CSW and DAP led to similar P uptake in wheat, significantly higher than CON. Our results highlight the potential of CSW as an effective P source for wheat in soils of southern Europe and others with similar properties.

Microplastics derived from agricultural plastic films accumulate in soils, potentially impacting ecosystem functions such as soil organic carbon (SOC) storage. Microbial degradation of biodegradable plastics, which are intentionally tilled into soil, may accelerate or inhibit the mineralization of native SOC, known as priming effects. Moreover, the interaction between microplastics and nitrogen (N) on SOC dynamics remains poorly understood, despite their concurrent presence in agroecosystems. We used a 193-day incubation experiment to investigate the degradation and priming effects of three biodegradable microplastics (polybutylene succinate [PBS], polylactic acid [PLA], and a PLA-polyhydroxyalkanoate blend [PLA/PHA]) compared to a conventional microplastic (low-density polyethylene [LDPE]) in agricultural soil under low and high N conditions. Isotope (¹³C) tracing allowed us to determine the cumulative loss of plastic- versus SOC-derived C as CO₂-C. Biodegradable microplastics varied in biodegradation rates and priming effects, with PLA/PHA losing the most plastic-C (17.88%) and inducing the greatest positive priming effects (371 µg C g dry soil⁻¹). In contrast, PLA, PBS, and LDPE showed <1% plastic-C loss and weaker priming effects ranging from positive to negative (73.1, 8.81, and −45.4 µg C g dry soil⁻¹, respectively). Although N addition decreased total C loss from both native SOC and microplastics, it did not alter priming effects. Priming effects were positively associated with dissolved organic and microbial biomass C, enzyme activities, and pH. We conclude that biodegradable microplastics may threaten native SOC pools, and higher N availability may promote persistence of biodegradable plastics in soils.

In rural areas, unpaved roads can drive water quality degradation via sediment inputs. Excess sediment loss from poorly maintained unpaved roads to adjacent waterways blocks sunlight, decreasing primary productivity and increasing nutrient concentrations. This is particularly relevant to Arkansas, where 85% of county roads are unpaved; however, few studies have explored the impacts of unpaved roads in rural watersheds dominated by pasture. We sampled Brush Creek (Arkansas) to understand local (i.e., road crossing type) and watershed-scale (e.g., land cover/use) controls on sediment loss. We collected monthly baseflow and four opportunistic storm flow samples for total suspended solids (TSS) upstream and downstream at bridge, culvert, and direct stream crossings. Mean TSS yields downstream versus upstream of road crossings were comparable, especially at bridge and culvert sites, indicating these road crossings may not be critical TSS sources. At the watershed scale, TSS load showed increasing trends as both total length of unpaved roads and area of pastureland in a subwatershed increased (linear mixed effects; β = 0.03, R² = 0.41, p > 0.1; β = 0.67, R² = 0.42, p = 0.07, respectively). Moreover, TSS yields were higher during stormflow than baseflow (26.87 ± 6.82 vs. 0.38 ± 0.04 kg km⁻² day⁻¹; unpaired t-test, p < 0.01). Finally, seasonality influenced local and watershed patterns of TSS loss via variation in transport controls, including wet season conditions, discharge rates, and overland flow. Our findings indicate watershed-scale characteristics are key contributors to sediment loss in rural watersheds. Targeted best management practice implementation should focus on unpaved roads and pasturelands during key transport periods to effectively protect downstream water quality.