Journal of environmental quality最新文献

Agricultural researchers are increasingly encouraged to engage with stakeholders to improve the usefulness of their projects, but iterative research on the design and assessment of stakeholder engagement is scarce. The USDA Long-Term Agroecosystem Research (LTAR) Network recognizes the importance of effective engagement in increasing the utility of information and technologies for future agriculture. Diverse stakeholders and researchers at the Kellogg Biological Station (KBS) LTAR site co-designed the KBS LTAR Aspirational Cropping System Experiment, a process that provides a testing ground and interdisciplinary collaborations to develop theory-driven assessment protocols for continuous stakeholder engagement. Informed by prior work, we designed an assessment protocol that aims to measure participant preferences, experiences, and perceived benefits at various stages of this long-term project. Two online surveys were conducted in 2021 and 2022 among participants of LTAR engagement events at KBS, using a pre-post design, resulting in 125 total responses. Survey respondents had positive perceptions of the collaboratively designed research experiment. They had a strong expectation that the research would generate conservation and environmental advances while also informing policy and programs. Respondents also indicated a desire to network with other stakeholders. The research team noted the significant role of a long-term stakeholder engagement specialist in inviting participants from diverse backgrounds and creating an open and engaging experience. Overall, results highlight an interdisciplinary path of intentional and iterative engagement and evaluation to build a program that is adaptive and responsive to stakeholder needs.

Soil ecophysiology is adversely affected by various environmental hazards, particularly in mining regions. While there has been substantial research on the effects of coal, mica, copper (Cu), and manganese (Mn) mining on soil quality, the impact of bauxite mining operations on nearby soils has largely been overlooked in the literature. Therefore, this study aims to investigate how microbial activity and dynamics are influenced by soil stressors, such as acidity and heavy metals, in areas adjacent to active bauxite mines. Soil samples were collected from three adjacent locations of an active bauxite mine area at distances of <100 m (S1), 100-500 m (S2), and >500 m (S3). The samples contained chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), zinc (Zn), manganese (Mn), and cadmium (Cd), as well as elevated acidity and aluminum (Al). These conditions adversely affected the soil microbial indicators, including fluorescein diacetate (FDA), microbial biomass carbon (MBC), and enzyme activity. The highest concentrations of labile metals (i.e., water-soluble and exchangeable) were found in soil mixed with mining waste (S1), whereas acidity and Al were highest in sparsely vegetated soil (S3). Total acidity, total potential acidity, pH-dependent acidity, and Al were significantly positively correlated. Moreover, the significant positive correlation among organic carbon (OC), acidity, Al, and microbial properties (FDA, MBC, and microbial enzymes) suggests a potential effect of OC in mitigating acidity in S3. The ratios of microbial properties with OC depicted a significant negative correlation with acidity and Al fraction, denoting that acidity and Al posed a deleterious effect on soil microbial health. The similarity percentage analysis identified acid phosphatase as the key enzyme accounting for ∼78% of the observed differences in enzyme composition across the sites. Visual MINTEQ modeling revealed that the sites were saturated with different Al-bearing minerals. Pollution load index (PI) and the geo-accumulation index (I_geo) values identified the region as heavily contaminated (PI > 1). Finally, the health risk analysis revealed that Ni posed a potential carcinogenic risk for both adults and children.

Evaluating how weather, farm management, and soil conditions impact phosphorus (P) loss from agricultural sites is essential for improving our waterways in agricultural watersheds. In this study, rainfall characteristics, manure application timing, tillage, surface condition, and soil test phosphorus (STP) were analyzed to determine their effects on total phosphorus (TP) and dissolved phosphorus (DP) loss using 125 site-years of runoff data collected by the University of Wisconsin Discovery Farms and Discovery Farms Minnesota. Three linear mixed models (LMMs) were then used to evaluate the influence of those factors on TP and DP losses: (1) a model that included all runoff events, (2) manured sites only, and (3) precipitation events only. Results show that the timing of manure application relative to the timing of a runoff event only had a marginal association with P loads and concentrations, although the majority of the runoff events were collected after 10 days of manure application. Tillage was as influential factor, with greater DP loads and concentrations associated with no-till, especially during frozen conditions. Fields in this study had high STP values, but the model results only showed positive associations between DP load and DP flow-weighted mean concentration (FWMC) loss at the 0- to 15-cm depth. The precipitation event LMM (which included precipitation characteristics) was the model that resulted in the largest R² value. While the predictive capacity of the LMMs was low, they did illuminate the relative importance of management and environmental variables on P loss, and can be used to guide future research on P loss in this region.

Atmospheric nitrous oxide (N₂O) is a potent greenhouse gas, with long atmospheric residence time and a global warming potential 273 times higher than CO₂. N₂O emissions are mainly produced from soils and are influenced by biotic and abiotic factors that can be substantially altered by anthropogenic activities, such as land uses, especially when unmanaged natural ecosystems are replaced by croplands or other uses. In this study, we evaluated the spatial variability of N₂O emissions from croplands (maize, soybean, wheat, and sugar cane crops), paired with the natural grasslands or forests that they replaced across a wide environmental gradient in Argentina, and identified the key drivers governing the spatial variability of N₂O emissions using structural equation modeling. We conducted on-farm field measurements over 2 years at nine different sites, including a wide environmental gradient (mean rainfall from 679 to 1090 mm year^-1 and mean temperatures from 13.8°C to 21.3°C), with diverse plant species life forms, and ecosystems, from the Semiarid Chaco forests in the Northwest of Argentina to the Pampas grasslands in the Southeast. On average, agricultural systems emitted more than twice N₂O (+120%), had higher soil water content (+9%), higher soil temperatures (+3%), higher soil nitrate content (+19%) but lower ammonium (-33%) than natural ecosystems. We found that land use was the main driver of N₂O emissions by directly affecting soil NO₃ ^- contents in both natural ecosystems and croplands. Urgent management practices aimed at reducing N₂O emissions from croplands are needed to mitigate their contributions to global climate change.

Eastern North Carolina has been subjected to widespread water quality degradation for decades, notably throughout the Cape Fear River Watershed, owing largely to the magnitude of concentrated animal feeding operations (CAFOs) in the region. Long-term nutrient monitoring data from numerous locations throughout southeastern North Carolina have shown significantly elevated organic nitrogen (Org-N) concentrations starting around the year 2000-a concerning development, as labile Org-N can stimulate algal blooms and subsequent bacterial production, thus enhancing eutrophication in freshwater systems. By measuring the stable isotope signatures (δ¹³C, δ¹⁵N) of particulate organic matter sampled from a range of southeastern North Carolina waters, the predominant sources to the observed Org-N loadings were elucidated. Isotope data from across the Cape Fear River watershed indicated a large gradient of livestock waste-N contributions, with hog waste-N contributions consistently higher in the Northeast Cape Fear River watershed and with fertilizer-N contributions higher in the Black River watershed-findings that are consistent with each sub-basin's land usage. %N sediment content was positively correlated with hog waste-N contributions in the Black River watershed, indicating that sediments in CAFO-dense regions are reservoirs for agricultural nutrient pollution. Hog waste-N source contributions and %N sample contents for Black River sediments were strongly correlated with regional swine and poultry CAFO densities, establishing a strong connection between industrial animal production and stream sediment nutrient loads. Collectively, these findings suggest a major role of livestock waste, as well as human sewage, in driving the long-term Org-N increase in eastern North Carolina water bodies.

Ephemeral streams are important pollutant conduits, but the mechanisms that control nutrient transport to these systems remain unclear. In the US Virgin Islands (USVI), where most streams flow ephemerally, a lack of continuous hydrologic and water quality data limits our understanding of streamflow behavior and its influence on water quality. We therefore assessed the impact of soil moisture and hydrometeorological conditions on nitrogen (N) concentrations within an ephemeral stream on St. Croix, USVI. Stream N concentrations were usually highest during initial flow events, after prolonged dryness, and declined thereafter. Nitrogen increased with shallow antecedent soil moisture and rainfall intensity and decreased with deep soil moisture and baseflow emergence, indicating it was predominantly exported to the stream via surface runoff, as opposed to subsurface leaching. Our results are the first of their kind for the USVI and could be used to improve water quality of freshwater and marine systems.

Nutrient losses via subsurface tile cause environmental degradation of aquatic ecosystems. Various management practices are primarily aimed at reduction of nitrate leaching in tile discharge; however, studies on leaching of other nutrients are limited. A replicated plot experiment was initiated in 2016 as part of the Long-Term Agroecosystem Research (LTAR) network Croplands Common Experiment to quantify the effectiveness of management practices on leaching of NO₃-N, total P, K, and S from drained soils. Corn (Zea mays L.) and soybean (Glycine max L. Merr.) were grown under five different treatments: (1) BP: basic practice with fall chisel plow; (2) NT: no-till crop production; (3) RC: no-till with a winter rye (Secale cereale L.) cover crop; (4) DW: no-till with woodchip denitrification walls parallel to both sides of the tile; and (5) ZN: zero N; no-till without N fertilization. Compared to BP, both RC and DW treatments reduced NO₃-N load by 63% and 47%, respectively; 15.5, 5.8, and 8.2 kg N ha^-1 year^-1, while omitting N fertilization did not impact N loads (12 kg N ha^-1 year^-1). The DW resulted in greater K loss compared to BP, presumably due to decomposing woodchips. No-till practices increased drainage flow and K and P loads compared to conventionally tilled BP plots but had no impact on other nutrients. The BP produced the highest corn yield, whereas soybean yields were not affected by treatments. These findings indicate that while some conservation practices are effective in reducing nutrient leaching, others are likely to increase their loss and reduce crop yields.

Although ecosystem management and restoration are known to enhance carbon storage, limited knowledge of ecosystem-specific soil organic carbon (SOC) stocks and processes hinders the development of climate-ready, biodiversity-focused policies. Baseline SOC stocks data for specific ecosystems is essential. This paper aims to: (i) examine SOC stock variability across major grassy ecosystems in Brazil and (ii) discuss data limitations and applications. We compiled the Grassland Synthesis Working Group dataset, which comprehensively aggregates SOC stocks data from published studies on main Brazil's grassy ecosystems. Our dataset results from systematic literature review and regional soil sampling datasets. The dataset provides spatially explicit SOC stocks, physical soil properties, and ancillary information from 182 studies (1996-2021) across 803 sites, spanning 35° latitude and 28° longitude. The dataset, structured in relational tables, reports soil C stocks and ancillary soil parameters at depths up to 100 cm. SOC stocks vary by grassy ecosystem types and sampling depth, with subtropical grasslands (Campos Gerais, South Brazilian highland grasslands, and Pampa) showing the highest SOC stocks across all depth layers (SOC 0-30 cm: 64.5-162.8 Mg C ha^-1; SOC 0-100 cm: 137.6-224.7 Mg C ha^-1). The tropical Cerrado and Amazon grassy ecosystems exhibit high SOC stocks, particularly in subsurface layers (SOC 0-30 cm: 53.6 and 38.3 Mg C ha^-1; SOC 0-100 cm: 109.8 and 121.4 Mg C ha^-1, respectively). Our data analysis shows high carbon stocks in natural/seminatural ecosystems, but some ecosystems are undersampled. The dataset on SOC stocks in grassy ecosystems could greatly aid Brazil's national greenhouse gas inventory.

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.

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.