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USGS2016

Understanding the hydrologic impacts of wastewater treatment plant discharge to shallow groundwater: Before and after plant shutdown

Effluent-impacted surface water has the potential to transport not only water, but wastewater-derived contaminants to shallow groundwater systems. To better understand the effects of effluent discharge on in-stream and near-stream hydrologic conditions in wastewater-impacted systems, water-level changes were monitored in hyporheic-zone and shallow-groundwater piezometers in a reach of Fourmile Creek adjacent to and downstream of the Ankeny (Iowa, USA) wastewater treatment plant (WWTP). Water-level changes were monitored from approximately 1.5 months before to 0.5 months after WWTP closure. Diurnal patterns in WWTP discharge were closely mirrored in stream and shallow-groundwater levels immediately upstream and up to 3 km downstream of the outfall, indicating that such discharge was the primary control on water levels before shutdown. The hydrologic response to WWTP shutdown was immediately observed throughout the study reach, verifying the far-reaching hydraulic connectivity and associated contaminant transport risk. The movement of WWTP effluent into alluvial aquifers has implications for potential WWTP-derived contamination of shallow groundwater far removed from the WWTP outfall.

Iowa↗

USGS2019

De facto reuse and disinfection by-products in drinking water systems in the Shenandoah River watershed

De facto reuse is increasingly being studied among the variety of stressors that are relevant to drinking water systems that obtain their source water from surface waters. De facto reuse may influence the levels and types of precursors relevant to formation of disinfection by-products (DBPs) in surface water systems. DBPs such as trihalomethanes (THMs) and haloacetic acids (HAAs) have been associated with bladder cancer and other health concerns in people who use drinking water provided by public water systems (PWSs). In this study, we used compliance monitoring data from conventional surface water PWSs in the Shenandoah River watershed to evaluate the relationship between de facto reuse in the watershed with DBP formation in those systems. The Shenandoah River watershed was selected for this study because it has a relatively small group of PWSs that draw their source water from surface waters in the watershed, the majority of whom treat their water using chlorine, and are less likely to have confounding factors (such as complex distribution systems or lengthy residence times) than other watersheds. We found that concentrations of THM4 and HAA5 increase in drinking water systems as de facto reuse increases in their source waters and that the relation is observed at both annual average and low streamflow conditions (annual average and low streamflow increases were statistically significant for THM4 with p values of 0.027 and 0,021, respectively). In addition, using a t -test, we found that a 1% level of de facto reuse was associated with significantly higher levels of THM4 and HAA5 ( p < 0.05) under annual average streamflow conditions. While the concentrations of HAA5 were also higher under annual average and low streamflow conditions, we did not find that they achieved a level of a significant difference. Results from this research will be helpful to operators of PWSs and other researchers and stakeholders with an interest in water reuse and DBPs.

Virginia↗

USGS2020

Landfill leachate contributes per-/poly-fluoroalkyl substances (PFAS) and pharmaceuticals to municipal wastewater

Widespread disposal of landfill leachate to municipal sewer infrastructure in the United States calls for an improved understanding of the relative organic-chemical contributions to the wastewater treatment plant (WWTP) waste stream and associated surface-water discharge to receptors in the environment. Landfill leachate, WWTP influent, and WWTP effluent samples were collected from three landfill-WWTP systems and compared with analogous influent and effluent samples from two WWTPs that did not receive leachate. Samples were analyzed for 73 per-/poly-fluoroalkyl substances (PFAS), 109 pharmaceuticals, and 21 hormones and related compounds. PFAS were detected more frequently in leachate (92%) than in influent (55%). Total PFAS concentrations in leachate (93,100 ng/L) were more than ten times higher than in influent (6,950 ng/L), and effluent samples (3,730 ng/L). Concentrations of bisphenol A; the nonprescription pharmaceuticals cotinine, lidocaine, nicotine; and the prescription pharmaceuticals amphetamine, carisoprodol, pentoxifylline, and thiabendazole were an order of magnitude higher in landfill leachate than WWTP influent. Leachate load contributions for PFAS (0.78 to 31 g/d), bisphenol A (0.97 to 8.3 g/d), and nonprescription (2.0 to 3.1 g/d) and prescription (0.48 to 2.5 g/d) pharmaceuticals to WWTP influent were generally low (<10 g/d) for most compounds because of high influent-to-leachate volumetric ratios (0.983). No clear differences in concentrations were apparent between effluents from WWTPs receiving landfill leachate and those that did not receive landfill leachate.

Environmental Science: Water Research & Technology↗

USGS2022

Improving gas-derived parameterization of groundwater using free phase gas measurements

Dissolved atmogenic gasses in groundwater provide significant information about recharge conditions, flowpath, and age. Free phase gas in aquifers is largely ignored in these analyses and there is a lack of quantitative analysis for gas flux mechanisms. Many related fields encountering multiphase flow acknowledge that the presence of bubbles allows for the rapid exsolution of dissolved gasses and volatile compounds through diffusive and polar forces. By measuring the mass flow of the exsolved gas at a spring, coupled with compositional analysis in the free and dissolved phases, we show that not incorporating the effects of the free gas phase of bubbling springs introduces error in the estimation of total gas quantities, particularly light noble gasses. This can significantly affect the corresponding estimation of noble gas temperature (NGT) and apparent age. We examine the transport of free and dissolved gas from the recharge zone, using water level variation data, to the discharge location where the gases are measured. This technique of using the free gas phase for assessing aquifer dynamics will improve groundwater conceptual models, particularly in karstic aquifers where rapid fluctuations in the water table facilitate the development of excess air, generating multiphase spring discharge.

Environmental Science: Water Research & Technology↗

USGS2022

Modeling risk dynamics of contaminants of emerging concern in a temperate-region wastewater effluent-dominated stream

Wastewater effluent-dominated streams are becoming increasingly common worldwide, including in temperate regions, with potential impacts on ecological systems and drinking water sources. We recently quantified the occurrence/spatiotemporal dynamics of pharmaceutical mixtures in a representative temperate-region wastewater effluent-dominated stream (Muddy Creek, Iowa) under baseflow conditions and characterized relevant fate processes. Herein, we quantified the ecological risk quotients (RQs) of 19 effluent-derived contaminants of emerging concern (CECs; including: 14 pharmaceuticals, 2 industrial chemicals, and 3 neonicotinoid insecticides) and 1 run-off-derived compound (atrazine) in the stream under baseflow conditions, and estimated the probabilistic risks of effluent-derived CECs under all-flow conditions ( i.e. , including runoff events) using stochastic risk modeling. We determined that 11 out of 20 CECs pose medium-to-high risks to local ecological systems ( i.e. , algae, invertebrates, fish) based on literature-derived acute effects under measured baseflow conditions. Stochastic risk modeling indicated decreased, but still problematic, risk of effluent-derived CECs ( i.e. , RQ ≥ 0.1) under all-flow conditions when runoff events were included. Dilution of effluent-derived chemicals from storm flows thus only minimally decreased risk to aquatic biota in the effluent-dominated stream. We also modeled in-stream transport. Thirteen out of 14 pharmaceuticals persisted along the stream reach (median attenuation rate constant k < 0.1 h −1 ) and entered the Iowa River at elevated concentrations. Predicted and measured concentrations in the drinking water treatment plant were below the human health benchmarks. This study demonstrates the application of probabilistic risk assessments for effluent-derived CECs in a representative effluent-dominated stream under variable flow conditions (when measurements are less practical) and provides an enhanced prediction tool transferable to other effluent-dominated systems.

Iowa↗

USGS2025

Comparing contaminants of emerging concern and microbial signatures of wastewater treated by membrane bioreactor and oxidation ditch methods

Membrane bioreactors (MBRs) are an attractive option for upgrades to aging wastewater treatment infrastructure across the United States (U.S.) because they have a relatively small footprint and can handle various wastewater loading conditions. However, little is known regarding the efficiency with which MBRs can reduce contaminants of emerging concern (CECs) and microbial loads, or how they influence the microbiome of wastewater effluent. In 2022, we collected nine paired samples of primary treated effluent (PRI), secondary effluent treated by oxidation ditches (OXI), and secondary effluent treated by MBR from a facility in Minnesota, U.S. Samples were analyzed for CECs including 4 alkylphenol ethoxylates, 6 bisphenol analogues, 20 hormones, 110 pharmaceuticals, and 82 pesticides as well as heterotrophic bacteria counts (HPC) and microbiome communities. Except for pesticides, total sample concentrations of CEC classes in OXI and MBR effluents were similar and lower compared to PRI ( p < 0.01). Pesticide concentrations were similar among all treatments. HPC was lower in MBR, compared to OXI, in 67% of samples. Despite limited differences in CEC signatures, differences in the microbiome between the two secondary treatments were observed. OXI showed more distinct differences in bacterial operational taxonomic unit (OTU) presence from PRI, compared to MBR. Relations between some contaminant groups ( e.g. , pharmaceuticals, bisphenols) and effluent microbiomes were observed, though most correlated with PRI effluent. Results from our study indicate that MBR is as effective as OXI at producing high-quality effluent and offers a viable alternative to conventional secondary treatment methods. This full-scale study provides data that helps fill knowledge gaps related to MBR performance outside of lab or benchtop experiments and direct comparison to OXI treatment.

Environmental Science: Water Research & Technology↗

USGS2008

Environmental presence and persistence of pharmaceuticals: An overview

Emerging contaminants (ECs) in the environment – that is, chemicals with domestic, municipal, industrial, or agricultural sources that are not commonly monitored but may have the potential for adverse environmental effects – is a rapidly growing field of research. The use of “emerging” is not intended to infer that the presence of these compounds in the environment is new. These chemicals have been released into the environment as long as they have been in production or, in the case of hormones and other endogenous compounds, since the rise of animal life. What is emerging is the interest by the scientific and lay communities in the presence of these chemicals in the environment, the analytical capabilities required for detection, and the subtle effects that very small concentrations of these chemicals appear to have on aquatic biota. In December 2006, Environmental Science & Technology devoted an entire special issue (volume 40, number 23) to the topic of ECs, illustrating the increased interest in the subject. Within the EGs, one particular class that has seen a substantial increase in research over the past 10 years is pharmaceuticals and personal-care products (PPCPs). This increased research interest can be demonstrated by several means, including requests for proposals from funding agencies, but the clearest indication of a focused effort to understand the introduction, transformation, and potential health and environmental effects of PPCPs and ECs, in general, is the number of published reports. This increase can be shown by examining six environmental journals that regularly publish PPCP-related papers – Chemosphere , Environmental Science & Technology , Environmental Toxicology and Chemistry , Science of the Total Environment , Water Research , and Water Science and Technology . In 1998 there were 22 papers published on pharmaceuticals, antibiotics, or drugs in these 6 journals; by 2006, this number increased sixfold to 132 papers (Figure 1.1). This growth can be attributed to a number of factors. The presence of pharmaceuticals in surface-water samples from Europe and the United States was documented in several sentinel papers. These ground-breaking works encouraged other scientists to examine the rivers, streams, lakes, and reservoirs in their regions for such chemicals. In addition, the intense public attention paid to news reports on the environmental detections of these chemicals and possible effects of aquatic life has made this issue visible to the wastewater-treatment, drinking-water treatment, and regulatory communities. This has driven the funding bodies associated with these communities to fund studies or request proposals that address the presence, fate, and effects of PPCPs in aquatic systems. The release of the first comprehensive reconnaissance of pharmaceuticals and other wastewater contaminants in the United States provides an example of the intense media interest in this topic. Within 6 days on online publication of this study, 72 newspapers across the United States had published articles describing the results, either locally written or based on international media syndicate reports. There also was substantial concurrent coverage by local and national radio and television outlets, including the Cable News Network, ABC World News Tonight , and National Public Radio. A substantial fraction of these news stories may be attributable to press releases and media briefings prior to publication. However, the interest by television and print journalists in reporting the results of a peer-reviewed journal article to the general public was motivated by the recognition that describing the presence of PPCPs in water supplies would be of interest to the public. To better convey the results of the study published by Koplin et al. to the public, a separate general-interest fact sheet was published to summarize the important points of the study. Because PPCPs are commonly and widely used by individuals, there is likely a preexisting, personal identification with these compounds that does not occur for the wide range of other organic and inorganic contaminants whose presence in the environment has previously been described. This greater public “name recognition” makes itself known through the media to the regulatory and technical community and has prompted interest in sponsoring research that defines the composition and concentrations of PPCPs in potential sources and their fate and effects following relase into the environment. Independent of the drivers that potentially fuel the interest in studies of PPCPs, it is clear that PPCP research has grown beyond surface-water studies to examine issues such as: • Presence in other matrices, such as groundwater, landfill leachates, sediments, and biosolids. • Environmental transport and fate in surface water, groundwater, and soils amended with reclaimed water or biosolids. • PPCP source elucidation, such as wastewater treatment plant (WWTP) effluents, confined animal feeding operations (CAFOs), and aquaculture. • Removal during wastewater and drinking-water treatment. • Effects on aquatic ecosystems, terrestrial ecosystems, and human health. The chapters in this book provide an extensive examination of current environmental pharmaceutical research and are divided into three sections: “Occurrence and Analysis of Pharmaceuticals in the Environment,” “Environment Fate and Transformations of Veterinary Pharmaceuticals,” and “treatment of Pharmaceuticals in Drinking Water and Wastewater.” The purpose of this introductory overview chapter is to outline current (2004-2006) knowledge about the presence and concentration of PPCPs as described in the published literature. Previous reviews should be consulted for discussions on pre-2004 publications. Those reviews will provide the reader with a comprehensive introduction to the topic of PPCPs in the environment. This chapter describes the sources of PPCPs and other organic contaminants often associated with human wastewater into the environment, the range of concentrations present in various environmental compartments, and the potential routes of removal/sequestration. An overview of the sources and fate of veterinary pharmaceuticals will be discussed in Chapter 5, “Fate and Transport of Veterinary Medicines in the Soil Environment.”

Book chapter↗

USGS2023

Predicted aquatic exposure effects from a national urban stormwater study

A multi-agency study of 438 organic and 62 inorganic chemicals measured in urban stormwater during 50 total runoff events at 21 sites across the United States demonstrated that stormwater discharges can generate localized, aquatic exposures to extensive contaminant mixtures, including organics suspected to cause adverse aquatic-health effects. The aggregated risks to multiple aquatic trophic levels (fish, invertebrates, plants) of the stormwater mixture exposures, which were documented in the national study, were explored herein by calculating cumulative ratios of organic-contaminant in vitro exposure–activity cutoffs (∑ EAR ) and health-benchmark-weighted cumulative toxicity quotients (∑ TQ ). Both risk assessment approaches indicated substantial (moderate to high) risk for acute adverse effects to aquatic organisms across multiple trophic levels (fish, macroinvertebrates, non-vascular/vascular plants) at or near stormwater discharge points across the United States. The results are interpreted as potential orders of magnitude underestimates of actual aquatic risk in stormwater control wetlands or in the immediate vicinity of such discharges to surface-water receptors, because the 438 organic-compound analytical space assessed in this study is orders of magnitude less than the 350 000 parent compounds estimated to be in current commercial use globally and the incalculable chemical-space of potential metabolites and degradates.

Environmental Science: Water Research and Technolo↗

USGS2023

Exposures and potential health implications of contaminant mixtures in linked source water, finished drinking water, and tapwater from public-supply drinking water systems in Minneapolis/St. Paul area, USA

Continued improvements in drinking-water quality characterization and treatment/distribution infrastructure are required to address the expanding number of documented environmental contaminants. To better understand the variability in contaminant exposures from the drinking water resource (surface and groundwater), through the distribution process, to the point-of-use (tapwater), in 2019 a synoptic assessment of broad chemical exposures was conducted in system-specific source waters, finished drinking water and service-area tapwater from 10 drinking water treatment facilities in the greater Minneapolis/St. Paul area of Minnesota, United States. Source water, finished water (collected pre-distribution in the treatment facility), and tapwater samples were analyzed for 465 unique organic compounds, 34 inorganic constituents, and 3 field parameters as well as in vitro estrogen, androgen, and glucocorticoid bioactivities. Mixtures of organic and inorganic contaminants were prevalent in source water, finished water, and tapwater samples, indicating the continued need for broad assessments of mixed contaminant exposures to characterize potential drinking-water human health outcomes. Contaminant concentrations were similar among drinking water sources and no exceedances of Environmental Protection Agency maximum contaminant level(s) (MCL) were observed in any treated sample (finished water or tapwater) in this study. No treated sample contained estrogenic, androgenic, or glucocorticoid activity at concentrations that may cause adverse human health effects. However, there were multiple exceedances of non-enforceable MCL goal(s) (MCLG), and other health advisories combined with frequent exceedances of benchmark-based hazard indices in both finished water and tapwater samples. These results indicate that exposure to contaminant mixtures is a potential public health concern underscoring our continued efforts to assess contaminant mixture exposures at the drinking-water point of consumption using a broad analytical scope.

Minnesota↗

USGS2025

Tapwater-contaminant mixtures and risk in a biofuel-facility impacted private-well community

We assessed private-well drinking water (DW) at the point of use ( i.e. , tapwater, TW) within a rural Nebraska community around a state-closed biofuel facility, which used pesticide-treated corn seed as feedstock for ethanol production. Organic (485), inorganic (34), and microbial (13) analytes were assessed at 15 locations in June 2022, to evaluate the relative contribution of facility-consistent pesticides (seed-treatment fungicides and insecticides) to overall TW-contaminant exposures and predicted human-health risks. Thirty-three organics (12 pesticides) and 28 inorganics were detected, the former including the fungicide sedaxane, insecticide chlorantraniliprole, and multiple neonicotinoid insecticides/degradates, all consistent with seed treatment and respective biofuel-facility waste. Assessment of pesticides only at extant point-of-use (POU) treatment taps at three sites demonstrated complete elimination of all TW-pesticide detections. Based on detection of maximum pesticide concentrations in a home located downstream along a creek capturing facility runoff, pesticides only were assessed in January 2023 again at this home and at three adjacent locations, confirming results at the former and documenting decreasing TW-pesticide concentrations, including neonicotinoids, with increasing distance from the creek. Human-health DW benchmarks are not available for many detected pesticides, including the detected fungicide and insecticides, but precautionary screening levels were exceeded frequently due to multiple inorganics. The results indicate that exposures to multiple (median: 4.5; range: 1–7) co-occurring TW contaminants of potential human-health concern are common, warranting consideration of point-of-entry or POU treatment(s) throughout the community to reduce or eliminate unrecognized exposures to TW contaminants, including facility-associated pesticides in down-gradient locations. More broadly, results emphasize the importance of continued characterization of private-TW exposures, employing a environmentally informative analytical scope, to identify and mitigate risks of unrecognized exposures in private-well-dependent rural communities.

Nebraska↗

USGS2011

Partnership of Environmental Education and Research-A compilation of student research, 1999-2008

The U.S. Geological Survey (USGS) Tennessee Water Science Center and the College of Engineering and Technology at Tennessee State University developed a Partnership in Environmental Education and Research (PEER) to support environmental research at TSU and to expand the environmental research capabilities of the USGS in Tennessee. The PEER program is driven by the research needs to better define the occurrence, fate, and transport of contaminants in groundwater and surface water. Research in the PEER program has primarily focused on the transport and remediation of organic contamination in karst settings. Research conducted through the program has also expanded to a variety of media and settings. Research areas include contaminant occurrence and transport, natural and enhanced bioremediation, geochemical conditions in karst aquifers, mathematical modeling for contaminant transport and degradation, new methods to evaluate groundwater contamination, the resuspension of bacteria from sediment in streams, the use of bioluminescence and chemiluminescence to identify the presence of contaminants, and contaminant remediation in wetlands. The PEER program has increased research and education opportunities for students in the College of Engineering, Technology, and Computer Science and has provided students with experience in presenting the results of their research. Students in the program have participated in state, regional, national and international conferences with more than 140 presentations since 1998 and more than 40 student awards. The PEER program also supports TSU outreach activities and efforts to increase minority participation in environmental and earth science programs at the undergraduate and graduate levels. TSU students and USGS staff participate in the TSU summer programs for elementary and high school students to promote earth sciences. The 2007 summer camps included more than 130 students from 20 different States and Washington DC.

Tennessee↗

USGS2003

Selected applications of hydrologic science and research in Maryland, Delaware, and Washington, D.C., 2001-2003

One of the roles of the U.S. Geological Survey (USGS) is to provide reliable water data and unbiased water science needed to describe and understand the Nation?s water resources. This fact sheet describes selected techniques that were used by the USGS to collect, transmit, evaluate, or interpret data, in support of investigations that describe the quantity and quality of water resources in Maryland (MD), Delaware (DE), and the District of Columbia (D.C.). These hydrologic investigations generally were performed in cooperation with universities, research centers, and other Federal, State, and local Government agencies. The applications of hydrologic science and research that were selected for this fact sheet were used or tested in the MD-DE-DC District from 2001 through 2003, and include established methods, new approaches, and preliminary research. The USGS usually relies on standard methods or protocols when conducting water-resources research. Occasionally, traditional methods must be modified to address difficult environmental questions or challenging sampling conditions. Technologies developed for other purposes can sometimes be successfully applied to the collection or dissemination of water-resources data. The USGS is continually exploring new ways to collect, transmit, evaluate, and interpret data. The following applications of hydrologic science and research illustrate a few of the recent advances made by scientists working for and with the USGS.

Fact Sheet↗

USGS2024

Integrated science for the study of microplastics in the environment—A strategic science vision for the U.S. Geological Survey

Executive Summary Evidence of the widespread occurrence of microplastics throughout our environment and exposure to humans and other organisms over the past decade has led to questions about the possibility of health hazards and mitigation of exposures. This document discusses nanoplastics as well as microplastics (referred to solely as microplastics); the microplastics have a range from 1 micrometer to 5 millimeters (1 μm–5 mm) in length, whereas the nanoplastics are less than 1 μm in length (sidebar ES1). A myriad of environmental exposure pathways with microplastics to humans and wildlife, including ingestion, inhalation, and bodily absorption, are likely to exist. A growing body of evidence has documented bioaccumulation of microplastics in tissues and organs of humans and wildlife, benthic community effects, and potential nutritional and reproductive effects in some wildlife species. Understanding if or when environmental exposures pose a health risk is complicated by the diversity of microplastic sizes, morphologies, polymer types, and chemicals added during manufacturing or sorbed from the environment; ongoing challenges in analytical methods used to detect, quantify, and characterize microplastics and associated chemicals in our ecosystems; and the fact that ecotoxicological studies regarding microplastics are still in their infancy. Therefore, the study of environmental exposures and potential related health hazards of microplastics to the public and wildlife is a One Health (sidebar ES2) research topic that necessitates integrated science approaches. A better understanding of the sources, pathways, fate, and biological effects of microplastics has become a priority of the Federal Government, State governments, Tribes, stakeholders, and the public. Examples of Federal and State microplasticfocused legislation and programs to prioritize microplastic research and reduction include the Federal Microbead-Free Waters Act of 2015, California Senate Bills 1422 and 1263 (2018), the U.S. Environmental Protection Agency (EPA) Trash Free Waters Program, the National Institute of Standards and Technology’s Microplastic and Nanoplastic Metrology project, and Minnesota’s microplastic project. With its unique expertise and capabilities, the U.S. Geological Survey (USGS) is well positioned to help fill some of the most important microplastic science gaps. This strategic science vision document for microplastics identifies current (2023) microplastic science gaps and prioritizes research relevant to the mission, expertise, and capabilities of the USGS. It is intended for USGS scientists and stakeholders to use as a starting point for planning, prioritizing, and designing collaborative environmental microplastic science. Many of the microplastic science gaps and priorities are scalable, from local to national, and thus, can be made commensurate with available funding and evolving analytical and field tools, laboratory capacity, and stakeholder needs. Current (2023) or future research by academia and other Federal or State agencies, and Tribes may be aimed at some of the same microplastic science gaps identified in this document. Therefore, this document can be used as an information resource to maximize strengths and capabilities and minimize redundancy in communication and collaboration.

Circular↗

USGS2003

Arsenic speciation and reactivity in poultry litter

Recent U.S. government action to lower the maximum concentration levels (MCL) of total arsenic (As) (10 ppb) in drinking water has raised serious concerns about the agricultural use of As-containing biosolids such as poultry litter (PL). In this study, solid-state chemical speciation, desorbability, and total levels of As in PL and long-term amended soils were investigated using novel synchrotron-based probing techniques (microfocused (μ) synchrotron X-ray fluorescence (SXRF) and μ-X-ray absorption near-edge structure (XANES) spectroscopies) coupled with chemical digestion and batch experiments. The total As levels in the PL were as high as ≈50 mg kg - 1 , and As(II/III and V) was always concentrated in abundant needle-shaped microscopic particles (≈20 μm × 850 μm) associated with Ca, Cu, and Fe and to a lesser extent with S, Cl, and Zn. Post-edge XANES features of litter particles are dissimilar to those of the organo-As(V) compound in poultry feed (i.e., roxarsone), suggesting possible degradation/transformation of roxarsone in the litter and/or in poultry digestive tracts. The extent of As desorption from the litter increased with increasing time and pH from 4.5 to 7, but at most 15% of the total As was released after 5 d at pH 7, indicating the presence of insoluble phases and/or strongly retained soluble compounds. No significant As accumulation (<15 mg kg - 1 ) was found in long-term PL-amended agricultural surface soils. This suggests that As in the PL may have undergone surface and subsurface transport processes. Our research results raise concerns about long-term PL amendment effects on As contamination in surrounding soil−water environments.

Environmental Science & Technology↗

USGS1995

Occurrence of selected pesticides and their metabolites in near-surface aquifers of the midwestern United States

The occurrence and distribution of selected pesticides and their metabolites were investigated through the collection of 837 water-quality samples from 303 wells across the Midwest. Results of this study showed that five of the six most frequently detected compounds were pesticide metabolites. Thus, it was common for a metabolite to be found more frequently in groundwater than its parent compound. The metabolite alachlor ethanesulfonic acid (alachlor-ESA; 2-[(2,6-diethylphenyl)(methoxymethyl)amino]-2-oxoethanesulfonic acid) was detected almost 10 times as frequently and at much higher concentrations than its parent compound alachlor (2-chloro-2‘,6‘-diethyl- N -(methoxymethyl)acetamide). The median detectable atrazine (2-chloro-4-ethylamino-6- isopropylamino- s -triazine) concentration was almost half that of atrazine residue (atrazine plus the two atrazine metabolites analyzed). Cyanazine amide [2-chloro-4-(1-carbamoyl-1-methylethylamino)-6-ethylamino- s -triazine] was detected almost twice as frequently as cyanazine (2-chloro-4-ethylamino-6-methylpropionitrileamino- s -triazine). Results show that information on pesticide metabolites is necessary to understand the environmental fate of pesticides. Consequently, if pesticide metabolites are not quantified, the effects of chemical use on groundwater quality would be substantially underestimated. Thus, continued research is needed to identify major degradation pathways for all pesticides and to develop analytical methods to determine their concentrations in water and other environmental media.

Environmental Science & Technology↗

USGS2022

Science mission requirements for a globally ranging, riserless drilling vessel for U.S. Scientific Ocean Drilling

Through the collection and analysis of shallow and deep subseafloor sediments, rocks, fluids, and life, scientific ocean drilling has enriched our understanding of the complex Earth system. Among other achievements, scientific ocean drilling has documented the history of Earth’s climate, the waxing and waning of polar ice sheets, the past changes in ocean and atmospheric circulation, the existence and function of microbial life in the subseafloor, the compositional variations in Earth’s crust and underlying mantle, and the physical and chemical processes acting at subduction zones, including those associated with tsunamigenic earthquakes. Over the decades, more than 12,000 articles that depend on analyses of scientific ocean drilling samples and geophysical data have been published, many detailing breakthrough contributions to global knowledge about the Earth system. Approximately 45% of these publications were led by U.S.-affiliated authors (International Ocean Discovery Program Publication Services, 2021). Since the mid-1980s, the workhorse of this multidisciplinary, international research effort has been the riserless D/V JOIDES Resolution, operated by Texas A&M University with funding from the U.S. National Science Foundation (NSF). D/V JOIDES Resolution has conducted the vast majority of scientific ocean drilling expeditions and collected most of the scientific cores over that period, including 82% of the expeditions and 93% of the cores in the last decade alone, despite being one of three platforms that is operated within the International Ocean Discovery Program. However, D/V JOIDES Resolution is approaching the end of its useful life. With a strong commitment to continue scientific ocean drilling beyond the end of the current phase, the community developed a document outlining the research frontiers that should be pursued. Exploring Earth by Scientific Ocean Drilling: 2050 Science Framework (Koppers and Coggon, 2020) describes seven scientific strategic objectives that focus on understanding interconnections within the Earth system and five flagship initiatives that integrate these objectives into long-term research efforts that address issues facing society. Additional elements in the 2050 Science Framework, including STEM education, workforce development, technology development, and innovative applications of data analytics, will advance the goals of scientific ocean drilling. Addressing the 2050 Science Framework also requires building partnerships with allied U.S. and international science programs and strengthening existing ones. To implement a significant portion of the 2050 Science Framework, the U.S. scientific community seeks to lease or acquire a newly built, globally ranging, state-of-the art, riserless drilling vessel. The many and varied technical and human resources requirements for successful accomplishment of scientific and educational goals summarized in this document and described in detail in the 2050 Science Framework require broad community input and careful consideration. Following receipt of NSF’s formal Request for Assistance to the United States Science Support Program (USSSP), the U.S. scientific ocean drilling community conducted a one-year exercise to identify its national scientific needs and priorities in order to determine the Science Mission Requirements (SMRs) presented here. This community effort included: (1) a U.S. community-wide survey to identify the specific operational and technical capabilities critical to addressing science in the 2050 Science Framework; (2) a series of online workshops focusing on critical capabilities identified by the survey; and (3) a large in-person workshop to synthesize the results of the survey and the virtual workshops (Appendix 1). The approach was designed to reach as many participants as possible. Overall, 278 survey responses were received from U.S. community members, representing 104 unique institutions from 39 states and the District of Columbia, and 137 unique individuals participated in the workshops (Appendix 2). The results of this effort comprise two classes of SMRs: Foundational Science Mission Requirements and Primary Science Mission Requirements. Foundational SMRs define minimum criteria for a new riserless drilling vessel that can address significant portions of the 2050 Science Framework. Primary SMRs build upon the Foundational SMRs and will create more robust science opportunities and data collection capabilities, will increase progress in addressing the 2050 Science Framework objectives, and will provide more real-time ship-to-shore interaction to improve science productivity, engagement, and outreach. Modern safety and environmental standards, including meeting standards to access protected waters such as exclusive economic zones, extended continental shelves, or high latitudes, while being cognizant of the vessel’s environmental footprint. Safe and efficient operations in global locations and in water depths from 70 m to 6000+ m, with total drill string length of at least 7000 m. High-quality core and data collection from a range of key subseafloor environments. Advanced heave compensation, dynamic positioning, and drill pipe stability. Modern mud and cement/casing systems. Critical onboard measurements for safety, operational decision-making, documentation of ephemeral properties, mission-specific science, and long-term science goals that extend beyond a single expedition. Designated and appropriate space for sample and data preservation. Highly skilled onboard personnel, including technical staff for curation and core handling; support for safety, time-sensitive, and critical shipboard measurements; computer support; equipment and instrument repair; application support; and data assurance. Primary Science Mission Requirements include: Flexible shipboard space for laboratories and on deck to ensure safe, successful implementation of diverse science objectives and operations. Minimizing contamination of recovered samples. Over-the-side capabilities for science-supporting technology (e.g., remotely operated vehicles, water- column sampling, sediment-water interface sampling). Downhole logging and measurements. Expanded borehole observatory capabilities. Reliable and consistent ship-to-shore communications. NSF’s investment in a new globally ranging, riserless drilling vessel will have a powerful economic multiplier effect, including the infusion of additional science support funds in the United States for training and research, the development of new technologies and tools, and the associated scientific and technical workforce development. The skills and knowledge gained through scientific ocean drilling are translatable to careers in fields such as sustainable energy development (e.g., geothermal and offshore wind), carbon sequestration, data management and cyberinfrastructure, biotechnology, communications, science education, policy, hazard mitigation, and environmental management. The United States is a leader in a well-established and internationally collaborative scientific ocean drilling community. A modern, globally ranging, riserless drilling vessel will allow the United States to expand its leadership position, address broad scientific questions that current capabilities preclude, and cultivate equitable international, multidisciplinary collaborations that will ensure scientific ocean drilling’s future success.

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USGS2004

Toward a scientifically rigorous basis for developing mapped ecological regions.

Despite the wide use of ecological regions in conservation and resource-management evaluations and assessments, a commonly accepted theoretical basis for ecological regionalization does not exist. This fact, along with the paucity of focus on ecological regionalization by professional associations, journals, and faculties, has inhibited the advancement of a broadly acceptable scientific basis for the development, use, and verification of ecological regions. The central contention of this article is that ecological regions should improve our understanding of geographic and ecological phenomena associated with biotic and abiotic processes occurring in individual regions and also of processes characteristic of interactions and dependencies among multiple regions. Research associated with any ecoregional framework should facilitate development of hypotheses about ecological phenomena and dominant landscape elements associated with these phenomena, how these phenomena are structured in space, and how they function in a hierarchy. Success in addressing the research recommendations outlined in this article cannot occur within an ad hoc, largely uncoordinated research environment. Successful implementation of this plan will require activities--coordination, funding, and education--that are both scientific and administrative in nature. Perhaps the most important element of an infrastructure to support the scientific work of ecoregionalization would be a national or international authority similar to the Water and Science Technology Board of the National Academy of Sciences.

Environmental Management↗

USGS2015

Applications of optical sensors for high-frequency water-quality monitoring and research

The recent commercial availability of in-situ optical sensors, together with new techniques for data collection and analysis, provides the opportunity to monitor a wide range of water-quality constituents over time scales during which environmental conditions actually change. Traditional approaches for data collection (daily to monthly discrete samples) are often limited by high sample collection, processing, and analytical costs, difficult site access, and logistical challenges, particularly for long-term sampling at a large number of sites. Optical sensors that continuously measure constituents in the environment by absorbance or fluorescence properties (Figure 1) have had a long history of use in oceanography for measuring highly resolved concentrations and fluxes of organic matter, nutrients, and algal material. However, much of the work using commercially-available optical sensors in rivers and streams has taken place in only the last few years. Figure 1. [NOT SHOWN] Optical sensor technology is now sufficiently developed to warrant broader application for research and monitoring in coastal and freshwater systems, and the United States Geological Survey (a U.S. science agency) is now using these sensors in a variety of research and monitoring programs to better understand water quality in-situ and in real-time. Examples are numerous and range from the applications of nitrate sensors for calculating loads to estuaries susceptible to hypoxia (Pellerin et al., 2014) to the use of fluorometers to estimate methymercury fluxes (Bergamaschi et al., 2011) and disinfection byproduct formation (Carpenter et al., 2013). Transmitting these data in real-time provides information that can be used for early trend detection, help identify monitoring gaps critical for water management, and provide science-based decision support across a range of issues related to water quality, freshwater ecosystems, and human health. Despite the value of these sensors, collecting data that meet high-quality standards requires investment in and adherence to tested and established methods and protocols for sensor operation and data management (Pellerin et al., 2013). For example, optical sensor measurements can be strongly influenced by a variety of matrix effects, including water temperature, inner filtering from highly colored water, and scattering of light by suspended particles (Downing et al., 2012). Characterizing and correcting sensors for these effects – as well as the continued development of common methodologies and protocols for sensor use – will be critical to ensuring comparable measurements across sites and over time. In addition, collaborative efforts such as the Nutrient Sensor Challenge (www.nutrients-challenge.org) will continue to accelerate the development, production and use of affordable, reliable and accurate sensors for a range of environments. REFERENCES Bergamaschi .B.A., Fleck J.A., Downing B.D., Boss E., Pellerin B.A., Ganju N.K., Schoellhamer D.H., Byington A.A., Heim W.A., Stephenson M., Fujii R. (2011), Methyl mercury dynamics in a tidal wetland quantified using in situ optical measurements. Limnology and Oceanography, 56(4): 1355-1371. Carpenter K.D., Kraus T.E.C., Goldman J.H., Saraceno J., Downing B.D., Bergamaschi B.A., McGhee G., Triplett T. (2013), Sources and Characteristics of Organic Matter in the Clackamas River, Oregon, Related to the Formation of Disinfection By-products in Treated Drinking Water: U.S. Geological Survey Scientific Investigations Report 2013–5001, 78 p. Downing .B.D., Pellerin B.A., Bergamaschi B.A., Saraceno J., Kraus T.E.K. (2012), Seeing the light: The effects of particles, temperature and inner filtering on in situ CDOM fluorescence in rivers and streams. Limnology and Oceanography: Methods, 10: 767-775. Pellerin B.A., Bergamaschi B.A., Downing B.D., Saraceno J., Garrett J.D., Olsen L.D. (2013), Optical Techniques for the Determination of Nitrate in En

Conference Paper↗