Journal of environmental quality最新文献

Iowa Learning Farms, based at Iowa State University since 2004, is a nationally recognized conservation outreach program that has successfully engaged with farmers and landowners to deliver information and provide tools and guidance encouraging the implementation of agricultural practices that enhance water quality, improve soil health and productivity, and contribute to building a Culture of Conservation in Iowa and beyond. Iowa Learning Farms programs all focus directly on reaching and engaging with farmers. The program's success comes from the processes employed to create, test, and deliver programs that serve demographic groups including traditional row crop, new or next-generation, female, nontraditional crop, and livestock farmers, as well as tenants, landowners, and conservation professionals. Our programs include field days, webinars, Conservation Station trailers, rapid needs assessment and response workshops, Leadership Circle listening sessions, a youth education program, infographic-style factsheets, and a Whole Farm Conservation Best Practices Manual, as well as a newsletter, blog, and social media presence. Our programs foster a collaborative relationship with farmer partners, agencies, the university, researchers, and the public. The development, feedback, and iterative process of creating and refining programmatic elements will be highlighted.

We investigated the potential toxic effects of iron oxide magnetic nanoparticles (IOMNPs) of varied size, synthesized through biological and chemical methods on freshwater and marine microalgae and bacterial species. The study provides insights into pollution and ecological impacts of NPs. IOMNPs of two sizes, 20-50 nm (quasi-spherical) synthesized using a cell-free fungal extract (biogenic method), and 104 nm (spherical) obtained from a commercial source (chemical method), were tested for aggregation, bioavailability, and toxicity at multiple concentrations (12.5, 25, 50, 100, and 125 µg mL^-1). Microalgal growth media (Bold's basal media and sea salt media [SSM]) was used for aggregation analysis of IOMNPs using dynamic light scattering (DLS) technique. DLS analysis showed similar aggregation patterns for both type of IOMNPs, with relatively larger aggregate formation in SSM. Toxicity assessments showed that biogenic IOMNPs of smaller size 20-50 nm were non-toxic, while commercial IOMNPs of large size (104 nm) significantly reduced bacterial cell density and microalgal lipid and carotenoid content at higher concentrations. Further, transmission electron microscopy and X-ray fluorescence analysis confirmed IOMNP uptake by microalgae. TEM images showed more pronounced structural damage caused by the uptake of commercial IOMNPs. Our findings provide crucial insights into the differential impacts of IOMNPs based on their size and synthesis methods on key aquatic microorganisms and their potential to mitigate issues related to NP pollution.

In the highlands of Ethiopia, integrated community watershed management has drawn a lot of interest as a solution to low production and soil degradation. However, the documentation of its role in managing soil fertility and health under diverse landscape perspectives remains inadequate. The main objective of this study was to link the effects of landscape positions and soil management practices (conservation agriculture (CA) and non-CA) on selected soil properties. Disturbed and undisturbed soil samples were collected at a depth of 0-20 cm from 192 locations (16 different watersheds) to analyze texture, bulk density (ρd), pH, soil organic carbon (SOC), total nitrogen (TN), and available phosphorus (Av.P). The study used analysis of variance (ANOVA), Pearson correlation, and principal component analysis to examine the relationship between factors, identify patterns, and understand data variability. The findings indicated that the landscape position significantly affects the values of ρd, sand and clay, SOC, Av.P, and TN at p < 0.05. The sand, clay, ρd, SOC, Av.P, and TN showed statistically significant variations between CA and non-CA. The interaction effects of landscape positions and watershed management status (well and poor) were highly significant for the selected soil properties except for the silt and pH. The results also demonstrated a substantial correlation between the observed soil properties. Meanwhile, the principal components 1-3 collectively described 64.45% of the total variability. Therefore, it is possible to infer that successful watershed management intervention improves topsoil properties, which urges the maintenance and development of soil and water conservation, CA, and vermicomposting practices.

Excessive phosphorus (P) concentrations can lead to conditions that limit the amenity of freshwater resources. This problem is particularly acute in agricultural catchments, where P fertilizer and manure amendments have been used to increase soil fertility and productivity. In these catchments, P indices are often used to help target critical source areas in order to reduce P exports. However, the overall impact of agricultural mitigation efforts on receiving waters has not always been consistent with declines in total P exports from catchments. In this paper we propose a model of dissolved P mobilization (i.e., entrainment) in surface runoff that accounts for this outcome and examine modifications to P indices that better accommodate dissolved P mobilization. We suggest that dissolved P mobilization commences near the soil surface and has two phases. When water is first applied, labile P is mostly mobilized by dissolution and advection. Subsequently, as the supply of readily accessible P is exhausted, diffusion and hydrodynamic dispersion mobilize P from other sources at a near constant rate for the remainder of the event. As most P exports occur in larger (i.e., longer) events, the second phase appears responsible for most dissolved P exports. Such a model of dissolved P mobilization is consistent with runoff monitoring data under natural and simulated rainfall, suggesting that on low (shallow) slopes where the interaction between surface soil and water may be prolonged, dissolved P concentrations are likely to be higher. Dissolved P mobilization from low-slope areas is not well represented in P indices at present. We suggest that there needs to be a more complex, mechanistic structure to P indices that involves additional compartmentalization. Further, we suggest that this can be achieved without losing the simplicity of P indices or flexibility to integrate research data and experiential knowledge into tools that are relevant to specific regions.

Dairy farmers are interested in reducing the carbon footprint of milk. Reducing methane (CH₄) emissions is a key part of this goal, and manure is a significant CH₄ source. Technologies like anaerobic digesters for biogas production are effective; however, adoption rates are slowed by upfront costs and infrastructure needs. Achieving near-term emission reductions needs low-cost alternatives that can be quickly and widely adopted. Previous studies have shown that "acidification" of manure by adding sulfuric acid (H₂SO₄) suppressed CH₄ emissions; however, widespread adoption may be hindered by the challenge of handling acid on farms. This laboratory study was performed for 157 days at 24°C, and compared the efficacy of a sulfate-based non-acidic fertilizer (CaSO₄), and two rates of acidification, one at pH > 7 and one at pH < 7, for a sulfate-based acid (H₂SO₄) and a sulfate-free acid (H₃PO₄). Methane suppression by CaSO₄ at multiple rates was also analyzed. Two mechanisms of suppression were observed: acidification had a demonstrable early effect, lowering cumulative CH₄ emission within 40 days by up to 65% for H₂SO₄ and 54% for H₃PO₄, while sulfate-containing compounds showed increasing suppression after 50 days. Final cumulative CH₄ suppression was up to 63% for CaSO₄ and 91% for H₂SO₄, while H₃PO₄ was least effective. These results suggest H₂SO₄ is highly effective due to the combination of acidity and sulfate. Adding sulfate alone (CaSO₄) was more effective than adding acid alone (H₃PO₄). Hence, sulfate-based additives-like gypsum-may hold promise as an alternative near-term solution for dairy farms to make large CH₄ reductions.

Phosphorus (P) budgets for cropping systems provide insights for keeping soil P at optimal levels for crops while avoiding excess inputs. We quantified 12 years of P inputs (fertilizer and atmospheric deposition) and outputs (harvest and leaching losses) for replicated maize (Zea mays L.)-soybean (Glycine max L.)-wheat (Triticum aestivum) crop rotations under conventional, no-till, reduced input, and biologically based (organic without compost or manure) management systems at the Kellogg Biological Station LTAR site in southwest Michigan. Conventional, no-till, and reduced input systems were fertilized between 13 and 50 kg P ha^-1 depending on year. Soil test phosphorus (STP) was measured at 0- to 25-cm depth every autumn. Leached P was measured as dissolved P in the soil solution sampled beneath the rooting depth and combined with modeled percolation. Fertilization and harvest were the predominant P fluxes in the fertilized systems, whereas only harvest dominated P flux in the unfertilized organic system. Leaching losses were minor terms in the budgets, but leachate concentrations were nevertheless close to the range of concern for downstream eutrophication. Over the 12-year study period, the organic system exhibited a negative P balance (-82.0 kg P ha^-1), coinciding with suboptimal STP levels, suggesting a need for P supplementation. In contrast, the fertilized systems showed positive P balances (mean: 70.1 kg P ha^-1) with STP levels well above agronomic optima. Results underscore the importance of tailored P management strategies to sustain crop productivity while mitigating environmental impacts.

The range and density of one of North America's most destructive and invasive mammalian species, wild pigs (Sus scrofa), has expanded rapidly over the past several decades. Alongside this growth, their fecal contamination of surface waters has impaired water quality through significantly increased levels of pathogenic bacteria, raising concerns over the potential for zoonotic disease transmission. Significant remediation of these water quality impacts has been shown as a result of reductions in wild pig populations due to control efforts; however, the duration of these remediation effects as populations rebound remains unclear. Our study sought to determine the longevity of water quality remediation resulting from wild pig population control efforts. We found that median concentrations of Escherichia coli and fecal coliform (CFU/100 mL) increased by 746% and 159% in the year following the conclusion of removal efforts, resulting in median concentrations of 79% and 159% greater than those observed prior. We also found increased public health risk, with samples exceeding E. coli and fecal coliform guidelines 10% and 12% more often than pre-removal, respectively. While further research into wild pig population dynamics and fecal contamination is necessary, we conclude that ongoing population control efforts may be necessary to remediate water quality impacts and public health risks associated with invasive wild pigs.

Gypsum (CaSO₄·2H₂O) is increasingly used to bind P to soil on agricultural fields, which mitigates eutrophication caused by runoff of excess PO₄ ^3- fertilizers into adjacent aquatic environments. Gypsum also binds dissolved organic matter (DOM) to soil particles. Gypsum that gets into fresh water after field applications may result in enhanced particle formation by DOM flocculation and alter C transfer in rivers draining agricultural catchments. We tested the potential effects of gypsum additions on DOM cycling by adding concentrated gypsum solution into river water before subjecting it to controlled mixing to increase particle collisions and flocculation. Gypsum addition increased the amount of suspended particulate matter in river water three to four times higher than in controls without gypsum. The flocs contained a relatively high amount of minerogenic particles. Gypsum-induced flocculation removed colored dissolved organic matter which, together with removal of minerogenic particles, may result in increased water clarity. Gypsum addition and the associated changes in the DOM pool did not affect microbial growth or DOM processing, suggesting that flocculation did not target the labile fraction of the DOM pool. While acknowledging that the responses detected in our study might depend on the region, we propose that the changes in riverine DOM cycling caused by gypsum application results in either no changes or slightly positive changes to the water quality of the rivers and should not be considered an obstacle for eutrophication prevention using gypsum applications.

Agricultural runoff often contains P in dissolved and sediment-bound forms, decreasing surface water quality. No-till and cover cropping conservation practices have been recommended for reducing erosion and nutrient loss from cropping systems. The overall aims of this study were to characterize and evaluate the effects of fertilizer (placement and source) and cover crop management on P speciation in surface runoff sediments and source soil. In 2014, a field-scale experiment was established in a no-till, corn (Zea mays L.)-soybean (Glycine max L.) cropping system with two cover crop treatments (with and without a winter crop; winter wheat [Triticum aestivum L.], rapeseed [Brassica napus L.], hairy vetch [Vicia villosa Roth], winter triticale [×Triticosecale Wittm.], and cereal rye [Secale cereale L.]) and three P fertilizer management treatments (no P, fall broadcast diammonium phosphate, and spring subsurface injected ammonium polyphosphate). Phosphorus fractionation in the source soil collected in the fall of 2019 and sediment samples collected throughout 2020 were analyzed using a modified sequential P extraction method to evaluate the cumulative effects of imposing the treatment factors over 5 years. The direct P speciation was done using X-ray absorption near edge structure spectroscopy. The indirect P speciation (fractionation) results showed that the management practices affected the exchangeable, organic matter-associated, and Fe-bound P fractions in sediments and the exchangeable and residual fractions in source soil. Direct P speciation results showed a depletion of Fe-associated P in soil and sediment from cover crop treatment, suggesting that Fe-associated P species were affected by cover crops. Changes in soil and runoff sediment P speciation would change the proportions and forms of soluble and particulate P in runoff sediments and may influence P bioavailability in aquatic ecosystems. Developing P fertilizer and cropping system management options with an understanding of soil P transformations helps maintain environmental sustainability.

Global solid waste generation is expected to double by 2050 from the present annual level of 2.01 metric ton. Traditional biowaste treatment methods, such as landfilling and incineration, cannot meet the need to deal with gigantic amounts of waste and reduce environmental harm. This review critically evaluates existing sustainable waste management strategies highlighting their role in transitioning to a "reuse and recovery" paradigm. Sustainable waste management refers to conserving resources and protecting human health, society, and the environment. In this context, this review examines the current advancements and potential trends in using widely available biowaste in novel applications to produce key biofuels (such as biogas and biodiesel) and resources such as corrosion inhibitors, asbestos-free brake pads, nutrient-rich functional foods, bio-cement, bio-based fertilizer, and biodegradable plastic. Among these, biowaste-to-energy conversion (e.g., biogas production) and biodegradable plastic synthesis emerge as particularly impactful strategies due to their scalability and potential to address both waste reduction and resource recovery goals. The strategic utilization of biowaste resources into novel products holds significant promise in mitigating sustainability problems, offering renewable alternatives that are biodegradable and free of harmful additives.