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Surface water contaminants, including both conventional contaminants (e.g., nutrients, trace elements) and emerging contaminants (e.g., pesticides, pharmaceuticals) are heavily influenced by urban and rural land use practices. The goal of the study was to characterize the influence of watershed land use practices on surface water quality. Specific objectives were to (1) identify and quantify the type and concentration of nutrients, trace elements, pesticides, pharmaceuticals and personal care products in four watersheds and (2) understand potential sources of contamination based on the watershed's land cover and land use characteristics (i.e., oil and gas, urban, mining, agriculture). Monthly polar organic chemical integrative samples and water grab samples were collected from March-October 2022. The results showed that surface water quality varied by location, season, and flood condition Specifically, aluminum (mean = 758 μg L -1 ) and iron (mean = 1130 μg L -1 ) exceeded chronic aquatic life water quality criteria in the agricultural watershed, while imidacloprid exceeded the chronic criteria limit for freshwater invertebrates in both the urban (mean = 5.96 ng L -1 ) and agricultural (mean = 4.72 ng L -1 ) watersheds. Sulfate concentrations (mean = 666 mg L -1 ) also exceeded ambient water quality criteria in the watershed with a high activity of mining. This study provides important steps for developing a comprehensive understanding of land use impacts on contaminant presence and concentration in surface waters, improved understanding of the implications to non-target species, and necessary water treatment processes to ensure a safe water supply., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Tiffany L Messer reports financial support was provided by National Science Foundation. Tiffany L Messer reports financial support was provided by University of Kentucky Center for Appalachian Research in Environmental Sciences. Emily Nottingham Byers reports financial support was provided by National Science Foundation. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Per- and polyfluoroalkyl substances (PFAS) have been detected ubiquitously throughout the environment. Wastewater treatment plants (WWTPs) have been identified as potential hotspots for the introduction of PFAS into the environment. Therefore, the occurrence, transformation, and transport of 18 PFAS in two WWTPs with varying treatment processes, prevailing land uses, and during two distinct time periods were investigated. Polar Organic Chemical Integrative Samplers (POCIS) were installed at two WWTPs in Central Kentucky during April and July of 2022. PFAS concentrations typically increased from influent to effluent at both WWTPs, regardless of wastewater treatment processes, but changes in surface water concentrations from upstream to downstream of the effluent mixing zones varied. Both WWTPs discharged the 18 PFAS at higher loads than received, indicating prevalent transformation of PFAS precursors and non-measured PFAS analytes into measurable PFAS. Nearly all measured PFAS persisted in aqueous (86-98%) compartments rather than sediment or biosolids (2-14%). All biosolids had low content of PFAS with the dominant compound being PFOS (1.59-2.60 ng/g). Based on recent US EPA proposed maximum contaminant levels, hazard indexes for drinking water were exceeded in effluent and downstream surface waters at both WWTPs. The WWTP located in a heavily developed area and downstream from a firefighting training facility, had significantly higher concentrations of most PFAS species at most monitoring sites and was less impacted by sampling period compared to the WWTP located in a moderately developed, pastured area. Findings support the importance of WWTPs and land use practices as contributing to PFAS impact to downstream ecosystems along with potentially increasing strains on downstream drinking water source waters in regions that are surface water dependent., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Tiffany Messer reports administrative support, equipment, drugs, or supplies, statistical analysis, and travel were provided by United States Geological Survey, U.S. Department of Agriculture, and National Science Foundation. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

The use of wetlands as a treatment approach for nitrogen in runoff is a common practice in agroecosystems. However, nitrate is not the sole constituent present in agricultural runoff and other biologically active contaminants have the potential to affect nitrate removal efficiency. In this study, the impacts of the combined effects of four common veterinary antibiotics (chlortetracycline, sulfamethazine, lincomycin, monensin) on nitrate-N treatment efficiency in saturated sediments and wetlands were evaluated in a coupled microcosm/mesocosm scale experiment. Veterinary antibiotics were hypothesized to significantly impact nitrogen speciation (e.g., nitrate and ammonium) and nitrogen uptake and transformation processes (e.g., plant uptake and denitrification) within the wetland ecosystems. To test this hypothesis, the coupled study had three objectives: 1. assess veterinary antibiotic impact on nitrogen cycle processes in wetland sediments using microcosm incubations, 2. measure nitrate-N reduction in water of floating treatment wetland systems over time following the introduction of veterinary antibiotic residues, and 3. identify the fate of veterinary antibiotics in floating treatment wetlands using mesocosms. Microcosms containing added mixtures of the veterinary antibiotics had little to no effect at lower concentrations but stimulated denitrification potential rates at higher concentrations. Based on observed changes in the nitrogen loss in the microcosm experiments, floating treatment wetland mesocosms were enriched with 1000 μg L -1 of the antibiotic mixture. Rates of nitrate-N loss observed in mesocosms with the veterinary antibiotic enrichment were consistent with the microcosm experiments in that denitrification was not inhibited, even at the high dosage. In the mesocosm experiments, average nitrate-N removal rates were not found to be impacted by the veterinary antibiotics. Further, veterinary antibiotics were primarily found in the roots of the floating treatment wetland biomass, accumulating approximately 190 mg m -2 of the antibiotic mixture. These findings provide new insight into the impact that veterinary antibiotic mixtures may have on nutrient management strategies for large-scale agricultural operations and the potential for veterinary antibiotic removal in these wetlands.

The practice of using therapeutic and prophylactic veterinary antibiotics in livestock farming is a worldwide phenomenon. Over the last decade, there has been a growing concern of antibiotic residues entering the environment via animal manure. Similar studies have focused on the occurrence and biological effects of antibiotics in land-applied animal feedlots; however, limited research has been conducted on the occurrence and persistence of antibiotics in animal feedlots. Therefore, the objective of this study was to evaluate antibiotic persistence, fate, and transport in surface water runoff and feedlot sediment in feedlot pens with livestock either receiving or not receiving antibiotic treatments through injection and feed. The two antibiotics (tylosin and monensin) added to animal feed were observed to persist in the soil environment for more than 30 days along with injected florfenicol. Monensin (5.6× higher) and tylosin (20× higher) were significantly higher in livestock pens receiving antibiotics compared to livestock pens not receiving the antibiotics. Further, rainfall was observed to significantly impact soil surface concentrations of florfenicol. Other antibiotics administrated by injection were not observed to statistically increase in concentrations in runoff or feedlot sediment. Our findings emphasize antibiotics administered in feedlots have the potential to persist and remain in feedlot sediment and runoff, particularly in instances of regular administration in feed., (© 2023 The Authors. Journal of Environmental Quality © 2023 American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America.)

Mesocosm and microcosm experiments were conducted to explore the applicability of floating treatment wetlands (FTWs), an ecologically based management technology, to remove neonicotinoid insecticides and nitrate from surface water. The mesocosm experiment evaluated three treatments in triplicate over a 21-d period. Floating treatment wetland mesocosms completely removed nitrate-N over the course of the experiment even when neonicotinoid insecticides were present. At the completion of the experiment, 79.6% of imidacloprid and degradation byproducts and 68.3% of thiamethoxam and degradation byproducts were accounted for in the water column. Approximately 3% of imidacloprid and degradation byproducts and 5.0% of thiamethoxam and degradation byproducts were observed in above-surface biomass, while ∼24% of imidacloprid and degradation byproducts, particularly desnitro imidacloprid, and <0.1% of thiamethoxam and degradation byproducts were found in the below surface biomass. Further, 1 yr after the experiments, imidacloprid, thiamethoxam, and degradation byproducts persisted in biomass but at lower concentrations in both the above- and below-surface biomass. Comparing the microbial communities of mature FTWs grown in the presence and absence of neonicotinoids, water column samples had similar low abundances of nitrifying Archaeal and bacterial amoA genes (below detection to 10 4  ml -1 ) and denitrifying bacterial nirK, nirS, and nosZ genes (below detection to 10 5  ml -1 ). Follow-up laboratory incubations found the highest denitrification potential activities in FTW plant roots compared with water column samples, and there was no effect of neonicotinoid addition (100 ng L -1 ) on potential denitrification activity. Based on these findings, (a) FTWs remove neonicotinoids from surface water through biomass incorporation, (b) neonicotinoids persist in biomass long-term (>1 yr after exposure), and (c) neonicotinoids do not adversely affect nitrate-N removal via microbial denitrification., (© 2022 The Authors. Journal of Environmental Quality © 2022 American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America.)

Efforts to improve water quality of eutrophic ponds often involve implementing changes to watershed management practices to reduce external nutrient loads. While this is required for long-term recovery and prevention, eutrophic conditions are often sustained through the recycling of internal nutrients already present within the waterbody. In particular, internal phosphorus bound to organic material and adsorbed to sediment has the potential to delay lake recovery for decades. Thus, pond and watershed management techniques are needed that not only reduce external nutrient loading but also mitigate the effects of internal nutrients already present. Therefore, our objective was to demonstrate a biological and chemical approach to remove and sequester nutrients present and entering an urban retention pond. A novel biological and chemical management technique was designed by constructing a 37 m 2 (6.1 m × 6.1 m) floating treatment wetland coupled with a slow-release lanthanum composite inserted inside an airlift pump. The floating treatment wetland promoted microbial denitrification and plant uptake of nitrogen and phosphorus, while the airlift pump slowly released lanthanum to the water column over the growing season to reduce soluble reactive phosphorus. The design was tested at the microcosm and field scales, where nitrate-N and phosphate-P removal from the water column was significant (α = 0.05) at the microcosm scale and observed at the field scale. Two seasons of field sampling showed both nitrate-N and phosphate-P concentrations were reduced from 50 μg L -1 in 2020 to <10 μg L -1 in 2021. Load calculations of incoming nitrate-N and phosphate-P entering the retention pond from the surrounding watershed indicate the presented biological-chemical treatment is sustainable and will minimize the effects of nutrient loading from nonpoint source pollution., (Published by Elsevier Ltd.)

Currently little is known of newer pesticide classes and their occurrence and persistence in recreational lakes. Therefore, the objectives of this study were to (1) assess average pesticide concentrations and loadings entering recreational lakes in three mixed land use watersheds throughout the growing season, (2) evaluate pesticide persistence longitudinally within the lakes, and (3) perform an ecotoxicity assessment. Six sampling campaigns were conducted at three lakes from April through October 2018 to measure the occurrence and persistence during pre, middle, and post growing season. Polar organic chemical integrative samplers (POCIS) were placed in streams near lake inlets and monthly samples were collected for analysis of twelve pesticides. Additional monthly grab water samples were taken at each POCIS location and at the midpoint and outlet of each lake. All pesticide samples were analyzed using liquid chromatography/tandem mass spectrometry (LC/MS/MS) and individual pesticide loading rates were determined. Occurrence and persistence of specific pesticides were significantly different between lakes in varying watershed land uses. Specifically, the recreational lake receiving predominately urban runoff had the highest load of pesticides, likely in the form of biocides, entering the waterbody. Concentrations of imidacloprid exceeded acute and chronic invertebrate levels for 11% and 61% of the sampling periods, respectively, with the recreational lake receiving predominately urban runoff having the most occurrences. Findings from this study are critical for preventing and mitigating potential effects of pesticides, specifically applied as biocides in urban landscapes, from entering and persisting in recreational lakes., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

A wide variety of antibiotics and other pharmaceuticals are used in livestock production systems and residues passed to the environment, often unmetabolized, after use and excretion. Antibiotic residues may be transported from manure-treated soils via runoff and are also capable of reaching surface and groundwater systems through a variety of pathways. The occurrence and persistence of antibiotics in the environment is a concern due to the potential for ecological effects and proliferation of environmental antibiotic resistance in pathogenic organisms. In the present study, the occurrence and seasonal variation of 24 commonly-used veterinary antibiotics was evaluated in surface water adjacent to several livestock production systems using Polar Organic Chemical Integrative Samplers (POCIS). Uptake rates for all compounds, nine of which have not been previously reported, were measured in the laboratory to permit estimation of changes in the time-weighted average (TWA) antibiotic concentrations during exposure. The antibiotics detected in POCIS extracts included sulfadimethoxine, sulfamethoxazole, trimethoprim, sulfamerazine, sulfadiazine, lincomycin, erythromycin, erythromycin anhydro- and monensin. The maximum TWA concentration belonged to sulfadiazine (25 ng/L) in the August-September sampling period and coincided with the highest number of precipitation events. With the exception of monensin that showed an increase in concentration over the stream path, none of the detected antibiotics were prescribed to livestock at the facility. The detection of antibiotics not prescribed by the facility may be attributable to the environmental persistence of previously used antibiotics, transfer by wind from other nearby livestock production sites or industrial uses, and/or the natural production of some antibiotics., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Accurate prediction of Escherichia coli contamination in surface waters is challenging due to considerable uncertainty in the physical, chemical and biological variables that control E. coli occurrence and sources in surface waters. This study proposes a novel approach by integrating hydro-climatic variables as well as animal density and grazing pattern in the feature selection modeling phase to increase E. coli prediction accuracy for two cascading dams at the US Meat Animal Research Center (USMARC), Nebraska. Predictive models were developed using regression techniques and an artificial neural network (ANN). Two adaptive neuro-fuzzy inference system (ANFIS) structures including subtractive clustering and fuzzy c-means (FCM) clustering were also used to develop models for predicting E. coli. The performances of the predictive models were evaluated and compared using root mean squared log error (RMSLE). Cross-validation and model performance results indicated that although the majority of models predicted E. coli accurately, ANFIS models resulted in fewer errors compared to the other models. The ANFIS models have the potential to be used to predict E. coli concentration for intervention plans and monitoring programs for cascading dams, and to implement effective best management practices for grazing and irrigation during the growing season., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Atrazine, one of the most widely used herbicides in the world, threatens human health along with terrestrial and aquatic biota. Recent reports have found atrazine in drinking water to be associated with increased birth defects and incidences of Non-Hodgkin's Lymphoma, with higher levels of significance from exposure to both atrazine and nitrate-N. The Midwest region of the United States, which includes Nebraska, is one of the leading regions for high nitrate-N concentrations and agrochemicals, including atrazine, in surface waters. Therefore, the objective of this study was to provide a case study for completing an environmental risk analysis for the potential exposure of atrazine and nitrate-N to ecosystems and humans through interaction with surface waters using two approaches: (1) Identify watersheds across Nebraska that were at risk for exceeding atrazine and nitrate-N maximum contaminant limits (MCLs) in surface water; and (2) Determine the specific times of year where risks were greatest. Factors were then analyzed using Geographic Information System (GIS) software to identify areas of high risk. Impairments for both nitrate-N and atrazine in the surface water were found predominately during the early growing season in the southeastern region of Nebraska, in watershed areas with the highest amount of corn production and annual precipitation. Further, the methodology developed in this study has the potential for application in regions with higher dependency on surface water to determine multiple agrochemical load influxes from upstream regions and evaluate other surface water contaminants during the same time periods., (Copyright © 2019 Elsevier Ltd. All rights reserved.)