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At least 379 records · Page 21Linked to original sources
USGS2025

Contrasting magnitude and timing of pulsed aqueous methylmercury bioaccumulation across a reservoir food web

Water column hypoxia is a key process influencing methylmercury (MeHg) production and availability in waterbodies worldwide. During seasonal destratification, large, short-lived pulses of aqueous MeHg may be released into the subsequently mixed water column, but little is known about the fate of these pulses, particularly whether there are concomitant increases in MeHg uptake into aquatic food webs. We examined the magnitude and timing of MeHg uptake across several trophic guilds relative to the reservoir stratification status using biweekly mercury data from water, zooplankton, and fish (Bluegill, Lepomis macrochirus and Smallmouth Bass, Micropterus dolomieu ). Zooplankton MeHg concentrations increased by up to 250% during destratification, concurrent with increases in aqueous MeHg concentrations. Zooplankton and filter-passing MeHg concentrations were positively correlated when the reservoir was mixed ( R 2 = 0.95) and destratifying ( R 2 = 0.57) but not while the reservoir was stratified ( R 2 = 0.21). Mercury concentrations in adult bluegill and juveniles of both fish species increased 20–70% following destratification, with responses lagging 4–8 weeks behind those in water and zooplankton MeHg. Mercury concentrations in piscivorous adult bass varied little over the course of the study. Our findings demonstrate the responsiveness of reservoir food webs to pulses in MeHg availability, suggesting that these pulses could play an important role in biotic MeHg exposure within and downstream of reservoirs.

Idaho, Oregon↗
USGS2006

Widespread presence of naturally occurring perchlorate in high plains of Texas and New Mexico

Perchlorate (ClO4-) occurrence in groundwater has previously been linked to industrial releases and the historic use of Chilean nitrate fertilizers. However, recently a number of occurrences have been identified for which there is no obvious anthropogenic source. Groundwater from an area of 155 000 km2 in 56 counties in northwest Texas and eastern New Mexico is impacted by the presence of ClO4-. Concentrations were generally low (<4 ppb), although some areas are impacted by concentrations up to 200 ppb. ClO4- distribution is not related to well type (public water system, domestic, agricultural, or water-table monitoring) or aquifer (Ogallala, Edward Trinity High Plains, Edwards Trinity Plateau, Seymour, or Cenozoic). Results from vertically nested wells strongly indicate a surface source. The source of ClO4- appears to most likely be atmospheric deposition. Evidence supporting this hypothesis primarily relates to the presence of ClO 4- in tritium-free older water, the lack of relation between land use and concentration distribution, the inability of potential anthropogenic sources to account for the estimated mass of ClO4-, and the positive relationship between conserved anions (e.g., IO3-, Cl-, SO4-2) and ClO4-. The ClO4- distribution appears to be mainly related to evaporative concentration and unsaturated transport. This process has led to higher ClO4- and other ion concentrations in groundwater where the water table is relatively shallow, and in areas with lower saturated thickness. Irrigation may have accelerated this process in some areas by increasing the transport of accumulated salts and by increasing the number of evaporative cycles. Results from this study highlight the potential for ClO4- to impact groundwater in arid and semiarid areas through long-term atmospheric deposition. ?? 2006 American Chemical Society.

Environmental Science & Technology↗
USGS2013

Vulnerability of streams to legacy nitrate sources

The influence of hydrogeologic setting on the susceptibility of streams to legacy nitrate was examined at seven study sites having a wide range of base flow index (BFI) values. BFI is the ratio of base flow to total streamflow volume. The portion of annual stream nitrate loads from base flow was strongly correlated with BFI. Furthermore, dissolved oxygen concentrations in streambed pore water were significantly higher in high BFI watersheds than in low BFI watersheds suggesting that geochemical conditions favor nitrate transport through the bed when BFI is high. Results from a groundwater-surface water interaction study at a high BFI watershed indicate that decades old nitrate-laden water is discharging to this stream. These findings indicate that high nitrate levels in this stream may be sustained for decades to come regardless of current practices. It is hypothesized that a first approximation of stream vulnerability to legacy nutrients may be made by geospatial analysis of watersheds with high nitrogen inputs and a strong connection to groundwater (e.g., high BFI).

Indiana;Maryl;Nebraska;North Carolina;Washington;W↗
USGS1971

Program design for San Francisco Bay Region environment and resources planning study

The "Program Design" for the San Francisco Bay Region Environment and Resources Planning Study represents a refinement, elaboration, and extension of the plans which formed the basis for the cooperative program between the Department of the Interior, Geological Survey, and the Department of Housing and Urban Development, Office of Research and Technology, formally recognized in the Letter of Agreement of October 24, 1969, and begun January 1, 1970. From the first, the study was recognized as an experimental pilot study, and new developments in the state-of-the-art in the earth sciences and in urban and regional planning were recognized as necessary. Indeed, the development of a suitable structure for such a program was considered one of the important parts of the experiment. Consequently, one of the stated goals of the Letter of Agreement was to produce a Program Design.

California↗
USGS2023

Characterizing the movement of per- and polyfluoroalkyl substances in an avian aquatic–terrestrial food web

The movement of per- and polyfluoroalkyl substances (PFAS) through linked aquatic–terrestrial food webs is not well understood. Tree swallows ( Tachycineta bicolor ) in such systems may be exposed to PFAS from multiple abiotic and/or biotic compartments. We show from fatty acid signatures and carbon stable isotopes that tree swallow nestlings in southwestern Ontario fed on both terrestrial and aquatic macroinvertebrates. The PFAS profiles of air, terrestrial invertebrates, and swallows were dominated by perfluorooctanesulfonic acid (PFOS). Short-chain perfluoroalkyl acids (PFAAs) were largely restricted to air, surface water, and sediment, and long-chain PFAAs were mainly found in aquatic invertebrates and tree swallows. PFOS, multiple long-chain perfluorocarboxylic acids [perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluorotridecanoic acid (PFTrDA)] and perfluorooctane sulfonamide precursors were estimated to bioaccumulate from air to tree swallows. PFOS bioaccumulated from air to terrestrial invertebrates, and PFOS, PFDA, and perfluorooctane sulfonamidoacetic acids (FOSAAs) bioaccumulated from water to aquatic invertebrates. PFOS showed biomagnification from both terrestrial and aquatic invertebrates to tree swallows, and PFDA and FOSAAs were also biomagnified from aquatic invertebrates to tree swallows. The movement of PFAS through aquatic–terrestrial food webs appears congener- and compartment-specific, challenging the understanding of PFAS exposure routes for multiple species involved in these food webs.

Environmental Science and Technology↗
USGS2002

TBA biodegradation in surface-water sediments under aerobic and anaerobic conditions

The potential for [U-14C] TBA biodegradation was examined in laboratory microcosms under a range of terminal electron accepting conditions. TBA mineralization to CO2 was substantial in surface-water sediments under oxic, denitrifying, or Mn(IV)-reducing conditions and statistically significant but low under SO4-reducing conditions. Thus, anaerobic TBA biodegradation may be a significant natural attenuation mechanism for TBA in the environment, and stimulation of in situ TBA bioremediation by addition of suitable terminal electron acceptors may be feasible. No degradation of [U-14C] TBA was observed under methanogenic or Fe(III)-reducing conditions.

Environmental Science & Technology↗
USGS2004

Comparison of seven protocols to identify fecal contamination sources using Escherichia coli

Microbial source tracking (MST) uses various approaches to classify fecal-indicator microorganisms to source hosts. Reproducibility, accuracy, and robustness of seven phenotypic and genotypic MST protocols were evaluated by use of Escherichia coli from an eight-host library of known-source isolates and a separate, blinded challenge library. In reproducibility tests, measuring each protocol's ability to reclassify blinded replicates, only one (pulsed-field gel electrophoresis; PFGE) correctly classified all test replicates to host species; three protocols classified 48-62% correctly, and the remaining three classified fewer than 25% correctly. In accuracy tests, measuring each protocol's ability to correctly classify new isolates, ribotyping with EcoRI and PvuII approached 100% correct classification but only 6% of isolates were classified; four of the other six protocols (antibiotic resistance analysis, PFGE, and two repetitive-element PCR protocols) achieved better than random accuracy rates when 30-100% of challenge isolates were classified. In robustness tests, measuring each protocol's ability to recognize isolates from nonlibrary hosts, three protocols correctly classified 33-100% of isolates as "unknown origin," whereas four protocols classified all isolates to a source category. A relevance test, summarizing interpretations for a hypothetical water sample containing 30 challenge isolates, indicated that false-positive classifications would hinder interpretations for most protocols. Study results indicate that more representation in known-source libraries and better classification accuracy would be needed before field application. Thorough reliability assessment of classification results is crucial before and during application of MST protocols.

Environmental Science & Technology↗
USGS2018

Linking the agricultural landscape of the Midwest to stream health with structural equation modeling

Multiple physical and chemical stressors can simultaneously affect the biological condition of streams. To better understand the complex interactions of land-use practices, water quality, and ecological integrity of streams, the U.S. Geological Survey National Water Quality Assessment Project is conducting regional-scale assessments of stream condition across the United States. In the summer of 2013, weekly water samples were collected from 100 streams in the Midwestern United States. Employing watershed theory, we used structural equation modeling (SEM) to represent a general hypothesis for how 16 variables (previously identified to be important to stream condition) might be inter-related. Again, using SEM, we evaluated the ability of this “stressor network” to explain variations in multimetrics of algal, invertebrate, and fish community health, trimming away any environmental variables not contributing to an explanation of the ecological responses. Seven environmental variables—agricultural and urban land use, sand content of soils, basin area, percent riparian area as forest, channel erosion, and relative bed stability—were found to be important for all three-community metrics. The algal and invertebrate models included water-chemistry variables not included in the fish model. Results suggest that ecological integrity of Midwest streams are affected by both agricultural and urban land uses and by the natural geologic setting, as indicated by the sand content of soils. Chemicals related to crops (pesticides and nutrients) and residential uses (pyrethroids) were found to be more strongly related to ecological integrity than were natural factors (riparian forest, watershed soil character).

Environmental Science & Technology↗
USGS2020

Mercury export from Arctic great rivers

Land–ocean linkages are strong across the circumpolar north, where the Arctic Ocean accounts for 1% of the global ocean volume and receives more than 10% of the global river discharge. Yet estimates of Arctic riverine mercury (Hg) export constrained from direct Hg measurements remain sparse. Here, we report results from a coordinated, year-round sampling program that focused on the six major Arctic rivers to establish a contemporary (2012–2017) benchmark of riverine Hg export. We determine that the six major Arctic rivers exported an average of 20 000 kg y –1 of total Hg (THg, all forms of Hg). Upscaled to the pan-Arctic, we estimate THg flux of 37 000 kg y –1 . More than 90% of THg flux occurred during peak river discharge in spring and summer. Normalizing fluxes to watershed area (yield) reveals higher THg yields in regions where greater denudation likely enhances Hg mobilization. River discharge, suspended sediment, and dissolved organic carbon predicted THg concentration with moderate fidelity, while suspended sediment and water yields predicted THg yield with high fidelity. These findings establish a benchmark in the face of rapid Arctic warming and an intensifying hydrologic cycle, which will likely accelerate Hg cycling in tandem with changing inputs from thawing permafrost and industrial activity.

Environmental Science & Technology↗
USGS2003

Scale-dependent temporal variations in stream water geochemistry

A year-long study of four western Montana streams (two impacted by mining and two “pristine”) evaluated surface water geochemical dynamics on various time scales (monthly, daily, and bi-hourly). Monthly changes were dominated by snowmelt and precipitation dynamics. On the daily scale, post-rain surges in some solute and particulate concentra tions were similar to those of early spring runoff flushing characteristics on the monthly scale. On the bi-hourly scale, we observed diel (diurnal−nocturnal) cycling for pH, dissolved oxygen, water temperature, dissolved inorganic carbon, total suspended sediment, and some total recoverable metals at some or all sites. A comparison of the cumulative geochemical variability within each of the temporal groups reveals that for many water quality parameters there were large overlaps of concentration ranges among groups. We found that short-term (daily and bi-hourly) variations of some geochemical parameters covered large proportions of the variations found on a much longer term (monthly) time scale. These results show the importance of nesting short-term studies within long-term geochemical study designs to separate signals of environmental change from natural variability.

Montana↗
USGS2010

Agricultural wetlands as potential hotspots for mercury bioaccumulation: Experimental evidence using caged fish

Wetlands provide numerous ecosystem services, but also can be sources of methylmercury (MeHg) production and export. Rice agricultural wetlands in particular may be important sites for MeHg bioaccumulation due to their worldwide ubiquity, periodic flooding schedules, and high use by wildlife. We assessed MeHg bioaccumulation within agricultural and perennial wetlands common to California’s Central Valley during summer, when the majority of wetland habitats are shallowly flooded rice fields. We introduced caged western mosquitofish ( Gambusia affinis ) within white rice ( Oryza sativa ), wild rice ( Zizania palustris ), and permanent wetlands at water inlets, centers, and outlets. Total mercury (THg) concentrations and body burdens in caged mosquitofish increased rapidly, exceeding baseline values at introduction by 135% to 1197% and 29% to 1566% among sites, respectively, after only 60 days. Mercury bioaccumulation in caged mosquitofish was greater in rice fields than in permanent wetlands, with THg concentrations at wetland outlets increasing by 12.1, 5.8, and 2.9 times over initial concentrations in white rice, wild rice, and permanent wetlands, respectively. In fact, mosquitofish caged at white rice outlets accumulated 721 ng Hg/fish in just 60 days. Mercury in wild mosquitofish and Mississippi silversides ( Menidia audens ) concurrently sampled at wetland outlets also were greater in white rice and wild rice than permanent wetlands. Within wetlands, THg concentrations and body burdens of both caged and wild fish increased from water inlets to outlets in white rice fields, and tended to not vary among sites in permanent wetlands. Fish THg concentrations in agricultural wetlands were high, exceeding 0.2 μg/g ww in 82% of caged fish and 59% of wild fish. Our results indicate that shallowly flooded rice fields are potential hotspots for MeHg bioaccumulation and, due to their global prevalence, suggest that agricultural wetlands may be important contributors to MeHg contamination.

California↗
USGS2021

A characterization of deep-sea coral and sponge communities along the California and Oregon coast using a remotely operated vehicle on the EXPRESS 2018 expedition

Deep-sea coral and sponge (DSCS) communities serve as essential fish habitats (EFH) by providing shelter and nursery habitat, increasing diversity, and increasing prey availability (Freese and Wing, 2003; Bright, 2007; Baillon et al., 2012; Henderson et al., 2020). Threats to these long-lived, fragile organisms from bottom contact fishing gear, potential offshore renewable energy development, and ocean warming and acidification have increased the need for DSCS research along the U.S. West Coast (Gomez et al., 2018; Salgado et al., 2018; Yoklavich, et al., 2018; Gugliotti et al., 2019). The focus of these studies has varied from species distribution and abundance (Yoklavich and Love, 2005; Tissot et al., 2006) to developing and validating predictive distribution models (Huff et al., 2013; Rooper et al., 2017; Kreidler, 2020) to finding medicinal uses for corals and sponges (Essack et al., 2011; Shrestha et al., 2018). Due to the vast area of unexplored seafloor within the U.S. exclusive economic zone (EEZ; 200 nautical miles off the coast) and the technological requirements and expanse of deep-sea research, there is still much to learn about the distributions and biology of DSCS. This information is critical to resource managers for effective conservation and management of DSCS habitats. Protections are provided by the Pacific Fishery Management Council (PFMC) designation of groundfish EFH conservation areas (EFHCA) and the National Marine Sanctuaries Act (NMSA). Areas designated as EFHCA are closed to bottom trawl fishing to protect and preserve seafloor habitats. Recently the PFMC adopted Amendment 28 to the Groundfish Fishery Management Plan (GFMP; Pacific Fishery Management Council, 2019) which modified EFHCAs by closing new areas identified as vulnerable and reopening areas deemed not vulnerable. The NMSA prohibits bottom disturbance from certain activities within areas designated as national marine sanctuaries, such as oil and gas exploration or extraction, cable laying, and other forms of seabed alteration or construction that disturb benthic communities. NOAA’s Deep-Sea Coral and Research Technology Program (DSCRTP) began a 4-yr funding initiative for the U.S. West Coast in 2017. The goals of the West Coast Deep-Sea Coral Initiative (WCDSCI) were to: 1) gather baseline information on areas subject to fishing regulation changes prior to the implementation of Amendment 28; 2) improve our understanding of known DSCS bycatch “hot spots”; and 3) explore and assess DSCS resources within NOAA National Marine Sanctuaries with emphasis on areas of sanctuary resource protection and management concerns. During the first year of the program, a research cruise was developed to survey the West Coast from Oregon to California studying the DSCS ecosystems in priority areas. The 31-day expedition (9 Oct – 8 Nov, 2018) was launched from the NOAA Ship Bell M. Shimada, beginning in Newport, OR and ending in San Diego, CA. The science team assembled for this cruise were members of the EXpanding Pacific Research and Exploration of Submerged Systems (EXPRESS) campaign, which brings together researchers from federal and nonfederal institutions to collaborate on scientific expeditions targeting the deepwater areas off California, Oregon, and Washington. EXPRESS supports researchers leveraging funding, resources, personnel, and expertise to accomplish more science than would have been possible by a single entity alone. The 2018 coastwide expedition included research partners from National Marine Fisheries Service (NMFS) Southwest Fisheries Science Center (SWFSC) and Northwest Fisheries Science Center (NWFSC), National Ocean Service (Channel Islands, Cordell Bank, Greater Farallones, and Monterey Bay National Marine Sanctuaries), Bureau of Ocean Energy Management (BOEM), U.S. Geological Survey (USGS), and Monterey Bay Aquarium Research Institute (MBARI). Research objectives for the cruise were to: 1) Collect DSCS baseline information at 10 of the EFHCA sites undergoing protection modifications by the Pacific Fishery Management Council. 2) Collect DSCS and fish data at previously unexplored sites within West Coast National Marine Sanctuaries. 3) Revisit a subset of previously surveyed sites to document if changes in DCSC have occurred over time. 4) Collect information to validate BOEM supported cross-shelf habitat suitability models for DSCS. 5) Collect samples to help in identifying (and understanding) West Coast DSCS and expand use of new technologies (ROV, AUV, and environmental DNA [eDNA]). 6) Collect water samples for coastwide eDNA, nutrient, and carbon chemistry studies.

California, Oregon↗
USGS2016

U.S. Geological Survey science for the Wyoming Landscape Conservation Initiative—2015 annual report

This is the eighth annual report highlighting U.S. Geological Survey (USGS) science and decision-support activities conducted for the Wyoming Landscape Conservation Initiative (WLCI). The activities address specific management needs identified by WLCI partner agencies. In 2015, USGS scientists continued 24 WLCI projects in 5 categories: (1) acquiring and analyzing resource-condition data to form a foundation for understanding and monitoring landscape conditions and projecting changes; (2) using new technologies to improve the scope and accuracy of landscape-scale monitoring and assessments, and applying them to monitor indicators of ecosystem conditions and the effectiveness of on-the-ground habitat projects; (3) conducting research to elucidate the mechanisms that drive wildlife and habitat responses to changing land uses; (4) managing and making accessible the large number of databases, maps, and other products being developed; and (5) coordinating efforts among WLCI partners, helping them to use USGS-developed decision-support tools, and integrating WLCI outcomes with future habitat enhancement and research projects. Of the 24 projects, 21 were ongoing, including those that entered new phases or more in-depth lines of inquiry, 2 were new, and 1 was completed. A highlight of 2015 was the WLCI science conference sponsored by the USGS, Bureau of Land Management, and National Park Service in coordination with the Wyoming chapter of The Wildlife Society. Of 260 participants, 41 were USGS professionals representing 13 USGS science centers, field offices, and Cooperative Wildlife Research Units. Major themes of USGS presentations included using new technologies for developing more efficient research protocols for modeling and monitoring natural resources, researching effects of energy development and other land uses on wildlife species and habitats of concern, and modeling species distributions, population trends, habitat use, and effects of land-use changes. There was also a special session on the effectiveness of Wyoming’s Sage-Grouse Executive Order. Combined, USGS presentations provided WLCI partners with a wealth of information and conservation tools. The project completed in 2015 yielded an index of important agricultural lands in the WLCI region. The index improves upon existing measures of agricultural productivity and provides planners and managers with additional values to consider when making decisions about land use and conservation actions. The two new projects include an analysis of satellite imagery to quantify sagebrush productivity and mortality, and an evaluation of how groundwater and small streams interact in the upper Green River Basin. Initiated in response to concern among WLCI partners that large areas of sagebrush appear to have died recently, the sagebrush study objectives are to assess effects of these mortality events on overall sagebrush ecosystem productivity, evaluate the feasibility of using satellite imagery to detect patterns in sagebrush mortality over time, and identify factors driving these mortality events. The groundwater-streamflow interaction study is being conducted by hydrologists and fish ecologists to better understand how groundwater-streamflow interactions are affected by energy-resource development and how native fish communities are affected by these factors. Expected outcomes of both new projects will provide WLCI partners with additional information and decision-support tools. Highlights of ongoing science foundation activities included simulations of nine alternative build-out scenarios for oil and gas development and an associated online fact sheet that explains how the simulations were conducted, with an applied example for the Atlantic Rim. Also completed in 2015 was an update of the USGS online inventory of mineral resources data, and publication of a USGS uranium resource survey for the WLCI region. Combined, the outcomes of this work provide decisionmakers and managers with important baseline information for existing and (or) future planning and monitoring efforts. Terrestrial monitoring activities in 2015 emphasized the use of satellite data in combination with other technologies and field data to monitor, assess, and (or) forecast distribution patterns and (or) trends in sagebrush ecosystems, seasonal and migration stopover habitats used by mule deer and elk, and semi-arid aspen woodlands. Several professional papers detailing new monitoring models and results have been published. Combined, this and related work will help managers understand distribution patterns and trends among priority habitats, identify areas in need of restoration or conservation, and monitor the effectiveness of habitat-management actions. Aquatic monitoring activities entailed not only the new groundwater-streamflow interaction study already mentioned, but also continued monitoring with streamgages paired with nearby wells in the Green River Basin to assess groundwater effects on streamflow and surface water temperatures. A map that portrays groundwater levels and general direction of flow in the Green River Basin was published as well . Overall, outcomes of USGS hydrological research and monitoring will inform WLCI partners about water resources in the WLCI region and help to explain fish-community responses to energy-resource development. In 2015, USGS terrestrial wildlife ecologists continued to make crucial strides towards better understanding wildlife species responses to energy-resource development and other land-use changes. This body of research includes six taxa that require or heavily depend on sagebrush habitats: sage-grouse, pygmy rabbits, 3 songbird species, and mule deer. Native fish communities are also being evaluated. Approaches include modeling and mapping wildlife species distributions, abundances, and trends; using satellite and other technologies to track wildlife seasonal movements; conducting successive phases of research that build on the knowledge gained through prior phases to reveal the specific factors or thresholds that drive population- or individual-level responses to changes; and conducting population viability analyses. Additionally, wildlife habitat association models for pygmy rabbit and sage-grouse were combined with the oil and gas build-out scenarios to project species responses to alternative energy development scenarios. Outcomes of the wildlife response research are helping decisionmakers and managers identify specific factors that contribute to species population trends, the potential for spatial overlap between important wildlife habitats and proposed energy-resource development, locations of priority habitats for restoration and conservation, and more. Data and WLCI Web site management highlights of 2015 included not only ongoing software upgrades, but also an update of the datasets displayed in two of the online products developed for the WLCI effort: (1) a map of 15,532 oil and natural gas well pad scars and other features associated with oil and gas extraction, and (2) a map of oil and gas, oil shale, uranium, and solar energy production, both for southwestern Wyoming. In addition, a map viewer was developed for a previously published map of coal and wind production in relation to sage-grouse distribution and core management areas in southwestern Wyoming. Combined, these maps place valuable decision-support tools in the hands of WLCI partners. The USGS coordination efforts on behalf of the WLCI in 2015 included significant work on planning and executing the WLCI science conference. They also included ongoing efforts to support Local Project Development Teams and the WLCI Coordination Team (CT) with developing conservation priorities and strategies, identifying priority areas for future conservation actions, supporting the evaluation and ranking of conservation projects, and evaluating the ways in which proposed habitat projects relate to WLCI priorities. In 2015, the USGS also assisted the WLCI CT with updating the WLCI Conservation Action Plan.

Wyoming↗
USGS2010

Partition coefficients of organic contaminants with carbohydrates

In view of the current lack of reliable partition coefficients for organic compounds with carbohydrates ( K ch ), carefully measured values with cellulose and starch, the two major forms of carbohydrates, are provided for a wide range of compounds: short-chain chlorinated hydrocarbons, halogenated benzenes, alkyl benzenes, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls, and organochlorine pesticides. To ensure the accuracy of the K ch data, solute concentrations in both water and carbohydrate phases are measured by direct solvent extraction of the samples. For a given compound, the observed partition coefficient with cellulose ( K cl ) is virtually the same as that with starch ( K st ). This finding expedites the evaluation of organic contamination with different forms of carbohydrates. The presently determined K ch values of 13 PAHs are substantially lower (by 3−66 times) than the literature data; the latter are suspect as they were obtained with (i) presumably impure carbohydrate samples or (ii) indirectly measured equilibrium solute concentrations in carbohydrate and water phases. Although the K ch values are generally considerably lower than the respective K ow (octanol−water) or K lipid (lipid−water), accurate K ch data are duly required to accurately estimate the contamination of carbohydrates by organic compounds because of the abundance of carbohydrates over lipids in crops and plants. To overcome the current lack of reliable K ch data for organic compounds, a close correlation of log K ch with log K ow has been established for predicting the unavailable K ch data for low-polarity compounds.

Environmental Science and Technology↗
USGS2010

Tet and sul antibiotic resistance genes in livestock lagoons of various operation type, configuration, and antibiotic occurrence

Although livestock operations are known to harbor elevated levels of antibiotic resistant bacteria, few studies have examined the potential of livestock waste lagoons to reduce antibiotic resistance genes (ARGs). The purpose of this study was to determine the prevalence and examine the behavior of tetracycline [tet(O) and tet(W)] and sulfonamide [sul(I) and su/(II)] ARGsin a broad cross-section of livestock lagoons within the same semiarid western watershed. ARGs were monitored for one year in the water and the settled solids of eight lagoon systems by quantitative polymerase chain reaction. In addition, antibiotic residues and various bulk water quality constituents were analyzed. It was found that the lagoons of the chicken layer operation had the lowest concentrations of both tet and sul ARGs and low total antibiotic concentrations, whereas su ARGs were highest in the swine lagoons, which generally corresponded to the highest total antibiotic concentrations. A marginal benefit of organic and small dairy operations also was observed compared to conventional and large dairies, respectively. In all lagoons, su ARGs were observed to be generally more recalcitrant than tet ARGs. Also, positive correlations of various bulk water quality constituents were identified with tet ARGs but not sul ARGs. Significant positive correlations were identified between several metals and tet ARGs, but Pearson's correlation coefficients were mostly lower than those determined between antibiotic residues and ARGs. This study represents a quantitative characterization of ARGs in lagoons across a variety of livestock operations and provides insight into potential options for managing antibiotic resistance emanating from agricultural activities.

Environmental Science & Technology↗
USGS2019

Enabling real-time user interaction for decision support: Experiences extending a local agave platform metadata service

The University of Hawai'i Information Technology Services Cyber-infrastructure team in partnership with the United States Geological Survey developed the Hawai'i groundwater recharge tool, a decision support tool, as part of the 'Ike Wai Gateway to support water sustainability research for the state of Hawai'i. To enable the development of the tool within the existing University of Hawai'i Agave platform that the 'Ike Wai Gateway is built on, the Metadata application programmatic interface (API) and Agave infrastructure needed to be extended to store and retrieve spatial data and handle a larger number of requests. The development team successfully added the functionality to the local University of Hawai'i Agave platform instance to support the storage of deserialized vector data and metadata that can be spatially queried across hundreds of thousands of records to enable decision support applications within a science gateway.

Hawaii↗
USGS2023

Linking meso-scale spatial variation in methylmercury production to bioaccumulation in tidal marsh food webs

Differences in sediment biogeochemistry among tidal marsh features with different hydrological and geomorphological characteristics, including marsh interiors, marsh edges, first-order channels, and third-order channels, can result in spatial variation in MeHg production and availability. To better understand the link between MeHg production in sediments and bioaccumulation in primary and secondary consumer invertebrates and fish, we characterized mesoscale spatial variation in sediment biogeochemistry and MeHg concentrations of sediments, water, and consumer tissues among marsh features. Our results indicated that marsh interiors had biogeochemical conditions, including greater concentrations of organic matter and sulfate reduction rates, that resulted in greater MeHg concentrations in sediments and surface water particulates from marsh interiors compared to other features. Tissue MeHg concentrations of consumers also differed among features, with greater concentrations from marsh edges and interiors compared to channels. This spatial mismatch of MeHg concentrations in sediments and water compared to those in consumers may have resulted from differences in behavior and physiology among consumers that influenced the spatial scale over which MeHg was integrated into tissues. Our results highlight the importance of sampling across a suite of marsh features and considering the behavioral and physiological traits of sentinel taxa for contaminant monitoring studies.

Environmental Science and Technology↗
USGS2011

Interlaboratory comparison of real-time pcr protocols for quantification of general fecal indicator bacteria

The application of quantitative real-time PCR (qPCR) technologies for the rapid identification of fecal bacteria in environmental waters is being considered for use as a national water quality metric in the United States. The transition from research tool to a standardized protocol requires information on the reproducibility and sources of variation associated with qPCR methodology across laboratories. This study examines interlaboratory variability in the measurement of enterococci and Bacteroidales concentrations from standardized, spiked, and environmental sources of DNA using the Entero1a and GenBac3 qPCR methods, respectively. Comparisons are based on data generated from eight different research facilities. Special attention was placed on the influence of the DNA isolation step and effect of simplex and multiplex amplification approaches on interlaboratory variability. Results suggest that a crude lysate is sufficient for DNA isolation unless environmental samples contain substances that can inhibit qPCR amplification. No appreciable difference was observed between simplex and multiplex amplification approaches. Overall, interlaboratory variability levels remained low (<10% coefficient of variation) regardless of qPCR protocol.

Environmental Science & Technology↗