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At least 1,351 records · Page 75Linked to original sources
USGS2012

Heterogeneous redox conditions, arsenic mobility, and groundwater flow in a fractured-rock aquifer near a waste repository site in New Hampshire, USA

Anthropogenic sources of carbon from landfill or waste leachate can promote reductive dissolution of in situ arsenic (As) and enhance the mobility of As in groundwater. Groundwater from residential-supply wells in a fractured crystalline-rock aquifer adjacent to a Superfund site in Raymond, New Hampshire, USA, showed evidence of locally enhanced As mobilization in relatively reducing (mixed oxic-anoxic to anoxic) conditions as determined by redox classification and other lines of evidence. Redox classification was determined from geochemical indicators based on threshold concentrations of dissolved oxygen (DO), nitrate (NO 3- ), iron (Fe 2+ ), manganese (Mn 2+ ), and sulfate (SO 4 2- ). Redox conditions were evaluated also based on methane (CH 4 ), excess nitrogen gas (N 2 ) from denitrification, the oxidation state of dissolved As speciation (As(III) and As(V)), and several stable isotope ratios. Samples from the residential-supply wells primarily exhibit mixed redox conditions, as most have long open boreholes (typically 50–100 m) that receive water from multiple discrete fractures with contrasting groundwater chemistry and redox conditions. The methods employed in this study can be used at other sites to gauge redox conditions and the potential for As mobilization in complex fractured crystalline-rock aquifers where multiple lines of evidence are likely needed to understand As occurrence, mobility, and transport.

New Hampshire↗
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↗
USGS2015

Chemical concentrations and instantaneous loads, Green River to the Lower Duwamish Waterway near Seattle, Washington, 2013–15

In November 2013, U.S. Geological Survey streamgaging equipment was installed at a historical water-quality station on the Duwamish River, Washington, within the tidal influence at river kilometer 16.7 (U.S. Geological Survey site 12113390; Duwamish River at Golf Course at Tukwila, WA). Publicly available, real-time continuous data includes river streamflow, stream velocity, and turbidity. Between November 2013 and March 2015, the U.S. Geological Survey collected representative samples of water, suspended sediment, or bed sediment from the streamgaging station during 28 periods of differing flow conditions. Samples were analyzed by Washington-State-accredited laboratories for a large suite of compounds, including metals, dioxins/furans, semivolatile compounds including polycyclic aromatic hydrocarbons, pesticides, butytins, polychlorinated biphenyl (PCB) Aroclors and the 209 PCB congeners, volatile organic compounds, hexavalent chromium, and total and dissolved organic carbon. Metals, PCB congeners, and dioxins/furans were frequently detected in unfiltered-water samples, and concentrations typically increased with increasing suspended-sediment concentrations. Chemical concentrations in suspendedsediment samples were variable between sampling periods. The highest concentrations of many chemicals in suspended sediment were measured during summer and early autumn storm periods. Median chemical concentrations in suspended-sediment samples were greater than median chemical concentrations in fine bed sediment (less than 62.5 µm) samples, which were greater than median chemical concentrations in paired bulk bed sediment (less than 2 mm) samples. Suspended-sediment concentration, sediment particle-size distribution, and general water-quality parameters were measured concurrent with the chemistry sampling. From this discrete data, combined with the continuous streamflow record, estimates of instantaneous sediment and chemical loads from the Green River to the Lower Duwamish Waterway were calculated. For most compounds, loads were higher during storms than during baseline conditions because of high streamflow and high chemical concentrations. The highest loads occurred during dam releases (periods when stored runoff from a prior storm is released from the Howard Hanson Dam into the upper Green River) because of the high river streamflow and high suspended-sediment concentration, even when chemical concentrations were lower than concentrations measured during storm events.

Washington↗
USGS2011

Benthic habitat classification in Lignumvitae Key Basin, Florida Bay, using the U.S. Geological Survey Along-Track Reef Imaging System (ATRIS)

The Comprehensive Everglades Restoration Plan (CERP) funded in partnership between the U.S. Army Corps of Engineers, South Florida Water Management District, and other Federal, local and Tribal members has in its mandate a guideline to protect and restore freshwater flows to coastal environments to pre-1940s conditions (CERP, 1999). Historic salinity data are sparse for Florida Bay, so it is difficult for water managers to decide what the correct quantity, quality, timing, and distribution of freshwater are to maintain a healthy and productive estuarine ecosystem. Proxy records of seasurface temperature (SST) and salinity have proven useful in south Florida. Trace-element chemistry on foraminifera and molluscan shells preserved in shallow-water sediments has provided some information on historical salinity and temperature variability in coastal settings, but little information is available for areas within the main part of Florida Bay (Brewster-Wingard and others, 1996). Geochemistry of coral skeletons can be used to develop subannually resolved proxy records for SST and salinity. Previous studies suggest corals, specifically Solenastrea bournoni, present in the lower section of Florida Bay near Lignumvitae Key, may be suitable for developing records of SST and salinity for the past century, but the distribution and species composition of the bay coral community have not been well documented (Hudson and others, 1989; Swart and others, 1999). Oddly, S. bournoni thrives in the study area because it can grow on a sandy substratum and can tolerate highly turbid water. Solenastrea bournoni coral heads in this area should be ideally located to provide a record (~100-150 years) of past temperature and salinity variations in Florida Bay. The goal of this study was to utilize the U.S. Geological Survey's (USGS) Along-Track Reef Imaging System (ATRIS) capability to further our understanding of the abundance, distribution, and size of corals in the Lignumvitae Key Basin. The study area was subdivided into four areas whereby corals and other benthic habitats were classified based on ATRIS imagery.

Florida↗
USGS2007

Water-Quality Characteristics of Cottonwood Creek, Taggart Creek, Lake Creek, and Granite Creek, Grand Teton National Park, Wyoming, 2006

To address water-resource management objectives of the National Park Service in Grand Teton National Park, the U.S. Geological Survey in cooperation with the National Park Service has conducted water-quality sampling on streams in the Snake River headwaters area. A synoptic study of streams in the western part of the headwaters area was conducted during 2006. Sampling sites were located on Cottonwood Creek, Taggart Creek, Lake Creek, and Granite Creek. Sampling events in June, July, August, and October were selected to characterize different hydrologic conditions and different recreational-use periods. Stream samples were collected and analyzed for field measurements, major-ion chemistry, nutrients, selected trace elements, pesticides, and suspended sediment. Water types of Cottonwood Creek, Taggart Creek, Lake Creek, and Granite Creek were calcium bicarbonate. Dissolved-solids concentrations were dilute in Cottonwood Creek and Taggart Creek, which drain Precambrian-era rocks and materials derived from these rocks. Dissolved-solids concentrations ranged from 11 to 31 milligrams per liter for samples collected from Cottonwood Creek and Taggart Creek. Dissolved-solids concentrations ranged from 55 to 130 milligrams per liter for samples collected from Lake Creek and Granite Creek, which drain Precambrian-era rocks and Paleozoic-era rocks and materials derived from these rocks. Nutrient concentrations generally were small in samples collected from Cottonwood Creek, Taggart Creek, Lake Creek, and Granite Creek. Dissolved-nitrate concentrations were the largest in Taggart Creek. The Taggart Creek drainage basin has the largest percentage of barren land cover of the basins, and subsurface waters of talus slopes may contribute to dissolved-nitrate concentrations in Taggart Creek. Pesticide concentrations, trace-element concentrations, and suspended-sediment concentrations generally were less than laboratory reporting levels or were small for all samples. Water-quality characteristics of streams in the western part of the Snake River headwaters area were compared to water-quality characteristics of streams sampled in 2002 in the eastern part of the headwaters area. The median dissolved-solids concentration (55 milligrams per liter) for samples collected from western streams was smaller than the median dissolved-solids concentration (125 milligrams per liter) for samples collected from eastern streams. The small dissolved-solids concentrations in the western streams are a result of the large areas underlain by resistant Precambrian-era rocks that compose the Teton Range compared to the more erodable Mesozoic-era sedimentary rocks that compose the mountains in the eastern part of the headwaters area. The Teton Range also receives higher annual precipitation than the mountains in the east. The median total-nitrogen concentration (0.17 milligram per liter) in samples collected from streams in the western part of the Snake River headwaters area was larger than the median concentration (0.10 milligram per liter) for samples collected from streams in the eastern part of the headwaters area, in part because of larger dissolved-nitrate concentrations in samples from the western streams compared to the eastern streams. In contrast, total-phosphorus concentrations generally were larger for samples collected from eastern streams. Large total-phosphorus concentrations in the eastern streams were associated with large suspended-sediment concentrations. The source of the phosphorus and sediment probably is Mesozoic-era sedimentary rocks of marine origin that underlie parts of the eastern drainage basins.

Scientific Investigations Report↗
USGS1995

Chemistry and petrography of calcite in the KTB pilot borehole, Bavarian Oberpfalz, Germany

The KTB pilot borehole in northeast Bavaria, Germany, penetrates 4000 m of gneiss, amphibolite, and subordinate calc-silicate, lamprophyre and metagabbro. There are three types of calcite in the drilled section: 1) metamorphic calcite in calc-silicate and marble; 2) crack-filling calcite in all lithologies; and 3) replacement calcite in altered minerals. Crack-filling and replacement calcite postdate metamorphic calcite. Multiple calcite generations in individual cracks suggest that different generations of water repeatedly flowed through the same cracks. Crack-filling mineral assemblages that include calcite originally formed at temperatures of 150-350??C. Presently, crack-filling calcite is in chemical and isotopic equilibrium with saline to brackish water in the borehole at temperatures of ???120??C. The saline to brackish water contains a significant proportion of meteoric water. Re-equilibration of crack-filling calcite to lower temperatures means that calcite chemistry tells us little about water-rock interactions in the crystal section of temperatures higher than ~120??C. -from Author

Chemical Geology↗
USGS2003

Landscape linkages between geothermal activity and solute composition and ecological response in surface waters draining the Atlantic slope of Costa Rica

Surface waters draining three different volcanoes in Costa Rica, ranging from dormant to moderately active to explosive, have a wide range of solute compositions that partly reflects the contribution of different types of solute-rich, geothermal waters. Three major physical transport vectors affect flows of geothermally derived solutes: thermally driven convection of volcanic gases and geothermal fluids; lateral and gravity-driven downward transport of geothermal fluids; and wind dispersion of ash, gases, and acid rain. Specific vector combinations interact to determine landscape patterns in solute chemistry and biota: indicator taxa of algae and bacteria reflect factors such as high temperature, wind-driven or hydrologically transported acidity, high concentrations of various solutes, and chemical precipitation reactions. Many streams receiving geothermally derived solutes have high levels of soluble reactive phosphorus (SRP) (up to 400 µ g liter −1 ), a nutrient that is typically not measured in geochemical studies of geothermal waters. Regional differences in levels of SRP and other solutes among volcanoes were typically not significant due to high local variation in solute levels among geothermally modified streams and between geothermally modified and unmodified streams on each volcano. Geothermal activity along the volcanic spine of Costa Rica provides a natural source of phosphorus, silica, and other solutes and plays an important role in determining emergent landscape patterns in the solute chemistry of surface waters and aquatic biota.

Limnology and Oceanography↗
USGS2024

Pesticide concentrations of surface water and suspended sediment in Yolo By-Pass and Cache Slough Complex, California, 2019–2021

Managed flow pulses in the north Sacramento-San Joaquin Delta are an adaptive management tool used in efforts to enhance food availability in delta smelt ( Hypomesus transpacificus ) habitat as part of the North Delta Food Subsidies Action. The California Department of Water Resources (DWR) monitors non-managed seasonal and local flow pulses and managed flow pulses from agricultural drainage or main stem Sacramento River water redirected through Yolo By-Pass. Augmented flow pulses are hypothesized to improve net positive flow during summer and fall in Yolo By-Pass and enhance plankton availability in delta smelt habitat in Cache Slough complex. However, flow pulses may also result in unintended negative effects of increased pesticides that are transported through Yolo By-Pass. Here, we evaluate pesticides in surface water and suspended sediment correlated with flow pulses in Yolo By-Pass during the 2019–21 calendar years. Surface-water and suspended-sediment samples were collected by DWR personnel. Water samples were analyzed at the U.S. Geological Survey Organic Chemistry Research Laboratory in Sacramento, California, for a suite of as many as 178 current-use pesticides and pesticide degradates using gas chromatography with mass spectrometry (GC/MS), gas chromatography with tandem mass spectrometry, and liquid chromatography with tandem mass spectrometry. Suspended sediments filtered from water samples were analyzed for a suite of as many as 173 current-use pesticides and pesticide degradates. There were 52 different current-use pesticides and pesticide degradates detected in water samples collected throughout the study. Concentrations ranged from below method detection limits to 4,070 nanograms per liter. Five different compounds in water samples were detected with concentrations above U.S. Environmental Protection Agency aquatic life benchmarks. In suspended-sediment samples collected throughout the study, eight different current-use pesticides and pesticide degradates were detected. Total pesticide concentrations were highest at surface-water sites in the northern end of Yolo By-Pass and decreased farther downstream during the same sampling events. Total pesticide concentrations generally were higher for most surface-water sites immediately before or during the managed flow pulse in 2019 versus after the flow pulse. Finally, mean total pesticide concentrations for each surface-water site generally were higher during all of 2019 than 2021, regardless of sampling period.

California↗
USGS2019

Use of high-throughput screening results to prioritize chemicals for potential adverse biological effects within a West Virginia Watershed

Organic chemicals from industrial, agricultural, and residential activities can enter surface waters through regulated and unregulated discharges, combined sewer overflows, stormwater runoff, accidental spills, and leaking septic-conveyance systems on a daily basis. The impact of point and nonpoint contaminant sources can result in adverse biological effects for organisms living in or near surface waters. Assessing the adverse or toxic effects that may result when exposure occurs is complicated by the fact that many commonly used chemicals lack toxicity information or water quality standards. To address these challenges, an exposure-activity ratio (EAR) screening approach was used to prioritize environmental chemistry data in a West Virginia watershed (Wolf Creek). Wolf Creek is a drinking water source and recreation resource with documented water quality impacts from point and nonpoint sources. The EAR screening approach uses high-throughput screening (HTS) data from ToxCast as a method of integrating environmental chemical occurrence and biological effects data. Using water quality schedule 4433, which targets 69 organic waste compounds typically found in domestic and industrial wastewater, chemicals were screened for potential adverse biological affects at multiple sites in the Wolf Creek watershed. Cumulative EAR mixture values were greatest at Sites 2 and 3, where bisphenol A (BPA) and pentachlorophenol exhibited maximum EAR values of 0.05 and 0.002, respectively. Site 2 is downstream of an unconventional oil and gas (UOG) wastewater disposal facility with documented water quality impacts. Low-level organic contaminants were found at all sample sites in Wolf Creek, except Site 10, where Wolf Creek enters the New River. The application of an EAR screening approach allowed our study to extend beyond traditional environmental monitoring methods to identify multiple sites and chemicals that warrant further investigation.

West Virginia↗
USGS1992

Assessment of sediment contamination at Great Lakes Areas of Concern: the ARCS Program Toxicity-Chemistry Work Group strategy

In response to a mandate in Section 118(c)(3) of the Water Quality Act of 1987, a program called Assessment and Remediation of Contaminated Sediments (ARCS) was established. Four technical work groups were formed. This paper details the research strategy of the Toxicity-Chemistry Work Group. The Work Group's general objectives are to develop survey methods and to map the degree of contamination and toxicity in bottom sediments at three study areas, which will serve as guidance for future surveys at other locations. A related objective is to use the data base that will be generated to calculate sediment quality concentrations by several methods. The information needed to achieve these goals will be collected in a series of field surveys at three areas: Saginaw Bay (MI), Grand Calumet River (IN), and Buffalo River (NY). Assessments of the extent of contamination and potential adverse effects of contaminants in sediment at each of these locations will be conducted by collecting samples for physical characterization, toxicity testing, mutagenicity testing, chemical analyses, and fish bioaccumulation assays. Fish populations will be assessed for tumors and external abnormalities, and benthic community structure will be analyzed. A mapping approach will use low-cost indicator parameters at a large number of stations, and will extrapolate by correlation from traditional chemical and biological studies at a smaller number of locations. Sediment toxicity testing includes elutriate, pore water and whole sediment bioassays in a three-tiered framework. In addition to the regular series of toxicity tests at primary mater stations, some stations are selected for a more extensive suite of tests.

Journal of Aquatic Ecosystem Health↗
USGS2020

Geochemical characterization of groundwater evolution south of Grand Canyon, Arizona (USA)

Better characterization of the geochemical evolution of groundwater south of Grand Canyon, Arizona (USA), is needed to understand natural conditions and assess potential effects from breccia-pipe uranium mining in the region. Geochemical signatures of groundwater at 28 sampling locations were evaluated; baseline concentrations for select trace elements (As, B, Ba, Cr, Li, Mo, Rb, Se, Sr, Th, Tl, U, V) were established, and anomalous chemistry characteristics were identified. Concentrations at some groundwater sites exceeded the USEPA drinking water standard for As of 10 μg/L (Red Canyon, Miners, JT, Havasu, and Warm Springs) and U of 30 μg/L (Salt Creek Spring). Four springs from the study area (Blue, Havasu, Fern, and Warm Springs) had unique chemistry, which may indicate a deep flow path or potential contribution of fluids from lower in the crust. Other springs in the study area were distinguished by major anion water type: sulfate, bicarbonate, and a mixture of the two. Water type distinctions were somewhat spatially segregated, with sulfate type present on the western side of the study area, bicarbonate type on the eastern side, and a mixture of the two interspersed between the endmember sites. Sulfate-type water from this study area had low strontium isotopic ratio (87Sr/86Sr) values. The location of spring discharge within single drainages of the Grand Canyon may influence chemistry, as groundwater discharging from bedrock was altered after flowing through alluvial material. Geochemical analysis of groundwater in Grand Canyon indicates the importance of continued monitoring and better understanding of short-term chemical fluctuations.

Arizona↗
USGS2015

Seasonal microbial and environmental parameters at Crocker Reef, Florida Keys, 2014–2015

Crocker Reef, located on the outer reef tract of the Florida Keys (fig. 1), was the site of an integrated “reefscape characterization” effort focused on calcification and related biogeochemical processes as part of the U.S. Geological Survey (USGS) C oral R eef E cosystem ST udies (CREST) project. It is characterized as a senile or dead reef, with only scattered stony coral colonies and areas of sand and rubble. It was chosen as an end-member for later comparison to sites with a healthy, growing reef framework. The CREST reefscape characterization included two intensive seasonal sampling trips to capture summer (July 8–17, 2014) and winter (January 29–February 5, 2015) conditions. This report presents water column microbial and environmental data collected for use as metadata in future publications examining reef metabolic processes via metagenomes derived from water samples and fine-scale temporal and spatial carbonate chemistry measurements. Microbial measurements included enumeration of total bacteria, enumeration of virus-like particles, and plate counts of Vibrio spp. colony-forming units (CFU). These measurements were intended to give a sense of any seasonal changes in the total microbial load and to provide an indication of water quality. Additional environmental parameters measured included water temperature, salinity, dissolved oxygen, and pH. Four sites (table 1) were intensively sampled for periods of approximately 48 hours during summer (July 2014) and winter (January–February 2015), during which water samples were collected every 4 hours for analysis, except when prevented by weather conditions.

Florida↗
USGS1992

Rare earth, major and trace element composition of Leg 127 sediments

The relative effects of paleoceanographic and paleogeographic variations, sediment lithology, and diagenetic processes on the final preserved chemistry of Japan Sea sediments are evaluated by investigating the rare earth element (REE), major element, and trace element concentrations in 59 squeeze-cake whole-round and 27 physical-property sample residues from Sites 794, 795, and 797, cored during ODP Leg 127. The most important variation in sedimentary chemical composition is the increase in SiO2 concentration through the Pliocene diatomaceous sequences, which dilutes most other major and trace element components by various degrees. This biogenic input is largest at Site 794 (Yamato Basin), moderately developed at Site 797 (Yamato Basin), and of only minor importance at Site 795 (Japan Basin), potentially reflecting basinal contrasts in productivity with the Yamato Basin recording greater biogenic input than the Japan Basin and with the easternmost sequence of Site 794 lying beneath the most productive waters. There are few systematic changes in solid-phase chemistry resulting from the opal-A/opal-CT or opal-CT/quartz silica phase transformations. Most major and trace element concentrations are controlled by the aluminosilicate fraction of the sediment, although the effects of diagenetic silica phases and manganese carbonates are of localized importance. REE total abundances (IREE) in the Japan Sea are strongly dependent upon the paleoceanographic position of a given site with respect to terrigenous and biogenic sources. REE concentrations at Site 794 overall correspond well to aluminosilicate chemical indices and are strongly diluted by SiO2 within the upper Miocene-Pliocene diatomaceous sequence. Eu/Eu* values at Site 794 reach a maximum through the diatomaceous interval as well, most likely suggesting an association of Eu/Eu* with the siliceous component, or reflecting slight incorporation of a detrital feldspar phase. XREE at Site 795 also is affiliated strongly with aluminosilicate phases and yet is diluted only slightly by siliceous input. At Site 797, ΣRE E is not as clearly associated with the aluminosilicate fraction, is correlated moderately to siliceous input, and may be sporadically influenced by detrital heavy minerals originating from the nearby rifted continental fragment composing the Yamato Rise. Ce/Ce* profiles at all three sites increase essentially monotonically with depth and record progressive diagenetic LREE fractionation. The observed Ce/Ce* increases are not responding to changes in the paleoceanographic oxygenation state of the overlying water, as there is no independent evidence to suggest the proper Oceanographic conditions. Ce/Ce* correlates slightly better with depth than with age at the two Yamato Basin sites. The downhole increase in Ce/Ce* at Sites 794 and 797 is a passive response to the diagenetic transfer of LREE (except Ce) from sediment to interstitial water. At Site 795, the overall lack of correlation between Ce/Ce* and La/Y^ suggests that other processes mask the diagenetic behavior of all LREEs. First-order calculations of the Ce budget in Japan Sea waters and sediment indicate that ~20% of the excess Ce adsorbed by settling particles is recycled within the water column and that an additional -38% is recycled at or near the seafloor. Thus, because the remaining excess Ce is only -10% of the total Ce, there is not a large source of Ce to the deeply buried sediment, further suggesting that the downhole increase in Ce/Ce* is a passive response to diagenetic behavior of the other LREEs. The REE chemistry of Japan Sea sediment therefore predicts successive downhole addition of LREEs to deeply buried interstitial waters.

Conference Paper↗
USGS1983

Evidence for acid-precipitation-induced trends in stream chemistry at hydrologic bench-mark stations

Ten- to 15-year water-quality records from a network of headwater sampling stations show small declines in stream sulfate concentrations at stations in the northeastern quarter of the Nation and small increases in sulfate at most southeastern and western sites. The regional pattern of stream sulfate trends is similar to that reported for trends in S02 emissions to the atmosphere during the same period. Trends in the ratio of alkalinity to total major cation concentrations at the stations follow an inverse pattern of small increases in the Northeast and small, but widespread decreases elsewhere. The undeveloped nature of the sampled basins and the magnitude and direction of observed changes in relation to SO2 emissions support the hypothesis that the observed patterns in water quality trends reflect regional changes in the rates of acid deposition.

Circular↗
USGS2009

Herbicide metabolites in surface water and groundwater: Introduction and overview

Several future research topics for herbicide metabolites in surface and ground water are outlined in this chapter. They are herbicide usage, chemical analysis of metabolites, and fate and transport of metabolites in surface and ground water. These three ideas follow the themes in this book, which are the summary of a symposium of the American Chemical Society on herbicide metabolites in surface and ground water. First, geographic information systems allow the spatial distribution of herbicide-use data to be combined with geochemical information on fate and transport of herbicides. Next these two types of information are useful in predicting the kinds of metabolites present and their probable distribution in surface and ground water. Finally, methods development efforts may be focused on these specific target analytes. This chapter discusses these three concepts and provides an introduction to this book on the analysis, chemistry, and fate and transport of herbicide metabolites in surface and ground water.

ACS Symposium Series↗
USGS2019

Probabilistic relationships between acid-base chemistry and fish assemblages in streams of the western Adirondack Mountains, New York, USA

Surface waters across much of the Adirondacks of New York were acidified in the late 20th century but began to recover after the 1990 amendments to the Clean Air Act. Little data, however, were available to characterize biological impacts and predict recovery of fish assemblages in regional streams. Quantitative fish and chemistry surveys were completed in 47 headwater streams during summer 2014-16 to develop logistic (probabilistic) models that characterize the status of contemporary fish assemblages and predict how different N and S deposition loads may affect future fish assemblages. Models for Ali and richness ≥1 species, ANC and total density >400 fish/0.1 ha, ANC and total biomass >1500 g/0.1, presence of Brook Trout, trout density >200 fish/0.1 ha, and trout biomass >1000 g/0.1 ha were suitable for evaluating community and population responses to changes in acid-base chemistry. Anticipated changes in national (US) secondary standards for atmospheric emissions of NOx and SOx to achieve target N and S deposition loads will alter acid-base chemistry and the probabilities for observing various levels of fish metrics in streams across the region and elsewhere.

New York↗
USGS2013

Mercury and methylmercury dynamics in the hyporheic zone of an Oregon stream

The role of the hyporheic zone in mercury (Hg) cycling has received limited attention despite the biogeochemically active nature of this zone and, thus, its potential to influence Hg behavior in streams. An assessment of Hg geochemistry in the hyporheic zone of a coarse-grained island in the Coast Fork Willamette River in Oregon, USA, illustrates the spatially dynamic nature of this region of the stream channel for Hg mobilization and attenuation. Hyporheic flow through the island was evident from the water-table geometry and supported by hyporheic-zone chemistry distinct from that of the bounding groundwater system. Redox-indicator species changed abruptly along a transect through the hyporheic zone, indicating a biogeochemically reactive stream/hyporheic-zone continuum. Dissolved organic carbon (DOC), total Hg, and methylmercury (MeHg) concentrations increased in the upgradient portion of the hyporheic zone and decreased in the downgradient region. Total Hg (collected in 2002 and 2003) and MeHg (collected in 2003) were correlated with DOC in hyporheic-zone samples: r 2 =0.63 (total Hg-DOC, 2002), 0.73 (total Hg-DOC, 2003), and 0.94 (MeHg-DOC, 2003). Weaker Hg/DOC association in late summer 2002 than in early summer 2003 may reflect seasonal differences in DOC reactivity. Observed correlations between DOC and both total Hg and MeHg reflect the importance of DOC for Hg mobilization, transport, and fate in this hyporheic zone. Correlations with DOC provide a framework for conceptualizing and quantifying Hg and MeHg dynamics in this region of the stream channel, and provide a refined conceptual model of the role hyporheic zones may play in aquatic ecosystems.

Water, Air, & Soil Pollution↗