Stereoselective Degradation of Estradiol and Trenbolone Isomers in Alluvial Sediment

Stereoisomers of estradiol (E2) or trenbolone (TB) can occur together in the environment receiving human or livestock wastes. However, the effect of their co-occurrence on persistence has not been well elucidated. A sandy and a silt loam sediment were used to establish microcosms with α- and β-isomers of E2 or TB spiked individually and together. Sediments were sampled periodically and analyzed for E2 and TB isomers and their transformation products using derivatization gas chromatography–mass spectrometry. Results showed that stereoselective degradation was significant for E2 in both sediments and TB in the sandy sediment with β-isomers decaying more rapidly than α-isomers. In the sandy sediment containing limited natural organic carbon and nutrients, co-occurrence of both isomers of either E2 or TB decreased the dissipation rates. In the silt loam sediment with abundant organic matter and nutrients, the decay rates of both isomers were not changed in the presence of the other isomer. Estrone (E1) and trendione (TD) were detected as primary metabolites of E2 and TB isomers, respectively. The formation and decay profiles of E1 were similar in both sediments with 92–100% of E2 transformed to E1. The TD profiles were different across sediments with ∼100% of TB transformed to TD except in the sandy sediment where 51–60% of 17α-TB was converted to TD. These results indicate that the transformation processes of steroid hormone are stereoselective in sediment and co-occurrence of stereoisomers can prolong steroid persistence and thus pose greater environmental risk

Data_Sheet_1_Extraction, analysis, and occurrence of per- and polyfluoroalkyl substances (PFAS) in wastewater and after municipal biosolids land application to determine agricultural loading.docx

Given the ubiquitous detection of per- and polyfluoroalkyl substances (PFAS) within numerous soil and water environmental compartments, there is a need for global understanding of current methodologies for extracting water, solids, polar organic chemical integrative samplers (POCIS), and plant tissue for these substances. This study provides details of several current extraction methods, demonstrates the use of POCIS in monitoring these compounds in a wastewater environment, and provides evidence of detectable levels of certain PFAS compounds within Midwestern municipalities and agroecosystems. Validated extraction procedures help characterize occurrence and release of 18 PFAS in a midwestern wastewater treatment plant (WWTP), surface water, runoff after land application of biosolids to agricultural test plots, infiltration into topsoil, and uptake by grain sorghum. Of the compounds measured, 14 PFAS were detected at least at one sampling site or type. The average total (Σ PFAS) dissolved phase time-weighted average (TWA) concentration in wastewater influent, effluent and in the upstream and downstream effluent mixing zone (EMZ) sites in the receiving stream, respectively, were 27.9, 132, 37.7, and 71.4 ng L−1. Long-chain PFAS dominated most of the aqueous compartments, and perfluoroalkyl acids (PFAAs) occurred in the WWTP and receiving surface waters. Total Σ14 PFAS measured in municipal biosolids applied to soils were 22.9 ng g−1 dw with long-chain PFAS comprising 77.5% of the cumulative PFAS mass. Perfluorooctanesulfonic acid (PFOS) was the most abundant compound detected in biosolids at the highest concentration (9.40 ng g−1 dw). Accumulation in WWTP biosolids was estimated to occur at a rate of 72.8 g day−1 dw based on the difference between influent and effluent time weighted average concentrations. PFAS were detected in both surface soil and runoff after land application of biosolids, but also in control plots consistent with background PFAS contamination. PFAS concentrations in surface runoff decreased over time from plots treated with biosolids. These results provide evidence of the introduction of PFAS to agroecosystems from wastewater effluent and land application of biosolids in the Midwest.</p

Dechlorinating Chloroacetanilide Herbicides by Dithionite-Treated Aquifer Sediment and Surface Soil

The prevalent use of chloroacetanilide herbicides has resulted in nonpoint contamination of some groundwater and surface water. We determined the efficacy of dithionite-treated sediment and soils to transform chloroacetanilides. When used alone, dithionite rapidly dechlorinates chloroacetanilides in water, with the following order of reactivity:  propachlor > alachlor > acetochlor > metolachlor. Stoichiometric release of chloride occurs during reaction with dithionite. and thiosulfate herbicide derivatives are produced. Treating aquifer sediment with dithionite reduces native Fe(III), creating a redox barrier of Fe(II)-bearing minerals and surface-bound Fe(II). Washing the reduced sediment (buffered with citrate-bicarbonate) with oxygen-free water removed Fe(II) and excess dithionite and no alachlor transformation was observed. In contrast, a dithionite-treated surface soil, rich in clay and iron, effectively dechlorinated alachlor after washing. Exposing alachlor to aquifer sediment treated with dithionite in potassium carbonate buffer (pH 8.5−9.0) produced dechlorinated alachlor as the major degradation product. Our results provide proof-of-concept that dechlorination of chloroacetanilide herbicides by dithionite and dithionite-treated aquifer sediment and soil is a remediation option in natural environments where iron-bearing minerals are abundant

Evaluating Youth-Led Citizen Science for Improved Monitoring of Domestic Well Water Quality in Nebraska

Domestic well water quality is unregulated, infrequently monitored, and increasingly impacted by contamination, which seriously affects safe use for drinking, especially in intensively agricultural states such as Nebraska. In this study, rural Nebraska high school students and teachers who participated in a youth-led educational citizen science project received hands-on training in domestic well water construction, sampling, and vulnerability as well as basic knowledge about groundwater flow and availability. Students independently collected groundwater samples and measured atrazine, nitrate, chloride, calcium hardness, pH, and electrical conductivity using commercial test kits and a multiparameter probe. To evaluate the comparability of student test measurements, replicate samples were collected and tested for the same parameters in a university laboratory. Similarities and differences between student tests and laboratory measurements were expressed in terms of the coefficient of determination (R2) and the absolute difference in averages (|Δave|). A comparison of the results between the youth citizen scientists and laboratory results proved good comparability for many tests while revealing the need for improvement in instruction, calibration, and use of the test probe and kits. Additional parameters measured in the split samples underscore the value of using citizen science sampling for evaluating the vulnerability of domestic well water quality to contamination. In the first three years of student sampling, laboratory results show that nitrate concentrations in over one-quarter of Nebraska domestic wells sampled more than safe levels for drinking water, and many wells sampled have concentrations of geogenic arsenic, manganese, and uranium above drinking water standards. This study shows how youth-led citizen science can improve monitoring coverage, provide data, and integrate local communities to better evaluate and respond to growing concerns over domestic well water quality

Natural Reactive Iron Dynamics in the Agricultural Soil of Semiarid to Arid Systems

Quantifying redox-driven changes in iron chemistry in irrigated semiarid to arid soils and their relevance for the availability of nutrients and contaminants is critical for global food security. Data across three growing seasons and two different soil types in semiarid to arid climates indicate site-independent peaks of reactive iron in soil aligned with peaks in irrigation events. The reactive iron formed during irrigation was short-lived, and the concentration was back at baseline during harvest. The significant (p < 0.01) increase of reactive iron ranging from 1589.0 ± 172.3 to 1898.0 ± 201.1 μg g–1 over the growing season triggered by reducing conditions due to transient water infiltration resulted in the mobilization of organic soil carbon and affected the mobility and plant availability of nitrogen, uranium, and arsenic. Porewater samples collected during irrigation events demonstrated increasing iron concentrations over time and positively correlated (p < 0.05) with arsenic and uranium levels. Geogenic arsenic mobilization into soil porewater during peak irrigation events contained significantly (p < 0.01) higher (∼90%) reduced inorganic arsenic species. Crop tissue analysis indicated that roots contained the highest concentrations of trace elements, followed by shoots and grains. Coupled (bio)­geochemical redox cycles of iron, nutrients, and contaminants seem to play a critical but so far less recognized role for crop production in irrigated agroecosystems of semiarid to arid systems

Competitive ¹⁵N Kinetic Isotope Effects of Nitrogenase-Catalyzed Dinitrogen Reduction

Biological N2 fixation is achieved under ambient conditions by enzymatic catalysis. The enzyme nitrogenase has been studied extensively, but the N2 chemical reduction step is, by far, not rate limiting and hard to examine. A new method was developed that allows studying the reduction transition state within the enzyme's complex kinetic cascade by means of the 15N kinetic isotope effect on the reaction's second-order rate constant, V/K. A value of 1.7% ± 0.2% was measured

Bioavailability and Fate of Sediment-Associated Progesterone in Aquatic Systems

The environmental fate and bioavailability of progesterone, a steroid hormone known to cause endocrine-disrupting effects in aquatic organisms, is of growing concern due to its occurrence in the environment in water and sediment influenced by wastewater treatment plant and paper mill effluents, as well as livestock production. The objective of this study was to evaluate the fate of progesterone in two natural sediments and the corresponding alteration of gene expression in three steroid-responsive genes; vitellogenin, androgen receptor and estrogen receptor alpha. When exposed to progesterone-spiked sand, fathead minnows (<i>Pimephales promelas</i>) exhibited significant reductions in the expression of vitellogenin and androgen receptor expression. In contrast, fish exposed to progesterone associated with the silty loam sediment did not show a biological response at 7 days and only realized a significant reduction in vitellogenin. In both sediments, progesterone degradation resulted in the production of androgens including androsteinedione, testosterone, and androstadienedione, as well as the antiestrogen, testolactone. Differences in compound fate resulted in organism exposure to different suites of metabolites either in water or associated with the sediment. Results from this study suggest that environmental progestagens will lead to defeminization at environmentally relevant concentrations, and that exposure is influenced by sediment properties

Transformation of Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) by Permanganate

The chemical oxidant permanganate (MnO4−) has been shown to effectively transform hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) at both the laboratory and field scales. We treated RDX with MnO4− with the objective of quantifying the effects of pH and temperature on destruction kinetics and determining reaction rates. A nitrogen mass balance and the distribution of reaction products were used to provide insight into reaction mechanisms. Kinetic experiments (at pH ∼ 7, 25 °C) verified that RDX−MnO4− reaction was first-order with respect to MnO4− and initial RDX concentration (second-order rate: 4.2 × 10−5 M−1 s−1). Batch experiments showed that choice of quenching agents (MnSO4, MnCO3, and H2O2) influenced sample pH and product distribution. When MnCO3 was used as a quenching agent, the pH of the RDX−MnO4− solution was relatively unchanged and N2O and NO3− constituted 94% of the N-containing products after 80% of the RDX was transformed. On the basis of the preponderance of N2O produced under neutral pH (molar ratio N2O/NO3 ∼ 5:1), no strong pH effect on RDX−MnO4− reaction rates, a lower activation energy than the hydrolysis pathway, and previous literature on MnO4− oxidation of amines, we propose that RDX−MnO4− reaction involves direct oxidation of the methylene group (hydride abstraction), followed by hydrolysis of the resulting imides, and decarboxylation of the resulting carboxylic acids to form N2O, CO2, and H2O

Impact of Sediment on Agrichemical Fate and Bioavailability to Adult Female Fathead Minnows: A Field Study

Precipitation induced runoff is an important pathway for agrichemicals to enter surface water systems and expose aquatic organisms to endocrine-disrupting compounds such as pesticides and steroid hormones. The objectives of this study were to investigate the distribution of agrichemicals between dissolved and sediment-bound phases during spring pulses of agrichemicals and to evaluate the role of suspended sediment in agrichemical bioavailability to aquatic organisms. To accomplish these objectives, suspended sediment and water samples were collected every 3 days from a field site along the Elkhorn River, located at the downstream end of a heavily agricultural watershed, and were screened for 21 pesticides and 21 steroids. Adult female fathead minnows (<i>Pimephales promelas</i>) were exposed in field mesocosms to river water containing varying sediment loads. Changes in organism hepatic gene expression of two estrogen-responsive genes, vitellogenin (<i>VTG</i>) and estrogen receptor alpha (<i>ERα</i>), as well as the androgen receptor (<i>AR</i>) were analyzed during periods of both low and high river discharge. Trends in agrichemical concentrations of both the dissolved and sediment phases as a function of time show that, while sediment may act as both a source and a sink for agrichemicals following precipitation events, the overall driver for molecular defeminization in this system is direct exposure to the sediment-associated compounds. This study suggests that endocrine disrupting effects observed in organisms in turbid water could be attributed to direct exposure of contaminated sediment

Occurrence and Potential Biological Effects of Amphetamine on Stream Communities

The presence of pharmaceuticals, including illicit drugs in aquatic systems, is a topic of environmental significance because of their global occurrence and potential effects on aquatic ecosystems and human health, but few studies have examined the ecological effects of illicit drugs. We conducted a survey of several drug residues, including the potentially illicit drug amphetamine, at 6 stream sites along an urban to rural gradient in Baltimore, Maryland, U.S.A. We detected numerous drugs, including amphetamine (3 to 630 ng L–1), in all stream sites. We examined the fate and ecological effects of amphetamine on biofilm, seston, and aquatic insect communities in artificial streams exposed to an environmentally relevant concentration (1 μg L–1) of amphetamine. The amphetamine parent compound decreased in the artificial streams from less than 1 μg L–1 on day 1 to 0.11 μg L–1 on day 22. In artificial streams treated with amphetamine, there was up to 45% lower biofilm chlorophyll a per ash-free dry mass, 85% lower biofilm gross primary production, 24% greater seston ash-free dry mass, and 30% lower seston community respiration compared to control streams. Exposing streams to amphetamine also changed the composition of bacterial and diatom communities in biofilms at day 21 and increased cumulative dipteran emergence by 65% and 89% during the first and third weeks of the experiment, respectively. This study demonstrates that amphetamine and other biologically active drugs are present in urban streams and have the potential to affect both structure and function of stream communities