Journal of environmental quality最新文献

Excessive loading of phosphorus (P) in coastal systems has been a growing concern for watershed managers due to the link with harmful algal blooms. In particular, legacy P creates a persistent challenge for eutrophication management in a range of aquatic systems, including wetlands, lakes, and estuaries, as a source of indirect, internal P loading. Following reductions in external P loads, internal sediment sources have been known to release bioavailable P back into the water column, undermining nutrient restoration goals. This study investigates the flux dynamics and longevity of sediment legacy P in three subtropical rivers—Amite, Tangipahoa, and Tickfaw—draining into the Lake Pontchartrain estuary. We employed a controlled laboratory incubation using intact and dredged sediment cores subjected to both aerobic and anaerobic treatments to quantify the flux of soluble reactive P over an 8-week period with regular surface water replacements. The soluble reactive phosphorus (SRP) flux under anaerobic water column conditions was three to five times higher than under aerobic conditions, with the most significant release occurring during the first 4 weeks. Following the fourth week, cores across all treatments observed a significant decrease in the rate of SRP released. Dredged cores showed consistently lower SRP flux across both aerobic and anaerobic treatments. These findings underscore the salient role of redox conditions and recent sediments in the mobilization of legacy P in river networks. Our work provides new evidence of the temporal limitation of internal P loading and the potential for strategic sediment management to complement external nutrient load reduction efforts to improve surface water quality.

Soil environmental capacity (SEC), a key indicator of the soil's ability to sequester pollutants and maintain ecosystem services, is vital for effective urban environmental management. However, traditional methods for evaluating SEC often overlook the complex spatial heterogeneity of environmental drivers. This study introduced an integrated approach combining eXtreme Gradient Boosting, SHapley Additive exPlanations, and geographically weighted regression (GWR) to compare the spatiotemporal dynamics and key drivers of SEC in Zhenhai and Tianjin, China, representing distinct landscape and socioeconomic contexts. Results revealed steep SEC gradients in Zhenhai, driven by industrial concentration, and a more uniform distribution in Tianjin, influenced by urbanization. From 1997 to 2021, Tianjin's SEC remained stable, whereas Zhenhai experienced a sharp decline after 2013. The analysis identified land use and cover change (LUCC) as key drivers in Zhenhai, whereas gross domestic product dominated in Tianjin. The GWR results revealed spatial heterogeneity in SEC drivers, with LUCC dominating Zhenhai's urban and industrial zones, while in Tianjin, economic fluctuations had contrasting impacts, reflecting regional differences in economic activities and pollutant dispersion. These findings highlighted the need for tailored soil management strategies to mitigate pollution risks in rapidly urbanizing areas.

The sustainable intensification of crop production provides more output with similar or fewer inputs, and therefore helps to produce food, feed, fiber, and fuel more efficiently. While short-stature maize (Zea mays L.) hybrids have been shown to be more climate resilient, with reductions in yield-scaled greenhouse gas production due to reduced crop damage during wind events, other aspects of the climate impact of short-stature maize remain to be quantified. Here we will discuss the use of the greenhouse gases, regulated emissions, and energy use in transportation life cycle assessment model and data inputs from 199 total site-years of grain yield data, 11 site-years of root data, and 10 site-years of stover nitrogen (N) data to determine the carbon (C) footprint of short-stature maize systems for grain production. Short-stature maize hybrids had comparable grain yields to tall comparators under standard management; however, leveraging benefits of the systems, such as in-season access, and higher plant populations improved the yield and efficiency of production. Root volume was increased by 39% for short-stature hybrids compared to tall hybrids. Across a range of agronomic system scenarios, that consider changes in plant density and improved in-season access for split-rate N application, and soil C dynamics, there is a range of greenhouse gas savings of 0.09–0.78 t CO₂e ha⁻¹ year⁻¹ for short-stature maize systems due to improvements in grain yield without increased inputs, reduction in stover N and subsequent N₂O emissions, and increased root dry matter incorporation into soil organic carbon.

Elovaara, S., Zhao, L., Asmala, E., Kaartokallio, H., & Thomas, D. N. (2025). Changes in riverine dissolved organic matter caused by gypsum-induced flocculation. Journal of Environmental Quality, 54, 369–381. https://doi.org/10.1002/jeq2.70001

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Efficient and sustainable nitrogen (N) management is critical for addressing the dual challenges of maximizing productivity and mitigating environmental impacts in short-cycle crops like lettuce (Lactuca sativa). This study evaluates the agronomic performance and nutrient dynamics of eight N fertilizer treatments, including mechanochemically synthesized urea-based cocrystals, conventional urea, and mechanochemically synthesized carbonate salts alongside accessible digital phenotyping methods for a greenhouse-grown romaine lettuce system. Plant growth, biomass production, chlorophyll content, and soil N residues were measured in conjunction with digital image-derived spectral indices from traditional photography. Engineered sulfate cocrystals (zinc sulfate urea and copper sulfate urea) performed comparable to or better than urea in promoting growth and N use efficiency, while engineered carbonates displayed moderate responses, likely due to slower N release. Traditional image-based indices such as normalized green-red difference index, hue angle, and green color distance metric, as well as more unique visual calculations, effectively captured plant nutritional status and correlated with chlorophyll levels. Principal component and cluster analyses further distinguished treatment performance based on growth and color metrics. These findings demonstrate the potential of combining novel N delivery systems with low-cost phenotyping technologies to transform sustainable nutrient management practices across diverse crop systems.

System fertilization enhances logistics and phosphorus (P) use efficiency, but its effects in high P-export systems, particularly regarding fertilization timing, placement, and distribution, remain unclear. This study evaluated P fertilization timing (90, 45, and 0 days before winter crop sowing [DBS]), placement (banded vs. broadcast), and spatial distribution (17 × 5 vs. 40 × 10 cm) in subtropical Oxisols with medium and high soil-test P. Over 4 years, we assessed crop yields, partial phosphorus balance (PPB), and Mehlich-1 available soil P (0–10 and 10–20 cm) under rotations of corn (Zea mays L.), soybean (Glycine max L.), and winter crops including black oat (Avena strigosa Schreb.), barley (Hordeum vulgare L.), vetch (Vicia sativa L.), and fodder radish (Raphanus sativus L.). Despite pronounced P stratification, yields and PPB were generally unaffected. In medium P soil, the 40 × 10 cm spacing increased P in the 10–20 cm layer to 61% of the critical value after 4 years. In high P soil, P application at winter sowing raised subsurface P to 4.5 mg dm⁻³. Soybean yield (5.2 Mg ha⁻¹) and PPB (73%) peaked with 90 DBS banded fertilization. Anticipating fertilization by 90 days with 17 × 5 cm spacing improved soybean yield by 20% and PPB by 10% due to better surface P distribution. The 0–10 cm layer remained P-rich and sufficient for grain yield. However, the benefits of 90 DBS were limited to two seasons. Long-term studies are needed to refine system fertilization strategies in high-output grain systems.

Excess of nitrogen (N) and phosphorus (P) increases the eutrophy level and can produce severe algal blooms in lakes and ponds. We introduce tycho-filtration based on self-settling algae aggregates, a biotechnology to extract excess of N and P from hypertrophic waters. This technical note has the following four scopes: (i) explaining the operating principle of tycho-reactors, (ii) drawing attention to parameters that may influence performance, (iii) identifying strategies for containing nuisance organisms in tycho-reactors, and (iv) discussing potential applications of this technology. A proof of concept 3 m² tycho-reactor with 880 liters per hour daily-peak flow-through rate yielded ≤120.4 g dry weight (DW) algae biomass m⁻² day⁻¹. This biomass consisted of 55% desmid Chlorophyceae and 44.8% diatoms vol:vol, carrying ≈4.16% N and ≈0.43% P per DW. Biological interferences requiring specific management include surface-attached filamentous algae, toxin-producing cyanobacteria, and the algae-eating bladder snail (Physella acuta). Advantages of tycho-filtration are predicted to come from photosynthesis being reliant on solar light, low cost of algae harvesting, potential for automation, and suitability for solar-based water flow. Potential applications of this technology include preventing severe algal blooms in small lakes, control of N in recirculated aquaculture, and detrophication of liquid effluents from aquafarms that threaten downstream ecosystems.

With the search for water security, the reuse of water in irrigation becomes interesting and inevitable. Given the complexity of soil–solute interactions, the use of simplified artificial solutions represents an innovative approach, as it facilitates understanding these interactions while posing no risk to human health or the environment. However, the more complex and inferior the quality of the water, the greater the environmental contamination risk. The objective of this study was to investigate ion retention in three tropical soils (Oxisol, Inceptisol, and Entisol Quartzipsamment) by applying treated domestic wastewater (TWW) and artificial wastewater, both with the same concentrations of Na⁺, K⁺, Ca²⁺, and Mg²⁺ as the TWW. Physical, chemical, and mineralogical properties of the soil were determined. Multivariate analysis was performed to elucidate the relationships between the solutes’ transport parameters, the soils’ mineralogy and texture, and the variation in their chemical characteristics resulting from wastewater application. Oxisol and Entisol Quartzipsamment contributed to principal component 1. The second principal component had a negative contribution from Inceptisol. Oxisol and Entisol Quartzipsamment showed the longest delays of ion transport relative to the wetting front. Inceptisol had the lowest retardation factors and the lowest affinity for ions. For the TWW on Oxisol, Na⁺ was the first ion to reach a relative concentration equal to 1, at an average pore volume of 4.3; however, the last pore volume collected for Ca²⁺ was 12.3, with a relative concentration of 0.6, showing that sodium in TWW is a point of attention, as observed by the low affinity with soils.

In this study, changes in P runoff losses from three field-scale small watersheds in the Northern Great Plains region (Manitoba, Canada) under organic management were evaluated over a 7-year period (2017–2023). A perennial forage crop was grown through this time period, either with biennial addition of a slow-release fertilizer to maintain soil fertility (struvite, 4 site-years) or without P amendment (drawdown, 8 site-years). Annually measured soil P (Olsen P) strongly correlated with mass balance of P added as struvite or removed by crops and surface runoff. As a result, P limitation of forage yield was observed in the later years of the drawdown treatment. P loads and flow-weighted mean concentrations (FWMCs) measured in snowmelt runoff after struvite application were compared to predicted values using published regional models developed with 82 site-years of data from field-scale small watersheds, with Olsen P, water yield, and percent surface cover as predictors. To evaluate response to struvite over a wider range of conditions, P runoff was measured in two additional watersheds under conventional annual grain production following struvite application (2 site-years). Higher risk of P loss was observed with higher Olsen P. However, following struvite applications, the risk of P loss to snowmelt was consistently lower than predicted (between −0.13 and −0.85 mg L⁻¹ for FWMC of total dissolved P) suggesting that the solubility of struvite in runoff water may be lower than for other forms of soil P also extractable as Olsen P.

Effective management of surface water quality requires a thorough knowledge of the characteristics and contributions of various pollution sources. While stable isotope methods are highly effective for nitrate source tracking, their high cost and operational complexity constrain their routine use in watershed management. This study examined and contrasted the dual stable isotopes (δ¹⁵N-NO₃⁻, δ¹⁸O-NO₃⁻, and the MixSIAR [Bayesian mixing models in R] model) with fluorescence analysis (EEM-PARAFAC [fluorescence excitation–emission matrices coupled with parallel factor analysis]) to trace the origins of nitrate and dissolved organic matter in the Lujiang River, a coastal agriculture-dominated river in southeastern China. Additionally, the feasibility of EEM-PARAFAC as a low-cost complementary tool for nitrate source tracking was assessed. The MixSIAR model identified soil nitrogen (41.0%–49.7%) and fertilizers (29.5%–37.9%) as dominant nitrate sources, pointing to significant nonpoint source pollution. With increasing urbanization, point source pollution from manure and sewage increased from upstream (11.5%) to midstream (13.1%) and downstream (15.3%). EEM-PARAFAC analysis supported these findings, with humic-like components (C1 + C2: 59.31%, 56.85%, and 46.98% in upstream, midstream, and downstream, respectively) showing a strong correlation (r = 0.97) with soil nitrogen contributions identified by MixSIAR. Protein-like components (C5, r = 0.93; C6, r = 0.97) were associated with fertilizers and sewage, respectively, consistent with their increasing downstream contributions, validating EEM-PARAFAC's capacity for cost-effective source discrimination. This study demonstrates that integrating the two methods enhances the understanding of pollutant source dynamics in complex river systems, offering valuable insights for improving water quality and watershed management.