Land application of wastewater effluent is beneficial for recharging groundwater aquifers and avoiding direct pollutant discharges to surface waters. However, the fate of non-regulated organic ...wastewater pollutants, such as pharmaceuticals and personal care products (PPCPs), in such wastewater reuse systems is understudied. Here, a 14-month study (October 2016 through December 2017) was conducted to evaluate the fate and potential risks of seven commonly used PPCPs in a local wastewater treatment plant (WWTP) and from 13 groundwater monitoring wells at a spray-irrigation site where effluent has been spray-irrigated since the early 1980s. Acetaminophen and trimethoprim were the most frequently detected (93%) PPCPs in WWTP influent, while in the effluent, caffeine and trimethoprim were detected most frequently (70%). Wastewater treatment generally reduced concentrations of acetaminophen and caffeine by >88%; however, some compounds had low removal or were present at higher concentrations in the effluent compared with influent (e.g. naproxen, sulfamethoxazole, trimethoprim and ofloxacin). Seasonal trends were observed, with higher PPCP concentrations in the WWTP influent and effluent in the winter. Risk calculations conducted on the wastewater effluent suggest that the risk posed by PPCPs that persisted in the effluent are medium to high to aquatic organisms. Detection frequencies of PPCPs were lower in groundwater samples compared to the effluent, with sulfamethoxazole (40%) and caffeine (32%) as the most frequently detected compounds. Similarly, average concentrations of PPCPs in groundwater were found to be nearly two orders of magnitude lower than concentrations in the effluent. Minimal seasonal influence was observed for groundwater samples. Human health risk assessments indicate that concentrations in groundwater, which is used as a drinking water source, appear to pose minimal risk.
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•7 pharmaceuticals were tracked through a wastewater treatment plant and reuse site.•Removal efficiencies through the treatment plant varied by season and by compound.•Pharmaceuticals posed a medium to high risk to aquatic ecosystem health.•Groundwater concentrations were ~2 orders of magnitude lower than those in effluent.•Pharmaceutical concentrations in groundwater posed minimal human health risk.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Cost-effective heat mitigation strategies are imperative for maintaining milk production and dairy farm profitability in the U.S. with projected climate change. This study investigated the ...cost-effectiveness of four heat abatement strategies, including Minimal (open barn or shading), Moderate (forced ventilation), High (fans and misting), and Intense (air conditioning). Heat stress and subsequent impacts on milk production per cow were predicted across nine climatic regions in the U.S. for early (2015 to 2034), mid (2045 to 2064) and late (2081 to 2100) 21st century, using downscaled climate projections. Heat abatements were used to adjust predicted milk production losses and illustrate the potential to reduce milk production losses due to heat stress. Economic analysis included a cost-benefit ratio calculation associated with the implementation of each heat abatement. Results showed that milk production losses were expected to accelerate across the U.S. at a mean rate of 174±7 kg/cow/decade, with the fastest rate in the Southeast region. Relative to Minimal heat abatement, Moderate, High, and Intense heat abatements increased annual milk production per cow by 3%, 4%, and 6% during early-21st century, 3%, 6%, and 11% during mid-21st century, and 3%, 8%, and 21% during late-21st century, respectively. The cost effectiveness of different heat abatement strategies generally increased with subsequently stronger heat abatements. In mid- and late-21st century, mean annual net values of High and Intense heat stress abatement implementation approached -$30 to $190 /cow and -$20 to $590 /cow, respectively, with the largest net annual benefit in late-21st century under Intense abatement. Findings from the study demonstrate the value of using downscaled climate projections to shed light on local and regional strategies to abate heat stress on cattle and mitigate potential milk production losses due to climate change.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The timing of manure application and placement of manure significantly affects manure nutrient use efficiency and the amount of nutrient lost from a field. Application of manure prior to a minimal ...precipitation period, and manure application through incorporation, reduces risks associated with nutrient loss through surface runoff. The current study aims to explore potential water quality impacts related to manure application strategies on the timing of application and approach (surface broadcasting or incorporation). The Soil and Water Assessment Tool (SWAT) was used to represent manure application scenarios and quantify potential water quality impacts in Susquehanna River Basin located in the Mid-Atlantic region of the United States. A baseline (business-as-usual) scenario was developed with manure application based on crop planting date and manure storage availability, and surface broadcasting as the application approach. The baseline was compared with a strategically timed manure application considering weather forecasting and manure incorporation. The strategic, weather-based manure application approach reduced TN and TP loading at the outlet by 4% and 6%, respectively. Manure incorporation simulations considering low-disturbance injection showed significant reduction of about 19% for TN and 44% for TP at the watershed outlet. Winter closure of manure application could reduce organic nutrient loss. Winter application of manure in 21% of row cropped areas (2% of whole watershed area) increased organic N and P loading by 10% and 4%, respectively, at watershed outlet.
•Application timing and placement is critical for increasing nutrient use efficiency.•Strategically timed manure application considering weather reduced nutrient loss.•Winter closure of manure application reduced risks from runoff nutrient loss.•Manure incorporation reduced runoff nutrient loss but increased nutrient leaching.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abstract
Nutrient and sediment transport exhibit strong spatial and temporal inequality, with a small percentage of locations and events contributing to the vast majority of total annual loads. The ...processes for determining how to reduce total annual loads at a watershed scale often target spatial, but not temporal, components of inequality. We introduce a framework using Lorenz Inequality and corresponding Gini Coefficient to quantify the temporal inequality of nutrient and sediment transport across the Chesapeake Bay watershed. This long-impaired, 166 000 km
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watershed has been federally mandated since 2010 to continually reduce nutrient and sediment loads reaching the Bay. Data were obtained for 108 sites in the Chesapeake Bay’s non-tidal network from 2010 to 2018. The Lorenz Inequality and Gini Coefficient analyses were conducted using daily-scale data for flow and loads of total nitrogen (TN), total phosphorus (TP), and total suspended sediment (TSS) at each gaging station. We leverage these results to create a ‘temporal targeting framework’ that identifies periods of time and corresponding flow conditions that must be targeted to achieve desired or mandated load reduction goals across the watershed. Among the 108 sites, the degree of temporal inequality for TP and TSS (0.37–0.98) was much greater than for flow and TN (0.29–0.77), likely due to the importance of overland versus baseflow in the transport pathways of the respective constituents. These findings stress the importance of informed design and implementation of best management practices effective in ‘hot moments,’ and not just ‘hot spots,’ across impaired watersheds to achieve and maintain water quality restoration goals. The ‘temporal targeting framework’ detailed in this manuscript provides a useful and convenient method for watershed planners to create low- and high-flow load targeting tables specific to a watershed and constituent.
Quantitative risk assessments of pollution and data related to the effectiveness of mitigating best management practices (BMPs) are important aspects of nonpoint source pollution control efforts, ...particularly those driven by specific water quality objectives and by measurable improvement goals, such as the total maximum daily load (TMDL) requirements. Targeting critical source areas (CSAs) that generate disproportionately high pollutant loads within a watershed is a crucial step in successfully controlling nonpoint source pollution. The importance of watershed simulation models in assisting with the quantitative assessments of CSAs of pollution (relative to their magnitudes and extents) and of the effectiveness of associated BMPs has been well recognized. However, due to the distinct disconnect between the hydrological scale in which these models conduct their evaluation and the farm scale at which feasible BMPs are actually selected and implemented, and due to the difficulty and uncertainty involved in transferring watershed model data to farm fields, there are limited practical applications of these tools in the current nonpoint source pollution control efforts by conservation specialists for delineating CSAs and planning targeting measures. There are also limited approaches developed that can assess impacts of CSA-targeted BMPs on farm productivity and profitability together with the assessment of water quality improvements expected from applying these measures. This study developed a modeling framework that integrates farm economics and environmental aspects (such as identification and mitigation of CSAs) through joint use of watershed- and farm-scale models in a closed feedback loop. The integration of models in a closed feedback loop provides a way for environmental changes to be evaluated with regard to the impact on the practical aspects of farm management and economics, adjusted or reformulated as necessary, and revaluated with respect to effectiveness of environmental mitigation at the farm- and watershed-levels. This paper also outlines steps needed to extract important CSA-related information from a watershed model to help inform targeting decisions at the farm scale. The modeling framework is demonstrated with two unique case studies in the northeastern United States (New York and Vermont), with supporting data from numerous published, location-specific studies at both the watershed and farm scales. Using the integrated modeling framework, it can be possible to compare the costs (in terms of changes required in farm system components or financial compensations for retiring crop lands) and benefits (in terms of measurable water quality improvement goals) of implementing targeted BMPs. This multi-scale modeling approach can be used in the multi-objective task of mitigating CSAs of pollution to meet water quality goals while maintaining farm-level economic viability.
► Modeling-framework developed to help mitigate pollution and maintain farm viability. ► The approach helped evaluate feasibility of mitigation-measures at the farm level. ► Model identified attributes of high-pollution areas to inform targeting decisions.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Regulatory watershed mitigation programs typically emphasize widespread adoption of best management practices (BMPs) to meet total maximum daily load (TMDL) goals. To comply with the Chesapeake Bay ...TMDL, jurisdictions must develop watershed implementation plans (WIPs) to determine the number and type of BMPs to implement. However, the spatial resolution of the bay‐level model used to determine these load reduction goals is so coarse that the regulatory plan cannot consider heterogeneity in local conditions, which affects BMP effectiveness. Using the Topo‐SWAT modification of the Soil and Water Assessment Tool (SWAT), we simulated two BMP adoption scenarios in the Spring Creek watershed in central Pennsylvania to determine if leveraging fine‐scale spatial heterogeneity to place BMPs could achieve the same (or better) nutrient and sediment reduction at a lower cost than the state‐level WIP BMP adoption recommendations. Topo‐SWAT was initialized with detailed land use and management practice information, systematically calibrated, and validated against 12 yr of observed data. After determining individual BMP cost effectiveness, results were ranked to design a cost‐effective BMP adoption scenario that achieved equal or greater load reduction as the WIP scenario for 74% of the cost using eight management‐based BMPs: no‐till, manure injection, cover cropping, riparian buffers, land retirement, manure application timing, wetland restoration, and nitrogen management (15% less N input). Because watersheds of this size typically represent the smallest modeling unit in the Chesapeake Bay Model, results demonstrate the potential to use watershed models with finer inference scales to improve recommendations for BMP implementation under the Chesapeake Bay TMDL.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Although many agricultural watersheds rely heavily on riparian buffer adoption to meet water quality goals, design and management constraints in current policies create adoption barriers. Based on ...focus group feedback, we developed a flexible buffer design paradigm that varies buffer width, vegetation, and harvesting. Sixteen years of daily‐scale nutrient and sediment loads simulated with the Soil and Water Assessment Tool (SWAT) were coupled to the three‐zone Riparian Ecosystem Management Model (REMM) to compare the effectiveness of traditional, policy‐based buffer designs with designs that are more flexible and integrate features important to local farmers. Buffer designs included (i) 10 m grass, (ii) 15 m grass, (iii) 15 m deciduous trees, (iv) 30 m grass and trees, (v) 30 m grass and trees with trees harvested every 3 yr, and (vi) 30 m grass and trees with grass harvested every year. Allowing harvesting in one zone of the buffer vegetation (either trees or grasses) minimally affected water quality, with annual average percent reductions differing by <5% (p > .05; 76–78% for total nitrogen TN, 51–55% for total phosphorus TP, and 68% for sediment). Under the highest input loading conditions, buffers with lower removal efficiencies removed more total mass than did buffers with high removal efficiencies. Thus, by focusing on mass reduction in addition to percent reduction, watershed‐wide buffer implementation may be better targeted to TN, TP, and sediment reduced. These findings have important implications for informing flexible buffer design policies and enhanced placement of buffers in watersheds impaired by nutrient and sediment.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Acetaminophen (ACT), sulfapyridine (SPY), ibuprofen (IBP) and docusate (DCT) are pharmaceuticals with widespread usage that experience incomplete removal in wastewater treatment systems. While ...further removal of these pharmaceuticals from wastewater effluent is desired prior to beneficial reuse, additional treatment technologies are often expensive and energy intensive. This study evaluated the ability of biochar produced from cotton gin waste (CG700) and walnut shells (WS800) to remove four pharmaceuticals (ACT, SPY, IBP, and DCT) from aqueous solution. Physico-chemical properties of the biochars were characterized by Brunauer-Emmett-Teller (BET) analysis, scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FT-IR), and zeta potential. The increased pyrolysis temperature during the production of WS800 led to an increase in the specific surface area and increased dehydration of the biochar represented by the loss of the OH-group. Fixed-bed column experiments were performed to determine the difference in removal efficiency between the biochars and elucidate the effects of biochar properties on the adsorption capacity for the pharmaceuticals of interest. Results showed that CG700 had a greater affinity for removing DCT (99%) and IBP (50%), while WS800 removed 72% of SPY and 68% of ACT after 24 h. Adsorption was influenced by the solution pH, surface area, net charge, and functional groups of the biochars. The mechanisms for removal included pore filling and diffusion, hydrophobic interactions, hydrogen bonding, and π-π electron donor acceptor interactions. To conduct predictive modeling of the column breakthrough curves, the Thomas, Adams-Bohart, and Yoon-Nelson models were applied to the experimental data. Results demonstrated that these models generally provided a poor fit for the description of asymmetrical breakthrough curves. Overall, the results demonstrate that biochars from cotton gin waste and walnut shells could be used as cost-effective, environmentally friendly alternatives to activated carbon for the removal of pharmaceuticals from aqueous solutions.
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•Properties of biochar produced from two agricultural wastes were characterized.•Each biochar was evaluated for removal of four selected pharmaceuticals from water.•Biochar produced from cotton gin waste removed 99% of docusate and 50% of ibuprofen.•Walnut shell-derived biochar removed 72% of sulfapyridine and 68% of acetaminophen.•Biochar properties, solution pH, and pharmaceutical properties affected the results.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Recent interest in tracking environmental benefits of conservation practices on agricultural watersheds throughout the United States has led to the development of the U.S. Department of Agriculture’s ...(USDA) Conservation Effects Assessment Project (CEAP). The purpose of CEAP is to assess environmental benefits derived from implementing various USDA conservation programs for cultivated, range, and irrigated lands. Watershed scale, hydrologic simulation models such as the Soil and Water Assessment Tool (SWAT) will be used to relate principal source areas of contaminants to transport paths and processes under a range in climatic, soils, topographic, and land use conditions on agricultural watersheds. To better understand SWAT’s strengths and weaknesses in simulating streamflow for anticipated applications related to CEAP, we conducted a study to evaluate the model’s performance under a range of climatic, topographic, soils, and land use conditions. Hydrologic responses were simulated on five USDA Agricultural Research Service watersheds that included Mahantango Creek Experimental Watershed in Pennsylvania and Reynolds Creek Experimental Watershed in Idaho in the northern part of the United States, and Little River Experimental Watershed in Georgia, Little Washita River Experimental Watershed in Oklahoma, and Walnut Gulch Experimental Watershed in Arizona in the south. Model simulations were performed on a total of 30 calibration and validation data sets that were obtained from a long record of multigauge climatic and streamflow data on each of the watersheds. A newly developed autocalibration tool for the SWAT model was employed to calibrate eleven parameters that govern surface and subsurface response for the three southern watersheds, and an additional five parameters that govern the accumulation of snow and snowmelt runoff processes for the two northern watersheds. Based on a comparison of measured versus simulated average annual streamflow, SWAT exhibits an element of robustness in estimating hydrologic responses across a range in topographic, soils, and land use conditions. Differences in model performance, however, are noticeable on a climatic basis in that SWAT will generally perform better on watersheds in more humid climates than in desert or semidesert climates. The model may therefore be better suited for CEAP investigations in wetter regions of the eastern part of the United States that are predominantly cultivated than the dryer regions of the West that are more characteristically rangeland.
Over‐the‐counter and prescription medications are routinely present at detectable levels in surface and groundwater bodies. The presence of these emerging contaminants has raised both environmental ...and public health concerns, particularly when the water is used for drinking either directly or with additional treatment. However, the frequency of occurrence, range of concentrations, and potential human health risks are not well understood, especially for groundwater supplies. Private wells are often not tested for contaminants regulated by drinking water standards and are even less frequently tested for emerging contaminants. By partnering with the Pennsylvania Master Well Owner Network, water samples were collected from 26 households with private wells in the West Branch of the Susquehanna River basin in central Pennsylvania in winter 2017. All samples were analyzed for six pharmaceuticals (acetaminophen, ampicillin, naproxen, ofloxacin, sulfamethoxazole, and trimethoprim) and one over‐the‐counter stimulant (caffeine). At least one compound was detected at each site. Ofloxacin and naproxen were the most and least frequently detected compounds, respectively. Concentrations from the groundwater wells were higher than those of nearby surface water samples. However, risk calculations revealed that none of the concentrations measured in groundwater samples posed significant human health risk. A simple, physicochemical‐based modeling approach was used to predict pharmaceutical transport from septic absorption field to groundwater and further elucidate variations in detection frequencies. Findings indicate that although septic tanks may act as contaminant sources for groundwater wells, the human health impacts from trace‐level pharmaceuticals that may be present are likely minimal.
Core Ideas
Twenty‐six private wells in Pennsylvania were sampled for seven pharmaceutical compounds.
At least one compound was detected per groundwater sample at ng L−1 to μg L−1 levels.
On average, concentrations were higher in private wells than in nearby surface water.
Concentrations were generally highest for the most frequently detected compounds.
Concentrations were low enough that no adverse human health effects are expected.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
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