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At least 343 records · Page 19Linked to original sources
USGS2020

Differences in neonicotinoid and metabolite sorption to activated carbon are driven by alterations to the insecticidal pharmacophore

Widespread application of neonicotinoids has led to their proliferation in waters. Despite low neonicotinoid hydrophobicity, our prior studies implicated granular activated carbon (GAC) in neonicotinoid removal. Based on known receptor binding characteristics, we hypothesized that the insecticidal pharmacophore influences neonicotinoid sorption. Our objectives were to illuminate drivers of neonicotinoid sorption for parent neonicotinoids (imidacloprid, clothianidin, thiamethoxam, and thiacloprid) and pharmacophore-altered metabolites (desnitro-imidacloprid and imidacloprid urea) to GAC, powdered activated carbon, and carbon nanotubes (CNTs). Neonicotinoid sorption to GAC was extensive and largely irreversible, with significantly greater sorption of imidacloprid than desnitro-imidacloprid. Imidacloprid and imidacloprid urea (electronegative pharmacophores) sorbed most extensively to nonfunctionalized CNTs, whereas desnitro-imidacloprid (positive pharmacophore) sorbed most to COOH-CNTs, indicating the importance of charge interactions and/or hydrogen bonding between the pharmacophore and carbon surface. Water chemistry parameters (temperature, alkalinity, ionic strength, and humic acid) inhibited overall neonicotinoid sorption, suggesting that pharmacophore-driven sorption in real waters may be diminished. Analysis of a full-scale drinking water treatment plant GAC filter influent, effluent, and spent GAC attributes neonicotinoid/metabolite removal to GAC under real-world conditions for the first time. Our results demonstrate that the neonicotinoid pharmacophore not only confers insecticide selectivity but also impacts sorption behavior, leading to less effective removal of metabolites by GAC filters in water treatment.

Environmental Science and Technology↗
USGS1991

Geochemical mass-balance in a small forested watershed in southwestern Pennsylvania

An intensive hydrologic investigation of the North Fork Bens Creek Watershed on Laurel Hill in southwestern Pennsylvania was made during 1984-85. Precipitation was sampled weekly, and stream water was sampled monthly and during selected storms for discharge and chemical composition. The watershed is underlain by sandstone and sandy shale consisting of quartz, feldspar, muscovite, chlorite, calcite, and kaolinite. Watershed chemical flux for the sum of Ca++, Mg++, Na+, and K+ shows that solutes from wet deposition account for 19 to 21 percent of the load in runoff from the watershed. Cation exchange and weathering account for the net changes in the chemistry of streamflow. Alteration of orthoclase, muscovite, chlorite, and albite to kaolinite accounts for 36 percent of the neutralization of H+ resulting from precipitation input and carbonic-acid weathering. Dissolution of calcite accounts for 34 percent of H+ neutralization. Dissolution of aluminum-bearing minerals in the soil matrix accounts for 25 percent of H+ neutralization.

Conference Paper↗
USGS2006

Description, Properties, and Degradation of Selected Volatile Organic Compounds Detected in Ground Water--A Review of Selected Literature

This report provides abridged information describing the most salient properties and biodegradation of 27 chlorinated volatile organic compounds detected during ground-water studies in the United States. This information is condensed from an extensive list of reports, papers, and literature published by the U.S. Government, various State governments, and peer-reviewed journals. The list includes literature reviews, compilations, and summaries describing volatile organic compounds in ground water. This report cross-references common names and synonyms associated with volatile organic compounds with the naming conventions supported by the International Union of Pure and Applied Chemistry. In addition, the report describes basic physical characteristics of those compounds such as Henry's Law constant, water solubility, density, octanol-water partition (log Kow), and organic carbon partition (log Koc) coefficients. Descriptions and illustrations are provided for natural and laboratory biodegradation rates, chemical by-products, and degradation pathways.

Open-File Report↗
USGS2013

Factors related to occurrence and distribution of selected bacterial and protozoan pathogens in Pennsylvania streams

The occurrence and distribution of fecal indicator bacteria (FIB) and bacterial and protozoan pathogens are controlled by diverse factors. To investigate these factors in Pennsylvania streams, 217 samples were collected quarterly from a 27-station water-quality monitoring network from July 2007 through August 2009. Samples were analyzed for concentrations of Escherichia coli (EC) and enterococci (ENT) indicator bacteria, concentrations of Cryptosporidium oocysts and Giardia cysts, and the presence of four genes related to pathogenic types of EC ( eae A, stx 2, stx 1, rfb O157 ) plus three microbial source tracking (MST) gene markers that are also associated with pathogenic ENT and EC ( esp , LTIIa, STII). Water samples were concurrently analyzed for basic water chemistry, physical measures of water quality, nutrients, metals, and a suite of 79 organic compounds that included hormones, pharmaceuticals, and antibiotics. For each sample location, stream discharge was measured by using standardized methods at the time of sample collection, and ancillary sample site information, such as land use and geological characteristics, was compiled. Samples exceeding recreational water quality criteria were more likely to contain all measured pathogen genes but not Cryptosporidium or Giardia (oo)cysts. FIB and Giardia density and frequency of eae A gene occurrence were significantly related to season. When discharge at a sampling location was high (>75th percentile of daily mean discharge), there were greater densities of FIB and Giardia , and the stx2 , rfb O157 , STII, and esp genes were found more frequently than at other discharge conditions. Giardia occurrence was likely related to nonpoint sources, which are highly influential during seasonal overland transport resulting from snowmelt and elevated precipitation in late winter and spring in Pennsylvania. When MST markers of human, swine, or bovine origin were present, samples more frequently carried the eae A, stx 2, stx 1, and rfb O157 genes, but no genes were related exclusively to an individual MST marker. The human source pharmaceuticals (HSPs) acetaminophen and caffeine were correlated with Giardia , and the presence of HSPs proved to be more useful than MST markers in distinguishing the occurrence of Giardia . The HSPs caffeine and carbamazepine were correlated with the sum total of pathogen genes detected in a sample, demonstrating the value of using HSPs as an indicator of fecally derived pathogens. Sites influenced by urban land use with less forest were more likely to have greater FIB and Giardia densities and sum of the array of pathogen genes. Sites dominated by shallow carbonate bedrock in the upstream catchment were likely to have greater FIB densities and higher sum totals of pathogen genes but no correlation with Giardia detection. Our study provides a range of specific environmental, chemical, geologic, and land-use variables related to occurrence and distribution of FIB and selected bacterial and protozoan pathogens in Pennsylvania streams. The information presented could be useful for resource managers in understanding bacterial and protozoan pathogen occurrence and their relation to fecal indicator bacteria in similar settings.

Pennsylvania↗
USGS2023

Reevaluation of 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalency factors for dioxin-like polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and polychlorinated biphenyls for fishes

An expert meeting was organized by the World Health Organization (WHO) in 1997 to streamline assessments of risk posed by mixtures of dioxin-like chemicals (DLCs) through development of 2,3,7,8-tetrachlorodibenzo- p -dioxin (2,3,7,8-TCDD) equivalency factors (TEFs) for mammals, birds, and fishes. No reevaluation has been performed for fish TEFs. Therefore, the objective of the present study was to reevaluate the TEFs for fishes based on an updated database of relative potencies (RePs) for DLCs. Selection criteria consistent with the WHO meeting resulted in 53 RePs across 14 species of fish ultimately being considered. Of these RePs, 70% were not available at the time of the WHO meeting. These RePs were used to develop updated TEFs for fishes based on a similar decision process as used at the WHO meeting. The updated TEF for 16 DLCs was greater than the WHO TEF, but only four differed by more than an order of magnitude. Measured concentrations of DLCs in four environmental samples were used to compare 2,3,7,8-TCDD equivalents (TEQs) calculated using the WHO TEFs relative to the updated TEFs. The TEQs for none of these environmental samples differed by more than an order of magnitude. Therefore, present knowledge supports that the WHO TEFs are suitable potency estimates for fishes. However, the updated TEFs pull from a larger database with a greater breadth of data and as a result offer greater confidence relative to the WHO TEFs. Risk assessors will have different criteria in the selection of TEFs, and the updated TEFs are not meant to immediately replace the formal WHO TEFs; but those who value a larger database and increased confidence in TEQs could consider using the updated TEFs.

Environmental Toxicology and Chemistry↗
USGS2023

Survey of chromium and selected element concentrations in rock, alluvium, and core material

Between 1952 and 1964, hexavalent chromium, Cr(VI), was released into groundwater from the Pacific Gas and Electric Company (PG&E) compressor station in Hinkley, California, in the western Mojave Desert 80 miles northeast of Los Angeles, California. In 2015, the extent of anthropogenic Cr(VI) in groundwater in Hinkley and Water Valleys was uncertain, and some Cr(VI) in groundwater may be naturally occurring from rock and aquifer material. On the basis of more than 1,500 portable (handheld) X-ray fluorescence (pXRF) measurements on more than 250 samples of rock, surficial alluvium, and core material from selected wells in Hinkley and Water Valleys, chromium concentrations are commonly low compared to the average bulk continental abundance of 185 milligrams per kilogram (mg/kg). However, chromium concentrations are as high as 530 mg/kg in mafic hornblende diorite that crops out along the western margin of Hinkley Valley in Iron Mountain. Other chromium-containing rocks in the area are either (1) not consistently high in chromium, (2) have limited areal extent, or (3) in the case of basalt, are present only in Water Valley. Chromium concentrations in core material adjacent to the screened intervals of wells sampled for water chemistry and isotopic composition as part of the U.S. Geological Survey Cr(VI) background study ranged from less than the study reporting level (SRL) of 5 mg/kg to 410 mg/kg, with a median concentration of 23 mg/kg. Chromium concentrations in core material were lower in the eastern subarea and higher in the western and the northern subareas of Hinkley Valley and in Water Valley. The highest chromium concentration in core material was in weathered hornblende diorite bedrock. Chromium concentrations in core material adjacent to the screened interval of sampled wells were log-normally distributed below a threshold of 85 mg/kg, and 3 percent of chromium concentrations were greater than 85 mg/kg. Manganese can oxidize trivalent chromium, Cr(III), to Cr(VI). Similar to chromium, manganese concentrations in core material also were log-normally distributed below a threshold of 970 mg/kg, and 5 percent of manganese concentrations were greater than 970 mg/kg. Both chromium and manganese concentrations were higher in fine-textured core material and in visually abundant iron- and manganese-oxide coatings on the surfaces of mineral grains. High concentrations of chromium and manganese in core material commonly co-occurred. Fine-textured core material, chromium concentrations greater than 85 mg/kg, and manganese concentrations greater than 970 mg/kg in core material adjacent to the screened interval of sampled wells were selected for use as metrics (threshold values) within a summative-scale analysis (SSA) developed to identify natural and anthropogenic Cr(VI) in water from wells later within this professional paper (chapter G). Principal component analysis (PCA) of 18 elements within surficial alluvium, rock, and core material measured using pXRF shows distinct elemental assemblages associated with (1) older and more recent “Mojave-type” deposits, including alluvium and lake-margin (beach) deposits sourced from the Mojave River, (2) alluvium eroded from mafic rock, including hornblende diorite that crops out on Iron Mountain, (3) alluvium eroded from felsic volcanic and hydrothermal rock that crops out on Mount General along the eastern margin of Hinkley Valley, (4) playa/mudflat and other fine-textured deposits, and (5) material with visually abundant iron- and manganese-oxide coatings. Most wells sampled as part of this study were completed in Mojave-type deposits. Portable (handheld) X-ray fluorescence data measured on core material from those wells do not appear to be different or unusual compared to the magnitude and range of data from the larger Mojave River groundwater basin, and the core material has a low-chromium, felsic composition consistent with a Mojave River origin. In general, the elemental composition of core material from wells was not measurably altered by admixtures with local mafic, felsic volcanic, or hydrothermal source materials; although, where present, admixtures with basalt may contribute chromium to core material.

California↗
USGS2006

Concentrations, loads, and yields of particle-associated contaminants in urban creeks, Austin, Texas, 1999-2004

Concentrations, loads, and yields of particle-associated (hydrophobic) contaminants (PACs) in urban runoff in creeks in Austin, Texas, were characterized using an innovative approach: large-volume suspended-sediment sampling. This approach isolates suspended sediment from the water column in quantities sufficient for direct chemical analysis of PACs. During 1999-2004, samples were collected after selected rain events from each of five stream sites and Barton Springs for a study by the U.S. Geological Survey, in cooperation with the City of Austin. Sediment isolated from composited samples was analyzed for major elements, metals, organochlorine compounds, and polycyclic aromatic hydrocarbons (PAHs). In addition, at the Shoal Creek and Boggy Creek sites, individual samples for some events were analyzed to investigate within-event variation in sediment chemistry. Organochlorine compounds detected in suspended sediment included chlordane, dieldrin, DDD, DDE, DDT, and polychlorinated biphenyls (PCBs). Concentrations of PACs varied widely both within and between sites, with higher concentrations at the more urban sites and multiple nondetections at the least-urban sites. Within-site variation for metals and PAHs was smaller than between-site variation, and concentrations and yields of these and the organochlorine compounds correlated positively to the percentage of urban land use in the watershed. Loads of most PACs tested correlated significantly with suspended-sediment loads. Concentrations of most PACs correlated strongly with three measures of urban land use. Variation in suspended-sediment chemistry during runoff events was investigated at the Shoal and Boggy Creek sites. Five of the eight metals analyzed, dieldrin, chlordane, PCBs, and PAHs were detected at the highest concentrations in the first sample collected at the Shoal Creek site, a first-flush effect, but not at the Boggy Creek site. Temporal patterns in concentrations of DDT and its breakdown products varied from one event to the next. In spite of the first-flush effect in concentrations at the Shoal Creek site, most of the contaminant load was transported at peak discharge, when suspended-sediment concentration and load are maximum.

Scientific Investigations Report↗
USGS2004

Monitoring suspended sediment and associated trace element and nutrient fluxes in large river basins in the USA

In 1996, the US Geological Survey converted its occurrence and distribution-based National Stream Quality Accounting Network (NASQAN) to a national, flux-based water-quality monitoring programme. The main objective of the revised programme is to characterize large USA river basins by measuring the fluxes of selected constituents at critical nodes in various basins. Each NASQAN site was instrumented to determine daily discharge, but water and suspended sediment samples are collected no more than 12-15 times per year. Due to the limited sampling programme, annual suspended sediment fluxes were determined from site-specific sediment rating (transport) curves. As no significant relationship could be found between either discharge or suspended sediment concentration (SSC) and suspended sediment chemistry, trace element and nutrient fluxes are estimated using site-specific mean or median chemical levels determined from a number of samples collected over a period of years, and under a variety of flow conditions.

Conference Paper↗
USGS2016

The use of amino acid indices for assessing organic matter quality and microbial abundance in deep-sea Antarctic sediments of IODP Expedition 318

The Adélie Basin, located offshore of the Wilkes Land margin, experiences unusually high sedimentation rates (~ 2 cm yr − 1 ) for the Antarctic coast. This study sought to compare depthwise changes in organic matter (OM) quantity and quality with changes in microbial biomass with depth at this high-deposition site and an offshore continental margin site. Sediments from both sites were collected during the International Ocean Drilling (IODP) Program Expedition 318. Viable microbial biomass was estimated from concentrations of bacterial-derived phospholipid fatty acids, while OM quality was assessed using four different amino acid degradation proxies. Concentrations of total hydrolysable amino acids (THAA) measured from the continental margin suggest an oligotrophic environment, with THAA concentrations representing only 2% of total organic carbon with relative proportions of non-protein amino acids β-alanine and γ-aminobutyric acid as high as 40%. In contrast, THAA concentrations from the near-shore Adélie Basin represent 40%–60% of total organic carbon. Concentrations of β-alanine and γ-aminobutyric acid were often below the detection limit and suggest that the OM of the basin as labile. DI values in surface sediments at the Adélie and margin sites were measured to be + 0.78 and − 0.76, reflecting labile and more recalcitrant OM, respectively. Greater DI values in deeper and more anoxic portions of both cores correlated positively with increased relative concentrations of phenylalanine plus tyrosine and may represent a change of redox conditions, rather than OM quality. This suggests that DI values calculated along chemical profiles should be interpreted with caution. THAA concentrations, the percentage of organic carbon (C AA %) and total nitrogen (N AA %) represented by amino acids at both sites demonstrated a significant positive correlation with bacterial abundance estimates. These data suggest that the selective degradation of amino acids, as indicated by THAA concentrations, C AA % or N AA % values may be a better proxy for describing the general changes in sedimentary bacterial abundances than total organic matter or bulk sedimentation rates.

Marine Chemistry↗
USGS2014

A 19-year record of chemical and isotopic composition of water from springs of the Shenandoah National Park, Virginia, 1995-2014

During October 1995 through March 2014, the U.S. Geological Survey in cooperation with the National Park Service, Luray, Virginia Station collected and analyzed samples of selected springs, air and unsaturated-zone gases in Shenandoah National Park, Virginia. The 19-year record of measurements of chemical and isotopic composition of water discharging from 34 springs located along the crest of the Blue Ridge Mountains in Shenandoah National Park, Virginia, is reported. These data include field measurements of water temperature, specific conductance, concentrations of dissolved oxygen (O 2 ), and pH. Laboratory measurements included major-, minor-, and trace-element chemistry; concentrations of dissolved gases (nitrogen, [N 2 ] argon [Ar], oxygen, and carbon dioxide [CO 2 ]); concentrations of dissolved trace atmospheric gases, including trichlorofluoromethane (CFC-11), dichlorodifluoromethane (CFC-12), and trichlorotrifluoroethane (CFC-113) and sulfur hexafluoride (SF 6 ); and hydrogen stable isotopic composition (δ 2 H) and oxygen isotopic composition (δ 18 O) of water. The data include an up to 14-year time series record of monthly sampling at five springs collected between 1995 and 2013. The measurements included temperature, specific conductance, pH, and discharge recorded at 30-minute intervals. Atmospheric mixing ratios of CFC-11, CFC-12, CFC-113, trifluorobromomethane (CF 3 Br), SF 6 , and trifluoromethyl sulfur pentafluoride (SF 5 CF 3 ) in air from the Big Meadows Air Monitoring Station, Shenandoah National Park, were measured at approximately weekly intervals from September 1995 through March 2014. Additional data include monthly (between May 2001 and August 2003) measurements of temperature, N 2 , O 2 , Ar, CO 2 , CFC-12, CFC-11, CFC-113, and SF 6 concentrations in unsaturated-zone air from seven multilevel piezometers in Shenandoah National Park and at the U.S. Geological Survey National Center in Reston, Virginia. All samples were analyzed at the U.S. Geological Survey Laboratories in Reston, Virginia.

Virginia↗
USGS2021

Response to Gard et al.'s (2021) Comments on the Critical Review “Polychlorinated Biphenyl Tissue-Concentration Thresholds for Survival, Growth, and Reproduction in Fish”

This response is offered to the critique by Gard et al. ( 2021 ) of our meta-analysis of polychlorinated biphenyl (PCB)-induced toxicity data in fish (Berninger and Tillitt 2019 ). Gard et al. ( 2021 ) offered numerous comments, the most substantive suggesting that 1) we should have added no-observable–adverse effect residue (NOAER) data from additional studies and all data points from selected studies, and 2) the uncertainty of aggregating data from different PCB mixtures, different species, and different life stages is too great based on a limited data set. The additional studies Gard et al. suggested either were not designed to produce toxicological data, had experimental design issues, were confounded by co-contaminants, or did not contain paired exposure–effects data and as such were not appropriate to add to the data set. Lowest-observable–adverse effect residue (LOAER) values were selected for our analysis because they represent population sensitivities from the central portions of a frequency distribution (the linear portion of dose–response curves). As a consequence, there is less uncertainty in these input data (LOAER values) and greater confidence that they accurately represent the response of fish populations tested. Modeling NOAER values is in the extrapolation portion of a dose–response relationship and subject to enhanced uncertainty. The Gard et al. ( 2021 ) critique ignores this fundamental principle of toxicology and adds/deletes data points from our data set without clear selection criteria, which artificially enhances the uncertainty of their models that ultimately are not useful. We reject the premise that it is better to use individual study data as opposed to aggregation of PCB-induced toxicity thresholds in fish.

Environmental Toxicology and Chemistry↗
USGS2011

Modeling regional coral reef responses to global warming and changes in ocean chemistry: Caribbean case study

Climatic change threatens the future of coral reefs in the Caribbean and the important ecosystem services they provide. We used a simulation model [C OMBO (“COral Mortality and Bleaching Output”)] to estimate future coral cover in the part of the eastern Caribbean impacted by a massive coral bleaching event in 2005. C OMBO calculates impacts of future climate change on coral reefs by combining impacts from long-term changes in average sea surface temperature (SST) and ocean acidification with impacts from episodic high temperature mortality (bleaching) events. We used mortality and heat dose data from the 2005 bleaching event to select historic temperature datasets, to use as a baseline for running C OMBO under different future climate scenarios and sets of assumptions. Results suggest a bleak future for coral reefs in the eastern Caribbean. For three different emissions scenarios from the Intergovernmental Panel on Climate Change (IPCC; B1, A1B, and A1FI), coral cover on most Caribbean reefs is projected to drop below 5% by the year 2035, if future mortality rates are equivalent to some of those observed in the 2005 event (50%). For a scenario where corals gain an additional 1–1.5°C of heat tolerance through a shift in the algae that live in the coral tissue, coral cover above 5% is prolonged until 2065. Additional impacts such as storms or anthropogenic damage could result in declines in coral cover even faster than those projected here. These results suggest the need to identify and preserve the locations that are likely to have a higher resiliency to bleaching to save as many remnant populations of corals as possible in the face of projected wide-spread coral loss.

Climatic Change↗
USGS2001

Concentrations and annual fluxes for selected water-quality constituents from the USGS National Stream Quality Accounting Network (NASQAN) 1996-2000

This report contains concentrations and annual mass fluxes (loadings) for a broad range of water-quality constituents measured during 1996-2000 as part of the U.S. Geological Survey National Stream Quality Accounting Network (NASQAN). During this period, NASQAN operated a network of 40-42 stations in four of the largest river basins of the USA: the Colorado, the Columbia, the Mississippi (including the Missouri and Ohio), and the Rio Grande. The report contains surface-water quality data, streamflow data, field measurements (e.g. water temperature and pH), sediment-chemistry data, and quality-assurance data; interpretive products include annual and average loads, regression parameters for models used to estimate loads, sub-basin yield maps, maps depicting percent detections for censored constituents, and diagrams depicting flow-weighted average concentrations. Where possible, a regression model relating concentration to discharge and season was used for flux estimation. The interpretive context provided by annual loads includes identifying source and sink areas for constituents and estimating the loadings to receiving waters, such as reservoirs or the ocean.

Water-Resources Investigations Report↗
USGS1998

Chemistry and isotopic composition of ground water along a section near the Newmark area, San Bernardino County, California

Chemical and isotopic analyses and flow-meter measurements in pumped wells were used to determine the source, movement, and age of ground water along a section of the valley-fill aquifer from the San Jacinto Fault to the base of the San Bernardino Mountains near the Newmark area in the Bunker Hill Basin of southern California. Water samples were collected from four multiple-depth well sites, from different depths within three production wells, and from two nearby streams; these samples were analyzed for major ions, selected trace elements, stable isotopes of oxygen and hydrogen (delta oxygen-18 and delta deuterium), tritium, and carbon-14. Within the production wells, variations in vertical flowrate with depth were recorded during pumped conditions using a standard spinner tool. Where saturated, the upper 200 feet of unconsolidated deposits contributed as much as 60 percent of the well discharge; deposits at depths greater than 700 feet contributed less than 10 percent. Chemical analyses indicate that three general zones of ground-water quality are present along a north-south section--an oxygenated zone near the base of the San Bernardino Mountains, an oxygen-depleted zone near the San Jacinto Fault, and a deeper zone characterized by concentrations of fluoride greater than 1 mg/L and by a general water-quality composition similar to that of base flow in East Twin Creek. The presence of tritium in water from wells along the section indicates that post-1952 recharge has moved rapidly through the valley-fill aquifer to depths as great as 800 feet. Carbon-14 data indicate that the maximum age of ground water, sampled at depths ranging from 600 to 1,000 feet, is less than 5,000 years before present. Ground water along the study section is much younger than ground water from similar depths in other nearby basins. Delta oxygen-18 and delta deuterium data indicate that as much as 25 percent of the discharge from some wells near the base of the San Bernardino Mountains is water that was imported from northern California. Improved knowledge of depth-dependent ground-water flow along this section can aid in the design of an effective strategy for basin management, including remediation of the Newmark area, which is designated by the U.S. Environmental Protection Agency as a Superfund cleanup site.

Water-Resources Investigations Report↗
USGS2015

An Arctic and Subarctic ostracode database: Biogeographic and paleoceanographic applications

A new Arctic Ostracode Database-2015 (AOD-2015) provides census data for 96 species of benthic marine Ostracoda from 1340 modern surface sediments from the Arctic Ocean and subarctic seas. Ostracoda is a meiofaunal, Crustacea group that secretes a bivalved calcareous (CaCO 3 ) shell commonly preserved in sediments. Arctic and subarctic ostracode species have ecological limits controlled by temperature, salinity, oxygen, sea ice, food, and other habitat-related factors. Unique species ecology, shell chemistry (Mg/Ca ratios, stable isotopes), and limited stratigraphic ranges make them a useful tool for paleoceanographic reconstructions and biostratigraphy. The database, described here, will facilitate the investigation of modern ostracode biogeography, regional community structure, and ecology. These data, when compared to downcore faunal data from sediment cores, will provide a better understanding of how the Arctic has been affected by climatic and oceanographic change during the Quaternary. Images of all species and biogeographic distribution maps for selected species are presented, with brief discussion of representative species’ biogeographic and ecological significance. Publication of AOD-2015 is open-sourced and will be available online at several public websites with latitude, longitude, water depth, and bottom water temperature for most samples. It includes material from Arctic abyssal plains and submarine ridges, continental slopes, and shelves of the Kara, Laptev, East Siberian, Chukchi, Beaufort Seas, and several subarctic regions.

Hydrobiologia↗
USGS1990

A spectral reflectance study (0.4-2.5 μm) of selected playa evaporite mineral deposits and related geochemical processes

Playa evaporite mineral deposits show major compositional variations related to differences in lithology, hydrology, and groundwater geochemistry. The use of visible and near-infrared (VNIR) spectral reflectance measurements as a technique for investigating the mineralogy of playa efflorescent crusts is examined. Samples of efflorescent crust were collected from 4 playa: Bristol Dry Lake, Saline Valley, Teels Marsh, and Rhodes Marsh--all located in eastern California and western Nevada. Laboratory and field spectral analyses coupled with X-ray diffraction analyses of the crusts yielded the following observations: VNIR spectra of unweathered salt crusts can be used to infer the general chemistry of near-surface brines; VNIR spectra are very sensitive for detecting minor hydrate mineral phases contained in mixtures with anhydrous, spectrally featureless, minerals such as halite (NaCl) and thernardite (Na2So4); borate minerals exhibit particularly strong VNIR spectral features that permit small amounts of borate to be detected in efflorescent salt crusts; remote sensing spectral measurements of playa efflorescent crusts may have applications in global studies of playa brines and minerals.

Conference Paper↗
USGS2006

Salinity and temperature tolerance experiments on selected Florida Bay mollusks

The ultimate goal of the Comprehensive Everglades Restoration Plan (CERP) is to restore and preserve the unique ecosystems of South Florida, including the estuaries. Understanding the effect of salinity and temperature changes, beyond typical oscillations, on the biota of South Florida's estuaries is a necessary component of achieving the goal of restoring the estuaries. The U.S. Geological Survey has been actively involved in researching the history of the South Florida Ecosystem, to provide targets, performance measures, and baseline data for restoration managers. These experiments addressed two aspects of ecosystem history research: 1) determining the utility of using molluscan shells as recorders of change in water chemistry parameters, primarily salinity, and 2) enhancing our in situ observations on modern assemblages by exceeding typically observed aquatic conditions. This set of experiments expanded our understanding of the effects of salinity, temperature and other water chemistry parameters on the reproduction, growth and overall survivability of key species of mollusks used in interpreting sediment core data. Observations on mollusks, plants and microbes made as part of these experiments have further refined our knowledge and understanding of the effects of ecosystem feedback and the role salinity and temperature play in ecosystem stability. The results have demonstrated the viability of several molluscan species as indicators of atypical salinity, and possibly temperature, modulations. For example Cerithium muscarum and Bulla striata demonstrated an ability to withstand a broad salinity and temperature range, with reproduction occurring in atypically high salinities and temperatures. These experiments also provided calibration data for the shell biogeochemistry of Chione cancellata and the possible use of this species as a water chemistry recorder. Observations made in the mesocosms, on a scale not normally observable in the field, have led to new questions about the influence of salinity on the localized ecosystem. The next phase of these experiments; to calibrate growth rate and reproductive viability in atypical salinities is currently underway.

Florida↗
USGS2007

Influence of Locally Derived Recharge on the Water Quality and Temperature of Springs in Hot Springs National Park, Arkansas

The hot springs of Hot Springs National Park consist of a mixture of water from two recharge components: a primary hot-water component and a secondary cold-water component. Widespread distribution of fractures enables mixing of the hot- and cold-water components of flow near the discharge area for the springs. Urbanization in the area near the hot springs of Hot Springs National Park has increased the potential for degradation of the quality of surface-water runoff and locally derived ground-water recharge to the hot springs. Previous studies by the U.S. Geological Survey have indicated that water from some cold-water springs and wells in the vicinity of Hot Springs, Arkansas, showed evidence of contamination and that water from locally derived cold-water recharge might contribute 25 percent of the total flow to the hot springs after storms. Water samples were collected during base-flow conditions at nine hot springs and two cold-water springs in September 2000. Nine hot springs and one cold-water spring were resampled in October 2001 after a storm that resulted in a measurable decrease in water temperature in selected hot springs. Water samples were analyzed for a variety of dissolved chemical constituents (nutrients, major ions, trace elements, pesticides, semivolatile compounds, isotopes, and radiochemicals), physical properties, field measurements, and bacteria. Comparison of analyses of samples collected during base-flow conditions from the springs in 2000 and during a storm event in 2001 with the results from earlier studies dating back to the late 1800's indicates that little change in major, minor, and trace constituent chemistry has occurred and that the water continues to be of excellent quality. Water-quality data show distinguishable differences in water chemistry of the springs during base-flow and stormflow conditions, indicating changing input of cold-water recharge relative to hot-water recharge. Silica, total dissolved solids, strontium, barium, and sulfate show statistically significant differences between the median values of base-flow and stormflow samples. While variations in these constituents do not degrade water quality, the differences do provide evidence of variability in the factors controlling water quality of the hot springs and show that water quality is influenced by the locally derived, cold-water component of flow to the springs. Water temperature was measured continuously (3-minute intervals) between August 2000 and October 2002 at four hot springs. Continuous water-temperature data at the springs provide no indication of persistent long-term change in water temperature through time. Short time-scale water-temperature decreases occur in response to mixing of hot-springs water with locally derived recharge after storm events; the magnitude of these decreases varied inversely with the amount of rainfall. Maximum decreases in water temperature for specific storms had a non-linear relation with the amount of precipitation measured for the events. Response time for water temperature to begin decreasing from baseline temperature as a result of storm recharge was highly variable. Some springs began decreasing from baseline temperature as quickly as 1 hour after the beginning of a storm; one spring had an 8-hour minimum response time to show a storm-related temperature decrease. Water-quality, water-temperature, isotopic, and radiochemical data provide multiple lines of evidence supporting the importance of the contribution of cold-water recharge to hot springs. All the springs sampled indicated some measure of influence from local recharge. Binary mixing models using silica and total dissolved solids indicate that cold-water recharge from stormflow contributes an estimated 10 to 31 percent of the flow of hot springs. Models using water temperature indicate that cold-water recharge from stormflow contributes an estimated 1 to 35 percent of the flow of the various hot springs. Alth

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