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Sample records for bay watersheds usa

  1. Supply and dispersal of flood sediment from a steep, tropical watershed: Hanalei Bay, Kaua'i, Hawai'i, USA

    USGS Publications Warehouse

    Draut, A.E.; Bothner, Michael H.; Field, M.E.; Reynolds, R.L.; Cochran, S.A.; Logan, J.B.; Storlazzi, C.D.; Berg, C.J.

    2009-01-01

    In contrast to many small, mountainous watersheds in temperate coastal regions, where fluvial discharge and wave energy commonly coincide, deposition and reworking of tropical flood sediment can be seasonally decoupled, and this has important implications for coral-reef ecosystems. An understanding of the interaction between tropical flood sedimentation and wave climate is essential to identifying and mitigating effects of watershed changes on coral reefs as urbanization and climate change proceed. Sedimentary facies and isotopic properties of sediment in Hanalei Bay, on the island of Kaua'i, Hawai'i, USA, were used to assess deposition and reworking of flood deposits from the Hanalei River in a case study demonstrating the potential ecosystem effects of runoff from a steep, tropical watershed. In Hanalei Bay, the youngest and thickest terrigenous sediment was consistently present near the river mouth and in a bathymetric depression that acted as at least a temporary sediment sink. During this 2 yr study, the largest flood events occurred in late winter and spring 2006; substantial terrestrial sediment delivered by those floods still remained in the bay as of June 2006 because oceanic conditions were not sufficiently energetic to transport all of the sediment offshore. Additional sediment was deposited in the bay by a summer 2006 flood that coincided with seasonal low wave energy. In most years, flood sediment accumulating in the bay and on its fringing reefs would be remobilized and advected out of the bay during winter, when the wave climate is energetic. Turbidity and sedimentation on corals resulting from late spring and summer floods during low wave energy could have a greater impact on coral-reef ecosystems than floods in other seasons, an effect that could be exacerbated if the incidence and sediment load of tropical summer floods increase due to urbanization and climate change. ?? 2008 Geological Society of America.

  2. Clean Watersheds for a Clean Bay Project

    EPA Pesticide Factsheets

    Information about the SFBWQPClean Watersheds for a Clean Bay Project: Implementing the PCB TMDL, part of an EPA competitive grant program to improve SF Bay water quality focused on restoring impaired waters and enhancing aquatic resources.

  3. Contemporary Land Change Alters Fish Communities in a San Francisco Bay Watershed, California, U.S.A.

    PubMed Central

    Cervantes-Yoshida, Kristina; Leidy, Robert A.; Carlson, Stephanie M.

    2015-01-01

    Urbanization is one of the leading threats to freshwater biodiversity, and urban regions continue to expand globally. Here we examined the relationship between recent urbanization and shifts in stream fish communities. We sampled fishes at 32 sites in the Alameda Creek Watershed, near San Francisco, California, in 1993–1994 and again in 2009, and we quantified univariate and multivariate changes in fish communities between the sampling periods. Sampling sites were classified into those downstream of a rapidly urbanizing area (“urbanized sites”), and those found in less impacted areas (“low-impacted sites”). We calculated the change from non-urban to urban land cover between 1993 and 2009 at two scales for each site (the total watershed and a 3km buffer zone immediately upstream of each site). Neither the mean relative abundance of native fish nor nonnative species richness changed significantly between the survey periods. However, we observed significant changes in fish community composition (as measured by Bray-Curtis dissimilarity) and a decrease in native species richness between the sampling periods at urbanized sites, but not at low-impacted sites. Moreover, the relative abundance of one native cyprinid (Lavinia symmetricus) decreased at the urbanized sites but not at low-impacted sites. Increased urbanization was associated with changes in the fish community, and this relationship was strongest at the smaller (3km buffer) scale. Our results suggest that ongoing land change alters fish communities and that contemporary resurveys are an important tool for examining how freshwater taxa are responding to recent environmental change. PMID:26580560

  4. Chesapeake Bay Watershed Implementation Plans (WIPs)

    EPA Pesticide Factsheets

    This page provides an overview of Watershed Implementation Plans (WIP) and how they play an important role in restoring the Chesapeake Bay. The page also provides links to each jurisdiction's Phase I, II, and III WIP.

  5. Chesapeake bay watershed land cover data series

    USGS Publications Warehouse

    Irani, Frederick M.; Claggett, Peter R.

    2010-01-01

    To better understand how the land is changing and to relate those changes to water quality trends, the USGS EGSC funded the production of a Chesapeake Bay Watershed Land Cover Data Series (CBLCD) representing four dates: 1984, 1992, 2001, and 2006. EGSC will publish land change forecasts based on observed trends in the CBLCD over the coming year. They are in the process of interpreting and publishing statistics on the extent, type and patterns of land cover change for 1984-2006 in the Bay watershed, major tributaries and counties.

  6. A Hydrological Model of the Mobile River Watershed, Southeastern USA

    NASA Astrophysics Data System (ADS)

    Alarcon, Vladimir J.; McAnally, William; Diaz-Ramirez, Jairo; Martin, James; Cartwright, John

    2009-08-01

    A hydrological model of the Mobile Bay watershed located in the northern Gulf of Mexico, (Alabama, USA) is presented. The modeling of hydrological processes is performed using the Hydrological Simulation Program Fortran (HSPF). The project region was divided into two sectors for simplifying the modeling task: an upland watershed (that included streams not draining directly to the Mobile Estuary), and several watersheds of selected streams that drain directly to the Mobile estuary (namely: Fish River, Magnolia River, and Chickasaw Creek). The Better Assessment Science Integrating Point & Nonpoint Sources (BASINS) GIS system was used to perform most of the geospatial operations, although ArcGis and ArcInfo were also used to complement geospatial processing that was not available in BASINS.

  7. 75 FR 11837 - Chesapeake Bay Watershed Initiative

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-12

    ..., but not exclusive, consideration to producers' applications in the following river basins: Susquehanna River, Shenandoah River, Potomac River (including North and South), and the Patuxent River. The... restore, enhance, and conserve soil, air, and related resources in the Chesapeake Bay watershed...

  8. Short-term variability of 7Be atmospheric deposition and watershed response in a Pacific coastal stream, Monterey Bay, California, USA

    USGS Publications Warehouse

    Conaway, Christopher H.; Storlazzi, Curt D.; Draut, Amy E.; Swarzenski, Peter W.

    2013-01-01

    Beryllium-7 is a powerful and commonly used tracer for environmental processes such as watershed sediment provenance, soil erosion, fluvial and nearshore sediment cycling, and atmospheric fallout. However, few studies have quantified temporal or spatial variability of 7Be accumulation from atmospheric fallout, and parameters that would better define the uses and limitations of this geochemical tracer. We investigated the abundance and variability of 7Be in atmospheric deposition in both rain events and dry periods, and in stream surface-water samples collected over a ten-month interval at sites near northern Monterey Bay (37°N, 122°W) on the central California coast, a region characterized by a rainy winters, dry summers, and small mountainous streams with flashy hydrology. The range of 7Be activity in rainwater samples from the main sampling site was 1.3–4.4 Bq L−1, with a mean (±standard deviation) of 2.2 ± 0.9 Bq L−1, and a volume-weighted average of 2.0 Bq L−1. The range of wet atmospheric deposition was 18–188 Bq m−2 per rain event, with a mean of 72 ± 53 Bq m−2. Dry deposition fluxes of 7Be ranged from less than 0.01 up to 0.45 Bq m−2 d−1, with an estimated dry season deposition of 7 Bq m−2 month−1. Annualized 7Be atmospheric deposition was approximately 1900 Bq m−2 yr−1, with most deposition via rainwater (>95%) and little via dry deposition. Overall, these activities and deposition fluxes are similar to values found in other coastal locations with comparable latitude and Mediterranean-type climate. Particulate 7Be values in the surface water of the San Lorenzo River in Santa Cruz, California, ranged from −1 to 0.6 Bq g−1, with a median activity of 0.26 Bq g−1. A large storm event in January 2010 characterized by prolonged flooding resulted in the entrainment of 7Be-depleted sediment, presumably from substantial erosion in the watershed. There were too few particulate 7Be data over the storm to accurately model a 7Be load

  9. Sediment calibration strategies of Phase 5 Chesapeake Bay watershed model

    USGS Publications Warehouse

    Wu, J.; Shenk, G.W.; Raffensperger, J.; Moyer, D.; Linker, L.C.; ,

    2005-01-01

    Sediment is a primary constituent of concern for Chesapeake Bay due to its effect on water clarity. Accurate representation of sediment processes and behavior in Chesapeake Bay watershed model is critical for developing sound load reduction strategies. Sediment calibration remains one of the most difficult components of watershed-scale assessment. This is especially true for Chesapeake Bay watershed model given the size of the watershed being modeled and complexity involved in land and stream simulation processes. To obtain the best calibration, the Chesapeake Bay program has developed four different strategies for sediment calibration of Phase 5 watershed model, including 1) comparing observed and simulated sediment rating curves for different parts of the hydrograph; 2) analyzing change of bed depth over time; 3) relating deposition/scour to total annual sediment loads; and 4) calculating "goodness-of-fit' statistics. These strategies allow a more accurate sediment calibration, and also provide some insightful information on sediment processes and behavior in Chesapeake Bay watershed.

  10. Modeling nitrogen cycling in forested watersheds of Chesapeake Bay

    SciTech Connect

    Hunsaker, C.T.; Garten, C.T.; Mulholland, P.J.

    1995-03-01

    The Chesapeake Bay Agreement calls for a 40% reduction of controllable phosphorus and nitrogen to the tidal Bay by the year 2000. To accomplish this goal the Chesapeake Bay Program needs accurate estimates of nutrient loadings, including atmospheric deposition, from various land uses. The literature was reviewed on forest nitrogen pools and fluxes, and nitrogen data from research catchments in the Chesapeake Basin were identified. The structure of a nitrogen module for forests is recommended for the Chesapeake Bay Watershed Model along with the possible functional forms for fluxes.

  11. DEVELOP Chesapeake Bay Watershed Hydrology - UAV Sensor Web

    NASA Astrophysics Data System (ADS)

    Holley, S. D.; Baruah, A.

    2008-12-01

    The Chesapeake Bay is the largest estuary in the United States, with a watershed extending through six states and the nation's capital. Urbanization and agriculture practices have led to an excess runoff of nutrients and sediment into the bay. Nutrients and sediment loading stimulate the growth of algal blooms associated with various problems including localized dissolved oxygen deficiencies, toxic algal blooms and death of marine life. The Chesapeake Bay Program, among other stakeholder organizations, contributes greatly to the restoration efforts of the Chesapeake Bay. These stakeholders contribute in many ways such as monitoring the water quality, leading clean-up projects, and actively restoring native habitats. The first stage of the DEVELOP Chesapeake Bay Coastal Management project, relating to water quality, contributed to the restoration efforts by introducing NASA satellite-based water quality data products to the stakeholders as a complement to their current monitoring methods. The second stage, to be initiated in the fall 2008 internship term, will focus on the impacts of land cover variability within the Chesapeake Bay Watershed. Multiple student led discussions with members of the Land Cover team at the Chesapeake Bay Program Office in the DEVELOP GSFC 2008 summer term uncovered the need for remote sensing data for hydrological mapping in the watershed. The Chesapeake Bay Program expressed in repeated discussions on Land Cover mapping that significant portions of upper river areas, streams, and the land directly interfacing those waters are not accurately depicted in the watershed model. Without such hydrological mapping correlated with land cover data the model will not be useful in depicting source areas of nutrient loading which has an ecological and economic impact in and around the Chesapeake Bay. The fall 2008 DEVELOP team will examine the use of UAV flown sensors in connection with in-situ and Earth Observation satellite data. To maximize the

  12. The Bear Brook Watershed, Maine (BBWM), USA

    USGS Publications Warehouse

    Norton, S.; Kahl, J.; Fernandez, I.; Haines, T.; Rustad, L.; Nodvin, S.; Scofield, J.; Strickland, T.; Erickson, H.; Wigington, P.; Lee, J.

    1999-01-01

    The Bear Brook Watershed Manipulation project in Maine is a paired calibrated watershed study funded by the U.S. EPA. The research program is evaluating whole ecosystem response to elevated inputs of acidifying chemicals. The consists of a 2.5 year calibration period (1987-1989), nine years of chemical additions of (NH4)2SO4 (15N- and 34S-enriched for several years) to West Bear watershed (1989-1998), followed by a recovery period. The other watershed, East Bear, serves as a reference. Dosing is in six equal treatments/yr of 1800 eq SO4 and NH4/ha/yr, a 200% increase over 1988 loading (wet plus dry) for SO4 300% for N (wet NO3 + NH4). The experimental and reference watersheds are forested with mixed hard- and softwoods, and have thin acidic soils, areas of 10.2 and 10.7 ha and relief of 210 m. Thin till of variable composition is underlain by metasedimentary pelitic rocks and calc-silicate gneiss intruded by granite dikes and sills. For the period 1987-1995, precipitation averaged 1.4 m/yr, had a mean pH of 4.5, with SO4, NO3, and NH4 concentrations of 26, 14, and 7 ??eq/L, respectively. The nearly perrenial streams draining each watershed have discharges ranging from 0 (East Bear stops flowing for one to two months per year) to 150 L/sec. Prior to manipulation, East Bear and West Bear had a volume weighted annual mean pH of approximately 5.4, alkalinity = 0 to 4 ??eq/L, total base cations = 184 ??eq/L (sea-salt corrected = 118 ??eq/L), and SO4 = 100 to 111 ??eq/L. Nitrate ranged from 0 to 30 ??eq/L with an annual mean of 6 to 25 ??eq/L; dissolved organic carbon (DOC) ranged from 1 to 7 mg/L but was typically less than 3. Episodic acidification occurred at high discharge and was caused by dilution of cations, slightly increased DOC, significantly higher NO3, and the sea-salt effect. Depressions in pH were accompanied by increases in inorganic Al. The West Bear catchment responded to the chemical additions with increased export of base cations, Al, SO4, NO3, and

  13. Retrospective Review of Watershed Characteristics and a Framework for Future Research in the Sarasota Bay Watershed, Florida

    USGS Publications Warehouse

    Kish, George R.; Harrison, Arnell S.; Alderson, Mark

    2008-01-01

    The U.S. Geological Survey, in cooperation with the Sarasota Bay Estuary Program conducted a retrospective review of characteristics of the Sarasota Bay watershed in west-central Florida. This report describes watershed characteristics, surface- and ground-water processes, and the environmental setting of the Sarasota Bay watershed. Population growth during the last 50 years is transforming the Sarasota Bay watershed from rural and agriculture to urban and suburban. The transition has resulted in land-use changes that influence surface- and ground-water processes in the watershed. Increased impervious cover decreases recharge to ground water and increases overland runoff and the pollutants carried in the runoff. Soil compaction resulting from agriculture, construction, and recreation activities also decreases recharge to ground water. Conventional approaches to stormwater runoff have involved conveyances and large storage areas. Low-impact development approaches, designed to provide recharge near the precipitation point-of-contact, are being used increasingly in the watershed. Simple pollutant loading models applied to the Sarasota Bay watershed have focused on large-scale processes and pollutant loads determined from empirical values and mean event concentrations. Complex watershed models and more intensive data-collection programs can provide the level of information needed to quantify (1) the effects of lot-scale land practices on runoff, storage, and ground-water recharge, (2) dry and wet season flux of nutrients through atmospheric deposition, (3) changes in partitioning of water and contaminants as urbanization alters predevelopment rainfall-runoff relations, and (4) linkages between watershed models and lot-scale models to evaluate the effect of small-scale changes over the entire Sarasota Bay watershed. As urbanization in the Sarasota Bay watershed continues, focused research on water-resources issues can provide information needed by water

  14. Virgin Islands: Coral Bay Watershed Management (A Former EPA CARE Project)

    EPA Pesticide Factsheets

    The Coral Bay Watershed Management is a recipient of the Level II CARE cooperative agreement to continue and expand its collective efforts to stop erosion, sediment, and storm-water pollution of Coral Bay, improve solid waste management,

  15. Water quality functions of riparian forest buffers in Chesapeake bay watersheds

    USGS Publications Warehouse

    Lowrance, R.; Altier, L.S.; Newbold, J.D.; Schnabel, R.R.; Groffman, P.M.; Denver, J.M.; Correll, D.L.; Gilliam, J.W.; Robinson, J.L.; Brinsfield, R.B.; Staver, K.W.; Lucas, W.; Todd, A.H.

    1997-01-01

    Maryland, Virginia, and Pennsylvania, USA, have agreed to reduce nutrient loadings to Chesapeake Bay by 40% by the year 2000. This requires control of nonpoint sources of nutrients much of which comes from agriculture. Riparian forest buffer systems (RFBS) provide effective control of nonpoint source (NPS) pollution in some types of agricultural watersheds. Control of NPS pollution is dependent on the type of pollutant and the hydrologic connection between pollution sources, the RFBS, and the stream. Water quality improvements are most likely in areas of where most of the excess precipitation moves across, in, or near the root zone of the RFBS. In areas such as the Inner Coastal Plain and Piedmont watersheds with thin soils RFBS should retain 50%-90% of the total loading of nitrate in shallow groundwater sediment in surface runoff and total N in born surface runoff and groundwater. Retention of phosphorus is generally much less. In regions with deeper soils and/or greater regional groundwater recharge (such as parts of the Piedmont and the Valley and Ridge), RFBS water quality improvements are probably much less. The expected levels of pollutant control by RFBS are identified for each of nine physiographic provinces of the Chesapeake Bay Watershed. Issues related to of establishment sustainability, and management are also discussed.

  16. San Francisco and Bay Area, CA, USA

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Although clouds obscure part of the city of San Francisco and the mouth of the Bay (37.5N, 122.0W), many cultural and natural features in the immediate vicinity are obvious. The Bay Bridge which was damaged in the 1989 earthquake, Candlestick Park, San Mateo and Dumbarton Bridges as well as the various colored settling ponds rimming the south end of the Bay, the San Andreas and Calaveras faults and many of the major highways can be seen.

  17. San Francisco and Bay Area, CA, USA

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Although clouds obscure part of the city of San Francisco and the mouth of the Bay (37.5N, 122.0W), many cultural and natural features in the immediate vicinity are obvious. The Bay Bridge which was damaged in the 1989 earthquake, Candlestick Park, San Mateo and Dumbarton Bridges as well as the various colored settling ponds rimming the south end of the Bay, the San Andreas and Calaveras faults and many of the major highways can be seen. Color infrared photography is very useful for haze penetration and greater definition of the imagery as well as vegetation detection, depicted as shades of red.

  18. Chesapeake Bay Watershed - Protecting the Chesapeake Bay and its rivers through science, restoration, and partnership

    USGS Publications Warehouse

    ,

    2012-01-01

    The Chesapeake Bay, the Nation's largest estuary, has been degraded due to the impact of human-population increase, which has doubled since 1950, resulting in degraded water quality, loss of habitat, and declines in populations of biological communities. Since the mid-1980s, the Chesapeake Bay Program (CBP), a multi-agency partnership which includes the Department of Interior (DOI), has worked to restore the Bay ecosystem. The U.S. Geological Survey (USGS) has the critical role of providing unbiased scientific information that is utilized to document and understand ecosystem change to help assess the effectiveness of restoration strategies in the Bay and its watershed. The USGS revised its Chesapeake Bay science plan for 2006-2011 to address the collective needs of the CBP, DOI, and USGS with a mission to provide integrated science for improved understanding and management of the Bay ecosystem. The USGS science themes for this mission are: Causes and consequences of land-use change; Impact of climate change and associated hazards; Factors affecting water quality and quantity; Ability of habitat to support fish and bird populations; and Synthesis and forecasting to improve ecosystem assessment, conservation, and restoration.

  19. U.S. Geological Survey Chesapeake Bay Studies: Scientific Solutions for a Healthy Bay and Watershed

    USGS Publications Warehouse

    Phillips, Scott

    2006-01-01

    Since the mid-1980s, the USGS has been an active partner in the Chesapeake Bay Program (CBP), a multi-agency partnership led by the U.S. Environmental Protection Agency, working to achieve the restoration goals set forth in the Chesapeake 2000 agreement. This agreement established over 100 restoration commitments to be addressed by 2010. In 2005, which was the mid-point of the agreement, there was growing concern at all levels of government and by the public that ecological conditions in the Bay and its watershed had not significantly improved. The slow rate of improvement, coupled with the projected impact of human-population increase in the Bay watershed (fig. 1), implied that many desired ecological conditions will not be achieved by 2010. To address these challenges, the USGS wrote a new science plan for 2006-2011, and is synthesizing key findings to highlight the accomplishments from science activities for 2000-2005.

  20. Microplastic contamination in the San Francisco Bay, California, USA.

    PubMed

    Sutton, Rebecca; Mason, Sherri A; Stanek, Shavonne K; Willis-Norton, Ellen; Wren, Ian F; Box, Carolynn

    2016-08-15

    Despite widespread detection of microplastic pollution in marine environments, data describing microplastic abundance in urban estuaries and microplastic discharge via treated municipal wastewater are limited. This study presents information on abundance, distribution, and composition of microplastic at nine sites in San Francisco Bay, California, USA. Also presented are characterizations of microplastic in final effluent from eight wastewater treatment plants, employing varying treatment technologies, that discharge to the Bay. With an average microplastic abundance of 700,000particles/km(2), Bay surface water appears to have higher microplastic levels than other urban waterbodies sampled in North America. Moreover, treated wastewater from facilities that discharge into the Bay contains considerable microplastic contamination. Facilities employing tertiary filtration did not show lower levels of contamination than those using secondary treatment. As textile-derived fibers were more abundant in wastewater, higher levels of fragments in surface water suggest additional pathways of microplastic pollution, such as stormwater runoff.

  1. Sea Ice, Bristol Bay, Alaska, USA

    NASA Technical Reports Server (NTRS)

    1992-01-01

    This north looking view shows the coast of Alaska, north of the Aleutians, and the eastern margin of the Bering Sea (58.0N, 159.5W). Bristol Bay is apparent in the foreground and Nunivak Island can be seen just below the Earth's horizon, at a distance of about 300 nautical miles. Similar views, photographed during previous missions, when analyzed with these recent views may yield information about regional ice drift and breakup of ice packs.

  2. A Combined Modeling Approach to Evaluate Water Quality Benefits of Riparian Buffers in the Jobos Bay Watershed

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Jobos Bay Watershed, located in south-central Puerto Rico, is a tropical Conservation Effects Assessment Project (CEAP) Special Emphasis Watershed. The purpose of CEAP is to quantify environmental benefits of conservation practices and includes field and watershed modeling. In Jobos Bay, the goa...

  3. 75 FR 78667 - Cooperative Conservation Partnership Initiative-Chesapeake Bay Watershed

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-16

    ...; ] DEPARTMENT OF AGRICULTURE Commodity Credit Corporation Cooperative Conservation Partnership Initiative--Chesapeake Bay Watershed AGENCY: Commodity Credit Corporation and Natural Resources Conservation Service... agreements with the Natural Resources Conservation Service (NRCS) through the Cooperative...

  4. EPA Assessments of the Subwatershed Animal Feeding Operations (AFOs) in the Chesapeake Bay Watershed

    EPA Pesticide Factsheets

    Starting in 2013, EPA is conducting assessments of AFOs within four subwatersheds in the Chesapeake Bay watershed. EPA’s assessments evaluated the compliance with state and federal requirements for reducing nitrogen, phosphorus, and sediment.

  5. Report: Saving the Chesapeake Bay Watershed Requires Better Coordination of Environmental and Agricultural Resources

    EPA Pesticide Factsheets

    Report #2007-P-00004, November 20, 2006. Despite significant efforts to improve water quality in the Chesapeake Bay watershed, excess nutrients and sediment continue to impair the Bay’s water quality.

  6. Monitoring wetland inundation dynamics in response to weather variability in the Chesapeake Bay watershed

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wetlands provide a broad range of ecosystem services, including flood control, water purification, groundwater replenishment, and biodiversity support. The provision of these services, which are especially valued in the Chesapeake Bay Watershed, is largely controlled by varying levels of wetness. ...

  7. Watershed monitoring and modelling and USA regulatory compliance.

    PubMed

    Turner, B G; Boner, M C

    2004-01-01

    The aim of the Columbus program was to implement a comprehensive watershed monitoring-network including water chemistry, aquatic biology and alternative sensors to establish water environment health and methods for determining future restoration progress and early warning for protection of drinking water supplies. The program was implemented to comply with USA regulatory requirements including Total Maximum Daily Load (TMDL) rules of the Clean Water Act (CWA) and Source Water Assessment and Protection (SWAP) rules under the Safe Drinking Water Act (SDWA). The USEPA Office of Research and Development and the Water Environment Research Foundation provided quality assurance oversight. The results obtained demonstrated that significant wet weather data is necessary to establish relationships between land use, water chemistry, aquatic biology and sensor data. These measurements and relationships formed the basis for calibrating the US EPA BASINS Model, prioritizing watershed health and determination of compliance with water quality standards. Conclusions specify priorities of cost-effective drainage system controls that attenuate stormwater flows and capture flushed pollutants. A network of permanent long-term real-time monitoring using combination of continuous sensor measurements, water column sampling and aquatic biology surveys and a regional organization is prescribed to protect drinking water supplies and measure progress towards water quality targets.

  8. Tampa Bay, St. Petersburg, Florida, USA

    NASA Technical Reports Server (NTRS)

    1992-01-01

    This photo of the Tampa Bay, St. Petersburg, Florida (28.0N, 82.5W) is one of a pair (see STS049-97-020) to compare the differences between color film and color infrared film. In the color image above, the scene appears as it would to the human eye. The city of St. Petersburg can be seen even though there is atmospheric haze obscuring the image. Color infrared film filters out the haze and portrays vegetation as shades of red or pink.

  9. Tampa Bay, St. Petersburg, Florida, USA

    NASA Technical Reports Server (NTRS)

    1992-01-01

    This photo of the Tampa Bay, St. Petersburg, Florida (28.0N, 82.5W) is one of a pair (see STS049-92-017) to compare the differences between color film and color infrared film. In the color image above, the scene appears as it would to the human eye. The city of St. Petersburg can be seen even though there is atmospheric haze obscuring the image. Color infrared film filters out the haze and portrays vegetation as shades of red or pink.

  10. Predicting thermal regimes of stream networks across the Chesapeake Bay Watershed: Natural and anthropogenic influences

    EPA Science Inventory

    Thermal regimes are a critical factor in models predicting joint effects of watershed management activities and climate change on fish habitat suitability. We have compiled a database of lotic temperature time series across the Chesapeake Bay Watershed (725 station-year combinat...

  11. Reducing methylmercury accumulation in the food webs of San Francisco Bay and its local watersheds

    SciTech Connect

    Davis, J.A.; Looker, R.E.; Yee, D.; Marvin-Di Pasquale, M.; Austin, C.M.; McKee, L.J.; Greenfield, B.K.; Brodberg, R.; Blum, J.D.

    2012-11-15

    San Francisco Bay (California, USA) and its local watersheds present an interesting case study in estuarine mercury (Hg) contamination. This review focuses on the most promising avenues for attempting to reduce methylmercury (MeHg) contamination in Bay Area aquatic food webs and identifying the scientific information that is most urgently needed to support these efforts. Concern for human exposure to MeHg in the region has led to advisories for consumption of sport fish. Striped bass from the Bay have the highest average Hg concentration measured for this species in USA estuaries, and this degree of contamination has been constant for the past 40 years. Similarly, largemouth bass in some Bay Area reservoirs have some of the highest Hg concentrations observed in the entire US. Bay Area wildlife, particularly birds, face potential impacts to reproduction based on Hg concentrations in the tissues of several Bay species. Source control of Hg is one of the primary possible approaches for reducing MeHg accumulation in Bay Area aquatic food webs. Recent findings (particularly Hg isotope measurements) indicate that the decades-long residence time of particle-associated Hg in the Bay is sufficient to allow significant conversion of even the insoluble forms of Hg into MeHg. Past inputs have been thoroughly mixed throughout this shallow and dynamic estuary. The large pool of Hg already present in the ecosystem dominates the fraction converted to MeHg and accumulating in the food web. Consequently, decreasing external Hg inputs can be expected to reduce MeHg in the food web, but it will likely take many decades to centuries before those reductions are achieved. Extensive efforts to reduce loads from the largest Hg mining source (the historic New Almaden mining district) are underway. Hg is spread widely across the urban landscape, but there are a number of key sources, source areas, and pathways that provide opportunities to capture larger quantities of Hg and reduce loads

  12. Reducing methylmercury accumulation in the food webs of San Francisco Bay and its local watersheds.

    PubMed

    Davis, J A; Looker, R E; Yee, D; Marvin-Di Pasquale, M; Grenier, J L; Austin, C M; McKee, L J; Greenfield, B K; Brodberg, R; Blum, J D

    2012-11-01

    San Francisco Bay (California, USA) and its local watersheds present an interesting case study in estuarine mercury (Hg) contamination. This review focuses on the most promising avenues for attempting to reduce methylmercury (MeHg) contamination in Bay Area aquatic food webs and identifying the scientific information that is most urgently needed to support these efforts. Concern for human exposure to MeHg in the region has led to advisories for consumption of sport fish. Striped bass from the Bay have the highest average Hg concentration measured for this species in USA estuaries, and this degree of contamination has been constant for the past 40 years. Similarly, largemouth bass in some Bay Area reservoirs have some of the highest Hg concentrations observed in the entire US. Bay Area wildlife, particularly birds, face potential impacts to reproduction based on Hg concentrations in the tissues of several Bay species. Source control of Hg is one of the primary possible approaches for reducing MeHg accumulation in Bay Area aquatic food webs. Recent findings (particularly Hg isotope measurements) indicate that the decades-long residence time of particle-associated Hg in the Bay is sufficient to allow significant conversion of even the insoluble forms of Hg into MeHg. Past inputs have been thoroughly mixed throughout this shallow and dynamic estuary. The large pool of Hg already present in the ecosystem dominates the fraction converted to MeHg and accumulating in the food web. Consequently, decreasing external Hg inputs can be expected to reduce MeHg in the food web, but it will likely take many decades to centuries before those reductions are achieved. Extensive efforts to reduce loads from the largest Hg mining source (the historic New Almaden mining district) are underway. Hg is spread widely across the urban landscape, but there are a number of key sources, source areas, and pathways that provide opportunities to capture larger quantities of Hg and reduce loads

  13. Reducing Methylmercury Accumulation in the Food Webs of San Francisco Bay and Its Local Watersheds

    PubMed Central

    Davis, J.A.; Looker, R.E.; Yee, D.; Marvin-DiPasquale, M.; Grenier, J.L.; Austin, C.M.; McKee, L.J.; Greenfield, B.K.; Brodberg, R.; Blum, J.D.

    2013-01-01

    San Francisco Bay (California, USA) and its local watersheds present an interesting case study in estuarine mercury (Hg) contamination. This review focuses on the most promising avenues for attempting to reduce methylmercury (MeHg) contamination in Bay Area aquatic food webs and identifying the scientific information that is most urgently needed to support these efforts. Concern for human exposure to MeHg in the region has led to advisories for consumption of sport fish. Striped bass from the Bay have the highest average Hg concentration measured for this species in USA estuaries, and this degree of contamination has been constant for the past 40 years. Similarly, largemouth bass in some Bay Area reservoirs have some of the highest Hg concentrations observed in the entire US. Bay Area wildlife, particularly birds, face potential impacts to reproduction based on Hg concentrations in the tissues of several Bay species. Source control of Hg is one of the primary possible approaches for reducing MeHg accumulation in Bay Area aquatic food webs. Recent findings (particularly Hg isotope measurements) indicate that the decades-long residence time of particle-associated Hg in the Bay is sufficient to allow significant conversion of even the insoluble forms of Hg into MeHg. Past inputs have been thoroughly mixed throughout this shallow and dynamic estuary. The large pool of Hg already present in the ecosystem dominates the fraction converted to MeHg and accumulating in the food web. Consequently, decreasing external Hg inputs can be expected to reduce MeHg in the food web, but it will likely take many decades to centuries before those reductions are achieved. Extensive efforts to reduce loads from the largest Hg mining source (the historic New Almaden mining district) are underway. Hg is spread widely across the urban landscape, but there are a number of key sources, source areas, and pathways that provide opportunities to capture larger quantities of Hg and reduce loads

  14. The distribution of phosphorus in Popes Creek, VA, and in the Pocomoke River, MD: Two watersheds with different land management practices in the Chesapeake Bay Basin

    USGS Publications Warehouse

    Simon, N.S.; Bricker, O.P.; Newell, W.; McCoy, J.; Morawe, R.

    2005-01-01

    This paper compares phosphorus (P) concentrations in sediments from two watersheds, one with, and one without, intensive animal agriculture. The watersheds are in the coastal plain of the Chesapeake Bay and have similar physiographic characteristics. Agriculture in the Pocomoke River, MD, watershed supplied 2.7 percent of all broiler chickens produced in the USA in 1997. Poultry litter is an abundant, local source of manure for crops. Broiler chickens are not produced in the Popes Creek, VA, watershed and poultry manure is, therefore, not a major source of fertilizer. The largest concentrations of P in sediment samples are found in floodplain and main-stem bottom sediment in both watersheds. Concentrations of total P and P extracted with 1N HCl are significantly larger in main-stem bottom sediments from the Pocomoke River than in main-stem bottom sediments from Popes Creek. Larger concentrations of P are associated with what are potentially redox sensitive iron oxyhydroxides in sediment samples from the Pocomoke River watershed than are associated with what are potentially redox sensitive iron oxyhydroxides in sediment samples from the Popes Creek watershed. Data for P and iron (Fe) concentrations in sediments from the Popes Creek watershed provide a numerical framework (baseline) with which to compare P and Fe concentrations in sediment from the Pocomoke River watershed. ?? Springer 2005.

  15. 75 FR 27552 - Guidance for Federal Land Management in the Chesapeake Bay Watershed

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-17

    ... water pollution'' that are appropriate to restore and protect the Chesapeake Bay. Assuming that all... the Bay and its watershed with the most effective tools and practices available to reduce water pollution from a variety of nonpoint sources, including agricultural lands, urban and suburban...

  16. Managing manure for sustainable livestock production in the Chesapeake Bay Watershed

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Manure presents one of the greatest challenges to livestock operations in the Chesapeake Bay Watershed. The Chesapeake Bay is threatened by excessive nutrient loadings and, according to the U.S. Environmental Protection Agency, manure is the source of 18% of the nitrogen and 27% of the phosphorus en...

  17. A system dynamics model for the environmental management of the Sepetiba Bay Watershed, Brazil.

    PubMed

    Leal Neto, Alexandre de C; Legey, Luiz F L; González-Araya, Marcela Cecilia; Jablonski, Silvio

    2006-11-01

    In the recent past, the Sepetiba Bay watershed, located in the Rio de Janeiro State, Brazil has experienced rapid industrial development and population growth, as well as an increase in water pollution and environmental degradation. To analyze the complex interrelationships among the agents affecting the Sepetibza Bay environment, a system dynamics model was developed. The model builds on extensive studies conducted for the watershed, and simulates different hypotheses of economic growth and of demographic expansion. Thus, it can be used as a decision support tool for the identification of investment priorities and policy analyses under various scenarios. In order to provide a comprehensive approach to the environmental management of the Sepetiba Bay watershed, the model had to consider only the most relevant aspects of the behavior and the key interactions among agents operating in the watershed. In this article, the model's structure is presented together with some of its main results.

  18. Watershed nutrient inputs, phytoplankton accumulation, and C stocks in Chesapeake Bay

    NASA Astrophysics Data System (ADS)

    Fisher, T. R.; Boynton, W. R.; Hagy, J. D.

    2002-12-01

    Inputs of N and P to Chesapeake Bay have been enhanced by anthropogenic activities. Fertilizers, urbanization, N emissions, and industrial effluents contribute to point and diffuse sources currently 2-7X higher for P and 5-20X higher for N than those from undisturbed watersheds. Enhanced nutrient inputs cause phytoplankton blooms which obscure visibility, eliminate submerged grasses, and influence the distribution of C within the Bay. Accumulations of dissolved organic and particulate organic C lead to enhanced microbial respiration in isolated bottom waters, and dissolved oxygen is seasonally reduced to trace levels during summer. Cultural eutrophication is not unique to Chesapeake Bay. Although some estuaries such as the Delaware, Hudson, and San Francisco Bay also have high anthropogenic inputs, these estuaries have much shorter residence times, and much of the N and P may be exported to the coastal ocean. However, in Chesapeake Bay, with residence times >2 months, internal processing of watershed inputs results in local algal blooms within the estuary. Watershed restoration strategies for Chesapeake watersheds have had limited success to date. Groundwaters are enriched with nitrate, and the long residence times of groundwaters mean slow responses to watershed improvements. The few successes in the Chesapeake have been associated with point source reductions, although continued human population growth can easily override restoration efforts. Widespread improvement in water quality has yet to occur, but the limited successes show that the Bay responds to load changes.

  19. Temporal and spatial patterns in tumour prevalence in brown bullhead Ameiurus nebulosus (Lesueur) in the tidal Potomac River watershed (USA).

    PubMed

    Pinkney, A E; Harshbarger, J C; Rutter, M A

    2014-10-01

    For two decades, fish tumour surveys have been used to monitor habitat quality in the Chesapeake Bay (USA) watershed. Tributaries with sediments contaminated with polynuclear aromatic hydrocarbons (PAHs), known to cause liver neoplasia, were frequently targeted. Here, we compare surveys in brown bullhead Ameiurus nebulosus conducted in 2009-2011 in the tidal Potomac River watershed (including the Anacostia River) with previous surveys. Using logistic regression, we identified length and sex as covariates for liver and skin tumours. We reported a statistically significant decrease in liver tumour probabilities for standardized 280 mm Anacostia bullheads between the 1996 and 2001 samplings (merged collections: female-77.5%, male-43.0%) and 2009-2011 (female-42.2%, male-13.6%). However, liver tumour prevalence in bullheads from the Anacostia, Potomac River (Washington, DC) and Piscataway Creek (17 km downriver) was significantly higher than that for Chesapeake Bay watershed reference locations. The causes of skin tumours in bullheads are uncertain, requiring further research. The similar liver tumour prevalence in these three locations suggests that the problem is regional rather than restricted to the Anacostia. To monitor habitat quality and the success of pollution control actions, we recommend conducting tumour surveys on a 5-year cycle coordinated with sediment chemistry analyses.

  20. Goddard DEVELOP Students: Using NASA Remote Sensing Technology to Study the Chesapeake Bay Watershed

    NASA Technical Reports Server (NTRS)

    Moore, Rachel

    2011-01-01

    The DEVELOP National Program is an Earth Science research internship, operating under NASA s Applied Sciences Program. Each spring, summer, and fall, DEVELOP interns form teams to investigate Earth Science related issues. Since the Fall of 2003, Goddard Space Flight Center (GSFC) has been home to one of 10 national DEVELOP teams. In past terms, students completed a variety of projects related to the Applied Sciences Applications of National Priority, such as Public Health, Natural Disasters, Water Resources, and Ecological Forecasting. These projects have focused on areas all over the world, including the United States, Africa, and Asia. Recently, Goddard DEVELOP students have turned their attention to a local environment, the Chesapeake Bay Watershed. The Chesapeake Bay Watershed is a complex and diverse ecosystem, spanning approximately 64,000 square miles. The watershed encompasses parts of six states: Delaware, Maryland, New York, Pennsylvania, Virginia, and West Virginia, as well as the District of Columbia. The Bay itself is the biggest estuary in the United States, with over 100,000 tributaries feeding into it. The ratio of fresh water to salt water varies throughout the Bay, allowing for a variety of habitats. The Bay s wetlands, marshes, forests, reefs, and rivers support more than 3,600 plant and animal species, including birds, mammals, reptiles, amphibians, fish, and crabs. The Bay is also commercially significant. It is ranked third in the nation in fishery catch, and supplies approximately 500 million pounds of seafood annually. In addition to its abundant flora and fauna, the Chesapeake Bay watershed is home to approximately 16.6 million people, who live and work throughout the watershed, and who use its diverse resources for recreational purposes. Over the past several decades, the population throughout the watershed has increased rapidly, resulting in land use changes, and ultimately decreasing the health of the Chesapeake Bay Watershed. Over the

  1. Contaminant exposure of birds nesting in Green Bay, Wisconsin, USA

    USGS Publications Warehouse

    Custer, Thomas W.; Dummer, Paul M.; Custer, Christine M.; Franson, J. Christian; Jones, Michael

    2014-01-01

    In earlier studies, elevated concentrations of polychlorinated biphenyl (PCB) and p,p'-dichlorodiphenyldichloroethylene (DDE) were reported in double-crested cormorant (Phalacrocorax auritus) eggs and tree swallow (Tachycineta bicolor) eggs and nestlings collected from lower Green Bay (WI, USA) in 1994 and 1995 and black-crowned night-heron (Nycticorax nycticorax) eggs collected in 1991. Comparable samples collected in 2010 and 2011 indicated that concentrations of PCBs were 35%, 62%, 70%, and 88% lower than in the early 1990s in tree swallow eggs, tree swallow nestlings, double-crested cormorant eggs, and black-crowned night-heron eggs, respectively; concentrations of DDE were 47%, 43%, 51%, and 80% lower, respectively. These declines are consistent with regional contaminant trends in other species. Concentrations of PCBs were higher in herring gull (Larus argentatus) than in black-crowned night-heron eggs collected from Green Bay in 2010; PCB concentrations in double-crested cormorant and tree swallow eggs were intermediate. The estimated toxicity of the PCB mixture in eggs of the insectivorous tree swallow was the equal to or greater than toxicity in the 3 piscivorous bird species. A multivariate analysis indicated that the composition percentage of lower-numbered PCB congeners was greater in eggs of the insectivorous tree swallow than in eggs of the 3 piscivorous species nesting in Green Bay. Dioxin and furan concentrations and the toxicity of these chemicals were also higher in tree swallows than these other waterbird species nesting in Green Bay.

  2. Contaminant exposure of birds nesting in Green Bay, Wisconsin, USA.

    PubMed

    Custer, Thomas W; Dummer, Paul M; Custer, Christine M; Franson, J Christian; Jones, Michael

    2014-08-01

    In earlier studies, elevated concentrations of polychlorinated biphenyl (PCB) and p,p'-dichlorodiphenyldichloroethylene (DDE) were reported in double-crested cormorant (Phalacrocorax auritus) eggs and tree swallow (Tachycineta bicolor) eggs and nestlings collected from lower Green Bay (WI, USA) in 1994 and 1995 and black-crowned night-heron (Nycticorax nycticorax) eggs collected in 1991. Comparable samples collected in 2010 and 2011 indicated that concentrations of PCBs were 35%, 62%, 70%, and 88% lower than in the early 1990s in tree swallow eggs, tree swallow nestlings, double-crested cormorant eggs, and black-crowned night-heron eggs, respectively; concentrations of DDE were 47%, 43%, 51%, and 80% lower, respectively. These declines are consistent with regional contaminant trends in other species. Concentrations of PCBs were higher in herring gull (Larus argentatus) than in black-crowned night-heron eggs collected from Green Bay in 2010; PCB concentrations in double-crested cormorant and tree swallow eggs were intermediate. The estimated toxicity of the PCB mixture in eggs of the insectivorous tree swallow was the equal to or greater than toxicity in the 3 piscivorous bird species. A multivariate analysis indicated that the composition percentage of lower-numbered PCB congeners was greater in eggs of the insectivorous tree swallow than in eggs of the 3 piscivorous species nesting in Green Bay. Dioxin and furan concentrations and the toxicity of these chemicals were also higher in tree swallows than these other waterbird species nesting in Green Bay.

  3. Comparison of sediment supply to San Francisco Bay from watersheds draining the Bay Area and the Central Valley of California

    USGS Publications Warehouse

    McKee, L.J.; Lewicki, M.; Schoellhamer, D.H.; Ganju, N.K.

    2013-01-01

    Quantifying suspended sediment loads is important for managing the world's estuaries in the context of navigation, pollutant transport, wetland restoration, and coastal erosion. To address these needs, a comprehensive analysis was completed on sediment supply to San Francisco Bay from fluvial sources. Suspended sediment, optical backscatter, velocity data near the head of the estuary, and discharge data obtained from the output of a water balance model were used to generate continuous suspended sediment concentration records and compute loads to the Bay from the large Central Valley watershed. Sediment loads from small tributary watersheds around the Bay were determined using 235 station-years of suspended sediment data from 38 watershed locations, regression analysis, and simple modeling. Over 16 years, net annual suspended sediment load to the head of the estuary from its 154,000 km2 Central Valley watershed varied from 0.13 to 2.58 (mean = 0.89) million metric t of suspended sediment, or an average yield of 11 metric t/km2/yr. Small tributaries, totaling 8145 km2, in the nine-county Bay Area discharged between 0.081 and 4.27 (mean = 1.39) million metric t with a mean yield of 212 metric t/km2/yr. The results indicate that the hundreds of urbanized and tectonically active tributaries adjacent to the Bay, which together account for just 5% of the total watershed area draining to the Bay and provide just 7% of the annual average fluvial flow, supply 61% of the suspended sediment. The small tributary loads are more variable (53-fold between years compared to 21-fold for the inland Central Valley rivers) and dominated fluvial sediment supply to the Bay during 10 out of 16 yr. If San Francisco Bay is typical of other estuaries in active tectonic or climatically variable coastal regimes, managers responsible for water quality, dredging and reusing sediment accumulating in shipping channels, or restoring wetlands in the world's estuaries may need to more carefully

  4. Revised method and outcomes for estimating soil phosphorus losses from agricultural land in the Chesapeake Bay watershed model

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Current restoration efforts for the Chesapeake Bay watershed mandate a timeline for reducing the load of nutrients and sediment to receiving waters. The Chesapeake Bay Watershed Model (WSM) has been used for two decades to simulate hydrology and nutrient and sediment transport; however, spatial limi...

  5. A summary report of sediment processes in Chesapeake Bay and watershed

    USGS Publications Warehouse

    Langland, Michael; Cronin, Thomas

    2003-01-01

    The Chesapeake Bay, the Nation's largest estuary, has been degraded because of diminished water quality, loss of habitat, and over-harvesting of living resources. Consequently, the bay was listed as an impaired water body due to excess nutrients and sediment. The Chesapeake Bay Program (CBP), a multi-jurisdictional partnership, completed an agreement called ?Chesapeake 2000? that revises and establishes new restoration goals through 2010 in the bay and its watershed. The goal of this commitment is the removal of the bay from the list of impaired waterbodies by the year 2010. The CBP is committed to developing sediment and nutrient allocations for major basins within the bay watershed and to the process of examining new and innovative management plans in the estuary itself and along the coastal zones of the bay. However, additional information is required on the sources, transport, and deposition of sediment that affect water clarity. Because the information and data on sediment processes in the bay were not readily accessible to the CBP or to state, and local managers, a Sediment Workgroup (SWGP) was created in 2001. The primary objective of this report, therefore, is to provide a review of the literature on the sources, transport, and delivery of sediment in Chesapeake Bay and its watershed with discussion of potential implications for various management alternatives. The authors of the report have extracted, discussed, and summarized the important aspects of sediment and sedimentation that are most relevant to the CBP and other sediment related-issues with which resources managers are involved. This report summarizes the most relevant studies concerning sediment sources, transport and deposition in the watershed and estuary, sediments and relation to water clarity, and provides an extensive list of references for those wanting more information.

  6. Ecosystem responses to long-term nutrient management in an urban estuary: Tampa Bay, Florida, USA

    NASA Astrophysics Data System (ADS)

    Greening, H.; Janicki, A.; Sherwood, E. T.; Pribble, R.; Johansson, J. O. R.

    2014-12-01

    In subtropical Tampa Bay, Florida, USA, we evaluated restoration trajectories before and after nutrient management strategies were implemented using long-term trends in nutrient loading, water quality, primary production, and seagrass extent. Following citizen demands for action, reduction in wastewater nutrient loading of approximately 90% in the late 1970s lowered external total nitrogen (TN) loading by more than 50% within three years. Continuing nutrient management actions from public and private sectors were associated with a steadily declining TN load rate and with concomitant reduction in chlorophyll-a concentrations and ambient nutrient concentrations since the mid-1980s, despite an increase of more than 1 M people living within the Tampa Bay metropolitan area. Water quality (chlorophyll-a concentration, water clarity as indicated by Secchi disk depth, total nitrogen concentration and dissolved oxygen) and seagrass coverage are approaching conditions observed in the 1950s, before the large increases in human population in the watershed. Following recovery from an extreme weather event in 1997-1998, water clarity increased significantly and seagrass is expanding at a rate significantly different than before the event, suggesting a feedback mechanism as observed in other systems. Key elements supporting the nutrient management strategy and concomitant ecosystem recovery in Tampa Bay include: 1) active community involvement, including agreement about quantifiable restoration goals; 2) regulatory and voluntary reduction in nutrient loadings from point, atmospheric, and nonpoint sources; 3) long-term water quality and seagrass extent monitoring; and 4) a commitment from public and private sectors to work together to attain restoration goals. A shift from a turbid, phytoplankton-based system to a clear water, seagrass-based system that began in the 1980s following comprehensive nutrient loading reductions has resulted in a present-day Tampa Bay which looks and

  7. Microplastics in four estuarine rivers in the Chesapeake Bay, U.S.A.

    PubMed

    Yonkos, Lance T; Friedel, Elizabeth A; Perez-Reyes, Ana C; Ghosal, Sutapa; Arthur, Courtney D

    2014-12-16

    Once believed to degrade into simple compounds, increasing evidence suggests plastics entering the environment are mechanically, photochemically, and/or biologically degraded to the extent that they become imperceptible to the naked eye yet are not significantly reduced in total mass. Thus, more and smaller plastics particles, termed microplastics, reside in the environment and are now a contaminant category of concern. The current study tested the hypotheses that microplastics concentration would be higher in proximity to urban sources, and vary temporally in response to weather phenomena such as storm events. Triplicate surface water samples were collected approximately monthly between July and December 2011 from four estuarine tributaries within the Chesapeake Bay, U.S.A. using a manta net to capture appropriately sized microplastics (operationally defined as 0.3-5.0 mm). Selected sites have watersheds with broadly divergent land use characteristics (e.g., proportion urban/suburban, agricultural and/or forested) and wide ranging population densities. Microplastics were found in all but one of 60 samples, with concentrations ranging over 3 orders of magnitude (<1.0 to >560 g/km(2)). Concentrations demonstrated statistically significant positive correlations with population density and proportion of urban/suburban development within watersheds. The greatest microplastics concentrations also occurred at three of four sites shortly after major rain events.

  8. Different seasonality of nitrate export from an agricultural watershed and an urbanized watershed in Midwestern USA

    NASA Astrophysics Data System (ADS)

    Tian, S.; Youssef, M. A.; Richards, R. P.; Liu, J.; Baker, D. B.; Liu, Y.

    2016-10-01

    Land use/land cover is a critical factor affecting temporal dynamics of nitrate export from watersheds. Based on a long-term (>30 years) water quality monitoring program in the Western Lake Erie area, United States, this study compared seasonal variation of nitrate export from an agricultural watershed and an urbanized watershed. A seasonality index was adapted to quantitatively characterize seasonal variation of nitrate export from the two watersheds. Results showed that monthly nitrate concentrations from the two watersheds exhibited different seasonal variation. Seasonality index of monthly nitrate loading for the agricultural watershed is approximately 3 times of that from the urbanized watershed and the difference is statistically significant (p < 0.0001). Meanwhile, calculated historical seasonality indexes of monthly nitrate loading for both watersheds exhibited significant (p < 0.05) decreasing trends according to the non-seasonal Mann-Kendall test. The identified differences in seasonal nitrate export from the two watersheds were mainly attributed to their distinct nitrogen sources, physical and biogeochemical settings. The declining seasonality index of monthly nitrate loading from the agricultural watershed could be partially caused by historical climate change in the study region, especially increased temperature during winter. Urbanization could be one key factor contributing to the declining seasonality index of monthly nitrate loading from the urbanized watershed. Information derived from this study have practical implications for developing proper management practices to mitigate nitrate pollution in Midwestern United States.

  9. Late-Holocene climate andecosystem history from Chesapeake Bay sediment cores, USA

    USGS Publications Warehouse

    Willard, D.A.; Cronin, T. M.; Verardo, S.

    2003-01-01

    Palaeoclimate records from late-Holocene sediments in Chesapeake Bay, the largest estuary in the USA, provide evidence that both decadal to centennial climate variability and European colonization had severe impacts on the watershed and estuary. Using pollen and dinoflagellate cysts as proxies for mid-Atlantic regional precipitation, estuarine salinity and dissolved oxygen (DO) during the last 2300 years, we identified four dry intervals, centred on AD 50 (P1/D1), AD 1000 (P2/D2), AD 1400 (P3) and AD 1600 (P4). Two centennial-scale events, P1/D1 and P2/D2, altered forest composition and led to increased salinity and DO levels in the estuary. Intervals P3 and P4 lasted several decades, leading to decreased production of pine pollen. Periods of dry mid-Atlantic climate correspond to 'megadroughts' identified from tree-ring records in the southeastern and central USA. The observed mid-Atlantic climate variability may be explained by changes in atmospheric circulation resulting in longer-term, perhaps amplified, intervals of meridional flow. After European colonization in the early seventeenth century, forest clearance for agriculture, timber and urbanization altered estuarine water quality, with dinoflagellate assemblages indicating reduced DO and increased turbidity.

  10. Intensive survey of the bay creek watershed, July 1992

    SciTech Connect

    Short, M.B.; Kelly, T.G.; Hefley, J.E.

    1995-05-01

    During July 1992, the Illinois Environmental Protection Agency conducted an intensive survey of the Bay Creek basin, a fifth order tributary in the Mississippi River North Central Basin. Bay Creek drains approximately 176.4 square miles primarily in Pike and a small portion of Calhoun counties. Four stations were sampled on the Bay Creek main stem and one on Honey Creek. The survey focused on macroinvertebrate communities, fish populations, instream habitat, fish tissue, sediment and water chemistry, and land use as well as a review of ambient water quality data from IEPA station KCA-01 near Nebo, Illinois, as tools to document the biological and chemical status of Bay Creek.

  11. EVALUATING THE INTEGRITY OF SALT MARSHES IN NARRAGANSETT BAY SUB-ESTUARIES USING A WATERSHED APPROACH

    EPA Science Inventory

    A watershed approach to examine measures of structure and function in salt marshes of similar geomorphology and hydrology in Narragansett Bay is being used to develop a reference system for evaluating salt marsh integrity. We describe integrity as the capability of a salt marsh t...

  12. Linking Decisions to Stakeholder Values in the Guanica Bay Watershed, Puerto Rico

    EPA Science Inventory

    This presentation lays the foundation for the session by introducing the Structured Decision-Making (SDM) approach that is being used by the Environmental Protection Agency (EPA) in the Guánica Bay watershed of southwestern Puerto Rico. EPA is working with other agencies i...

  13. 77 FR 33194 - Proposed Information Collection; Comment Request; Bay Watershed Education and Training Program...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-05

    ... Watershed Education and Training Program National Evaluation System AGENCY: National Oceanic and Atmospheric... Office of Education, (202) 482-6797 or Bronwen.Rice@noaa.gov . SUPPLEMENTARY INFORMATION: I. Abstract This request is for a new information collection. The NOAA Office of Education's Bay...

  14. Conservation Effects Assessment on the Jobos Bay Puerto Rico Coastal Watershed

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Conservation Effects Assessment Project (CEAP) began in 2003 as a multi-agency effort to quantify the environmental benefits of conservation practices used by private landowners participating in selected U.S. Department of Agriculture (USDA) conservation programs. The Jobos Bay Watershed in Sou...

  15. Carbonate system biogeochemistry in a subterranean estuary - Waquoit Bay, USA

    NASA Astrophysics Data System (ADS)

    Liu, Qian; Charette, Matthew A.; Breier, Crystaline F.; Henderson, Paul B.; McCorkle, Daniel C.; Martin, William; Dai, Minhan

    2017-04-01

    Quantifying carbon fluxes associated with submarine groundwater discharge (SGD) remains challenging due to the complex biogeochemistry of the carbonate system in the subterranean estuary (STE). Here we conducted time series measurements of total alkalinity (TAlk) and dissolved inorganic carbon (DIC) in a well-studied coastal aquifer (Waquoit Bay, Massachusetts, USA). Groundwater samples were collected monthly from May 2009 to June 2010 across the freshwater-saltwater mixing zone of the Waquoit Bay (WB) STE. The concentrations of both TAlk and DIC in zero-salinity groundwater were variable, but were lower than those in the bay water (S ∼ 28). DIC underwent slightly non-conservative mixing between low and intermediate salinities while there was an apparent additional DIC source at high salinity (>20) in all seasons. TAlk concentrations exhibited even stronger variations, with evidence of both production and consumption in high salinity zones, and consistent TAlk consumption at intermediate salinity in summer and fall (June-December, 2009). The increases in DIC and TAlk at high salinity were attributed to aerobic respiration and denitrification in WB sediments during bay water recharge of the STE. We infer that the loss of TAlk at intermediate salinity reflects H+ production as reduced compounds (e.g. Fe2+) are oxidized within the STE. In terms of impacts on surface water inorganic carbon budgets, the SGD-derived DIC flux was mainly controlled by seasonal changes in SGD while a combination of TAlk concentration variability and SGD drove the TAlk flux. SGD-derived DIC, aqueous CO2, and H+ fluxes to the bay were ∼40-50% higher in summer vs. in winter, a result of enhanced marine groundwater flux and significant TAlk removal (proton addition) during periods of high seawater intrusion. Furthermore, the SGD-derived DIC flux was consistently greater than TAlk flux regardless of season, indicating that SGD serves to reduce the CO2 buffering capacity of surface water. Our

  16. Inventorying and monitoring wetland condition and restoration potential on a watershed basis with examples from spring creek watershed, Pennsylvania, USA.

    PubMed

    Brooks, Robert P; Wardrop, Denice Heller; Cole, Charles Andrew

    2006-10-01

    We developed an approach for inventorying wetland resources, assessing their condition, and determining restoration potential in a watershed context. This article outlines how this approach can be developed into a Wetland Monitoring Matrix (WMM) that can help resource management agencies make regulatory and nonregulatory decisions. The WMM can be embedded in a standard planning process (Wetlands, Wildlife, and Watershed Assessment Techniques for Evaluation and Restoration, or W3ATER) involving the setting of objectives, assessing the condition of the resource, prioritizing watersheds or sites, implementing projects, and evaluating progress. To that process we have added the concepts of reference, hydrogeomorphic (HGM) classification, and prioritization for protection and restoration by triage or adaptive management. Three levels of effort are possible, increasing in detail and diagnostic reliability as data collection shifts from remote sensing to intensive sampling on the ground. Of key importance is the use of a consistent set of monitoring protocols for conducting condition assessments, designing restoration and creation projects, and evaluating the performance of mitigation projects; the same variables are measured regardless of the intended use of the data. This approach can be tailored to any region by establishing a reference set of wetlands organized by HGM subclasses, prioritizing watersheds and individual wetlands, and implementing consistent monitoring protocols. Application of the approach is illustrated with examples from wetlands and streams of the Spring Creek Watershed in central Pennsylvania, USA.

  17. Understanding nutrients in the Chesapeake Bay watershed and implications for management and restoration: the Eastern Shore

    USGS Publications Warehouse

    Ator, Scott W.; Denver, Judith M.

    2015-03-12

    The Eastern Shore includes only a small part of the Chesapeake Bay watershed, but contributes disproportionately large loads of the excess nitrogen and phosphorus that have contributed to ecological and economic degradation of the bay in recent decades. Chesapeake Bay is the largest estuary in the United States and a vital ecological and economic resource. The bay and its tributaries have been degraded in recent decades by excessive nitrogen and phosphorus in the water column, however, which cause harmful algal blooms and decreased water clarity, submerged aquatic vegetation, and dissolved oxygen. The disproportionately large nitrogen and phosphorus yields from the Eastern Shore to Chesapeake Bay are attributable to human land-use practices as well as natural hydrogeologic and soil conditions. Applications of nitrogen and phosphorus compounds to the Eastern Shore from human activities are intensive. More than 90 percent of nitrogen and phosphorus reaching the land in the Eastern Shore is applied as part of inorganic fertilizers or manure, or (for nitrogen) fixed directly from the atmosphere in cropland. Also, hydrogeologic and soil conditions promote the movement of these compounds from application areas on the landscape to groundwater and (or) surface waters, and the proximity of much of the Eastern Shore to tidal waters limits opportunities for natural removal of these compounds in the landscape. The Eastern Shore only includes 7 percent of the Chesapeake Bay watershed, but receives nearly twice as much nitrogen and phosphorus applications (per area) as the remainder of the watershed and yields greater nitrogen and phosphorus, on average, to the bay. Nitrogen and phosphorus commonly occur in streams at concentrations that may adversely affect aquatic ecosystems and have increased in recent decades.

  18. Current Erosion and Sediment Research Concerns in Agricultural Watersheds in the USA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil erosion research programs in the USA began in earnest following events of the 1933 Dust Bowl. During the early years from the 1930s-1960s, the focus was on determining the scale and severity of this problem by making measurements on plots, field-size areas, and small agricultural watersheds. Th...

  19. USING BROAD-SCALE METRICS TO DEVELOP INDICATORS OF WATERSHED VULNERABILITY IN THE OZARK MOUNTAINS (USA)

    EPA Science Inventory

    Multiple broad-scale landscape metrics were tested as potential indicators of total phosphorus (TP) concentration, total ammonia (TA) concentration, and Escherichia coli (E. coli) bacteria count, among 244 sub-watersheds in the Ozark Mountains (USA). Indicator models were develop...

  20. Sources, Transport, and Storage of Sediment at Selected Sites in the Chesapeake Bay Watershed

    USGS Publications Warehouse

    Gellis, Allen C.; Hupp, Cliff R.; Pavich, Milan J.; Landwehr, Jurate M.; Banks, William S.L.; Hubbard, Bernard E.; Langland, Michael J.; Ritchie, Jerry C.; Reuter, Joanna M.

    2009-01-01

    The Chesapeake Bay Watershed covers 165,800 square kilometers and is supplied with water and sediment from five major physiographic provinces: Appalachian Plateau, Blue Ridge, Coastal Plain, Piedmont, and the Valley and Ridge. Suspended-sediment loads measured in the Chesapeake Bay Watershed showed that the Piedmont Physiographic Province has the highest rates of modern (20th Century) sediment yields, measured at U.S. Geological Survey streamflow-gaging stations, and the lowest rates of background or geologic rates of erosion (~10,000 years) measured with in situ beryllium-10. In the agricultural and urbanizing Little Conestoga Creek Watershed, a Piedmont watershed, sources of sediment using the 'sediment-fingerprinting' approach showed that streambanks were the most important source (63 percent), followed by cropland (37 percent). Cesium-137 inventories, which quantify erosion rates over a 40-year period, showed average cropland erosion of 19.39 megagrams per hectare per year in the Little Conestoga Creek Watershed. If this erosion rate is extrapolated to the 13 percent of the watershed that is in cropland, then cropland could contribute almost four times the measured suspended-sediment load transported out of the watershed (27,600 megagrams per hectare per year), indicating that much of the eroded sediment is being deposited in channel and upland storage. The Piedmont has had centuries of land-use change, from forest to agriculture, to suburban and urban areas, and in some areas, back to forest. These land-use changes mobilized a large percentage of sediment that was deposited in upland and channel storage, and behind thousands of mill dams. The effects of these land-use changes on erosion and sediment transport are still being observed today as stored sediment in streambanks is a source of sediment. Cropland is also an important source of sediment. The Coastal Plain Physiographic Province has had the lowest sediment yields in the 20th Century and with sandy

  1. Cytochrome P450 and organochlorine contaminants in black-crowned night-herons from the Chesapeake Bay region, USA

    USGS Publications Warehouse

    Rattner, B.A.; Melancon, M.J.; Rice, C.P.; Riley, W.; Eisemann, J.; Hines, R.K.

    1997-01-01

    Black-crowned night-heron (Nycticorax nycticorax) offspring were collected from a relatively uncontaminated coastal reference site (next to Chincoteague National Wildlife Refuge, VA, USA) and two sites in the Chesapeake Bay watershed (Baltimore Harbor, MD and Rock Creek Park, Washington, D.C., USA). Hepatic microsomal activities of benzyloxyresorufin-O-dealkylase and ethoxyresorufin-O-dealkylase were significantly elevated (up to sixfold and ninefold induction, respectively) in pipping embryos from the Baltimore Harbor colony compared to the reference site, whereas values in embryos from the Rock Creek Park colony were intermediate. Concentrations of organochlorine pesticides and metabolites in pipping embryos from both sites in the Chesapeake watershed were greater than at the reference site, but below known threshold for reproductive impairment. However, concentrations of 10 arylhydrocarbon-receptor active PCB congeners and estimated toxic equivalents were up to 37-fold greater in embryos collected from these two sites in the Chesapeake Bay region, with values for toxic congeners 77 and 126 exceeding those observed in pipping heron embryos from the Great Lakes. Monooxygenase activity of pipping embryos was frequently associated with concentrations of organochlorine contaminants and toxic equivalents (r = 0.30 to 0.59), providing further evidence of the value of cytochrome P450 as a biomarker of organic contaminant exposure. Organochlorine contaminant levels were greater in 10-d-old nestlings from Baltimore Harbor than the reference site, but had no apparent effect on monooxygenase activity or growth. These findings demonstrate induction of cytochrome P450 in pipping black-crowned night-heron embryos in the Chesapeake Bay region, probably by exposure to PCB congeners of local origin, and the accumulation of organochlorine pesticides and metabolites in nestling herons from Baltimore Harbor.

  2. Quantitative Models for the Narragansett Bay Estuary, Rhode Island/Massachusetts, USA

    EPA Science Inventory

    Multiple drivers, including nutrient loading and climate change, affect the Narragansett Bay ecosystem in Rhode Island/Massachusetts, USA. Managers are interested in understanding the timing and magnitude of these effects, and ecosystem responses to restoration actions. To provid...

  3. Digital data used to relate nutrient input to water quality in the Chesapeake Bay watershed

    USGS Publications Warehouse

    Brakebill, John W.; Preston, Stephen D.; Martucci, Sarah K.

    2001-01-01

    Digital data sets compiled by the U.S. Geological Survey were used as input for a collection of Spatially Referenced Regressions On Watershed (SPARROW) attributes for the Chesapeake Bay region including parts of Delaware, Maryland, New York, Pennsylvania, Virginia, West Virginia, and the District of Columbia. These regressions use a nonlinear statistical approach to relate nutrient sources and land-surface characteristics to nutrient loads of streams throughout the Chesapeake Bay watershed. A digital segmented-watershed network serves as the primary framework for spatially referencing nutrient-source and land-surface characteristic data within a geographic information system. Flow direction and flow accumulation generated from a 30-meter cell-size Digital Elevation Model and attributes from 1:500,000-scale stream data were used to generate stream and watershed networks. Spatial data sets representing nutrient inputs of total nitrogen and total phosphorus from the early 1990's were created and compiled from numerous sources. Data include atmospheric deposition, septic systems, point-source locations, land use, land cover, and agricultural sources such as commercial fertilizer and manure. Some land-surface characteristic data sets representing factors that affect the transport of nutrients also were compiled. Data sets include land use, land cover, average-annual precipitation and temperature, slope, hydrogeomorphic regions, and soil permeability. Nutrient-input and land-surface characteristic data sets merged with the segmented-watershed network provide the spatial detail by watershed segment required by SPARROW. Stream-nutrient load estimates for 132 sampling sites representing the early 1990's (103 for total nitrogen and 121 for total phosphorus) serve as the dependent variables for the regressions. These estimates were used to calibrate models of total nitrogen and total phosphorus depicting 1992 land-surface conditions. Examples of model predictions consist of

  4. Collection and analysis of remotely sensed data from the Rhode River Estuary Watershed. [ecological parameters of Chesapeake Bay

    NASA Technical Reports Server (NTRS)

    Jenkins, D. W.

    1972-01-01

    NASA chose the watershed of Rhode River, a small sub-estuary of the Bay, as a representative test area for intensive studies of remote sensing, the results of which could be extrapolated to other estuarine watersheds around the Bay. A broad program of ecological research was already underway within the watershed, conducted by the Smithsonian Institution's Chesapeake Bay Center for Environmental Studies (CBCES) and cooperating universities. This research program offered a unique opportunity to explore potential applications for remote sensing techniques. This led to a joint NASA-CBCES project with two basic objectives: to evaluate remote sensing data for the interpretation of ecological parameters, and to provide essential data for ongoing research at the CBCES. A third objective, dependent upon realization of the first two, was to extrapolate photointerpretive expertise gained at the Rhode River watershed to other portions of the Chesapeake Bay.

  5. Factors affecting nutrient trends in major rivers of the Chesapeake Bay Watershed

    USGS Publications Warehouse

    Sprague, Lori A.; Langland, M.J.; Yochum, S.E.; Edwards, R.E.; Blomquist, J.D.; Phillips, S.W.; Shenk, G.W.; Preston, S.D.

    2000-01-01

    Trends in nutrient loads and flow-adjusted concentrations in the major rivers entering Chesapeake Bay were computed on the basis of water-quality data collected between 1985 and 1998 at 29 monitoring stations in the Susquehanna, Potomac, James, Rappahannock, York, Patuxent, and Choptank River Basins. Two computer models?the Chesapeake Bay Watershed Model (WSM) and the U.S. Geological Survey?s 'Spatially Referenced Regressions on Watershed attributes' (SPARROW) Model?were used to help explain the major factors affecting the trends. Results from WSM simulations provided information on temporal changes in contributions from major nutrient sources, and results from SPARROW model simulations provided spatial detail on the distribution of nutrient yields in these basins. Additional data on nutrient sources, basin characteristics, implementation of management practices, and ground-water inputs to surface water were analyzed to help explain the trends. The major factors affecting the trends were changes in nutrient sources and natural variations in streamflow. The dominant source of nitrogen and phosphorus from 1985 to 1998 in six of the seven tributary basins to Chesapeake Bay was determined to be agriculture. Because of the predominance of agricultural inputs, changes in agricultural nutrient sources such as manure and fertilizer, combined with decreases in agricultural acreage and implementation of best management practices (BMPs), had the greatest impact on the trends in flow-adjusted nutrient concentrations. Urban acreage and population, however, were noted to be increasing throughout the Chesapeake Bay Watershed, and as a result, delivered loads of nutrients from urban areas increased during the study period. Overall, agricultural nutrient management, in combination with load decreases from point sources due to facility upgrades and the phosphate detergent ban, led to downward trends in flow-adjusted nutrient concentrations atmany of the monitoring stations in the

  6. Sector Growth Demonstration in the Chesapeake Bay Watershed

    EPA Pesticide Factsheets

    EPA continues to work with the Bay states and DC to adress areas of concern identified in the final reports. EPA has asked each state and DC to prepare a Sector Load Growth Demonstration using the Sector Load Growth techical memorandum as a guide.

  7. Eliciting stakeholder values for coral reef management tasks in the Guánica Bay watershed, Puerto Rico

    EPA Science Inventory

    The EPA is developing a valuation protocol for southwest Puerto Rico that will support the US Coral Reef Task Force’s (USCRTF) Partnership Initiative in the Guánica Bay/Rio Loco (GB/RL) Watershed. The GB/RL watershed is located in southwestern Puerto Rico and includes the urbaniz...

  8. 77 FR 11111 - Assessment of Potential Large-Scale Mining on the Bristol Bay Watershed of Alaska: Nomination of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-24

    ... AGENCY Assessment of Potential Large-Scale Mining on the Bristol Bay Watershed of Alaska: Nomination of... impacts associated with potential large-scale mining development in the Nushagak and Kvichak watersheds of... how large-scale mining activities might affect water quality and habitat. EPA will focus primarily...

  9. 77 FR 14011 - Assessment of Potential Large-Scale Mining on the Bristol Bay Watershed of Alaska: Nomination of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-08

    ... AGENCY Assessment of Potential Large-Scale Mining on the Bristol Bay Watershed of Alaska: Nomination of... associated with potential large-scale mining development in the Nushagak and Kvichak watersheds of Bristol... understand how large-scale mining activities might affect water quality and habitat. EPA will focus...

  10. The USDA-ARS Walnut Gulch Experimental Watershed, Arizona, USA

    NASA Astrophysics Data System (ADS)

    Nichols, Mary; Nearing, Mark; Goodrich, Dave; Heilman, Phil

    2015-04-01

    The United States Department of Agriculture (USDA) has been supporting research and data collection at instrumented watershed throughout the country since the dust bowl era of the 1930's. In 1953, the USDA established the Walnut Gulch Experimental Watershed (WGEW) in southeastern Arizona near Tombstone to conduct hydrologic and erosion research to quantify the unique rainfall-runoff characteristics of semiarid regions and to understand the downstream effects of conservation practices implemented in watershed uplands. Instrumentation and research on the WGEW has expanded to include meteorological and flux measurements, soil moisture, and ecosystem responses. In addition, the WGEW serves as a validation site for aircraft and satellite based remotely sensed instruments. Core measurements have been used to quantify semiarid rainfall, runoff, infiltration, and transmission losses; develop and validate simulation models, and support broader, regional, basin scale research. The long-term database is a critical resource for advancing the scientific understanding of semiarid ecohydrological processes. The WGEW, its history, significant contributions to instrumentation development, and the current WGEW data collection program in the context of contemporary research questions will be presented.

  11. Modeling selenium bioaccumulation through arthropod food webs in San Francisco Bay, California, USA

    USGS Publications Warehouse

    Schlekat, C.E.; Purkerson, D.G.; Luoma, S.N.

    2004-01-01

    Trophic transfer is the main process by which upper trophic level wildlife are exposed to selenium. Transfers through lower levels of a predator's food web thus can be instrumental in determining the threat of selenium in an ecosystem. Little is known about Se transfer through pelagic, zooplankton-based food webs in San Francisco Bay ([SFB], CA, USA), which serve as an energy source for important predators such as striped bass. A dynamic multipathway bioaccumulation model was used to model Se transfer from phytoplankton to pelagic copepods to carnivorous mysids (Neomysis mercedis). Uptake rates of dissolved Se, depuration rates, and assimilation efficiencies (AE) for the model were determined for copepods and mysids in the laboratory. Small (73-250 ??m) and large (250-500 ??m) herbivorous zooplankton collected from SFB (Oithona/Limnoithona and Acartia sp.) assimilated Se with similar efficiencies (41-52%) from phytoplankton. Mysids assimilated 73% of Se from small herbivorous zooplankton; Se AE was significantly lower (61%) than larger herbivorous zooplankton. Selenium depuration rates were high for both zooplankton and mysids (12-25% d-1), especially compared to bivalves (2-3% d-1). The model predicted steady state Se concentrations in mysids similar to those observed in the field. The predicted concentration range (1.5-5.4 ??g g -1) was lower than concentrations of 4.5 to 24 ??g g-1 observed in bivalves from the bay. Differences in efflux between mysids and bivalves were the best explanation for the differences in uptake. The results suggest that the risk of selenium toxicity to predators feeding on N. mercedis would be less than the risk to predators feeding on bivalves. Management of selenium contamination should include food webs analyses to focus on the most important exposure pathways identified for a given watershed.

  12. Management of Urban Stormwater Runoff in the Chesapeake Bay Watershed

    USGS Publications Warehouse

    Hogan, Dianna M.

    2008-01-01

    Urban and suburban development is associated with elevated nutrients, sediment, and other pollutants in stormwater runoff, impacting the physical and environmental health of area streams and downstream water bodies such as the Chesapeake Bay. Stormwater management facilities, also known as Best Management Practices (BMPs), are increasingly being used in urban areas to replace functions, such as flood protection and water quality improvement, originally performed by wetlands and riparian areas. Scientists from the U.S. Geological Survey (USGS) have partnered with local, academic, and other Federal agency scientists to better understand the effectiveness of different stormwater management systems with respect to Chesapeake Bay health. Management of stormwater runoff is necessary in urban areas to address flooding and water quality concerns. Improving our understanding of what stormwater management actions may be best suited for different types of developed areas could help protect the environmental health of downstream water bodies that ultimately receive runoff from urban landscapes.

  13. Data Management Solutions for Tracking Restoration Progress in the Chesapeake Bay Watershed

    NASA Astrophysics Data System (ADS)

    Ravi, S. R.; Johnston, M.; Sweeney, J.

    2014-12-01

    The decline of the Chesapeake Bay estuarine ecosystem due to agricultural and industrial activities has been a great concern, where excess of dissolved nutrients combined with global climate change has lead to increased storm surges, habitat destruction, and low dissolved oxygen, reduced water clarity, and increased algal growth. In 2010 The US Environmental Protection Agency established the Chesapeake Bay Total Maximum Daily Load (TMDL), which seeks to protect the Bay's living resources by reducing nutrient and sediment runoff to its waters, and sets pollution reduction targets for sediment, nitrogen and phosphorus across 64000 sq. miles watershed that includes parts of six states - Delaware, Maryland, New York, Pennsylvania, Virginia, and West Virginia — and the entire District of Columbia. The Chesapeake Bay Program and the US EPA have developed a number of tools to track the progress of restoration. In this study we describe data management solutions, which were used in the integration of data such as land use, nutrient applications, management practices, policies among the bay jurisdictions, and a summary of a suite of tools that were developed and are being used to collect, process, and report data at various spatial scales for tracking the progress made by the seven Bay jurisdictions in achieving reductions in nutrient and sediment runoff. The described integration strategy and data management solutions can be used in the development and application of similar regulatory local or regional scale environmental management tools.

  14. Terrigenous Sedimentation Patterns at Reefs Adjacent to the Guanica Bay Watershed, Southwest Puerto Rico

    NASA Astrophysics Data System (ADS)

    Sherman, C.; Whitall, D.

    2014-12-01

    Guanica Bay is an estuary on the southwest coast of Puerto Rico with numerous nearshore reefs located in adjacent coastal waters. As part of the multi-agency Guanica Bay Watershed Project, a study was undertaken to establish baseline levels of terrigenous sedimentation reaching reefs adjacent to the Guanica Bay watershed as well as establish spatial and temporal patterns in its delivery. To characterize and quantify sedimentation patterns, sediment traps were established at nine reef sites occurring along an ~ 14 km stretch of coastline centered on the outlet of the bay. Sites were located at shallow reefs within 2 km of the shore at depths of ~ 10 m. Two additional sites were located at the mouth of the Rio Loco where it empties into Guanica Bay and at the mouth of the bay where it opens into adjacent coastal waters. Traps were collected monthly from August 2009 through July 2012 to determine both the amount of sediment accumulation (mg cm-2 day-1) and its composition. Composition is expressed in terms of relative amounts of calcium carbonate (in situ production), organic material and terrigenous material. Average trap accumulation rates among the reef sites ranged from ~ 3 to 28 mg cm-2 day-1. Average percent terrigenous material within reef accumulation ranged from ~ 20% to 30%. While trap accumulation rates are highly variable on both spatial and temporal scales, the composition of sediments and relative amount of terrigenous material is fairly uniform. Similar temporal patterns in accumulation rates among the sites without corresponding changes in composition of sediments point to resuspension of bottom sediments by wave action as a primary driver of sedimentary dynamics at these reefs. Sites closest to Guanica Bay display the highest degree of terrigenous influence in terms of trap accumulation rates and percent terrigenous material, which is consistent with Guanica Bay serving as a local source of terrigenous material to coastal waters. However, the lack of

  15. Links Between Watershed Activities and the Degradation of Coastal, Tidal Salt Marshes in Southern New England USA

    EPA Science Inventory

    Human activities (e.g., land development, wastewater) in coastal watersheds in New England USA are linked with community- and system-level changes in tidal, organic-rich salt marshes. Significant relationships between various indicators of watershed activities and ecosystem stru...

  16. Hydrologic data from urban watersheds in the Tampa Bay area, Florida

    USGS Publications Warehouse

    Lopez, Miguel A.; Michaelis, D.M.

    1979-01-01

    Hydrologic data are being collected in 10 urbanized watersheds located in the Tampa Bay area, Florida. The gaged watersheds have impervious areas that range from 19 percent for a residential watershed in north Tampa to nearly 100 percent for a downtown Tampa watershed. Land-use types, including roads, residential, commercial, industrial, institutional, recreational , and open space, have been determined for each watershed. Rainfall and storm runoff data collected since 1971 for one site and since 1975 for six other sites through September 1976, have been processed. These data are recorded at 5-minute intervals and are stored in the U. S. Geological Survey WATSTORE unit values file. Daily rainfall at 12 sites and daily pan evaporation at one site have been stored in the WATSTORE daily values file. Chemical and biological analyses of storm runoff for six sites, base flow for seven sites, and analyses of bottom material for seven sites are also stored in the WATSTORE water-quality files. Rainfall and storm runoff for selected storms, daily rainfall, and daily pan-evaporation data are summarized in this report. Water-quality analyses of all water-quality samples also are listed. (Woodard-USGS).

  17. Watershed Implications of Sediment and Nutrient Pollution in the Guánica Bay Watershed

    EPA Science Inventory

    The U.S. Coral Reef Task Force (USCRTF), a collaboration of federal, commonwealth, and non-government agencies, recently initiated a program to limit sediment runoff to the coral reefs outside Guánica Bay, Puerto Rico. Municipal and agricultural growth in the Guánic...

  18. Cytochrome P450 and organochlorine contaminants in black-crowned night-herons from the Chesapeake Bay region, USA

    USGS Publications Warehouse

    Rattner, B.A.; Melancon, M.J.; Rice, C.P.; Riley, W.; Eisemann, J.; Hines, R.K.

    1997-01-01

    Black-crowned night-heron (Nycticorax nycticorax) offspring were collected from a relatively uncontaminated coastal reference site (next to Chincoteague National Wildlife Refuge, VA, USA) and two sites in the Chesapeake Bay watershed (Baltimore Harbor, MD and Rock Creek Park, Washington, DC, USA). Hepatic microsomal activities of benzyloxyresorufin-O-dealkylase and ethoxyresorufin-O-dealkylase were significantly elevated (up to sixfold and ninefold induction, respectively) in pipping embryos from the Baltimore Harbor colony compared to the reference site, whereas values in embryos from the Rock Creek Park colony were intermediate. Concentrations of organochlorine pesticides and metabolites in pipping embryos from both sites in the Chesapeake watershed were greater than at the reference site but below the known threshold for reproductive impairment. However, concentrations of 10 arylhydrocarbon receptor-active polychlorinated biphenyl (PCB) congeners and estimated toxic equivalents were up to 37-fold greater in embryos collected from these two sites in the Chesapeake Bay region, with values for toxic congeners 77 and 126 exceeding those observed in pipping heron embryos from the Great Lakes. Monooxygenase activity of pipping embryos was associated with concentrations of several organochlorine pesticides, total PCBs, arylhydrocarbon receptor-active PCB congeners, and toxic equivalents (r = 0.30-0.59), providing further evidence of the value of cytochrome P450 as a biomarker of organic contaminant exposure. Organochlorine contaminant levels were greater in 10-d-old nestlings from Baltimore Harbor than the reference site but had no apparent effect on monooxygenase activity or growth. These findings demonstrate induction of cytochrome P450 in pipping black-crowned night-heron embryos in the Chesapeake Bay region, probably by exposure to PCB congeners of local origin, and the accumulation of organochlorine pesticides and metabolites in nestling herons from Baltimore

  19. Cytochrome P450 and organochlorine contaminants in black-crowned night-herons from the Chesapeake Bay region, USA

    USGS Publications Warehouse

    Rattner, Barnett A.; Melancon, Mark J.; Rice, Clifford P.; Riley, Walter; Eisemann, John D.; Hines, Randy K.

    1997-01-01

    Black-crowned night-heron (Nycticorax nycticorax) offspring were collected from a relatively uncontaminated coastal reference site (next to Chincoteague National Wildlife Refuge, VA, USA) and two sites in the Chesapeake Bay watershed (Baltimore Harbor, MD and Rock Creek Park, Washington, DC, USA). Hepatic microsomal activities of benzyloxyresorufin-O-dealkylase and ethoxyresorufin-O-dealkylase were significantly elevated (up to sixfold and ninefold induction, respectively) in pipping embryos from the Baltimore Harbor colony compared to the reference site, whereas values in embryos from the Rock Creek Park colony were intermediate. Concentrations of organochlorine pesticides and metabolites in pipping embryos from both sites in the Chesapeake watershed were greater than at the reference site but below the known threshold for reproductive impairment. However, concentrations of 10 arylhydrocarbon receptor-active polychlorinated biphenyl (PCB) congeners and estimated toxic equivalents were up to 37-fold greater in embryos collected from these two sites in the Chesapeake Bay region, with values for toxic congeners 77 and 126 exceeding those observed in pipping heron embryos from the Great Lakes. Monooxygenase activity of pipping embryos was associated with concentrations of several organochlorine pesticides, total PCBs, arylhydrocarbon receptor-active PCB congeners, and toxic equivalents (r = 0.30–0.59), providing further evidence of the value of cytochrome P450 as a biomarker of organic contaminant exposure. Organochlorine contaminant levels were greater in 10-d-old nestlings from Baltimore Harbor than the reference site but had no apparent effect on monooxygenase activity or growth. These findings demonstrate induction of cytochrome P450 in pipping black-crowned night-heron embryos in the Chesapeake Bay region, probably by exposure to PCB congeners of local origin, and the accumulation of organochlorine pesticides and metabolites in nestling herons from Baltimore

  20. Holocene climates and connections between the San Francisco Bay Estuary and its watershed: A review

    USGS Publications Warehouse

    Malamud-Roam, F.; Dettinger, M.; Ingram, B. Lynn; Hughes, Malcolm K.; Florsheim, Joan

    2007-01-01

    This review of paleoclimate records reveals a gradual warming and drying in California from about 10,000 years to about 4,000 years before present. During this period, the current Bay and Delta were inundated by rising sea level so that by 4,000 years ago the Bay and Delta had taken on much of their present shape and extent. Between about 4,000 and 2,000 years ago, cooler and wetter conditions prevailed in the watershed, lowering salinity in the Estuary and altering local ecosystems. Those wetter conditions gave way to increasing aridity during the past 2,000 years, a general trend punctuated by occasional prolonged and severe droughts and occasional unusually wet, cool periods. California’s climate since A.D. 1850 has been unusually stable and benign, compared to climate variations during the previous 2,000 or more years. Thus, climate variations in California’s future may be even more (perhaps much more) challenging than those of the past 100 years. To improve our understanding of these past examples of climate variability in California, and of the linkages between watershed climate and estuarine responses, greater emphases on paleoclimate records in and around the Estuary, improved temporal resolutions in several record types, and linked watershed-estuary paleo-modeling capabilities are needed. 

  1. Subsurface transport of orthophosphate in five agricultural watersheds, USA

    USGS Publications Warehouse

    Domagalski, Joseph L.; Johnson, Henry M.

    2011-01-01

    Concentrations of dissolved orthophosphate (ortho P) in the unsaturated zone, groundwater, tile drains, and groundwater/stream water interfaces were assessed in five agricultural watersheds to determine the potential for subsurface transport. Concentrations of iron oxides were measured in the aquifer material and adsorption of ortho P on oxide surfaces was assessed by geochemical modeling. Attenuation of ortho P in these aquifers was attributed primarily to sorption onto iron oxides, and in one location onto clay minerals. Only one location showed a clear indication of phosphorus transport to a stream from groundwater discharge, although groundwater did contribute to the stream load elsewhere. Subsurface ortho P movement at a site in California resulted in a plume down gradient from orchards, which was attenuated by a 200 m thick riparian zone with natural vegetation. Iron oxides had an effect on phosphorus movement and concentrations at all locations, and groundwater chemistry, especially pH, exerted a major control on the amount of phosphorus adsorbed. Groundwater pH at a site in Maryland was below 5 and that resulted in complete sequestration of phosphorus and no movement toward the stream. Geochemical modeling indicated that as the surfaces approached saturation, groundwater concentrations of ortho P rise rapidly.

  2. Quantifying the impact of watershed urbanization on a coral reef: Maunalua Bay, Hawaii

    NASA Astrophysics Data System (ADS)

    Wolanski, Eric; Martinez, Jonathan A.; Richmond, Robert H.

    2009-09-01

    Human activities in the watersheds surrounding Maunalua Bay, Oahu, Hawaii, have lead to the degradation of coastal coral reefs affecting populations of marine organisms of ecological, economic and cultural value. Urbanization, stream channelization, breaching of a peninsula, seawalls, and dredging on the east side of the bay have resulted in increased volumes and residence time of polluted runoff waters, eutrophication, trapping of terrigenous sediments, and the formation of a permanent nepheloid layer. The ecosystem collapse on the east side of the bay and the prevailing westward longshore current have resulted in the collapse of the coral and coralline algae population on the west side of the bay. In turn this has lead to a decrease in carbonate sediment production through bio-erosion as well as a disintegration of the dead coral and coralline algae, leading to sediment starvation and increased wave breaking on the coast and thus increased coastal erosion. The field data and resulting coral reef ecohydrology model presented in this paper demonstrate and quantify the importance of biophysical processes leading to coral reef degradation as the result of urbanization. Coral restoration in Maunalua Bay will require an integrated ecosystem approach.

  3. Residence times and nitrate transport in ground water discharging to streams in the Chesapeake Bay Watershed

    USGS Publications Warehouse

    Lindsey, Bruce D.; Phillips, Scott; Donnelly, Colleen A.; Speiran, Gary K.; Plummer, L. Niel; Bohlke, John-Karl; Focazio, Michael J.; Burton, William C.; Busenberg, Eurybiades

    2003-01-01

    One of the major water-quality problems in the Chesapeake Bay is an overabundance of nutrients from the streams and rivers that discharge to the Bay. Some of these nutrients are from nonpoint sources such as atmospheric deposition, agricultural manure and fertilizer, and septic systems. The effects of efforts to control nonpoint sources, however, can be difficult to quantify because of the lag time between changes at the land surface and the response in the base-flow (ground water) component of streams. To help resource managers understand the lag time between implementation of management practices and subsequent response in the nutrient concentrations in the base-flow component of streamflow, a study of ground-water discharge, residence time, and nitrate transport in springs throughout the Chesapeake Bay Watershed and in four smaller watersheds in selected hydrogeomorphic regions (HGMRs) was conducted. The four watersheds were in the Coastal Plain Uplands, Piedmont crystalline, Valley and Ridge carbonate, and Valley and Ridge siliciclastic HGMRs. A study of springs to estimate an apparent age of the ground water was based on analyses for concentrations of chlorofluorocarbons in water samples collected from 48 springs in the Chesapeake Bay Watershed. Results of the analysis indicate that median age for all the samples was 10 years, with the 25th percentile having an age of 7 years and the 75th percentile having an age of 13 years. Although the number of samples collected in each HGMR was limited, there did not appear to be distinct differences in the ages between the HGMRs. The ranges were similar between the major HGMRs above the Fall Line (modern to about 50 years), with only two HGMRs of small geographic extent (Piedmont carbonate and Mesozoic Lowland) having ranges of modern to about 10 years. The median values of all the HGMRs ranged from 7 to 11 years. Not enough samples were collected in the Coastal Plain for comparison. Spring samples showed slightly

  4. Late Holocene Environmental History of the Los Osos Watershed, Morro Bay, CA

    NASA Astrophysics Data System (ADS)

    Broadman, E.; Reidy, L. M.; Wahl, D.

    2014-12-01

    A comprehensive understanding of past changes in wetland ecosystems is integral for creating policies for modern land use practices. The Morro Bay salt marsh is home to a large wetland that has experienced significant environmental impacts in the last few centuries. In this study, sediment cores from the Morro Bay salt marsh were analyzed to discern changes in environment since the time of European contact, which occurred in 1772. The marsh is fed by two creeks (Chorro and Los Osos) and their associated watersheds. Sediment cores taken from a portion of the marsh fed by Los Osos creek were analyzed and the results compared to those from previous studies on cores taken from the Chorro and Los Osos portions of the marsh. Magnetic susceptibility, loss on ignition, pollen, radiocarbon, and X-ray fluorescence (XRF) analyses were conducted. An age-depth model was established for the Los Osos cores using two radiocarbon dates, as well as Erodium cicutarium as a chronological marker. Preliminary pollen analysis from Chorro marsh cores indicates vegetation shifts at the time of contact, when the salt marsh formed. Magnetic susceptibility and XRF data indicate dramatically increased rates of erosion from the time of contact consistently until the present. Influx of non-carbonate inorganic material also indicates a rapid increase in sedimentation in the marsh starting at the time of contact. Comparison of sedimentation rates between the two creeks suggests that differences in watershed geomorphology and land use practices have had pronounced impacts on erosional processes. Over the last decade, the Morro Bay National Estuary Program (MBNEP) has taken more measures to reduce erosion and sedimentation rates in the Chorro watershed, as is reflected by reduced sedimentation rates in MBNEP data collected within the last few years. Our study helps to elucidate the impacts of anthropogenic land use change on wetland systems, and provides much needed data to policy makers seeking to

  5. Water storage at the Panola Mountain Research Watershed, Georgia, USA

    USGS Publications Warehouse

    Peters, N.E.; Aulenbach, Brent T.

    2011-01-01

    Storage is a major component of a catchment water balance particularly when the water balance components are evaluated on short time scales, that is, less than annual. We propose a method of determining the storage-discharge relation using an exponential function and daily precipitation, potential evapotranspiration (PET) and baseflow during the dormant season when evapotranspiration (ET) is low. The method was applied to the 22-year data series of the 0.41-ha forested Panola Mountain Research Watershed, Georgia. The relation of cumulative daily precipitation minus daily runoff and PET versus baseflow was highly significant (r2=0.92, p<0.0001), but the initial storage for each year varied markedly. For the 22-year study period, annual precipitation and runoff averaged 1240 and 380mm, respectively, whereas the absolute catchment storage range was ~400mm, averaging 219mm annually, which is attributed to contributions of soil water and groundwater. The soil moisture of a catchment average 1-m soil depth was evaluated and suggests that there was an active (changes in soil storage during stormflow) and passive (a longer-term seasonal cycle) soil water storage with ranges of 40-70 and 100-120mm, respectively. The active soil water storage was short term on the order of days during and immediately after rainstorms, and the passive or seasonal soil storage was highest during winter when ET was lowest and lowest during summer when ET was highest. An estimate of ET from daily changes in soil moisture (ETSM) during recessions was comparable with PET during the dormant season (1.5mmday-1) but was much lower during the growing season (June through August); monthly average SMET and PET ranged from 2.8 to 4.0mmday-1 and from 4.5 to 5.5mmday-1, respectively. The growing season difference is attributed to the overestimation of PET. ETSM estimates were comparable with those derived from hillslope water balances during sprinkling experiments. Master recession curves derived from the

  6. A cross-site comparison of factors influencing soil nitrification rates in northeastern USA forested watersheds

    USGS Publications Warehouse

    Ross, D.S.; Wemple, B.C.; Jamison, A.E.; Fredriksen, G.; Shanley, J.B.; Lawrence, G.B.; Bailey, S.W.; Campbell, J.L.

    2009-01-01

    Elevated N deposition is continuing on many forested landscapes around the world and our understanding of ecosystem response is incomplete. Soil processes, especially nitrification, are critical. Many studies of soil N transformations have focused on identifying relationships within a single watershed but these results are often not transferable. We studied 10 small forested research watersheds in the northeastern USA to determine if there were common factors related to soil ammonification and nitrification. Vegetation varied between mixed northern hardwoods and mixed conifers. Watershed surface soils (Oa or A horizons) were sampled at grid or transect points and analyzed for a suite of chemical characteristics. At each sampling point, vegetation and topographic metrics (field and GIS-based) were also obtained. Results were examined by watershed averages (n = 10), seasonal/watershed averages (n = 28), and individual sampling points (n = 608). Using both linear and tree regression techniques, the proportion of conifer species was the single best predictor of nitrification rates, with lower rates at higher conifer dominance. Similar to other studies, the soil C/N ratio was also a good predictor and was well correlated with conifer dominance. Unlike other studies, the presence of Acer saccharum was not by itself a strong predictor, but was when combined with the presence of Betula alleghaniensis. Topographic metrics (slope, aspect, relative elevation, and the topographic index) were not related to N transformation rates across the watersheds. Although found to be significant in other studies, neither soil pH, Ca nor Al was related to nitrification. Results showed a strong relationship between dominant vegetation, soil C, and soil C/N. ?? 2008 Springer Science+Business Media, LLC.

  7. Silver concentrations in Colorado, USA, watersheds using improved methodology.

    PubMed

    Wen, Liang-Saw; Santschi, Peter H; Gill, Gary A; Tang, Degui

    2002-10-01

    River water samples were collected at five sites in the state of Colorado, USA, to assess the impact of municipal and industrial discharges on Ag concentrations and speciation in surface waters. Samples were collected and analyzed for total (unfiltered collections), filtered (0.1 and 0.4 microm), particulate (> or = 0.45 microm), and colloidal Ag (3 kDa-0.1 m) using ultraclean protocols. A series of laboratory experiments were conducted to assess bias from sample storage, digestion, and preconcentration protocols. In general, upstream unfiltered and particulate Ag concentrations fell within a fairly narrow range, 3.1 to 21 ng/L and 0.2 to 1.7 microg/g, respectively. Downstream unfiltered and particulate Ag concentrations showed a more broad range, 2.8 to 1,110 ng/L and 0.5 to 104 microg/g, respectively, and reflected attenuated impacts of Ag-laden discharge effluents. However, Ag concentrations in the 0.1-microm filter-passing fraction 0.8 to 1.2 km downstream from major treatment plant effluents were all below the chronic silver criteria. On average, more than 60% of the 0.1-microm filter-passing Ag was associated with colloidal macromolecular organic matter. Silver concentrations in colloids (microg/g) were, on average, the same as those in suspended particulate matter. The percentage abundance of colloidal Ag was similar to that of dissolved organic carbon, suggesting that strong Ag binding ligands exist in both the colloidal and the particle size fractions, as these macromolecular ligands likely play a major role in Ag speciation.

  8. Facilitating adaptive management in the Chesapeake Bay Watershed through the use of online decision support tools

    USGS Publications Warehouse

    Mullinx, Cassandra; Phillips, Scott; Shenk, Kelly; Hearn, Paul; Devereux, Olivia

    2009-01-01

    The Chesapeake Bay Program (CBP) is attempting to more strategically implement management actions to improve the health of the Nation’s largest estuary. In 2007 the U.S. Geological Survey (USGS) and U.S. Environmental Protection Agency (USEPA) CBP office began a joint effort to develop a suite of Internetaccessible decision-support tools and to help meet the needs of CBP partners to improve water quality and habitat conditions in the Chesapeake Bay and its watersheds. An adaptive management framework is being used to provide a structured decision process for information and individual tools needed to implement and assess practices to improve the condition of the Chesapeake Bay ecosystem. The Chesapeake Online Adaptive Support Toolkit (COAST) is a collection of web-based analytical tools and information, organized in an adaptive management framework, intended to aid decisionmakers in protecting and restoring the integrity of the Bay ecosystem. The initial version of COAST is focused on water quality issues. During early and mid- 2008, initial ideas for COAST were shared and discussed with various CBP partners and other potential user groups. At these meetings, test cases were selected to help improve understanding of the types of information and analytical functionality that would be most useful for specific partners’ needs. These discussions added considerable knowledge about the nature of decisionmaking for Federal, State, local and nongovernmental partners. Version 1.0 of COAST, released in early winter of 2008, will be further reviewed to determine improvements needed to address implementation and assessment of water quality practices. Future versions of COAST may address other aspects of ecosystem restoration, including restoration of habitat and living resources and maintaining watershed health.

  9. BENTHIC MACROFAUNA-HABITAT ASSOCIATIONS IN WILLAPA BAY, WASHINGTON, USA

    EPA Science Inventory

    Estuary-wide benthic macrofauna-habitat associations in Willapa Bay, Washington, United States, were determined for 4 habitats (eelgrass [Zostera marina], Atlantic cordgrass [Spartina alterniflora], mud shrimp [Upogebia pugettensis], ghost shrimp [Neotrypaea californiensis]) in 1...

  10. Understanding Urban Watersheds through Digital Interactive Maps, San Francisco Bay Area, California

    NASA Astrophysics Data System (ADS)

    Sowers, J. M.; Ticci, M. G.; Mulvey, P.

    2014-12-01

    Dense urbanization has resulted in the "disappearance" of many local creeks in urbanized areas surrounding the San Francisco Bay. Long reaches of creeks now flow in underground pipes. Municipalities and water agencies trying to reduce non-point-source pollution are faced with a public that cannot see and therefore does not understand the interconnected nature of the drainage system or its ultimate discharge to the bay. Since 1993, we have collaborated with the Oakland Museum, the San Francisco Estuary Institute, public agencies, and municipalities to create creek and watershed maps to address the need for public understanding of watershed concepts. Fifteen paper maps are now published (www.museumca.org/creeks), which have become a standard reference for educators and anyone working on local creek-related issues. We now present digital interactive creek and watershed maps in Google Earth. Four maps are completed covering urbanized areas of Santa Clara and Alameda Counties. The maps provide a 3D visualization of the watersheds, with cartography draped over the landscape in transparent colors. Each mapped area includes both Present and Past (circa 1800s) layers which can be clicked on or off by the user. The Present layers include the modern drainage network, watershed boundaries, and reservoirs. The Past layers include the 1800s-era creek systems, tidal marshes, lagoons, and other habitats. All data are developed in ArcGIS software and converted to Google Earth format. To ensure the maps are interesting and engaging, clickable icons pop-up provide information on places to visit, restoration projects, history, plants, and animals. Maps of Santa Clara Valley are available at http://www.valleywater.org/WOW.aspx. Maps of western Alameda County will soon be available at http://acfloodcontrol.org/. Digital interactive maps provide several advantages over paper maps. They are seamless within each map area, and the user can zoom in or out, and tilt, and fly over to explore

  11. Tumor prevalence and biomarkers of exposure in brown bullheads (Ameiurus nebulosus) from the tidal Potomac River, USA, watershed

    USGS Publications Warehouse

    Pinkney, A.E.; Harshbarger, J.C.; May, E.B.; Melancon, M.J.

    2001-01-01

    Associations between contaminant exposure and liver and skin tumor prevalence were evaluated in brown bullheads (Ameiurus nebulosus) from the tidal Potomac River, USA, watershed. Thirty bullheads (>age 3) were collected from Quantico embayment near a Superfund site that released organochlorine contaminants; Neabsco Creek, a tributary with petroleum inputs from runoff and marinas; and Anacostia River (spring and fall), an urban tributary designated as a Chesapeake Bay region of concern, that was contaminated with polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and organochlorine pesticides. Fish were collected from the Tuckahoe River, as a reference. Cytochrome P450 activity, bile PAH metabolites, and muscle organochlorine pesticide and PCB concentrations were measured in randomly selected individuals and sediment contaminants were analyzed. We found statistically significant differences in liver tumor prevalences: Anacostia (spring), 50%, Anacostia (fall), 60%, Neabsco, 17%, Quantico, 7%, and Tuckahoe, 10%. Skin tumor prevalences were significantly different: Anacostia (spring), 37%, Anacostia (fall), 10%, Neabsco, 3%, Quantico, 3%, and Tuckahoe, 0%. Tumor prevalences in Anacostia bullheads warrants concern and was similar to those as highly contaminated sites in the Great Lakes. Evidence was found of higher PAH exposure in Anacostia fish but a cause-effect linkage could not be established. Fish tumor surveys, with histopathologic examination of internal and external organs are recommended for monitoring the status of regions of concern.

  12. Tumor prevalence and biomarkers of exposure in brown bullheads (Ameiurus nebulosus) from the tidal Potomac River, USA, watershed.

    PubMed

    Pinkney, A E; Harshbarger, J C; May, E B; Melancon, M J

    2001-06-01

    Associations between contaminant exposure and liver and skin tumor prevalence were evaluated in brown bullheads (Ameiurus nebulosus) from the tidal Potomac River, USA, watershed. Thirty bullheads (> or = age 3) were collected from Quantico embayment, near a Superfund site that released organochlorine contaminants; Neabsco Creek, a tributary with petroleum inputs from runoff and marinas; and Anacostia River (spring and fall), an urban tributary designated as a Chesapeake Bay region of concern, that was contaminated with polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and organochlorine pesticides. Fish were collected from the Tuckahoe River, as a reference. Cytochrome P450 activity, bile PAH metabolites, and muscle organochlorine pesticide and PCB concentrations were measured in randomly selected individuals and sediment contaminants were analyzed. We found statistically significant differences in liver tumor prevalences: Anacostia (spring), 50%; Anacostia (fall), 60%; Neabsco, 17%; Quantico, 7%; and Tuckahoe, 10%. Skin tumor prevalences were significantly different: Anacostia (spring), 37%; Anacostia (fall), 10%; Neabsco, 3%; Quantico, 3%; and Tuckahoe, 0%. Tumor prevalence in Anacostia bullheads warrants concern and was similar to those at highly contaminated sites in the Great Lakes. Evidence was found of higher PAH exposure in Anacostia fish but a cause-effect linkage could not be established. Fish tumor surveys, with histopathologic examination of internal and external organs, are recommended for monitoring the status of regions of concern.

  13. ``Carolina Bays" on the Georgia (USA) Coastal Plain: Meteoritic Origin Revisited

    NASA Astrophysics Data System (ADS)

    Albin, E. F.

    2001-11-01

    In this investigation, forty-four elliptical depressions, with diameters > 1.0 km, have been mapped across the Georgia (USA) coastal plain. These curious features are often called pocosins (an Algonquin name for a bay-covered swamp); however, in the literature the depressions are the so-called ``Carolina Bays" [1]. Controversy has surrounded the origin of the Carolina Bays since they were first recognized in the late eighteenth century [e.g., 2]. Although terrestrial processes have been invoked to explain their origin, a meteoritic related mode of formation cannot be ruled out. Aerial imagery shows the bays on the Georgia coastal plain as dark ovals surrounded by white to light-gray rims. These rims are composed of sandy deposits that are typically less than two meters high and are better developed in the southeastern part of the oval. Magnetic anomalies occur outside of most bay depressions, approximately the distance of the short axis of the bay away from the southeastern rim. On a regional scale, bay trend is from NW to SE -- with the southern most occurring bays having a slight clockwise orientation relative to those found farther north. Arabia Bay, a 4.5 x 6.0 km feature, in Clinch County is the largest bay identified in Georgia. It is suggested that bays are late Pleistocene features produced by a series of ``Tunguska-like" atmospheric bursts associated with the fall of a massive chondritic or cometary bolide. Associated air-shock waves plowed into soft sediments, across the eastern North American coastal plain (from New Jersey to Georgia), forming a myriad of shallow depressions along its path. Further research, including laboratory modeling and field investigations, is ongoing. References: [1] Prouty, W.F., 1952, Bull. Geol. Soc. Amer., 63, 167-224. [2] Savage, H., 1982, The Mysterious Carolina Bays, Univ. South Carolina Press, 121 p.

  14. The exotic mute swan (Cygnus olor) in Chesapeake Bay, USA

    USGS Publications Warehouse

    Perry, M.C.; Perry, M.C.

    2002-01-01

    The exotic mute swan (Cygnus olor) has increased its population size in Chesapeake Bay (Maryland and Virginia) to approximately 4,500 since 1962 when five swans were released in the Bay. The Bay population of mute swans now represents 30% of the total Atlantic Flyway population (12,600) and has had a phenomenal increase of 1,200% from 1986 to 1999. Unlike the tundra swans (Cygnus columbianus) that migrate to the Bay for the winter, the mute swan is a year-long resident, and, therefore, reports of conflicts with nesting native waterbirds and the consumption of submerged aquatic vegetation (SAV) have raised concerns among resource managers. Populations of black skimmers (Rynchops niger) and least terns (Sterna antillarum) nesting on beaches and oyster shell bars have been eliminated by molting mute swans. Although data on the reduction of SAV by nesting mute swans and their offspring during the spring and summer are limited, food habits data show that mute swans rely heavily on SAV during these months. Widgeon grass (Ruppia maritima) constituted 56% and eel grass (Zostera marina) constituted 43% of the gullet food of mute swans. Other SAV and invertebrates (including bryozoans, shrimp, and amphipods) formed a much smaller amount of the food percentage (1%). Invertebrates are believed to have been selected accidently within the vegetation eaten by the swans. Corn (Zea mays) fed to swans by Bay residents during the winter probably supplement limited vegetative food resources in late winter. A program to control swan numbers by the addling of eggs and the killing of adult swans has been a contentious issue with some residents of the Bay area. A management plan is being prepared by a diverse group of citizens appointed by the Governor to advise the Maryland Department of Natural Resources on viable and optimum options to manage mute swans in the Maryland portion of Chesapeake Bay. Hopefully, the implementation of the plan will alleviate the existing conflicts to the

  15. Watershed storage-baseflow relations and monthly water balances at Panola Mountain Research Watershed, Georgia, U.S.A

    NASA Astrophysics Data System (ADS)

    Aulenbach, B. T.; Peters, N. E.; Freer, J. E.

    2012-12-01

    Watershed storage is a significant part of a catchment water budget, especially at smaller time scales, but is difficult to measure or estimate. A watershed storage-baseflow relation was developed by combining a stream baseflow-recession analysis with a watershed water budget during the dormant season where calculated potential evapotranspiration (PET) was similar to actual evapotranspiration (ET). The relation was developed during baseflow periods such that transient storage, as occurs during hydrologic events, was minimized. The analysis was applied to the Panola Mountain Research Watershed, a small 0.41-hectare forested watershed near Atlanta, Georgia, U.S.A., and resulted in a highly significant relation (R2=0.92, p<0.0001). The watershed storage-baseflow relation was then used to estimate changes in storage during baseflow conditions on a monthly basis. Baseflow storage ranged by 430 mm over the 22-year study period, water years 1986-2007, with an average interannual range of 247 mm. Baseflow and storage peaked at the beginning of April and was at its lowest at the beginning of September. Monthly storage increased an average of 27 mm/month during the dormant season (November - February) and declined by an average of 14 mm/month during the growing season (April - September). The greatest declines in storage were calculated for April and May, averaging 39 and 44 mm/month, respectively. Theses declines were the result of high baseflow runoff in addition to increased ET at the onset of the growing season. The incorporation of storage into annual water budgets modified calculated water yields, changing the range of annual yields from 16-50% to 9.7-46%. Since changes in baseflow storage are now estimated, ET can be calculated by difference using the water budget equation (ignoring transient storage changes). ET averaged about 40 mm/month during the dormant season and 88 mm/month during the growing season and peaked with an average of 123 mm/month in July. ET

  16. Modeling of Selenium for the San Diego Creek Watershed and Newport Bay, California

    USGS Publications Warehouse

    Presser, Theresa S.; Luoma, Samuel N.

    2009-01-01

    The San Diego Creek watershed and Newport Bay in southern California are contaminated with selenium (Se) as a result of groundwater associated with urban development overlying a historical wetland, the Swamp of the Frogs. The primary Se source is drainage from surrounding seleniferous marine sedimentary formations. An ecosystem-scale model was employed as a tool to assist development of a site-specific Se objective for the region. The model visualizes outcomes of different exposure scenarios in terms of bioaccumulation in predators using partitioning coefficients, trophic transfer factors, and site-specific data for food-web inhabitants and particulate phases. Predicted Se concentrations agreed well with field observations, validating the use of the model as realistic tool for testing exposure scenarios. Using the fish tissue and bird egg guidelines suggested by regulatory agencies, allowable water concentrations were determined for different conditions and locations in the watershed and the bay. The model thus facilitated development of a site-specific Se objective that was locally relevant and provided a basis for step-by-step implementation of source control.

  17. Assessments of urban growth in the Tampa Bay watershed using remote sensing data

    USGS Publications Warehouse

    Xian, G.; Crane, M.

    2005-01-01

    Urban development has expanded rapidly in the Tampa Bay area of west-central Florida over the past century. A major effect associated with this population trend is transformation of the landscape from natural cover types to increasingly impervious urban land. This research utilizes an innovative approach for mapping urban extent and its changes through determining impervious surfaces from Landsat satellite remote sensing data. By 2002, areas with subpixel impervious surface greater than 10% accounted for approximately 1800 km2, or 27 percent of the total watershed area. The impervious surface area increases approximately three-fold from 1991 to 2002. The resulting imperviousness data are used with a defined suite of geospatial data sets to simulate historical urban development and predict future urban and suburban extent, density, and growth patterns using SLEUTH model. Also examined is the increasingly important influence that urbanization and its associated imperviousness extent have on the individual drainage basins of the Tampa Bay watershed. ?? 2005 Elsevier Inc. All rights reserved.

  18. IMPACT OF STORM-WATER OUTFALLS ON SEDIMENT QUALITY IN CORPUS CHRISTI BAY, TEXAS, USA

    EPA Science Inventory

    To determine the quality of sediments and extent of contaminant impacts, a Sediment Quality Triad (SQT) study was conducted at 36 sites in the Corpus Christi Bay, Texas, USA, system. Fifteen of the 36 sites were located near storm-water outfalls, but 13 other sites (i.e., industr...

  19. BACTERIOPLANKTON DYNAMICS IN PENSACOLA BAY, FL, USA: ROLE OF PHYTOPLANKTON AND DETRIAL CARBON SOURCES

    EPA Science Inventory

    Bacterioplankton Dynamics in Pensacola Bay, FL, USA: Role of Phytoplankton and Detrital Carbon Sources (Abstract). To be presented at the16th Biennial Conference of the Estuarine Research Foundation, ERF 2001: An Estuarine Odyssey, 4-8 November 2001, St. Pete Beach, FL. 1 p. (ER...

  20. The relative importance of road density and physical watershed features in determining coastal marsh water quality in Georgian Bay.

    PubMed

    Decatanzaro, Rachel; Cvetkovic, Maja; Chow-Fraser, Patricia

    2009-09-01

    We used a GIS-based approach to examine the influence of road density and physical watershed features (watershed size, wetland cover, and bedrock type) on water quality in coastal marshes of Georgian Bay, Ontario. We created a GIS that included landscape information and water-quality data from a 9-year synoptic survey of 105 coastal marshes covering 28 quaternary watersheds. Multiple regressions and partial correlations were used to discern confounding effects of human-induced (road density) versus natural physical watershed determinants of water quality. Road density was the dominant factor influencing many water quality variables, showing positive correlations with specific conductivity (COND), total suspended solids (TSS), and inorganic suspended solids (ISS) and a negative correlation with overall Water Quality Index scores. Road density also showed positive correlations with total nitrate nitrogen (TNN) and total phosphorus (TP). By comparison, larger watershed area was the main factor leading to elevated TP concentrations. The proportion of the watershed occupied by wetlands explained the largest amount of variation in TNN concentrations (negative correlation) and was also negatively correlated with COND and positively correlated with TSS and ISS when we controlled for road density. Bedrock type did not have a significant effect in any of the models. Our findings suggest that road density is currently the overriding factor governing water quality of coastal marshes in Georgian Bay during the summer low-flow period. We recommend that natural variation in physical watershed characteristics be considered when developing water quality standards and management practices for freshwater coastal areas.

  1. Surface Soil Carbon, Nitrogen and Tree Species are Tightly Linked in Northeastern USA Forested Watersheds

    NASA Astrophysics Data System (ADS)

    Ross, D. S.; Juillerat, J.

    2008-12-01

    We measured C and N ratios in 608 surface soil horizons (primarily Oa) from ten small watersheds at seven established research sites in the northeastern USA. The dominant tree species included sugar maple (Acer saccharum), yellow birch (Betula alleghaniensis), American beech (Fagus grandifolia), red spruce (Picea rubens) and eastern hemlock (Tsuga canadensis). In the soil, both the C (50-530 g/kg) and C/N ratio (11.6- 45.3) had a wide distribution. In all but the Cone Pond watershed, both N concentration and the C/N ratio were positively and linearly related to C content. For these nine watersheds, the average N (g/kg) = 6.9 + 0.030 X C (g/kg), R2 = 0.97. The C/N ratios at Cone were much higher than would be predicted from the other data and charcoal was found in numerous samples, suggesting a source of recalcitrant C. Across all watersheds, C concentration was also positively correlated with forest floor depth (and therefore C pools). Although sugar maple dominance was negatively correlated with C/N ratio and C, better relationships were obtained by combining species. Carbon concentration of the humified surface horizon was negatively related to maple + birch dominance and positively related to conifer + beech dominance. Among nine of these ten watersheds, the average C concentration in the surface soil varied (187-441 g/kg) with a constant C/N ratio of 33. The remarkably tight relationships between C, N, and species suggest predicable patterns in C accumulation.

  2. Mobile data buoy system. [water quality measurements in watersheds and Mobile Bay, Alabama

    NASA Technical Reports Server (NTRS)

    Morton, R. A.

    1975-01-01

    The Mobile Data Buoy System was conceived to serve the users requirement for obtaining water quality parameters from two separate watershed systems. In view of the cost constraints of the ERTS program it was obvious that the network of 10 sampling stations required could not be of the fixed installation type; therefore, it was decided to go to a system of battery powered buoys of a size that could be used in one watershed system for a period of time and then moved to another by use of a relatively small 6.7 m (22 foot) boat. The basic idea of the water quality measurement program was to establish the water quality pattern of change from the headwaters of the watersheds to and through the Mobile Bay. This would allow the investigator to develop a good picture of the state's major water resources and the pressures from pollution that are being imposed. At this point in deployment of this mobile system of buoys, it is too early to put a quantitative value on the system, however it appears less expensive than known fixed installations as to first cost. It has a basic advantage in that it can be moved, at very little expense, to alternate sites where it is desired to obtain water quality data. It is to be noted this buoy system which covers a 80 Km (50 mile) stretch of the Black Warrior River and then skips down 483 Km (300 miles) to Mobile Bay for the next measurements would not be feasible unless there is a satellite to collect and relay the data.

  3. Digital data used to relate nutrient inputs to water quality in the Chesapeake Bay watershed, version 3.0

    USGS Publications Warehouse

    Brakebill, John W.; Preston, Stephen D.

    2004-01-01

    Chesapeake Bay restoration efforts are focused on improving water quality, living resources, and ecological habitats by 2010. One aspect of the water-quality restoration is the refinement of strategies designed to implement nutrient-reduction practices within the Bay watershed. These strategies are being refined and implemented by resource managers of the Chesapeake Bay Program (CBP), a partnership comprised of various Federal, State, and local agencies that includes jurisdictions within Delaware, Maryland, New York, Pennsylvania, Virginia, West Virginia, and the District of Columbia. The U.S. Geological Survey (USGS), an active member of the CBP, provides necessary water-quality information for these Chesapeake Bay nutrient-reduction strategy revisions and evaluations. The formulation and revision of effective nutrient-reduction strategies requires detailed scientific information and an analytical understanding of the sources, transport, and delivery of nutrients to the Chesapeake Bay. The USGS is supporting these strategies by providing scientific information to resource managers that can help them evaluate and understand these processes. One statistical model available to resource managers is a collection of SPAtially Referenced Regressions On Watershed (SPARROW) attributes, which uses a nonlinear regression approach to spatially relate nutrient sources and watershed characteristics to nutrient loads of streams throughout the Chesapeake Bay watershed. Developed by the USGS, information generated by SPARROW can help resource managers determine the geographical distribution and relative contribution of nutrient sources and the factors that affect their transport to the Bay. Nutrient source information representing the late 1990s time period was obtained from several agencies and used to create and compile digital spatial datasets of total nitrogen and total phosphorus contributions that served as input sources to the SPARROW models. These data represent

  4. Using Remote Sensing Data to Evaluate Habitat Loss in the Mobile, Galveston, and Tampa Bay Watersheds

    NASA Technical Reports Server (NTRS)

    Steffen, Morgan; Estes, Maurice G.; Al-Hamdan, Mohammad

    2010-01-01

    The Gulf of Mexico has experienced dramatic wetland habitat area losses over the last two centuries. These losses not only damage species diversity, but contribute to water quality, flood control, and aspects of the Gulf coast economy. Overall wetland losses since the 1950s were examined using land cover/land use (LCLU) change analysis in three Gulf coast watershed regions: Mobile Bay, Galveston Bay, and Tampa Bay. Two primary causes of this loss, LCLU change and climate change, were then assessed using LCLU maps, U.S. census population data, and available current and historical climate data from NOAA. Sea level rise, precipitation, and temperature effects were addressed, with emphasis on analysis of the effects of sea level rise on salt marsh degradation. Ecological impacts of wetland loss, including fishery depletion, eutrophication, and hypoxia were addressed using existing literature and data available from NOAA. These ecological consequences in turn have had an affect on the Gulf coast economy, which was analyzed using fishery data and addressing public health impacts of changes in the environment caused by wetland habitat loss. While recent federal and state efforts to reduce wetland habitat loss have been relatively successful, this study implies a need for more aggressive action in the Gulf coast area, as the effects of wetland loss reach far beyond individual wetland systems themselves to the Gulf of Mexico as a whole.

  5. Web-based decision support and visualization tools for water quality management in the Chesapeake Bay watershed

    USGS Publications Warehouse

    Mullinix, C.; Hearn, P.; Zhang, H.; Aguinaldo, J.

    2009-01-01

    Federal, State, and local water quality managers charged with restoring the Chesapeake Bay ecosystem require tools to maximize the impact of their limited resources. To address this need, the U.S. Geological Survey (USGS) and the Environmental Protection Agency's Chesapeake Bay Program (CBP) are developing a suite of Web-based tools called the Chesapeake Online Assessment Support Toolkit (COAST). The goal of COAST is to help CBP partners identify geographic areas where restoration activities would have the greatest effect, select the appropriate management strategies, and improve coordination and prioritization among partners. As part of the COAST suite of tools focused on environmental restoration, a water quality management visualization component called the Nutrient Yields Mapper (NYM) tool is being developed by USGS. The NYM tool is a web application that uses watershed yield estimates from USGS SPAtially Referenced Regressions On Watershed (SPARROW) attributes model (Schwarz et al., 2006) [6] to allow water quality managers to identify important sources of nitrogen and phosphorous within the Chesapeake Bay watershed. The NYM tool utilizes new open source technologies that have become popular in geospatial web development, including components such as OpenLayers and GeoServer. This paper presents examples of water quality data analysis based on nutrient type, source, yield, and area of interest using the NYM tool for the Chesapeake Bay watershed. In addition, we describe examples of map-based techniques for identifying high and low nutrient yield areas; web map engines; and data visualization and data management techniques.

  6. Determining the influence of land-use on urea sources and transport within the Chesapeake Bay watershed

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Urea, a form of organic nitrogen found in fertilizers, manures and septic waste, has increasingly been discovered in surface waters throughout the Chesapeake Bay watershed and similar coastal systems. This nutrient is gaining recognition as a driver for the development of Harmful Algal Blooms (HABs)...

  7. Monitoring of atrazine in the mainstream, major tributaries and streams of the Chesapeake Bay watershed: Ecological significance

    SciTech Connect

    Hall, L.W. Jr.; Anderson, R.D.

    1996-10-01

    The goal of this study was to provide exposure data for the atrazine in the mainstream tributaries of the Chesapeake Bay watershed. In 1995, ten stations were sampled four times per year. Atrazine was also measured at 4 hour intervals for 72 hours at all stream sites during one rain event during the spring. Results are described.

  8. Application of a Structured Decision Process for Informing Watershed Management Options in Guánica Bay, Puerto Rico

    EPA Science Inventory

    The Guánica Bay watershed has been a priority for research, assessment and management since the 1970s, and since 2008, has been the focus of a U.S. Coral Reef Task Force (USCRTF) research initiative involving multiple agencies assembled to address the effect of land management de...

  9. Development of a web-based runoff forecasting tool to guide fertilizer and manure application in the Chesapeake Bay watershed

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Managing the land application of fertilizers and manures is critical to protecting water quality in the Chesapeake Bay watershed. While modern nutrient management tools are designed to help farmers with their long-term field management planning, they do not support daily decisions such as when to a...

  10. Earliest record of the invasive Foraminifera Trochammina hadai in San Francisco Bay, California, USA

    USGS Publications Warehouse

    McGann, Mary

    2014-01-01

    In 1995, Trochammina hadai, a benthic Foraminifera prevalent in Japanese estuaries, was found in San Francisco Bay, California, USA. Subsequent field investigations determined that the species was also present in nearly all of the major ports and estuaries along the western United States. Because of its widespread colonization, it is of interest to determine when T. hadai first appeared as an invasive in the coastal regions of the North Pacific. In San Francisco Bay, the species was not found in 404 surface samples collected between 1930 and 1981. In 1983, however, a grab sediment sample from one of four sites in the southern portion of the bay contained T. hadai. This site was the most northern of the four and contained 12 specimens of the invasive, comprising 1.5% of the assemblage. This is the earliest appearance on record of T. hadai in San Francisco Bay.

  11. USDA-ARS Riesel Watersheds, Riesel, Texas, USA: Water quality research database

    NASA Astrophysics Data System (ADS)

    Harmel, R. Daren; Haney, Richard L.; Smith, Douglas R.; White, Michael; King, Kevin W.

    2014-10-01

    The 75 year legacy database including discharge, sediment loss, land management, and meteorological data for the USDA-ARS Riesel Watersheds, Riesel, TX, USA has been available on the web for more than a decade (www.ars.usda.gov/spa/hydro-data) and used in numerous studies and publications; however, only recently have these data been added to the Sustaining the Earth's Watersheds, Agricultural Research Data System (STEWARDS) database (www.nrrig.mwa.ars.usda.gov/stewards/stewards.html). In addition, water quality data including dissolved inorganic N and P compounds measured from more than 1000 storm runoff events, 1300 base flow sampling events (lateral subsurface return flow or seepage flow), and 157 precipitation events through 2012 were added. The objectives of this manuscript are to present relevant background information on these data, summarize the data collection and analysis methodology, present the measured data along with cursory analyses, and convey the commitment of the USDA-ARS Riesel Watersheds to long-term data accessibility and database enhancement for water quality data and research.

  12. Pyrethroid and organophosphate pesticide-associated toxicity in two coastal watersheds (California, USA).

    PubMed

    Phillips, Bryn M; Anderson, Brian S; Hunt, John W; Siegler, Katie; Voorhees, Jennifer P; Tjeerdema, Ron S; McNeill, Katie

    2012-07-01

    Portions of the Santa Maria River and Oso Flaco Creek watersheds in central California, USA, are listed as impaired under section 303(d) of the Clean Water Act and require development of total maximum daily load (TMDL) allocations. These listings are for general pesticide contamination, but are largely based on historic monitoring of sediment and fish tissue samples that showed contamination by organochlorine pesticides. Recent studies have shown that toxicity in these watersheds is caused by organophosphate pesticides (water and sediment) and pyrethroid pesticides (sediment). The present study was designed to provide information on the temporal and spatial variability of toxicity associated with these pesticides to better inform the TMDL process. Ten stations were sampled in four study areas, one with urban influences, and the remaining in agriculture production areas. Water toxicity was assessed with the water flea Ceriodaphnia dubia, and sediment toxicity was assessed with the amphipod Hyalella azteca. Stations in the lower Santa Maria River had the highest incidence of toxicity, followed by stations influenced by urban inputs. Toxicity identification evaluations and chemical analysis demonstrated that the majority of the observed water toxicity was attributed to organophosphate pesticides, particularly chlorpyrifos, and that sediment toxicity was caused by mixtures of pyrethroid pesticides. The results demonstrate that both agriculture and urban land uses are contributing toxic concentrations of these pesticides to adjacent watersheds, and regional water quality regulators are now using this information to develop management objectives.

  13. Application of spatially referenced regression modeling for the evaluation of total nitrogen loading in the Chesapeake Bay watershed

    USGS Publications Warehouse

    Preston, Stephen D.; Brakebill, John W.

    1999-01-01

    The reduction of stream nutrient loads is an important part of current efforts to improve water quality in the Chesapeake Bay. To design programs that will effectively reduce stream nutrient loading, resource managers need spatially detailed information that describes the location of nutrient sources and the watershed factors that affect delivery of nutrients to the Bay. To address this need, the U.S. Geological Survey has developed a set of spatially referenced regression models for the evaluation of nutrient loading in the watershed. The technique applied for this purpose is referred to as ?SPARROW? (SPAtially Referenced Regressions On Watershed attributes), which is a statistical modeling approach that retains spatial referencing for illustrating predictions, and for relating upstream nutrient sources to downstream nutrient loads. SPARROW is based on a digital stream-network data set that is composed of stream segments (reaches) that are attributed with traveltime and connectivity information. Drainage-basin boundaries are defined for each stream reach in the network data set through the use of a digital elevation model. For the Chesapeake Bay watershed, the spatial network was developed using the U.S. Environmental Protection Agency?s River Reach File 1 digital stream network, and is composed of 1,408 stream reaches and watershed segments. To develop a SPARROW model for total nitrogen in the Chesapeake Bay watershed, data sets for sources and basin characteristics were incorporated into the spatial network and related to stream-loading information by using a nonlinear regression model approach. Total nitrogen source variables that were statistically significant in the model include point sources, urban area, fertilizer application, manure generation and atmospheric deposition. Total nitrogen loss variables that were significant in the model include soil permeability and instream-loss rates for four stream-reach classes. Applications of SPARROW for evaluating

  14. Polychlorinated biphenyl source attribution in Green Bay, Wisconsin, USA, using multivariate similarity among congener profiles in sediment samples.

    PubMed

    Cacela, Dave; Beltman, Douglas J; Lipton, Joshua

    2002-08-01

    Polychlorinated biphenyl (PCB) congener concentrations measured in 1,189 sediment samples from Green Bay (MI/WI, USA), Lake Michigan (MI/WI, USA), and the Fox River (WI, USA) were analyzed statistically to evaluate whether PCB congener profiles in outer Green Bay are more similar to those observed in inner Green Bay or Lake Michigan. Similarities among PCB profiles were assessed with complementary multivariate analysis techniques: Principal component analysis (PCA), cluster analysis, and classification trees. The PCA indicated that profiles in outer Green Bay are distinct from those of inner Green Bay or Lake Michigan but are more similar to those of inner Green Bay. The outer bay profiles are dissimilar to profiles that would result from a simple process of mixing contaminated sediments from the inner bay with Lake Michigan sediments and, therefore, support the conclusion that contaminants in outer Green Bay come from discharges of the Fox River. Several classification trees based on small sets of congener proportions defined simple rules that consistently distinguished the regional profiles. Application of these rules to classify the outer bay samples suggests that the profiles of less than 7% of outer bay samples are similar to Lake Michigan profiles. These results are interpreted with respect to physical transport and chemical weathering processes that may account for the observed differences.

  15. A hydrologic network supporting spatially referenced regression modeling in the Chesapeake Bay watershed

    USGS Publications Warehouse

    Brakebill, J.W.; Preston, S.D.

    2003-01-01

    The U.S. Geological Survey has developed a methodology for statistically relating nutrient sources and land-surface characteristics to nutrient loads of streams. The methodology is referred to as SPAtially Referenced Regressions On Watershed attributes (SPARROW), and relates measured stream nutrient loads to nutrient sources using nonlinear statistical regression models. A spatially detailed digital hydrologic network of stream reaches, stream-reach characteristics such as mean streamflow, water velocity, reach length, and travel time, and their associated watersheds supports the regression models. This network serves as the primary framework for spatially referencing potential nutrient source information such as atmospheric deposition, septic systems, point-sources, land use, land cover, and agricultural sources and land-surface characteristics such as land use, land cover, average-annual precipitation and temperature, slope, and soil permeability. In the Chesapeake Bay watershed that covers parts of Delaware, Maryland, Pennsylvania, New York, Virginia, West Virginia, and Washington D.C., SPARROW was used to generate models estimating loads of total nitrogen and total phosphorus representing 1987 and 1992 land-surface conditions. The 1987 models used a hydrologic network derived from an enhanced version of the U.S. Environmental Protection Agency's digital River Reach File, and course resolution Digital Elevation Models (DEMs). A new hydrologic network was created to support the 1992 models by generating stream reaches representing surface-water pathways defined by flow direction and flow accumulation algorithms from higher resolution DEMs. On a reach-by-reach basis, stream reach characteristics essential to the modeling were transferred to the newly generated pathways or reaches from the enhanced River Reach File used to support the 1987 models. To complete the new network, watersheds for each reach were generated using the direction of surface-water flow derived

  16. Linking Watershed Nitrogen Sources with Nitrogen Dynamics in Rivers of Western Oregon, USA

    NASA Astrophysics Data System (ADS)

    Sobota, D. J.; Compton, J.; Goodwin, K. E.

    2012-12-01

    We constructed contemporary nitrogen (N) budgets for 25 river basins in the Willamette River Basin (WRB) of western Oregon, USA, to improve the understanding of how recent trends in human-driven N loading have influenced riverine N dynamics in the region. Nearly 20% of WRB stream length is currently in fair or poor condition because of high N concentrations. Additionally, nitrate contamination of drinking water affects at least 8,000 people in the WRB. We hypothesized that 1) the majority of N inputs in the WRB would originate from agricultural activities in lowland portions of watersheds, 2) annual riverine N yield (kg/ha/yr) would correspond to annual per area watershed N inputs, and 3) riverine N yields would be seasonal and highest during winter due to the region's Mediterranean climate. We calculated average annual N inputs for each study basin by summing newly available datasets describing spatially explicit N inputs of synthetic fertilizer, atmospheric deposition, crop biological N2 fixation, biological N2 fixation by red alder (Alnus rubra Bong.), livestock manure, and point sources for the period 1996 - 2007. Annual and seasonal riverine N exports were estimated with the USGS model LOADEST calibrated to N concentration data collected during the study period. We estimated that two-thirds of total N input to the WRB study basins in the 2000s came from synthetic fertilizer application. Nearly all fertilizer application occurred on the lowlands near watershed mouths. We found a wide range of riverine N yields from the study basins, ranging from one to 70 kg N/ha/yr. Across the study basins, N export was more strongly correlated to fertilizer application rates than to percent of agricultural area in the watershed. Low watershed N yields reflected a high proportion of watershed area in the forested Cascade Mountain Range, which received low N inputs mainly from atmospheric deposition. N yields from study basins were strongly seasonal, with at least 50%, and

  17. Factors affecting herbicide yields in the Chesapeake Bay watershed, June 1994

    USGS Publications Warehouse

    Hainly, R.A.; Kahn, J.M.

    1996-01-01

    Median concentrations and instantaneous yields of alachlor, metolachlor, atrazine, cyanazine, and simazine were generally highest at sites in the Lower Susquehanna River Basin and in agricultural subbasins. Instantaneous herbicide yields are related to land use, hydrogeologic setting, streamflow yield, and agricultural row cropping practices. The significance of these relations may be affected by the interdependence of the factors. The percentage of basin area planted in corn is the most influential factor in the prediction of herbicide yield. Instantaneous yields of all five herbicides measured in June 1994 related poorly to averaged 199094 herbicide use. Annually averaged herbicide-use data are too general to use as a predictor for short-term herbicide yields. An evaluation of factors affecting herbicide yields could be refined with more-current land use and land cover information and a more accurate estimate of the percentage of basin area planted in corn. Factors related to herbicide yields can be used to predict herbicide yields in other basins within the Chesapeake Bay watershed and to develop an estimate of herbicide loads to Chesapeake Bay.Median concentrations and instantaneous yields of alachlor, metolachlor, atrazine, cyanazine, and simazine were generally highest at sites in the Lower Susquehanna River Basin and in agricultural subbasins. Instantaneous herbicide yields are related to land use, hydrogeologic setting, streamflow yield, and agricultural row cropping practices. The significance of these relations may be affected by the interdependence of the factors. The percentage of basin area planted in corn is the most influential factor in the prediction of herbicide yield. Instantaneous yields of all five herbicides measured in June 1994 related poorly to averaged 1990-94 herbicide use. Annually averaged herbicide-use data are too general to use as a predictor for short-term herbicide yields. An evaluation of factors affecting herbicide yields could

  18. Water quality mapping of Laguna de Bay and its watershed, Philippines

    NASA Astrophysics Data System (ADS)

    Saito, S.; Nakano, T.; Shin, K.; Maruyama, S.; Miyakawa, C.; Yaota, K.; Kada, R.

    2011-12-01

    Laguna de Bay (or Laguna Lake) is the largest lake in the Philippines, with a surface area of 900 km2 and its watershed area of 2920 km2 (Santos-Borja, 2005). It is located on the southwest part of the Luzon Island and its watershed contains 5 provinces, 49 municipalities and 12 cities, including parts of Metropolitan Manila. The water quality in Laguna de Bay has significantly deteriorated due to pollution from soil erosion, effluents from chemical industries, and household discharges. In this study, we performed multiple element analysis of water samples in the lake and its watersheds for chemical mapping, which allows us to evaluate the regional distribution of elements including toxic heavy metals such as Cd, Pb and As. We collected water samples from 24 locations in Laguna de Bay and 160 locations from rivers in the watersheds. The sampling sites of river are mainly downstreams around the lake, which covers from urbanized areas to rural areas. We also collected well water samples from 17 locations, spring water samples from 10 locations, and tap water samples from 21 locations in order to compare their data with the river and lake samples and to assess the quality of household use waters. The samples were collected in dry season of the study area (March 13 - 17 and May 2 - 9, 2011). The analysis was performed at the Research Institute for Humanity and Nature (RIHN), Japan. The concentrations of the major components (Cl, NO3, SO4, Ca, Mg, Na, and K) dissolved in the samples were determined with ion chromatograph (Dionex Corporation ICS-3000). We also analyzed major and trace elements (Li, B, Na, Mg, Al, Si, P, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn Ga, Ge, As, Se, Rb, Sr, Y, Zr, Mo, Ag, Cd, Sn, Sb, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, W, Pb and U) with inductively coupled plasma-mass spectrometry (ICP-MS, Agilent Technologies 7500cx). The element concentrations of rivers are characterized by remarkable regional variations. For

  19. Development of Land Segmentation, Stream-Reach Network, and Watersheds in Support of Hydrological Simulation Program-Fortran (HSPF) Modeling, Chesapeake Bay Watershed, and Adjacent Parts of Maryland, Delaware, and Virginia

    USGS Publications Warehouse

    Martucci, Sarah K.; Krstolic, Jennifer L.; Raffensperger, Jeff P.; Hopkins, Katherine J.

    2006-01-01

    The U.S. Geological Survey, U.S. Environmental Protection Agency Chesapeake Bay Program Office, Interstate Commission on the Potomac River Basin, Maryland Department of the Environment, Virginia Department of Conservation and Recreation, Virginia Department of Environmental Quality, and the University of Maryland Center for Environmental Science are collaborating on the Chesapeake Bay Regional Watershed Model, using Hydrological Simulation Program - FORTRAN to simulate streamflow and concentrations and loads of nutrients and sediment to Chesapeake Bay. The model will be used to provide information for resource managers. In order to establish a framework for model simulation, digital spatial datasets were created defining the discretization of the model region (including the Chesapeake Bay watershed, as well as the adjacent parts of Maryland, Delaware, and Virginia outside the watershed) into land segments, a stream-reach network, and associated watersheds. Land segmentation was based on county boundaries represented by a 1:100,000-scale digital dataset. Fifty of the 254 counties and incorporated cities in the model region were divided on the basis of physiography and topography, producing a total of 309 land segments. The stream-reach network for the Chesapeake Bay watershed part of the model region was based on the U.S. Geological Survey Chesapeake Bay SPARROW (SPAtially Referenced Regressions On Watershed attributes) model stream-reach network. Because that network was created only for the Chesapeake Bay watershed, the rest of the model region uses a 1:500,000-scale stream-reach network. Streams with mean annual streamflow of less than 100 cubic feet per second were excluded based on attributes from the dataset. Additional changes were made to enhance the data and to allow for inclusion of stream reaches with monitoring data that were not part of the original network. Thirty-meter-resolution Digital Elevation Model data were used to delineate watersheds for each

  20. Classification of High Spatial Resolution, Hyperspectral Remote Sensing Imagery of the Little Miami River Watershed in Southwest Ohio, USA (Final)

    EPA Science Inventory

    EPA announced the availability of the final report,Watershed in Southwest Ohio, USA . This report and associated land use/land cover (LULC) coverage is the result o...

  1. CLASSIFICATION OF HIGH SPATIAL RESOLUTION, HYPERSPECTRAL REMOTE SENSING IMAGERY OF THE LITTLE MIAMI RIVER WATERSHED IN SOUTHWEST OHIO, USA (FINAL)

    EPA Science Inventory

    The document and associated land use/land cover (LULC) coverage, entitled Classification of High Spatial Resolution, Hyperspectral Remote Sensing Imagery of the Little Miami River Watershed in Southwest Ohio, USA, is the result of a collaborative effort among an interdisci...

  2. Proceedings of the workshop on alternative futures—Accounting for growth in the Chesapeake Bay watershed

    USGS Publications Warehouse

    Claggett, Peter; Thompson, Renee

    2012-01-01

    This workshop provided a forum for identifying and discussing policies and assumptions for use in creating regionally consistent alternative future land-use scenarios. The alternative scenarios will help to inform how planning can potentially be used as a primary Best Management Practice by identifying land-use policies and other planning actions that can be taken to minimize future increases in nutrients and sediments associated with the spatial pattern and intensity of land development. The Chesapeake Bay Program Office will run these scenarios through the watershed model to quantify the differences in loadings achieved through implementation of land-use policies and to help assess the uncertainty associated with the current trend forecast. In addition, the outcomes of this workshop can assist jurisdictions in planning for growth with respect to minimizing future increases in nutrient and sediment associated with land development. Ultimately, this workshop was intended to provide jurisdictions with information that can be used to better account for refinement of their Watershed Implementation Plans.

  3. [Variations of annual load of TN and TP in the deep bay watershed, Shenzhen].

    PubMed

    Zhao, Chen-Chen; Zhang, Shi-Yan; Mao, Xian-Zhong

    2014-11-01

    The empirical coefficient of sewage disposal, export coefficient model and mean concentration method were respectively used to estimate variations of annual load TN and TP from Shenzhen and Hong Kong areas in the Deep Bay Watershed from 1986 to 2011. The results showed that, the annual average loads of TN and TP were 10 388.2 t, 10 727.9 t, 10 937.3 t, and 2 694.5 t, 1 929.2 t, 1388.7 t, respectively in the whole watershed during three periods, 80s, 90s and years after 2000. With the rapid development of society, economy and the urbanization, annual pollution loading of TN and TP in Shenzhen area showed an obviously increase, 4373.6 t and 195.9 t, by 261.0% and 64.2% for point source, and 1067.2 t and 151.0 t, by 63.4% and 84.9% for non-point source, respectively. Non-point source with high pollution load was mainly caused by the expanding of land for construction and roads. The contribution ratios of TN and TP from Shenzhen area increased from 42.4% and 27.0% to 85.1% and 75.2%. Annual loads of TN and TP in Hong Kong area decreased 3 028.5 t and 1 031.5 t, by 66.3% and 79.0% reduced.

  4. An analysis of urban development and its environmental impact on the Tampa Bay watershed

    USGS Publications Warehouse

    Xian, G.; Crane, M.; Su, J.

    2007-01-01

    Urbanization has transformed natural landscapes into anthropogenic impervious surfaces. Urban land use has become a major driving force for land cover and land use change in the Tampa Bay watershed of west-central Florida. This study investigates urban land use change and its impact on the watershed. The spatial and temporal changes, as well as the development density of urban land use are determined by analyzing the impervious surface distribution using Landsat satellite imagery. Population distribution and density are extracted from the 2000 census data. Non-point source pollution parameters used for measuring water quality are analyzed for the sub-drainage basins of Hillsborough County. The relationships between 2002 urban land use, population distribution and their environmental influences are explored using regression analysis against various non-point source pollutant loadings in these sub-drainage basins. The results suggest that strong associations existed between most pollutant loadings and the extent of impervious surface within each sub-drainage basin in 2002. Population density also exhibits apparent correlations with loading rates of several pollutants. Spatial variations of selected non-point source pollutant loadings are also assessed. ?? 2006 Elsevier Ltd. All rights reserved.

  5. Sources of suspended-sediment flux in streams of the chesapeake bay watershed: A regional application of the sparrow model

    USGS Publications Warehouse

    Brakebill, J.W.; Ator, S.W.; Schwarz, G.E.

    2010-01-01

    We describe the sources and transport of fluvial suspended sediment in nontidal streams of the Chesapeake Bay watershed and vicinity. We applied SPAtially Referenced Regressions on Watershed attributes, which spatially correlates estimated mean annual flux of suspended sediment in nontidal streams with sources of suspended sediment and transport factors. According to our model, urban development generates on average the greatest amount of suspended sediment per unit area (3,928 Mg/km2/year), although agriculture is much more widespread and is the greatest overall source of suspended sediment (57 Mg/km2/year). Factors affecting sediment transport from uplands to streams include mean basin slope, reservoirs, physiography, and soil permeability. On average, 59% of upland suspended sediment generated is temporarily stored along large rivers draining the Coastal Plain or in reservoirs throughout the watershed. Applying erosion and sediment controls from agriculture and urban development in areas of the northern Piedmont close to the upper Bay, where the combined effects of watershed characteristics on sediment transport have the greatest influence may be most helpful in mitigating sedimentation in the bay and its tributaries. Stream restoration efforts addressing floodplain and bank stabilization and incision may be more effective in smaller, headwater streams outside of the Coastal Plain. ?? 2010 American Water Resources Association. No claim to original U.S. government works.

  6. Contaminants in sediment, food-chain biota, and bird eggs from the Newport Bay watershed, Orange County, California.

    PubMed

    Santolo, Gary M; Byron, Earl R; Ohlendorf, Harry M

    2016-02-01

    Groundwater-related discharges in the San Diego Creek/Newport Bay watershed in Orange County, California have the potential to adversely affect the surface waters within the watershed and would likely not comply with the established total maximum daily loads (TMDLs) for the watershed. In 2004 and 2005, we studied the concentrations of contaminants of TMDL concern (particularly selenium [Se]) in birds that are at risk of exposure to contaminated food items because they feed and nest in the Newport Bay watershed. Most bioaccumulation is from elevated Se in groundwater downstream of a historic terminal swamp. Se bioaccumulation was observed in all biota tested, and DDE was found in fish and bird egg samples. Effects of contaminants on fish and birds are inconclusive due to the management disturbances in the watershed (e.g., flood control) and lack of bird nesting habitat. Although a significant relationship was observed between DDE concentrations and eggshell thinning in American avocet (Recurvirostra americana) eggs, the shell thinning in avocet and other species examined was not enough to result in hatching failure. Further focused monitoring efforts will be needed to characterize the exposure and risk levels.

  7. Summary of Optical-Backscatter and Suspended-Sediment Data, Tomales Bay Watershed, California, Water Years 2004, 2005, and 2006

    USGS Publications Warehouse

    Curtis, Jennifer A.

    2007-01-01

    The U.S. Geological Survey, in cooperation with Point Reyes National Seashore, is studying suspended-sediment transport dynamics in the two primary tributaries to Tomales Bay, Lagunitas Creek and Walker Creek. Suspended-sediment samples and continuous optical backscatter (turbidity) data were collected at three locations during water years 2004?06 (October 1, 2003?September 30, 2006): at two sites in the Lagunitas Creek watershed and at one site in the Walker Creek watershed. Sediment samples were analyzed for suspended-sediment concentration, grain size, and turbidity. Data were used to estimate mean daily and annual seasonal suspended-sediment discharge, which were published in U.S. Geological Survey Annual Water-Data Reports. Data were utilized further in this report to develop field-based optical-backscatter calibration equations, which then were used to derive a continuous time series (15-minute interval) of suspended-sediment concentrations. Sensor fouling and aggradation of the channel bed occurred periodically throughout the project period, resulting in data loss. Although periods of data loss occurred, collection of optical sensor data improved our understanding of suspended-sediment dynamics in the Lagunitas Creek and Walker Creek watersheds by providing continuous time-series storm event data that were analyzed to determine durations of elevated sediment concentrations (periods of time when suspended-sediment concentration was greater than 100 mg/L). Data derived from this project contributed baseline suspended-sediment transport information that will be used to develop and implement sediment total maximum daily loads for Tomales Bay and its tributary watersheds, and provides supporting information for additional total maximum daily loads (pathogens, nutrients, and mercury) and restoration efforts for four federally listed aquatic species that are affected directly by sediment loading in the Tomales Bay watershed. In addition, this project provided an

  8. A COMPARISON OF THE SALINITY REGIME ALONG THE TEXAS COAST WITH TERRESTRIAL VEGETATION GREENNESS AND WATER USE IN THE GALVESTON BAY WATERSHED USING REMOTING SENSING

    EPA Science Inventory

    Variability in vegetation greenness was determined for the Galveston Bay watershed using biweekly Normalized Difference Vegetation Index (NDVI) data derived from the Advanced Very High Resolution Radiometer (A VHRR) flown on NOAA satellites. NDVI variability was compared with reg...

  9. Benthic macrofauna habitat associations in Willapa Bay, Washington, USA

    NASA Astrophysics Data System (ADS)

    Ferraro, Steven P.; Cole, Faith A.

    2007-02-01

    Estuary-wide benthic macrofauna-habitat associations in Willapa Bay, Washington, United States, were determined for 4 habitats (eelgrass [ Zostera marina], Atlantic cordgrass [ Spartina alterniflora], mud shrimp [ Upogebia pugettensis], ghost shrimp [ Neotrypaea californiensis]) in 1996 and 7 habitats (eelgrass, Atlantic cordgrass, mud shrimp, ghost shrimp, oyster [ Crassostrea gigas], bare mud/sand, subtidal) in 1998. Most benthic macrofaunal species inhabited multiple habitats; however, 2 dominants, a fanworm, Manayunkia aestuarina, in Spartina, and a sand dollar, Dendraster excentricus, in subtidal, were rare or absent in all other habitats. Benthic macrofaunal Bray-Curtis similarity varied among all habitats except eelgrass and oyster. There were significant differences among habitats within- and between-years on several of the following ecological indicators: mean number of species ( S), abundance ( A), biomass ( B), abundance of deposit (AD), suspension (AS), and facultative (AF) feeders, Swartz's index (SI), Brillouin's index ( H), and jackknife estimates of habitat species richness (HSR). In the 4 habitats sampled in both years, A was about 2.5× greater in 1996 (a La Niña year) than 1998 (a strong El Niño year) yet relative values of S, A, B, AD, AS, SI, and H among the habitats were not significantly different, indicating strong benthic macrofauna-habitat associations despite considerable climatic and environmental variability. In general, the rank order of habitats on indicators associated with high diversity and productivity (high S, A, B, SI, H, HSR) was eelgrass = oyster ≥ Atlantic cordgrass ≥ mud shrimp ≥ bare mud/sand ≥ ghost shrimp = subtidal. Vegetation, burrowing shrimp, and oyster density and sediment %silt + clay and %total organic carbon were generally poor, temporally inconsistent predictors of ecological indicator variability within habitats. The benthic macrofauna-habitat associations in this study can be used to help identify

  10. Watershed and Hydrodynamic Modeling for Evaluating the Impact of Land Use Change on Submerged Aquatic Vegetation and Seagrasses in Mobile Bay

    NASA Technical Reports Server (NTRS)

    Estes, Maurice G.; Al-Hamdan, Mohammed; Thom, Ron; Quattrochi, Dale; Woodruff, Dana; Judd, Chaeli; Ellism Jean; Watson, Brian; Rodriguez, Hugo; Johnson, Hoyt

    2009-01-01

    There is a continued need to understand how human activities along the northern Gulf of Mexico coast are impacting the natural ecosystems. The gulf coast is experiencing rapid population growth and associated land cover/land use change. Mobile Bay, AL is a designated pilot region of the Gulf of Mexico Alliance (GOMA) and is the focus area of many current NASA and NOAA studies, for example. This is a critical region, both ecologically and economically to the entire United States because it has the fourth largest freshwater inflow in the continental USA, is a vital nursery habitat for commercially and recreational important fisheries, and houses a working waterfront and port that is expanding. Watershed and hydrodynamic modeling has been performed for Mobile Bay to evaluate the impact of land use change in Mobile and Baldwin counties on the aquatic ecosystem. Watershed modeling using the Loading Simulation Package in C++ (LSPC) was performed for all watersheds contiguous to Mobile Bay for land use Scenarios in 1948, 1992, 2001, and 2030. The Prescott Spatial Growth Model was used to project the 2030 land use scenario based on observed trends. All land use scenarios were developed to a common land classification system developed by merging the 1992 and 2001 National Land Cover Data (NLCD). The LSPC model output provides changes in flow, temperature, sediments and general water quality for 22 discharge points into the Bay. These results were inputted in the Environmental Fluid Dynamics Computer Code (EFDC) hydrodynamic model to generate data on changes in temperature, salinity, and sediment concentrations on a grid with four vertical profiles throughout the Bay s aquatic ecosystems. The models were calibrated using in-situ data collected at sampling stations in and around Mobile bay. This phase of the project has focused on sediment modeling because of its significant influence on light attenuation which is a critical factor in the health of submerged aquatic

  11. Downscaling future climate projections to the watershed scale: a north San Francisco Bay estuary case study

    USGS Publications Warehouse

    Micheli, Elisabeth; Flint, Lorraine; Flint, Alan; Weiss, Stuart; Kennedy, Morgan

    2012-01-01

    We modeled the hydrology of basins draining into the northern portion of the San Francisco Bay Estuary (North San Pablo Bay) using a regional water balance model (Basin Characterization Model; BCM) to estimate potential effects of climate change at the watershed scale. The BCM calculates water balance components, including runoff, recharge, evapotranspiration, soil moisture, and stream flow, based on climate, topography, soils and underlying geology, and the solar-driven energy balance. We downscaled historical and projected precipitation and air temperature values derived from weather stations and global General Circulation Models (GCMs) to a spatial scale of 270 m. We then used the BCM to estimate hydrologic response to climate change for four scenarios spanning this century (2000–2100). Historical climate patterns show that Marin’s coastal regions are typically on the order of 2 °C cooler and receive five percent more precipitation compared to the inland valleys of Sonoma and Napa because of marine influences and local topography. By the last 30 years of this century, North Bay scenarios project average minimum temperatures to increase by 1.0 °C to 3.1 °C and average maximum temperatures to increase by 2.1 °C to 3.4 °C (in comparison to conditions experienced over the last 30 years, 1981–2010). Precipitation projections for the 21st century vary between GCMs (ranging from 2 to 15% wetter than the 20th-century average). Temperature forcing increases the variability of modeled runoff, recharge, and stream discharge, and shifts hydrologic cycle timing. For both high- and low-rainfall scenarios, by the close of this century warming is projected to amplify late-season climatic water deficit (a measure of drought stress on soils) by 8% to 21%. Hydrologic variability within a single river basin demonstrated at the scale of subwatersheds may prove an important consideration for water managers in the face of climate change. Our results suggest that in arid

  12. Development, calibration, and analysis of a hydrologic and water-quality model of the Delaware Inland Bays watershed

    USGS Publications Warehouse

    Gutierrez-Magness, Angelica L.; Raffensperger, Jeffrey Peter

    2003-01-01

    Excessive nutrients and sediment are among the most significant environmental stressors in the Delaware Inland Bays (Rehoboth, Indian River, and Little Assawoman Bays). Sources of nutrients, sediment, and other contaminants within the Inland Bays watershed include point-source discharges from industries and wastewater-treatment plants, runoff and infiltration to ground water from agricultural fields and poultry operations, effluent from on-site wastewater disposal systems, and atmospheric deposition. To determine the most effective restoration methods for the Inland Bays, it is necessary to understand the relative distribution and contribution of each of the possible sources of nutrients, sediment, and other contaminants. A cooperative study involving the Delaware Department of Natural Resources and Environmental Control, the Delaware Geological Survey, and the U.S. Geological Survey was initiated in 2000 to develop a hydrologic and water-quality model of the Delaware Inland Bays watershed that can be used as a water-resources planning and management tool. The model code Hydrological Simulation Program - FORTRAN (HSPF) was used. The 719-square-kilometer watershed was divided into 45 model segments, and the model was calibrated using streamflow and water-quality data for January 1999 through April 2000 from six U.S. Geological Survey stream-gaging stations within the watershed. Calibration for some parameters was accomplished using PEST, a model-independent parameter estimator. Model parameters were adjusted systematically so that the discrepancies between the simulated values and the corresponding observations were minimized. Modeling results indicate that soil and aquifer permeability, ditching, dominant land-use class, and land-use practices affect the amount of runoff, the mechanism or flow path (surface flow, interflow, or base flow), and the loads of sediment and nutrients. In general, the edge-of-stream total suspended solids yields in the Inland Bays

  13. Sulfate exports from multiple catchments in a glaciated forested watershed in western New York, USA.

    PubMed

    Inamdar, Shreeram P; Mitchell, Myron J

    2008-04-01

    Sulfate (SO4(2-)) concentrations and fluxes were studied for multiple storm events in the Point Peter Brook watershed, a glaciated, forested watershed located in Western New York, USA. Investigations were performed across one large (696 ha) and three small (1.6-3.4 ha) catchments with varying extent of riparian and wetland areas. Concentrations of SO4(2-) in groundwater sources (mean values: 238-910 micromol(c) L(-1)) were considerably greater than concentrations recorded for rainfall (60 micromol(c) L(-1)) and throughfall (72-129 micromol(c) L(-1)). Seasonality in SO4(2-) concentrations was most pronounced for valley-bottom riparian waters with maximum concentrations in late winter-spring (February-March) and a minimum in late summer (August). Concentrations of SO4(2-) in wetland water were considerably less than riparian water indicating the likelihood of SO4(2-) reduction in anoxic wetland conditions. Storm events displayed a dilution pattern in SO4(2-) concentrations with a minimum coinciding with the maximum in throughfall contributions. End member mixing analysis (EMMA) was able to predict the storm event concentrations of SO4(2-) for four of the six comparisons. Concentrations of SO4(2-) at the outlet of the large (696 ha) catchment were much greater than values recorded for the smaller catchments. Exports of SO4(2-) in streamflow exceeded the inputs from atmospheric deposition suggesting that watersheds like Point Peter Brook may not show any immediate response to decreases in atmospheric SO4(2-) deposition.

  14. Characterization of the shallow groundwater system in an alpine watershed: Handcart Gulch, Colorado, USA

    USGS Publications Warehouse

    Kahn, K.G.; Ge, S.; Caine, J.S.; Manning, A.

    2008-01-01

    Water-table elevation measurements and aquifer parameter estimates are rare in alpine settings because few wells exist in these environments. Alpine groundwater systems may be a primary source of recharge to regional groundwater flow systems. Handcart Gulch is an alpine watershed in Colorado, USA comprised of highly fractured Proterozoic metamorphic and igneous rocks with wells completed to various depths. Primary study objectives include determining hydrologic properties of shallow bedrock and surficial materials, developing a watershed water budget, and testing the consistency of measured hydrologic properties and water budget by constructing a simple model incorporating groundwater and surface water for water year 2005. Water enters the study area as precipitation and exits as discharge in the trunk stream or potential recharge for the deeper aquifer. Surficial infiltration rates ranged from 0.1-6.2??0-5 m/s. Discharge was estimated at 1.28??10-3 km3. Numerical modeling analysis of single-well aquifer tests predicted lower specific storage in crystalline bedrock than in ferricrete and colluvial material (6.7??10-5-2.10??0-3 l/m). Hydraulic conductivity in crystalline bedrock was significantly lower than in colluvial and alluvial material (4.3??10-9 -2.0??10-4 m/s). Water budget results suggest that during normal precipitation and temperatures water is available to recharge the deeper groundwater flow system. ?? Springer-Verlag 2007.

  15. The contribution of wetlands to stream nitrogen load in the Loch Vale Watershed, Colorado, USA

    USGS Publications Warehouse

    Jian-hui, Huang; Baron, Jill; Binkley, Dan

    1996-01-01

    We explored the difference between the concentrations of different N forms and other chemical properties between stream water and riparian zone wetland soil water in the Loch Vale Watershed which is located on the eastern slope of the Continental Divide in Rocky Mountain National Park, Colorado, USA. The nitrate N concentration in stream water were significantly higher than in soil water of the three wetlands, while no significant difference appeared in ammonium N. The pH values were higher and conductivity values were lower in stream water than in wetland soil water. However, significant difference also appeared between nitrate N concentrations, pH and conductivity values in the water sampled from different positions of streams. The stream tributary water had higher nitrate N concentrations, higher pH and higher conducitity values. We also conducted experiments to compare the difference between the productivity, total N concentrations in biomass and soil of upper layers. At the end, we concluded that the wetlands distributed along the streams in Loch Vale Watershed had little effect on the nitrogen load of the stream water there.

  16. Mercury concentrations in tidal marsh sparrows and their use as bioindicators in Delaware Bay, USA.

    PubMed

    Warner, Sarah E; Shriver, W Gregory; Pepper, Margaret A; Taylor, Robert J

    2010-12-01

    Mercury (Hg) contamination from industrial sources is pervasive throughout North America and is recognized by the US Environmental Protection Agency as a health hazard for wildlife and humans. Avian species are commonly used as bioindicators of Hg because they are sensitive to contaminants in the environment and are relatively easy to sample. However, it is important to select the appropriate avian species to use as a bioindicator, which should be directly related to the project objectives. In this study, we tested the utility of two tidal marsh sparrows, Seaside (Ammodramus maritimus) and Saltmarsh (Ammodramus caudacutus) sparrows, as bioindicator species of the extent of Hg contamination in tidal marshes along the Delaware Bay. To determine the possibility of using one or both of these species, we estimated sparrow blood Hg burden in five Delaware watersheds. We found no difference in Hg concentrations between species (F (1,133) < 0.01, P=0.99), but Saltmarsh Sparrows had limited sample size from each site and were, therefore, not appropriate for a Delaware Bay-wide Hg indicator. Seaside Sparrows, however, were abundant and relatively easy to sample in the five watersheds. Seaside Sparrow blood Hg levels ranged from 0.15 to 2.12 ppm, differed among drainages, and were greatest in two drainages distant from the Delaware Bay shoreline (F (4,95) =2.51, P=0.05). Based on a power analysis for Seaside Sparrow blood Hg, we estimated that 16 samples would be necessary to detect differences among sites. Based on these data, we propose that Seaside Sparrows may be used as a tidal marsh Hg bioindicator species given their habitat specificity, relative abundance, widespread distribution in marsh habitats, ease of sampling, and limited variation in blood Hg estimates within a sampling area. In Delaware Bay, Saltmarsh Sparrows may be too rare (making them difficult to sample) to be a viable tidal marsh Hg bioindicator.

  17. Linking ecosystem service supply to stakeholder concerns on both land and sea: An example from Guánica Bay watershed, Puerto Rico

    EPA Science Inventory

    Policies to protect coastal resources may lead to greater social, economic, and ecological returns when they consider potential co-benefits and trade-offs on land. In Guánica Bay watershed, Puerto Rico, a watershed management plan is being implemented to restore declining ...

  18. Reconstructing the natural hydrology of the San Francisco Bay-Delta watershed

    NASA Astrophysics Data System (ADS)

    Fox, P.; Hutton, P. H.; Howes, D. J.; Draper, A. J.; Sears, L.

    2015-04-01

    The San Francisco Estuary, composed of San Francisco Bay and the Sacramento-San Joaquin River Delta, is the largest estuary along the Pacific coast of the United States. The tributary watersheds of California's Central Valley are the principal sources of freshwater flow into the San Francisco Bay-Delta estuary. The Delta serves as one of the principal hubs of California's water system, which delivers 45% of the water used statewide to 25 million residents and 16 000 km2 of farmland. The development of California, from small-scale human settlements that co-existed with an environment rich in native vegetation to the eighth largest economy in the world was facilitated by reconfiguring the state's water resources to serve new uses: agriculture, industry, and a burgeoning population. The redistribution of water from native vegetation to other uses was accompanied by significant declines in native aquatic species that rely on the San Francisco Bay-Delta system. These declines have been attributed to a variety of causes, including reduction in the amount of freshwater reaching the San Francisco Bay-Delta watershed (Delta outflow); decreased sediment loads; increased nutrient loads; changes in nutrient stoichiometry; contaminants; introduced species; habitat degradation and loss; and shifts in the ocean-atmosphere system, among others. Among these stressors, only the volume of Delta outflow has been regulated in an effort to address the decline in aquatic species. As native species evolved under natural landscape conditions, prior to European settlement in the mid-18th century, we evaluated the impact of landscape changes on the amount of Delta outflow. We reconstructed the natural landscape and used water balances to estimate the long-term annual average Delta outflow that would have occurred under natural landscape conditions if the climate from 1922 to 2009 were to repeat. These outflows are referred to as "natural" Delta outflows and are the first reported estimate of

  19. Occurrence of IRGAROL 1051 in coastal waters from Biscayne Bay, Florida, USA.

    PubMed

    Gardinali, Piero R; Plasencia, Manolo; Mack, Steve; Poppell, Charles

    2002-08-01

    Surface water samples from marinas, commercial ports and open bay areas collected from Biscayne Bay and the Miami River, Florida, USA, were analyzed for the occurrence of IRGAROL 1051 by GC/MS. The anifouling boosting herbicide was found in 80% (46/57) of the samples collected between March 1999 and September 2000. Concentrations within the bay range between non-detected (<1 ppt) and 61 ppt (ng/L) and were generally low compared with levels reported in European or Japanese waters. Aside from the elevated concentrations observed along the Miami River South Fork (61 ppt), the highest concentrations observed in the bay corresponded to marinas with high density of pleasure craft and restricted water circulation. In contrast, occurrence of IRGAROL 1051 along the commercial port or the cruise line terminal was generally lower (<1-2.2 ppt). Concentrations around Coconut Grove Marina were consistently higher (5-12 ppt) than the rest of the bay waters during the whole period of time surveyed.

  20. Ecosystem under pressure: ballast water discharge into Galveston Bay, Texas (USA) from 2005 to 2010.

    PubMed

    Steichen, Jamie L; Windham, Rachel; Brinkmeyer, Robin; Quigg, Antonietta

    2012-04-01

    Ballast water exchange processes facilitate the dispersal and unnatural geographic expansion of phytoplankton, including harmful algal bloom species. From 2005 to 2010, over 45,000 vessels (≈ 8000 annually) travelled across Galveston Bay (Texas, USA) to the deep-water ports of Houston (10th largest in the world), Texas City and Galveston. These vessels (primarily tankers and bulkers) discharged ≈ 1.2 × 10(8) metrictons of ballast water; equivalent to ≈ 3.4% of the total volume of the Bay. Over half of the ballast water discharged had a coastwise origin, 96% being from US waters. Galveston Bay has fewer non-indigenous species but receives a higher volume of ballast water discharge, relative to the highly invaded Chesapeake and San Francisco Bays. Given the magnitude of shipping traffic, the role of Galveston Bay, both as a recipient and donor region of non-indigenous phytoplankton species is discussed here in terms of the invasibility risk to this system by way of ballast water.

  1. Sources, fate, and transport of nitrogen and phosphorus in the Chesapeake Bay watershed-An empirical model

    USGS Publications Warehouse

    Ator, Scott W.; Brakebill, John W.; Blomquist, Joel D.

    2011-01-01

    Nutrient fate and transport through the Chesapeake Bay watershed to the bay reflect the diferent physical and chemical properties of nitrogen and phosphorus compounds. Groundwater is an important pathway for nitrogen transport (as nitrate), and TN flux is greatest in areas with greater groundwater flow and in areas of the Piedmont underlain by carbonate rocks. TN flux decreases with increasing vegetative growth (likely indicative of plant uptake) and soil available water capacity (likely indicative of reducing conditions). Phosphorus transport to streams, conversely, is greatest in areas most likely to generate overland runoff and related erosion, including those with less permeable and more erodible soils and greater precipitation. Phosphorus transport also is greater in the Coastal Plain than in other areas, possibly due to saturation of soils with historical phosphorus applications. Both nitrogen and phosphorus are lost within watershed impoundments (lakes, ponds, or reservoirs), and nitrogen is also lost significantly along flowing reaches, particularly in small streams and in larger streams in warmer areas.

  2. Long-term Watershed Database for the Ridge and Valley Physiographic Province: Mahantango Creek Watershed, Pennsylvania, USA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Understanding agricultural effects on water quality in rivers and estuaries requires understanding of hydrometeorology and geochemical cycling at various scales over time. The USDA-ARS initiated a hydrologic research program at the Mahantango Creek Watershed (MCW) in 1968, a research watershed at t...

  3. Islands at bay: Rising seas, eroding islands, and waterbird habitat loss in Chesapeake Bay (USA)

    USGS Publications Warehouse

    Erwin, R.M.; Brinker, D.F.; Watts, B.D.; Costanzo, G.R.; Morton, D.D.

    2011-01-01

    Like many resources in the Chesapeake Bay region of the U. S., many waterbird nesting populations have suffered over the past three to four decades. In this study, historic information for the entire Bay and recent results from the Tangier Sound region were evaluated to illustrate patterns of island erosion and habitat loss for 19 breeding species of waterbirds. Aerial imagery and field data collected in the nesting season were the primary sources of data. From 1993/1994 to 2007/2008, a group of 15 islands in Tangier Sound, Virginia were reduced by 21% in area, as most of their small dunes and associated vegetation and forest cover were lost to increased washovers. Concurrently, nesting American black ducks (Anas rubripes) declined by 66%, wading birds (herons-egrets) by 51%, gulls by 72%, common terns (Sterna hirundo) by 96% and black skimmers (Rynchops niger) by about 70% in this complex. The declines noted at the larger Bay-wide scale suggest that this study area maybe symptomatic of a systemic limitation of nesting habitat for these species. The island losses noted in the Chesapeake have also been noted in other Atlantic U. S. coastal states. Stabilization and/or restoration of at least some of the rapidly eroding islands at key coastal areas are critical to help sustain waterbird communities. ?? 2010 US Government.

  4. Mortality and herpesvirus infections of the Pacific oyster Crassostrea gigas in Tomales Bay, California, USA.

    PubMed

    Burge, Colleen A; Griffin, Frederick J; Friedman, Carolyn S

    2006-09-14

    Seed losses of Pacific oysters Crassostrea gigas have been associated with an ostreid herpesvirus-1 (OsHV-1) in Europe, and in 2002, a similar OsHV was detected in Tomales Bay, California, USA. In May of 2003, 5 stocks of seed Pacific oysters were planted at 2 sites (Inner Bay and Outer Bay) in Tomales Bay and monitored for mortality, presence/prevalence of OsHV (using polymerase chain reaction [PCR] and histology), and growth. Temperature (degrees C) and salinity data were collected every half an hour at each site. OsHV was detected at both the Inner and Outer Bay sites on the same sample date and mean temperature predicted OsHV presence (p < 0.005). High levels of mortality occurred 2 wk (Inner Bay site) and 4 wk (Outer Bay site) after OsHV detection. OsHV presence predicted mortality (p = 0.01). Temperature maximums and overall temperature exposure were greater at the Inner Bay site and may explain why mortality affected these oysters sooner than oysters planted at the Outer Bay site. Differences in cumulative mortality were significant among stocks (p < 0.0001), but not between sites (p > 0.05). OsHV prevalence was similar among stocks (p > 0.05) and between sites (p > 0.05). No evidence of herpesvirus-induced Cowdry type A nuclear inclusions or other pathogens were observed. Changes in tissue and cellular architecture including dilation of the digestive tubules and nuclear chromatin margination and pycnosis were observed in OsHV-infected oysters, consistent with previously observed OsHV infections. Stocks with smaller oysters had higher mortality rates than those with larger oysters; growth rate did not correlate with mortalities (p > 0.05). Taken together, these data suggest that the OsHV may cause or act in synergy with temperature to kill Pacific oyster seed in Tomales Bay, but further investigation of OsHV etiology in seed oysters is needed.

  5. Estimation of regional hydrogeological properties for use in a hydrologic model of the Chesapeake Bay watershed

    NASA Astrophysics Data System (ADS)

    Seck, A.; Welty, C.

    2012-12-01

    Characterization of subsurface hydrogeologic properties in three dimensions and at large scales for use in groundwater flow models can remain a challenge owing to the lack of regional data sets and scatter in coverage, type, and format of existing small-scale data sets. This is the case for the Chesapeake Bay watershed, where numerous studies have been carried out to quantify groundwater processes at small scales but limited information is available on subsurface characteristics and groundwater fluxes at regional scales. One goal of this work is to synthesize disparate information on subsurface properties for the Chesapeake Bay watershed for use in a 3D integrated ParFlow model over an area of 400,000 km2 with a horizontal resolution of 1 km and a vertical resolution of 5 m. We combined different types of data at various scales to characterize hydrostratigraphy and hydrogeological properties. The conceptual hydrogeologic model of the study area is composed of two major regions. One region extends from the Valley and Ridge physiographic province south of New York to the Piedmont physiographic province in Maryland and Virginia. This region is generally characterized by fractured rock overlain by a mantle of regolith. Soil thickness and hydraulic conductivity values were obtained from the U.S. General Soil Map (STATSGO2). Saprolite thickness was evaluated using casing depth information from well completion reports from four state agencies. Geostatistical methods were used to generalize point data to the model extent and resolution. A three-dimensional hydraulic conductivity field for fractured bedrock was estimated using a published national map of permeability and depth- varying functions from literature. The Coastal Plain of Maryland, Virginia, Delaware and New Jersey constitutes the second region and is characterized by layered sediments. In this region, the geometry of 20 aquifers and confining units was constructed using interpolation of published contour maps of

  6. DINOFLAGELLATE CYST RECORDS AND HUMAN DISTURBANCE IN TWO NEIGHBORING ESTUARIES, NEW BEDFORD HARBOR AND APPONAGANSETT BAY, MASSACHUSETTS, USA

    EPA Science Inventory

    The dinoflagellate cyst records in sediments from New Bedford Harbor and Apponagansett Bay demonstrate sensitivity to environmental change caused by human activity in the watersheds over the last 500 years. Changes in the species richness, as well as absolute and relative abundan...

  7. Intra- and inter-annual trends in phosphorus loads and comparison with nitrogen loads to Rehoboth Bay, Delaware (USA)

    NASA Astrophysics Data System (ADS)

    Volk, Jennifer A.; Scudlark, Joseph R.; Savidge, Karen B.; Andres, A. Scott; Stenger, Robert J.; Ullman, William J.

    2012-01-01

    Monthly phosphorus loads from uplands, atmospheric deposition, and wastewater to Rehoboth Bay (Delaware) were determined from October 1998 to April 2002 to evaluate the relative importance of these three sources of P to the Bay. Loads from a representative subwatershed were determined and used in an areal extrapolation to estimate the upland load from the entire watershed. Soluble reactive phosphorus (SRP) and dissolved organic P (DOP) are the predominant forms of P in baseflow and P loads from the watershed are highest during the summer months. Particulate phosphorus (PP) becomes more significant in stormflow and during periods with more frequent or larger storms. Atmospheric deposition of P is only a minor source of P to Rehoboth Bay. During the period of 1998-2002, wastewater was the dominant external source of P to Rehoboth Bay, often exceeding all other P sources combined. Since 2002, however, due to technical improvements to the sole wastewater plant discharging directly to the Bay, the wastewater contribution of P has been significantly reduced and upland waters are now the principal source of P on an annualized basis. Based on comparison of N and P loads, primary productivity and biomass carrying capacity in Rehoboth Bay should be limited by P availability. However, due to the contrasting spatial and temporal patterns of N and P loading and perhaps internal cycling within the ecosystem, spatial and temporal variations in N and P-limitation within Rehoboth Bay are likely.

  8. Intra- and inter-annual trends in phosphorus loads and comparison with nitrogen loads to Rehoboth Bay, Delaware (USA)

    USGS Publications Warehouse

    Volk, J.A.; Scudlark, J.R.; Savidge, K.B.; Andres, A.S.; Stenger, R.J.; Ullman, W.J.

    2012-01-01

    Monthly phosphorus loads from uplands, atmospheric deposition, and wastewater to Rehoboth Bay (Delaware) were determined from October 1998 to April 2002 to evaluate the relative importance of these three sources of P to the Bay. Loads from a representative subwatershed were determined and used in an areal extrapolation to estimate the upland load from the entire watershed. Soluble reactive phosphorus (SRP) and dissolved organic P (DOP) are the predominant forms of P in baseflow and P loads from the watershed are highest during the summer months. Particulate phosphorus (PP) becomes more significant in stormflow and during periods with more frequent or larger storms. Atmospheric deposition of P is only a minor source of P to Rehoboth Bay. During the period of 1998-2002, wastewater was the dominant external source of P to Rehoboth Bay, often exceeding all other P sources combined. Since 2002, however, due to technical improvements to the sole wastewater plant discharging directly to the Bay, the wastewater contribution of P has been significantly reduced and upland waters are now the principal source of P on an annualized basis. Based on comparison of N and P loads, primary productivity and biomass carrying capacity in Rehoboth Bay should be limited by P availability. However, due to the contrasting spatial and temporal patterns of N and P loading and perhaps internal cycling within the ecosystem, spatial and temporal variations in N and P-limitation within Rehoboth Bay are likely. ?? 2011 Elsevier Ltd.

  9. Persistent organochlorine pollutants in eggs of colonial waterbirds from Galveston Bay and East Texas, USA

    USGS Publications Warehouse

    Frank, D.S.; Mora, M.A.; Sericano, J.L.; Blankenship, Alan L.; Kannan, K.; Giesy, J.P.

    2001-01-01

    Eggs of neotropic cormorants (Phalacrocorax brasilianus), black-crowned night herons (Nycticorax nycticorax), and great egrets (Ardea alba) nesting on several locations in Galveston Bay (TX, USA) and at two control sites outside the bay were collected during April-May 1996 and analyzed for chlorinated pesticides, PCBs, polychlorinated dibenzo-p-dioxins, and polychlorinated dibenzofurans. Additionally, concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TCDD-EQs) were determined by use of relative potency factors (TEQs) or the H4IIE-luc bioassay TCDD-EQs. Concentrations of 1,1,-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) were greater in eggs of neotropic cormorants from Alexander Island (mean = 1,040 ng/g wet wt) in the Houston Ship Channel (Houston, TX, USA) and in those from Telfair Island (mean = 1,460 ng/g wet wt), a reference location outside the bay, than in most locations inside the bay (mean range = 119-453 ng/g wet wt). Mean PCB concentrations were greater in eggs of neotropic cormorants from Alexander Island (mean = 5,720 ng/g wet wt) than in eggs of cormorants from areas farther away from the ship channel, including two reference sites outside the bay (mean range = 404-3,140 ng/g wet wt). The TCDD was the main dioxin congener detected in eggs from all locations within Galveston Bay. Instrumental TEQs in eggs ranged from 67 pg/g wet weight at control sites to 452 pg/g wet weight at Alexander Island. Concentrations of TCDD-EQs determined in the H4IIE assay were correlated with instrumental TEQs and were greater in eggs of cormorants from islands within the bay, although these were farther away from the ship channel. Overall, concentrations of DDE, PCBs, TCDD, and TCDD-EQs were less than the threshold levels known to affect reproduction. However, some eggs contained concentrations of total PCBs or DDE greater than what would elicit adverse effects on birds. No identifiable deformities or abnormalities were detected in embryos collected from

  10. Persistent organochlorine pollutants in eggs of colonial waterbirds from Galveston Bay and East Texas, USA.

    PubMed

    Frank, D S; Mora, M A; Sericano, J L; Blankenship, A L; Kannan, K; Giesy, J P

    2001-03-01

    Eggs of neotropic cormorants (Phalacrocorax brasilianus), black-crowned night herons (Nycticorax nycticorax), and great egrets (Ardea alba) nesting on several locations in Galveston Bay (TX, USA) and at two control sites outside the bay were collected during April-May 1996 and analyzed for chlorinated pesticides, PCBs, polychlorinated dibenzo-p-dioxins, and polychlorinated dibenzofurans. Additionally, concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TCDD-EQs) were determined by use of relative potency factors (TEQs) or the H4IIE-luc bioassay TCDD-EQs. Concentrations of 1,1,-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) were greater in eggs of neotropic cormorants from Alexander Island (mean = 1,040 ng/g wet wt) in the Houston Ship Channel (Houston, TX, USA) and in those from Telfair Island (mean = 1,460 ng/g wet wt), a reference location outside the bay, than in most locations inside the bay (mean range = 119-453 ng/g wet wt). Mean PCB concentrations were greater in eggs of neotropic cormorants from Alexander Island (mean = 5,720 ng/g wet wt) than in eggs of cormorants from areas farther away from the ship channel, including two reference sites outside the bay (mean range = 404-3,140 ng/g wet wt). The TCDD was the main dioxin congener detected in eggs from all locations within Galveston Bay. Instrumental TEQs in eggs ranged from 67 pg/g wet weight at control sites to 452 pg/g wet weight at Alexander Island. Concentrations of TCDD-EQs determined in the H4IIE assay were correlated with instrumental TEQs and were greater in eggs of cormorants from islands within the bay, although these were farther away from the ship channel. Overall, concentrations of DDE, PCBs, TCDD, and TCDD-EQs were less than the threshold levels known to affect reproduction. However, some eggs contained concentrations of total PCBs or DDE greater than what would elicit adverse effects on birds. No identifiable deformities or abnormalities were detected in embryos collected from

  11. Polyphosphate Accumulation in Benthic Biofilms in an Agricultural Watershed (Pennsylvania, USA)

    NASA Astrophysics Data System (ADS)

    Taylor, S.

    2015-12-01

    Nutrient loading has contributed to eutrophication in rivers and downstream systems throughout the mid-Atlantic region, USA. It is known that biofilms can be assessed to determine the amount of phosphorus (P) pollution in a system and the agricultural impacts it has on stream health. Polyphosphates are a storage system in algal cells and can be used to reflect the degree of nutrient loading to stream ecosystems. An ISES (in situ enrichment system) experiment was deployed in four flumes of a USDA maintained stream watershed for a 12-day period. In July-August of 2014, experimental vials of agar were enriched with six levels of P loading from 0.0 to 1,540.8 μg PO4-3/day under consistently N enriched conditions. At the end of this period natural growing biofilms were scraped off tiles established in each site and analyzed for chlorophyll, total P, and polyphosphate. While there were no significant differences found in biomass growth between each treatment (two-way ANOVA; F= 3.387, p>0.042), there were significant increases in P storage with increased P provided (F= 148.853, p<0.001). We measured consistent uptake patterns throughout the watershed, suggesting that uptake was a consistent feature of biofilms throughout the landscape (F= 4.172, p>0.05). A large percentage of total P was also stored as polyphosphate in the treatments with added P in relation to the ambient tiles collected. Given these findings, we propose that polyphosphate storage in stream biofilms are an important, early warning indicator for changing trophic status in streams compared with biomass metrics (e.g., chlorophyll); therefore, P storage in stream algae reflects loading from throughout the terrestrial landscape.

  12. Temporal and spatial patterns of phytoplankton production in Tomales Bay, California, U.S.A.

    USGS Publications Warehouse

    Cole, B.E.

    1989-01-01

    Primary productivity in the water column was measured 14 times between April 1985 and April 1986 at three sites in Tomales Bay, California, USA The conditions at these three stations encompassed the range of hydrographic conditions, phytoplankton biomass, phytoplankton community composition, and turbidity typical of this coastal embayment. Linear regression of the measured daily carbon uptake against the composite parameter B Zp Io (where B is the average phytoplankton biomass in the photic zone; Zp is the photic depth; and Io is the daily surface insolation) indicates that 90% of the variability in primary productivity is explained by variations in phytoplankton biomass and light availability. The linear function derived using Tomales Bay data is essentially the same as that which explains more than 80% of the variation in productivity in four other estuarine systems. Using the linear function and measured values for B, Zp, and Io, the daily photic-zone productivity was estimated for 10 sites at monthly intervals over the annual period. The average daily photic-zone productivity for the 10 sites ranged from 0??2 to 2??2 g C m-2. The bay-wide average annual primary productivity in the water column was 400 g C m-2, with most of the uptake occuring in spring and early summer. Spatial and temporal variations in primary productivity were similar to variations in phytoplankton biomass. Productivity was highest in the seaward and central regions of the bay and lowest in the shallow landward region. ?? 1989.

  13. Improving lakebed sediment quality in an urban estuary, Presque Isle Bay, Lake Erie, USA

    NASA Astrophysics Data System (ADS)

    Foyle, A. M.; Norton, K. P.

    2007-12-01

    Presque Isle Bay, Lake Erie, is a microtidal freshwater estuary on the North American Great Lakes. It is one of 40 remaining environmental Areas of Concern (AoCs) on the Great Lakes that have one or more water, habitat, or sediment quality impairments as defined by the International Joint Commission. In-situ natural capping using sediment from to-be-remediated watersheds and other sources is being considered as the most feasible means of remediating contaminated sediments in the estuary. A multi-decade sediment budget shows that, when localized anthropogenic effects are accounted for, the estuary net-accumulated sediment over time from three major sources: the Lake Erie littoral system (20%), streams (25%), and bank erosion and bluff recession (41%). The non-stream sources supply environmentally clean sediment from ancient coastal deposits along the shoreline, and from the modern littoral system. However, organic and metallic contaminants are supplied by streams and run-off and remain a remediation challenge. From a geological perspective, natural capping of contaminated sediment over the next several decades is a viable solution for the majority of the bay. The mechanism may not work effectively in all areas because approximately 25% of the bay floor is moderately net- erosional or accumulates sediments very slowly.

  14. Stream Community Structure: An Analysis of Riparian Forest Buffer Restoration in the Chesapeake Bay Watershed

    NASA Astrophysics Data System (ADS)

    Orzetti, L. L.; Jones, R. C.

    2005-05-01

    Forested riparian buffer zones have been proposed as an important aid in curtailing upland sources of pollution before they reach stream surface waters, and enhancing habitat for stream organisms. Our objective was to test the efficacy of restored forest riparian buffers along streams in the Chesapeake Bay watershed by examining the stream macrobenthic community structure. To test our hypothesis, we collected riffle benthic and water samples, and performed habitat evaluations at 30 stream sites in the mid-Atlantic Piedmont, ranging in buffer age from 0 to greater than 50 years of age. Results showed that habitat, water quality, and benthic macroinvertebrate metrics improved with age of restored buffer. Habitat scores were driven mostly by instream substrate availability and width and age of riparian buffer zones. Water quality parameters varied within buffer age groups depending age of surrounding forest vegetation. Benthic invertebrate taxa richness, % EPT, % Plecoptera, % Ephemeroptera, and the FBI all improved with age of buffer zone. Instream habitat quality was the greatest driver of benthic macroinvertebrate community diversity and health, and appeared to plateau within 10-15 years of restoration with noticeable improvements occurring within 5-10 years post restoration.

  15. Effects of contaminants on Double-crested Cormorant reproduction in Green Bay, Wisconsin, USA

    USGS Publications Warehouse

    Custer, T.W.; Custer, Christine M.; Stromborg, K.L.; Melancon, M.J.; Adams, N.J.; Slotow, R.H.

    1998-01-01

    In 1994 and 1995, Double-crested Cormorants Phalacrocorax auritus were monitored from egg-laying through 12 days of age at Cat Island, Green Bay, Wisconsin, USA. Sample eggs at hatching were analysed for organochlorines (including total PCBs, PCB congeners, and DDE), hepatic microsomal ethoxyresorufin-O-dealkylase (EROD) activity in livers of embryos, and eggshell thickness. The number of eggs per nest that hatched and survived to i 2 days of age was estimated to be 2.2 in 1994 and 2.0 in 1995. Hatching success of eggs was not correlated with PCBs, the toxicity of PCBs based on congeners, or EROD activity. Hatching success was correlated with eggshell thickness and negatively correlated with DDE concentrations. Even though the insecticide DDT was banned in the early 1970s, we suggest that DDE concentrations in cormorant eggs in Green Bay are still having an affect on reproduction in this species.

  16. Effects of contaminants on Double-crested Cormorant reproduction in Green Bay, Wisconsin, USA

    USGS Publications Warehouse

    Custer, T.W.; Custer, Christine M.; Stromborg, K.L.; Melancon, M.J.; Adams, N.J.; Slotow, R.H.

    1999-01-01

    In 1994 and 1995, Double-crested Cormorants Phalacrocorax auritus were monitored from egg-laying through 12 days of age at Cat Island, Green Bay, Wisconsin, USA. Sample eggs at hatching were analysed for organochlorines (including total PCBs, PCB congeners, and DDE), hepatic microsomal ethoxyresorufin-O-dealkylase (EROD) activity in livers of embryos, and eggshell thickness. The number of eggs per nest that hatched and survived to i 2 days of age was estimated to be 2.2 in 1994 and 2.0 in 1995. Hatching success of eggs was not correlated with PCBs, the toxicity of PCBs based on congeners, or EROD activity. Hatching success was correlated with eggshell thickness and negatively correlated with DDE concentrations. Even though the insecticide DDT was banned in the early 1970s, we suggest that DDE concentrations in cormorant eggs in Green Bay are still having an affect on reproduction in this species.

  17. Sedimentary Evidence for Land Use Change in the Narragansett Bay Watershed: Late Woodland period (~500 AD) to the present

    NASA Astrophysics Data System (ADS)

    Salacup, J. M.; Altabet, M. A.; Herbert, T.; Prell, W. L.

    2012-12-01

    In the U.S., the last ~300 years have been a period of progressive and widespread resource exploitation, ecosystem degradation, and habitat destruction. In southern New England, the European Colonists thrived on the spread of slave-based plantation farming, which peaked ~1750 in RI. They produced commodities such as livestock, apples, onions, flax, and dairy. Trees felled to produce the necessary pasture- and farm-land were quickly used as lumber for boards, planks, timber, and barrels. In 1793, Slater Mill, located on the Blackstone River at the head of Narragansett Bay, was the first mill in the U.S to spin yarn using water power, making it the birthplace of the U.S Industrial Revolution. The ensuing urbanization drove the human population of the watershed up from ~50,000 in 1790 to more than 2 million by the year 2000. More recently, the Bay has experienced episodic hypoxic events [1]. These events correlate well with spatial and temporal patterns of nutrients and productivity [2] suggesting that human-induced increases in nutrient nitrogen and phosphorus are responsible for eutrophication-induced oxygen depletion [3]. However, these post-Colonial land use changes have yet to be characterized within the longer context of Native American land use practices, mainly due to the lack of historical records for the period. Additionally, the impact of this ecosystem disturbance on the Bay has not been fully described. Here we present results based on sedimentary profiles of biomarkers diagnostic for soil delivery to marine systems, branched glycerol dialykl glycerol tetraethers, and pollen for disturbance taxa, that suggest land use change began in the Bay's watershed 300 years before European contact. This contradicts long standing ideas regarding the land use practices of local tribes but agrees with new archaeological findings suggesting large semi-permanent settlements and widespread horticulture of maize may have been the norm at this time. We also show results of

  18. Drivers of phytoplankton dynamics in old Tampa Bay, FL (USA), a subestuary lagging in ecosystem recovery

    NASA Astrophysics Data System (ADS)

    Corcoran, Alina A.; Wolny, Jennifer; Leone, Erin; Ivey, James; Murasko, Susan

    2017-02-01

    In the past four decades, consistent and coordinated management actions led to the recovery of Tampa Bay, FL (USA) - an estuary that was declared dead in the 1970s. An exception to this success story is Old Tampa Bay, the northernmost subestuary of the system. Compared to the other bay segments, Old Tampa Bay is characterized by poorer water quality and spring and summer blooms of cyanobacteria, picoplankton, diatoms, and the saxitoxin-producing dinoflagellate Pyrodinium bahamense. Together, these blooms contribute to light attenuation and lagging recovery of seagrass beds. Yet, studies of phytoplankton dynamics within Old Tampa Bay have been limited - both in number and in their spatiotemporal resolution. In this study, we used field sampling and continuous monitoring to (1) characterize temporal and spatial variability in phytoplankton biomass and community composition and (2) identify key drivers of the different phytoplankton blooms in Old Tampa Bay. Overall, temporal variability in phytoplankton biomass (using chlorophyll a as a proxy) and community composition surpassed spatial variability of these parameters. We found a base community of small diatoms and flagellates, as well as certain dinoflagellates, that persisted year round in the system. Seasonally, freshwater runoff stimulated phytoplankton growth, specifically that of chlorophytes, cyanobacteria and other dinoflagellates - consistent with predictions based on ecological theory. On shorter time scales, salinity, visibility, and freshwater inflows were important predictors of phytoplankton biomass. With respect to P. bahamense, environmental drivers including salinity, temperature and dissolved nutrient concentrations explained ∼24% of the variability in cell abundance, indicating missing explanatory parameters in our study for this taxon, such as cyst density and location of cyst beds. Spatially, we found differences in community trajectories across north-south and west-east gradients, with the

  19. Selenium bioaccumulation and body condition in shorebirds and terns breeding in San Francisco Bay, California, USA

    USGS Publications Warehouse

    Ackerman, Joshua T.; Eagles-Smith, Collin A.

    2009-01-01

    The present study evaluated Se bioaccumulation in four waterbird species (n = 206 birds) that breed within San Francisco Bay, California, USA: American avocets (Recurvirostra americana), black-necked stilts (Himantopus mexicanus), Forster's terns (Sterna forsteri), and Caspian terns (Hydroprogne caspia). Selenium concentrations were variable and influenced by several factors, including species, region, reproductive stage, age, and sex. Adult Se concentrations (μg/g dry wt) in livers ranged from 3.07 to 48.70 in avocets (geometric mean ± standard error, 7.92 ± 0.64), 2.28 to 41.10 in stilts (5.29 ± 0.38), 3.73 to 14.50 in Forster's terns (7.13 ± 0.38), and 4.77 to 14.40 in Caspian terns (6.73 ± 0.78). Avocets had higher Se concentrations in the North Bay compared to the South Bay, whereas stilt Se concentrations were similar between these regions and Forster's terns had lower Se concentrations in the North Bay compared to the South Bay. Female avocets had higher Se concentrations than male avocets, but this was not the case for stilts and Forster's terns. Of the factors assessed, reproductive stage had the most consistent effect among species. Prebreeding birds tended to have higher liver Se concentrations than breeding birds, but this trend was statistically significant only for Forster's terns. Forster's tern chicks had lower Se concentrations than Forster's tern adults, whereas avocet and stilt adults and chicks were similar. Additionally, body condition was negatively related to liver Se concentrations in Forster's tern adults but not in avocet, stilt, or Caspian tern adults and chicks. These variable results illustrate the complexity of Se bioaccumulation and highlight the need to sample multiple species and examine several factors to assess the impact of Se on wildlife.

  20. Synthesis of nutrient and sediment data for watersheds within the Chesapaeake Bay drainage basin

    USGS Publications Warehouse

    Langland, M.J.; Lietman, P.L.; Hoffman, S.A.

    1995-01-01

    Nutrient and sediment data collected by Federal and state agencies from 1972 through 1992 at 1,058 surface-water sites in nontidal parts of the Chesapeake Bay Basin were compiled into a large database. Adequate nutrient, sediment, and streamflow data were not available to compute annual loads for all sites because water-quality monitoring at many of the sites was either short term or noncontinuous or because stream-flow was not measured. Annual nutrient and sediment loads were calculated at a total of 127 sites. Annual loads of dissolved nitrate were calculated for 108 sites, but total nitrogen loads could be calculated for only 48 of these sites because ammonia plus organic nitrogen data were not available for many of these 108 sites. Annual loads of total phosphorus were calculated for 99 sites, and annual loads of suspended sediment were calculated for 33 sites. Loads could be calculated for only a very few sites in the Juniata River Basin (a tributary to the Susquehanna River), the York River Basin, the middle and lower reaches of the James River, and the nontidal parts of the eastern shore of the Bay. Geographic Information System (GIS) spatial data sets of land use, physiographic province, rock type, and watershed delineation were compiled for the entire Chesapeake Bay Basin (approximately 64,000 square miles). The nutrient- and sediment-yield were evaluated with respect to land use, physiographic province, rock type, and hydrologic characteristics. During years that the mean streamflow was about equal to the long-term mean streamflow, the Susquehanna River contributed about 50 percent of the freshwater, 66 percent of the total nitrogen, and 40 percent of the total phosphorus transported by tributaries to the Bay. Nutrient and sediment data were available for less than 18 percent of the predominantly agricultural areas underlain by siliciclastic rock and for less than 35 percent of the predominantly agricultural areas underlain by either carbonate rock or

  1. Hydrological and biogeochemical investigation of an agricultural watershed, southeast New Hampshire, USA

    NASA Astrophysics Data System (ADS)

    Davis, J. M.; McDowell, W. H.; Campbell, J. E.; Hristov, A. N.

    2010-12-01

    Developing sustainable agricultural practices and policies requires an understanding of the hydrological and biological processes that control nutrient fluxes and how those processes are manifested in nutrient loading of surface water bodies. Groundwater and surface water from the UNH Organic Research Dairy, located in southeast New Hampshire, flow into the Lamprey River and then into the Great Bay, New Hampshire; both are experiencing increasing nutrient loads. The farm hosts approximately 80 Jersey cows (40 milking) and is located on relatively thin (<10m) glacial deposits that include sandy glacial till moraines, an ice-contact delta, and marine silt and clay overlying fractured calcareous quartzite. Recharge of precipitation is the dominant mode through which nutrients are introduced into the hydrologic system. Intensive meteorological, hydrological, and biogeochemical monitoring of a 35 hectare watershed that includes the main farm operation buildings and several pastures has been underway since June 2009. A three-dimensional transient unsaturated-saturated groundwater flow model was developed using LIDAR topography and detailed field mapping. The transient model was calibrated to observed water level and streamflow observations. Model results suggest that summer recharge rates vary considerably across the site and depth to the water table is the dominant control on the recharge flux. Areas having depth to water of 1-2 m experience the greatest recharge (up to 60% of precipitation). Areas with deeper water tables experience greater evapotranspiration from the vadose zone, and shallower water tables experience greater runoff. Water budget calculations suggest that the hydrologic fluxes occur predominately in the shallow groundwater, wetlands, and small surface streams draining the watershed. High dissolved nitrogen (N) concentrations (up to an average concentration of 35 mg N/L) are observed in groundwater immediately downgradient from the main farm operation

  2. A Regionalized Flow Duration Curve Method to Predict Streamflow for Ungauaged Basins: A Case Study of the Rappahannock Watershed in Virginia, USA

    EPA Science Inventory

    A method to predict streamflow for ungauged basins of the Mid-Atlantic Region, USA was applied to the Rappahannock watershed in Virginia, USA. The method separates streamflow time series into magnitude and time sequence components. It uses the regionalized flow duration curve (RF...

  3. Mercury concentrations and loads in a large river system tributary to San Francisco Bay, California, USA

    USGS Publications Warehouse

    David, N.; McKee, L.J.; Black, F.J.; Flegal, A.R.; Conaway, C.H.; Schoellhamer, D.H.; Ganju, N.K.

    2009-01-01

    In order to estimate total mercury (HgT) loads entering San Francisco Bay, USA, via the Sacramento-San Joaquin River system, unfiltered water samples were collected between January 2002 and January 2006 during high flow events and analyzed for HgT. Unfiltered HgT concentrations ranged from 3.2 to 75 ng/L and showed a strong correlation (r2 = 0.8, p < 0.001, n = 78) to suspended sediment concentrations (SSC). During infrequent large floods, HgT concentrations relative to SSC were approximately twice as high as observed during smaller floods. This difference indicates the transport of more Hg-contaminated particles during high discharge events. Daily HgT loads in the Sacramento-San Joaquin River at Mallard Island ranged from below the limit of detection to 35 kg. Annual HgT loads varied from 61 ?? 22 kg (n = 5) in water year (WY) 2002 to 470 ?? 170 kg (n = 25) in WY 2006. The data collected will assist in understanding the long-term recovery of San Francisco Bay from Hg contamination and in implementing the Hg total maximum daily load, the long-term cleanup plan for Hg in the Bay. ?? 2009 SETAC.

  4. Mercury and organic carbon dynamics during runoff episodes from a northeastern USA watershed

    USGS Publications Warehouse

    Schuster, P.F.; Shanley, J.B.; Marvin-DiPasquale, M.; Reddy, M.M.; Aiken, G.R.; Roth, D.A.; Taylor, H.E.; Krabbenhoft, D.P.; DeWild, J.F.

    2008-01-01

    Mercury and organic carbon concentrations vary dynamically in streamwater at the Sleepers River Research Watershed in Vermont, USA. Total mercury (THg) concentrations ranged from 0.53 to 93.8 ng/L during a 3-year period of study. The highest mercury (Hg) concentrations occurred slightly before peak flows and were associated with the highest organic carbon (OC) concentrations. Dissolved Hg (DHg) was the dominant form in the upland catchments; particulate Hg (PHg) dominated in the lowland catchments. The concentration of hydrophobic acid (HPOA), the major component of dissolved organic carbon (DOC), explained 41-98% of the variability of DHg concentration while DOC flux explained 68-85% of the variability in DHg flux, indicating both quality and quantity of the DOC substantially influenced the transport and fate of DHg. Particulate organic carbon (POC) concentrations explained 50% of the PHg variability, indicating that POC is an important transport mechanism for PHg. Despite available sources of DHg and wetlands in the upland catchments, dissolved methylmercury (DmeHg) concentrations in streamwaters were below detection limit (0.04 ng/L). PHg and particulate methylmercury (PmeHg) had a strong positive correlation (r 2 = 0.84, p < 0.0001), suggesting a common source; likely in-stream or near-stream POC eroded or re-suspended during spring snowmelt and summer storms. Ratios of PmeHg to THg were low and fairly constant despite an apparent higher methylmercury (meHg) production potential in the summer. Methylmercury production in soils and stream sediments was below detection during snowmelt in April and highest in stream sediments (compared to forest and wetland soils) sampled in July. Using the watershed approach, the correlation of the percent of wetland cover to TmeHg concentrations in streamwater indicates that poorly drained wetland soils are a source of meHg and the relatively high concentrations found in stream surface sediments in July indicate these zones are

  5. Distribution characteristics of volatile methylsiloxanes in Tokyo Bay watershed in Japan: Analysis of surface waters by purge and trap method.

    PubMed

    Horii, Yuichi; Minomo, Kotaro; Ohtsuka, Nobutoshi; Motegi, Mamoru; Nojiri, Kiyoshi; Kannan, Kurunthachalam

    2017-05-15

    Surface waters including river water and effluent from sewage treatment plants (STPs) were collected from Tokyo Bay watershed, Japan, and analyzed for seven cyclic and linear volatile methylsiloxanes (VMSs), i.e., D3, D4, D5, D6, L3, L4, and L5 by an optimized purge and trap extraction method. The total concentrations of seven VMSs (ΣVMS) in river water ranged from <4.9 to 1700ng/L (mean: 220ng/L). The individual mean concentrations of cyclic VMSs in surface waters were; 10ng/L for D3, 13ng/L for D4, 180ng/L for D5, and 18ng/L for D6. The concentrations of ΣVMS determined in STP effluents varied widely from 99 to 2500ng/L and the individual mean concentrations were 21ng/L for D3, 27ng/L for D4, 540ng/L for D5, and 45ng/L for D6. D5, which is widely used in personal-care products, was found to be the most abundant compound in both river water and STP effluent. Linear VMSs were detected at much lower frequency and concentrations than those of cyclic VMSs. The measured concentrations of D4 were below the no-observed effect concentration (NOEC). The annual emission of ΣVMS through STPs into Tokyo Bay watershed was estimated at 2300kg. Our results indicate widespread distribution of VMSs in Tokyo Bay watershed and the influence of domestic wastewater discharges as a source of VMSs in the aquatic environment.

  6. Tumors in brown bullheads in the Chesapeake Bay watershed: analysis of survey data from 1992 through 2006.

    PubMed

    Pikney, Alfred E; Harshbarger, John C; Rutter, Michael A

    2009-06-01

    Liver and skin tumor prevalences in brown bullheads Ameiurus nebulosus have been used in the North American Great Lakes to designate highly contaminated areas of concern and monitor their recovery. Here we interpret the results of six surveys conducted in the Chesapeake Bay watershed between 1992 and 2006, with data for 647 fish. The objective has been to develop an adequate database to critically evaluate the use of tumor prevalence as a habitat quality indicator within the watershed. Surveys featured randomized fish collection; recording of sex, length, weight, and age; and histopathology of all livers and all raised skin lesions. The Bayes information criterion was used to analyze all possible combinations of age, gender, length, and weight as covariates for logistic regression. Length and gender were the covariates that best described liver tumor prevalence. There were no covariates in the model for skin tumor prevalence. In some surveys, biomarkers, such as biliary polynuclear aromatic hydrocarbon (PAH)-like metabolites, hepatic cytochrome P450 activity, and hepatic DNA adducts, were used with sediment and tissue chemistry data to evaluate classes of chemicals as likely contributors to tumor prevalence. We highlight two surveys of the Anacostia River, Washington, D.C. (average = 55% liver tumors, 23% skin tumors), where sediment PAHs, biliary PAH-like metabolites, and hepatic DNA adducts were high, suggesting that PAHs play a major role. We show that logistic regression is an appropriate procedure for comparing "contaminated" versus "reference" locations, and we evaluate the utility of tumor surveys as an environmental indicator for the Chesapeake Bay watershed.

  7. Suspended sediment transport at the instantaneous and event time scales in semiarid watersheds of southeastern Arizona, USA

    NASA Astrophysics Data System (ADS)

    Gao, Peng; Nearing, Mark A.; Commons, Michael

    2013-10-01

    We investigated the high variability of suspended sediment transport in 16 watersheds of Walnut Gulch, southeastern Arizona, USA that were distinguished at three spatial scales: the plot (ca. 0.001-0.01 km2), unit-source (ca. 0.01-0.1 km2), and large (ca. 1-150 km2) scales. Event-based data of water discharge and suspended sediment concentration were compiled in variable periods between the 1960s and 2010s. By subjectively distinguishing five different intraevent transport patterns that may be ascribed to a combination of various hydrological and sediment-transport processes, we showed that no single sediment rating curve could be developed for these data. However, at the event temporal scale, event specific sediment yield (SSYe, t/km2) was significantly correlated to event runoff depth (h, mm) for all transport patterns of the watersheds, suggesting that the complexity of suspended sediment transport at the intraevent scale is effectively reduced at the event scale regardless of watershed sizes. Further regression analysis indicated that the SSYe-h relationship can be generally characterized by a proportional model, SSYe = nh where n, is conceptually equivalent to the volume-weighted event mean sediment concentration and is mainly determined by large events. For watersheds dominated by shrub cover, the change of the n value with watershed area was limited and thus may be reasonably regarded as a constant, implying that despite the highly variable suspended sediment concentrations during individual storm events in variable-sized watersheds, the synoptic effect of suspended sediment transport was similar and may be determined by a single value.

  8. Exploiting the Free Landsat Archive for Operational Monitoring of Ecosystem Condition and Change Across the Chesapeake Bay Watershed

    NASA Technical Reports Server (NTRS)

    BrowndeColstoun, Eric

    2010-01-01

    For the first time, all imagery acquired by the Landsat series of satellites is being made available by the USGS to users at no cost. This represents a key opportunity to use Landsat in a truly operational monitoring framework: large regions of the U.S. such as the Chesapeake Bay Watershed can now be analyzed using "wall-to-wall" imagery at timescales from approximately 1 month to several years. With the future launch of the Landsat Data Continuity Mission (LDCM) and Decadal Survey missions such as the hyperspectral HyspIRI, it is imperative to develop robust processing systems to perform annual ecosystem assessments over large regions such as the Chesapeake Bay. We have been working at NASA's Goddard Space Flight Center (GSFC) to develop an integrative framework for inserting 30m, annual, Landsat based data and derived products into the existing decision support system for the Bay, with a particular focus on ecosystem condition and changes over the entire watershed. The basic goal is to use a 'stack' of Landsat imagery with 40% or less cloud cover to produce multi-date (2005-2009 period), cloud/shadow/gap-free composited surface reflectance products that will support the creation of watershed scale land cover/ use products and the monitoring of ecosystem change across the Bay. Our scientific focus extends beyond the conventional definition of land cover (i.e. a classification of vegetation type) as we propose to monitor both changes in surface type (e.g. forest to urban), vegetation structure (e.g. forest disturbance due to logging or insect damage), as well as winter crop cover. These processes represent a continuum from large, interannual changes in land cover type, to subtler, intra-annual changes associated with short-term disturbance. The free Landsat data are being processed to surface reflectance and composited using the existing Landsat Ecosystem Disturbance Adaptive Processing System here at NASA/ GSFC, and land cover products (type, tree cover

  9. Soil Erosion and Sediment Losses from the Ridge Watersheds in the Guánica Bay, Puerto Rico

    NASA Astrophysics Data System (ADS)

    Yuan, Yongping; Taguas, Encarnación; Hu, Wenhui

    2014-05-01

    Puerto Rico faces considerable challenges regarding sustainable land use and effects of land use on adjacent coastal ecosystems and the services they provide. One primary concern is increased sediment loading to reservoirs and ultimately to Guánica Bay and reef areas outside the Bay. Studies by scientists in Puerto Rico have suggested that nutrient and sediment contaminants have increased 5 to 10 fold since pre-colonial levels and an additional 2 to 3 fold in the last 40-50 years (Sturm et al., 2012). Sediment deposition has significantly reduced the storage capacity of several reservoirs, and the associated contaminants and nutrients within the terrestrial soil particles of sediment can stress corals and negatively impact reef health. Sedimentation can also reduce photosynthetic activity of aquatic plants and algae, and increase water-treatment costs for domestic and industrial uses (Estades Hernández, 1997). Therefore, it is important to understand soil erosion and sediment transport processes. In this study, we analyze sediment losses from ridge watersheds of the Guánica Bay and try to understand the main factors causing soil erosion and sediment in those ridge watersheds. Our specific objectives were: 1) to quantify sediment contributions to Guánica Bay and identify sediment sources; 2) seek factors that impact the sediment loss and explore alternative strategies to reduce soil erosion and sediment loading to the reservoirs, Guánica Bay and the coastal zone. It was found that sediment loss in those ridge watersheds was mainly caused by interaction of heavy rainfall (especially the hurricanes) and steep mountainous slopes. Coffee planting increased the risk of soil erosion, which the loss of protective canopy for sun-grown coffee exacerbated. In addition, rainy seasons (February to May and August to November) contributed more than 80% of annual sediment loss. Exploration of different land use scenarios found that coffee land use yielded more sediment per

  10. Spatial and temporal relationships among watershed mining, water quality, and freshwater mussel status in an eastern USA river.

    PubMed

    Zipper, Carl E; Donovan, Patricia F; Jones, Jess W; Li, Jing; Price, Jennifer E; Stewart, Roger E

    2016-01-15

    The Powell River of southwestern Virginia and northeastern Tennessee, USA, drains a watershed with extensive coal surface mining, and it hosts exceptional biological richness, including at-risk species of freshwater mussels, downstream of mining-disturbed watershed areas. We investigated spatial and temporal patterns of watershed mining disturbance; their relationship to water quality change in the section of the river that connects mining areas to mussel habitat; and relationships of mining-related water constituents to measures of recent and past mussel status. Freshwater mussels in the Powell River have experienced significant declines over the past 3.5 decades. Over that same period, surface coal mining has influenced the watershed. Water-monitoring data collected by state and federal agencies demonstrate that dissolved solids and associated constituents that are commonly influenced by Appalachian mining (specific conductance, pH, hardness and sulfates) have experienced increasing temporal trends from the 1960s through ~2008; but, of those constituents, only dissolved solids concentrations are available widely within the Powell River since ~2008. Dissolved solids concentrations have stabilized in recent years. Dissolved solids, specific conductance, pH, and sulfates also exhibited spatial patterns that are consistent with dilution of mining influence with increasing distance from mined areas. Freshwater mussel status indicators are correlated negatively with dissolved solids concentrations, spatially and temporally, but the direct causal mechanisms responsible for mussel declines remain unknown.

  11. Response of aquatic macrophytes to human land use perturbations in the watersheds of Wisconsin lakes, U.S.A.

    USGS Publications Warehouse

    Sass, Laura L.; Bozek, Michael A.; Hauxwell, Jennifer A.; Wagner, Kelly; Knight, Susan

    2010-01-01

    Aquatic macrophyte communities were assessed in 53 lakes in Wisconsin, U.S.A. along environmental and land use development gradients to determine effects human land use perturbations have on aquatic macrophytes at the watershed and riparian development scales. Species richness and relative frequency were surveyed in lakes from two ecoregions: the Northern Lakes and Forests Ecoregion and the Southeastern Wisconsin Till Plain Ecoregion. Lakes were selected along a gradient of watershed development ranging from undeveloped (i.e., forested), to agricultural to urban development. Land uses occurring in the watershed and in perimeters of different width (0–100, 0–200, 0–500, and 0–1000 m from shore, in the watershed) were used to assess effects on macrophyte communities. Snorkel and SCUBA were used to survey aquatic macrophyte species in 18 quadrats of 0.25 m2 along 14 transects placed perpendicular to shore in each lake. Effects of watershed development (e.g., agriculture and/or urban) were tested at whole-lake (entire littoral zone) and near-shore (within 7 m of shore) scales using canonical correspondence analysis (CCA) and linear regression. Overall, species richness was negatively related to watershed development, while frequencies of individual species and groups differed in level of response to different land use perturbations. Effects of land use in the perimeters on macrophytes, with a few exceptions, did not provide higher correlations compared to land use at the watershed scale. In lakes with higher total watershed development levels, introduced species, particularly Myriophyllumspicatum, increased in abundance and native species, especially potamids, isoetids, and floating-leaved plants, declined in abundance. Correlations within the northern and southeastern ecoregions separately were not significant. Multivariate analyses suggested species composition is driven by environmental responses as well as human development pressures. Both water

  12. Climate Change and the Evolution and Fate of the Tangier Islands of Chesapeake Bay, USA

    NASA Astrophysics Data System (ADS)

    Schulte, David M.; Dridge, Karin M.; Hudgins, Mark H.

    2015-12-01

    Climate change and associated sea level rise (SLR) are already impacting low-lying coastal areas, including islands, throughout the world. Many of these areas are inhabited, many will need to be abandoned in coming decades as SLR continues. We examine the evolution (1850-2013) of the last inhabited offshore island in Virginia waters of Chesapeake Bay USA, the Tangier Islands. Three SLR scenarios, a low, mid, and high, were considered. Since 1850, 66.75% of the islands landmass has been lost. Under the mid-range SLR scenario, much of the remaining landmass is expected to be lost in the next 50 years and the Town will likely need to be abandoned. The high SLR scenario will accelerate the land loss and subsidence, such that the Town may need to be abandoned in as few as 25 years. We propose a conceptual plan that would significantly extend the lifespan of the islands and Town.

  13. Metals in horseshoe crab eggs from Delaware Bay, USA: temporal patterns from 1993 to 2012.

    PubMed

    Burger, Joanna; Tsipoura, Nellie

    2014-10-01

    The health of horseshoe crab (Limulus polyphemus) eggs is important not only to maintain horseshoe crab populations, but because they are a resource for higher trophic levels, such as fish and shorebirds. We examined the concentrations of arsenic, cadmium, chromium, lead, manganese, mercury, and selenium in the eggs of horseshoe crabs from Delaware Bay (between New Jersey and Delaware, USA) in 1993, 1994, 1995, 1999, 2000, and 2012 to determine if there were significant temporal changes and if levels appear to pose a health risk to the crabs themselves, or to predators that consume them. All metal levels declined in horseshoe crab eggs between 1994 and 2012, although the declines were much less consistent for lead and chromium than that for mercury and cadmium. Levels of contaminants found in these eggs are well below those known to cause adverse effects in the crabs themselves or to organisms that consume them, such as migrating shorebirds.

  14. Tidally generated sea-floor lineations in Bristol Bay, Alaska, USA

    NASA Astrophysics Data System (ADS)

    Marlow, M. S.; Stevenson, A. J.; Chezar, H.; McConnaughey, R. A.

    1999-12-01

    Highly reflective linear features occur in water depths of 20-30 m in northern Bristol Bay (Alaska, USA) and are, in places, over 600 m in length. Their length-to-width ratio is over 100:1. The lineations are usually characterized by large transverse ripples with wavelengths of 1-2 m. The lineations trend about N60°E, and are spaced between 20 and 350 m. Main tidal directions near the lineations are N60°E (flood) and S45°W (ebb), which are parallel to subparallel to the lineations. They suggest that the lineations may be tidally generated. The lineations may be bright sonar reflections from a winnowed lag concentrate of coarse sand.

  15. Tidally generated sea-floor lineations in Bristol Bay, Alaska, USA

    USGS Publications Warehouse

    Marlow, M. S.; Stevenson, A.J.; Chezar, H.; McConnaughey, R.A.

    1999-01-01

    Highly reflective linear features occur in water depths of 20-30 m in northern Bristol Bay (Alaska, USA) and are, in places, over 600 m in length. Their length-to-width ratio is over 100:1. The lineations are usually characterized by large transverse ripples with wavelengths of 1-2 m. The lineations trend about N60??E, and are spaced between 20 and 350 m. Main tidal directions near the lineations are N60??E (flood) and S45??W (ebb), which are parallel to subparallel to the lineations. They suggest that the lineations may be tidally generated. The lineations may be bright sonar reflections from a winnowed lag concentrate of coarse sand.

  16. Climate Change and the Evolution and Fate of the Tangier Islands of Chesapeake Bay, USA

    PubMed Central

    Schulte, David M.; Dridge, Karin M.; Hudgins, Mark H.

    2015-01-01

    Climate change and associated sea level rise (SLR) are already impacting low-lying coastal areas, including islands, throughout the world. Many of these areas are inhabited, many will need to be abandoned in coming decades as SLR continues. We examine the evolution (1850-2013) of the last inhabited offshore island in Virginia waters of Chesapeake Bay USA, the Tangier Islands. Three SLR scenarios, a low, mid, and high, were considered. Since 1850, 66.75% of the islands landmass has been lost. Under the mid-range SLR scenario, much of the remaining landmass is expected to be lost in the next 50 years and the Town will likely need to be abandoned. The high SLR scenario will accelerate the land loss and subsidence, such that the Town may need to be abandoned in as few as 25 years. We propose a conceptual plan that would significantly extend the lifespan of the islands and Town. PMID:26657975

  17. Linking watershed nitrogen sources with nitrogen dynamics in rivers of western Oregon, USA

    EPA Science Inventory

    We found a wide range of riverine N yields from the study basins, ranging from one to 70 kg N/ha/yr. Across the study basins, N export was more strongly correlated to fertilizer application rates than percent of agricultural area in the watershed. Low watershed N yields reflect...

  18. Spatial Predictive Modeling and Remote Sensing of Land Use Change in the Chesapeake Bay Watershed

    NASA Technical Reports Server (NTRS)

    Goetz, Scott J.; Bockstael, Nancy E.; Jantz, Claire A.

    2005-01-01

    This project was focused on modeling the processes by which increasing demand for developed land uses, brought about by changes in the regional economy and the socio-demographics of the region, are translated into a changing spatial pattern of land use. Our study focused on a portion of the Chesapeake Bay Watershed where the spatial patterns of sprawl represent a set of conditions generally prevalent in much of the U.S. Working in the region permitted us access to (i) a time-series of multi-scale and multi-temporal (including historical) satellite imagery and (ii) an established network of collaborating partners and agencies willing to share resources and to utilize developed techniques and model results. In addition, a unique parcel-level tax assessment database and linked parcel boundary maps exists for two counties in the Maryland portion of this region that made it possible to establish a historical cross-section time-series database of parcel level development decisions. Scenario analyses of future land use dynamics provided critical quantitative insight into the impact of alternative land management and policy decisions. These also have been specifically aimed at addressing growth control policies aimed at curbing exurban (sprawl) development. Our initial technical approach included three components: (i) spatial econometric modeling of the development decision, (ii) remote sensing of suburban change and residential land use density, including comparisons of past change from Landsat analyses and more traditional sources, and (iii) linkages between the two through variable initialization and supplementation of parcel level data. To these we added a fourth component, (iv) cellular automata modeling of urbanization, which proved to be a valuable addition to the project. This project has generated both remote sensing and spatially explicit socio-economic data to estimate and calibrate the parameters for two different types of land use change models and has

  19. Spatio-Temporal Mechanistic Watershed Modeling of Mercury, Carbon, and Nitrogen Fate and Transport in a Coastal Plain Watershed (McTier Creek watershed, SC, USA)

    NASA Astrophysics Data System (ADS)

    Knightes, C. D.; Golden, H. E.; Davis, G. M.; Bradley, P. M.; Journey, C.; Conrads, P. A.; Brigham, M. E.

    2011-12-01

    The Coastal Plain of the US is a hotspot of methylmercury (MeHg) production and bioaccumulation due to the mix of high Hg deposition, widespread wetland coverage, and high DOC and/or acidic surface waters. However, research in mercury fate and transport is just recently emerging in this region. Although atmospheric deposition is the primary source of mercury to many aquatic ecosystems, there is little understanding and associated modeling representation of how atmospherically deposited mercury transports and transforms within the watershed on its way to receiving streams, particularly within watersheds with different drainage areas within similar physiographical provinces. In this study, we examine mercury and linked biogeochemical cycling (nitrogen (N) and carbon (C)) cycling at a variety of spatial scales within a set of nested sub-basins of the McTier Creek watershed, South Carolina, which is located in the upper Coastal Plain of the Southeastern US. Our goal is to advance current understanding of mercury dynamics in the Coastal Plain and discern important processes governing multi-scale transformation, fate, and transport of mercury. We apply a spatially-explicit, linked process-based watershed hydrology and biogeochemical cycling (N, C, and Hg) model (Visualizing Ecosystems for Land Management Assessment; VELMA) to predict daily flow and daily fluxes and concentrations of total mercury (THg), methylmercury (MeHg), dissolved organic carbon (DOC), dissolved inorganic nitrogen (DIN), and dissolved organic nitrogen (DON). The modeling effort was performed in concert with a rigorous sampling effort as part of the USGS NAWQA Mercury in Stream Ecosystems Program. VELMA was applied at a series of different scales including a focused reach (0.11 km^2), two sub-watersheds (28 km^2, 24 km^2) and the full watershed (79.4 km^2). We scale VELMA parameterization and processes occurring within the focused study reach to the larger sub-watersheds to investigate how well the

  20. Reconstructing pre-colonial oyster demographics in the Chesapeake Bay, USA

    NASA Astrophysics Data System (ADS)

    Mann, Roger; Harding, Juliana M.; Southworth, Melissa J.

    2009-11-01

    Recent estimates of growth and mortality rates in extant Chesapeake Bay, USA oyster ( Crassostrea virginica) populations are used to quantify changes in both population abundance (dN/dT) and shell accretion (dS/dT) associated with modern population demographics. The demographics of oyster populations that would be required to maintain reef accretion rates commensurate with sea level rise over geological time frames are examined using estimates of oyster longevity in pre-colonial (pre -1600) times combined with parallel estimates of pre-disease endemic mortality. The analysis demonstrates that modern populations, with their disease related, age-truncated demographics, are generally not capable of maintaining and building biogenic reefs through accretion. Estimates of filtration rates associated with Chesapeake Bay oyster populations prior to 1600 considerably underestimate actual benthic-pelagic coupling during that period. Pristine oyster populations would have supported water column turnover rates on the order of minutes to hours. Thus, the spatial footprint of oyster reefs was limited by available productivity in the estuary. Accretion rate calculations for pristine (pre-1600) oyster reefs describe the intimate relationship between benthic-pelagic coupling and the presence or absence of oyster reefs and the associated communities.

  1. Rising air and stream-water temperatures in Chesapeake Bay region, USA

    USGS Publications Warehouse

    Rice, Karen C.; Jastram, John D.

    2015-01-01

    Monthly mean air temperature (AT) at 85 sites and instantaneous stream-water temperature (WT) at 129 sites for 1960–2010 are examined for the mid-Atlantic region, USA. Temperature anomalies for two periods, 1961–1985 and 1985–2010, relative to the climate normal period of 1971–2000, indicate that the latter period was statistically significantly warmer than the former for both mean AT and WT. Statistically significant temporal trends across the region of 0.023 °C per year for AT and 0.028 °C per year for WT are detected using simple linear regression. Sensitivity analyses show that the irregularly sampled WT data are appropriate for trend analyses, resulting in conservative estimates of trend magnitude. Relations between 190 landscape factors and significant trends in AT-WT relations are examined using principal components analysis. Measures of major dams and deciduous forest are correlated with WT increasing slower than AT, whereas agriculture in the absence of major dams is correlated with WT increasing faster than AT. Increasing WT trends are detected despite increasing trends in streamflow in the northern part of the study area. Continued warming of contributing streams to Chesapeake Bay likely will result in shifts in distributions of aquatic biota and contribute to worsened eutrophic conditions in the bay and its estuaries.

  2. Impact of storm-water outfalls on sediment quality in Corpus Christi Bay, Texas, USA

    SciTech Connect

    Carr, R.S.; Montagna, P.A.; Biedenbach, J.M.; Kalke, R.; Kennicutt, M.C.; Hooten, R.; Cripe, G.

    2000-03-01

    To determine the quality of sediments and extent of contaminant impacts, a Sediment Quality Triad (SQT) study was conducted at 36 sites in the Corpus Christi Bay, Texas, USA, system. Fifteen of the 36 sites were located near storm-water outfalls, but 13 other sites (i.e., industrial and domestic outfalls, oil field-produced water discharges, and dredging activity) and eight reference sites were also evaluated. Sediment samples were collected and analyzed for physical-chemical characteristics, contaminant concentrations (metals, polycyclic aromatic hydrocarbons [PAHs], polychlorinated biphenyls [PCBs], and pesticides), toxicity, and a benthic index of biotic integrity (BIBI) composed of 10 independent metrics calculated for each site. This large data matrix was reduced using multivariate analysis to create new variables for each component representing overall means and containing most of the variance in the larger data set. The new variables were used to conduct the correlation analysis. Toxicity was significantly correlated with both chemistry and ecological responses, whereas no correlations between the benthic metrics and sediment chemistry were observed. Using the combined information from the SQT, four of the five most degraded sites were storm-water outfall sites. Although estuaries are naturally stressful environments because of salinity and temperature fluctuations, this ecosystem appears to have been compromised by anthropogenic influences similar to what has been observed for other heavily urbanized bay systems along the Texas and Gulf coast.

  3. Impact of storm-water outfalls on sediment quallity in corpus Christi Bay, Texas, USA

    USGS Publications Warehouse

    Carr, R. Scott; Montagna, Paul A.; Biedenbach, James M.; Kalke, Rick; Kennicutt, Mahlon C.; Hooten, Russell L.; Cripe, Geraldine

    2000-01-01

    To determine the quality of sediments and extent of contaminant impacts, a Sediment Quality Triad (SQT) study was conducted at 36 sites in the Corpus Christi Bay, Texas, USA, system. Fifteen of the 36 sites were located near storm-water outfalls, but 13 other sites (i.e., industrial and domestic outfalls, oil field–produced water discharges, and dredging activity) and eight reference sites were also evaluated. Sediment samples were collected and analyzed for physical–chemical characteristics, contaminant concentrations (metals, polycyclic aromatic hydrocarbons [PAHs], polychlorinated biphenyls [PCBs], and pesticides), toxicity (amphipod and mysid solid phase and sea urchin pore-water fertilization and embryological development tests), and a benthic index of biotic integrity (BIBI) composed of 10 independent metrics calculated for each site. This large data matrix was reduced using multivariate analysis to create new variables for each component representing overall means and containing most of the variance in the larger data set. The new variables were used to conduct the correlation analysis. Toxicity was significantly correlated with both chemistry and ecological responses, whereas no correlations between the benthic metrics and sediment chemistry were observed. Using the combined information from the SQT, four of the five most degraded sites were storm-water outfall sites. Although estuaries are naturally stressful environments because of salinity and temperature fluctuations, this ecosystem appears to have been compromised by anthropogenic influences similar to what has been observed for other heavily urbanized bay systems along the Texas and Gulf coast.

  4. Organochlorine contaminants and reproductive success of double-crested cormorants from Green Bay, Wisconsin, USA

    USGS Publications Warehouse

    Custer, T.W.; Custer, Christine M.; Hines, R.K.; Gutreuter, S.; Stromborg, K.L.; Allen, P.D.; Melancon, M.J.

    1999-01-01

    In 1994 and 1995, nesting success of double-crested cormorants (Phalacrocorax auritus) was measured at Cat Island, in southern Green Bay, Lake Michigan, Wisconsin, USA. Sample eggs at pipping and unhatched eggs were collected and analyzed for organochlorines (including total polychlorinated biphenyls [PCBs] and DDE), hepatic microsomal ethoxyresorufin-O-dealkylase (EROD) activity in embryos, and eggshell thickness. Of 1,570 eggs laid, 32% did not hatch and 0.4% had deformed embryos. Of 632 chicks monitored from hatching to 12 d of age, 9% were missing or found dead; no deformities were observed. The PCB concentrations in sample eggs from clutches with deformed embryos (mean = 10.2 μg/g wet weight) and dead embryos (11.4 μg/g) were not significantly higher than concentrations in sample eggs from nests where all eggs hatched (12.1 μg/g). A logistic regression of hatching success versus DDE, dieldrin, and PCB concentrations in sibling eggs identified DDE and not dieldrin or PCBs as a significant risk factor. A logistic regression of hatching success versus DDE and eggshell thickness implicated DDE and not eggshell thickness as a significant risk factor. Even though the insecticide DDT was banned in the early 1970s, we suggest that DDE concentrations in double-crested cormorant eggs in Green Bay are still having an effect on reproduction in this species.

  5. Spatial and temporal trends in runoff at long-term streamgages within and near the Chesapeake Bay Watershed

    USGS Publications Warehouse

    Rice, Karen C.; Hirsch, Robert M.

    2012-01-01

    Long-term streamflow data within the Chesapeake Bay watershed and surrounding area were analyzed in an attempt to identify trends in streamflow. Data from 30 streamgages near and within the Chesapeake Bay watershed were selected from 1930 through 2010 for analysis. Streamflow data were converted to runoff and trend slopes in percent change per decade were calculated. Trend slopes for three runoff statistics (the 7-day minimum, the mean, and the 1-day maximum) were analyzed annually and seasonally. The slopes also were analyzed both spatially and temporally. The spatial results indicated that trend slopes in the northern half of the watershed were generally greater than those in the southern half. The temporal analysis was done by splitting the 80-year flow record into two subsets; records for 28 streamgages were analyzed for 1930 through 1969 and records for 30 streamgages were analyzed for 1970 through 2010. The mean of the data for all sites for each year were plotted so that the following datasets were analyzed: the 7-day minimum runoff for the north, the 7-day minimum runoff for the south, the mean runoff for the north, the mean runoff for the south, the 1-day maximum runoff for the north, and the 1-day maximum runoff for the south. Results indicated that the period 1930 through 1969 was statistically different from the period 1970 through 2010. For the 7-day minimum runoff and the mean runoff, the latter period had significantly higher streamflow than did the earlier period, although within those two periods no significant linear trends were identified. For the 1-day maximum runoff, no step trend or linear trend could be shown to be statistically significant for the north, although the south showed a mixture of an upward step trend accompanied by linear downtrends within the periods. In no case was a change identified that indicated an increasing rate of change over time, and no general pattern was identified of hydrologic conditions becoming "more extreme

  6. Geochemical fine-sediment tracers in San Francisco Bay and its outer coast: the role of local watersheds

    NASA Astrophysics Data System (ADS)

    Takesue, R. K.; Barnard, P. L.

    2012-12-01

    Sediment enters San Francisco Bay (SFB) through the Sacramento-San Joaquin River Delta, the Golden Gate, and local watersheds. Inputs from local watersheds have become increasingly important since the 1940s when large-scale impoundments began upstream of the Delta. The goals of this study are to determine whether fine sediment from local watersheds have distinct geochemical signatures, and if these can be used to determine whether locally-derived sediment accumulates in SFB. Retention of fine sediment is essential if accretion of shallow and intertidal habitats is to keep pace with sea level rise. Total contents of chromium (Cr), lanthanum (La), thorium (Th), zirconium (Zr), rare earth elements (REE), and twenty five other elements were determined by ICP-MS in the fine or "mud" fraction (<63 μm) of river, tributary, bay, and outer coast bed sediment. SFB and outer coast sediment was collected in January 2012 after a 5-day storm. River and tributary sediment was collected between 2010-2012. REE contents were normalized to a shale composite (NASC). In comparison to granitic material from the Sierra Nevada, local watersheds contain ultramafic Franciscan rocks in the Coast Range, volcanic deposits near Napa and Sonoma, and ancient marine sedimentary rocks. Fine sediment from the Sacramento River was enriched in heavy REE (HREENASC) and Cr, while that from the San Joaquin River was enriched in light REE (LREENASC) and Th. Petaluma River and Sonoma Creek fine sediments were distinguished by middle REE (MREENASC) enrichments and low Cr contents consistent with felsic volcanic rocks. In contrast, fine sediments in Napa River and Wildcat Creek had relatively flat REENASC patterns and intermediate to high Cr contents that suggest a Franciscan influence. The same was true for fine sediment in Marin creeks (Arroyo del Presidio and Corte Madera) and two South Bay tributaries (Guadelupe River and San Francisquito Creek). San Francisquito Creek fine sediment was uniquely

  7. Impacts of Watershed Characteristics and Crop Rotations on Winter Cover Crop Nitrate-Nitrogen Uptake Capacity within Agricultural Watersheds in the Chesapeake Bay Region

    PubMed Central

    Lee, Sangchul; Yeo, In-Young; Sadeghi, Ali M.; McCarty, Gregory W.; Hively, W. Dean; Lang, Megan W.

    2016-01-01

    The adoption rate of winter cover crops (WCCs) as an effective conservation management practice to help reduce agricultural nutrient loads in the Chesapeake Bay (CB) is increasing. However, the WCC potential for water quality improvement has not been fully realized at the watershed scale. This study was conducted to evaluate the long-term impact of WCCs on hydrology and NO3-N loads in two adjacent watersheds and to identify key management factors that affect the effectiveness of WCCs using the Soil and Water Assessment Tool (SWAT) and statistical methods. Simulation results indicated that WCCs are effective for reducing NO3-N loads and their performance varied based on planting date, species, soil characteristics, and crop rotations. Early-planted WCCs outperformed late-planted WCCs on the reduction of NO3-N loads and early-planted rye (RE) reduced NO3-N loads by ~49.3% compared to the baseline (no WCC). The WCCs were more effective in a watershed dominated by well-drained soils with increased reductions in NO3-N fluxes of ~2.5 kg N·ha-1 delivered to streams and ~10.1 kg N·ha-1 leached into groundwater compared to poorly-drained soils. Well-drained agricultural lands had higher transport of NO3-N in the soil profile and groundwater due to increased N leaching. Poorly-drained agricultural lands had lower NO3-N due to extensive drainage ditches and anaerobic soil conditions promoting denitrification. The performance of WCCs varied by crop rotations (i.e., continuous corn and corn-soybean), with increased N uptake following soybean crops due to the increased soil mineral N availability by mineralization of soybean residue compared to corn residue. The WCCs can reduce N leaching where baseline NO3-N loads are high in well-drained soils and/or when residual and mineralized N availability is high due to the cropping practices. The findings suggested that WCC implementation plans should be established in watersheds according to local edaphic and agronomic

  8. Factors Influencing Watershed Average Erosion Rates Calculated from Reservoir Sedimentation in Eastern USA

    NASA Astrophysics Data System (ADS)

    Ahamed, A.; Snyder, N. P.; David, G. C.

    2014-12-01

    The Reservoir Sedimentation Database (ResSed), a catalogue of reservoirs and depositional data that has recently become publically available, allows for rapid calculation of sedimentation rates and rates of capacity loss over short (annual to decadal) timescales. This study is a statistical investigation of factors controlling watershed average erosion rates (E) in eastern United States watersheds. We develop an ArcGIS-based model that delineates watersheds upstream of ResSed dams and calculate drainage areas to determine E for 191 eastern US watersheds. Geomorphic, geologic, regional, climatic, and land use variables are quantified within study watersheds using GIS. Erosion rates exhibit a large amount of scatter, ranging from 0.001 to 1.25 mm/yr. A weak inverse power law relationship between drainage area (A) and E (R2 = 0.09) is evident, similar to other studies (e.g. Milliman and Syvitski, 1992; Koppes and Montgomery, 2009). Linear regressions reveal no relationship between mean watershed slope (S) and E, possibly due to the relatively low relief of the region (mean S for all watersheds is 6°). Analysis of Variance shows that watersheds in formerly glaciated regions exhibit a statistically significant lower mean E (0.06 mm/year) than watersheds in unglaciated regions (0.12 mm/year), but that watersheds with different dam purposes show no significant differences in mean E. Linear regressions reveal no relationships between E and land use parameters like percent agricultural land and percent impervious surfaces (I), but classification and regression trees indicate that watersheds in highly developed regions (I > 34%) exhibit mean E (0.36 mm/year) that is four times higher than watersheds in less developed (I < 34%) regions (0.09 mm/year). Further, interactions between land use variables emerge in formerly glaciated regions, where increased agricultural land results in higher rates of annual capacity loss in reservoirs (R2 = 0.56). Plots of E versus timescale of

  9. Hydrology and water quality of a field and riparian buffer adjacent to a mangrove wetland in Jobos Bay Watershed, Puerto Rico

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Models that estimate the effects of agricultural conservation practices on water quantity and quality have become increasingly important tools for short- and long-term assessments. In this study, we simulated the water quality and hydrology of a portion of the Jobos Bay watershed, Puerto Rico using...

  10. Diagnosis of potential stressors adversely affecting benthic invertebrate communities in Greenwich Bay, Rhode Island, USA

    EPA Science Inventory

    Greenwich Bay is an urbanized embayment of Narragansett Bay potentially impacted by multiple stressors. The present study identified the important stressors affecting Greenwich Bay benthic fauna. First, existing data and information were used to confirm that the waterbody was imp...

  11. Best management practices for reducing nutrient loads in a sub-watershed of Chesapeake Bay

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Water quality improvement in the Chesapeake Bay is a grave concern. An initiative to reduce the nutrient loads to stream has been undertaken to attain a target total maximum daily load (TMDL) at Chesapeake Bay. A general guideline with a set of best management practices (BMPs) has been in place for ...

  12. Best management practices for reducing nutrient loads in a sub-watershed of Chesapeake Bay area

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Water quality improvement in the Chesapeake Bay is a grave concern. An initiative to reduce the nutrient loads to stream has been undertaken to attain a target total maximum daily load (TMDL) at Chesapeake Bay. A general guideline with a set of best management practices (BMPs) has been in place for ...

  13. Importance of Watershed Land Use in Predicting Benthic Invertebrate Condition in the Virginian Biogeographic Province, USA.

    EPA Science Inventory

    Estuaries are dynamic transition zones linking freshwater and oceanic habitats. These productive ecosystems are threatened by a variety of stressors including human modification of coastal watersheds. In this study we examined potential linkages between estuarine condition and...

  14. Advancing the Guánica Bay (Puerto Rico) Watershed Management Plan

    EPA Science Inventory

    Consideration of stakeholder values in watershed planning and management is a necessity, but sufficiently eliciting, understanding, and organizing those values can be daunting. Many studies have demonstrated the usefulness of formal decision analysis to integrate expert knowledge...

  15. Evaluation of land use and water quality in an agricultural watershed in the USA indicates multiple sources of bacterial impairment.

    PubMed

    Wittman, Jacob; Weckwerth, Andrew; Weiss, Chelsea; Heyer, Sharon; Seibert, Jacob; Kuennen, Ben; Ingels, Chad; Seigley, Lynette; Larsen, Kirk; Enos-Berlage, Jodi

    2013-12-01

    Pathogens are the number one cause of impairments of assessed rivers and streams in the USA and pose a significant human health hazard. The Dry Run Creek Watershed in Northeast Iowa has been designated as impaired by the State of Iowa because of high levels of Escherichia coli bacteria. To investigate the nature of this impairment, land use and stream bank assessments were coupled with comprehensive water quality monitoring. Physical, chemical, and biological parameters were measured at 13 different sites in the watershed, including pH, temperature, conductivity, dissolved oxygen, turbidity, total Kjeldahl nitrogen, ammonia-N, nitrate + nitrite-N, total phosphorus, and E. coli. In addition, benthic macroinvertebrate communities were analyzed at seven sites, and optical brightener tests were performed late in the season. Results identified segments of the watershed that were more prominent contributors of E. coli, and correlations were observed between levels of E. coli and several chemical parameters, including ammonia-N, total Kjeldahl nitrogen, and total phosphorus. Interestingly, distinct sites emerged as more prominent contributors of these elements during rain vs. non-rain events, suggesting different types of sources. Both the amount of rainfall and the time elapsed between the rain event and the sampling influenced E. coli levels during wet weather conditions. Nitrate + nitrite-N displayed a unique response to rain events compared with the other parameters, suggesting a different delivery route. Analyses of benthic macroinvertebrate communities were consistent with pollution trends. Collectively, these data suggest distinct agriculturally related E. coli contributions, as well as specific areas and practices for water quality improvement strategies. This study can serve as a resource for evaluating agricultural watersheds that are impaired for bacteria.

  16. Predicted impact of transgenic, herbicidetolerant corn on drinking water quality in vulnerable watersheds of the mid-western USA.

    PubMed

    Wauchope, R Don; Estes, Tammara L; Allen, Richard; Baker, James L; Hornsby, Arthur G; Jones, Russell L; Richards, R Peter; Gustafson, David I

    2002-02-01

    In the intensely farmed corn-growing regions of the mid-western USA, surface waters have often been contaminated by herbicides, principally as a result of rainfall runoff occurring shortly after application of these to corn and other crops. In some vulnerable watersheds, water quality criteria for chronic human exposure through drinking water are occasionally exceeded. We selected three settings representative of vulnerable corn-region watersheds, and used the PRZM-EXAMS model with the Index Reservoir scenario to predict corn herbicide concentrations in the reservoirs as a function of herbicide properties and use pattern, site characteristics and weather in the watersheds. We compared herbicide application scenarios, including broadcast surface pre-plant atrazine and alachlor applications with a glyphosate pre-plant application, scenarios in which losses of herbicides were mitigated by incorporation or banding, and scenarios in which only glyphosate or glufosinate post-emergent herbicides were used with corn genetically modified to be resistant to them. In the absence of drift, in almost all years a single runoff event dominates the input into the reservoir. As a result, annual average pesticide concentrations are highly correlated with annual maximum daily values. The modeled concentrations were generally higher than those derived from monitoring data, even for no-drift model scenarios. Because of their lower post-emergent application rates and greater soil sorptivity, glyphosate and glufosinate loads in runoff were generally one-fifth to one-tenth those of atrazine and alachlor. These model results indicate that the replacement of pre-emergent corn herbicides with the post-emergent herbicides allowed by genetic modification of crops would dramatically reduce herbicide concentrations in vulnerable watersheds. Given the significantly lower chronic mammalian toxicity of these compounds, and their vulnerability to breakdown in the drinking water treatment process

  17. Feasibility Study of Carbon Sequestration Through Reforestation in the Chesapeake Bay Watershed of Virginia

    SciTech Connect

    Andy Lacatell; David Shoch; Bill Stanley; Zoe Kant

    2007-03-01

    The Chesapeake Rivers conservation area encompasses approximately 2,000 square miles of agricultural and forest lands in four Virginia watersheds that drain to the Chesapeake Bay. Consulting a time series of classified Landsat imagery for the Chesapeake Rivers conservation area, the project team developed a GIS-based protocol for identifying agricultural lands that could be reforested, specifically agricultural lands that had been without forest since 1990. Subsequent filters were applied to the initial candidate reforestation sites, including individual sites > 100 acres and sites falling within TNC priority conservation areas. The same data were also used to produce an analysis of baseline changes in forest cover within the study period. The Nature Conservancy and the Virginia Department of Forestry identified three reforestation/management models: (1) hardwood planting to establish old-growth forest, (2) loblolly pine planting to establish working forest buffer with hardwood planting to establish an old-growth core, and (3) loblolly pine planting to establish a working forest. To assess the relative carbon sequestration potential of these different strategies, an accounting of carbon and total project costs was completed for each model. Reforestation/management models produced from 151 to 171 tons carbon dioxide equivalent per acre over 100 years, with present value costs of from $2.61 to $13.28 per ton carbon dioxide equivalent. The outcome of the financial analysis was especially sensitive to the land acquisition/conservation easement cost, which represented the most significant, and also most highly variable, single cost involved. The reforestation/management models explored all require a substantial upfront investment prior to the generation of carbon benefits. Specifically, high land values represent a significant barrier to reforestation projects in the study area, and it is precisely these economic constraints that demonstrate the economic additionality

  18. Polychlorinated Biphenyls (PCBs) and Polybrominated Diphenol Ethers (PBDEs) in Current and Historical Samples of Avian Eggs from Nesting Sites in Buzzards Bay, MA, USA

    EPA Science Inventory

    We measured concentrations of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in eggs from breeding colonies in Buzzards Bay, MA, USA. Eggs from two piscivorous bird species, common (Sterna hirundo) and roseate (Sterna dougallii) terns, were collected...

  19. Molecular and morphological diversity of Narragansett Bay (RI, USA) Ulva (Ulvales, Chlorophyta) populations.

    PubMed

    Guidone, Michele; Thornber, Carol; Wysor, Brian; O'Kelly, Charles J

    2013-10-01

    Macroalgal bloom-forming species occur in coastal systems worldwide. However, due to overlapping morphologies in some taxa, accurate taxonomic assessment and classification of these species can be quite challenging. We investigated the molecular and morphological characteristics of 153 specimens of bloom-forming Ulva located in and around Narragansett Bay, RI, USA. We analyzed sequences of the nuclear internal transcribed spacer 1 region (ITS1) and the chloroplast-encoded rbcL; based on the ITS1 data, we grouped the specimens into nine operational taxonomic units (OTUs). Eight of these OTUs have been previously reported to exist, while one is novel. Of the eight OTUs, all shared sequence identity with previously published sequences or differed by less than 1.5% sequence divergence for two molecular markers. Previously, 10 species names were reported for Ulva in Rhode Island (one blade and nine tube-forming species) based upon morphological classification alone. Of our nine OTUs, three contained blade-forming specimens (U. lactuca, U. compressa, U. rigida), one OTU had a blade with a tubular stipe, and six contained unbranched and/or branched tubular morphologies (one of these six, U. compressa, had both a blade and a tube morphology). While the three blade-forming OTUs in Narragansett Bay can frequently be distinguished by careful observations of morphological characteristics, and spatial/temporal distribution, it is much more difficult to distinguish among the tube-forming specimens based upon morphology or distribution alone. Our data support the molecular species concept for Ulva, and indicate that molecular-based classifications of Ulva species are critical for proper species identification, and subsequent ecological assessment or mitigation of Ulva blooms.

  20. Concurrent Exposure of Bottlenose Dolphins (Tursiops truncatus) to Multiple Algal Toxins in Sarasota Bay, Florida, USA

    PubMed Central

    Twiner, Michael J.; Fire, Spencer; Schwacke, Lori; Davidson, Leigh; Wang, Zhihong; Morton, Steve; Roth, Stephen; Balmer, Brian; Rowles, Teresa K.; Wells, Randall S.

    2011-01-01

    Sentinel species such as bottlenose dolphins (Tursiops truncatus) can be impacted by large-scale mortality events due to exposure to marine algal toxins. In the Sarasota Bay region (Gulf of Mexico, Florida, USA), the bottlenose dolphin population is frequently exposed to harmful algal blooms (HABs) of Karenia brevis and the neurotoxic brevetoxins (PbTx; BTX) produced by this dinoflagellate. Live dolphins sampled during capture-release health assessments performed in this region tested positive for two HAB toxins; brevetoxin and domoic acid (DA). Over a ten-year study period (2000–2009) we have determined that bottlenose dolphins are exposed to brevetoxin and/or DA on a nearly annual basis (i.e., DA: 2004, 2005, 2006, 2008, 2009; brevetoxin: 2000, 2004, 2005, 2008, 2009) with 36% of all animals testing positive for brevetoxin (n = 118) and 53% positive for DA (n = 83) with several individuals (14%) testing positive for both neurotoxins in at least one tissue/fluid. To date there have been no previously published reports of DA in southwestern Florida marine mammals, however the May 2008 health assessment coincided with a Pseudo-nitzschia pseudodelicatissima bloom that was the likely source of DA observed in seawater and live dolphin samples. Concurrently, both DA and brevetoxin were observed in common prey fish. Although no Pseudo-nitzschia bloom was identified the following year, DA was identified in seawater, fish, sediment, snails, and dolphins. DA concentrations in feces were positively correlated with hematologic parameters including an increase in total white blood cell (p = 0.001) and eosinophil (p<0.001) counts. Our findings demonstrate that dolphins within Sarasota Bay are commonly exposed to two algal toxins, and provide the impetus to further explore the potential long-term impacts on bottlenose dolphin health. PMID:21423740

  1. Bed composition generation for morphodynamic modeling: Case study of San Pablo Bay in California, USA

    USGS Publications Warehouse

    van der Wegen, M.; Dastgheib, A.; Jaffe, B.E.; Roelvink, D.

    2011-01-01

    Applications of process-based morphodynamic models are often constrained by limited availability of data on bed composition, which may have a considerable impact on the modeled morphodynamic development. One may even distinguish a period of "morphodynamic spin-up" in which the model generates the bed level according to some ill-defined initial bed composition rather than describing the realistic behavior of the system. The present paper proposes a methodology to generate bed composition of multiple sand and/or mud fractions that can act as the initial condition for the process-based numerical model Delft3D. The bed composition generation (BCG) run does not include bed level changes, but does permit the redistribution of multiple sediment fractions over the modeled domain. The model applies the concept of an active layer that may differ in sediment composition above an underlayer with fixed composition. In the case of a BCG run, the bed level is kept constant, whereas the bed composition can change. The approach is applied to San Pablo Bay in California, USA. Model results show that the BCG run reallocates sand and mud fractions over the model domain. Initially, a major sediment reallocation takes place, but development rates decrease in the longer term. Runs that take the outcome of a BCG run as a starting point lead to more gradual morphodynamic development. Sensitivity analysis shows the impact of variations in the morphological factor, the active layer thickness, and wind waves. An important but difficult to characterize criterion for a successful application of a BCG run is that it should not lead to a bed composition that fixes the bed so that it dominates the "natural" morphodynamic development of the system. Future research will focus on a decadal morphodynamic hindcast and comparison with measured bathymetries in San Pablo Bay so that the proposed methodology can be tested and optimized. ?? 2010 The Author(s).

  2. Horseshoe crab spawning activity in Delaware Bay, USA, after harvest reduction: A mixed-model analysis

    USGS Publications Warehouse

    Smith, David; Robinson, Timothy J.

    2015-01-01

    A Delaware Bay, USA, standardized survey of spawning horseshoe crabs, Limulus polyphemus, was carried out in 1999 − 2013 through a citizen science network. Previous trend analyses of the data were at the state (DE or NJ) or bay-wide levels. Here, an alternative mixed-model regression analysis was used to estimate trends in female and male spawning densities at the beach level (n = 26) with the objective of inferring their causes. For females, there was no overall trend and no single explanation applies to the temporal and spatial patterns in their densities. Individual beaches that initially had higher densities tended to experience a decrease, while beaches that initially had lower densities tended to experience an increase. As a result, densities of spawning females at the end of the study period were relatively similar among beaches, suggesting a redistribution of females among the beaches over the study period. For males, there was a positive overall trend in spawning abundance from 1999 to 2013, and this increase occurred broadly among beaches. Moreover, the beaches with below-average initial male density tended to have the greatest increases. Possible explanations for these patterns include harvest reduction, sampling artifact, habitat change, density-dependent habitat selection, or mate selection. The broad and significant increase in male spawning density, which occurred after enactment of harvest controls, is consistent with the harvest reduction explanation, but there is no single explanation for the temporal or spatial pattern in female densities. These results highlight the continued value of a citizen-science-based spawning survey in understanding horseshoe crab ecology and conservation.

  3. Thin layers and species-specific characterization of the phytoplankton community in Monterey Bay, California, USA

    NASA Astrophysics Data System (ADS)

    Rines, J. E. B.; McFarland, M. N.; Donaghay, P. L.; Sullivan, J. M.

    2010-01-01

    During the summers of 2005 and 2006, experiments designed to understand the properties of densely concentrated, thin layers of plankton and the processes governing their dynamics were conducted in Monterey Bay, California, USA. Our goal was to elucidate the role that species-specific properties of phytoplankton play in thin layer dynamics. Using adaptive sampling, we collected water samples from inside and outside bio-optical features of the water column. Characterization of the phytoplankton was compiled from live and preserved samples, and analyzed within a framework of physical, optical, chemical and acoustical data. In both years, Monterey Bay was home to an extraordinarily diverse assemblage of phytoplankton and other protists. Bioluminescent dinoflagellates, and Harmful Algal Bloom (HAB) taxa were common. In 2005, community assemblages were widespread, thus advection of water through the experimental mooring array did not result in floristic changes. In 2006 phytoplankton were very patchy in horizontal distribution, and advection of water through the array was at times accompanied by dramatic shifts in community composition. Individual taxa often exhibited disparate patterns of vertical distribution, with some found throughout the water column, whereas others were restricted to narrow depth intervals. Thin layers were observed in both years. In 2005, the dinoflagellate Akashiwo sanguinea formed intense thin layers near the pycnocline at night, and migrated to near surface waters at dawn. In 2006, layer composition was more complex, and related to the water mass present at the time of sampling. Optically detected thin layers of phytoplankton can be studied from the perspective of the impact their high biomass has on both ecological processes, and ocean optics. But thin layers can also be studied from the species-specific perspective of each organism, its role within the thin layer habitat, and the impact that life within a thin layer has on its life history

  4. Mercury correlations among six tissues for four waterbird species breeding in San Francisco Bay, California, USA

    USGS Publications Warehouse

    Eagles-Smith, C. A.; Ackerman, J.T.; Adelsbach, T.L.; Takekawa, J.Y.; Miles, A.K.; Keister, R.A.

    2008-01-01

    Despite a large body of research concerning mercury (Hg) in birds, no single tissue has been used consistently to assess Hg exposure, and this has hampered comparisons across studies. We evaluated the relationships of Hg concentrations among tissues in four species of waterbirds (American avocets [Recurvirostra americana], black-necked stilts [Himantopus mexicanus], Caspian terns [Hydroprogne caspia; formerly Sterna caspia], and Forster's terns [Sterna forsteri]) and across three life stages (prebreeding adults, breeding adults, and chicks) in San Francisco Bay, California, USA. Across species and life stages, Hg concentrations (least square mean ?? standard error) were highest in head feathers (6.45 ?? 0.31 ??g/g dry wt) and breast feathers (5.76 ?? 0.28 ??g/g dry wt), followed by kidney (4.54 ?? 0.22 ??g/g dry wt), liver (4.43 ?? 0.21 ??g/g dry wt), blood (3.10 ?? 0.15 ??g/g dry wt), and muscle (1.67 ?? 0.08 ??g/g dry wt). Relative Hg distribution among tissues, however, differed by species and life stage. Mercury concentrations were highly correlated among internal tissues (r 2 ??? 0.89). Conversely, the relationships between Hg in feathers and internal tissues were substantially weaker (r2 ??? 0.42). Regression slopes sometimes differed among species and life stages, indicating that care must be used when predicting Hg concentrations in one tissue based on those in another. However, we found good agreement between predictions made using a general tissue-prediction equation and more specific equations developed for each species and life stage. Finally, our results suggest that blood is an excellent, nonlethal predictor of Hg concentrations in internal tissues but that feathers are relatively poor indicators of Hg concentrations in internal tissues. ?? 2008 SETAC Printed in the USA.

  5. A simulation of groundwater discharge and nitrate delivery to chesapeake bay from the lowermost delmarva peninsula, USA

    USGS Publications Warehouse

    Sanford, W.E.; Pope, J.P.

    2007-01-01

    A groundwater model has been developed for the lowermost Delmarva Peninsula, USA, that simulates saltwater intrusion into local confined aquifers and nitrate delivery to the Chesapeake Bay from the surficial aquifer. A flow path and groundwater-age analysis was performed using the model to estimate the timing of nitrate delivery to the bay over the next several decades. The simulated mean and median residence times of groundwater in the lowermost peninsula are 30 and 15 years, respectively. Current and future nitrate concentrations in coastal groundwater discharge were simulated based on local well data that include nitrate concentrations and groundwater age. A simulated future-trends analysis indicates that nitrate that has been applied to agricultural regions over the last few decades will continue to discharge into the bay for several decades to come. This study highlights the importance of considering the groundwater lag time that affects the mean transport time from diffuse contamination sources.

  6. Relationships between clay mineralogy, hydrothermal metamorphism, and topography in a Western Cascades watershed, Oregon, USA

    NASA Astrophysics Data System (ADS)

    Ambers, Rebecca K. R.

    2001-05-01

    This study investigates variation in clay mineralogy and its relation to hydrothermal metamorphism, hillslope processes, and topography in the western Cascade Mountains. The study area is the drainage basin of Dorena Lake, a medium-sized (686 km 2) watershed located near Cottage Grove, OR. The Bohemia Mining District is on the southeastern rim of the watershed in a hydrothermally metamorphosed region associated with a set of granodiorite plutons. To characterize large-scale patterns of clay mineral distribution within the watershed, suspended sediments were collected from 43 stream locations. Samples of several metamorphosed and unaffected volcanic and volcaniclastic rocks were collected to help clarify metamorphic reaction processes. One active earthflow was also sampled. X-ray diffraction methods were used to determine the mineralogy of the clay-sized (<2 μm) fraction of the samples. Clay mineralogy varies systematically across the watershed, and the three major stream tributaries carry sediment with distinct mineralogical signatures. Discrete minerals include kaolinite, smectite, chlorite, and illite. Interstratified kaolinite-smectite and chlorite-vermiculite (CV) are also present. The active earthflow and unmetamorphosed rock samples primarily contain smectite. In contrast, metamorphosed rock samples are composed of some combination of illite, interstratified illite-smectite, CV, and chlorite. Examination of clay mineral distribution reveals the effects of hydrothermal metamorphism in the mining district on clay mineralogy, hillslope processes, and landscape development. Compared with most of the watershed, the mining district has steeper slopes and higher elevations and lacks smectite almost entirely. Analyses of metamorphosed bedrock units indicate that smectite originally present in the rocks was converted to nonexpandable clay minerals during metamorphism. Induration of bedrock and loss of expandable clays resulted in thin soils and steep topography

  7. Evaluating relative sensitivity of SWAT-simulated nitrogen discharge to projected climate and land cover changes for two watersheds in North Carolina, USA

    EPA Science Inventory

    We investigated how projected changes in land cover and climate affected simulated nitrate (NO3−) and organic nitrogen (ORGN) discharge for two watersheds within the Neuse River Basin North Carolina, USA for years 2010 to 2070. We applied the Soil and Water Assessment Tool ...

  8. ACIDIFICATION TRENDS AND THE EVOLUTION OF NEUTRALIZATION MECHANISMS THROUGH TIME AT THE BEAR BROOK WATERSHED IN MAINE (BBWM), U.S.A.

    EPA Science Inventory

    The paired catchment study at the forested Bear Brook Watershed in Maine (BBWM) U.S.A. documents interactions among short- to long-term processes of acidification. In 1987-1989, runoff from the two catchments was nearly identical in quality and quantity. Ammonium sulfate has been...

  9. Assessing development pressure in the Chesapeake Bay watershed: An evaluation of two land-use change models

    USGS Publications Warehouse

    Claggett, P.R.; Jantz, C.A.; Goetz, S.J.; Bisland, C.

    2004-01-01

    Natural resource lands in the Chesapeake Bay watershed are increasingly susceptible to conversion into developed land uses, particularly as the demand for residential development grows. We assessed development pressure in the Baltimore-Washington, DC region, one of the major urban and suburban centers in the watershed. We explored the utility of two modeling approaches for forecasting future development trends and patterns by comparing results from a cellular automata model, SLEUTH (slope, land use, excluded land, urban extent, transportation), and a supply/demand/allocation model, the Western Futures Model. SLEUTH can be classified as a land-cover change model and produces projections on the basis of historic trends of changes in the extent and patterns of developed land and future land protection scenarios. The Western Futures Model derives forecasts from historic trends in housing units, a U.S. Census variable, and exogenously supplied future population projections. Each approach has strengths and weaknesses, and combining the two has advantages and limitations. ?? 2004 Kluwer Academic Publishers.

  10. Geomorphic controls on mercury accumulation in soils from a historically mined watershed, Central California Coast Range, USA

    USGS Publications Warehouse

    Holloway, J.M.; Goldhaber, M.B.; Morrison, J.M.

    2009-01-01

    Historic Hg mining in the Cache Creek watershed in the Central California Coast Range has contributed to the downstream transport of Hg to the San Francisco Bay-Delta. Different aspects of Hg mobilization in soils, including pedogenesis, fluvial redistribution of sediment, volatilization and eolian transport were considered. The greatest soil concentrations (>30 mg Hg kg-1) in Cache Creek are associated with mineralized serpentinite, the host rock for Hg deposits. Upland soils with non-mineralized serpentine and sedimentary parent material also had elevated concentrations (0.9-3.7 mg Hg kg-1) relative to the average concentration in the region and throughout the conterminous United States (0.06 mg kg-1). Erosion of soil and destabilized rock and mobilization of tailings and calcines into surrounding streams have contributed to Hg-rich alluvial soil forming in wetlands and floodplains. The concentration of Hg in floodplain sediment shows sediment dispersion from low-order catchments (5.6-9.6 mg Hg kg-1 in Sulphur Creek; 0.5-61 mg Hg kg-1 in Davis Creek) to Cache Creek (0.1-0.4 mg Hg kg-1). These sediments, deposited onto the floodplain during high-flow storm events, yield elevated Hg concentrations (0.2-55 mg Hg kg-1) in alluvial soils in upland watersheds. Alluvial soils within the Cache Creek watershed accumulate Hg from upstream mining areas, with concentrations between 0.06 and 0.22 mg Hg kg-1 measured in soils ~90 km downstream from Hg mining areas. Alluvial soils have accumulated Hg released through historic mining activities, remobilizing this Hg to streams as the soils erode.

  11. The Neoglacial landscape and human history of Glacier Bay, Glacier Bay National Park and Preserve, southeast Alaska, USA

    USGS Publications Warehouse

    Connor, C.; Streveler, G.; Post, A.; Monteith, D.; Howell, W.

    2009-01-01

    The Neoglacial landscape of the Huna Tlingit homeland in Glacier Bay is recreated through new interpretations of the lower Bay's fjordal geomorphology, late Quaternary geology and its ethnographic landscape. Geological interpretation is enhanced by 38 radiocarbon dates compiled from published and unpublished sources, as well as 15 newly dated samples. Neoglacial changes in ice positions, outwash and lake extents are reconstructed for c. 5500?????"200 cal. yr ago, and portrayed as a set of three landscapes at 1600?????"1000, 500?????"300 and 300?????"200 cal. yr ago. This history reveals episodic ice advance towards the Bay mouth, transforming it from a fjordal seascape into a terrestrial environment dominated by glacier outwash sediments and ice-marginal lake features. This extensive outwash plain was building in lower Glacier Bay by at least 1600 cal. yr ago, and had filled the lower bay by 500 cal. yr ago. The geologic landscape evokes the human-described landscape found in the ethnographic literature. Neoglacial climate and landscape dynamism created difficult but endurable environmental conditions for the Huna Tlingit people living there. Choosing to cope with environmental hardship was perhaps preferable to the more severely deteriorating conditions outside of the Bay as well as conflicts with competing groups. The central portion of the outwash plain persisted until it was overridden by ice moving into Icy Strait between AD 1724?????"1794. This final ice advance was very abrupt after a prolonged still-stand, evicting the Huna Tlingit from their Glacier Bay homeland. ?? 2009 SAGE Publications.

  12. Automated feature extraction and spatial organization of seafloor pockmarks, Belfast Bay, Maine, USA

    USGS Publications Warehouse

    Andrews, B.D.; Brothers, L.L.; Barnhardt, W.A.

    2010-01-01

    Seafloor pockmarks occur worldwide and may represent millions of m3 of continental shelf erosion, but few numerical analyses of their morphology and spatial distribution of pockmarks exist. We introduce a quantitative definition of pockmark morphology and, based on this definition, propose a three-step geomorphometric method to identify and extract pockmarks from high-resolution swath bathymetry. We apply this GIS-implemented approach to 25km2 of bathymetry collected in the Belfast Bay, Maine USA pockmark field. Our model extracted 1767 pockmarks and found a linear pockmark depth-to-diameter ratio for pockmarks field-wide. Mean pockmark depth is 7.6m and mean diameter is 84.8m. Pockmark distribution is non-random, and nearly half of the field's pockmarks occur in chains. The most prominent chains are oriented semi-normal to the steepest gradient in Holocene sediment thickness. A descriptive model yields field-wide spatial statistics indicating that pockmarks are distributed in non-random clusters. Results enable quantitative comparison of pockmarks in fields worldwide as well as similar concave features, such as impact craters, dolines, or salt pools. ?? 2010.

  13. Delineation of capture zones for municipal wells in fractured dolomite, Sturgeon Bay, Wisconsin, USA

    NASA Astrophysics Data System (ADS)

    Rayne, Todd W.; Bradbury, Kenneth R.; Muldoon, Maureen A.

    2001-10-01

    A wellhead protection study for the city of Sturgeon Bay, Wisconsin, USA, demonstrates the necessity of combining detailed hydrostratigraphic analysis with groundwater modeling to delineate zones of contribution for municipal wells in a fractured dolomite aquifer. A numerical model (MODFLOW) was combined with a particle tracking code (MODPATH) to simulate the regional groundwater system and to delineate capture zones for municipal wells. The hydrostratigraphic model included vertical and horizontal fractures and high-permeability zones. Correlating stratigraphic interpretations with field data such as geophysical logs, packer tests, and fracture mapping resulted in the construction of a numerical model with five high-permeability zones related to bedding planes or facies changes. These zones serve as major conduits for horizontal groundwater flow. Dipping fracture zones were simulated as thin high-permeability layers. The locations of exposed bedrock and surficial karst features were used to identify areas of enhanced recharge. Model results show the vulnerability of the municipal wells to pollution. Capture zones for the wells extend several kilometers north and south from the city. Travel times from recharge areas to all wells were generally less than one year. The high seasonal variability of recharge in the study area made the use of a transient model necessary.

  14. Seasonal hematology and serum chemistry of wild beluga whales (Delphinapterus leucas) in Bristol Bay, Alaska, USA.

    PubMed

    Norman, Stephanie A; Goertz, Caroline E C; Burek, Kathy A; Quakenbush, Lori T; Cornick, Leslie A; Romano, Tracy A; Spoon, Tracey; Miller, Woutrina; Beckett, Laurel A; Hobbs, Roderick C

    2012-01-01

    We collected blood from 18 beluga whales (Delphinapterus leucas), live-captured in Bristol Bay, Alaska, USA, in May and September 2008, to establish baseline hematologic and serum chemistry values and to determine whether there were significant differences in hematologic values by sex, season, size/age, or time during the capture period. Whole blood was collected within an average of 19 min (range=11-30 min) after the net was set for capture, and for eight animals, blood collection was repeated in a later season after between 80-100 min; all blood was processed within 12 hr. Mean hematocrit, chloride, creatinine, total protein, albumin, and alkaline phosphatase were significantly lower in May than they were in September, whereas mean corpuscular hemoglobin concentration, monocytes, phosphorous, magnesium, blood urea nitrogen, alanine aminotransferase, aspartate aminotransferase, γ-glutamyltranspeptidase, and creatinine kinase were significantly higher. Mean total protein, white blood cell count, neutrophils, and lymphocytes were significantly higher early in the capture period than they were later. No significant differences in blood analyte values were noted between males and females. Using overall body length as a proxy for age, larger (older) belugas had lower white blood cell, lymphocyte, and eosinophil counts as well as lower sodium, potassium, and calcium levels but higher creatinine levels than smaller belugas. These data provide values for hematology and serum chemistry for comparisons with other wild belugas.

  15. Anatomy of the Chesapeake Bay impact structure revealed by seismic imaging, Delmarva Peninsula, Virginia, USA

    USGS Publications Warehouse

    Catchings, R.D.; Powars, D.S.; Gohn, G.S.; Horton, J.W.; Goldman, M.R.; Hole, J.A.

    2008-01-01

    A 30-km-long, radial seismic reflection and refraction survey completed across the northern part of the late Eocene Chesapeake Bay impact structure (CBIS) on the Delmarva Peninsula, Virginia, USA, confirms that the CBIS is a complex central-peak crater. We used a tomographic P wave velocity model and low-fold reflection images, constrained by data from two deep boreholes located on the profile, to interpret the structure and composition of the upper 5 km of crust. The seismic images exhibit well-defined structural features, including (with increasing radial distance) a collapsed central uplift, a breccia-filled moat, and a collapsed transient-crater margin (which collectively constitute a ???40-km-wide collapsed transient crater), and a shallowly deformed annular trough. These seismic images are the first to resolve the deep structure of the crater (>1 km) and the boundaries between the central uplift, moat, and annular trough. Several distinct seismic signatures distinguish breccia units from each other and from more coherent crystalline rocks below the central uplift, moat, and annular trough. Within the moat, breccia extends to a minimum depth of 1.5 km or a maximum of 3.5 km, depending upon the interpretation of the deepest layered materials. The images show ???350 to 500 m of postimpact sediments above the impactites. The imaged structure of the CBIS indicates a complex sequence of event during the cratering process that will provide new constraints for numerical modeling. Copyright 2008 by the American Geophysical Union.

  16. Depositional history of organic contaminants in Narragansett Bay, Rhode Island, USA.

    PubMed

    Hartmann, Paul C; Quinn, James G; Cairns, Robert W; King, John W

    2005-04-01

    Sediment cores were taken at three locations in Narragansett Bay, Rhode Island, USA in 1997 and analyzed for a variety of organic contaminants including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), chlordanes, linear alkyl benzenes (LABs), benzotriazoles (BZTs) and dichlorodiphenyltrichloroethanes (DDTs) and metabolites. The distributions of these chemicals at Apponaug Cove and in the Seekonk River indicate that there was a disturbance in the depositional environment relative to cores collected at these locations in 1986 demonstrating the potential for buried contaminants to be remobilized in the environment even after a period of burial. Sharp breaks in the concentration of several organic markers with known dates of introduction were successfully used to determine the sedimentation rate at Quonset Point. Both the Quonset Point and Seekonk River cores had subsurface maximums for DDTs, PCBs, PAHs and BZTs, which are consistent with expected inputs to the environment. The Apponaug Cove core showed an increase of most contaminants at the surface indicating a recent event in which more contaminated sediments were deposited at that location.

  17. Investigating the Sources and Dynamics of Dissolved Organic Matter in an Agricultural Watershed in California (U.S.A.)

    NASA Astrophysics Data System (ADS)

    Dyda, R. Y.; Hernes, P. J.; Spencer, R. G.; Ingrum, T. D.; Pellerin, B. A.; Bergamaschi, B. A.

    2007-12-01

    Dissolved organic matter (DOM) is ubiquitous and plays critical roles in nutrient cycling, aquatic food webs and numerous other biogeochemical processes. Furthermore, various factors control the quality and quantity of DOM, including land use, soil composition, in situ production, microbial uptake and assimilation and hydrology. As a component of DOM, dissolved organic carbon (DOC) has been recently identified as a drinking water constituent of concern due to its propensity to form EPA-regulated carcinogenic compounds when disinfected for drinking water purposes. Therefore, understanding the sources, cycling and modification of DOC across various landscapes is of direct relevance to a wide range of studies. The Willow Slough watershed is located in the Central Valley of California (U.S.A.) and is characterized by both diverse geomorphology as well as land use. The watershed drains approximately 425 km2 and is bordered by Cache and Putah Creeks to the north and south. The study area in the watershed includes the eastern portion of the foothills of the inner Coast Range and the alluvial plain and encompasses diverse land uses, including orchards, viticulture, dairy, pasture and natural grasslands. The Willow Slough watershed represents a unique opportunity to examine DOC dynamics through multiple land uses and hydrologic flow paths that are common throughout California. Preliminary data show that DOC concentrations at the watershed mouth peak during winter storms and also increase gradually throughout the summer months during the agricultural irrigation season. The increasing DOC concentrations during the summer months may result from agricultural runoff and/or primary production in channel. In addition, initial results using the chromophoric DOM (CDOM) absorption coefficient and spectral slope parameters indicate seasonal differences in the composition of the DOM. Spectral slopes decreased during both the summer irrigation season and winter storms relative to winter

  18. Bed coarsening, riffle shortening, and channel enlargement in urbanizing watersheds, northern Kentucky, USA

    NASA Astrophysics Data System (ADS)

    Hawley, Robert J.; MacMannis, Katherine R.; Wooten, Matthew S.

    2013-11-01

    Stream systems naturally respond to watershed land use dynamics, particularly in urban developments with unmanaged impervious areas. Such urban-provoked alterations to channel morphology cause water quality impairments, have adverse effects on aquatic biota, and pose risks to adjacent public infrastructure. Over the past four years we have collected detailed hydrogeomorphic data at 40 unique stream locations throughout northern Kentucky, with at least two rounds of annually repeated surveys at 70% of the sites and three rounds of surveys at 50% of the sites. Analysis of this time-series data encompassed measured rates of instability across three distinct dimensions including (1) channel cross sections, (2) longitudinal profiles, and (3) bed material particle composition. Regression analyses between geomorphic change and 2011 watershed imperviousness indicated stream cross sections in urban/suburban watersheds tend to be getting larger-their overall shape is both deepening and widening. Additionally, stream riffle lengths are shrinking and their pools are becoming both longer and deeper; and finally, their bed material composition is coarsening, particularly in streams in the early stages of watershed development. By documenting fluvial geomorphologic dynamics in such detail, this study highlights the process by which unmitigated urbanization homogenizes stream habitat and degrades aquatic ecosystems. This improved, process-based understanding of the urban-induced channel response sequence has clear implications to both stormwater management and stream/ecosystem restoration, particularly in stream systems where headcut migration is a primary driver of channel instability.

  19. Effects of geomorphology, habitat, and spatial location on fish assemblages in a watershed in Ohio, USA.

    PubMed

    D'Ambrosio, Jessica L; Williams, Lance R; Witter, Jonathan D; Ward, Andy

    2009-01-01

    In this paper, we evaluate relationships between in-stream habitat, water chemistry, spatial distribution within a predominantly agricultural Midwestern watershed and geomorphic features and fish assemblage attributes and abundances. Our specific objectives were to: (1) identify and quantify key environmental variables at reach and system wide (watershed) scales; and (2) evaluate the relative influence of those environmental factors in structuring and explaining fish assemblage attributes at reach scales to help prioritize stream monitoring efforts and better incorporate all factors that influence aquatic biology in watershed management programs. The original combined data set consisted of 31 variables measured at 32 sites, which was reduced to 9 variables through correlation and linear regression analysis: stream order, percent wooded riparian zone, drainage area, in-stream cover quality, substrate quality, gradient, cross-sectional area, width of the flood prone area, and average substrate size. Canonical correspondence analysis (CCA) and variance partitioning were used to relate environmental variables to fish species abundance and assemblage attributes. Fish assemblages and abundances were explained best by stream size, gradient, substrate size and quality, and percent wooded riparian zone. Further data are needed to investigate why water chemistry variables had insignificant relationships with IBI scores. Results suggest that more quantifiable variables and consideration of spatial location of a stream reach within a watershed system should be standard data incorporated into stream monitoring programs to identify impairments that, while biologically limiting, are not fully captured or elucidated using current bioassessment methods.

  20. Water Quality Monitoring and Assessment in Northern New Jersey Watershed, USA

    NASA Astrophysics Data System (ADS)

    Feng, H.; Mirrer, L. K.; Pelak, N. F.; Wu, M. S.

    2012-12-01

    Over a century of rapid urbanization and industrialization in New Jersey brought visible ever-increasing stress on the resource and environmental capacities of the watershed. Environmental quality is a major concern in this region with the urbanization and economic development. As a 8-week long National Science Foundation (NSF)-supported Research Experience for Undergraduate Students (REU) program, this study compares the stream water quality in four Northern New Jersey watersheds with different land use types (i.e., urban, agricultural, and forested). A total of eight sites were chosen for this study with two sites for each watershed to investigate if the land use type has an effect on the water quality, and if so, what that effect is. Physical and chemical parameters, such as temperature, pH, conductivity, solids content, nitrate, and phosphate, were measured during this study as indicators of the water quality. A number of correlations between these parameters were found during the data analysis. Our preliminary results indicate that the land use change has a significant impact on the water quality, causing impaired rivers, streams, lakes and reservoirs in New Jersey watershed. The results from this study are important and useful for developing future environmental management strategies for environmental restoration and urban coastal development. Acknowledgement: The research was supported in part by the US National Science Foundation (Award EAR-1004829).

  1. IMPACTS OF MARINE AEROSOLS ON SURFACE WATER CHEMISTRY AT BEAR BROOK WATERSHED, MAINE USA

    EPA Science Inventory

    The East Bear catchment at Bear Brook Watershed, Maine receives moderate (for the eastern U.S.) amounts of Cl- in wet and dry deposition. In 1989, Cl- in precipitation ranged from 2 to 55 eq/L. Dry, occult, and wet deposition plus evapotranspiration resulted in stream Cl- averagi...

  2. APPARENT 85KRYPTON AGES OF GROUNDWATER WITHIN THE ROYAL WATERSHED, MAINE, USA

    EPA Science Inventory

    85Kr activities were determined in 264 domestic and municipal wells from 2002-2004 in the Royal watershed (361 km2), Maine. Gas extraction for 85Kr from wells was effected directly via a well-head methodology permitting efficient widespread analys...

  3. USDA-ARS Riesel Watersheds, Riesel, Texas, USA: Water quality research database

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The 75 year legacy database including discharge, sediment loss, land management, and meteorological data for the USDA-ARS Riesel Watersheds has been available on the web for more than a decade (www.ars.usda.gov/spa/hydro-data); however, only recently have additional water quality data been added. T...

  4. A Preliminary Watershed Scale Soil Quality Assessment in North Central Iowa USA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil quality assessment has been recognized as an important step toward understanding the long-term effects of tillage, cropping system, landscape position, and conservation practices within agricultural watersheds. Our objective is to provide an initial assessment of various soil quality indicators...

  5. Assessing pesticide wet deposition risk within a small agricultural watershed in the Southeastern Coastal Plain (USA)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pesticide volatilization and deposition with precipitation is widely documented and has been connected to adverse ecological impact. Here we describe a 3-yr study of current use and legacy pesticides in event-based rain samples within a 123-ha agricultural watershed. Crops in farm fields were docum...

  6. Ecosystem Services Approaches to Restoring a Sustainable Chesapeake Bay and its Tributary Watersheds

    EPA Science Inventory

    Within this set of reports and papers, the authors developed an optimization framework to examine how incorporating selected co-benefits (carbon sequestration, recreation/hunting, air quality) of nutrient reductions alters their optimal distribution in the watershed. They used th...

  7. Linking Ecosystem Services Supply to Stakeholder Values in Guanica Bay Watershed, Puerto Rico

    EPA Science Inventory

    Policies to protect coastal resources will be more effective when they account for the social and economic concerns of stakeholders in the coastal zone and watershed, and are responsive to potential tradeoffs between benefits offered by both land and sea. We focus on the Gu&aacu...

  8. Managing Saginaw Bay nutrient loading by surrounding watersheds through near real time hydrologic resource sheds

    EPA Science Inventory

    We can quantify source areas contributing material to a location during various time periods as resource sheds. Various kinds of resource sheds and their source material distributions are defined. For watershed hydrology, we compute resource sheds and their source material distri...

  9. Spatial Statistical Network Models for Stream and River Temperature in the Chesapeake Bay Watershed, USA

    EPA Science Inventory

    Regional temperature models are needed for characterizing and mapping stream thermal regimes, establishing reference conditions, predicting future impacts and identifying critical thermal refugia. Spatial statistical models have been developed to improve regression modeling techn...

  10. Cytochrome P450 and organochlorine contaminants in black-crowned night-herons from the Chesapeake Bay region, USA

    SciTech Connect

    Rattner, B.A.; Melancon, M.J.; Rice, C.P.; Riley, W. Jr.; Eisemann, J.; Hines, R.K.

    1997-11-01

    Black-crowned night-heron offspring were collected from a relatively uncontaminated coastal reference site and two sites in the Chesapeake Bay watershed. Hepatic microsomal activities of benzyloxyresorufin-O-dealkylase and ethoxyresorufin-O-dealkylase were elevated in pipping embryos from the Baltimore Harbor colony compared to the reference site, whereas values in embryos from the Rock Creek Park colony were intermediate. Concentrations of organochlorine pesticides and metabolites in pipping embryos from both sites in the Chesapeake watershed were greater than at the reference site but below the known threshold for reproductive impairment. However, concentrations of 10 arylhydrocarbon receptor-active polychlorinated biphenyl (PCB) congeners and estimated toxic equivalents were up to 37-fold greater in embryos collected from these two sites in the Chesapeake Bay region, with values for toxic congeners 77 and 126 exceeding those observed in pipping heron embryos from the Great Lakes. Monooxygenase activity of pipping embryos was associated with concentrations of several organochlorine pesticides, total PCBs, arylhydrocarbon receptor-active PCB congeners, and toxic equivalents, providing further evidence of the value of cytochrome P450 as a biomarker of organic contaminant exposure. Organochlorine contaminant levels were greater in 10-d-old nestlings from Baltimore Harbor than the reference site but had no apparent effect on monooxygenase activity or growth. These findings demonstrate induction of cytochrome P450 in pipping black-crowned night-heron embryos in the Chesapeake Bay region, probably by exposure to PCB congeners of local origin, and the accumulation of organochlorine pesticides and metabolites in nestling herons from Baltimore Harbor. Biomonitoring and additional waterbird species that appear to be more sensitive to PCBs than black-crowned night-herons is recommended to document health of waterbirds and remediation of the Chesapeake Bay.

  11. Analysis of survey data on the chemistry of twenty-three streams in the Chesapeake Bay watershed: some implications of the impact of acid deposition. Final report

    SciTech Connect

    Janicki, A.; Cummins, R.

    1983-12-01

    A survey of the chemistry of 23 streams within the Chesapeake Bay watershed was conducted in the spring of 1983 to determine whether a potential for changes in water chemistry due to atmospheric inputs of acidic materials exists in any of these streams. Sampling was conducted weekly through the months of March and April. Three streams were identified as being likely affected by acid inputs due to relatively high H(+) and SO4(-2) concentrations and low alkalinities: Stockett's Run, Lyons Creek, and Muddy Creek. Elevated dissolved aluminum concentrations were observed in some Eastern Shore streams and are likely related to the predominance of clay soils in their watersheds.

  12. Gulf of Mexico Integrated Science - Tampa Bay Study: Watershed and Estuary Mapping

    USGS Publications Warehouse

    Hansen, Mark

    2005-01-01

    Tampa Bay, Florida, and its environs have experienced phenomenal urban growth and significant changes in land-use practices over the past 50 years. This trend is expected to continue, with human activity intensifying and affecting a wider geographic region. Urbanization creates impervious surfaces, which increase stormwater runoff and contribute to greater amounts of chemicals flowing into coastal waters. Man-made structures including bridges, a gas pipeline, desalination plant, ports, navigation channels, and extensive sea walls have been built and will continue to be maintained and modified. This task of the Tampa Bay Study aims to provide a better understanding of these and other man-made impacts on the Tampa Bay region.

  13. Groundwater flow and its effect on salt dissolution in Gypsum Canyon watershed, Paradox Basin, southeast Utah, USA

    NASA Astrophysics Data System (ADS)

    Reitman, Nadine G.; Ge, Shemin; Mueller, Karl

    2014-09-01

    Groundwater flow is an important control on subsurface evaporite (salt) dissolution. Salt dissolution can drive faulting and associated subsidence on the land surface and increase salinity in groundwater. This study aims to understand the groundwater flow system of Gypsum Canyon watershed in the Paradox Basin, Utah, USA, and whether or not groundwater-driven dissolution affects surface deformation. The work characterizes the groundwater flow and solute transport systems of the watershed using a three-dimensional (3D) finite element flow and transport model, SUTRA. Spring samples were analyzed for stable isotopes of water and total dissolved solids. Spring water and hydraulic conductivity data provide constraints for model parameters. Model results indicate that regional groundwater flow is to the northwest towards the Colorado River, and shallow flow systems are influenced by topography. The low permeability obtained from laboratory tests is inconsistent with field observed discharges, supporting the notion that fracture permeability plays a significant role in controlling groundwater flow. Model output implies that groundwater-driven dissolution is small on average, and cannot account for volume changes in the evaporite deposits that could cause surface deformation, but it is speculated that dissolution may be highly localized and/or weaken evaporite deposits, and could lead to surface deformation over time.

  14. Effects of contaminant exposure on reproductive success of ospreys (Pandion haliaetus) nesting in Delaware River and Bay, USA

    USGS Publications Warehouse

    Toschik, P.C.; Rattner, B.A.; McGowan, P.C.; Christman, M.C.; Carter, Daniel B.; Hale, R.C.; Matson, C.W.; Ottinger, M.A.

    2005-01-01

    Despite serious water-quality problems and pollutant loading and retention, Delaware River and Bay (USA) provide important wildlife habitat. In 2002, we conducted a comprehensive evaluation of contaminant exposure and reproduction of ospreys (Pandion haliaetus) breeding in Delaware River and Bay. Sample eggs were collected from 39 nests and analyzed for organochlorine pesticides, polychlorinated biphenyls (PCBs), and mercury; a subset of 15 eggs was analyzed for perfluorinated compounds and polybrominated diphenyl ethers (PBDEs). The fate of each nest was monitored weekly. Concentrations of 10 organochlorine pesticides or metabolites, total PCBs, and several toxic PCB congeners were greater (p < 0.05) in eggs collected between the Chesapeake and Delaware Canal (C and D Canal) and Trenton (Delaware River and northern Bay) compared to other sites. Concentrations of p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE; 0.785-3.84 mug/g wet wt) and total PCBs (5.50-14.5 mug/g wet wt) in eggs collected between the C and D Canal and Trenton were similar to levels recently found in the Chesapeake Bay. In all study segments, at least one young fledged from 66 to 75% of nests. Productivity for Delaware Inland Bays (reference area) and southern Delaware Bay was 1.17 and 1.42 fledglings/active nest, respectively; north of the C and D Canal, productivity was 1.00 fledgling/active nest, which is marginally adequate to maintain the population. Using these data, a logistic regression model found that contaminant concentrations (p,p'-DDE, heptachlor epoxide, chlordane and metabolites, and total PCBs) were predictive of hatching success. Several perfluorinated compounds and PBDEs were detected in eggs at concentrations approaching 1 mug/g wet weight. These findings provide evidence that contaminants continue to be a significant stressor on osprey productivity in the northern Delaware River and Bay.

  15. Contrasting residence times and fluxes of water and sulfate in two small forested watersheds in Virginia, USA

    USGS Publications Warehouse

    Böhlke, J.K.; Michel, R.L.

    2009-01-01

    Watershed mass balances for solutes of atmospheric origin may be complicated by the residence times of water and solutes at various time scales. In two small forested headwater catchments in the Appalachian Mountains of Virginia, USA, mean annual export rates of SO4= differ by a factor of 2, and seasonal variations in SO4= concentrations in atmospheric deposition and stream water are out of phase. These features were investigated by comparing 3H, 35S, ??34S, ??2H, ??18O, ??3He, CFC-12, SF6, and chemical analyses of open deposition, throughfall, stream water, and spring water. The concentrations of SO4= and radioactive 35S were about twice as high in throughfall as in open deposition, but the weighted composite values of 35S/S (11.1 and 12.1 ?? 10- 15) and ??34S (+ 3.8 and + 4.1???) were similar. In both streams (Shelter Run, Mill Run), 3H concentrations and ??34S values during high flow were similar to those of modern deposition, ??2H and ??18O values exhibited damped seasonal variations, and 35S/S ratios (0-3 ?? 10- 15) were low throughout the year, indicating inter-seasonal to inter-annual storage and release of atmospheric SO4= in both watersheds. In the Mill Run watershed, 3H concentrations in stream base flow (10-13??TU) were consistent with relatively young groundwater discharge, most ??34S values were approximately the same as the modern atmospheric deposition values, and the annual export rate of SO4= was equal to or slightly greater than the modern deposition rate. In the Shelter Run watershed, 3H concentrations in stream base flow (1-3??TU) indicate that much of the discharging ground water had been deposited prior to the onset of atmospheric nuclear bomb testing in the 1950s, base flow ??34S values (+ 1.6???) were significantly lower than the modern deposition values, and the annual export rate of SO4= was less than the modern deposition rate. Concentrations of 3H and 35S in Shelter Run base flow, and of 3H, 3He, CFC-12, SF6, and 35S in a spring

  16. Contrasting residence times and fluxes of water and sulfate in two small forested watersheds in Virginia, USA.

    PubMed

    Böhlke, John Karl; Michel, Robert L

    2009-07-01

    Watershed mass balances for solutes of atmospheric origin may be complicated by the residence times of water and solutes at various time scales. In two small forested headwater catchments in the Appalachian Mountains of Virginia, USA, mean annual export rates of SO(4)(=) differ by a factor of 2, and seasonal variations in SO(4)(=) concentrations in atmospheric deposition and stream water are out of phase. These features were investigated by comparing (3)H, (35)S, delta(34)S, delta(2)H, delta(18)O, delta(3)He, CFC-12, SF(6), and chemical analyses of open deposition, throughfall, stream water, and spring water. The concentrations of SO(4)(=) and radioactive (35)S were about twice as high in throughfall as in open deposition, but the weighted composite values of (35)S/S (11.1 and 12.1x10(-15)) and delta(34)S (+3.8 and +4.1 per thousand) were similar. In both streams (Shelter Run, Mill Run), (3)H concentrations and delta(34)S values during high flow were similar to those of modern deposition, delta(2)H and delta(18)O values exhibited damped seasonal variations, and (35)S/S ratios (0-3x10(-15)) were low throughout the year, indicating inter-seasonal to inter-annual storage and release of atmospheric SO(4)(=) in both watersheds. In the Mill Run watershed, (3)H concentrations in stream base flow (10-13 TU) were consistent with relatively young groundwater discharge, most delta(34)S values were approximately the same as the modern atmospheric deposition values, and the annual export rate of SO(4)(=) was equal to or slightly greater than the modern deposition rate. In the Shelter Run watershed, (3)H concentrations in stream base flow (1-3 TU) indicate that much of the discharging ground water had been deposited prior to the onset of atmospheric nuclear bomb testing in the 1950s, base flow delta(34)S values (+1.6 per thousand) were significantly lower than the modern deposition values, and the annual export rate of SO(4)(=) was less than the modern deposition rate

  17. EPA Interim Evaluation of 2012-2013 Milestone Progress in the Chesapeake Bay Watershed

    EPA Pesticide Factsheets

    This page provides the EPA interim evaluations of the 2012-2013 milestones for the Chesapeake Bay TMDL. These interim assessments provide a mid-point check on the progress made on the 2012-2013 milestones, recognizing the achievements made in 2012.

  18. EPA Interim Evaluation of 2014-2015 Milestone Progress in the Chesapeake Bay Watershed

    EPA Pesticide Factsheets

    This page provides the EPA interim evaluations of the 2014-2015 milestones for the Chesapeake Bay TMDL. These interim assessments provide a mid-point check on the progress made on the 2014-2015 milestones, recognizing the achievements made in 2014.

  19. Trend analysis of stressors and ecological responses, particularly nutrients, in the Narragansett Bay Watershed.

    EPA Science Inventory

    Current and historic impacts of nitrogen on water quality were evaluated and relationships between nutrients and ecosystem structure and function were developed for Narragansett Bay, RI. Land use land cover change analysis from 1985 thru 2005 resulted in a 7% increase in urban la...

  20. Mercury Transport During Snowmelt in Three Mountain Watersheds in Northern Utah, USA

    NASA Astrophysics Data System (ADS)

    Packer, B. N.; Carling, G. T.; Tingey, D. G.

    2015-12-01

    Mercury (Hg) transport during snowmelt is widely recognized as a significant source of Hg to high elevation lakes and streams. However, it is not well understood to what extent Hg is associated with suspended sediment versus dissolved organic matter during snowmelt runoff. To investigate Hg transport during snowmelt, we collected samples for filtered and unfiltered total Hg (THg) and dissolved organic carbon (DOC) in snowpack and snowmelt runoff across three snow-dominated watersheds in northern Utah: Logan River, Provo River, and Little Cottonwood Creek. The watersheds were selected to cover a range of geologic and hydrologic conditions typical of the Rocky Mountain region. Initial results show that snowpack THg concentrations were similar across the watersheds (0.87 - 1.69 ng/L) but river THg concentrations were highly variable. The Provo River showed the highest THg concentrations approaching 6 ng/L during peak flows, whereas maximum THg concentrations in the Logan River were <2 ng/L. Little Cottonwood Creek showed intermediate THg concentrations. THg and DOC showed strong positive correlation in the Provo River (R2=0.68) but were not correlated in the Logan River (R2=0.04). Notably, the Provo River showed the highest fraction of "dissolved" THg (calculated as the fraction of filtered/unfiltered concentration) averaging 75% compared with the other sites where the "dissolved" fraction was <45%. These results suggest that the majority of THg is transported in association with DOC in the Provo River but is more strongly associated with suspended sediments in the Logan River and Little Cottonwood Creek. These findings have implications for understanding Hg cycling in the Provo River watershed where Jordanelle Reservoir has fish consumption advisories due elevated Hg concentrations. The dissolved load of THg, possibly associated with DOC, is likely methylated in Jordanelle Reservoir where it bio-accumulates up the food web.

  1. Integrating sentinel watershed-systems into the monitoring and assessment of Minnesota's (USA) waters quality.

    PubMed

    Magner, J A; Brooks, K N

    2008-03-01

    Section 303(d) of the Clean Water Act requires States and Tribes to list waters not meeting water quality standards. A total maximum daily load must be prepared for waters identified as impaired with respect to water quality standards. Historically, the management of pollution in Minnesota has been focused on point-source regulation. Regulatory effort in Minnesota has improved water quality over the last three decades. Non-point source pollution has become the largest driver of conventional 303(d) listings in the 21st century. Conventional pollutants, i.e., organic, sediment and nutrient imbalances can be identified with poor land use management practices. However, the cause and effect relationship can be elusive because of natural watershed-system influences that vary with scale. Elucidation is complex because the current water quality standards in Minnesota were designed to work best with water quality permits to control point sources of pollution. This paper presents a sentinel watershed-systems approach (SWSA) to the monitoring and assessment of Minnesota waterbodies. SWSA integrates physical, chemical, and biological data over space and time using advanced technologies at selected small watersheds across Minnesota to potentially improve understanding of natural and anthropogenic watershed processes and the management of point and non-point sources of pollution. Long-term, state-of-the-art monitoring and assessment is needed to advance and improve water quality standards. Advanced water quality or ecologically-based standards that integrate physical, chemical, and biological numeric criteria offer the potential to better understand, manage, protect, and restore Minnesota's waterbodies.

  2. Validation of MODIS FLH and In Situ Chlorophyll a from Tampa Bay, Florida (USA)

    NASA Technical Reports Server (NTRS)

    Fischer, Andrew; MorenoMadrinan, Max J.

    2012-01-01

    Satellite observation of phytoplankton concentration or chlorophyll-a (chla) is an important characteristic, critically integral to monitoring coastal water quality. However, the optical properties of estuarine and coastal waters are highly variable and complex and pose a great challenge for accurate analysis. Constituents such as suspended solids and dissolved organic matter and the overlapping and uncorrelated absorptions in the blue region of the spectrum renders the blue-green ratio algorithms for estimating chl-a inaccurate. Measurement of suninduced chlorophyll fluorescence, on the other hand, which utilizes the near infrared portion of the electromagnetic spectrum may, provide a better estimate of phytoplankton concentrations. While modelling and laboratory studies have illustrated both the utility and limitations of satellite algorithms based on the sun induced chlorophyll fluorescence signal, few have examined the empirical validity of these algorithms or compared their accuracy against bluegreen ratio algorithms . In an unprecedented analysis using a long term (2003-2011) in situ monitoring data set from Tampa Bay, Florida (USA), we assess the validity of the FLH product from the Moderate Resolution Imaging Spectrometer against a suite of water quality parameters taken in a variety of conditions throughout this large optically complex estuarine system. . Overall, the results show a 106% increase in the validity of chla concentration estimation using FLH over the standard chla estimate from the blue-green OC3M algorithm. Additionally, a systematic analysis of sampling sites throughout the bay is undertaken to understand how the FLH product responds to varying conditions in the estuary and correlations are conducted to see how the relationships between satellite FLH and in situ chlorophyll-a change with depth, distance from shore, from structures like bridges, and nutrient concentrations and turbidity. Such analysis illustrates that the correlations between

  3. ALAWAT: A spatially allocated watershed model for approximating stream, sediment, and pollutant flows in Hawaii, USA

    NASA Astrophysics Data System (ADS)

    Freeman, William; Fox, Jefferson

    1995-07-01

    The Ala Wai Canal Watershed Model (ALAWAT) is a planning-level watershed model for approximating direct runoff, streamflow, sediment loads, and loads for up to five pollutants. ALAWAT uses raster GIS data layers including land use, SCS soil hydrologic groups, annual rainfall, and subwatershed delineations as direct model parameter inputs and can use daily total rainfall from up to ten rain gauges and streamflow from up to ten stream gauges. ALAWAT uses a daily time step and can simulate flows for up to ten-year periods and for up to 50 subwatersheds. Pollutant loads are approximated using a user-defined combination of rating curve relationships, mean event concentrations, and loading/washoff parameters for specific subwatersheds, land uses, and times of year. Using ALAWAT, annual average streamflow and baseflow relationships and urban suspended sediment loads were approximated for the Ala Wai Canal watershed (about 10,400 acres) on the island of Oahu, Hawaii. Annual average urban suspended sediments were approximated using two methods: mean event concentrations and pollutant loading and washoff. Parameters for the pollutant loading and washoff method were then modified to simulate the effect of various street sweeping intervals on sediment loads.

  4. Geographic distribution of human blastomycosis cases in Milwaukee, Wisconsin, USA: association with urban watersheds.

    PubMed

    Baumgardner, Dennis J; Knavel, Erica M; Steber, Dale; Swain, Geoffrey R

    2006-05-01

    Most studies of endemic blastomycosis and outbreaks have involved rural areas. Case homesites in rural Northern Wisconsin have been associated with waterways and sand soils. ARC-GIS was used to geocode addresses and to observe geographic features of homesites from 45 State-mandated reports of human blastomycosis in urban Milwaukee County, Southeastern Wisconsin 2000-2004. Each case property was directly observed, and houses and duplexes (N = 38) were compared with 151 same-street control homesites. Categorical data was analyzed using a chi-square or Fisher's exact test; continuous variables by Kruskal-Wallis test. One case cluster was seen on Milwaukee's North side where the estimated annual incidence was 2.8/100,000 compared to 0.96/100,000 for the entire county. Cases were less common in the most urbanized watersheds (0.49/100,000/yr) versus Lake Michigan shores (0.85) versus remaining three open watersheds (1.4) [P<0.01]. Case homesites averaged 1067 m to waterways and none were on sand soils. (Comparison is made to a Northern Wisconsin community where case homesites averaged 354 m to waterways, 24/25 were on sand soils and annual incidence was 74/100,000.) No unique features of case homesites were identified in Milwaukee County. In this urban area of Wisconsin, relatively low incidence rates may be explained, in part, by lower density of inland waterways and lack of sand soils, however, blastomycosis cases appear to be associated with open watersheds.

  5. Use of GIS for the evaluation of heavy metal contamination in the Cunha Canal watershed and west of the Guanabara Bay, Rio de Janeiro, RJ.

    PubMed

    Borges, Renata Coura; Caldas, Vanessa Godoy; Filho, Francisco Fernando Lamego Simões; Ferreira, Marcos Manoel; Lapa, Celso Marcelo Franklin

    2014-12-15

    The Cunha Canal watershed, which is located in the municipality of Rio de Janeiro, suffered severe environmental degradation in recent decades due to rapid urban population growth. However, this substantial growth did not result in social development; instead, it exacerbated existing environmental and social problems. This study aimed to evaluate the pollution of the Canal do Cunha and Guanabara Bay, using GIS for mapping based on the result of the heavy metal concentrations obtained by spectrometry (ICP-OES). The analyzed data were monitored at five collection points. Five heavy metals (Cd, Pb, Cu, Ni and Zn) were evaluated. The results showed that the waters of the Cunha Canal watershed and the west side of Guanabara Bay have been altered and degraded. The concentration of heavy metals in the water was lower than the concentration in the sediments. The behaviors of the studied metals differed during the rainy and dry periods.

  6. Changes in Streamflow and Water Quality in Selected Nontidal Basins in the Chesapeake Bay Watershed, 1985-2004

    USGS Publications Warehouse

    Langland, Michael J.; Raffensperger, Jeff P.; Moyer, Douglas; Landwehr, Jurate M.; Schwarz, Gregory E.

    2006-01-01

    As part of an annual evaluation of water-quality conditions by the Chesapeake Bay Program, water-quality and streamflow data from 32 sites in nontidal parts of the Chesapeake Bay watershed were analyzed to document annual nutrient and sediment trends for 1985 through 2004. This study also formalized different trend tests and methodologies used in assessing the effectiveness of man-agement actions in reducing nutrients and sediments to the Chesapeake Bay. Trends in streamflow were tested at multiple time scales (daily, seasonal, and annual), resulting in only one significant trend (annual-mean streamflow for the Choptank River near Greensboro, Md.). Total freshwater flow entering the bay for the July-August-September 'summer' season 2004 was the highest ever estimated for that 3-month period (1937-2004). Observed (unbiased) concentration summaries indi-cate higher ranges in total-nitrogen concentrations in the northern major river basins, those in Pennsylvania, Maryland, and northern Virginia, compared to the more southern basins in Virginia. Almost half of the monitoring sites in the northern basins exhibited significant downward trends in total nitrogen with time. Comparisons with total phosphorus and sediment showed similar results to total nitrogen. Monthly and annual loads were available for the River Input Monitoring Program sites from the U.S. Geological Survey. Although loads were significantly reduced from 2003, in 2004, the combined estimated total nitrogen loads were the third highest since 1990, whereas total phosphorus and sediment loads were the fifth highest. A flow-weighted concentration (FWC) is useful in evaluating changes through time. Combined annual mean total nitrogen FWC from the 9 River Input Monitoring Program sites indicated a downward tendency from 1985 through 1998 and an upward tendency since 2001. From 1990 to 2004, the mean concentrations of total nitrogen, total phosphorus, and sediment were 1.58, 0.085, and 51 milligrams per liter

  7. Comparison of mineral weathering and biomass nutrient uptake in two small forested watersheds underlain by quartzite bedrock, Catoctin Mountain, Maryland, USA

    USGS Publications Warehouse

    Rice, Karen; Price, Jason R.

    2014-01-01

    To quantify chemical weathering and biological uptake, mass-balance calculations were performed on two small forested watersheds located in the Blue Ridge Physiographic Province in north-central Maryland, USA. Both watersheds, Bear Branch (BB) and Fishing Creek Tributary (FCT), are underlain by relatively unreactive quartzite bedrock. Such unreactive bedrock and associated low chemical-weathering rates offer the opportunity to quantify biological processes operating within the watershed. Hydrologic and stream-water chemistry data were collected from the two watersheds for the 9-year period from June 1, 1990 to May 31, 1999. Of the two watersheds, FCT exhibited both higher chemical-weathering rates and biomass nutrient uptake rates, suggesting that forest biomass aggradation was limited by the rate of chemical weathering of the bedrock. Although the chemical-weathering rate in the FCT watershed was low relative to the global average, it masked the influence of biomass base-cation uptake on stream-water chemistry. Any differences in bedrock mineralogy between the two watersheds did not exert a significant influence on the overall weathering stoichiometry. The difference in chemical-weathering rates between the two watersheds is best explained by a larger proportion of reactive phyllitic layers within the bedrock of the FCT watershed. Although the stream gradient of BB is about two-times greater than that of FCT, its influence on chemical weathering appears to be negligible. The findings of this study support the biomass nutrient uptake stoichiometry of K1.0Mg1.1Ca0.97 previously determined for the study site. Investigations of the chemical weathering of relatively unreactive quartzite bedrock may provide insight into critical zone processes.

  8. Upland sediment supply and its relation to watershed sediment delivery in the contemporary mid-Atlantic Piedmont (U.S.A.)

    NASA Astrophysics Data System (ADS)

    Smith, S. M. C.; Wilcock, P. R.

    2015-03-01

    We use sediment accumulation in ponds and reservoirs to examine upland sediment sources and sinks in the Piedmont physiographic region of Maryland, USA. In zero-order and first-order watersheds, sediment yield is greatest from suburban land cover, followed by agriculture and forest. The idea that sediment yield is small from mature suburban development appears to not be correct. First-order channel enlargement is an important sediment source, causing sediment yield to increase from zero-order to first-order watersheds. Nonchannel sources provide one-third to two-thirds of the upland sediment load. Long-term sediment accumulation in a reservoir at fifth-order indicates that cumulative sediment load from upland areas is reduced by one-quarter by net valley bottom sedimentation. If upland supply exceeds the load delivered from a watershed, sediment must accumulate along valley bottoms. In our study watershed, net sedimentation rate (sedimentation less erosion) averaged over valley bottom area is 2.6 mm/y, a value that is similar to independent direct measurements of sedimentation and erosion in a nearby watershed. Evaluation of the relative contributions to sediment mass balance of upland supply, valley bottom sedimentation and erosion, and watershed delivery indicates that, if valley-bottom rates of sedimentation exceed erosion as indicated by recent studies, then the proportion of watershed sediment delivery derived from stream banks is necessarily small. Although sediment yield estimated from stream gage records is similar in magnitude to that from ponds for watersheds smaller than 20 km2, sediment yield from reservoir sedimentation is a factor of five larger than that estimated from gage records for watersheds larger than 140 km2. This observation confirms that the different methods provide very different estimates of sediment yield. This possibility is reinforced by a sediment yield of 14 Mg/km2/y from a gage immediately above a reservoir with a yield of 142 Mg

  9. Section 905(B) WRDA 86, Reconnaissance Study of Ecosystem Restoration for the Clinton River and Anchor Bay Watersheds, Macomb County and St. Clair County, Michigan

    DTIC Science & Technology

    2012-07-01

    aesthetics, and eutrophication or undesirable algae. These impairments can be attributed to elevated E. coli concentrations, excessive nutrients or...productivity that is greater than oligotrophic lakes, but less than eutrophic lakes. These lakes often support clear water, diverse and abundant beds of...those near the Clinton River outlet), can be eutrophic . Clinton River and Anchor Bay Watersheds Reconnaissance Study 16 Full body contact

  10. Relation of lead exposure to sediment ingestion in mute swans on the Chesapeake Bay, USA

    SciTech Connect

    Beyer, W.N.; Day, D.; Morton, A.; Pachepsky, Y.

    1998-11-01

    Although wildlife risk assessments are generally based on the accumulation of environmental contaminants through food chains, wildlife may also ingest contaminants incidentally with sediment. Forty-two mute swans (Cygnus olor) were collected from unpolluted portions of central Chesapeake Bay, Maryland, USA, in spring 1995, and their intestinal digesta were analyzed for 13 metals (aluminum [Al], boron, barium, cadmium, copper [Cu], iron, magnesium, manganese, nickel, lead [Pb], strontium, vanadium, and zinc) and for acid-insoluble ash, a marker of sediment. Swan livers and sediment samples also were analyzed for the same metals. Group method of data handling demonstrated that the digesta Al, which is associated with clays, was the best predictor of digesta Pb. Adding concentrations of other metals as predictors did not improve the accuracy of the estimates of Pb concentrations from Al concentrations. The r{sup 2} of the equation relating the log of digesta Pb to the log of digesta Al was 0.86, whereas the r{sup 2} of the equation relating the log of digesta Pb to the log of digesta acid-insoluble ash was 0.50. Accounting for the sediment ingested was critical to determining the exposure of mute swans to Pb, as well as to some of the other metals, and sediment ingestion should be considered in ecotoxicological risk assessments of waterfowl. The mean of 7.4% acid-insoluble ash in the digesta corresponded to an estimated 3.2% sediment in the diet. The Pb concentrations in the digesta were two to three times the concentration that would have been predicted from sediment Pb concentrations; presumably, the swans had ingested clays high in Pb that had settled on the vegetation. The swans were probably not exposed to high Cu concentrations but nevertheless had hepatic Cu concentrations that would be considered very high if found in other species.

  11. Integrating Sediment Clean Up and Watershed Management for Sinclair and Dyes Inlets, WA USA

    DTIC Science & Technology

    2005-01-01

    Naval Research 2004 Annual Report. KCHD (Kitsap County Health District). 2002. Water Quality Program 2000-2001 WATER QUALITY MONITORING REPORT...Sherrell, R.K. Johnston, F. Meriwether , T. Determan, W. Kendra, S. Magoon, S. Whitford, and J. Zimney. 2003. Assessment of Bacterial Contamination in...Bay, BC, SSWM (Kitsap County Public Works Surface and Stormwater Management). 2003. Annual Report 2003. US EPA 2000. EPA Superfund Record of

  12. Declining atmospheric sulfate deposition in a small agricultural watershed in central Pennsylvania, USA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sulfur emissions in the northeastern USA are only 20% of what they once were due the enactment of the Clean Air Act. While there are numerous reports of aquatic and forested ecosystems recovering as a result of the decline in sulfur deposition, there is little information describing such effects in ...

  13. Using Remotely Sensed Data and Watershed and Hydrodynamic Models to Evaluate the Effects of Land Cover Land Use Change on Aquatic Ecosystems in Mobile Bay, AL

    NASA Technical Reports Server (NTRS)

    Al-Hamdan, Mohammad Z.; Estes, Maurice G., Jr.; Judd, Chaeli; Thom, Ron; Woodruff, Dana; Ellis, Jean T.; Quattrochi, Dale; Watson, Brian; Rodriquez, Hugo; Johnson, Hoyt

    2012-01-01

    Alabama coastal systems have been subjected to increasing pressure from a variety of activities including urban and rural development, shoreline modifications, industrial activities, and dredging of shipping and navigation channels. The impacts on coastal ecosystems are often observed through the use of indicator species. One such indicator species for aquatic ecosystem health is submerged aquatic vegetation (SAV). Watershed and hydrodynamic modeling has been performed to evaluate the impact of land cover land use (LCLU) change in the two counties surrounding Mobile Bay (Mobile and Baldwin) on SAV stressors and controlling factors (temperature, salinity, and sediment) in the Mobile Bay estuary. Watershed modeling using the Loading Simulation Package in C++ (LSPC) was performed for all watersheds contiguous to Mobile Bay for LCLU scenarios in 1948, 1992, 2001, and 2030. Remotely sensed Landsat-derived National Land Cover Data (NLCD) were used in the 1992 and 2001 simulations after having been reclassified to a common classification scheme. The Prescott Spatial Growth Model was used to project the 2030 LCLU scenario based on current trends. The LSPC model simulations provided output on changes in flow, temperature, and sediment for 22 discharge points into the estuary. These results were inputted in the Environmental Fluid Dynamics Computer Code (EFDC) hydrodynamic model to generate data on changes in temperature, salinity, and sediment on a grid throughout Mobile Bay and adjacent estuaries. The changes in the aquatic ecosystem were used to perform an ecological analysis to evaluate the impact on SAV habitat suitability. This is the key product benefiting the Mobile Bay coastal environmental managers that integrates the influences of temperature, salinity, and sediment due to LCLU driven flow changes with the restoration potential of SAVs. Data products and results are being integrated into NOAA s EcoWatch and Gulf of Mexico Data Atlas online systems for

  14. Why metrics matter: evaluating policy choices for reactive nitrogen in the Chesapeake Bay watershed.

    PubMed

    Birch, Melissa B L; Gramig, Benjamin M; Moomaw, William R; Doering, Otto C; Reeling, Carson J

    2011-01-01

    Despite major efforts, the reduction of reactive nitrogen (Nr) using traditional metrics and policy tools for the Chesapeake Bay has slowed in recent years. In this article, we apply the concept of the Nitrogen Cascade to the chemically dynamic nature and multiple sources of Nr to examine the temporal and spatial movement of different forms of Nr through multiple ecosystems and media. We also demonstrate the benefit of using more than the traditional mass fluxes to set criteria for action. The use of multiple metrics provides additional information about where the most effective intervention point might be. Utilizing damage costs or mortality metrics demonstrates that even though the mass fluxes to the atmosphere are lower than direct releases to terrestrial and aquatic ecosystems, total damage costs to all ecosystems and health are higher because of the cascade of Nr and the associated damages, and because they exact a higher human health cost. Abatement costs for reducing Nr releases into the air are also lower. These findings have major implications for the use of multiple metrics and the additional benefits of expanding the scope of concern beyond the Bay itself and support improved coordination between the Clean Air and Clean Water Acts while restoring the Chesapeake Bay.

  15. Preliminary lithogeochemical map showing near-surface rock types in the Chesapeake Bay watershed, Virginia and Maryland

    USGS Publications Warehouse

    Peper, John D.; McCartan, Lucy B.; Horton, J. Wright; Reddy, James E.

    2001-01-01

    This preliminary experimental lithogeochemical map shows the distribution of rock types in the Virginia and Maryland parts of the Chesapeake Bay watershed. The map was produced digitally by classifying geologic-map units according to composition, mineralogy, and texture; rather than by age and stratigraphic relationships as shown on traditional geologic maps. This map differs from most lithologic maps in that the lithogeochemical unit classification distinguishes those rock units having key water-reactive minerals that may induce acid neutralization, or reduction, of hosted water at the weathering interface. The validity of these rock units, however, is independent of water chemistry, because the rock units are derived from geologic maps and rock descriptions. Areas of high soil carbon content, and sulfide metal deposits are also shown. Water-reactive minerals and their weathering reactions yield five lithogeochemical unit classes: 1) carbonate rock and calcareous rocks and sediments, the most acid-neutralizing; 2)carbonaceous-sulfidic rocks and sediments, oxygen-depleting and reducing; 3) quartzofeldspathic rocks and siliciclastic sediments, relatively weakly reactive with water; 4) mafic silicate rocks/sediments, oxygen consuming and high solute-load delivering; and, 5) the rarer calcareous-sulfidic (carbonaceous) rocks, neutralizing and reducing. Earlier studies in some parts of the map area have related solute loads in ground and stream waters to some aspects of bedrock lithology. More recent preliminary tests of relationships between four of the classes of mapped lithogeochemical units and ground water chemistry, in the Mid-Atlantic area using this map, have focused on and verified the nitrate-reducing and acid-neutralizing properties of some bedrock and unconsolidated aquifer rock types. Sulfide mineral deposits and their mine-tailings effects on waters are beginning to be studied by others. Additional testing of relationships among the lithogeochemical units

  16. Summary of suspended-sediment data for streams draining the Chesapeake Bay Watershed, water years 1952-2002

    USGS Publications Warehouse

    Gellis, Allen C.; Banks, William S.L.; Langland, Michael J.; Martucci, Sarah K.

    2004-01-01

    U.S. Geological Survey suspended-sediment data from 1952 to 2002 from selected stream-gaging stations draining the nontidal parts of the Chesapeake Bay Watershed were summarized to identify areas in the Watershed with high suspended-sediment loads, yields, and concentrations. The suspended-sediment load data were separated into two periods, 1952?1984 and 1985?2001. In 1985, the Chesapeake Bay Program began recommending sediment regulations, so 1985 represents an important break in the data. The instantaneous suspended-sediment concentration data were examined for the period 1985?2002. Suspended-sediment load data collected from 43 stations from 1952?1984, with a minimum of 3 years of record, indicated that the two highest average annual suspended-sediment loads were for stations on the main stem of the Potomac and Susquehanna Rivers. The highest average annual sediment yields and discharge-weighted sediment concentrations were for streams draining the metropolitan Washington, D.C. area, possibly related to urbanization. Data from 1985 through 2001 that were collected from 35 stations with a minimum of 3 years of record showed that the highest average annual suspended-sediment loads were also on the main stem of the Potomac and Susquehanna Rivers. Four of the six highest average annual sediment yields and discharge-weighted sediment concentrations for 1985?2001 were for stations draining to the Conestoga River, a tributary of the Susquehanna River. Examination of percentiles (10th, 50th, and 90th) of instantaneous suspended-sediment concentrations for 51 stations with a minimum of 3 years of data and at least 10 samples in a year indicated that streams that drain to the Conestoga River had the highest suspended-sediment concentrations. Sediment-transport curves for the 51 stations were separated into classes by drainage-area size. Five of the eight drainage-area classes showed that streams draining the Susquehanna River Basin had the highest suspended

  17. Dendrochronological assessment of drought severity indices for Panola Mountain Research Watershed, Georgia, U.S.A.

    NASA Astrophysics Data System (ADS)

    McKee, A.; Aulenbach, B. T.

    2015-12-01

    Quantifying the relation between drought severity and tree growth is important to predict future growth rates as climate change effects the frequency and severity of future droughts. Two commonly used metrics of drought severity are the Standardized Precipitation Index (SPI) and the Palmer Drought Severity Index (PDSI). These indices are often calculated from proximal weather station data and therefore may not be very accurate at the local watershed scale. The accuracy of these commonly used measures of drought severity was compared to a recently developed, locally calibrated model of water limitation based on the difference between potential and actual evapotranspiration (ETDIFF). Relative accuracies of the drought indices were assessed on the strength of correlations with a 20-year tree-ring index chronology (1986-2006) developed from 22 loblolly pine (Pinus taeda) trees in water-limited landscape positions at the Panola Mountain Research Watershed (PMRW), a 41-hectare forested watershed located in north-central Georgia. We used SPI and PDSI index values from the weather station located at the Atlanta Airport, approximately 36 kilometers from PMRW. ETDIFF was calculated based on precipitation, temperature, runoff, and solar radiation data collected at PMRW. Annual index values for all three drought indices were calculated as the mean value over the growing season (May to September). All three indices had significant Pearson correlations with the tree-ring index (p = 0.044, 0.007, 0.002 for SPI, PDSI, and ETDIFF, respectively). The ETDIFF method had the strongest correlation (R2 = 0.40) compared to SPI and PDSI results (R2 = 0.19 and 0.32, respectively). Results suggest SPI and PDSI provided a general measure of drought conditions, however, the locally calibrated model of water limitation appears to measure drought severity more accurately. Future studies on the ecological effects of drought may benefit from adopting ETDIFF as a measure of drought severity.

  18. Analysis of sediment retention in western riverine wetlands: the Yampa River watershed, Colorado, USA.

    PubMed

    Arp, Christopher D; Cooper, David J

    2004-03-01

    We quantified annual sediment deposition, bank erosion, and sediment budgets in nine riverine wetlands that represented a watershed continuum for 1 year in the unregulated Yampa River drainage basin in Colorado. One site was studied for 2 years to compare responses to peak flow variability. Annual mean sediment deposition ranged from 0.01 kg/m(2) along a first-order subalpine stream to 21.8 kg/m(2) at a sixth-order alluvial forest. Annual mean riverbank erosion ranged from 3 kg/m-of-bank at the first-order site to 1000 kg/m at the 6(th)-order site. Total sediment budgets were nearly balanced at six sites, while net export from bank erosion occurred at three sites. Both total sediment deposition (R(2) = 0.86, p < 0.01) and bank erosion (R(2) = 0.77, p < 0.01) were strongly related to bankfull height, and channel sinuosity and valley confinement helped to explain additional variability among sites. The texture and organic fraction of eroded and deposited sediment were relatively similar in most sites and varied among sites by watershed position. Our results indicate that bank erosion generally balances sediment deposition in riverine wetlands, and we found no distinct zones of sediment retention versus export on a watershed continuum. Zones of apparent disequilibrium can occur in unregulated rivers due to factors such as incised channels, beaver activity, and cattle grazing. A primary function of many western riverine wetlands is sediment exchange, not retention, which may operate by transforming materials and compounds in temporary sediment pools on floodplains. These results are considered in the context of the Hydrogeomorphic approach being implemented by the U.S. government for wetland resource management.

  19. Simulation of nutrient and sediment concentrations and loads in the Delaware inland bays watershed: Extension of the hydrologic and water-quality model to ungaged segments

    USGS Publications Warehouse

    Gutierrez-Magness, Angelica L.

    2006-01-01

    Rapid population increases, agriculture, and industrial practices have been identified as important sources of excessive nutrients and sediments in the Delaware Inland Bays watershed. The amount and effect of excessive nutrients and sediments in the Inland Bays watershed have been well documented by the Delaware Geological Survey, the Delaware Department of Natural Resources and Environmental Control, the U.S. Environmental Protection Agency's National Estuary Program, the Delaware Center for Inland Bays, the University of Delaware, and other agencies. This documentation and data previously were used to develop a hydrologic and water-quality model of the Delaware Inland Bays watershed to simulate nutrients and sediment concentrations and loads, and to calibrate the model by comparing concentrations and streamflow data at six stations in the watershed over a limited period of time (October 1998 through April 2000). Although the model predictions of nutrient and sediment concentrations for the calibrated segments were fairly accurate, the predictions for the 28 ungaged segments located near tidal areas, where stream data were not available, were above the range of values measured in the area. The cooperative study established in 2000 by the Delaware Department of Natural Resources and Environmental Control, the Delaware Geological Survey, and the U.S. Geological Survey was extended to evaluate the model predictions in ungaged segments and to ensure that the model, developed as a planning and management tool, could accurately predict nutrient and sediment concentrations within the measured range of values in the area. The evaluation of the predictions was limited to the period of calibration (1999) of the 2003 model. To develop estimates on ungaged watersheds, parameter values from calibrated segments are transferred to the ungaged segments; however, accurate predictions are unlikely where parameter transference is subject to error. The unexpected nutrient and

  20. Spatial Variations in the Relationships between Land Use and Water Quality across an Urbanization Gradient in the Watersheds of Northern Georgia, USA

    NASA Astrophysics Data System (ADS)

    Tu, Jun

    2013-01-01

    A spatial statistical technique, Geographically Weighted Regression (GWR) is applied to study the spatial variations in the relationships between four land use indicators, including percentages of urban land, forest, agricultural land, and wetland, and eight water quality indicators including specific conductance (SC), dissolved oxygen, dissolved nutrients, and dissolved organic carbon, in the watersheds of northern Georgia, USA. The results show that GWR has better model performance than ordinary least squares regression (OLS) to analyze the relationships between land use and water quality. There are great spatial variations in the relationships affected by the urbanization level of watersheds. The relationships between urban land and SC are stronger in less-urbanized watersheds, while those between urban land and dissolved nutrients are stronger in highly-urbanized watersheds. Percentage of forest is an indicator of good water quality. Agricultural land is usually associated with good water quality in highly-urbanized watersheds, but might be related to water pollution in less-urbanized watersheds. This study confirms the results obtained from a similar study in eastern Massachusetts, and so suggest that GWR technique is a very useful tool in water environmental research and also has the potential to be applied to other fields of environmental studies and management in other regions.

  1. Population genetic analyses are consistent with the introduction of Ceramium secundatum (Ceramiaceae, Rhodophyta) to Narragansett Bay, Rhode Island, USA.

    PubMed

    Bruce, Meghann R; Saunders, Gary W

    2015-11-01

    During ongoing DNA barcode (COI-5P) surveys of the macroalgal flora along the northwest Atlantic coast, we discovered a population of Ceramium secundatum in Narragansett Bay, Rhode Island, USA. This species is regarded as common and widespread in the northeast Atlantic, ranging from Norway to Morocco, but until now has not been reported from the western Atlantic. Several lines of evidence suggest that C. secundatum may be introduced to Narragansett Bay: (1) despite extensive collecting, specimens have only been obtained from a limited geographic range in the northwest Atlantic; (2) three other nonindigenous seaweed species are reportedly introduced in this region, which is thought to be a consequence of shipping; and (3) this species is introduced to South Africa and New Zealand. To investigate this suspected introduction, we applied population genetic analyses (using the cox2-3 spacer) to compare the Narragansett Bay C. secundatum population to native populations in the Republic of Ireland and the United Kingdom. Collectively, analyses of biogeographical and molecular data indicate that C. secundatum is likely introduced to Narragansett Bay. The implications of this discovery are discussed.

  2. A multitemporal remote sensing approach to parsimonious streamflow modeling in a southcentral Texas watershed, USA

    NASA Astrophysics Data System (ADS)

    Weissling, B. P.; Xie, H.; Murray, K. E.

    2007-01-01

    Soil moisture condition plays a vital role in a watershed's hydrologic response to a precipitation event and is thus parameterized in most, if not all, rainfall-runoff models. Yet the soil moisture condition antecedent to an event has proven difficult to quantify both spatially and temporally. This study assesses the potential to parameterize a parsimonious streamflow prediction model solely utilizing precipitation records and multi-temporal remotely sensed biophysical variables (i.e.~from Moderate Resolution Imaging Spectroradiometer (MODIS)/Terra satellite). This study is conducted on a 1420 km2 rural watershed in the Guadalupe River basin of southcentral Texas, a basin prone to catastrophic flooding from convective precipitation events. A multiple regression model, accounting for 78% of the variance of observed streamflow for calendar year 2004, was developed based on gauged precipitation, land surface temperature, and enhanced vegetation Index (EVI), on an 8-day interval. These results compared favorably with streamflow estimations utilizing the Natural Resources Conservation Service (NRCS) curve number method and the 5-day antecedent moisture model. This approach has great potential for developing near real-time predictive models for flood forecasting and can be used as a tool for flood management in any region for which similar remotely sensed data are available.

  3. Tracing hydrologic pathways at the Panola Mountain research watershed, Georgia, USA

    USGS Publications Warehouse

    Peters, N.E.; Ratcliffe, E.B.

    1997-01-01

    An analysis of Cl- concentrations and fluxes at the Panola Mountain Research Watershed indicates that Cl- may be effectively used to differentiate 'new' and 'old' water flow through the hillslope and their respective contributions to streamwater. Rainfall and throughfall, the 'new' water inputs, are marked by low Cl- concentrations (15 ??eq 1-1). Stormwater moves rapidly to depth along preferred pathways in a deciduous forest hillslope, as evidenced by low concentrations (20 ??eq 1-1) in mobile soil water from zero-tension stainless-steel pan lysimeters. 'Old' waters, matrix soil waters and groundwater, typically have high concentrations (20 ??eq 1-1). Timing of soil water transport is not sufficiently rapid to suggest that soil water from the hillslope contributes to streamwater for an individual rainstorm. The source of streamflow, therefore, must be a combination of channel interception, runoff from near-channel areas, and runoff from a 3-ha bedrock outcrop in the headwaters. Groundwater contribution to streamflow was estimated using Cl- concentrations of throughfall and groundwater as the two end members for a two-component hydrograph separation. For the study period, groundwater contributed 79% of the runoff and from 1985 to 1995, contributed 75% of the runoff. Rainfall was the source of 45% of the Cl- flux from the watershed in the long term; the remaining Cl- is hypothesized to be derived from dry deposition, consistent with the enrichment noted for throughfall. At peak flow during individual rainstorms, 'new' water can contribute 95% of the runoff.

  4. Tracing hydrologic pathways at the Panola Mountain Research Watershed, Georgia, USA

    USGS Publications Warehouse

    Peters, N.E.; Ratcliffe, E.B.

    1997-01-01

    An analysis of Cl- concentrations and fluxes at the Panola Mountain Research Watershed indicates that Cl- may be effectively used to differentiate "new" and "old" water flow through the hillslope and their respective contributions to streamwater. Rainfall and throughfall, the "new" water inputs, are marked by low Cl- concentrations (20 ??eq l-1). Timing of soil water transport is not sufficiently rapid to suggest that soil water from the hillslope contributes to streamwater for an individual rainstorm. The source of streamflow, therefore, must be a combination of channel interception, runoff from near-channel areas, and runoff from a 3-ha bedrock outcrop in the headwaters. Groundwater contribution to streamflow was estimated using Cl- concentrations of throughfall and groundwater as the two end members for a two-component hydrograph separation. For the study period, groundwater contributed 79% of the runoff and from 1985 to 1995, contributed 75% of the runoff. Rainfall was the source of 45% of the Cl- flux from the watershed in the long term; the remaining Cl- is hypothesized to be derived from dry deposition, consistent with the enrichment noted for throughfall. At peak flow during individual rainstorms, "new" water can contribute 95% of the runoff.

  5. Tracing hydrologic pathways using chloride at the Panola mountain research watershed, Georgia, USA

    USGS Publications Warehouse

    Peters, N.E.; Ratcliffe, E.B.

    1998-01-01

    An analysis of chloride (Cl-) concentrations and fluxes at the 41 ha Panola Mountain Research Watershed indicates that Cl- may be used effectively to differentiate 'new' and 'old' water flow through the hillslope and their respective contributions to streamwater. Rainfall and throughfall, the 'new' water inputs, are marked by low Cl- concentrations (30 ??eq L-1). Timing of soil water transport is not sufficiently rapid to suggest that soil water from this hillslope site (20 m from the stream) contributes to streamwater during individual rainstorms. The source of streamflow, therefore, must be a combination of channel interception, overland flow and soil water from nearchannel areas, and run off from a 3 ha bedrock outcrop in the headwaters Groundwater contribution to streamflow was estimated using Cl- concentrations of throughfall and groundwater as the two end members for a two-component hydrograph separation. For the study period, groundwater contributed 79% of the streamflow and from 1985 to 1995, contributed 75% of the streamflow. Rainfall was the source of 45% of the Cl- flux from the watershed in the long term; the remaining Cl- is hypothesized to be derived from dry deposition, consistent with the enrichment noted for throughfall. At peak flow during individual rainstorms, 'new' water can contribute 95% of the runoff.

  6. Effects of Climate Variability and Accelerated Forest Thinning on Watershed-Scale Runoff in Southwestern USA Ponderosa Pine Forests

    PubMed Central

    Robles, Marcos D.; Marshall, Robert M.; O'Donnell, Frances; Smith, Edward B.; Haney, Jeanmarie A.; Gori, David F.

    2014-01-01

    The recent mortality of up to 20% of forests and woodlands in the southwestern United States, along with declining stream flows and projected future water shortages, heightens the need to understand how management practices can enhance forest resilience and functioning under unprecedented scales of drought and wildfire. To address this challenge, a combination of mechanical thinning and fire treatments are planned for 238,000 hectares (588,000 acres) of ponderosa pine (Pinus ponderosa) forests across central Arizona, USA. Mechanical thinning can increase runoff at fine scales, as well as reduce fire risk and tree water stress during drought, but the effects of this practice have not been studied at scales commensurate with recent forest disturbances or under a highly variable climate. Modifying a historical runoff model, we constructed scenarios to estimate increases in runoff from thinning ponderosa pine at the landscape and watershed scales based on driving variables: pace, extent and intensity of forest treatments and variability in winter precipitation. We found that runoff on thinned forests was about 20% greater than unthinned forests, regardless of whether treatments occurred in a drought or pluvial period. The magnitude of this increase is similar to observed declines in snowpack for the region, suggesting that accelerated thinning may lessen runoff losses due to warming effects. Gains in runoff were temporary (six years after treatment) and modest when compared to mean annual runoff from the study watersheds (0–3%). Nonetheless gains observed during drought periods could play a role in augmenting river flows on a seasonal basis, improving conditions for water-dependent natural resources, as well as benefit water supplies for downstream communities. Results of this study and others suggest that accelerated forest thinning at large scales could improve the water balance and resilience of forests and sustain the ecosystem services they provide. PMID

  7. Effects of climate variability and accelerated forest thinning on watershed-scale runoff in southwestern USA ponderosa pine forests.

    PubMed

    Robles, Marcos D; Marshall, Robert M; O'Donnell, Frances; Smith, Edward B; Haney, Jeanmarie A; Gori, David F

    2014-01-01

    The recent mortality of up to 20% of forests and woodlands in the southwestern United States, along with declining stream flows and projected future water shortages, heightens the need to understand how management practices can enhance forest resilience and functioning under unprecedented scales of drought and wildfire. To address this challenge, a combination of mechanical thinning and fire treatments are planned for 238,000 hectares (588,000 acres) of ponderosa pine (Pinus ponderosa) forests across central Arizona, USA. Mechanical thinning can increase runoff at fine scales, as well as reduce fire risk and tree water stress during drought, but the effects of this practice have not been studied at scales commensurate with recent forest disturbances or under a highly variable climate. Modifying a historical runoff model, we constructed scenarios to estimate increases in runoff from thinning ponderosa pine at the landscape and watershed scales based on driving variables: pace, extent and intensity of forest treatments and variability in winter precipitation. We found that runoff on thinned forests was about 20% greater than unthinned forests, regardless of whether treatments occurred in a drought or pluvial period. The magnitude of this increase is similar to observed declines in snowpack for the region, suggesting that accelerated thinning may lessen runoff losses due to warming effects. Gains in runoff were temporary (six years after treatment) and modest when compared to mean annual runoff from the study watersheds (0-3%). Nonetheless gains observed during drought periods could play a role in augmenting river flows on a seasonal basis, improving conditions for water-dependent natural resources, as well as benefit water supplies for downstream communities. Results of this study and others suggest that accelerated forest thinning at large scales could improve the water balance and resilience of forests and sustain the ecosystem services they provide.

  8. Developing a regional retrospective ensemble precipitation dataset for watershed hydrology modeling, Idaho, USA

    NASA Astrophysics Data System (ADS)

    Flores, A. N.; Smith, K.; LaPorte, P.

    2011-12-01

    Applications like flood forecasting, military trafficability assessment, and slope stability analysis necessitate the use of models capable of resolving hydrologic states and fluxes at spatial scales of hillslopes (e.g., 10s to 100s m). These models typically require precipitation forcings at spatial scales of kilometers or better and time intervals of hours. Yet in especially rugged terrain that typifies much of the Western US and throughout much of the developing world, precipitation data at these spatiotemporal resolutions is difficult to come by. Ground-based weather radars have significant problems in high-relief settings and are sparsely located, leaving significant gaps in coverage and high uncertainties. Precipitation gages provide accurate data at points but are very sparsely located and their placement is often not representative, yielding significant coverage gaps in a spatial and physiographic sense. Numerical weather prediction efforts have made precipitation data, including critically important information on precipitation phase, available globally and in near real-time. However, these datasets present watershed modelers with two problems: (1) spatial scales of many of these datasets are tens of kilometers or coarser, (2) numerical weather models used to generate these datasets include a land surface parameterization that in some circumstances can significantly affect precipitation predictions. We report on the development of a regional precipitation dataset for Idaho that leverages: (1) a dataset derived from a numerical weather prediction model, (2) gages within Idaho that report hourly precipitation data, and (3) a long-term precipitation climatology dataset. Hourly precipitation estimates from the Modern Era Retrospective-analysis for Research and Applications (MERRA) are stochastically downscaled using a hybrid orographic and statistical model from their native resolution (1/2 x 2/3 degrees) to a resolution of approximately 1 km. Downscaled

  9. Trends in Surface-Water Nitrate-N Concentrations and Loads from Predominantly-Forested Watersheds of the Chesapeake Bay Basin

    NASA Astrophysics Data System (ADS)

    Eshleman, K. N.

    2011-12-01

    Water quality monitoring data from streams and rivers provide the "gold standard" by which progress toward achieving real reductions in nutrient loadings to Chesapeake Bay must ultimately be assessed. The most recent trend results posted at the Chesapeake Bay Program (CBP) website reveal that a substantial percentage of tributaries are now showing long-term declines in flow-adjusted concentrations of nutrients and sediments: 22 sites showed statistically significant (p < 0.05) downward trends (1985-2010) in flow-adjusted concentrations, two sites showed upward trends, and eight sites showed no trend. Based on the data, the CBP has drawn the following conclusion: "At many monitored locations, long-term trends indicate that management actions, such as pollution controls for improved wastewater treatment plants and practices to reduce nutrients on farms and suburban lands, have reduced concentrations of nitrogen." But could this conclusion be pre-mature? I recently undertook a comparable analysis of long-term nitrate-N trends for a different group of watersheds (all located in the Chesapeake Bay watershed with long data records); this group includes nine watersheds that are predominantly (i.e., >75%) forested, plus five other Potomac River subwatersheds added for comparison. Based on comparable data and analytical methods to those used by CBP partners and USGS, 13 of the 14 sites-including both Potomac River stations (Chain Bridge at Washington DC and Hancock, Maryland)-showed statistically significant decreasing linear trends in annual flow-weighted nitrate-N concentration. Only one station-the heavily agricultural Upper Monocacy River-did not show a statistically significant (p < 0.05) trend. Five of the predominantly-forested watersheds also showed statistically significant decreasing trends in annual nitrate-N loads, and none of the stations showed a trend in annual runoff presumably due to high inter-annual hydroclimatological variability. While the largest

  10. Mercury contamination in three species of anuran amphibians from the Cache Creek Watershed, California, USA.

    PubMed

    Hothem, Roger L; Jennings, Mark R; Crayon, John J

    2010-04-01

    Fish and wildlife may bioaccumulate mercury (Hg) to levels that adversely affect reproduction, growth, and survival. Sources of Hg within the Cache Creek Watershed in northern California have been identified, and concentrations of Hg in invertebrates and fish have been documented. However, bioaccumulation of Hg by amphibians has not been evaluated. In this study, adult and juvenile American bullfrogs (Lithobates catesbeianus) and foothill yellow-legged frogs (Rana boylii), adult Northern Pacific treefrogs (Pseudacris regilla), and larval bullfrogs were collected and analyzed for total Hg. One or more species of amphibians from 40% of the 35 sites had mean Hg concentrations greater than the US Environmental Protection Agency's tissue residue criterion for fish (0.3 microg/g). Of the bullfrog tissues analyzed, the liver had the highest concentrations of both total Hg and methyl mercury. Total Hg in carcasses of bullfrogs was highly correlated with total Hg in leg muscle, the tissue most often consumed by humans.

  11. Reconstructing the natural hydrology of the San Francisco Bay-Delta watershed

    NASA Astrophysics Data System (ADS)

    Fox, P.; Hutton, P. H.; Howes, D. J.; Draper, A. J.; Sears, L.

    2015-10-01

    We evaluated the impact of landscape changes on the amount of delta outflow reaching San Francisco Bay. The natural landscape was reconstructed and water balances were used to estimate the long-term annual average delta outflow that would have occurred under natural landscape conditions if the climate from 1922 to 2009 were to repeat itself. These outflows are referred to as natural delta outflows and are the first published estimate of natural delta outflow. These natural delta outflows were then compared with current delta outflows for the same climate and existing landscape, including its re-engineered system of reservoirs, canals, aqueducts, and pumping plants. This analysis shows that the long-term, annual average delta outflow under current conditions is consistent with outflow under natural landscape conditions. The amount of water currently used by farms, cities, and others is about equal to the amount of water formerly used by native vegetation. Development of water resources in California's Central Valley transferred water formerly used by native vegetation to new beneficial uses without substantially reducing the long-term annual average supply to the San Francisco Bay-Delta estuary. Based on this finding, it is unlikely that observed declines in native freshwater aquatic species are the result of annual average delta outflow reductions.

  12. Predicting watershed sediment yields after wildland fire with the InVEST sediment retention model at large geographic extent in the western USA: accuracy and uncertainties

    NASA Astrophysics Data System (ADS)

    Sankey, J. B.; Kreitler, J.; McVay, J.; Hawbaker, T. J.; Vaillant, N.; Lowe, S. E.

    2014-12-01

    Wildland fire is a primary threat to watersheds that can impact water supply through increased sedimentation, water quality decline, and change the timing and amount of runoff leading to increased risk from flood and sediment natural hazards. It is of great societal importance in the western USA and throughout the world to improve understanding of how changing fire frequency, extent, and location, in conjunction with fuel treatments will affect watersheds and the ecosystem services they supply to communities. In this work we assess the utility of the InVEST Sediment Retention Model to accurately characterize vulnerability of burned watersheds to erosion and sedimentation. The InVEST tools are GIS-based implementations of common process models, engineered for high-end computing to allow the faster simulation of larger landscapes and incorporation into decision-making. The InVEST Sediment Retention Model is based on common soil erosion models (e.g., RUSLE -Revised Universal Soil Loss Equation) and determines which areas of the landscape contribute the greatest sediment loads to a hydrological network and conversely evaluate the ecosystem service of sediment retention on a watershed basis. We evaluate the accuracy and uncertainties for InVEST predictions of increased sedimentation after fire, using measured post-fire sedimentation rates available for many watersheds in different rainfall regimes throughout the western USA from an existing, large USGS database of post-fire sediment yield [synthesized in Moody J, Martin D (2009) Synthesis of sediment yields after wildland fire in different rainfall regimes in the western United States. International Journal of Wildland Fire 18: 96-115]. The ultimate goal of this work is to calibrate and implement the model to accurately predict variability in post-fire sediment yield as a function of future landscape heterogeneity predicted by wildfire simulations, and future landscape fuel treatment scenarios, within watersheds.

  13. Evidence for natural molecular hydrogen seepage associated with Carolina bays (surficial, ovoid depressions on the Atlantic Coastal Plain, Province of the USA)

    NASA Astrophysics Data System (ADS)

    Zgonnik, Viacheslav; Beaumont, Valérie; Deville, Eric; Larin, Nikolay; Pillot, Daniel; Farrell, Kathleen M.

    2015-12-01

    A study of soil gases was made in North Carolina (USA) in and around morphological depressions called "Carolina bays." This type of depression is observed over the Atlantic coastal plains of the USA, but their origin remains debated. Significant concentrations of molecular hydrogen (H2) were detected, notably around the bays. These measurements suggest that Carolina bays are the surficial expression of fluid flow pathways for hydrogen gas moving from depth to the surface. The potential mechanisms of H2 production and transport and the geological controls on the fluid migration pathways are discussed, with reference to the hypothesis that Carolina bays are the result of local collapses caused by the alteration of rock along the deep pathways of H2 migrating towards the surface. The present H2 seepages are comparable to those in similar structures previously observed in the East European craton.

  14. An historical perspective on eutrophication in the Pensacola Bay Estuary, FL, USA

    EPA Science Inventory

    In this chapter, we provide a brief description of the Pensacola Bay estuary, examining the available historical data for evidence of trends in eutrophication within the estuary. Common to many industrialized estuaries, Pensacola Bay has been subjected to unregulated point source...

  15. Flow and geochemistry of groundwater beneath a back-barrier lagoon: The subterranean estuary at Chincoteague Bay, Maryland, USA

    USGS Publications Warehouse

    Bratton, J.F.; Böhlke, J.K.; Krantz, D.E.; Tobias, C.R.

    2009-01-01

    To better understand large-scale interactions between fresh and saline groundwater beneath an Atlantic coastal estuary, an offshore drilling and sampling study was performed in a large barrier-bounded lagoon, Chincoteague Bay, Maryland, USA. Groundwater that was significantly fresher than overlying bay water was found in shallow plumes up to 8??m thick extending more than 1700??m offshore. Groundwater saltier than bay surface water was found locally beneath the lagoon and the barrier island, indicating recharge by saline water concentrated by evaporation prior to infiltration. Steep salinity and nutrient gradients occur within a few meters of the sediment surface in most locations studied, with buried peats and estuarine muds acting as confining units. Groundwater ages were generally more than 50??years in both fresh and brackish waters as deep as 23??m below the bay bottom. Water chemistry and isotopic data indicate that freshened plumes beneath the estuary are mixtures of water originally recharged on land and varying amounts of estuarine surface water that circulated through the bay floor, possibly at some distance from the sampling location. Ammonium is the dominant fixed nitrogen species in saline groundwater beneath the estuary at the locations sampled. Isotopic and dissolved-gas data from one location indicate that denitrification within the subsurface flow system removed terrestrial nitrate from fresh groundwater prior to discharge along the western side of the estuary. Similar situations, with one or more shallow semi-confined flow systems where groundwater geochemistry is strongly influenced by circulation of surface estuary water through organic-rich sediments, may be common on the Atlantic margin and elsewhere.

  16. Albino mutation rates in red mangroves (Rhizophora mangle L.) as a bioassay of contamination history in Tampa Bay, Florida, USA

    USGS Publications Warehouse

    Proffitt, C.E.; Travis, S.E.

    2005-01-01

    We assessed the sensitivity of a viviparous estuarine tree species, Rhizophora mangle, to historic sublethal mutagenic stress across a fine spatial scale by comparing the frequency of trees producing albino propagules in historically contaminated (n=4) and uncontaminated (n=11) forests in Tampa Bay, Florida, USA. Data from uncontaminated forests were used to provide estimates of background mutation rates. We also determined whether other fitness parameters were negatively correlated with mutagenic stress (e.g., degree of outcrossing and numbers of reproducing trees km-1). Contaminated sites in Tampa Bay had significantly higher frequencies of trees that were heterozygous for albinism per 1000 total reproducing trees (FHT) than uncontaminated forests (mean ?? SE: 11.4 ?? 4.3 vs 4.3 ?? 0.73, P 25 yrs of subsequent recruitment and tree replacement may have allowed an initial elevation in the FHT to decay. Patterns of FHT were not explained by distance from the bay mouth or the degree of urbanization. However, there was a significant positive relationship between tree size and FHT (r=0.83, P<0.018), which suggests that forests with older or larger trees provide a more lasting record of cumulative mutagenic stress. No other fitness parameters correlated with FHT. There was a difference in FHT between two latitudes, as determined by comparing Tampa Bay with literature values for Puerto Rico. The sensitivity of this bioassay for the effects of mutagens will facilitate future monitoring of contamination events and comparisons of bay-wide recovery in future decades. Development of a database of FHT values for a range of subtropical and tropical estuaries is underway that will provide a baseline against which to compare mutational consequences of global change. ?? 2005, The Society of Wetland Scientists.

  17. The Deep Biosphere in Terrestrial Sediments in the Chesapeake Bay Area, Virginia, USA

    PubMed Central

    Breuker, Anja; Köweker, Gerrit; Blazejak, Anna; Schippers, Axel

    2011-01-01

    For the first time quantitative data on the abundance of Bacteria, Archaea, and Eukarya in deep terrestrial sediments are provided using multiple methods (total cell counting, quantitative real-time PCR, Q-PCR and catalyzed reporter deposition–fluorescence in situ hybridization, CARD–FISH). The oligotrophic (organic carbon content of ∼0.2%) deep terrestrial sediments in the Chesapeake Bay area at Eyreville, Virginia, USA, were drilled and sampled up to a depth of 140 m in 2006. The possibility of contamination during drilling was checked using fluorescent microspheres. Total cell counts decreased from 109 to 106 cells/g dry weight within the uppermost 20 m, and did not further decrease with depth below. Within the top 7 m, a significant proportion of the total cell counts could be detected with CARD–FISH. The CARD–FISH numbers for Bacteria were about an order of magnitude higher than those for Archaea. The dominance of Bacteria over Archaea was confirmed by Q-PCR. The down core quantitative distribution of prokaryotic and eukaryotic small subunit ribosomal RNA genes as well as functional genes involved in different biogeochemical processes was revealed by Q-PCR for the uppermost 10 m and for 80–140 m depth. Eukarya and the Fe(III)- and Mn(IV)-reducing bacterial group Geobacteriaceae were almost exclusively found in the uppermost meter (arable soil), where reactive iron was detected in higher amounts. The bacterial candidate division JS-1 and the classes Anaerolineae and Caldilineae of the phylum Chloroflexi, highly abundant in marine sediments, were found up to the maximum sampling depth in high copy numbers at this terrestrial site as well. A similar high abundance of the functional gene cbbL encoding for the large subunit of RubisCO suggests that autotrophic microorganisms could be relevant in addition to heterotrophs. The functional gene aprA of sulfate reducing bacteria was found within distinct layers up to ca. 100 m depth in low copy

  18. The deep biosphere in terrestrial sediments in the chesapeake bay area, virginia, USA.

    PubMed

    Breuker, Anja; Köweker, Gerrit; Blazejak, Anna; Schippers, Axel

    2011-01-01

    For the first time quantitative data on the abundance of Bacteria, Archaea, and Eukarya in deep terrestrial sediments are provided using multiple methods (total cell counting, quantitative real-time PCR, Q-PCR and catalyzed reporter deposition-fluorescence in situ hybridization, CARD-FISH). The oligotrophic (organic carbon content of ∼0.2%) deep terrestrial sediments in the Chesapeake Bay area at Eyreville, Virginia, USA, were drilled and sampled up to a depth of 140 m in 2006. The possibility of contamination during drilling was checked using fluorescent microspheres. Total cell counts decreased from 10(9) to 10(6) cells/g dry weight within the uppermost 20 m, and did not further decrease with depth below. Within the top 7 m, a significant proportion of the total cell counts could be detected with CARD-FISH. The CARD-FISH numbers for Bacteria were about an order of magnitude higher than those for Archaea. The dominance of Bacteria over Archaea was confirmed by Q-PCR. The down core quantitative distribution of prokaryotic and eukaryotic small subunit ribosomal RNA genes as well as functional genes involved in different biogeochemical processes was revealed by Q-PCR for the uppermost 10 m and for 80-140 m depth. Eukarya and the Fe(III)- and Mn(IV)-reducing bacterial group Geobacteriaceae were almost exclusively found in the uppermost meter (arable soil), where reactive iron was detected in higher amounts. The bacterial candidate division JS-1 and the classes Anaerolineae and Caldilineae of the phylum Chloroflexi, highly abundant in marine sediments, were found up to the maximum sampling depth in high copy numbers at this terrestrial site as well. A similar high abundance of the functional gene cbbL encoding for the large subunit of RubisCO suggests that autotrophic microorganisms could be relevant in addition to heterotrophs. The functional gene aprA of sulfate reducing bacteria was found within distinct layers up to ca. 100 m depth in low copy numbers

  19. Hotter Drought, Disturbance Process Thresholds, and Reorganization of Forest Ecosystems and Watersheds in the Southwestern USA, and Beyond

    NASA Astrophysics Data System (ADS)

    Allen, C. D.

    2015-12-01

    Extensive high-severity wildfires and drought-induced tree mortality (including drought-and-heat-related insect pest outbreaks), along with associated major alterations of watershed conditions and hydrological processes, have intensified over the last two decades in Southwest USA forests and woodlands—on a scale unseen regionally since at least pre-1900, and quite possibly not for millennia, based on diverse lines of paleo-ecological and geomorphic evidence. Historical land-use patterns, decadal-scale climate variability (e.g., drought linked to the Pacific Decadal Oscillation), and warming temperatures in recent decades (resulting in "hotter drought" conditions) have been important interactive drivers of observed nonlinear threshold changes in these forest disturbance processes. In response, Southwest forest landscapes have been rapidly transitioning toward more open and drought-tolerant ecosystems, with altered ecohydrological patterns. If regional temperatures increase as projected by climate models, multiple lines of evidence (experiments, observations, empirical models, process models) suggest that Southwest drought stress after ca. 2050 will increasingly exceed that of the most severe droughts in the past 1,000 years, putting current historical forests at grave risk—in particular the tallest (& often the oldest) trees and forests. These findings point toward the emergence of increasingly novel vegetation patterns over the course of this century. Forests globally exhibit great diversity in environmental drivers, histories, dominant ecological patterns and processes, biodiversity, etc., which are expected to produce diverse forest responses (and levels of resilience) to projected global changes in climate and human uses this century. Even given this planetary diversity of forests and expected global change responses, the observed reorganization of forests underway in the Southwest USA - driven by the convergence of changes in land use patterns, disturbance

  20. Evaluating the effect of different vegetative filter strip designs on sediment movement in an agricultural watershed using LISEM, Iowa, USA

    NASA Astrophysics Data System (ADS)

    Luquin Oroz, Eduardo; Cruse, Rick; Baartman, Jantiene; Keesstra, Saskia

    2016-04-01

    Although restoration of native vegetation in vulnerable areas would decrease soil loss, this approach is not feasible in communities that base their income on agriculture. However, an alternative exists: strategically placing a small percentage of vegetative filter strips (VFS) within agriculture fields for erosion control. Factors influencing their effectiveness are shallow conditions, vegetation type, filter strip width, slope, soil type, and rainfall characteristics. Generally, the first few meters of the strip are where most sediments deposit. For slopes higher than 10%, effectiveness decreases with increasing slope gradient. Usually, high rainfall intensity and sediment load in overland flow decrease vegetative filter strips' effectiveness. Nowadays, Iowa (USA), experiences increasingly stronger rainstorms; climate change is expected to increase rainfall erosive forces between 16 to 58%. Thus, there is a need to obtain new insights about strip design and its influence on sediment dynamics. Therefore, the objective of this study is to analyze strip design (width) impact on soil and water movement. To do so, different strip widths (no strips, 1.5, 3, 5, 7.5 and 10 meters wide) were analyzed under four rainfall intensities (increments of 10, 25, 50 and 75%) The event-based, hydrological and soil erosion model LISEM was used to simulate different scenarios. The model has been calibrated with data from 3-ha 'Interim 1' watershed, which is part of Walnut Creek (Iowa, USA). During a single event with sediment load, on July 18th 2010, intensities reached up to 80 mm/h. Two different land covers exist: (i) perennial vegetation, which has prairie vegetation covering patches and strips; and (ii) row crop agriculture where corn and soybeans are the main two crops in the area. Based on the different combination of widths and intensities, 24 scenarios were generated. At the moment, the model is on the final part of the calibration; scenario results will be presented on the

  1. Using Remotely Sensed Data and Watershed and Hydrodynamic Models to Evaluate the Effects of Land Cover Land Use Change on Aquatic Ecosystems in Mobile Bay, AL

    NASA Technical Reports Server (NTRS)

    Al-Hamdan, Mohammad; Estes, Maurice G., Jr.; Judd, Chaeli; Woodruff, Dana; Ellis, Jean; Quattrochi, Dale; Watson, Brian; Rodriquez, Hugo; Johnson, Hoyt

    2012-01-01

    Alabama coastal systems have been subjected to increasing pressure from a variety of activities including urban and rural development, shoreline modifications, industrial activities, and dredging of shipping and navigation channels. The impacts on coastal ecosystems are often observed through the use of indicator species. One such indicator species for aquatic ecosystem health is submerged aquatic vegetation (SAV). Watershed and hydrodynamic modeling has been performed to evaluate the impact of land cover land use (LCLU) change in the two counties surrounding Mobile Bay (Mobile and Baldwin) on SAV stressors and controlling factors (temperature, salinity, and sediment) in the Mobile Bay estuary. Watershed modeling using the Loading Simulation Package in C++ (LSPC) was performed for all watersheds contiguous to Mobile Bay for LCLU scenarios in 1948, 1992, 2001, and 2030. Remotely sensed Landsat-derived National Land Cover Data (NLCD) were used in the 1992 and 2001 simulations after having been reclassified to a common classification scheme. The Prescott Spatial Growth Model was used to project the 2030 LCLU scenario based on current trends. The LSPC model simulations provided output on changes in flow, temperature, and sediment for 22 discharge points into the estuary. These results were inputted in the Environmental Fluid Dynamics Computer Code (EFDC) hydrodynamic model to generate data on changes in temperature, salinity, and sediment on a grid throughout Mobile Bay and adjacent estuaries. The changes in the aquatic ecosystem were used to perform an ecological analysis to evaluate the impact on SAV habitat suitability. This is the key product benefiting the Mobile Bay coastal environmental managers that integrates the influences of temperature, salinity, and sediment due to LCLU driven flow changes with the restoration potential of SAVs. Data products and results are being integrated into NOAA s EcoWatch and Gulf of Mexico Data Atlas online systems for

  2. Application of Watershed Deposition Tool to Estimate from CMAQ Simulations of the Atmospheric Deposition of Nitrogen to Tampa Bay and Its Watershed

    EPA Science Inventory

    The USEPA has developed Watershed Deposition Tool (WDT) to calculate from the Community Multiscale Air Quality (CMAQ) model output the nitrogen, sulfur, and mercury deposition rates to watersheds and their sub-basins. The CMAQ model simulates from first principles the transport, ...

  3. Identification of largemouth bass virus in the introduced Northern snakehead inhabiting the Cheasapeake Bay watershed

    USGS Publications Warehouse

    Iwanowicz, Luke R.; Densmore, Christine L.; Hahn, Cassidy M.; McAllister, Phillip; Odenkirk, John

    2013-01-01

    The Northern Snakehead Channa argus is an introduced species that now inhabits the Chesapeake Bay. During a preliminary survey for introduced pathogens possibly harbored by these fish in Virginia waters, a filterable agent was isolated from five specimens that produced cytopathic effects in BF-2 cells. Based on PCR amplification and partial sequencing of the major capsid protein (MCP), DNA polymerase (DNApol), and DNA methyltransferase (Mtase) genes, the isolates were identified as Largemouth Bass virus (LMBV). Nucleotide sequences of the MCP (492 bp) and DNApol (419 pb) genes were 100% identical to those of LMBV. The nucleotide sequence of the Mtase (206 bp) gene was 99.5% identical to that of LMBV, and the single nucleotide substitution did not lead to a predicted amino acid coding change. This is the first report of LMBV from the Northern Snakehead, and provides evidence that noncentrarchid fishes may be susceptible to this virus.

  4. Isotope hydrology and baseflow geochemistry in natural and human-altered watersheds in the Inland Pacific Northwest, USA.

    PubMed

    Sánchez-Murillo, Ricardo; Brooks, Erin S; Elliot, William J; Boll, Jan

    2015-01-01

    This study presents a stable isotope hydrology and geochemical analysis in the inland Pacific Northwest (PNW) of the USA. Isotope ratios were used to estimate mean transit times (MTTs) in natural and human-altered watersheds using the FLOWPC program. Isotope ratios in precipitation resulted in a regional meteoric water line of δ(2)H = 7.42·δ(18)O + 0.88 (n = 316; r(2) = 0.97). Isotope compositions exhibited a strong temperature-dependent seasonality. Despite this seasonal variation, the stream δ(18)O variation was small. A significant regression (τ = 0.11D(-1.09); r(2) = 0.83) between baseflow MTTs and the damping ratio was found. Baseflow MTTs ranged from 0.4 to 0.6 years (human-altered), 0.7 to 1.7 years (mining-altered), and 0.7 to 3.2 years (forested). Greater MTTs were represented by more homogenous aqueous chemistry whereas smaller MTTs resulted in more dynamic compositions. The isotope and geochemical data presented provide a baseline for future hydrological modelling in the inland PNW.

  5. Water's Way at Sleepers River watershed – revisiting flow generation in a post-glacial landscape, Vermont USA

    USGS Publications Warehouse

    Shanley, James B.; Sebestyen, Stephen D.; McDonnell, Jeffrey J.; McGlynn, Brian L.; Dunne, Thomas

    2015-01-01

    The Sleepers River Research Watershed (SRRW) in Vermont, USA, has been the site of active hydrologic research since 1959 and was the setting where Dunne and Black demonstrated the importance and controls of saturation-excess overland flow (SOF) on streamflow generation. Here, we review the early studies from the SRRW and show how they guided our conceptual approach to hydrologic research at the SRRW during the most recent 25 years. In so doing, we chronicle a shift in the field from early studies that relied exclusively on hydrometric measurements to today's studies that include chemical and isotopic approaches to further elucidate streamflow generation mechanisms. Highlights of this evolution in hydrologic understanding include the following: (i) confirmation of the importance of SOF to streamflow generation, and at larger scales than first imagined; (ii) stored catchment water dominates stream response, except under unusual conditions such as deep frozen ground; (iii) hydrometric, chemical and isotopic approaches to hydrograph separation yield consistent and complementary results; (iv) nitrate and sulfate isotopic compositions specific to atmospheric inputs constrain new water contributions to streamflow; and (v) convergent areas, or ‘hillslope hollows’, contribute disproportionately to event hydrographs. We conclude by summarizing some remaining challenges that lead us to a vision for the future of research at the SRRW to address fundamental questions in the catchment sciences.

  6. USING HISTORICAL BIOLOGICAL DATA TO EVALUATE STATUS AND TRENDS IN THE BIG DARBY CREEK WATERSHED (OHIO, USA)

    EPA Science Inventory

    Assessment of watershed ecological status and trends is challenging for managers who lack randomly or consistently sampled data, or monitoring programs developed from a watershed perspective. This study investigated analytical approaches for assessment of status and trends using ...

  7. Diets of three species of anurans from the cache creek watershed, California, USA

    USGS Publications Warehouse

    Hothem, R.L.; Meckstroth, A.M.; Wegner, K.E.; Jennings, M.R.; Crayon, J.J.

    2009-01-01

    We evaluated the diets of three sympatric anuran species, the native Northern Pacific Treefrog, Pseudacris regilla, and Foothill Yellow-Legged Frog, Rana boylii, and the introduced American Bullfrog, Lithobates catesbeianus, based on stomach contents of frogs collected at 36 sites in 1997 and 1998. This investigation was part of a study of mercury bioaccumulation in the biota of the Cache Creek Watershed in north-central California, an area affected by mercury contamination from natural sources and abandoned mercury mines. We collected R. boylii at 22 sites, L. catesbeianus at 21 sites, and P. regilla at 13 sites. We collected both L. catesbeianus and R. boylii at nine sites and all three species at five sites. Pseudacris regilla had the least aquatic diet (100% of the samples had terrestrial prey vs. 5% with aquatic prey), followed by R. boylii (98% terrestrial, 28% aquatic), and L. catesbeianus, which had similar percentages of terrestrial (81%) and aquatic prey (74%). Observed predation by L. catesbeianus on R. boylii may indicate that interaction between these two species is significant. Based on their widespread abundance and their preference for aquatic foods, we suggest that, where present, L. catesbeianus should be the species of choice for all lethal biomonitoring of mercury in amphibians. Copyright ?? 2009 Society for the Study of Amphibians and Reptiles.

  8. Baseflow contribution to nitrate-nitrogen export from a large, agricultural watershed, USA

    NASA Astrophysics Data System (ADS)

    Schilling, Keith; Zhang, You-Kuan

    2004-08-01

    Nitrate-nitrogen export from the Raccoon River watershed in west-central Iowa is among the highest in the United State and contributes to impairment of downstream water quality. We examined a rare long-term record of streamflow and nitrate concentration data (1972-2000) to evaluate annual and seasonal patterns of nitrate losses in streamflow and baseflow from the Raccoon River. Combining hydrograph separation with a load estimation program, we estimated that baseflow contributes approximately two-thirds (17.3 kg/ha) of the mean annual nitrate export (26.1 kg/ha). Baseflow transport was greatest in spring and late fall when baseflow contributed more than 80% of the total export. Herein we propose a 'baseflow enrichment ratio' (BER) to describe the relation of baseflow water with baseflow nitrate loads. The long-term ratio of 1.23 for the Raccoon River suggests preferential leaching of nitrate to baseflow. Seasonal patterns of the BER identified the strong link between the baseflow nitrate loads and seasonal crop nitrogen requirements. Study results demonstrate the utility of assessing the baseflow contribution to nitrate loads to identify appropriate control strategies for reducing baseflow delivery of nitrate.

  9. Baseflow contribution to nitrate-nitrogen export from a large, agricultural watershed, USA

    USGS Publications Warehouse

    Schilling, K.; Zhang, Y.-K.

    2004-01-01

    Nitrate-nitrogen export from the Raccoon River watershed in west-central Iowa is among the highest in the United State and contributes to impairment of downstream water quality. We examined a rare long-term record of streamflow and nitrate concentration data (1972-2000) to evaluate annual and seasonal patterns of nitrate losses in streamflow and baseflow from the Raccoon River. Combining hydrograph separation with a load estimation program, we estimated that baseflow contributes approximately two-thirds (17.3 kg/ha) of the mean annual nitrate export (26.1 kg/ha). Baseflow transport was greatest in spring and late fall when baseflow contributed more than 80% of the total export. Herein we propose a 'baseflow enrichment ratio' (BER) to describe the relation of baseflow water with baseflow nitrate loads. The long-term ratio of 1.23 for the Raccoon River suggests preferential leaching of nitrate to baseflow. Seasonal patterns of the BER identified the strong link between the baseflow nitrate loads and seasonal crop nitrogen requirements. Study results demonstrate the utility of assessing the baseflow contribution to nitrate loads to identify appropriate control strategies for reducing baseflow delivery of nitrate. ?? 2004 Elsevier B.V. All rights reserved.

  10. Apparent 85Kr ages of groundwater within the Royal watershed, Maine, USA.

    PubMed

    Sidle, W C

    2006-01-01

    Specific 85Kr activity is mapped from 264 domestic and municipal wells sampled during 2002-2004 in the Royal watershed (361 km2), Maine. Gas samples are collected at 20 m, 40 m, and > 50 m interval depths within the unconfined aquifers. Gas extraction for 85Kr from wells is obtained directly via a wellhead methodology avoiding conventional collection of large sample volumes. Atmospheric 85Kr input to the recharge environment is estimated at 1.27 Bq m(-3) by time-series analyses of weighted monthly precipitation (2001-2004). Numerical simulation of Kr gas transport through the variable unsaturated zones to the water table suggests up to 12-year time lags locally, thus biasing the 85Kr groundwater ages. Apparent 85Kr ages suggest that approximately 70% of groundwater near 20 m depth was recharged less than 30 years BP (2004). Mass-age transport modeling suggests that post mid-1950s recharge penetrates to part of the basin's floor and that older groundwater seeps from the underlying fractured bedrock may occur.

  11. Inference of nitrogen cycling in three watersheds of northern Florida, USA, by multivariate statistical analysis

    SciTech Connect

    Fu, Ji-Meng; Winchester, J.W. )

    1994-03-01

    Nitrogen in fresh waters of three rivers in northern Florida-the Apalachicola-Chattahoochee-Flint (ACF) River system, Ochlockonee (Och), and Sopchoppy (Sop)- is inferred to be derived mostly from atmospheric deposition. Because the N:P mole ratios in the rivers are nearly three times higher than the Redfield ratio for aquatic photosynthesis, N is saturate in the ecosystems, not a limiting nutrient, although it may be chemically transformed. Absolute principal component analysis (APCA), a receptor model, was applied to many years of monitoring data for Apalachicola River water and rainfall over its basin in order to better understand aquatic chemistry of nitrogen in the watershed. The APCA model aged rain and groundwater. In the fresh rain component, the ratio of atmospheric nitrate to sulfate is close to that in rainwater, as if some samples had been collected following very recent rainfall. The aged rain component of the river water is distinguished by a low NO[sup [minus][sub 3

  12. Reproductive outcome and survival of common bottlenose dolphins sampled in Barataria Bay, Louisiana, USA, following the Deepwater Horizon oil spill

    PubMed Central

    Lane, Suzanne M.; Smith, Cynthia R.; Mitchell, Jason; Balmer, Brian C.; Barry, Kevin P.; McDonald, Trent; Mori, Chiharu S.; Rosel, Patricia E.; Rowles, Teresa K.; Speakman, Todd R.; Townsend, Forrest I.; Tumlin, Mandy C.; Wells, Randall S.; Zolman, Eric S.; Schwacke, Lori H.

    2015-01-01

    Common bottlenose dolphins (Tursiops truncatus) inhabit bays, sounds and estuaries across the Gulf of Mexico. Following the Deepwater Horizon oil spill, studies were initiated to assess potential effects on these ecologically important apex predators. A previous study reported disease conditions, including lung disease and impaired stress response, for 32 dolphins that were temporarily captured and given health assessments in Barataria Bay, Louisiana, USA. Ten of the sampled dolphins were determined to be pregnant, with expected due dates the following spring or summer. Here, we report findings after 47 months of follow-up monitoring of those sampled dolphins. Only 20% (95% CI: 2.50–55.6%) of the pregnant dolphins produced viable calves, as compared with a previously reported pregnancy success rate of 83% in a reference population. Fifty-seven per cent of pregnant females that did not successfully produce a calf had been previously diagnosed with moderate–severe lung disease. In addition, the estimated annual survival rate of the sampled cohort was low (86.8%, 95% CI: 80.0–92.7%) as compared with survival rates of 95.1% and 96.2% from two other previously studied bottlenose dolphin populations. Our findings confirm low reproductive success and high mortality in dolphins from a heavily oiled estuary when compared with other populations. Follow-up studies are needed to better understand the potential recovery of dolphins in Barataria Bay and, by extension, other Gulf coastal regions impacted by the spill. PMID:26538595

  13. Reproductive outcome and survival of common bottlenose dolphins sampled in Barataria Bay, Louisiana, USA, following the Deepwater Horizon oil spill.

    PubMed

    Lane, Suzanne M; Smith, Cynthia R; Mitchell, Jason; Balmer, Brian C; Barry, Kevin P; McDonald, Trent; Mori, Chiharu S; Rosel, Patricia E; Rowles, Teresa K; Speakman, Todd R; Townsend, Forrest I; Tumlin, Mandy C; Wells, Randall S; Zolman, Eric S; Schwacke, Lori H

    2015-11-07

    Common bottlenose dolphins (Tursiops truncatus) inhabit bays, sounds and estuaries across the Gulf of Mexico. Following the Deepwater Horizon oil spill, studies were initiated to assess potential effects on these ecologically important apex predators. A previous study reported disease conditions, including lung disease and impaired stress response, for 32 dolphins that were temporarily captured and given health assessments in Barataria Bay, Louisiana, USA. Ten of the sampled dolphins were determined to be pregnant, with expected due dates the following spring or summer. Here, we report findings after 47 months of follow-up monitoring of those sampled dolphins. Only 20% (95% CI: 2.50-55.6%) of the pregnant dolphins produced viable calves, as compared with a previously reported pregnancy success rate of 83% in a reference population. Fifty-seven per cent of pregnant females that did not successfully produce a calf had been previously diagnosed with moderate-severe lung disease. In addition, the estimated annual survival rate of the sampled cohort was low (86.8%, 95% CI: 80.0-92.7%) as compared with survival rates of 95.1% and 96.2% from two other previously studied bottlenose dolphin populations. Our findings confirm low reproductive success and high mortality in dolphins from a heavily oiled estuary when compared with other populations. Follow-up studies are needed to better understand the potential recovery of dolphins in Barataria Bay and, by extension, other Gulf coastal regions impacted by the spill.

  14. The areal extent of brown shrimp habitat suitability in Mobile Bay, Alabama, USA: Targeting vegetated habitat restoration

    USGS Publications Warehouse

    Smith, L.M.; Nestlerode, J.A.; Harwell, L.C.; Bourgeois, P.

    2010-01-01

    The availability of wetlands and shallow water habitats significantly influences Gulf of Mexico (GOM) penaeid shrimp fishery productivity. However, the GOM region has the highest rate of wetland loss in the USA. Protection and management of these vital GOM habitats are critical to sustainable shrimp fisheries. Brown shrimp (Farfantepenaeus aztecus) are a major component of GOM fisheries. We present an approach for estimating the areal extent of suitable habitat for post-larval and juvenile brown shrimp in Mobile Bay, Alabama, using an existing habitat suitability index model for the northern GOM calculated from probabilistic survey of water quality and sediment data, land cover data, and submerged aquatic vegetation coverages. This estuarine scale approach is intended to support targeted protection and restoration of these habitats. These analyses indicate that approximately 60% of the area of Mobile Bay is categorized as suitable to near optimal for post-larval and juvenile shrimp and 38% of the area is marginally to minimally suitable. We identify potential units within Mobile Bay for targeted restoration to improve habitat suitability. ?? 2010 Springer Science+Business Media B.V.

  15. Nutrient and suspended-sediment trends, loads, and yields and development of an indicator of streamwater quality at nontidal sites in the Chesapeake Bay watershed, 1985-2010

    USGS Publications Warehouse

    Langland, Michael; Blomquist, Joel; Moyer, Douglas; Hyer, Kenneth

    2012-01-01

    The U.S. Geological Survey (USGS) updates information on loads of, and trends in, nutrients and sediment annually to help the Chesapeake Bay Program (CBP) investigators assess progress toward improving water-quality conditions in the Chesapeake Bay and its watershed. CBP scientists and managers have worked since 1983 to improve water quality in the bay. In 2010, the U.S. Environmental Protection Agency (USEPA) established a Total Maximum Daily Load (TMDL) for the Chesapeake Bay. The TMDL specifies nutrient and sediment load allocations that need to be achieved in the watershed to improve dissolved oxygen, water-clarity, and chlorophyll conditions in the bay. The USEPA, USGS, and state and local jurisdictions in the watershed operate a CBP nontidal water-quality monitoring network and associated database that are used to update load and trend information to help assess progress toward reducing nutrient and sediment inputs to the bay. Data collected from the CBP nontidal network were used to estimate loads and trends for two time periods: a long-term period (1985-2010) at 31 "primary" sites (with storm sampling) and a 10-year period (2001-10) at 33 primary sites and 16 "secondary" sites (without storm sampling). In addition, loads at 64 primary sites were estimated for the period 2006 to 2010. Results indicate improving flow-adjusted trends for nitrogen and phosphorus for 1985 to 2010 at most of the sites in the network. For nitrogen, 21 of the 31 sites showed downward (improving) trends, whereas 2 sites showed upward (degrading) trends, and 8 sites showed no trends. The results for phosphorus were similar: 22 sites showed improving trends, 4 sites showed degrading trends, and 5 sites indicated no trends. For sediment, no trend was found at 40 percent of the sites, with 10 sites showing improving trends and 8 sites showing degrading trends. The USGS, working with CBP partners, developed a new water-quality indicator that combines the results of the 10-year trend

  16. Fresh Water Inflow and Oyster Productivity in Apalachicola Bay, FL (USA)

    EPA Science Inventory

    Apalachicola Bay lies at the mouth of the Apalachicola River, where seasonally variable freshwater inflows and shifting winds support an unusually productive and commercially important oyster fishery. While there is concern that upstream water withdrawals may impact the fishery,...

  17. ABUNDANCE AND DISTRIBUTION OF INDIGENOUS, NONINDIGENOUS, AND CRYPTOGENIC BENTHIC MACROFAUNA IN WILLAPA BAY, WASHINGTON, USA

    EPA Science Inventory

    Benthic macrofaunal samples were collected in Willapa Bay, WA, in four habitats [eelgrass (Zostera marina), Atlantic cordgrass (Spartina alterniflora), mud shrimp (Upogebia pugettensis), ghost shrimp (Neotrypaea californiensis)] in 1996 and in seven habitats (Zostera, Spartina, U...

  18. Guide to the littoral zone vascular flora of Carolina bay lakes (U.S.A.)

    PubMed Central

    Howell, Nathan; Braham, Richard R

    2016-01-01

    Abstract Background Carolina bays are elliptic, directionally aligned basins of disputed origin that occur on the Atlantic Coastal Plain from the Delmarva Peninsula to southern Georgia. In southeastern North Carolina, several large, natural, lacustrine systems (i.e., Carolina bay lakes) exist within the geomorphological features known as Carolina bays. Within the current distribution of Carolina bays, Bladen and Columbus counties (North Carolina) contain the only known examples of Carolina bay lakes. The Carolina bay lakes can be split into two major divisions, the “Bladen Lakes Group” which is characterized as being relatively unproductive (dystrophic – oligotrophic), and Lake Waccamaw, which stands alone in Columbus County and is known for its high productivity and species richness. Although there have been several studies conducted on these unique lentic systems, none have documented the flora comprehensively. New information Over the 2013−2014 growing seasons, the littoral zone flora of Carolina bay lakes was surveyed and vouchered. Literature reviews and herbarium crawls complemented this fieldwork to produce an inventory of the vascular plant species. This survey detected 205 taxa (species/subspecies and varieties) in 136 genera and 80 vascular plant families. Thirty-one species (15.2%) are of conservation concern. Lake Waccamaw exhibited the highest species richness with 145 catalogued taxa and 26 species of conservation concern. Across all sites, the Cyperaceae (25 spp.), Poaceae (21 spp.), Asteraceae (13 spp.), Ericaceae (8 spp.), Juncaceae (8 spp.), and Lentibulariaceae (6 spp.) were the six most species-rich vascular plant families encountered. A guide to the littoral zone flora of Carolina bay lakes is presented herein, including dichotomous keys, species accounts (including abundance, habitat, phenology, and exsiccatae), as well as images of living species and vouchered specimens. PMID:27350764

  19. Total Mercury and Methylmercury in the Great Egg Harbor River Watershed, New Jersey, USA

    NASA Astrophysics Data System (ADS)

    Barringer, J. L.; Riskin, M. L.; Szabo, Z.; Fischer, J. M.; Reilly, P. A.; Rosman, R.; Bonin, J. L.; Heckathorn, H. A.

    2007-12-01

    Hydrologic and biogeochemical conditions are important factors in the transport and distribution of mercury (Hg) in New Jersey Coastal Plain watersheds that contain extensive freshwater wetlands and where Hg bioaccumulation is of concern. U.S. Geological Survey studies found Hg concentrations in top predator fish from the Great Egg Harbor River mainstem that ranged from 2.9 to 4.5 mg/kg (dry wt.) and exceeded 10 ng/L in the watershed's acidic streams. An ongoing study with the N.J. Department of Environmental Protection indicates that atmospheric deposition of Hg to the wetlands and streams may be augmented by substantial contributions of Hg from ground water. Although background levels of Hg in water from the underlying aquifer typically are less than 10 ng/L, concentrations in water from more than 600 domestic wells in southern New Jersey have been shown to exceed the drinking-water maximum contaminant level of 2,000 ng/L. Therefore, to determine ground-water inputs to the streams, samples of ground water discharging to the tributaries and mainstem as well as streamwater samples collected during various flow conditions were analyzed for total Hg and methylmercury (MeHg). Total Hg concentrations in ground water discharging to the tributaries and mainstem were low to moderate (0.29-22 ng/L) in relatively undeveloped areas (including wetlands), but higher (36 and 177 ng/L) in two urban/suburban areas where much of the Hg was in particulate form. In recent and ongoing studies, total Hg concentrations in unfiltered samples of surface water, except those for one suburban tributary, have ranged from 2.13 to 37.7 ng/L. Concentrations in the suburban tributary have ranged from 50 ng/L during a dry period to 250 ng/L during a wet period. Hg concentrations in samples from a wetlands-embedded reach of the mainstem varied markedly with flow. In addition to increases in concentrations of total Hg, UV absorbance and concentrations of dissolved organic carbon also increased with

  20. Mercury and methylmercury dynamics in a coastal plain watershed, New Jersey, USA

    USGS Publications Warehouse

    Barringer, J.L.; Riskin, M.L.; Szabo, Z.; Reilly, P.A.; Rosman, R.; Bonin, J.L.; Fischer, J.M.; Heckathorn, H.A.

    2010-01-01

    The upper Great Egg Harbor River watershed in New Jersey's Coastal Plain is urbanized but extensive freshwater wetlands are present downstream. In 2006-2007, studies to assess levels of total mercury (THg) found concentrations in unfiltered streamwater to range as high as 187 ng/L in urbanized areas. THg concentrations were <20 ng/L in streamwater in forested/wetlands areas where both THg and dissolved organic carbon concentrations tended to increase while pH and concentrations of dissolved oxygen and nitrate decreased with flushing of soils after rain. Most of the river's flow comes from groundwater seepage; unfiltered groundwater samples contained up to 177 ng/L of THg in urban areas where there is a history of well water with THg that exceeds the drinking water standard (2,000 ng/L). THg concentrations were lower (<25 ng/L) in unfiltered groundwater from downstream wetland areas. In addition to higher THg concentrations (mostly particulate), concentrations of chloride were higher in streamwater and groundwater from urban areas than in those from downstream wetland areas. Methylmercury (MeHg) concentrations in unfiltered streamwater ranged from 0.17 ng/L at a forest/wetlands site to 2.94 ng/L at an urban site. The percentage of THg present as MeHg increased as the percentage of forest + wetlands increased, but also was high in some urban areas. MeHg was detected only in groundwater <1 m below the water/sediment interface. Atmospheric deposition is presumed to be the main source of Hg to the wetlands and also may be a source to groundwater, where wastewater inputs in urban areas are hypothesized to mobilize Hg deposited to soils. ?? 2010 US Government.

  1. Base flow nutrient discharges from lower delmarva peninsula watersheds of virginia, USA.

    PubMed

    Stanhope, Jennifer W; Anderson, Iris C; Reay, William G

    2009-01-01

    Proper management of shallow coastal systems, which are vulnerable to nutrient enrichment, requires knowledge of land use impacts on nutrient discharges. This study quantified base flow nutrient concentrations and yields for 1 yr (May 2001-April 2002) from 14 first-order streams on the Virginia Eastern Shore (VaES) on the Delmarva Peninsula and assessed their relationships with land cover and soil drainage class in their watersheds. Base flow water discharge rates (1.4-31.5 cm yr(-1)) were likely lower than the long-term average due to a severe drought. Seasonal mean nitrate concentrations were higher in winter, while mean dissolved organic carbon and ammonium concentrations were higher in summer. Annual base flow-weighted mean total dissolved nitrogen (TDN) concentrations were positively related to percent (%) agricultural land cover (r(2) = 0.43; p = 0.02) and % very poorly drained soils (r(2) = 0.51; p = 0.009) and negatively related to % forested land cover (r(2) = 0.54; p = 0.005). Patterns of base flow TDN yields were similar to those of concentrations but were also positively related to % developed land cover (r(2) = 0.40; p = 0.03). Agricultural and developed land covers, together with very poorly drained soil, accounted for 91% of the variability of TDN yields (p = 0.0001). Using a multiple regression model, the base flow TDN loading rate to a coastal lagoon on the VaES, a system vulnerable to nutrient enrichment, was estimated to be 28,170 kg N yr(-1).

  2. Potential pollutant sources in a Choptank River (USA) subwatershed and the influence of land use and watershed characteristics

    USGS Publications Warehouse

    Nino de Guzman, Gabriela T.; Hapeman, Cathleen J.; Prabhakara, Kusuma; Codling, Eton E.; Shelton, Daniel R.; Rice, Clifford P.; Hively, W. Dean; McCarty, Gregory W.; Lang, Megan W.; Torrents, Alba

    2012-01-01

    Row-crop and poultry production have been implicated as sources of water pollution along the Choptank River, an estuary and tributary of the Chesapeake Bay. This study examined the effects of land use, subwatershed characteristics, and climatic conditions on the water quality parameters of a subwatershed in the Choptank River watershed. The catchments within the subwatershed were defined using advanced remotely-sensed data and current geographic information system processing techniques. Water and sediment samples were collected in May–October 2009 and April–June 2010 under mostly baseflow conditions and analyzed for select bacteria, nitrate-N, ammonium-N, total arsenic, total phosphorus (TP), orthophosphate (ortho-P), and particle-phase phosphorus (PP); n = 96 for all analytes except for arsenic, n = 136, and for bacteria, n = 89 (aqueous) and 62 (sediment). Detections of Enterococci and Escherichia coli concentrations were ubiquitous in this subwatershed and showed no correlation to location or land use, however larger bacterial counts were observed shortly after precipitation. Nitrate-N concentrations were not correlated with agricultural lands, which may reflect the small change in percent agriculture and/or the similarity of agronomic practices and crops produced between catchments. Concentration data suggested that ammonia emission and possible deposition to surface waters occurred and that these processes may be influenced by local agronomic practices and climatic conditions. The negative correlation of PP and arsenic concentrations with percent forest was explained by the stronger signal of the head waters and overland flow of particulate phase analytes versus dissolved phase inputs from groundwater. Service roadways at some poultry production facilities were found to redirect runoff from the facilities to neighboring catchment areas, which affected water quality parameters. Results suggest that in this subwatershed, catchments with poultry production

  3. Use of estuarine water column tests for detecting toxic conditions in ambient areas of the Chesapeake Bay watershed

    SciTech Connect

    Hall, L.W. Jr.; Ziegenfuss, M.C.; Anderson, R.D.; Killen, W.D. Jr. )

    1995-02-01

    Various estuarine water column toxicity tests were conducted twice in nine different ambient stations in the Chesapeake Bay watershed over a 2-year period (1991 to 1993) to determine if toxic conditions existed. The following 8-d toxicity tests were conducted: larval sheepshead minnow (Cyprinodon variegatus) survival and growth test; larval grass shrimp (Palaemonetes pugio) survival and growth test; and a copepod (Eurytemora affinis) life-cycle test. During the second year of testing, two 48-h coot clam (Mulinia lateralis) tests were conducted at each station during each testing period. In 1991, the toxicity tests were conducted twice at stations in the Potomac River at Morgantown and Dahlgren, and in the Patapsco River and the Wye River at the Manor House. All of the above tests were conducted during the fall of 1992 and spring of 1993 at two stations in the Wye River, Nanticoke River, and Middle River. Inorganic contaminants, organic contaminants, and water-quality conditions were measured concurrently during the toxicity testing of ambient water. In 1991, reduced growth of sheepshead minnow larvae was reported at both Potomac River stations during the first test. Significant mortality of either the copepod or sheepshead minnow larvae was also reported at the Wye River during both tests. Results from the 1992/93 testing generally showed minimal effects for three of the test species at all stations. Reduced normal shell development was reported for the coot clam at both Middle River stations during the fall and spring tests concurrently with concentrations of various trace metals that exceeded chronic marine water-quality criteria.

  4. Comparison of recharge estimates at a small watershed in east-central Pennsylvania, USA

    USGS Publications Warehouse

    Risser, D.W.; Gburek, W.J.; Folmar, G.J.

    2009-01-01

    The common recommendation that recharge should be estimated from multiple methods is sound, but the inherent differences of the methods make it difficult to assess the accuracy of differing results. In this study, four methods for estimating groundwater recharge and two methods for estimating base flow (as a proxy for recharge) are compared at two hydrologic research sites in east-central Pennsylvania, USA. Results from the multiple methods all provided reasonable estimates of groundwater recharge that differed considerably. The estimates of mean annual recharge for the period 1994-2001 ranged from 22.9 to 35.7 cm - about 45% of the mean of all estimates. For individual years, recharge estimates from the multiple methods ranged from 30 to 42% of the mean value during the dry years and 64 to 76% of the mean value during wet years. Comparison of multiple methods was found to be useful for determining the range of plausible recharge rates and highlighting the uncertainty of the estimates. ?? US Government 2008.

  5. Phosphorus Geochemistry and Transport along Groundwater Flow paths at Five Agricultural Watersheds, USA

    NASA Astrophysics Data System (ADS)

    Domagalski, J. L.; Johnson, H. M.

    2009-12-01

    Phosphorus chemistry and transport were studied at five agricultural watersheds representing a range of climatic conditions and cropping patterns at five locations within the United States (California, Washington, Nebraska, Indiana, Maryland). Orchards and row crops were the dominant land use at the California and Washington locations, while corn and soybeans were the main crops at the remaining three. Irrigation was required at the California and Washington sites, while rain supplied most or all of the water needs at the remainder. Phosphorus concentrations were assessed within the unsaturated zone, along groundwater flow paths of approximately one kilometer in length and at various depths, and across the sediment water interface of receiving streams in small agricultural basins. Baseflow loadings of phosphorus to some of the streams accounted for up to 20% of the annual load in some locations. Unsaturated zone concentrations tended to be higher than groundwater concentrations because of recently applied fertilizer or manure and the rapid downward movement of irrigation or rainwater. Long residence times in groundwater appeared to result in conditions close to chemical equilibrium. In most cases, sorption onto hydrous iron oxides and differences in major element chemistry explained the variation in observed phosphorus concentrations within and between study units. Concentrations of hydrous iron oxides in the aquifer material also affected the saturation levels of sorbed phosphorus relative to the amount dissolved. Solution pH had a major impact at the location in Maryland. Changes in pH from approximately 7 in the unsaturated zone to less than 5 in groundwater resulted in complete sequestration of phosphorus and under-saturation of the iron oxides along the flow path. Low iron oxide concentrations in the unsaturated zone and the aquifer resulted in uniformly higher concentrations at the Nebraska location. High loadings of phosphorus at an orchard in California

  6. Management case study: Tampa Bay, Florida

    USGS Publications Warehouse

    Morrison, G.; Greening, H.S.; Yates, K.K.

    2012-01-01

    Tampa Bay, Florida,USA, is a shallow,subtropical estuary that experienced severe cultural eutrophication between the 1940s and 1980s, a period when the human population of its watershed quadrupled. In response, citizen action led to the formation of a public- and private-sector partnership (the Tampa Bay Estuary Program), which adopted a number of management objectives to support the restoration and protection of the bay’s living resources. These included numeric chlorophyll a and water-clarity targets, as well as long-term goals addressing the spatial extent of sea grasses and other selected habitat types, to support estuarine-dependent faunal guilds.

  7. Chesapeake Bay TMDL

    EPA Pesticide Factsheets

    In 2010 EPA established the Chesapeake Bay TMDL, a comprehensive pollution diet with accountability measures to restore clean water in the bay and local waters. It set limits for nutrients and sediment to meet water quality standards across the watershed

  8. A SIMPLIFIED MODELING OF FLUSHING AND RESIDENCE TIME IN 42 EMBAYMENTS IN NEW ENGLAND, USA, WITH SPECIAL ATTENTION TO GRENWICH BAY, RHODE ISLAND

    EPA Science Inventory

    A simplified protocol has been developed to meet the need for modeling hydrodynamics and transport in large numbers of embayments quickly and reliably. The procedure is illustrated with 42 embayments in southern New England, USA, giving special attention to Greenwich Bay, RI. The...

  9. Passive Sampling Provides Evidence for Neward Bay as a Source of Polychlorinated Dibenzo-p-Dioxins and Furans to the New York/New Jersey, USA, Atmosphere

    EPA Science Inventory

    Freely dissolved and gas phase polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were measured in the water column and atmosphere at five locations within Newark Bay (New Jersey, USA) from May 2008 to August 2009 with polyethylene (PE) passive ...

  10. Soil bacterial communities of a calcium-supplemented and a reference watershed at the Hubbard Brook Experimental Forest (HBEF), New Hampshire, USA.

    PubMed

    Sridevi, Ganapathi; Minocha, Rakesh; Turlapati, Swathi A; Goldfarb, Katherine C; Brodie, Eoin L; Tisa, Louis S; Minocha, Subhash C

    2012-03-01

    Soil Ca depletion because of acidic deposition-related soil chemistry changes has led to the decline of forest productivity and carbon sequestration in the northeastern USA. In 1999, acidic watershed (WS) 1 at the Hubbard Brook Experimental Forest (HBEF), NH, USA was amended with Ca silicate to restore soil Ca pools. In 2006, soil samples were collected from the Ca-amended (WS1) and reference watershed (WS3) for comparison of bacterial community composition between the two watersheds. The sites were about 125 m apart and were known to have similar stream chemistry and tree populations before Ca amendment. Ca-amended soil had higher Ca and P, and lower Al and acidity as compared with the reference soils. Analysis of bacterial populations by PhyloChip revealed that the bacterial community structure in the Ca-amended and the reference soils was significantly different and that the differences were more pronounced in the mineral soils. Overall, the relative abundance of 300 taxa was significantly affected. Numbers of detectable taxa in families such as Acidobacteriaceae, Comamonadaceae, and Pseudomonadaceae were lower in the Ca-amended soils, while Flavobacteriaceae and Geobacteraceae were higher. The other functionally important groups, e.g. ammonia-oxidizing Nitrosomonadaceae, had lower numbers of taxa in the Ca-amended organic soil but higher in the mineral soil.

  11. Multimedia screening of contaminants of emerging concern (CECS) in coastal urban watersheds in southern California (USA).

    PubMed

    Maruya, Keith A; Dodder, Nathan G; Sengupta, Ashmita; Smith, Deborah J; Lyons, J Michael; Heil, Ann T; Drewes, Jörg E

    2016-08-01

    To examine the occurrence and fate of contaminants of emerging concern (CECs) and inform future monitoring of CECs in coastal urban waterways, water, sediment, and fish tissue samples were collected and analyzed for a broad suite of pharmaceuticals and personal care products (PPCPs), commercial and/or household chemicals, current use pesticides, and hormones in an effluent-dominated river and multiple embayments in southern California (USA). In the Santa Clara River, which receives treated wastewater from several facilities, aqueous phase CECs were detectable at stations nearest discharges from municipal wastewater treatment plants but were attenuated downstream. Sucralose and the chlorinated phosphate flame retardants tris(1-chloro-2-propyl) phosphate (TCPP), tris(1,3-dichloro-2-propyl) phosphate (TDCPP), and tris(2-chloroethyl) phosphate (TCEP) were most abundant in water, with maximum concentrations of 35 μg/L, 3.3 μg/L, 1.4 μg/L, and 0.81 μg/L, respectively. Triclocarban, an antimicrobial agent in use for decades, was more prevalent in water than triclosan or nonylphenol. Maximum concentrations of bifenthrin, permethrin, polybrominated diphenyl ethers (PBDEs), and degradates of fipronil exceeded CEC-specific monitoring trigger levels recently established for freshwater and estuarine sediments by factors of 10 to 1000, respectively. Maximum fish tissue concentrations of PBDEs varied widely (370 ng/g and 7.0 ng/g for the Santa Clara River and coastal embayments, respectively), with most species exhibiting concentrations at the lower end of this range. These results suggest that continued monitoring of pyrethroids, PBDEs, and degradates of fipronil in sediment is warranted in these systems. In contrast, aqueous pharmaceutical concentrations in the Santa Clara River were not close to exceeding current monitoring trigger levels, suggesting a lower priority for targeted monitoring in this medium. Environ Toxicol Chem 2016;35:1986-1994. © 2016 SETAC.

  12. Total nutrient and sediment loads, trends, yields, and nontidal water-quality indicators for selected nontidal stations, Chesapeake Bay Watershed, 1985–2011

    USGS Publications Warehouse

    Langland, Michael J.; Blomquist, Joel D.; Moyer, Douglas; Hyer, Kenneth; Chanat, Jeffrey G.

    2013-01-01

    The U.S. Geological Survey, in cooperation with Chesapeake Bay Program (CBP) partners, routinely reports long-term concentration trends and monthly and annual constituent loads for stream water-quality monitoring stations across the Chesapeake Bay watershed. This report documents flow-adjusted trends in sediment and total nitrogen and phosphorus concentrations for 31 stations in the years 1985–2011 and for 32 stations in the years 2002–2011. Sediment and total nitrogen and phosphorus yields for 65 stations are presented for the years 2006–2011. A combined nontidal water-quality indicator (based on both trends and yields) indicates there are more stations classified as “improving water-quality trend and a low yield” than “degrading water-quality trend and a high yield” for total nitrogen. The same type of 2-way classification for total phosphorus and sediment results in equal numbers of stations in each indicator class.

  13. Spatial analysis of land use and shallow groundwater vulnerability in the watershed adjacent to Assateague Island National Seashore, Maryland and Virginia, USA

    USGS Publications Warehouse

    LaMotte, A.E.; Greene, E.A.

    2007-01-01

    Spatial relations between land use and groundwater quality in the watershed adjacent to Assateague Island National Seashore, Maryland and Virginia, USA were analyzed by the use of two spatial models. One model used a logit analysis and the other was based on geostatistics. The models were developed and compared on the basis of existing concentrations of nitrate as nitrogen in samples from 529 domestic wells. The models were applied to produce spatial probability maps that show areas in the watershed where concentrations of nitrate in groundwater are likely to exceed a predetermined management threshold value. Maps of the watershed generated by logistic regression and probability kriging analysis showing where the probability of nitrate concentrations would exceed 3 mg/L (>0.50) compared favorably. Logistic regression was less dependent on the spatial distribution of sampled wells, and identified an additional high probability area within the watershed that was missed by probability kriging. The spatial probability maps could be used to determine the natural or anthropogenic factors that best explain the occurrence and distribution of elevated concentrations of nitrate (or other constituents) in shallow groundwater. This information can be used by local land-use planners, ecologists, and managers to protect water supplies and identify land-use planning solutions and monitoring programs in vulnerable areas. ?? 2006 Springer-Verlag.

  14. Reproduction and environmental contamination in tree swallows nesting in the Fox River drainage and Green Bay, Wisconsin, USA

    SciTech Connect

    Custer, C.M.; Custer, T.W.; Allen, P.D.; Stromborg, K.L.; Melancon, M.J.

    1998-09-01

    Concentration, accumulation, and effects of polychlorinated biphenyls (PCBs) on reproduction in tree swallows (Tachycineta bicolor) were studied at four sites in the Fox River drainage and in Green Bay, Lake Michigan, Wisconsin, USA, in 1994 and 1995. Total PCBs in eggs and newly hatched young and 12-d-old nestlings at two contaminated sites (Kidney Island and Arrowhead) were higher than concentrations at two reference sites. Concentrations of 11 PCB congeners were also higher at contaminated compared to reference sites. Polychlorinated biphenyls (PCBs) accumulated in nestlings at a higher rate at contaminated sites compared to reference locations. Dichlorodiphenyldichloroethylene (DDE) was the only other organochlorine found in all samples; concentrations for all samples averaged {le}0.20 {micro}g/g wet weight. Total PCBs and p,p{prime}-DDE concentrations did not differ among clutches where all eggs hatched, some eggs hatched, and no eggs hatched.

  15. EFFECTS OF HURRICANE IVAN ON WATER QUALITY IN PENSACOLA BAY, FL USA

    EPA Science Inventory

    Pensacola Bay was in the strong NE quadrant of Hurricane Ivan when it made landfall on September 16, 2004 as a category 3 hurricane on the Saffir-Simpson scale. We present data describing the timeline and maximum height of the storm surge, the extent of flooding of coastal land, ...

  16. BENTHIC MACROALGAE, DISSOLVED SULFIDES, AND AMPHIPODS IN SURFICIAL SEDIMENTS OF YAQUINA BAY ESTUARY, OREGON, USA

    EPA Science Inventory

    Surveys of benthic green macroalgae at two sites in Yaquina Bay Estuary, Oregon, in 1999 showed that percent cover and biomass values in June were much higher at one site, Idaho Point, than at the other site, Coquille Point. The frequency of detectable hydrogen sulfide odor late...

  17. MODELING FISH AND SHELLFISH DISTRIBUTIONS IN THE MOBILE BAY ESTUARY, USA

    EPA Science Inventory

    Estuaries in the Gulf of Mexico provide rich habitat for many fish and shellfish, including those that have been identified as economically and ecologically important. For the Mobile Bay estuary, we developed statistical models to relate distributions of individual species and sp...

  18. Hydrodynamic modeling and ecohydrological analysis of river inflow effects on Apalachicola Bay, Florida, USA

    NASA Astrophysics Data System (ADS)

    Huang, Wenrui

    2010-02-01

    This paper presents an integrated hydrodynamic modeling and probability analysis approach to assess the long-term effects of changing river inflows on the estuarine ecosystem. The probability analysis method, which is popularly used in advanced hydrological frequency analysis of river flows and rainfalls, has been applied to analyze the effects of changing inflow on salinity and thus on oyster ecology in Apalachicola Bay. Long-term salinity data were predicted through the application of a calibrated 3D hydrodynamic model under two river inflow conditions over a 10-year period. The first flow represents the historic flow. The 2nd flow condition, called Scenario-1, represents a regulated flow scenario to account for the potential increasing upstream water demands. Two stations, Mid Bay and Dry Bar, in the bay were selected to examine the estuarine responses. Under the historic flow condition, the maximum probability salinity at Dry Bar in the rich oyster reef is near 24 ppt, within the optimal salinity range for oyster growth of 16-26 ppt (Harned et al., 1996); the maximum probability salinity at Mid Bay station is 27 ppt, beyond the optimal salinity for oyster growth in mid-bay area where there is no oyster reef around. While it is difficult to examine the difference between two scenarios by conventional time series analysis of river flows and salinity, probability analysis reasonably characterizes and quantifies the changes of river flow and salinity patterns over the 10-year period. The Scenario-1 has caused the increase of the probability in low flows. Higher probability of low flows for the regulated flow scenario shortens the period of optimal salinity in the oyster reef, and cause substantial increase of exceedance probability of higher salinity in the oyster reef to the level beyond the optimal salinity range for oyster growth. The probability analysis approach has demonstrated its advantage for the risk assessments of the long-term estuarine ecohydrological

  19. The Effect of Coastal Development on Storm Surge Flooding in Biscayne Bay, Florida, USA (Invited)

    NASA Astrophysics Data System (ADS)

    Zhang, K.; Liu, H.; Li, Y.

    2013-12-01

    Barrier islands and associated bays along the Atlantic and Gulf Coasts are a favorite place for both living and visiting. Many of them are vulnerable to storm surge flooding because of low elevations and constantly being subjected to the impacts of storms. The population increase and urban development along the barrier coast have altered the shoreline configuration, resulting in a dramatic change in the coastal flooding pattern in some areas. Here we present such a case based on numerical simulations of storm surge flooding caused by the1926 hurricane in the densely populated area surrounding Biscayne Bay in Miami, Florida. The construction of harbor and navigation channels, and the development of real estate and the roads connecting islands along Biscayne Bay have changed the geometry of Biscayne Bay since 1910s. Storm surge simulations show that the Port of Miami and Dodge Island constructed by human after 1950 play an important role in changing storm surge inundation pattern along Biscayne Bay. Dodge Island enhances storm surge and increases inundation in the area south of the island, especially at the mouth of Miami River (Downtown of Miami), and reduces storm surge flooding in the area north of the island, especially in Miami Beach. If the Hurricane Miami of 1926 happened today, the flooding area would be reduced by 55% and 20% in the Miami Beach and North Miami areas, respectively. Consequently, it would prevent 400 million of property and 10 thousand people from surge flooding according to 2010 U.S census and 2007 property tax data. Meanwhile, storm water would penetrate further inland south of Dodge Island and increase the flooding area by 25% in the Miami River and Downtown Miami areas. As a result, 200 million of property and five thousand people would be impacted by storm surge.

  20. Ploidy Distribution of the Harmful Bloom Forming Macroalgae Ulva spp. in Narragansett Bay, Rhode Island, USA, Using Flow Cytometry Methods.

    PubMed

    Potter, Elaine E; Thornber, Carol S; Swanson, John-David; McFarland, Malcolm

    2016-01-01

    Macroalgal blooms occur worldwide and have the potential to cause severe ecological and economic damage. Narragansett Bay, RI is a eutrophic system that experiences summer macroalgal blooms composed mostly of Ulva compressa and Ulva rigida, which have biphasic life cycles with separate haploid and diploid phases. In this study, we used flow cytometry to assess ploidy levels of U. compressa and U. rigida populations from five sites in Narragansett Bay, RI, USA, to assess the relative contribution of both phases to bloom formation. Both haploid gametophytes and diploid sporophytes were present for both species. Sites ranged from a relative overabundance of gametophytes to a relative overabundance of sporophytes, compared to the null model prediction of √2 gametophytes: 1 sporophyte. We found significant differences in cell area between ploidy levels for each species, with sporophyte cells significantly larger than gametophyte cells in U. compressa and U. rigida. We found no differences in relative growth rate between ploidy levels for each species. Our results indicate the presence of both phases of each of the two dominant bloom forming species throughout the bloom season, and represent one of the first studies of in situ Ulva life cycle dynamics.

  1. Ecological periodic tables for benthic macrofaunal usage of estuarine habitats: Insights from a case study in Tillamook Bay, Oregon, USA

    NASA Astrophysics Data System (ADS)

    Ferraro, Steven P.; Cole, Faith A.

    2012-05-01

    This study validates the ecological relevance of estuarine habitat types to the benthic macrofaunal community and, together with previous similar studies, suggests they can serve as elements in ecological periodic tables of benthic macrofaunal usage in the bioregion. We compared benthic macrofaunal Bray-Curtis similarity and the means of eight benthic macrofaunal community measures across seven habitat types in Tillamook Bay, Oregon, USA: intertidal eelgrass (Zostera marina), dwarf eelgrass (Zostera japonica), oyster (Crassostrea gigas) ground culture, burrowing mud shrimp (Upogebia pugettensis), burrowing ghost shrimp (Neotrypaea californiensis), sand and subtidal. Benthic macrofaunal Bray-Curtis similarity differed among all the habitats except ghost shrimp and sand. The habitat rank order on mean benthic macrofaunal species richness, abundance and biomass was dwarf eelgrass ≈ oyster ≥ mud shrimp ≈ eelgrass > sand ≈ ghost shrimp ≈ subtidal. The benthic macrofaunal habitat usage pattern in Tillamook Bay was, with a few exceptions, similar to that in two other US Pacific Northwest estuaries. The exceptions indicate variants of eelgrass and ghost shrimp habitat that differ in benthic macrofaunal usage perhaps due to differences in the coarseness of the sand fraction of the sediments in which they live. The similarities indicate periodic benthic macrofaunal usage patterns across the other habitat types extend over a wider geographic scale and range of environmental conditions than previously known.

  2. Diets and trophic-guild structure of a diverse fish assemblage in Chesapeake Bay, U.S.A.

    PubMed

    Buchheister, A; Latour, R J

    2015-03-01

    Dietary habits and trophic-guild structure were examined in a fish assemblage (47 species) of the Chesapeake Bay estuary, U.S.A., using 10 years of data from >25 000 fish stomachs. The assemblage was comprised of 10 statistically significant trophic guilds that were principally differentiated by the relative amounts of Mysida, Bivalvia, Polychaeta, Teleostei and other Crustacea in the diets. These guilds were broadly aggregated into five trophic categories: piscivores, zooplanktivores, benthivores, crustacivores and miscellaneous consumers. Food web structure was largely dictated by gradients in habitat (benthic to pelagic) and prey size. Size classes within piscivorous species were more likely to be classified into different guilds, reflecting stronger dietary changes through ontogeny relative to benthivores and other guilds. Relative to predator species and predator size, the month of sampling had negligible effects on dietary differences within the assemblage. A majority of sampled fishes derived most of their nutrition from non-pelagic prey sources, suggesting a strong coupling of fish production to benthic and demersal food resources. Mysida (predominantly the opossum shrimp Neomysis americana) contributed substantially to the diets of over 25% of the sampled predator groups, indicating that this species is a critical, but underappreciated, node in the Chesapeake Bay food web.

  3. Behaviour of wintering Tundra Swans Cygnus columbianus columbianus at the Eel River delta and Humboldt Bay, California, USA

    USGS Publications Warehouse

    Black, Jeffrey M.; Gress, Carol; Byers, Jacob W.; Jennings, Emily; Ely, Craig

    2010-01-01

    Tundra Swan Cygnus columbianus columbinanus phenology and behaviour at the Eel River delta and southern Humboldt Bay in northern California, USA, is described. Counts made each January from 1963 onwards peaked at 1,502 swans in 1988. Monthly counts recorded during the 2006/07 and 2008/09 winters peaked in February, at 1,033 and 772 swans respectively. Swans roosted on ephemeral ponds at the Humboldt Bay National Wildlife Refuge, on ephemeral ponds within grassland pastures in the vicinity of the Refuge, and perhaps also used the Eel River as a roost. Flights between Refuge roosts and the pastures and ponds occurred in the two hours after sunrise and before dark. In winters 2008/09 and 2009/10, the percentage of cygnets in the flocks was 10.6% and 21.4% respectively, and increased to =31% cygnets each year after most swans had departed from the area in March. Average brood size in 2009/10 was 2.1 cygnets. Daily activities consisted of foraging (44.9% of activities recorded), comfort behaviour (22.1%), locomotion (16.2%) and vigilance (15.5%). Eight neck-collared swans identified in the wintering flock were marked at four locations in different parts of Alaska, up to 1,300 km apart.

  4. Ploidy Distribution of the Harmful Bloom Forming Macroalgae Ulva spp. in Narragansett Bay, Rhode Island, USA, Using Flow Cytometry Methods

    PubMed Central

    Swanson, John-David; McFarland, Malcolm

    2016-01-01

    Macroalgal blooms occur worldwide and have the potential to cause severe ecological and economic damage. Narragansett Bay, RI is a eutrophic system that experiences summer macroalgal blooms composed mostly of Ulva compressa and Ulva rigida, which have biphasic life cycles with separate haploid and diploid phases. In this study, we used flow cytometry to assess ploidy levels of U. compressa and U. rigida populations from five sites in Narragansett Bay, RI, USA, to assess the relative contribution of both phases to bloom formation. Both haploid gametophytes and diploid sporophytes were present for both species. Sites ranged from a relative overabundance of gametophytes to a relative overabundance of sporophytes, compared to the null model prediction of √2 gametophytes: 1 sporophyte. We found significant differences in cell area between ploidy levels for each species, with sporophyte cells significantly larger than gametophyte cells in U. compressa and U. rigida. We found no differences in relative growth rate between ploidy levels for each species. Our results indicate the presence of both phases of each of the two dominant bloom forming species throughout the bloom season, and represent one of the first studies of in situ Ulva life cycle dynamics. PMID:26918869

  5. Relationship between lysosomal membrane destabilization and chemical body burden in eastern oysters (Crassostrea virginica) from Galveston Bay, Texas, USA.

    PubMed

    Hwang, Hyun-Min; Wade, Terry L; Sericano, Jose L

    2002-06-01

    Lysosomal destabilization was measured by using hemocytes of eastern oysters (Crassostrea virginica) collected along a chemical concentration gradient in Galveston Bay, Texas, USA. Results of the lysosomal response were compared to concentrations of organic compounds and trace elements in oyster tissue. Concentrations (on a dry-wt basis) ranged from 288 to 2,390 ng/g for polycyclic aromatic hydrocarbons (PAHs), 38 to 877 ng Sn/g for tri-n-butyltin (TBT), 60 to 562 ng/g for polyclorinated biphenyls (PCBs), and 7 to 71 ng/g for total DDT. Trace element concentrations (on a dry-wt basis) ranged from 1.1 to 4.0 microg/g for Cd, 105 to 229 microg/g for Cu, 212 to 868 microg/g for Al, and 1,200 to 8,180 microg/g for Zn. The percentage of destabilized lysosomes ranged from 34 to 81%. A significant positive correlation (p < 0.05) was observed between lysosomal destabilization and body burden of organic compounds (PAHs, PCBs, TBT, and chlorinated pesticides). No significant correlation was found between metal concentrations and lysosomal destabilization. Based on lysosomal destabilization, the study sites in Galveston Bay can be placed in one of three groups: healthy (Hanna Reef and Confederate Bay), moderately damaged (Offats Bayou and Todd's Dump), and highly damaged (Yacht Club and Ship Channel). Lysosomal destabilization that is consistent with toxic chemical body burdens supports previous observations that lysosomal membranes are damaged by toxic chemicals and indicates that this method can serve as an early screening tool to assess overall ecosystem health by using oysters.

  6. Concentrations, loads, and yields of total nitrogen and total phosphorus in the Barnegat Bay-Little Egg Harbor watershed, New Jersey, 1989-2011, at multiple spatial scales

    USGS Publications Warehouse

    Baker, Ronald J.; Wieben, Christine M.; Lathrop, Richard G.; Nicholson, Robert S.

    2014-01-01

    Concentrations, loads, and yields of nutrients (total nitrogen and total phosphorus) were calculated for the Barnegat Bay-Little Egg Harbor (BB-LEH) watershed for 1989–2011 at annual and seasonal (growing and nongrowing) time scales. Concentrations, loads, and yields were calculated at three spatial scales: for each of the 81 subbasins specified by 14-digit hydrologic unit codes (HUC-14s); for each of the three BB-LEH watershed segments, which coincide with segmentation of the BB-LEH estuary; and for the entire BB-LEH watershed. Base-flow and runoff values were calculated separately and were combined to provide total values. Available surface-water-quality data for all streams in the BB-LEH watershed for 1980–2011 were compiled from existing datasets and quality assured. Precipitation and streamflow data were used to distinguish between water-quality samples that were collected during base-flow conditions and those that were collected during runoff conditions. Base-flow separation of hydrographs of six streams in the BB-LEH watershed indicated that base flow accounts for about 72 to 94 percent of total flow in streams in the watershed. Base-flow mean concentrations (BMCs) of total nitrogen (TN) and total phosphorus (TP) for each HUC-14 subbasin were calculated from relations between land use and measured base-flow concentrations. These relations were developed from multiple linear regression models determined from water-quality data collected at sampling stations in the BB-LEH watershed under base-flow conditions and land-use percentages in the contributing drainage basins. The total watershed base-flow volume was estimated for each year and season from continuous streamflow records for 1989–2011 and relations between precipitation and streamflow during base-flow conditions. For each year and season, the base-flow load and yield were then calculated for each HUC-14 subbasin from the BMCs, total base-flow volume, and drainage area. The watershed

  7. A simple index explains annual atrazine transport from surface runoff-prone watersheds in the north-central USA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Detecting water quality effects of conservation practices at a watershed scale is complicated. Beneficial management practices may be very effective at the edge of a field, but their effect is often very difficult to detect at the watershed scale. Further, effectiveness of the practice itself often ...

  8. Long-term suspended sediment transport in the Goodwater Creek Experimental Watershed and Salt River Basin, Missouri, USA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Since 1992, efforts have been conducted in Goodwater Creek Experimental Watershed to assess sediment transport from this 72-km2 Missouri watershed located in the Salt River Basin, the Long-Term Agro-ecosystem Research site in the Central Mississippi River Basin. This effort was complemented by field...

  9. Water quality in the Fort Cobb watershed, USA: spatial and temporal patters of sediment concentration in streams

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Agricultural watersheds often exhibit impaired water quality due to sediment, nutrients, and associated contaminants. It is difficult to extend field-scale knowledge about agricultural impacts on water quality to watershed-scale because of many complex interactions within the landscape. This resea...

  10. The importance of small urbanized watersheds to pollutant loading in a large oligotrophic subalpine lake of the western USA.

    PubMed

    Rios, David T; Chandra, Sudeep; Heyvaert, Alan C

    2014-11-01

    Urban land use has been implicated as a major contributor of nonpoint source pollution in aquatic systems. Through increased nonpoint delivery of pollutants, including constituents found in stormwater, Lake Tahoe is undergoing a marked decline in its transparency, primarily due to increasing production of algae from enhanced nutrient loading and delivery of fine particles to the lake from the watershed. In response to these findings, a regional restoration effort is underway to improve basin watersheds and the water quality in Lake Tahoe. In this study, stormwater autosamplers were used to collect flow-weighted composite samples that characterized event mean concentrations for event and nonevent conditions within a small, urbanized watershed in the Tahoe basin. An event-specified constant-concentration water quality model was then applied to the event mean concentration and continuous streamflow data to estimate pollutant loads for nitrate, nitrite, ammonia, orthophosphate, and suspended sediment. These data were compared with previously reported load estimates from 10 primary monitored streams in larger watersheds of the Tahoe basin. Results from a linear regression analysis demonstrate strong and significant relationships between watershed impervious area and pollutant loadings from Lake Tahoe watersheds. These small, urbanized watersheds and intervening zones, which only comprise 10 % of the total Lake Tahoe drainage area, include a significant portion of the total Lake Tahoe impervious area. The findings of this study suggest that small, urbanized watersheds and intervening zones are disproportionately important contributors of nonpoint source pollution, including nutrients and suspended particles.

  11. Organic Composition of Size-Segregated Aerosols Sampled During the 2002 Bay Regional Atmospheric Chemistry Experiment (BRACE), Florida, USA

    NASA Astrophysics Data System (ADS)

    Tremblay, R. T.; Zika, R. G.

    2003-04-01

    Aerosol samples were collected for the analysis of organic source markers using non-rotating Micro Orifice Uniform Deposit Impactors (MOUDI) as part of the Bay Regional Atmospheric Chemistry Experiment (BRACE) in Tampa, FL, USA. Daily samples were collected 12 m above ground at a flow rate of 30 lpm throughout the month of May 2002. Aluminum foil discs were used to sample aerosol size fractions with aerodynamic cut diameter of 18, 10, 5.6, 3.2, 1.8, 1.0, 0.56, 0.32, 0.17 and 0.093 um. Samples were solvent extracted using a mixture of dichloromethane/acetone/hexane, concentrated and then analyzed using gas chromatography-mass spectrometry (GC/MS). Low detection limits were achieved using a HP Programmable Temperature Vaporizing inlet (PTV) and large volume injections (80ul). Excellent chromatographic resolution was obtained using a 60 m long RTX-5MS, 0.25 mm I.D. column. A quantification method was built for over 90 organic compounds chosen as source markers including straight/iso/anteiso alkanes and polycyclic aromatic hydrocarbons (PAH). The investigation of potential aerosol sources for different particle sizes using known organic markers and source profiles will be presented. Size distributions of carbon preference indices (CPI), percent wax n-alkanes (%WNA) and concentration of selected compounds will be discussed. Also, results will be compared with samples acquired in different environments including the 1999 Atlanta SuperSite Experiment, GA, USA.

  12. Selenium dynamics in Farmington Bay wetlands, Great Salt Lake, Salt Lake City, Utah, USA.

    NASA Astrophysics Data System (ADS)

    Dicataldo, G.; Hayes, D. F.; Miller, T. G.; Chaudhuri, S.

    2006-12-01

    The dynamics of Selenium (Se) and other water quality parameters in the Farmington Bay wetlands were presented. This is the first time that the fate and transport of selenium is being studied in Farmington Bay wetlands. The significant salinity gradient between wetland impoundments and the hypersaline condition of the Great Salt Lake (GSL) make these wetlands systems unique. Selenium has been observed for the first time to cycle diurnally. A 100% increase of total selenium was measured during a 24-hour study in October 2005 at site #5320 at nighttime (i.e., 1.99 micrograms/L at 3:00 a.m. MST) compared to daytime (i.e., 0.99 micrograms/L at 2:00 p.m. MST). Particulate selenium also increased at the same site during nighttime and decreased during daylight. No significant daily changes were measured in dissolved selenium concentrations between day and night. Total suspended solids (TSS) measured during the same time period increased to a maximum concentration of 107 mg/L (at 4:21 a.m. MST) during nighttime and dramatically decreased after sunrise (i.e., 18.8 mg/L at 8:21 a.m. MST). Particulate generation at night could be linked to total and particulate selenium increase during this time period. Later studies in May 2006 have shown that total organic carbon (TOC) increased about 3.5-folds (i.e., from 2.9 mg/L to 12.9 mg/L) during nighttime (with high peak at 4:00 a.m. MST) and decreased dramatically at sunrise (about 6:30 a.m. MST) in May 2006. Seasonal selenium speciation showed for the first time that the predominant species reaching the Farmington Bay are elemental selenium and selenide species (organic and inorganic) (Se(0) + Se(-2)). This is a significant finding toward a better understand of the bioavailability of selenium to birds and aquatic life in Farmington Bay. The selenium concentration as water parcels moved through the system showed to be reduced up to 186%. Also, average monthly loads of selenium to Farmington Bay from Ambassador Duck Club wetlands

  13. Preliminary estimates of residence times and apparent ages of ground water in the Chesapeake Bay watershed, and water-quality data from a survey of springs

    USGS Publications Warehouse

    Focazio, Michael J.; Plummer, L. Neil; Bohlke, John K.; Busenberg, Eurybiades; Bachman, L. Joseph; Powars, David S.

    1998-01-01

    Knowledge of the residence times of the ground-water systems in Chesapeake Bay watershed helps resource managers anticipate potential delays between implementation of land-management practices and any improve-ments in river and estuary water quality. This report presents preliminary estimates of ground-water residence times and apparent ages of water in the shallow aquifers of the Chesapeake Bay watershed. A simple reservoir model, published data, and analyses of spring water were used to estimate residence times and apparent ages of ground-water discharge. Ranges of aquifer hydraulic characteristics throughout the Bay watershed were derived from published literature and were used to estimate ground-water residence times on the basis of a simple reservoir model. Simple combinations of rock type and physiographic province were used to delineate hydrogeomorphic regions (HGMR?s) for the study area. The HGMR?s are used to facilitate organization and display of the data and analyses. Illustrations depicting the relation of aquifer characteristics and associated residence times as a continuum for each HGMR were developed. In this way, the natural variation of aquifer characteristics can be seen graphically by use of data from selected representative studies. Water samples collected in September and November 1996, from 46 springs throughout the watershed were analyzed for chlorofluorocarbons (CFC?s) to estimate the apparent age of ground water. For comparison purposes, apparent ages of water from springs were calculated assuming piston flow. Additi-onal data are given to estimate apparent ages assuming an exponential distribution of ages in spring discharge. Additionally, results from previous studies of CFC-dating of ground water from other springs and wells in the watershed were compiled. The CFC data, and the data on major ions, nutrients, and nitrogen isotopes in the water collected from the 46 springs are included in this report. The apparent ages of water

  14. Hydrologic and Climatic Variability in and Modeling of Streamwater Sulfate Concentrations at Panola Mountain Research Watershed, Georgia, U.S.A.

    NASA Astrophysics Data System (ADS)

    Aulenbach, B. T.; Huntington, T. G.

    2015-12-01

    Variability in streamwater sulfate concentrations at Panola Mountain Research Watershed (PMRW), a small 41-hectare forested watershed near Atlanta, Georgia, U.S.A., was assessed for the period 1996-2012. The source of sulfate at PMRW is predominantly atmospheric deposition of which about 85% is retained within the watershed. Sulfate concentrations increase with increasing streamflow due to an increasing contribution of soil water, which has higher concentrations than that of groundwater. Sulfate concentrations also increased when an intermittent stream in the upper part of the watershed with higher sulfate concentrations contributed larger portions to total streamflow. The highest streamwater sulfate concentrations were observed in hydrologic events that occurred during periods of wetting up after long periods of drought, which were most evident during July through December. These high sulfate concentrations presumably are the result of desorption of sulfate from the shallow soils that accumulated during droughts. Simple concentration-discharge models were fairly weak, with a model R2 of about 0.35, but improved to an R2 of about 0.4 when adding the ratio of streamflow between the upper part of the watershed and the outlet as an independent variable. Additional model improvements were attempted by separating the samples into various groups based on: (1) time of year that high sulfate values were observed; (2) current drought conditions, and; (3) drought conditions during the previous growing season. The largest improvements occurred when separate models were made based on the drought conditions during the previous growing season with model R2s ranging from 0.43 to 0.67 and improvement was observed across all prior drought conditions. The use of hydrologic and climatic variables and categorization led to an enhanced understanding of the factors that affect water-quality variability, and can strengthen predictions of concentrations and estimates of loads.

  15. Characterizing Storm Event Dynamics of a Forested Watershed in the Lower Atlantic Coastal Plain, South Carolina USA

    NASA Astrophysics Data System (ADS)

    Latorre Torres, I. B.; Amatya, D. M.; Callahan, T. J.; Levine, N. S.

    2007-12-01

    Hydrology research in the Southeast U.S. has primarily focused on upland mountainous areas; however, much less is known about hydrological processes in Lower Coastal Plain (LCP) watersheds. Such watersheds are difficult to characterize due to shallow water table conditions, low topographic gradient, complex surface- subsurface water interaction, and lack of detailed soil information. Although opportunities to conduct long term monitoring in relatively undeveloped watersheds are often limited, stream flow and rainfall in the Turkey Creek watershed (third-order watershed, about 7200 ha in the Francis Marion National Forest near Charleston, SC) have been monitored since 1964. In this study, event runoff-rainfall ratios have been determined for 51 storm events using historical data from 1964-1973. One of our objectives was to characterize relationships between seasonal event rainfall and storm outflow in this watershed. To this end, observed storm event data were compared with values predicted by established hydrological methods such as the Soil Conservation Service runoff curve number (SCS-CN) and the rational method integrated within a Geographical Information System (GIS), to estimate total event runoff and peak discharge, respectively. Available 1:15000 scale aerial images were digitized to obtain land uses, which were used with the SCS soil hydrologic groups to obtain the runoff coefficients (C) for the rational method and the CN values for the SCS-CN method. These methods are being tested with historical storm event responses in the Turkey Creek watershed scale, and then will be used to predict event runoff in Quinby Creek, an ungauged third-order watershed (8700 ha) adjacent to Turkey Creek. Successful testing with refinement of parameters in the rational method and SCS-CN method, both designed for small urban and agricultural dominated watersheds, may allow widespread application of these methods for studying the event rainfall-runoff dynamics for similar

  16. Distribution of heavy metals and foraminiferal assemblages in sediments of Biscayne Bay, Florida, USA

    USGS Publications Warehouse

    Carnahan, E.A.; Hoare, A.M.; Hallock, P.; Lidz, B.H.; Reich, C.D.

    2008-01-01

    Heavy-metal pollution is an issue of concern in estuaries influenced by agriculture, urban, and harbor activities. Foraminiferal assemblages have been shown to be effective indicators of pollution. Sediment samples (n = 110) from Biscayne Bay were analyzed for heavy metals, foraminiferal assemblages, and grain-size distribution. Highest Cu, Zn, Cr, Hg, Pb, and Ni concentrations were found closest to Miami and near the mouths of several canals along the western margin of the bay. Few samples exceeded limits of possible biological effects as defined by previous studies. Ammonia and Cribroelphidium, two known stress-tolerant genera, correlated positively with Cu, Zn, Hg, and Ni (r ??? 0.43). Symbiont-bearing foraminifers, Archaias, Laevipeneroplis, and Androsina, correlated negatively with Cu, Zn, Hg, and Ni (r ??? -0.26).

  17. A seasonal comparison of surface sediment characteristics in Chincoteague Bay, Maryland and Virginia, USA

    USGS Publications Warehouse

    Ellis, Alisha M.; Marot, Marci E.; Wheaton, Cathryn J.; Bernier, Julie C.; Smith, Christopher G.

    2016-02-03

    This report is an archive for sedimentological data derived from the surface sediment of Chincoteague Bay. Data are available for the spring (March/April 2014) and fall (October 2014) samples collected. Downloadable data are provided as Excel spreadsheets and as JPEG files. Additional files include ArcGIS shapefiles of the sampling sites, detailed results of sediment grain-size analyses, and formal Federal Geographic Data Committee metadata (data downloads).

  18. Modeling the Effect of Hypoxia on Macrobenthos Production in the Lower Rappahannock River, Chesapeake Bay, USA

    PubMed Central

    Sturdivant, Samuel Kersey; Brush, Mark J.; Diaz, Robert J.

    2013-01-01

    Hypoxia in Chesapeake Bay has substantially increased in recent decades, with detrimental effects on macrobenthic production; the production of these fauna link energy transfer from primary consumers to epibenthic and demersal predators. As such, the development of accurate predictive models that determine the impact of hypoxia on macrobenthic production is important. A continuous-time, biomass-based model was developed for the lower Rappahannock River, a Bay tributary prone to seasonal hypoxia. Phytoplankton, zooplankton, and macrobenthic state variables were modeled, with a focus on quantitatively constraining the effect of hypoxia on macrobenthic biomass. This was accomplished through regression with Z': a sigmoidal function between macrobenthic biomass and dissolved oxygen concentration, derived using macrobenthic data collected from the Rappahannock River during the summers of 2007 and 2008, and applied to compute hypoxia-induced mortality as a rate process. The model was verified using independent monitoring data collected by the Chesapeake Bay Program. Simulations showed that macrobenthic biomass was strongly linked to dissolved oxygen concentrations, with fluctuations in biomass related to the duration and severity of hypoxia. Our model demonstrated that hypoxia negatively affected macrobenthic biomass, as longer durations of hypoxia and greater hypoxic severity resulted in an increasing loss in biomass. This exercise represents an important contribution to modeling anthropogenically impacted coastal ecosystems, by providing an empirically constrained relationship between hypoxia and macrobenthic biomass, and applying that empirical relationship in a mechanistic model to quantify the effect of the severity, duration, and frequency of hypoxia on benthic biomass dynamics. PMID:24391904

  19. Paleoenvironmental assessment of recent environmental changes in Florida Bay, USA: a biomarker based study

    USGS Publications Warehouse

    Xu, Y.; Holmes, C.W.; Jaffe, R.

    2007-01-01

    The extractable lipid compositions in four Florida Bay cores were determined in order to understand environmental changes over the last 160 years. The most significant environmental change was recorded by oscillations in the amplitude and frequency of biomarkers during the 20th century. Two seagrass molecular proxies (Paq and the C25/C27n-alkan-2-one ratio) reached a maximum post 1900, suggesting that abundant seagrass communities existed during the 20th century. A sharp drop in the Paq value from 0.65 to 0.48 in the central Bay at about 1987 seems to reflect seagrass die-off. The concentrations of microbial biomarkers (C20 HBIs, C25 HBIs and dinosterol) substantially increased after 1950 in the TC, BA and NB cores, reflecting an increase in algal (planktonic organism) primary productivity. However, the RB core presented the highest abundance of C25 HBIs and dinosterol during the period of 1880–1940, suggesting historically large inputs from diatoms and dinoflagellates. A substantial rise in abundance of taraxerol (a specific biomarker of mangroves) from 20 μg/g TOC in the 1830s to 279 μg/g TOC in the l980s is likely a result of increased mangrove primary productivity along the shore of the NE Bay. These changes are most likely the result of hydrological alterations in South Florida.

  20. Long time-series of turbid coastal water using AVHRR: An example from Florida Bay, USA

    USGS Publications Warehouse

    Stumpf, R.P.; Frayer, M.L.

    1997-01-01

    The AVHRR can provide information on the reflectance of turbid case II water, permitting examination of large estuaries and plumes from major rivers. The AVHRR has been onboard several NOAA satellites, with afternoon overpasses since 1981, offering a long time-series to examine changes in coastal water. We are using AVHRR data starting in December 1989, to examine water clarity in Florida Bay, which has undergone a decline since the late 1980's. The processing involves obtaining a nominal reflectance for red light with standard corrections including those for Rayleigh and aerosol path radiances. Established relationships between reflectance and the water properties being measured in the Bay provide estimates of diffuse attenuation and light limitation for phytoplankton and seagrass productivity studies. Processing also includes monthly averages of reflectance and attenuation. The AVHRR data set describes spatial and temporal patterns, including resuspension of bottom sediments in the winter, and changes in water clarity. The AVHRR also indicates that Florida Bay has much higher reflectivity relative to attenuation than other southeastern US estuaries. ??2005 Copyright SPIE - The International Society for Optical Engineering.

  1. Biogeochemical and Hydrological Controls on Mercury and Methylmercury in First Order Coastal Plain Watersheds of the Chesapeake Bay

    NASA Astrophysics Data System (ADS)

    Heyes, A.; Gilmour, C. C.; Bell, J. T.; Butera, D.; McBurney, A. W.

    2015-12-01

    Over the past 7 years we made use of the long-term research site at the Smithsonian Environmental Research Center (SERC) in central Maryland to study the fluxes of mercury (Hg) and methylmercury (MeHg) in three small first-order mid-Atlantic coastal plain watersheds. One watershed is entirely forested, one watershed is primarily agriculture with a forested stream buffer, and one watershed is mixed land use but contains a beaver produced wetland pond. Our initial goals were to assess watershed Hg yields in the mid-Atlantic and to establish a baseline prior to implementation of Hg emissions controls. All three studied watersheds produced relatively high yields of Hg, with the greatest yield coming from the forested watershed. Our initial evaluation of three watersheds showed that MeHg production and flux could also be high, but varied dramatically among watersheds and across years and seasons. During each year we observed episodic MeHg production in the spring and sometimes during prolonged high-flow storm events in the fall. The observed spring maxima of MeHg release coincided with development of anoxia in riparian groundwater. MeHg accumulation in riparian groundwater began once nitrate was depleted and either iron accumulation or sulfate depletion of groundwater began. We propose the presence of nitrate was modulating MeHg production through the suppression of sulfate and iron reducers and perhaps methanogens. As sulfate is not limiting in any of the watersheds owing to the sediments marine origin, we hypothesize the depletion of nitrate allows sulfate reducing bacteria to now utilize available carbon. Although wetlands are generally thought of as the primary zones of MeHg production in watersheds, shallow riparian groundwaters very close to the stream appear to play that role in SERC Coastal Plain watersheds. We hypothesize that the balance between nitrate, sulfate and other microbial electron acceptors in watersheds is a major control on MeHg production. Land

  2. Comparison of two regression-based approaches for determining nutrient and sediment fluxes and trends in the Chesapeake Bay watershed

    USGS Publications Warehouse

    Moyer, Douglas; Hirsch, Robert M.; Hyer, Kenneth

    2012-01-01

    Nutrient and sediment fluxes and changes in fluxes over time are key indicators that water resource managers can use to assess the progress being made in improving the structure and function of the Chesapeake Bay ecosystem. The U.S. Geological Survey collects annual nutrient (nitrogen and phosphorus) and sediment flux data and computes trends that describe the extent to which water-quality conditions are changing within the major Chesapeake Bay tributaries. Two regression-based approaches were compared for estimating annual nutrient and sediment fluxes and for characterizing how these annual fluxes are changing over time. The two regression models compared are the traditionally used ESTIMATOR and the newly developed Weighted Regression on Time, Discharge, and Season (WRTDS). The model comparison focused on answering three questions: (1) What are the differences between the functional form and construction of each model? (2) Which model produces estimates of flux with the greatest accuracy and least amount of bias? (3) How different would the historical estimates of annual flux be if WRTDS had been used instead of ESTIMATOR? One additional point of comparison between the two models is how each model determines trends in annual flux once the year-to-year variations in discharge have been determined. All comparisons were made using total nitrogen, nitrate, total phosphorus, orthophosphorus, and suspended-sediment concentration data collected at the nine U.S. Geological Survey River Input Monitoring stations located on the Susquehanna, Potomac, James, Rappahannock, Appomattox, Pamunkey, Mattaponi, Patuxent, and Choptank Rivers in the Chesapeake Bay watershed. Two model characteristics that uniquely distinguish ESTIMATOR and WRTDS are the fundamental model form and the determination of model coefficients. ESTIMATOR and WRTDS both predict water-quality constituent concentration by developing a linear relation between the natural logarithm of observed constituent

  3. Organic carbon and fine sediment production potential from decaying permafrost in a small watershed, Sheldrake River, Eastern coastal region of Hudson Bay

    NASA Astrophysics Data System (ADS)

    Jolivel, M.; Allard, M.

    2010-12-01

    Recent evaluations indicate that large amounts of organic carbon and fine sediment can be released in fluvial and coastal systems because of permafrost degradation, with impacts on ecosystems. In order to estimate the organic carbon and fine sediment potential production from a river basin, we have made a spatiotemporal comparison between 1957 aerial photographs and a 2009 GeoEye satellite image. A gauging station was installed near the river mouth and measurements of the extent and volume of permafrost degradation were made in the watershed where permafrost degradation is very active. The Sheldrake river watershed is located on the eastern coast of Hudson Bay near the Inuit community of Umiujaq, in the discontinuous permafrost zone. The tree line passes across the watershed. Permafrost mounds (palsas, lithalsas) and plateaus are the most abundant permafrost landforms in this area. They developed principally in east-west oriented valleys, in postglacial marine silts of the Tyrrell Sea. Signs of degradation are numerous. Lithalsas and palsas (with peat cover) weather out and collapse. Thermokarst ponds are replacing permafrost mounds and sometimes, eroded clay and peat are remobilized in the drainage network. Moreover, several retrogressive landslides, mudflows and gully erosion are active along the Sheldrake river banks. The first step consisted in mapping the 80 km2 watershed area and representing surface deposits, drainage network and permafrost distribution (1957 and 2009). First results show that 40 to 70% of the 1957 permafrost has disappeared in 2009 in various sector of the watershed. The percentage of permafrost degradation is positively correlated with distance from the sea and the presence of a well-developed drainage network. The second step is to calculate an equation which will allow changing the missing permafrost surface between 1957 and 2009 into a volume. The equation will take into account the average depth of permafrost and active layer, the mean

  4. Evaluating the source of streamwater nitrate using δ15N and δ18O in nitrate in two watersheds in New Hampshire, USA

    USGS Publications Warehouse

    Pardo, Linda H.; Kendall, Carol; Pett-Ridge, Jennifer; Chang, Cecily C.Y.

    2004-01-01

    The natural abundance of nitrogen and oxygen isotopes in nitrate can be a powerful tool for identifying the source of nitrate in streamwater in forested watersheds, because the two main sources of nitrate, atmospheric deposition and microbial nitrification, have distinct δ18O values. Using a simple mixing model, we estimated the relative fractions in streamwater derived from these sources for two forested watersheds with markedly different streamwater nitrate outputs. In this study, we monitored δ15N and δ18O of nitrate biweekly in atmospheric deposition and in streamwater for 20 months at the Hubbard Brook Experimental Forest, New Hampshire, USA (moderate nitrogen export), and monthly in streamwater at the Bowl Research Natural Area, New Hampshire, USA (high nitrogen export). For rain, δ18O values ranged from +47 to +77‰ (mean: +58‰) and δ15N from −5 to +1‰ (mean: −3‰); for snow, δ18O values ranged from +52 to +75‰ (mean: +67‰) and δ15N from −3 to +2‰ (mean: −1‰). Streamwater nitrate, in contrast to deposition, had δ18O values between +12 and +33‰ (mean: +18‰) and δ15N between −3 and +6‰ (mean: 0‰). Since nitrate produced by nitrification typically has δ18O values ranging from −5 to +15‰, our field data suggest that most of the nitrate lost from the watersheds in streamflow was nitrified within the catchment. Our results confirm the importance of microbial nitrogen transformations in regulating nitrogen losses from forested ecosystems and suggest that hydrologic storage may be a factor in controlling catchment nitrate losses.

  5. Mass balances of mercury and nitrogen in burned and unburned forested watersheds at Acadia National Park, Maine, USA.

    PubMed

    Nelson, S J; Johnson, K B; Kahl, J S; Haines, T A; Fernandez, I J

    2007-03-01

    Precipitation and streamwater samples were collected from 16 November 1999 to 17 November 2000 in two watersheds at Acadia National Park, Maine, and analyzed for mercury (Hg) and dissolved inorganic nitrogen (DIN, nitrate plus ammonium). Cadillac Brook watershed burned in a 1947 fire that destroyed vegetation and soil organic matter. We hypothesized that Hg deposition would be higher at Hadlock Brook (the reference watershed, 10.2 microg/m(2)/year) than Cadillac (9.4 microg/m(2)/year) because of the greater scavenging efficiency of the softwood vegetation in Hadlock. We also hypothesized the Hg and DIN export from Cadillac Brook would be lower than Hadlock Brook because of elemental volatilization during the fire, along with subsequently lower rates of atmospheric deposition in a watershed with abundant bare soil and bedrock, and regenerating vegetation. Consistent with these hypotheses, Hg export was lower from Cadillac Brook watershed (0.4 microg/m(2)/year) than from Hadlock Brook watershed (1.3 microg/m(2)/year). DIN export from Cadillac Brook (11.5 eq/ha/year) was lower than Hadlock Brook (92.5 eq/ha/year). These data show that approximately 50 years following a wildfire there was lower atmospheric deposition due to changes in forest species composition, lower soil pools, and greater ecosystem retention for both Hg and DIN.

  6. Ground water flow analysis of a mid-Atlantic outer coastal plain watershed, Virginia, U.S.A.

    PubMed

    Robinson, Michael A; Reay, William G

    2002-01-01

    Models for ground water flow (MODFLOW) and particle tracking (MODPATH) were used to determine ground water flow patterns, principal ground water discharge and recharge zones, and estimates of ground water travel times in an unconfined ground water system of an outer coastal plain watershed on the Delmarva Peninsula, Virginia. By coupling recharge and discharge zones within the watershed, flowpath analysis can provide a method to locate and implement specific management strategies within a watershed to reduce ground water nitrogen loading to surface water. A monitoring well network was installed in Eyreville Creek watershed, a first-order creek, to determine hydraulic conductivities and spatial and temporal variations in hydraulic heads for use in model calibration. Ground water flow patterns indicated the convergence of flow along the four surface water features of the watershed; primary discharge areas were in the nontidal portions of the watershed. Ground water recharge zones corresponded to the surface water features with minimal development of a regional ground water system. Predicted ground water velocities varied between < 0.01 to 0.24 m/day, with elevated values associated with discharge areas and areas of convergence along surface water features. Some ground water residence times exceeded 100 years, although average residence times ranged between 16 and 21 years; approximately 95% of the ground water resource would reflect land use activities within the last 50 years.

  7. Mass balances of mercury and nitrogen in burned and unburned forested watersheds at Acadia National Park, Maine, USA

    USGS Publications Warehouse

    Nelson, S.J.; Johnson, K.B.; Kahl, J.S.; Haines, T.A.; Fernandez, I.J.

    2007-01-01

    Precipitation and streamwater samples were collected from 16 November 1999 to 17 November 2000 in two watersheds at Acadia National Park, Maine, and analyzed for mercury (Hg) and dissolved inorganic nitrogen (DIN, nitrate plus ammonium). Cadillac Brook watershed burned in a 1947 fire that destroyed vegetation and soil organic matter. We hypothesized that Hg deposition would be higher at Hadlock Brook (the reference watershed, 10.2 ??g/m2/year) than Cadillac (9.4 ??g/m2/year) because of the greater scavenging efficiency of the softwood vegetation in Hadlock. We also hypothesized the Hg and DIN export from Cadillac Brook would be lower than Hadlock Brook because of elemental volatilization during the fire, along with subsequently lower rates of atmospheric deposition in a watershed with abundant bare soil and bedrock, and regenerating vegetation. Consistent with these hypotheses, Hg export was lower from Cadillac Brook watershed (0.4 ??g/m2/year) than from Hadlock Brook watershed (1.3 ??g/m2/year). DIN export from Cadillac Brook (11.5 eq/ ha/year) was lower than Hadlock Brook (92.5 eq/ha/year). These data show that ??50 years following a wildfire there was lower atmospheric deposition due to changes in forest species composition, lower soil pools, and greater ecosystem retention for both Hg and DIN. ?? Springer Science + Business Media B.V. 2006.

  8. Organochlorine contaminants and Tree Swallows along the Fox River and Green Bay, Wisconsin, USA

    USGS Publications Warehouse

    Custer, Christine M.; Custer, T.W.; Allen, P.D.; Stromborg, K.L.; Melancon, M.J.; Adams, N.J.; Slotow, R.H.

    1999-01-01

    Green Bay, Wisconsin is contaminated with polychlorinated biphenyls (PCBs) however, whether these contaminants affect reproduction in insectivorous birds is unknown. Tree Swallows, Tachycineta bicolor, are secondary cavity nesters that will nest in boxes and tolerate handling. Because Tree Swallows are aquatic insectivores, residues in their tissues are primarily indicative of contaminants in sediments. We studied swallows at two contaminated and two reference colonies in 1993, 1994, and 1995 in the Green Bay area. Swallows at the two contaminated sites had significantly higher PCB levels in eggs when compared to two reference sites. Eggs from clutches that contained dead embryos had higher PCB concentrations than eggs from clutches where all eggs hatched; there were no contaminant effects overall on reproduction, however. Twelve-day-old nestlings at the two contaminated sites accumulated significantly more PCBs than did nestlings at the reference sites demonstrating that PCB contamination came from the local area. The PCB congener profile in 12-day-old nestlings mirrored the congener profile in their food.

  9. Organochlorine contaminants and Tree Swallows along the Fox River and Green Bay, Wisconsin, USA

    USGS Publications Warehouse

    Custer, Christine M.; Custer, T.W.; Allen, P.D.; Stromborg, K.L.; Melancon, M.J.; Adams, N.J.; Slotow, R.H.

    1998-01-01

    Green Bay, Wisconsin is contaminated with polychlorinated biphenyls (PCBs) however, whether these contaminants affect reproduction in insectivorous birds is unknown. Tree Swallows, Tachycineta bicolor, are secondary cavity nesters that will nest in boxes and tolerate handling. Because Tree Swallows are aquatic insectivores, residues in their tissues are primarily indicative of contaminants in sediments. We studied swallows at two contaminated and two reference colonies in 1993, 1994, and 1995 in the Green Bay area. Swallows at the two contaminated sites had significantly higher PCB levels in eggs when compared to two reference sites. Eggs from clutches that contained dead embryos had higher PCB concentrations than eggs from clutches where all eggs hatched; there were no contaminant effects overall on reproduction, however. Twelve-day-old nestlings at the two contaminated sites accumulated significantly more PCBs than did nestlings at the reference sites demonstrating that PCB contamination came from the local area. The PCB congener profile in 12-day-old nestlings mirrored the congener profile in their food.

  10. Dispersal and recruitment of blue crab larvae in Delaware Bay, U.S.A.

    NASA Astrophysics Data System (ADS)

    Epifanio, C. E.; Valenti, C. C.; Pembroke, A. E.

    1984-01-01

    Results of a three-year survey of the occurrence of Callinectes sapidus larvae in the mouth of Delaware Bay indicated that stage I zoea larvae were most abundant insurface water as compared to mid-depths and near bottom. The major peak in abundance of stage I zoea larvae occurred in early August with a secondary peak in early September. Peaks in abundance of megalopae occurred five weeks after the respective peaks in zoeal abundance. Zoea stages II-VIII were not collected in the bay mouth. Results of sampling every 3 h over consecutive tidal cycles showed that stage I zoea larvae were most common in the water column on ebbing tidal currents. Megalopae were most common in the water column on flooding tidal currents, suggesting a tidally related, vertical migration. It was concluded that stage I zoea larvae are flushed from the estuary and undergo development on the continental shelf. Megalopae are then transported back to inshore waters by a combination of winds and currents and invade the estuary by means of migration into the water column on flooding tidal currents and migration to the bottom on ebbing tidal currents.

  11. Neogene folding and faulting in southern Monterey Bay, Central California, USA

    USGS Publications Warehouse

    Gardner-Taggart, J. M.; Greene, H. Gary; Ledbetter, M.T.

    1993-01-01

    The goal of this study was to determine the Neogene structural history of southern Monterey Bay by mapping and correlating the shallow tectonic structures with previously identified deeper occurring structures. Side scan sonographs and Uniboom seismic reflection profiles collected in the region suggest that deformation associated with both compressional and transcurrent movement is occurring. Strike-slip movement between the North American and Pacific plates started as subduction ceased 21 Ma, creating the San Andreas fault system. Clockwise rotation of the Pacific plate occurred between 3.4 and 3.9 Ma causing orthogonal convergence between the two plates. This plate rotation is responsible for compressional Neogene structures along the central California coast. Structures exhibit transpressional tectonic characteristics such as thrust faulting, reverse faulting and asymmetrical folding. Folding and faulting are confined to middle Miocene and younger strata. Shallow Mesozoic granitic basement rocks either crop out or lie near the surface in most of the region and form a possible de??collement along which the Miocene Monterey Formation has decoupled and been folded. Over 50% of the shallow faults strike normal (NE-SW) to the previously identified faults. Wrench fault tectonics complicated by compression, gradual uplift of the basement rocks, and a change in plate convergence direction are responsible for the observed structures in southern Monterey Bay. ?? 1993.

  12. Integrated ecosystem services assessment: Valuation of changes due to sea level rise in Galveston Bay, Texas, USA.

    PubMed

    Yoskowitz, David; Carollo, Cristina; Pollack, Jennifer Beseres; Santos, Carlota; Welder, Kathleen

    2017-03-01

    The goal of the present study was to identify the potential changes in ecosystem service values provided by wetlands in Galveston Bay, Texas, USA, under the Intergovernmental Panel on Climate Change (IPCC) A1B max (0.69 m) sea level rise scenario. Built exclusively upon the output produced during the Sea Level Affecting Marshes Model 6 (SLAMM 6) exercise for the Galveston Bay region, this study showed that fresh marsh and salt marsh present a steady decline from 2009 (initial condition) to 2100. Fresh marsh was projected to undergo the biggest changes, with the loss of approximately 21% of its extent between 2009 and 2100 under the A1B max scenario. The percentages of change for salt marsh were less prominent at approximately 12%. This trend was also shown in the values of selected ecosystem services (disturbance regulation, waste regulation, recreation, and aesthetics) provided by these habitats. An ordinary least squares regression was used to calculate the monetary value of the selected ecosystem services provided by salt marsh and fresh marsh in 2009, and in 2050 and 2100 under the A1B max scenario. The value of the selected services showed potential monetary losses in excess of US$40 million annually in 2100, compared to 2009 for fresh marsh and more than $11 million for salt marsh. The estimates provided here are only small portions of what can be lost due to the decrease in habitat extent, and they highlight the need for protecting not only built infrastructure but also natural resources from sea level rise. Integr Environ Assess Manag 2017;13:431-443. © 2016 SETAC.

  13. Mass-balance modeling of mineral weathering rates and CO2 consumption in the forested, metabasaltic Hauver Branch watershed, Catoctin Mountain, Maryland, USA

    USGS Publications Warehouse

    Rice, Karen; Price, Jason R.; Szymanski, David W.

    2013-01-01

    Mineral weathering rates and a forest macronutrient uptake stoichiometry were determined for the forested, metabasaltic Hauver Branch watershed in north-central Maryland, USA. Previous studies of Hauver Branch have had an insufficient number of analytes to permit determination of rates of all the minerals involved in chemical weathering, including biomass. More equations in the mass-balance matrix were added using existing mineralogic information. The stoichiometry of a deciduous biomass term was determined using multi-year weekly to biweekly stream-water chemistry for a nearby watershed, which drains relatively unreactive quartzite bedrock.At Hauver Branch, calcite hosts ~38 mol% of the calcium ion (Ca2+) contained in weathering minerals, but its weathering provides ~90% of the stream water Ca2+. This occurs in a landscape with a regolith residence time of more than several Ka (kiloannum). Previous studies indicate that such old regolith does not typically contain dissolving calcite that affects stream Ca2+/Na+ ratios. The relatively high calcite dissolution rate likely reflects dissolution of calcite in fractures of the deep critical zone.Of the carbon dioxide (CO2) consumed by mineral weathering, calcite is responsible for approximately 27%, with the silicate weathering consumption rate far exceeding that of the global average. The chemical weathering of mafic terrains in decaying orogens thus may be capable of influencing global geochemical cycles, and therefore, climate, on geological timescales. Based on carbon-balance calculations, atmospheric-derived sulfuric acid is responsible for approximately 22% of the mineral weathering occurring in the watershed. Our results suggest that rising air temperatures, driven by global warming and resulting in higher precipitation, will cause the rate of chemical weathering in the Hauver Branch watershed to increase until a threshold temperature is reached. Beyond the threshold temperature, increased recharge would

  14. Identifying fecal pollution sources using 3M(™) Petrifilm (™) count plates and antibiotic resistance analysis in the Horse Creek Watershed in Aiken County, SC (USA).

    PubMed

    Harmon, S Michele; West, Ryan T; Yates, James R

    2014-12-01

    Sources of fecal coliform pollution in a small South Carolina (USA) watershed were identified using inexpensive methods and commonly available equipment. Samples from the upper reaches of the watershed were analyzed with 3M(™) Petrifilm(™) count plates. We were able to narrow down the study's focus to one particular tributary, Sand River, that was the major contributor of the coliform pollution (both fecal and total) to a downstream reservoir that is heavily used for recreation purposes. Concentrations of total coliforms ranged from 2,400 to 120,333 cfu/100 mL, with sharp increases in coliform counts observed in samples taken after rain events. Positive correlations between turbidity and fecal coliform counts suggested a relationship between fecal pollution and stormwater runoff. Antibiotic resistance analysis (ARA) compared antibiotic resistance profiles of fecal coliform isolates from the stream to those of a watershed-specific fecal source library (equine, waterfowl, canines, and untreated sewage). Known fecal source isolates and unknown isolates from the stream were exposed to six antibiotics at three concentrations each. Discriminant analysis grouped known isolates with an overall average rate of correct classification (ARCC) of 84.3 %. A total of 401 isolates from the first stream location were classified as equine (45.9 %), sewage (39.4 %), waterfowl (6.2 %), and feline (8.5 %). A similar pattern was observed at the second sampling location, with 42.6 % equine, 45.2 % sewage, 2.8 % waterfowl, 0.6 % canine, and 8.8 % feline. While there were slight weather-dependent differences, the vast majority of the coliform pollution in this stream appeared to be from two sources, equine and sewage. This information will contribute to better land use decisions and further justify implementation of low-impact development practices within this urban watershed.

  15. The effects of a whole-watershed calcium addition on the chemistry of stream storm events at the Hubbard Brook Experimental Forest in NH, USA.

    PubMed

    Cho, Youngil; Driscoll, Charles T; Blum, Joel D

    2009-10-01

    Patterns of storm runoff chemistry from a wollastonite (calcium-silicate mineral, CaSiO(3)) treated watershed (W1) were compared with a reference watershed (W6) at the Hubbard Brook Experimental Forest (HBEF) in New Hampshire (NH), USA to investigate the role of Ca(2+) supply in the acid-base status of stream chemistry. In the summer of 2003, six storm events were studied in W1 and W6 to evaluate the effects of the wollastonite treatment on the episodic acidification of stream waters. Although mean values of Ca(2+) concentrations decreased slightly from 33.8 to 31.7 mumol/L with increasing stream discharge in W1 during the events, the mean value of acid neutralizing capacity (ANC) was positive (1.2 mueq/L) during storm events, compared to negative values (-0.2 mueq/L) in W6. This pattern is presumably due to enhanced Ca(2+) supply in W1 (20.7 to 29.0% of dissolved Ca(2+) derived from the added wollastonite) to stream water as a result of interflow along shallow flowpaths. In addition, the application of wollastonite increased pH and dissolved silica (H(4)SiO(4)) concentrations, and decreased the concentration of inorganic monomeric Al (Al(i)) in W1 in comparison with W6 during storm events. Despite an increase in SO(4)(2-) concentration, likely due to desorption of sulfate from soil after the treatment, the watershed showed an increase in ANC compared to the reference watershed, serving to mitigate episodic acidification.

  16. Evaluation of Soil Moisture, Storm Characteristics, and Their Influence on Storm Runoff and Water Yield at the Panola Mountain Research Watershed, Georgia, U.S.A.

    NASA Astrophysics Data System (ADS)

    Riley, J. W.; Aulenbach, B. T.

    2015-12-01

    Understanding the factors that control runoff processes is important for many aspects of water supply and ecosystem protection, especially during climatic extremes that result in flooding or droughts; potentially impacting human safety. Furthermore, having knowledge of the conditions during which runoff occurs contributes to the conceptual understanding of the hydrologic cycle and may improve parameterization of hydrologic models. We evaluated soil moisture, storm characteristics, and the subsequent runoff and water yield for 297 storms over an eight-year period at Panola Mountain Research Watershed to better understand runoff generation processes. Panola Mountain Research Watershed is a small (41-hectare), relatively undisturbed forested watershed near Atlanta, GA, U.S.A. Strong relations were observed between total precipitation for a given storm, deep (70 cm below surface) antecedent soil moisture content and the volume of runoff. However, the strength of the relations varied based on occurrence during the growing (April - September; 172 storms) or dormant (October - March; 125 storms) period. In general, soil moisture responded at a minimum of 15 cm depth for all but 18 events. In addition, we found storms that initiated a response of deep soil moisture (70 cm below surface) to be an important factor relating to storm runoff and water yield. Seventy percent of the dormant period storms generated a response at 70 cm depth compared to 58% of growing period storms. A stronger relation between soil moisture and water yield was noted during the dormant period and indicated that all storms that produced a water yield >12% occurred when deep pre-event soil moisture was >20%. Similar patterns were also present during the growing season with occasional intense thunderstorms also generating higher water yields even in the absence of high soil moisture. The importance of deep soil moisture likely reflects the overall status of watershed storage conditions.

  17. From provocative narrative scenarios to quantitative biophysical model results: Simulating plausible futures to 2070 in an urbanizing agricultural watershed in Wisconsin, USA

    NASA Astrophysics Data System (ADS)

    Booth, E.; Chen, X.; Motew, M.; Qiu, J.; Zipper, S. C.; Carpenter, S. R.; Kucharik, C. J.; Steven, L. I.

    2015-12-01

    Scenario analysis is a powerful tool for envisioning future social-ecological change and its consequences on human well-being. Scenarios that integrate qualitative storylines and quantitative biophysical models can create a vivid picture of these potential futures but the integration process is not straightforward. We present - using the Yahara Watershed in southern Wisconsin (USA) as a case study - a method for developing quantitative inputs (climate, land use/cover, and land management) to drive a biophysical modeling suite based on four provocative and contrasting narrative scenarios that describe plausible futures of the watershed to 2070. The modeling suite consists of an agroecosystem model (AgroIBIS-VSF), hydrologic routing model (THMB), and empirical lake water quality model and estimates several biophysical indicators to evaluate the watershed system under each scenario. These indicators include water supply, lake flooding, agricultural production, and lake water quality. Climate (daily precipitation and air temperature) for each scenario was determined using statistics from 210 different downscaled future climate projections for two 20-year time periods (2046-2065 and 2081-2100) and modified using a stochastic weather generator to allow flexibility for matching specific climate events within the scenario narratives. Land use/cover for each scenario was determined first by quantifying changes in areal extent every decade for 15 categories at the watershed scale to be consistent with the storyline events and theme. Next, these changes were spatially distributed using a rule-based framework based on land suitability metrics that determine transition probabilities. Finally, agricultural inputs including manure and fertilizer application rates were determined for each scenario based on the prevalence of livestock, water quality regulations, and technological innovations. Each scenario is compared using model inputs (maps and time-series of land use/cover and

  18. Chloride cycling in two forested lake watersheds in the west-central Adirondack Mountains, New York, U.S.A.

    USGS Publications Warehouse

    Peters, N.E.

    1991-01-01

    The chemistry of precipitation, throughfall, soil water, ground water, and surface water was evaluated in two forested lake-watersheds over a 4-yr period to assess factors controlling C1- cycling. Results indicate that C1- cycling in these watersheds is more complex than the generally held view of the rapid transport of atmospherically derived C1- through the ecosystem. The annual throughfall Cl- flux for individual species in the northern hardwood forest was 2 to 5 times that of precipitation (56 eq ha-1), whereas the Na+ throughfall flux, in general, was similar to the precipitation flux. Concentrations of soil-water Cl- sampled from ceramic tension lysimeters at 20 cm below land surface generally exceeded the Na+ concentrations and averaged 31 ??eq L-1, the highest of any waters sampled in the watersheds, except throughfall under red spruce which averaged 34 ??eq L-1. Chloride was concentrated prior to storms and mobilized rapidly during storms as suggested by increases in streamwater Cl- concentrations with increasing flow. Major sources of Cl- in both watersheds are the forest floor and hornblende weathering in the soils and till. In the Panther Lake watershed, which contains mainly thick deposits of till( > 3 m), hornblende weathering results in a net Cl- flux 3 times greater than that in the Woods Lake watershed, which contains mainly thin deposits of till. The estimated accumulation rate of Cl- in the biomass of the two watersheds was comparable to the precipitation Cl- flux.The chemistry of precipitation, throughfall, soil water, ground water, and surface water was evaluated in two forested lake-watersheds over a 4-yr period to assess factors controlling Cl- cycling. Results indicate that Cl- cycling in these watersheds is more complex than the generally held view of the rapid transport of atmospherically derived Cl- through the excosystem. The annual throughfall Cl- flux for individual species in the northern hardwood forest was 2 to 5 times that of

  19. Evaluating the potential role of denitrifying bioreactors in reducing watershed-scale nitrate loads: A case study comparing three Midwestern (USA) watersheds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The transport of nitrate (NO3-N) from agricultural lands to surface waters is a complex and recalcitrant problem. Subsurface drainage systems that are especially prevalent in the corn-growing regions of the Midwestern USA facilitate NO3-N transport. Several conservation practices, including fertiliz...

  20. Impacts of diverted freshwater on dissolved organic matter and microbial communities in Barataria Bay, Louisiana, U.S.A.

    PubMed

    Bianchi, Thomas S; Cook, Robert L; Perdue, E Michael; Kolic, Paulina E; Green, Nelson; Zhang, Yaoling; Smith, Richard W; Kolker, Alexander S; Ameen, Alex; King, Gary; Ojwang, Loice M; Schneider, Caroline L; Normand, Anna E; Hetland, Robert

    2011-12-01

    Here we present results of an initial assessment of the impacts of a water diversion event on the concentrations and chemical composition of dissolved organic matter (DOM) and bacterioplankton community composition in Barataria Bay, Louisiana U.S.A, an important estuary within the Mississippi River Delta complex. Concentrations and spectral properties of DOM, as reflected by UV/visible absorbance and fluorescence, were strikingly similar at 26 sites sampled along transects near two western and two eastern areas of Barataria Bay in July and September 2010. In September 2010, dissolved organic carbon (DOC) was significantly higher (568.1-1043 μM C, x=755.6+/-117.7 μM C, n=14) than in July 2010 (249.1-577.1 μM C, x=383.7+/-98.31 μM C, n=14); conversely, Abs254 was consistently higher at every site in July (0.105-0.314) than in September (0.080-0.221), averaging 0.24±0.06 in July and 0.15±0.04 in September. Fluorescence data via the fluorescence index (FI450/500) revealed that only 30% (8 of 26) of the July samples had an FI450/500 above 1.36, compared to 96% (25 of 26) for the September samples. This indicates a more terrestrial origin for the July DOM. Bacterioplankton from eastern sites differed in composition from bacterioplankon in western sites in July. These differences appeared to result from reduced salinities caused by the freshwater diversion. Bacterioplankton communities in September differed from those in July, but no spatial structure was observed. Thus, the trends in bacterioplankton and DOM were likely due to changes in water masses (e.g., input of Mississippi River water in July and a return to estuarine waters in September). Discharge of water from the Davis Pond Freshwater Diversion (DPFD) through Barataria Bay may have partially mitigated some adverse effects of the oil spill, inasmuch as DOM is concerned.

  1. Benthic macrofauna productivity enhancement by an artificial reef in Delaware Bay, USA

    SciTech Connect

    Steimle, F; Foster, Karen L.; Kropp, Roy K.; Conlin, B

    2002-10-15

    To understand the potential enhancement value of a habitat-loss mitigation reef in Delaware Bay, especially as a source of food for fishery resources, the secondary productivity of the reef epifauna and nearby sand infauna was estimated and compared. The mean production of natural sand infauna was estimated at between 215 and 249 kcal m(2) yr(-1), while that of the epifauna on the reef surfaces was between 3990 and 9555 kcal m(2) yr(-1). With the 36 m(2) footprint of a reef unit as a basis for comparison, the 407 m(2) of reef unit surface covering that footprint produced 1.62-3.89 X 10(6) kcal yr(-1) of epifauna compared with 7.74-8.96 X 10(3) kcal yr(-1) per footprint area for the adjacent sand infauna. There was, however, substantial annual variability in the productivity of the epifauna, based on the recruitment success of Mytilus edulis.

  2. A Radiocarbon Chronology of Hunter-Gatherer Occupation from Bodega Bay, California, USA

    SciTech Connect

    Kennedy, M A; Russell, A D; Guilderson, T P

    2005-04-27

    The evolution of hunter-gatherer maritime adaptations in western North America has been a prominent topic of discussion among archaeologists in recent years (e.g. Arnold 1992; Erlandson and Colten 1991; Erlandson and Glassow 1997; Lightfoot 1993). Although vast coastal regions of the northeastern Pacific (for example, southern California) have been investigated in detail, our understanding of hunter-gatherer developments along the coast of northern California is limited. Previous research indicates that humans have exploited marine mammals, fish and shellfish along the northern California shoreline since the early Holocene (Schwaderer 1992). By the end of the late Holocene, some groups remained year-round on the coast subsisting primarily on marine resources (e.g. Gould 1975; Hildebrandt and Levulett 2002). However, a paucity of well-dated cultural deposits has hindered our understanding of these developments, particularly during the early and middle Holocene. The lack of a long and reliable chronological sequence has restricted our interpretations of behavioral change, including the adaptive strategies (such as foraging, mobility and settlement) used by human foragers to colonize and inhabit the coastal areas of this region. These shortcomings have also hindered comparative interpretations with other coastal and inland regions in western North America. Here we present a Holocene radiocarbon chronology of hunter-gatherer occupation based on contemporaneous samples of charcoal and Mytilus californianus (California sea mussel) shell recovered from seven archaeological sites near Bodega Bay, California. A series of 127 {sup 14}C ages reveal a chronological sequence that spans from ca. 8940-110 cal BP (1{sigma}) (7890-160 {sup 14}C yr BP = charcoal; 8934-101 {sup 14}C yr BP = shell). As part of this sequence, we report new {sup 14}C dates from the stratified cave and open-air midden deposits at Duncan's Landing (CA-SON-348/H). In addition, we present {sup 14}C ages

  3. Influence of water allocation and freshwater inflow on oyster production: a hydrodynamic-oyster population model for Galveston Bay, Texas, USA.

    PubMed

    Powell, Eric N; Klinck, John M; Hofmann, Eileen E; McManus, Margaret A

    2003-01-01

    A hydrodynamic-oyster population model was developed to assess the effect of changes in freshwater inflow on oyster populations in Galveston Bay, Texas, USA. The population model includes the effects of environmental conditions, predators, and the oyster parasite, Perkinsus marinus, on oyster populations. The hydrodynamic model includes the effects of wind stress, river runoff, tides, and oceanic exchange on the circulation of the bay. Simulations were run for low, mean, and high freshwater inflow conditions under the present (1993) hydrology and predicted hydrologies for 2024 and 2049 that include both changes in total freshwater inflow and diversions of freshwater from one primary drainage basin to another. Freshwater diversion to supply the Houston metropolitan area is predicted to negatively impact oyster production in Galveston Bay. Fecundity and larval survivorship both decline. Mortality from Perkinsus marinus increases, but to a lesser extent. A larger negative impact in 2049 relative to 2024 originates from the larger drop in fecundity under that hydrology. Changes in recruitment and mortality, resulting in lowered oyster abundance, occur because the bay volume available for mixing freshwater input from the San Jacinto and Buffalo Bayou drainage basins that drain metropolitan Houston is small in comparison to the volume of Trinity Bay that presently receives the bulk of the bay's freshwater inflow. A smaller volume for mixing results in salinities that decline more rapidly and to a greater extent under conditions of high freshwater discharge.Thus, the decline in oyster abundance results from a disequilibrium between geography and salinity brought about by freshwater diversion. Although the bay hydrology shifts, available hard substrate does not. The simulations stress the fact that it is not just the well-appreciated reduction in freshwater inflow that can result in decreased oyster production. Changing the location of freshwater inflow can also

  4. The effect of fire on mercury cycling in the soils of forested watersheds: Acadia National Park, Maine, U.S.A

    USGS Publications Warehouse

    Amirbahman, A.; Ruck, P.L.; Fernandez, I.J.; Haines, T.A.; Kahl, J.S.

    2004-01-01

    This study compares mercury (Hg) and methylmercury (MeHg) distribution in the soils of two forested stream watersheds at Acadia National Park, Maine, U.S.A. Cadillac Brook watershed, which burned in 1947, has thin soils and predominantly deciduous vegetation. It was compared to the unburned Hadlock Brook watershed, with thicker soil and predominantly coniferous vegetation. Soils in both watersheds were primarily well drained. The fire had a significant impact on the Cadillac watershed, by raising the soil pH, altering the vegetation, and reducing carbon and Hg pools. Total Hg content was significantly higher (P < 0.05) in Hadlock soils (0.18 kg Hg ha-1) compared to Cadillac soils (0. 13 kg Hg ha-1). Hadlock O horizon had an average Hg concentration of 134??48 ng Hg g-1 dry weight, compared to 103??23 ng Hg g-1 dry weight in Cadillac O horizon. Soil pH was significantly higher in all soil horizons at Cadillac compared to Hadlock soils. This difference was especially significant in the O horizon, where Cadillac soils had an average pH of 3.41??0.22 compared to Hadlock soils with an average pH of 2.99??0.13. To study the mobilization potential of Hg in the O horizons of the two watersheds, batch adsorption experiments were conducted, and the results were modeled using surface complexation modeling. The results of Hg adsorption experiments indicated that the dissolved Hg concentration was controlled by the dissolved organic carbon (DOC) concentration. The adsorption isotherms suggest that Hg is more mobile in the O horizon of the unburned Hadlock watershed because of higher solubility of organic carbon resulting in higher DOC concentrations in that watershed. Methylmercury concentrations, however, were consistently higher in the burned Cadillac O horizon (0.20??0.13 ng Hg g-1 dry weight) than in the unburned Hadlock O horizon (0.07??0.07 ng Hg g-1 dry weight). Similarly, Cadillac soils possessed a higher MeHg content (0.30 g MeHg ha-1) than Hadlock soils (0.16 g Me

  5. Application of geologic map information to water quality issues in the southern part of the Chesapeake Bay watershed, Maryland and Virginia, eastern United States

    USGS Publications Warehouse

    McCartan, L.; Peper, J.D.; Bachman, L.J.; Horton, J.W.

    1999-01-01

    Geologic map units contain much information about the mineralogy, chemistry, and physical attributes of the rocks mapped. This paper presents information from regional-scale geologic maps in Maryland and Virginia, which are in the southern part of the Chesapeake Bay watershed in the eastern United States. The geologic map information is discussed and analyzed in relation to water chemistry data from shallow wells and stream reaches in the area. Two environmental problems in the Chesapeake Bay watershed are used as test examples. The problems, high acidity and high nitrate concentrations in streams and rivers, tend to be mitigated by some rock and sediment types and not by others. Carbonate rocks (limestone, dolomite, and carbonate-cemented rocks) have the greatest capacity to neutralize acidic ground water and surface water in contact with them. Rocks and sediments having high carbon or sulfur contents (such as peat and black shale) potentially contribute the most toward denitrification of ground water and surface water in contact with them. Rocks and sediments that are composed mostly of quartz, feldspar, and light-colored clay (rocks such as granite and sandstone, sediments such as sand and gravel) tend not to alter the chemistry of waters that are in contact with them. The testing of relationships between regionally mapped geologic units and water chemistry is in a preliminary stage, and initial results are encouraging.Geologic map units contain much information about the mineralogy, chemistry, and physical attributes of the rocks mapped. This paper presents information from regional-scale geologic maps in Maryland and Virginia, which are in the southern part of the Chesapeake Bay watershed in the eastern United States. The geologic map information is discussed and analyzed in relation to water chemistry data from shallow wells and stream reaches in the area. Two environmental problems in the Chesapeake Bay watershed are used as test examples. The problems, high

  6. Report: EPA Relying on Existing Clean Air Act Regulations to Reduce Atmospheric Deposition to the Chesapeake Bay and its Watershed

    EPA Pesticide Factsheets

    Report #2007-P-00009, February 28, 2007. EPA’s Chesapeake Bay Program Office is relying on anticipated nitrogen deposition reductions from Clean Air Act (CAA) regulations already issued by EPA, combined with other non-air sources' anticipated reductions.

  7. Storm surges and climate change implications for tidal marshes: Insight from the San Francisco Bay Estuary, California, USA

    USGS Publications Warehouse

    Thorne, Karen M.; Buffington, Kevin J.; Swanson, Kathleen; Takekawa, John Y.

    2013-01-01

    Tidal marshes are dynamic ecosystems, which are influenced by oceanic and freshwater processes and daily changes in sea level. Projected sea-level rise and changes in storm frequency and intensity will affect tidal marshes by altering suspended sediment supply, plant communities, and the inundation duration and depth of the marsh platform. The objective of this research was to evaluate if regional weather conditions resulting in low-pressure storms changed tidal conditions locally within three tidal marshes. We hypothesized that regional storms will increase sea level heights locally, resulting in increased inundation of the tidal marsh platform and plant communities. Using site-level measurements of elevation, plant communities, and water levels, we present results from two storm events in 2010 and 2011 from the San Francisco Bay Estuary (SFBE), California, USA. The January 2010 storm had the lowest recorded sea level pressure in the last 30 years for this region. During the storm episodes, the duration of tidal marsh inundation was 1.8 and 3.1 times greater than average for that time of year, respectively. At peak storm surges, over 65% in 2010 and 93% in 2011 of the plant community was under water. We also discuss the implications of these types of storms and projected sea-level rise on the structure and function of the tidal marshes and how that will impact the hydro-geomorphic processes and marsh biotic communities.

  8. Hydrologic, chemical, and isotopic characterization of two small watersheds on Catoctin Mountain, north-central Maryland, U.S.A.

    USGS Publications Warehouse

    Rice, Karen C.; Bricker, O.P.

    1993-01-01

    Two small (100 ha) watersheds located on Catoctin Mountain in north-central Maryland were intensively instrumented in 1990 and have been hydrologically, chemically, and isotopically monitored for 3 years. Dissolved concentrations of major ions (Ca2+, Mg2+, Na+, K+, total AI, CI-, NO3-, SO42- , HCO3-, and SiO2) and stable isotopic (D and 18O) values have been analyzed for most types of water (precipitation, throughfall, two depths of soil water, shallow groundwater, and streamwater) that enter, travel through, and exit each watershed. The major objectives of the study were to characterize the chemical and isotopic signatures of all aqueous components of the watersheds and to interpret the causes of the changes in chemical and isotopic compositions of streamwater during storm runoff. This paper describes selected results of the study.

  9. Mesoscale geomorphic change on low energy barrier islands in Chesapeake Bay, U.S.A.

    NASA Astrophysics Data System (ADS)

    Cooper, J. Andrew G.

    2013-10-01

    This paper presents an analysis of decadal (mesoscale) geomorphic change on sandy barrier islands in the fetch-limited environment of Chesapeake Bay. Low energy barrier islands exist in two settings: on the fringe of marshes and in open water and this analysis shows the various types of barrier island to be genetically related. Barrier islands that face the dominant wind and wave direction (E or W) retreat via barrier translation, preserving the barrier island volume. Those that exist in re-entrants are dominated by longshore transport processes, are strongly affected by sediment supply and are subject to disintegration. Marsh fringe barrier islands are perched on or draped over the surface of the underlying marsh. They migrate landwards via barrier translation during periodic high water events accompanied by large waves (hurricanes and northeasters). The underlying marsh surface erodes under all water levels and the rate of retreat of the barrier island and underlying marsh may take place at different rates, leading to various configurations from perched barrier islands several metres landward of the marsh edge, to barrier islands that have a sandy shoreface extending into the subtidal zone. The coastal configuration during landward retreat of marsh fringe barrier islands is subject to strong local control exerted by the underyling marsh topography. As erosion of marsh promontories occurs and marsh creeks are intersected and bypassed, the configuration is subject to rapid change. Periodic sediment influxes cause spits to develop at re-entrants in the marsh. The spits are initiated as extensions of adjacent marsh fringe barrier islands, but as the sediment volume is finite, the initial drift-aligned spits become sediment-starved and begin to develop a series of swash-aligned cells as they strive for morphodynamic equilibrium. The individual cells are stretched until breaches form in the barrier islands, creating inlets with tidal deltas. At this stage the low

  10. Helium systematics of cold seep fluids at Monterey Bay, California, USA: Temporal variations and mantle contributions

    NASA Astrophysics Data System (ADS)

    Füri, E.; Hilton, D. R.; Brown, K. M.; Tryon, M. D.

    2009-08-01

    We report helium isotope ratios (3He/4He) as well as helium and neon abundance results for submarine cold seep fluids from Extrovert Cliff in Monterey Bay, California. Samples were collected in copper tubing attached to submarine flux meters operating in continuous pumping mode. Following instrumentation recovery, the tubing was sectioned to produce for the first time a high-resolution time series of dissolved He and Ne variations over a time span of several days. Noble gas concentrations are variable and appear affected by interaction with a hydrocarbon phase within the aquifer. However, it is still possible to resolve the He signal into components associated with air equilibration, excess air entrainment, and terrigenic fluxes (both crustal and mantle-derived). The mantle He contribution reaches ˜25-30% in some samples (up to 2.3 RA, where RA = air 3He/4He). Our quasi-continuous He-Ne record shows remarkable fluctuations over time scales of only a few hours and reflects the combined effects of gas stripping by hydrocarbons and an episodic input of mantle-derived fluids.

  11. Low prevalence of splenic mycobacteriosis in migratory striped bass Morone saxatilis from North Carolina and Chesapeake Bay, U.S.A.

    PubMed

    Matsche, Mark A; Overton, Anthony; Jacobs, John; Rhodes, Matt R; Rosemary, Kevin M

    2010-07-01

    Mycobacteriosis is a chronic bacterial disease causing an ongoing epizootic in striped bass Morone saxatilis in Chesapeake Bay, U.S.A. Prevalence of disease is high in pre-migratory fish, and multiple species of Mycobacterium spp. have been isolated. However, prevalence of mycobacteriosis in the coastal migratory population is unknown and is of concern to multiple coastal states, as disease-related mortality may impact the long-term health of the population. Histological examinations of spleens collected from fish caught by recreational anglers during the winter fishery in coastal North Carolina (2005-2006, n=249) and during the spring fishery in Chesapeake Bay (2006, n=120) indicated a low prevalence of mycobacteriosis (6.8% of all fish examined) in comparison to smaller, pre-migratory Chesapeake Bay fish. Genus-level PCR and subsequent sequencing of the 16-23S intergenic transcribed spacer (ITS) region revealed that all bacteria were phylogenetically related, but species is unknown. Location of survey, gender of fish, and total length of fish had no significant effect on prevalence of mycobacteriosis, parasitic granulomas, or the density of splenic granulomas (p > 0.05). These results may indicate that either granulomas resolve after Chesapeake Bay fish enter the coastal migratory population, or that there is disease-related mortality among pre-migratory Chesapeake Bay fish.

  12. Identifying sources of stream water sulfate after a summer drought in the Sleepers River watershed (Vermont, USA) using hydrological, chemical, and isotopic techniques

    USGS Publications Warehouse

    Mayer, B.; Shanley, J.B.; Bailey, S.W.; Mitchell, M.J.

    2010-01-01

    In many forested headwater catchments, peak SO42 - concentrations in stream water occur in the late summer or fall following drought potentially resulting in episodic stream acidification. The sources of highly elevated stream water SO42 - concentrations were investigated in a first order stream at the Sleepers River watershed (Vermont, USA) after the particularly dry summer of 2001 using a combination of hydrological, chemical and isotopic approaches. Throughout the summer of 2001 SO42 - concentrations in stream water doubled from ???130 to 270 ??eq/L while flows decreased. Simultaneously increasing Na+ and Ca2+ concentrations and ??34S values increasing from +7??? towards those of bedrock S (???+10.5???) indicated that chemical weathering involving hydrolysis of silicates and oxidation of sulfide minerals in schists and phyllites was the cause for the initial increase in SO42 - concentrations. During re-wetting of the watershed in late September and early October of 2001, increasing stream flows were accompanied by decreasing Na+ and Ca2+ concentrations, but SO42 - concentrations continued to increase up to 568 ??eq/L, indicating that a major source of SO42 - in addition to bedrock weathering contributed to peak SO42 - concentrations. The further increase in SO42 - concentrations coincided with an abrupt decrease of ??34S values in stream water SO42 - from maximum values near +10??? to minimum values near -3???. Soil investigations revealed that some C-horizons in the Spodsols of the watershed contained secondary sulfide minerals with ??34S values near -22???. The shift to negative ??34S values of stream water SO42 - indicates that secondary sulfides in C-horizons were oxidized to SO42 - during the particularly dry summer of 2001. The newly formed SO42 - was transported to the streams during re-wetting of the watershed contributing ???60% of the SO42 - during peak concentrations in the stream water. Thereafter, the contribution of SO42 - from oxidation of

  13. Some Challenges of an “Upside Down” Nitrogen Budget – Science and Management in Greenwich Bay, RI (USA)

    EPA Science Inventory

    When nutrients impact estuarine water quality, scientists and managers instinctively focus on quantifying and controlling land-based sources. However, in Greenwich Bay, RI, the estuary opens onto a larger and more intensively fertilized coastal water body (Narragansett Bay). Prev...

  14. A hybrid regional approach to model discharge at multiple sub-basins within the Calapooia Watershed, Oregon, USA

    EPA Science Inventory

    Modeling is a useful tool for quantifying ecosystem services and understanding their temporal dynamics. Here we describe a hybrid regional modeling approach for sub-basins of the Calapooia watershed that incorporates both a precipitation-runoff model and an indexed regression mo...

  15. IDENTIFICATION EFFICIENCY IN GROUNDWATER ADJACENT TO DITCHES WITHIN CONSTRUCTED RIPARIAN WETLANDS: KANKAKEE WATERSHED, ILLINOIS-INDIANA, U.S.A.

    EPA Science Inventory

    Dual isotope evaluations of NO3 in groundwater adjacent to ditches within constructed riparian wetlands across the Kankakee water-shed may assist the determination of denitrification efficiency. Groundwater sampling indicates the NO3 -N exceeded 10 mg 1-1 in constructed riparian ...

  16. Long-term trends in climate and hydrology in an agricultural headwater watershed of central Pennsylvania, USA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Climate change has emerged as a key issue facing agriculture and water resources in the US. Long-term (1968-2012) temperature, precipitation and streamflow data from a small (7.3 km2) watershed in east-central Pennsylvania was used to examine climatic and hydrologic trends in the context of recent c...

  17. Suspended sediment transport at the instantaneous and event time scales in semiarid watersheds of southeastern Arizona, USA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We investigated the high variability of suspended sediment transport in 16 watersheds of Walnut Gulch, southwestern United States that may be distinguished at three spatial scales: the plot (ca. 0.001 – 0.01 km2), unit-source (ca. 0.01 – 1 km2), and large (ca. 1 – 150 km2) scales. Event-based data...

  18. Sediment Budgets and Source Determinations Using Fallout Cesium-137 in a Semiarid Rangeland Watershed in Arizona, USA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Analysis of soil redistribution and sediment sources in semiarid and arid watersheds provides information for implementing management practices to improve rangeland conditions and reduce sediment loads to streams. The purpose of this research was to develop sediment budgets and to identify potentia...

  19. Geologic and environmental characteristics of porphyry copper deposits with emphasis on potential future development in the Bristol Bay Watershed, Alaska

    USGS Publications Warehouse

    Seal, Robert R., II

    2012-01-01

    Pebble; Big Chunk is approximately 30 miles (48 km) north-northwest of Pebble; and Shotgun is approximately 110 miles (177 km) northwest of Pebble. The H and D Block prospects, west of Pebble, represent additional porphyry copper exploration targets in the watershed.

  20. Storm erosion during the past 2000 years along the north shore of Delaware Bay, USA

    NASA Astrophysics Data System (ADS)

    Nikitina, Daria L.; Kemp, Andrew C.; Horton, Benjamin P.; Vane, Christopher H.; van de Plassche, Orson; Engelhart, Simon E.

    2014-03-01

    The recent impacts of tropical cyclones and severe storms on the U.S. Atlantic coast brought into focus the need for extended records of storm activity from different geomorphologic settings. Such reconstructions are typically developed from sites that experienced repeated overwash of sand into low-energy, depositional environments. However, salt-marsh sediment may also preserve a record of repeated erosion from tropical cyclones and storms. We describe late Holocene sediments beneath the Sea Breeze salt marsh (Delaware Bay, New Jersey) from more than 200 gouge cores positioned along seven transects. The stratigraphic record documents at least seven depositional sequences consisting of salt-marsh peat and mud couplets that represent dramatic changes in sedimentation regime. There are a number of processes that could produce these stratigraphic sequences against a background of rising relative sea level including: lateral migration of tidal creeks; tidal channel network and/or drainage ditch expansion; changes in sediment delivery rates; rapid relative sea-level change; tsunami; and formation of salt pans. The abrupt contacts between the salt-marsh peat and overlying intertidal mud suggest that erosion of the peat was followed by rapid infilling of accommodation space. Correlation of erosional surfaces across 2.5 km suggests a common mechanism and we propose that the erosion was caused by tropical cyclones and/or storms. We developed a chronology of repeated salt-marsh erosion and recovery using 137Cs, metal pollution (Pb concentration and stable isotopes), and radiocarbon data. Two recent episodes of salt-marsh erosion may correlate with historic tropical cyclones in AD 1903, and AD 1821/1788 that impacted the Atlantic coast of New Jersey, but the erosive nature of the Sea Breeze site hinders definitive correlation. Prehistoric erosional sequences correlate with overwash fans preserved in the regional sedimentary record. We estimated that it takes from several

  1. Origin and emplacement of impactites in the Chesapeake Bay impact structure, Virginia, USA

    USGS Publications Warehouse

    Horton, J.W.; Gohn, G.S.; Powars, D.S.; Edwards, L.E.

    2007-01-01

    The late Eocene Chesapeake Bay impact structure, located on the Atlantic margin of Virginia, may be Earth's best-preserved large impact structure formed in a shallow marine, siliciclastic, continental-shelf environment. It has the form of an inverted sombrero in which a central crater ???40 km in diameter is surrounded by a shallower brim, the annular trough, that extends the diameter to ???85 km. The annular trough is interpreted to have formed largely by the collapse and mobilization of weak sediments. Crystalline-clast suevite, found only in the central crater, contains clasts and blocks of shocked gneiss that likely were derived from the fragmentation of the central-uplift basement. The suevite and entrained megablocks are interpreted to have formed from impact-melt particles and crystalline-rock debris that never left the central crater, rather than as a fallback deposit. Impact-modified sediments in the annular trough include megablocks of Cretaceous nonmarine sediment disrupted by faults, fluidized sands, fractured clays, and mixed-sediment intercalations. These impact-modified sediments could have formed by a combination of processes, including ejection into and mixing of sediments in the water column, rarefaction-induced fragmentation and clastic injection, liquefaction and fluidization of sand in response to acoustic-wave vibrations, gravitational collapse, and inward lateral spreading. The Exmore beds, which blanket the entire crater and nearby areas, consist of a lower diamicton member overlain by an upper stratified member. They are interpreted as unstratified ocean-resurge deposits, having depositional cycles that may represent stages of inward resurge or outward anti-resurge flow, overlain by stratified fallout of suspended sediment from the water column. ?? 2008 The Geological Society of America. All rights reserved.

  2. Recent research on the Chesapeake Bay impact structure, USA - Impact debris and reworked ejecta

    USGS Publications Warehouse

    Horton, J.W.; Aleinikoff, J.N.; Kunk, M.J.; Gohn, G.S.; Edwards, L.E.; ,; Powars, D.S.; Izett, G.A.

    2005-01-01

    Four new coreholes in the western annular trough of the buried, late Eocene Chesapeake Bay impact structure provide samples of shocked minerals, cataclastic rocks, possible impact melt, mixed sediments, and damaged microfossils. Parautochthonous Cretaceous sediments show an upward increase in collapse, sand fluidization, and mixed sediment injections. These impact-modifi ed sediments are scoured and covered by the upper Eocene Exmore beds, which consist of highly mixed Cretaceous to Eocene sediment clasts and minor crystalline-rock clasts in a muddy quartz-glauconite sand matrix. The Exmore beds are interpreted as seawater-resurge debris flows. Shocked quartz is found as sparse grains and in rock fragments at all four sites in the Exmore, where these fallback remnants are mixed into the resurge deposit. Crystalline-rock clasts that exhibit shocked quartz or cataclastic fabrics include felsites, granitoids, and other plutonic rocks. Felsite from a monomict cataclasite boulder has a sensitive high-resolution ion microprobe U-Pb zircon age of 613 ?? 4 Ma. Leucogranite from a polymict cataclasite boulder has a similar Neoproterozoic age based on muscovite 40Ar/39Ar data. Potassium-feldspar 40Ar/39Ar ages from this leucogranite show cooling through closure (???150 ??C) at ca. 261 Ma without discernible impact heating. Spherulitic felsite is under investigation as a possible impact melt. Types of crystalline clasts, and exotic sediment clasts and grains, in the Exmore vary according to location, which suggests different provenances across the structure. Fractured calcareous nannofossils and fused, bubbled, and curled dinofl agellate cysts coexist with shocked quartz in the Exmore, and this damage may record conditions of heat, pressure, and abrasion due to impact in a shallow-marine environment. ?? 2005 Geological Society of America.

  3. Relation of lead exposure to sediment ingestion in mute swans on the Chesapeake Bay, USA

    USGS Publications Warehouse

    Beyer, W.N.; Day, D.; Morton, Alexandra; Pachepsky, Y.

    1998-01-01

    Forty-two mute swans (Cygnus olor ) were collected from unpolluted portions of central Chesapeake Bay in spring 1995. Their intestinal digesta were analyzed for 13 metals (Al, B, Ba, Cd, Cu, Fe, Mg, Mn, Ni, Pb, Sr, V, Zn) and for acid-insoluble ash, a marker of sediment. Because metal concentrations in digesta depend on recent exposure, they are appropriate for evaluating local contamination. Swan livers and sediment samples also were analyzed for the same metals. Group method of data handling demonstrated that the digesta Al was the best predictor of digesta Pb, and that adding concentrations of other metals as predictors did not improve the accuracy of the estimates of Pb concentrations from Al concentrations. The r2 of the equation relating the log of digesta Pb to the log of digesta Al was 0.86, whereas the r2 of the equation relating the log of digesta Pb to the log of digesta acid-insoluble ash was 0.50. Sediment ingestion was critical in determining exposure to Pb, as well as to some of the other metals, and should be considered in ecotoxicological risk assessments of waterfowl. The mean of 7.4% acid-insoluble ash in the digesta corresponded to an estimated 3.2% sediment in the diet. The Pb concentrations in the digesta were 2-3 times the concentration that would have been predicted from sediment Pb concentrations; presumably the swans had ingested clays high in Pb that had settled on the vegetation. The swans were not thought to have been exposed to high Cu concentrations but they had hepatic Cu concentrations that would be considered very high if found in other species.

  4. Above-ground sulfur cycling in adjacent coniferous and deciduous forest and watershed sulfur retention in the Georgia Piedmont, U.S.A.

    USGS Publications Warehouse

    Cappellato, R.; Peters, N.E.; Meyers, T.P.

    1998-01-01

    Atmospheric deposition and above-ground cycling of sulfur (S) were evaluated in adjacent deciduous and coniferous forests at the Panola Mountain Research Watershed (PMRW), Georgia U.S.A. Total atmospheric S deposition (wet plus dry) was 12.9 and 12.7 kg ha-1 yr-1 for the deciduous and coniferous forests, respectively, from October 1987 through November 1989. Dry deposition contributes more than 40% to the total atmospheric S deposition, and SO2 is the major source (~55%) of total dry S deposition. Dry deposition to these canopies is similar to regional estimates suggesting that 60-km proximity to emission sources does not noticeably impact dry deposition at PMRW. Below-canopy S fluxes (throughfall plus stemflow) in each forest are 37% higher annually in the deciduous forest than in the coniferous forest. An excess in below-canopy S flux in the deciduous forest is attributed to leaching and higher dry deposition than in the coniferous forest. Total S deposition to the forest floor by throughfall, stemflow and litterfall was 2.4 and 2.8 times higher in the deciduous and coniferous forests, respectively, than annual S growth requirement for foliage and wood. Although A deposition exceeds growth requirement, more than 95% of the total atmospheric S deposition was retained by the watershed in 1988 and 1989. The S retention at PMRW is primarily due to SO2+4 adsorption by iron oxides and hydroxides in watershed soils. The S content in while oak and loblolly pine boles have increased more than 200% in the last 20 yr, possibly reflecting increases in emissions.

  5. Acid-base characteristics of the Grass Pond watershed in the Adirondack Mountains of New York State, USA: interactions among soil, vegetation and surface waters

    NASA Astrophysics Data System (ADS)

    McEathron, K. M.; Mitchell, M. J.; Zhang, L.

    2013-07-01

    Grass Pond watershed is located within the southwestern Adirondack Mountain region of New York State, USA. This region receives some of the highest rates of acidic deposition in North America and is particularly sensitive to acidic inputs due to many of its soils having shallow depths and being generally base poor. Differences in soil chemistry and tree species between seven subwatersheds were examined in relation to acid-base characteristics of the seven major streams that drain into Grass Pond. Mineral soil pH, stream water BCS (base-cation surplus) and pH exhibited a positive correlation with sugar maple basal area (p = 0.055; 0.48 and 0.39, respectively). Black cherry basal area was inversely correlated with stream water BCS, ANC (acid neutralizing capacity)c and NO3- (p = 0.23; 0.24 and 0.20, respectively). Sugar maple basal areas were positively associated with watershed characteristics associated with the neutralization of atmospheric acidic inputs while in contrast, black cherry basal areas showed opposite relationships to these same watershed characteristics. Canonical correspondence analysis indicated that black cherry had a distinctive relationship with forest floor chemistry apart from the other tree species, specifically a strong positive association with forest floor NH4, while sugar maple had a distinctive relationship with stream chemistry variables, specifically a strong positive association with stream water ANCc, BCS and pH. Our results provide evidence that sugar maple is acid-intolerant or calciphilic tree species and also demonstrate that black cherry is likely an acid-tolerant tree species.

  6. 76 FR 2085 - National Estuarine Research Reserve System; North Inlet-Winyah Bay, SC and San Francisco Bay, CA...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-12

    ... support of the Bay's growing population: Climate change, species interactions, water quality, and habitat...- Winyah Bay such as impacts from coastal and watershed development, climate events on coastal...

  7. Sediment and discharge yields within a minimally disturbed, headwater watershed in North Central Pennsylvania, USA, with an emphasis on Superstorm Sandy

    USGS Publications Warehouse

    Maloney, Kelly O.; Shull, Dustin R.

    2015-01-01

    We estimated discharge and suspended sediment (SS) yield in a minimally disturbed watershed in North Central Pennsylvania, USA, and compared a typical storm (September storm, 4.80 cm) to a large storm (Superstorm Sandy, 7.47 cm rainfall). Depending on branch, Sandy contributed 9.7–19.9 times more discharge and 11.5–37.4 times more SS than the September storm. During the September storm, the upper two branches accounted for 60.6% of discharge and 88.8% of SS at Lower Branch; during Sandy these percentages dropped to 36.1% for discharge and 30.1% for SS. The branch with close proximity roads had over two-three times per area SS yield than the branch without such roads. Hysteresis loops showed typical clockwise patterns for the September storm and more complicated patterns for Sandy, reflecting the multipeak event. Estimates of SS and hysteresis in minimally disturbed watersheds provide useful information that can be compared spatially and temporally to facilitate management.

  8. The simulated effects of wastewater-management actions on the hydrologic system and nitrogen-loading rates to wells and ecological receptors, Popponesset Bay Watershed, Cape Cod, Massachusetts

    USGS Publications Warehouse

    Walter, Donald A.

    2013-01-01

    The discharge of excess nitrogen into Popponesset Bay, an estuarine system on western Cape Cod, has resulted in eutrophication and the loss of eel grass habitat within the estuaries. Septic-system return flow in residential areas within the watershed is the primary source of nitrogen. Total Maximum Daily Loads (TMDLs) for nitrogen have been assigned to the six estuaries that compose the system, and local communities are in the process of implementing the TMDLs by the partial sewering, treatment, and disposal of treated wastewater at wastewater-treatment facilities (WTFs). Loads of waste-derived nitrogen from both current (1997–2001) and future sources can be estimated implicitly from parcel-scale water-use data and recharge areas delineated by a groundwater-flow model. These loads are referred to as “instantaneous” loads because it is assumed that the nitrogen from surface sources is delivered to receptors instantaneously and that there is no traveltime through the aquifer. The use of a solute-transport model to explicitly simulate the transport of mass through the aquifer from sources to receptors can improve implementation of TMDLs by (1) accounting for traveltime through the aquifer, (2) avoiding limitations associated with the estimation of loads from static recharge areas, (3) accounting more accurately for the effect of surface waters on nitrogen loads, and (4) determining the response of waste-derived nitrogen loads to potential wastewater-management actions. The load of nitrogen to Popponesset Bay on western Cape Cod, which was estimated by using current sources as input to a solute-transport model based on a steady-state flow model, is about 50 percent of the instantaneous load after about 7 years of transport (loads to estuary are equal to loads discharged from sources); this estimate is consistent with simulated advective traveltimes in the aquifer, which have a median of 5 years. Model-calculated loads originating from recharge areas reach 80

  9. Narragansett Bay

    EPA Science Inventory

    Narragansett Bay, situated on the eastern side of Rhode Island, comprises about 15% of the State’s total area. Ninety-five percent of the Bay’s surface area is in Rhode Island with the remainder in southeastern Massachusetts; 60% of the Bay’s watershed is in Massachusetts. At the...

  10. Commercially-cultured oysters (Crassostrea gigas) exert top-down control on intertidal pelagic resources in Willapa Bay, Washington, USA

    NASA Astrophysics Data System (ADS)

    Wheat, Elizabeth; Ruesink, Jennifer L.

    2013-08-01

    The capacity of filter feeders to reduce seston and phytoplankton concentrations in the water column has important implications for restoration and management of coastal ecosystems. We directly measured changes in chlorophyll a concentration on commercially stocked intertidal oyster beds (Crassostrea gigas) in Willapa Bay, Washington, USA by recording water properties near small drifters as they tracked parcels of water across tide flats. Chlorophyll declined 9.6% per half hour in water passing on-bottom adult oysters and 41% for longline adult oysters, whereas chlorophyll concentrations increased as water flowed across tide flats without adult oysters. Field filtration rates, which were fit to exponential declines in chlorophyll and accounted for oyster density and water depth, averaged 0.35 L g- 1 h- 1 (shucked dry weight) for on-bottom aquaculture and 0.73 L g- 1 h- 1 for longline culture, compared to values of 2.5-12 L g- 1 h- 1 reported from laboratory studies of C. gigas. Field filtration rates may be lower than laboratory rates due to unfavorable field conditions (e.g., low initial chlorophyll concentrations) or masked by resuspension of benthic microalgae. In addition to distinctions among on-bottom, longline, and no-oyster habitats, Akaike's Information Criterion analysis showed temperature, initial chlorophyll concentration, and depth related to chlorophyll decline. This research corroborates mathematical models suggesting that benthic suspension feeders are exerting top-down control of pelagic production in this estuary, with strong patterns in chlorophyll emerging across extensive tideflats populated by C. gigas despite low field filtration rates.

  11. Development of an Intelligent Digital Watershed to understand water-human interaction for a sustainable Agroeconomy in Midwest USA

    NASA Astrophysics Data System (ADS)

    Mishra, S. K.; Rapolu, U.; Ding, D.; Muste, M.; Bennett, D.; Schnoor, J. L.

    2011-12-01

    Human activity is intricately linked to the quality and quantity of water resources. Although many studies have examined water-human interaction, the complexity of such coupled systems is not well understood largely because of gaps in our knowledge of water-cycle processes which are heavily influenced by socio-economic drivers. Considerable research has been performed to develop an understanding of the impact of local land use decisions on field and catchment processes at an annual basis. Still less is known about the impact of economic and environmental outcomes on decision-making processes at the local and national level. Traditional geographic information management systems lack the ability to support the modeling and analysis of complex spatial processes. New frameworks are needed to track, query, and analyze the massive amounts of data generated by ensembles of simulations produced by multiple models that couple socioeconomic and natural system processes. On this context, we propose to develop an Intelligent Digital Watershed (IDW) which fuses emerging concepts of Digital Watershed (DW). DW is a comprehensive characterization of the eco hydrologic systems based on the best available digital data generated by measurements and simulations models. Prototype IDW in the form of a cyber infrastructure based engineered system will facilitate novel insights into human/environment interactions through multi-disciplinary research focused on watershed-related processes at multiple spatio-temporal scales. In ongoing effort, the prototype IDW is applied to Clear Creek watershed, an agricultural dominating catchment in Iowa, to understand water-human processes relevant to management decisions by farmers regarding agro ecosystems. This paper would also lay out the database design that stores metadata about simulation scenarios, scenario inputs and outputs, and connections among these elements- essentially the database. The paper describes the cyber infrastructure and

  12. Impacts of Deepwater Horizon Oil on Marsh Sediment Biogeochemistry in Barataria Bay, LA, USA

    NASA Astrophysics Data System (ADS)

    Mills, C. T.; Windham-Myers, L.; Waldrop, M. P.; Krabbenhoft, D. P.; Marvin-DiPasquale, M. C.; Orem, W. H.; Piazza, S.; Haw, M.; McFarland, J.; Varonka, M. S.

    2012-12-01

    Oil from the Deepwater Horizon spill came ashore on many salt marsh islands in Barataria Bay, LA in summer 2010, coating plants and settling on the sediment surface. In coordination with a plant community study of affected marshes, we investigated impacts of oiling on marsh sediment microbial biogeochemistry. Sediment samples (upmost 2 cm) were collected along transects perpendicular and parallel to the shore at three oiled and three non-oiled sites in both July and Oct. 2011. Samples from both collections were analyzed for sediment characteristics, total and methylmercury, and microbial membrane phospholipid fatty acids (PLFAs) which are a proxy for viable microbial cell numbers. Sediment DNA collected in Oct. 2011 was analyzed for bacterial, fungal, and archaeal community composition and abundance as well as various enzyme activities. Select Oct. 2011 samples were assayed to determine the rates of terminal electron accepting processes (oxygen demand, denitrification, iron reduction, sulfate reduction, methanogenesis). All sites had similar sediment characteristics. Impacts on sediment biogeochemistry were greatest at marsh edges, and reduced microbial abundance appeared to be more important than changes in microbial community structure. In July 2011, the mean PLFA concentration in oiled marsh edge sediments (0.15±0.03 μmol g-1; 95% CI; n=9) was substantially lower than for non-oiled sites (0.33±0.08 μmol g-1; n=9). Mean PLFA concentrations for interior marsh samples were more similar for oiled (0.30±0.08 μmol g-1; n=8) and non-oiled (0.37±0.04 μmol g-1; n=9) sites. This PLFA pattern was also observed in Oct. 2011 samples, and other measures of microbial abundance and activity showed similar trends. Cellulase, phosphatase, and chitinase mean activities were nearly twice as great in non-oiled versus oiled edge sites. Lower microbial activity in oiled sites was also inferred by somewhat lower denitrification and sulfate reduction potentials. Conversely, both

  13. Trace Element Distribution in Stream Bed Sediments Within AN Agricultural Catchment of the Broadkill River Watershed, Delaware, USA

    NASA Astrophysics Data System (ADS)

    Oyewumi, O.; Schreiber, M. E.

    2011-12-01

    This project examined the impact of long-term litter application on the chemical signatures of trace metals (As, Cu, Zn,) and nutrient (P) in river sediments of the Broadkill River watershed within the Delmarva Peninsula, a region of intense poultry production. Twenty-seven (27) sediment samples were collected from Broadkill River drainage systems and analyzed for acid and soluble extractable elements as well as basic soil parameters such as particle size, organic matter and soluble salts. Results showed that concentrations of the trace elements in stream sediments are approximately log-normally distributed, with concentrations increasing from upstream headwaters to downstream reaches draining predominantly agricultural areas. Using GIS maps with overlays of hydrology and land use activity, correlations between the concentrations of As, Cu, Zn and P and agricultural activities within the watershed were examined. Results indicate positive correlation between the trace elements but the connection to specific regions of agricultural land use is not clearly defined. Trace elements were also positively correlated with percent of clay and silt particles, indicating partitioning of these elements to finer grain sizes. Calculations of element enrichment factors and the geoaccumulation index revealed that most of the sediment samples were not enriched in trace elements with respect to our reference samples. However, trace element concentrations in sediments increased downgradient, suggesting that they may be influenced by anthropogenic activities within the watershed.

  14. Biological response signature of oil brine threats, sediment contaminants, and crayfish assemblages in an Indiana watershed, USA.

    PubMed

    Simon, Thomas P; Morris, Charles C

    2009-01-01

    The Patoka River watershed contains a divergent landscape of oil and gas exploration, intensive agriculture, and surface mining mixed with National Forest, Wildlife Refuges, and a large recreational reservoir. We evaluated species diversity among different land uses, including, commercial, forested, residential, and agriculture, and determined relationships among disturbance scale, habitat requirements, contaminants, and patterns in species distributions. Primary burrowing species, Cambarus polychromatus, Cambarus cf diogenes (Lacunicambarus A), and Fallicambarus fodiens, were tolerant of higher concentrations of contaminants than aquatic tertiary burrowing species. Cambarus polychromatus was among the last species of crayfish at the most disturbed sites, while it was absent from pasture and agricultural landscapes that allowed cattle access along banks. Four species of Orconectes were found in the reference and agricultural landscapes within the watershed, including O. immunis, O. indianensis, O. inermis inermis, and O. propinquus. Orconectes indianensis distribution was determined by the presence of rock habitat and absence of contaminants. No Orconectes species were found in acid mine leachate-affected streams with high levels of molybdenum. Cambarus laevis was found in the highest-quality reference areas, which were associated with karst habitats and no contaminants. Burrowing crayfish species were associated with the oil derricks in the lower and middle watershed, which contained increased concentrations of strontium, phosphorus, and various organic parameters associated with oil brine PAHs.

  15. Heavy-mineral provenance in an estuarine environment, Willapa Bay, Washington, USA: palaeogeographic implications and estuarine evolution

    USGS Publications Warehouse

    Luepke Bynum, Gretchen

    2007-01-01

    Modern sediments from representative localities in Willapa Bay, Washington, comprise two principal heavy-mineral suites. One contains approximately equivalent amounts of hornblende, orthopyroxene, and clinopyroxene; this is derived from the Columbia River, which discharges into the Pacific Ocean a short distance south of the bay. The other suite, dominated by clinopyroxene, is restricted to sands of rivers flowing into the bay from the east. The heavy-mineral distributions within the bay suggest that sand discharged from the Columbia River, borne north by longshore transport and carried into the bay by tidal currents, accounts for nearly all of the sand within the interior of Willapa Bay today. Pleistocene deposits on the east side of the bay contain three heavy-mineral assemblages, two of which are identical to the modern assemblages described above. These assemblages reflect the relative influence of tidal and fluvial processes on the Late Pleistocene deposits (100,000–200,000 BP. Amino acid racemization in Quaternary shell deposits at Willapa Bay, Washington. Geochimica et Cosmochimica Acta 43, 1505–1520). They are also consistent with those processes inferred on the basis of sedimentary structures and stratigraphic relations in about two-thirds of the samples examined. Anomalies can be explained by recycling of sand from older deposits. The persistence of the two heavy-mineral suites suggests that the pattern of estuarine sedimentation in Late Pleistocene deposits closely resembled that of the modern bay. The third heavy-mineral suite is enriched in epidote and occurs in a few older Pleistocene units. On the north side of the bay, the association of this suite with southwest-directed foresets in cross-bedded gravel indicates derivation from the northeast, perhaps from an area of glacial outwash. The presence of this suite in ancient estuarine sands exposed on the northeast side of the bay suggests that input from this northerly source may have

  16. Hydrogeological impacts of road salt from Canada's busiest highway on a Lake Ontario watershed (Frenchman's Bay) and lagoon, City of Pickering.

    PubMed

    Meriano, Mandana; Eyles, Nick; Howard, Ken W F

    2009-06-26

    The quantity of deicing salt applied to paved surfaces in urban watersheds in cold regions has had a significant and cumulative effect on groundwater quality. Whereas road deicing salt is known in general to impact groundwater and surface water quality, quantitative information on the impact of large transport routes is lacking. In this study, we provide a chloride mass balance for an urban stream crossed by a large transport route in south-central Ontario, Canada and quantify likely long-term impacts of salt loading on surface and groundwater resources. The chloride mass balance, supported by hydrochemical analysis, reveals that approximately 50% of the total road salt applied to Pine Creek (1700 tonnes per winter) is removed annually via overland flow with the remainder accumulating in the shallow subsurface resulting in severe degradation of groundwater quality. Moreover, results show that road salt migration is the primary reason for enhanced mineral weathering in the shallow aquifer. During the 2004-05 salting season, runoff and baseflow transport of road salts were responsible for chloride concentrations in the stream of up to 2000 mg L(-1), and delivered approximately 850 tonnes of chloride (about 1400 tonnes of salt) to a shallow (<3.5 m) semi-enclosed lagoon on the shore of Lake Ontario (Frenchman's Bay; 0.85 km(2)). The total chloride delivery to the lagoon from its entire watershed is estimated at 3700 tonnes each year with up to 48% of the total load delivered by baseflow, the remainder from surface water runoff. Present day groundwater chloride concentrations are estimated to be about 80% of long-term concentrations when the system reaches steady state.

  17. The Stream-Catchment (StreamCat) Dataset: A database of watershed metrics for the conterminous USA

    EPA Science Inventory

    We developed an extensive database of landscape metrics for ~2.65 million streams, and their associated catchments, within the conterminous USA: The Stream-Catchment (StreamCat) Dataset. These data are publically available and greatly reduce the specialized geospatial expertise n...

  18. Nitrogen retention in rivers: Model development and application to watersheds in the northeastern U.S.A.

    USGS Publications Warehouse

    Seitzinger, S.P.; Styles, R.V.; Boyer, E.W.; Alexander, R.B.; Billen, G.; Howarth, R.W.; Mayer, B.; Van Breemen, N.

    2002-01-01

    A regression model (RivR-N) was developed that predicts the proportion of N removed from streams and reservoirs as an inverse function of the water displacement time of the water body (ratio of water body depth to water time of travel). When applied to 16 drainage networks in the eastern U.S., the RivR-N model predicted that 37% to 76% of N input to these rivers is removed during transport through the river networks. Approximately half of that is removed in 1st through 4th order streams which account for 90% of the total stream length. The other half is removed in 5th order and higher rivers which account for only about 10% of the total stream length. Most N removed in these higher orders is predicted to originate from watershed loading to small and intermediate sized streams. The proportion of N removed from all streams in the watersheds (37-76%) is considerably higher than the proportion of N input to an individual reach that is removed in that reach (generally <20%) because of the cumulative effect of continued nitrogen removal along the entire flow path in downstream reaches. This generally has not been recognized in previous studies, but is critical to an evaluation of the total amount of N removed within a river network. At the river network scale, reservoirs were predicted to have a minimal effect on N removal. A fairly modest decrease (<10 percentage points) in the N removed at the river network scale was predicted when a third of the direct watershed loading was to the two highest orders compared to a uniform loading.

  19. Soil erosion and sediment fluxes analysis: a watershed study of the Ni Reservoir, Spotsylvania County, VA, USA.

    PubMed

    Pope, Ian C; Odhiambo, Ben K

    2014-03-01

    Anthropogenic forces that alter the physical landscape are known to cause significant soil erosion, which has negative impact on surface water bodies, such as rivers, lakes/reservoirs, and coastal zones, and thus sediment control has become one of the central aspects of catchment management planning. The revised universal soil loss equation empirical model, erosion pins, and isotopic sediment core analyses were used to evaluate watershed erosion, stream bank erosion, and reservoir sediment accumulation rates for Ni Reservoir, in central Virginia. Land-use and land cover seems to be dominant control in watershed soil erosion, with barren land and human-disturbed areas contributing the most sediment, and forest and herbaceous areas contributing the least. Results show a 7 % increase in human development from 2001 (14 %) to 2009 (21.6 %), corresponding to an increase in soil loss of 0.82 Mg ha(-1) year(-1) in the same time period. (210)Pb-based sediment accumulation rates at three locations in Ni Reservoir were 1.020, 0.364, and 0.543 g cm(-2) year(-1) respectively, indicating that sediment accumulation and distribution in the reservoir is influenced by reservoir configuration and significant contributions from bedload. All three locations indicate an increase in modern sediment accumulation rates. Erosion pin results show variability in stream bank erosion with values ranging from 4.7 to 11.3 cm year(-1). These results indicate that urban growth and the decline in vegetative cover has increased sediment fluxes from the watershed and poses a significant threat to the long-term sustainability of the Ni Reservoir as urbanization continues to increase.

  20. Inferring Process Changes from 30 Years of Distributed Mountain Snowfall and Measured Streamflow at Reynolds Creek Experimental Watershed, Idaho, USA.

    NASA Astrophysics Data System (ADS)

    Kormos, P. R.; Marks, D. G.; Seyfried, M. S.; Havens, S.; Hedrick, A. R.; Garen, D. C.; Pierson, F. B.

    2015-12-01

    The hydrologic system in snowy mountain catchments includes complicated linkages and feedbacks between climate, snow cover, transpiring vegetation, and streamflow. We use 30 water years (1984 - 2014) of precipitation, relative humidity, air temperature, and streamflow data to identify changes that have occurred in the Reynolds Creek Experimental Watershed in Idaho. The process changes that have occurred during this time are presented and analyzed. This unique spatially distributed data set clearly highlights the transition from snow to rain in mountain regions of western North America.

  1. Developing a post-fire flood chronology and recurrence probability from alluvial stratigraphy in the Buffalo Creek watershed, Colorado, USA

    NASA Astrophysics Data System (ADS)

    Elliott, John G.; Parker, R. S.

    2001-10-01

    Stratigraphic and geomorphic evidence indicate floods that occur soon after forest fires have been intermittent but common events in many mountainous areas during the past several thousand years. The magnitude and recurrence of these post-fire flood events reflects the joint probability between the recurrence of fires and the recurrence of subsequent rainfall events of varying magnitude and intensity. Following the May 1996 Buffalo Creek, Colorado, forest fire, precipitation amounts and intensities that generated very little surface runoff outside of the burned area resulted in severe hillslope erosion, floods, and streambed sediment entrainment in the rugged, severely burned, 48 km2 area. These floods added sediment to many existing alluvial fans, while simultaneously incising other fans and alluvial deposits. Incision of older fans revealed multiple sequences of fluvially transported sandy gravel that grade upward into charcoal-rich, loamy horizons. We interpret these sequences to represent periods of high sediment transport and aggradation during floods, followed by intervals of quiescence and relative stability in the watershed until a subsequent fire occurred.An alluvial sequence near the mouth of a tributary draining a 0·82 km2 area indicated several previous post-fire flood cycles in the watershed. Dendrochronologic and radiocarbon ages of material in this deposit span approximately 2900 years, and define three aggradational periods. The three general aggradational periods are separated by intervals of approximately nine to ten centuries and reflect a millennium-scale geomorphic response to a closely timed sequence of events: severe and intense, watershed-scale, stand-replacing fires and subsequent rainstorms and flooding. Millennium-scale aggradational units at the study site may have resulted from a scenario in which the initial runoff from the burned watershed transported and deposited large volumes of sediment on downstream alluvial surfaces and

  2. Developing a post-fire flood chronology and recurrence probability from alluvial stratigraphy in the Buffalo Creek watershed, Colorado, USA

    USGS Publications Warehouse

    Elliott, J.G.; Parker, R.S.

    2001-01-01

    Stratigraphic and geomorphic evidence indicate floods that occur soon after forest fires have been intermittent but common events in many mountainous areas during the past several thousand years. The magnitude and recurrence of these post-fire flood events reflects the joint probability between the recurrence of fires and the recurrence of subsequent rainfall events of varying magnitude and intensity. Following the May 1996 Buffalo Creek, Colorado, forest fire, precipitation amounts and intensities that generated very little surface runoff outside of the burned area resulted in severe hillslope erosion, floods, and streambed sediment entrainment in the rugged, severely burned, 48 km2 area. These floods added sediment to many existing alluvial fans, while simultaneously incising other fans and alluvial deposits. Incision of older fans revealed multiple sequences of fluvially transported sandy gravel that grade upward into charcoal-rich, loamy horizons. We interpret these sequences to represent periods of high sediment transport and aggradation during floods, followed by intervals of quiescence and relative stability in the watershed until a subsequent fire occurred. An alluvial sequence near the mouth of a tributary draining a 0??82 km2 area indicated several previous post-fire flood cycles in the watershed. Dendrochronologic and radiocarbon ages of material in this deposit span approximately 2900 years, and define three aggradational periods. The three general aggradational periods are separated by intervals of approximately nine to ten centuries and reflect a 'millennium-scale' geomorphic response to a closely timed sequence of events: severe and intense, watershed-scale, stand-replacing fires and subsequent rainstorms and flooding. Millennium-scale aggradational units at the study site may have resulted from a scenario in which the initial runoff from the burned watershed transported and deposited large volumes of sediment on downstream alluvial surfaces and

  3. A Watershed Scale Numerical Model of the Impact of Land Use Change on Bed Material Transport in Suburban Maryland, USA

    NASA Astrophysics Data System (ADS)

    Lewicki, M.; Pizzuto, J. E.

    2005-12-01

    We have developed a numerical model for routing bedload through channel networks. The model treats the network as a series of connected reaches, with each reach being tens of channel widths in length. Processes represented within each reach include bank and bed erosion and deposition, bedload inputs from upstream, and bedload transport out of the reach. The rate of bank erosion is proportional to the percentage of the upstream watershed area under construction, and bank erosion supplies additional bedload to the reach. Inputs from upstream are assumed to be known, either as boundary conditions or from a previous computation at the adjacent upstream reach. The numerical model is intended to simulate the evolution of river channels in response to watershed scale changes in land use and climate change. The performance of the model has been evaluated, with satisfactory results, by comparing the simulated values and the measured data from studies that represent a watershed scale sediment budget, and a laboratory flume experiment. The field data used to evaluate the model comes from the Good Hope tributary, a second-order stream that is located in the Anacostia River watershed. Simulation with the model reproduced most of the major features of the field measurements, including sediment budget data and inferred patterns of erosion and deposition. In the Good Hope Tributary the streambed has in most cases responded to land use stress by longitudinal profile adjustment and grain size coarsening, especially in the 85th percentile. A version of the model without tributaries predicted increased bed erosion when compared with the network model. Comparison of the network and the single channel model results indicates limited to approximately 200 meters impact of lateral inputs of sediment from tributaries on grain size distribution of the main channel. Finally, numerical runs of the model simulating field conditions from 1952 to 2042 indicate that the river morphology is still

  4. Modeling the impacts of winter cover crops on water quality in two adjacent sub-watersheds within the Chesapeake Bay Watershed, Maryland, USA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Choptank River on Maryland’s Eastern Shore has been designated by the USEPA as “impaired waters” under Section 303(d) of the Federal Clean Water Act of 1972, mainly because of significant nutrient loads that resulted in not meeting the EPA water quality standards. This water quality deteriorati...

  5. Toxicity of chloride under winter low-flow conditions in an urban watershed in central Missouri, USA.

    PubMed

    Allert, Ann L; Cole-Neal, Cavelle L; Fairchild, James F

    2012-08-01

    Deicers such as sodium chloride and calcium chloride are used to treat snow and ice on road surfaces and have been identified as potential stressors on aquatic life. Hinkson Creek is an urban stream on the Missouri 303(d) list of impaired waters and is classified as impaired due to urban non-point source pollution. A 7-day toxicity test using Ceriodaphnia dubia was conducted to assess the toxicity of stream water during snowmelt at seven sites within the Hinkson Creek watershed. Chloride concentrations at two sites (Site 6, 1252 mg Cl/L; Site 4, 301 mg Cl/L) exceeded the U.S. Environmental Protection Agency chronic criterion (230 mg Cl/L). Survival (30 %) and total reproduction (6.9 young/adult) of C. dubia at Site 6 was significantly lower than survival (100 %) and total reproduction (30.4 young/adult) at Site 1 (reference site). Results indicate that chloride concentrations are elevated above water-quality criteria and that chloride may be a significant chemical stressor for macroinvertebrate communities during winter low-flow conditions in the Hinkson Creek watershed.

  6. Toxicity of chloride under winter low-flow conditions in an urban watershed in central Missouri, USA

    USGS Publications Warehouse

    Allert, Ann L.; Cole-Neal, Cavelle L.; Fairchild, James F.

    2012-01-01

    Deicers such as sodium chloride and calcium chloride are used to treat snow and ice on road surfaces and have been identified as potential stressors on aquatic life. Hinkson Creek is an urban stream on the Missouri 303(d) list of impaired waters and is classified as impaired due to urban non-point source pollution. A 7-day toxicity test using Ceriodaphnia dubia was conducted to assess the toxicity of stream water during snowmelt at seven sites within the Hinkson Creek watershed. Chloride concentrations at two sites (Site 6, 1252 mg Cl/L; Site 4, 301 mg Cl/L) exceeded the U.S. Environmental Protection Agency chronic criterion (230 mg Cl/L). Survival (30 %) and total reproduction (6.9 young/adult) of C. dubia at Site 6 was significantly lower than survival (100 %) and total reproduction (30.4 young/adult) at Site 1 (reference site). Results indicate that chloride concentrations are elevated above water-quality criteria and that chloride may be a significant chemical stressor for macroinvertebrate communities during winter low-flow conditions in the Hinkson Creek watershed.

  7. Evaluating process domains in small arid granitic watersheds: Case study of Pima Wash, South Mountains, Sonoran Desert, USA

    NASA Astrophysics Data System (ADS)

    Seong, Yeong Bae; Larson, Phillip H.; Dorn, Ronald I.; Yu, Byung Yong

    2016-02-01

    This paper provides support for the concept of geomorphic process domains developed by Montgomery (1999) by linking geomorphic processes to ecological variations seen in the Pima arid granitic watershed of the Sonoran Desert, Phoenix, Arizona. Closer joint spacing shows a statistically significant correlation with lower percentages of mineral grain attachment as measured by digital image processing of backscattered electron microscope imagery. Lower mineral grain attachment leads to more frequent spalling of rock surfaces, as measured by varnish microlamination (VML) ages of the last spalling event. In contrast, more distant joint spacing leads to in situ 10Be erosion rates of 3.4-8.5 mm/ka and the emergence of low domes and kopje granitic landforms; these low domes also serve as knickpoints along ephemeral washes. Distant jointing thus plays a key role in generating the bare bedrock surfaces that funnel limited precipitation to bedrock margins - enhancing the canopy cover of perennial plants next to the bare bedrock. Joint-influenced geomorphic processes at Pima Wash generate four distinct process domains: (PD1) armored drainage divides; (PD2) slopes with different granite landforms; (PD3) mid- and upper basin channels that mix knickzones, strath floodplains, and sandy alluvial sections; and (PD4) the main ephemeral channel transitioning to the piedmont. Distant jointing promotes bedrock exposure and rock armoring along drainage divides in PD1 that then concentrates runoff and promotes perennial plant growth. More distant joint spacing on slopes in PD2 promotes exposure of granitic bedrock forms that shed overland flow to their margin and promotes flora and fauna growths along the margins of low granitic domes and kopjes. Similarly, wider joint spacing along ephemeral washes in PD3 leads to knickpoints, which in turn act to concentrate moisture immediately downstream. The stream terraces in PD4 influence the ecology through xeric desert pavements on terrace treads

  8. ENVIRONMENTAL STRESS AND RECOVERY: THE GEOCHEMICAL RECORD OF HUMAN DISTURBANCE IN NEW BEDFORD HARBOR AND APPONAGANSETT BAY, MASSACHUSETTS (USA)

    EPA Science Inventory

    To restore and maintain chemical, physical, and biological integrity of the nation's waters, knowledge of the characteristics of unimpaired water bodies and their watersheds is required. The historical reconstruction approach of assessing ecological integrity uses records of hum...

  9. Impacts of Climate and Land-cover Changes on Water Resources in a Humid Subtropical Watershed: a Case Study from East Texas, USA

    NASA Astrophysics Data System (ADS)

    Heo, J.

    2015-12-01

    This study investigates an interconnected system of climate change - land cover - water resources for a watershed in humid subtropical climate from 1970 to 2009. A 0.7°C increase in temperature and a 16.3% increase in precipitation were observed in our study area where temperature had no obvious increase trend and precipitation showed definite increasing trend compared to previous studies. The main trend of land-cover change was conversion of vegetation and barren lands to developed and crop lands affected by human intervention, and forest and grass to bush/shrub which considered to be caused by natural climate system. Precipitation contribution to the other hydrologic parameters for a humid subtropical basin is estimated to be 51.9% of evapotranspiration, 16.3% of surface runoff, 0.9% of groundwater discharge, 19.3% of soil water content, and 11.6% of water storage. It shows little higher evapotranspiration and considerably lower surface runoff compare to other humid climate area due to vegetation dominance of land cover. Hydrologic responses to climate and land cover changes are increases of surface runoff, soil water content, evapotranspiration by 15.0%, 2.7%, and 20.1%, respectively, and decrease of groundwater discharge decreased by 9.2%. Surface runoff is relatively stable with precipitation while groundwater discharge and soil water content are sensitive to land cover changes especially human intervention. If temperature is relatively stable, it is considered to be land cover plays important role in evapotranspiration. Citation: Heo, J., J. Yu, J. R. Giardino, and H. Cho (2015), Impacts of climate and land-cover changes on water resources in a humid subtropical watershed: a case study from East Texas, USA, Water Environ. J., 29, doi:10.1111/wej.12096

  10. Effect of bedrock permeability on subsurface stormflow and the water balance of a trenched hillslope at the Panola Mountain Research Watershed, Georgia, USA

    USGS Publications Warehouse

    Tromp-van, Meerveld; Peters, N.E.; McDonnell, Jeffery J.

    2007-01-01

    The effect of bedrock permeability on subsurface stormflow initiation and the hillslope water balance is poorly understood. Previous hillslope hydrological studies at the Panola Mountain Research Watershed (PMRW), Georgia, USA, have assumed that the bedrock underlying the trenched hillslope is effectively impermeable. This paper presents a series of sprinkling experiments where we test the bedrock impermeability hypothesis at the PMRW. Specifically, we quantify the bedrock permeability effects on hillslope subsurface stormflow generation and the hillslope water balance at the PMRW. Five sprinkling experiments were performed by applying 882-1676 mm of rainfall over a ???5.5 m ?? 12 m area on the lower hillslope during ???8 days. In addition to water input and output captured at the trench, we measured transpiration in 14 trees on the slope to close the water balance. Of the 193 mm day-1 applied during the later part of the sprinkling experiments when soil moisture changes were small, 175 mm day-1 (91%). Bedrock moisture was measured at three locations downslope of the water collection system in the trench. Bedrock moisture responded quickly to precipitation in early spring. Peak tracer breakthrough in response to natural precipitation in the bedrock downslope from the trench was delayed only 2 days relative to peak tracer arrival in subsurface stormflow at the trench. Leakage to bedrock influences subsurface stormflow at the storm time-scale and also the water balance of the hillslope. This has important implications for the age and geochemistry of the water and thus how one models this hillslope and watershed. Copyright ?? 2006 John Wiley & Sons, Ltd.

  11. Exploring the nutrient inputs and cycles in Tampa Bay and coastal watersheds using MODIS images and data mining

    NASA Astrophysics Data System (ADS)

    Chang, Ni-Bin; Xuan, Zhemin

    2011-09-01

    Excessive nutrients, which may be represented as Total Nitrogen (TN) and Total Phosphorus (TP) levels, in natural water systems have proven to cause high levels of algae production. The process of phytoplankton growth which consumes the excess TN and TP in a water body can also be related to the changing water quality levels, such as Dissolved Oxygen (DO), chlorophyll-a, and turbidity, associated with their changes in absorbance of natural radiation. This paper explores spatiotemporal nutrient patterns in Tampa Bay, Florida with the aid of Moderate Resolution Imaging Spectroradiometer or MODIS images and Genetic Programming (GP) models that are deigned to link those relevant water quality parameters in aquatic environments.

  12. Alameda Creeks Healthy Watersheds Project

    EPA Pesticide Factsheets

    Information about the SFBWQP Alameda Creeks Healthy Watersheds Project, part of an EPA competitive grant program to improve SF Bay water quality focused on restoring impaired waters and enhancing aquatic resour

  13. Variability and Hysteresis in Streamwater Dissolved Organic Carbon during Hydrologic Events and its Implications on Hydrologic Flow Paths at Panola Mountain Research Watershed, Georgia, U.S.A.

    NASA Astrophysics Data System (ADS)

    Aulenbach, B. T.; Saraceno, J.; Shanley, J. B.

    2014-12-01

    Dissolved organic carbon (DOC) has been a useful tracer of hydrologic flow paths that generate streamflow during hydrologic events. This is due to the distinct strong source of DOC in shallow soil horizons and specific landscape positions within a watershed. The variability in stream DOC concentration was examined in 76 hydrologic events between 1985 and 2014 at Panola Mountain Research Watershed, a small 41-hectare forested watershed near Atlanta, Georgia, U.S.A. Stream DOC concentrations ranged from about 1 to 2 mg/l (as C) in base flow and increased with discharge to a maximum of about 11 mg/l. DOC concentrations in shallow soil water at 15 cm depth varied between about 5 and 25 mg/l and were highest in the summer. Maximum stream event DOC concentrations were lower during winter and spring when conditions are wetter. The timing of the maximum event DOC concentration compared to the stormflow peak was variable. Summer events displayed an almost exclusive counterclockwise (ccw) hysteresis (DOC maximum occurring after the streamflow peak). During other seasons, events exhibited both clockwise (cw) and ccw hysteresis, no hysteresis, and occasionally a figure-8 shaped concentration-discharge response. The hysteretic patterns were compared to various attributes such as precipitation amount and intensity, base flow, streamflow response, and soil moisture antecedent conditions and event response at various soil depths. The ccw response was most related to shallow soil moisture response at a depth of 15 cm that either peaked at or after the hydrograph peak indicating higher contributions of DOC from shallow soils during the storm recession. A cw response was related to a rapid increase in soil moisture that plateaued well before the peak event discharge and occurred when the soil profile was wet. Other DOC response patterns occurred during either intermediate wetness conditions or more varied hydrologic dynamics. Spectral ultraviolet absorption (SUVA), an index of the

  14. Assessing relationships between human land uses and the decline of native mussels, fish, and macroinvertebrates in the Clinch and Powell River watershed, USA.

    PubMed

    Diamond, Jerome M; Bressler, David W; Serveiss, Victor B

    2002-06-01

    The free-flowing Clinch and Powell watershed in Virginia, USA, harbors a high number of endemic mussel and fish species but they are declining or going extinct at an alarming rate. To prioritize resource management strategies with respect to these fauna, a geographical information system was developed and various statistical approaches were used to relate human land uses with available fish, macroinvertebrate, and native mussel assemblage data. Both the Ephemeroptera, Plecoptera, Trichoptera (EPT) family-level index, and the fish index of biotic integrity (IBI) were lowest in a subwatershed with the greatest coal mining activity (analysis of variance [ANOVA], p < 0.05). Limited analyses in two other subwatersheds suggested that urban and agricultural land uses within a specified riparian corridor were more related to mussel species richness and fish IBI than land uses in entire catchments. Based on land uses within a riparian corridor of 200 m x 2 km for each biological site in the watershed, fish IBI was inversely related to percent cropland and urban area and positively related to pasture area (stepwise multiple regression, R2 = 0.55, p < 0.05). Sites less than 2 km downstream of urban areas, major highways, or coal mine activities had a significantly lower mean IBI value than those more than 2 km away (ANOVA, p < .05). Land use effects included poorer instream cover and higher substrate embeddedness (t test, p < 0.05). Weaker land use relationships were observed for EPT and mussel species richness. Episodic spills of toxic materials, originating from transportation corridors, mines, and industrial facilities, also have resulted in local extirpations of native species. particularly mussels. The number of co-occurring human activities was directly related to stream elevation in the Clinch River, with more human land uses in headwater areas. Approximately 60% of known U.S. Fish and Wildlife mussel concentration sites in the watershed are located within 2 km of at

  15. Anguillicola crassus infection in Anguilla rostrata from small tributaries of the Hudson River watershed, New York, USA.

    PubMed

    Machut, L S; Limburg, K E

    2008-03-03

    We studied the invasion of the exotic nematode parasite Anguillicola crassus in the American eel Anguilla rostrata using tributaries of the Hudson River estuary. Yellow-phase American eels were sampled from 6 tributaries, and their swim bladders were examined for nematode infection. Prevalence averaged 39% with an intensity of 2.4 nematodes per eel. Parasite distribution was not significant along a latitudinal gradient; on the other hand, physical barriers (dams and natural waterfalls) significantly reduced infections upstream. Urbanization may increase the susceptibility of eels to infection; we found significantly elevated infection rates when urbanized lands exceeded 15% of the tributary catchment area. Yellow-phase eel condition was not affected by parasite infection. The invasion of the entire Hudson River watershed is ongoing and therefore will continue to be a management concern. Further analysis of the parasite-host interaction in North America is warranted.

  16. Biomonitoring in the Boulder River watershed, Montana, USA: metal concentrations in biofilm and macroinvertebrates, and relations with macroinvertebrate assemblage

    USGS Publications Warehouse

    Rhea, D.T.; Harper, D.D.; Farag, A.M.; Brumbaugh, W.G.

    2006-01-01

    Portions of the Boulder River watershed contain elevated concentrations of arsenic, cadmium, copper, lead, and zinc in water, sediment, and biota. We measured concentrations of As, Cd, Cu, Pb, and Zn in biofilm and macroinvertebrates, and assessed macroinvertebrate assemblage and aquatic habitat with the objective of monitoring planned remediation efforts. Concentrations of metals were generally higher in downstream sites compared with upstream or reference sites, and two sites contained metal concentrations in macroinvertebrates greater than values reported to reduce health and survival of resident trout. Macroinvertebrate assemblage was correlated with metal concentrations in biofilm and macroinvertebrates. However, macroinvertebrate metrics were significantly correlated with a greater number of biofilm metals (8) than metals in invertebrates (4). Lead concentrations in biofilm appeared to have the most significant impact on macroinvertebrate assemblage. Metal concentrations in macroinvertebrates were directly proportional to concentrations in biofilm, indicating biofilm as a potential surrogate for monitoring metal impacts in aquatic systems. ?? Springer Science+Business Media, Inc. 2006.

  17. Phosphorus source-sink relationships of stream sediments in the Rathbun Lake watershed in southern Iowa, USA.

    PubMed

    Hongthanat, Najphak; Kovar, John L; Thompson, Michael L; Russell, James R; Isenhart, Thomas M

    2016-08-01

    The surface waters of Rathbun Lake watershed in southern Iowa are impacted by agricultural sources of sediments and nutrients, including phosphorus (P). Because stream sediments often play an important role in regulating P concentrations in stream water, we investigated sediment-water column P relationships in four creeks within the watershed and then evaluated the relationship between sediment properties and indicators of the risk of P loss. Based on Mehlich-3-extractable P (17 to 68 mg kg(-1)) and degree of P saturation (2 to 12 %), stream bank and bed sediments at the four sites were unlikely to serve as major sources of P. However, equilibrium P concentrations, which ranged from 0.02 to 0.12 mg L(-1), indicated that bed sediments could release P to the water column depending on dissolved P (DP) concentrations in the stream water and the time of year. The likelihood of P desorption from the sediments increased with increasing pH (r = 0.92, p < 0.01) and sand content (r = 0.78, p < 0.05), but decreased with clay content (r = -0.72, p < 0.05) and iron (Fe) (r = -0.93, p < 0.001) associated with organic matter. From these results, we speculate that changes in land use within the riparian areas may, at least initially, have little effect on P concentrations in the streams. Low concentrations of DP relative to total P (TP) in these streams, however, suggest that P loads to Rathbun Lake can be reduced if P inputs from eroded bank sediments are controlled.

  18. The importance of diverse data types to calibrate a watershed model of the Trout Lake Basin, Northern Wisconsin, USA

    USGS Publications Warehouse

    Hunt, R.J.; Feinstein, D.T.; Pint, C.D.; Anderson, M.P.

    2006-01-01

    As part of the USGS Water, Energy, and Biogeochemical Budgets project and the NSF Long-Term Ecological Research work, a parameter estimation code was used to calibrate a deterministic groundwater flow model of the Trout Lake Basin in northern Wisconsin. Observations included traditional calibration targets (head, lake stage, and baseflow observations) as well as unconventional targets such as groundwater flows to and from lakes, depth of a lake water plume, and time of travel. The unconventional data types were important for parameter estimation convergence and allowed the development of a more detailed parameterization capable of resolving model objectives with well-constrained parameter values. Independent estimates of groundwater inflow to lakes were most important for constraining lakebed leakance and the depth of the lake water plume was important for determining hydraulic conductivity and conceptual aquifer layering. The most important target overall, however, was a conventional regional baseflow target that led to correct distribution of flow between sub-basins and the regional system during model calibration. The use of an automated parameter estimation code: (1) facilitated the calibration process by providing a quantitative assessment of the model's ability to match disparate observed data types; and (2) allowed assessment of the influence of observed targets on the calibration process. The model calibration required the use of a 'universal' parameter estimation code in order to include all types of observations in the objective function. The methods described in this paper help address issues of watershed complexity and non-uniqueness common to deterministic watershed models. ?? 2005 Elsevier B.V. All rights reserved.

  19. Effects of sediment-bound zinc contamination on early life stages of the mummichog (Fundulus heteroclitus L.) in the Christina watershed, Delaware, U.S.A.

    PubMed

    Guy, Christopher Paul; Pinkney, Alfred Eli; Taylor, Malcolm Herbert

    2006-05-01

    During the last century, the Christina River, the major estuarine river system in New Castle County (DE, USA), has received loadings of organic and inorganic chemicals, primarily from manufacturing facilities. Among the most abundant chemicals is zinc, which has accumulated in sediments at concentrations as high as 5,440 mg/kg. We studied the possible effects of zinc on early life stages of the mummichog (Fundulus heteroclitus), a resident species in the river and watershed. We conducted three different types of exposures. The first was a 96-h median lethal concentration (LC50) test with larvae exposed to waterborne zinc. The second was a larval exposure with zinc-spiked sediments (obtained from the relatively uncontaminated Magothy River in Anne Arundel County, MD, USA). The third was an embryo-larval exposure with Christina River sediments having a gradient of zinc concentrations. The average 96-h LC50 with newly hatched yolk sac larvae was 970 lig/L. In the larval tests, the average 7- and 21-d LC50s were 1154 and 1012 mg/kg, respectively. In the embryo-larval test, no significant difference was found in survival at concentrations between 38.8 and 1098 mg/kg. However, significant reductions were observed in condition factor at concentrations of 582, 799, and 1098 mg/kg. We calculated an average no-observed-effects concentration of 579 mg/kg and an average lowest-observed-effects concentration of 849 mg/kg for larval survival. Based on these results, we suggest that zinc in the Christina River may be affecting early life stages of the mummichog.

  20. RELATIONS OF FISH AND SHELLFISH DISTRIBUTIONS TO HABITAT AND WATER QUALITY IN THE MOBILE BAY ESTUARY, USA

    EPA Science Inventory

    The Mobile Bay estuary provides rich habitat for many fish and shellfish, including those identified as economically and ecologically important. The National Estuary Program has focused on restoration of degraded estuarine habitat on which these species depend. To support this ...

  1. Molecular Approach to Microbiological Examination of Water Quality in the Grand Bay National Estuarine Research Reserve (NERR) in Mississippi, USA.

    PubMed

    Kishinhi, Stephen S; Tchounwou, Paul B; Farah, Ibrahim O

    2013-01-01

    Grand Bay National Estuarine Research Reserve (NERR) is an important ecosystem in the Mississippi Gulf Coast. It serves as important nursery areas for juveniles of many species of fish. The bay is also used for fishing, crabbing, oyster togging, boating as well as recreation. Like in other aquatic environments, this bay may be contaminated by microorganisms including pathogenic bacteria. The objective of this study was to evaluate the microbiological quality of water in the Grand Bay NERR and determine the levels and potential source(s) of human fecal pollution. To achieve this goal, water samples were collected aseptically every month in Bayou Heron, Bayou Cumbest, Point Aux Chenes Bay and Bangs Lake. Enterococci were concentrated from water samples by membrane filtration according to the methodology outlined in USEPA Method 1600. After incubation, DNA was extracted from bacteria colonies on the membrane filters by using QIAamp DNA extraction kit. Water samples were also tested for the presence of traditional indicator bacteria including: heterotrophic plate count, total coliforms, fecal coliforms, and Enterococcus bacteria. The marker esp gene was detected in one site of Bayou Cumbest, an area where human populations reside. Data from this study indicates higher concentrations of indicator bacteria compared to the recommended acceptable levels. Presence of esp marker and high numbers of indicator bacteria suggest a public health concern for shellfish and water contact activities. Hence, control strategies should be developed and implemented to prevent further contamination of the Grand bay NERR waters.

  2. Composition of precipitation, bulk deposition, and runoff at a granitic bedrock catchment in the Loch Vale watershed, Colorado, USA

    USGS Publications Warehouse

    Clow, David W.; Mast, M. Alisa

    1995-01-01

    The chemical composition of precipitation, bulk deposition, and runoff from a 30-m2 granitic bedrock catchment in the Loch Vale Watershed in Rocky Mountain National Park was monitored over a 6-week period in the summer of 1994 to determine the importance of dry deposition in the alpine zone. Concentrations of acid anions and base cations were 1.1 to 4 times higher in bulk deposition than in precipitation. Concentrations of the same solutes were 3 to 10 times higher in runoff from the bedrock catchment than in bulk deposition, and during individual runoff events, the concentrations of most ions were highest in the initial runoff. Evaporation from the rock surface accounted for only a 15% increase in solute concentrations indicating that most of the dissolved load in bedrock runoff is derived from the dissolution of dry deposition that accumulates on the bedrock between storm events. These results indicate that dry deposition may be an important source of solutes to this alpine ecosystem.

  3. Effects of highway construction on stream water quality and macroinvertebrate condition in a Mid-Atlantic Highlands watershed, USA

    USGS Publications Warehouse

    Chen, Y.; Viadero, R.C.; Wei, X.; Fortney, Ronald H.; Hedrick, Lara B.; Welsh, S.A.; Anderson, James T.; Lin, L.-S.

    2009-01-01

    Refining best management practices (BMPs) for future highway construction depends on a comprehensive understanding of environmental impacts from current construction methods. Based on a before-after-control impact (BACI) experimental design, long-term stream monitoring (1997-2006) was conducted at upstream (as control, n = 3) and downstream (as impact, n = 6) sites in the Lost River watershed of the Mid-Atlantic Highlands region, West Virginia. Monitoring data were analyzed to assess impacts of during and after highway construction on 15 water quality parameters and macroinvertebrate condition using the West Virginia stream condition index (WVSCI). Principal components analysis (PCA) identified regional primary water quality variances, and paired t tests and time series analysis detected seven highway construction-impacted water quality parameters which were mainly associated with the second principal component. In particular, impacts on turbidity, total suspended solids, and total iron during construction, impacts on chloride and sulfate during and after construction, and impacts on acidity and nitrate after construction were observed at the downstream sites. The construction had statistically significant impacts on macroinvertebrate index scores (i.e., WVSCI) after construction, but did not change the overall good biological condition. Implementing BMPs that address those construction-impacted water quality parameters can be an effective mitigation strategy for future highway construction in this highlands region. Copyright ?? 2009 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

  4. Effects of highway construction on stream water quality and macroinvertebrate condition in a mid-Atlantic highlands watershed, USA

    USGS Publications Warehouse

    Welsh, Stuart A.; Chen, Yushun; Viadero, Stuart C.; Wei, Xinchao; Hedrick, Lara B.; Anderson, James T.; Lin, Lian-Shin

    2009-01-01

    Refining best management practices (BMPs) for future highway construction depends on a comprehensive understanding of environmental impacts from current construction methods. Based on a before-after-control impact (BACI) experimental design, long-term stream monitoring (1997–2006) was conducted at upstream (as control, n = 3) and downstream (as impact, n = 6) sites in the Lost River watershed of the Mid-Atlantic Highlands region, West Virginia. Monitoring data were analyzed to assess impacts of during and after highway construction on 15 water quality parameters and macroinvertebrate condition using the West Virginia stream condition index (WVSCI). Principal components analysis (PCA) identified regional primary water quality variances, and paired t tests and time series analysis detected seven highway construction-impacted water quality parameters which were mainly associated with the second principal component. In particular, impacts on turbidity, total suspended solids, and total iron during construction, impacts on chloride and sulfate during and after construction, and impacts on acidity and nitrate after construction were observed at the downstream sites. The construction had statistically significant impacts on macroinvertebrate index scores (i.e., WVSCI) after construction, but did not change the overall good biological condition. Implementing BMPs that address those construction-impacted water quality parameters can be an effective mitigation strategy for future highway construction in this highlands region.

  5. Effects of highway construction on stream water quality and macroinvertebrate condition in a mid-atlantic highlands watershed, USA.

    PubMed

    Chen, Yushun; Viadero, Roger C; Wei, Xinchao; Fortney, Ronald; Hedrick, Lara B; Welsh, Stuart A; Anderson, James T; Lin, Lian-Shin

    2009-01-01

    Refining best management practices (BMPs) for future highway construction depends on a comprehensive understanding of environmental impacts from current construction methods. Based on a before-after-control impact (BACI) experimental design, long-term stream monitoring (1997-2006) was conducted at upstream (as control, n = 3) and downstream (as impact, n = 6) sites in the Lost River watershed of the Mid-Atlantic Highlands region, West Virginia. Monitoring data were analyzed to assess impacts of during and after highway construction on 15 water quality parameters and macroinvertebrate condition using the West Virginia stream condition index (WVSCI). Principal components analysis (PCA) identified regional primary water quality variances, and paired t tests and time series analysis detected seven highway construction-impacted water quality parameters which were mainly associated with the second principal component. In particular, impacts on turbidity, total suspended solids, and total iron during construction, impacts on chloride and sulfate during and after construction, and impacts on acidity and nitrate after construction were observed at the downstream sites. The construction had statistically significant impacts on macroinvertebrate index scores (i.e., WVSCI) after construction, but did not change the overall good biological condition. Implementing BMPs that address those construction-impacted water quality parameters can be an effective mitigation strategy for future highway construction in this highlands region.

  6. Emerging coral diseases in Kāne'ohe Bay, O'ahu, Hawai'i (USA): two major disease outbreaks of acute Montipora white syndrome

    USGS Publications Warehouse

    Aeby, Greta S.; Callahan, Sean; Cox, Evelyn F.; Runyon, Christina M.; Smith, Ashley; Stanton, Frank G.; Ushijima, Blake; Work, Thierry M.

    2016-01-01

    In March 2010 and January 2012, we documented 2 widespread and severe coral disease outbreaks on reefs throughout Kāne‘ohe Bay, Hawai‘i (USA). The disease, acute Montipora white syndrome (aMWS), manifested as acute and progressive tissue loss on the common reef coral M. capitata. Rapid visual surveys in 2010 revealed 338 aMWS-affected M. capitata colonies with a disease abundance of (mean ± SE) 0.02 ± 0.01 affected colonies per m of reef surveyed. In 2012, disease abundance was significantly higher (1232 aMWS-affected colonies) with 0.06 ± 0.02 affected colonies m-1. Prior surveys found few acute tissue loss lesions in M. capitata in Kāne‘ohe Bay; thus, the high number of infected colonies found during these outbreaks would classify this as an emerging disease. Disease abundance was highest in the semi-enclosed region of south Kāne‘ohe Bay, which has a history of nutrient and sediment impacts from terrestrial runoff and stream discharge. In 2010, tagged colonies showed an average tissue loss of 24% after 1 mo, and 92% of the colonies continued to lose tissue in the subsequent month but at a slower rate (chronic tissue loss). The host-specific nature of this disease (affecting only M. capitata) and the apparent spread of lesions between M. capitatacolonies in the field suggest a potential transmissible agent. The synchronous appearance of affected colonies on multiple reefs across Kāne‘ohe Bay suggests a common underlying factor. Both outbreaks occurred during the colder, rainy winter months, and thus it is likely that some parameter(s) associated with winter environmental conditions are linked to the emergence of disease outbreaks on these reefs.

  7. Hydrogeologic controls on groundwater discharge and nitrogen loads in a coastal watershed

    USGS Publications Warehouse

    Russonielloa, Christopher J.; Konikow, Leonard F.; Kroeger, Kevin D.; Fernandez, Cristina; Andres, A. Scott; Michael, Holly A.

    2016-01-01

    Submarine groundwater discharge (SGD) is a small portion of the global water budget, but a potentially large contributor to coastal nutrient budgets due to high concentrations relative to stream discharge. A numerical groundwater flow model of the Inland Bays Watershed, Delaware, USA, was developed to identify the primary hydrogeologic factors that affect groundwater discharge rates and transit times to streams and bays. The distribution of groundwater discharge between streams and bays is sensitive to the depth of the water table below land surface. Higher recharge and reduced hydraulic conductivity raised the water table and increased discharge to streams relative to bays compared to the Reference case (in which 66% of recharge is discharged to streams). Increases to either factor decreased transit times for discharge to both streams and bays compared to the Reference case (in which mean transit times are 56.5 and 94.3 years, respectively), though sensitivity to recharge is greater. Groundwater-borne nitrogen loads were calculated from nitrogen concentrations measured in discharging fresh groundwater and modeled SGD rates. These loads combined with long SGD transit times suggest groundwater-borne nitrogen reductions and estuarine water quality improvements will lag decades behind implementation of efforts to manage nutrient sources. This work enhances understanding of the hydrogeologic controls on and uncertainties in absolute and relative rates and transit times of groundwater discharge to streams and bays in coastal watersheds.

  8. Hydrogeologic controls on groundwater discharge and nitrogen loads in a coastal watershed

    USGS Publications Warehouse

    Russoniello, Chrtopher J.; Konikow, Leonard F.; Kroeger, Kevin D.; Fernandez, Cristina; Andres, A. Scott; Michael, Holly A.

    2016-01-01

    Submarine groundwater discharge (SGD) is a small portion of the global water budget, but a potentially large contributor to coastal nutrient budgets due to high concentrations relative to stream discharge. A numerical groundwater flow model of the Inland Bays Watershed, Delaware, USA, was developed to identify the primary hydrogeologic factors that affect groundwater discharge rates and transit times to streams and bays. The distribution of groundwater discharge between streams and bays is sensitive to the depth of the water table below land surface. Higher recharge and reduced hydraulic conductivity raised the water table and increased discharge to streams relative to bays compared to the Reference case (in which 66% of recharge is discharged to streams). Increases to either factor decreased transit times for discharge to both streams and bays compared to the Reference case (in which mean transit times are 56.5 and 94.3 years, respectively), though sensitivity to recharge is greater. Groundwater-borne nitrogen loads were calculated from nitrogen concentrations measured in discharging fresh groundwater and modeled SGD rates. These loads combined with long SGD transit times suggest groundwater-borne nitrogen reductions and estuarine water quality improvements will lag decades behind implementation of efforts to manage nutrient sources. This work enhances understanding of the hydrogeologic controls on and uncertainties in absolute and relative rates and transit times of groundwater discharge to streams and bays in coastal watersheds.

  9. Petrographic observations on the Exmore breccia, ICDP-USGS drilling at Eyreville, Chesapeake Bay impact structure, USA

    USGS Publications Warehouse

    Reimold, W.U.; Bartosova, K.; Schmitt, R.T.; Hansen, B.; Crasselt, C.; Koeberl, C.; Wittmann, A.; Powars, D.S.

    2009-01-01

    The International Continental Scientific Drilling Program (ICDP)-U.S. Geological Survey (USGS) Eyreville A and B drill cores sampled crater fill in the region of the crater moat, ??9 km to the NE of the center of the Chesapeake Bay impact structure, Virginia, USA. They provide a 953 m section (444-1397 m depth) of sedimentary clast breccia and intercalated sedimentary and crystalline megablocks knownas Exmore beds, deposited on top of the impactite sequence between 1397 and 1551 m depth. We petrographically investigated the sandy-clayey groundmass-dominated breccia, which resembles a diamictite ("Exmore breccia"), and which, in its lower parts, carries sedimentary and crystalline blocks. The entire breccia interval is characterizedby the presence of glauconite and bioclastic carbonate, which distinguishes the Exmore breccia from other sandy facies above and below in the stratigraphy. The sediment-clast breccia exhibits strong heterogeneity from sample to sample with respect to groundmass nature, e.g., clay versus sand content, as well as clast content, in general, and shocked clast content, in particular. There is a consistently signifi cantly larger macroscopic sedimentary to crystalline clast content. On the microscopic scale, the intersample sediment to crystalline clast ratios are quite variable. A very small component of shocked material, in the form of shock-deformed quartz, and to an even lesser degree feldspar, and somewhat more abundant but still relatively scarce shardshaped,altered melt particles, is present throughout the section. However, between ??458 and 469 m, and between 514 and 527 m depths, the abundance of such melt particlesis notably enhanced. These sections are also chemically distinct and relatively more mafic than the other parts of the Exmore breccia. It appears that from the time of deposition of the 527 m material, calming of the ocean occurred over the crater area as a result of abatement of resurge activity, so that ejecta from the

  10. CASCO BAY PLAN

    EPA Science Inventory

    Casco Bay lies at the heart of Maine's most populated area. The health of its waters, wetlands, and wildlife depend in large part on the activities of the quarter-million residents who live in its watershed. Less than 30 years ago, portions of Casco Bay were off-limits to recr...

  11. Real World: NASA and the Chesapeake Bay

    NASA Video Gallery

    Learn how NASA uses Earth observing satellites to monitor conditions in the Chesapeake Bay over time. Information about pollution, eutrophication, land cover and watershed runoff helps water manage...

  12. A ten year summary of concurrent ambient water column and sediment toxicity tests in the Chesapeake Bay watershed: 1990-1999.

    PubMed

    Hall, Lenwood W; Anderson, Ronald D; Alden, Raymond W

    2002-06-01

    The goal of this study was to identify the relative toxicity of ambient areas in the Chesapeake Bay watershed by using a suite of concurrent water column and sediment toxicity tests at seventy-five ambient stations in 20 Chesapeake Bay rivers from 1990 through 1999. Spatial and temporal variability was examined at selected locations throughout the 10 yr study. Inorganic and organic contaminants were evaluated in ambient water and sediment concurrently with water column and sediment tests to assess possible causes of toxicity although absolute causality can not be established. Multivariate statistical analysis was used to develop a multiple endpoint toxicity index (TOX-INDEX) at each station for both water column and sediment toxicity data. Water column tests from the 10 yr testing period showed that 49% of the time, some degree of toxicity was reported. The most toxic sites based on water column results were located in urbanized areas such as the Anacostia River, Elizabeth River and the Middle River. Water quality criteria for copper, lead, mercury, nickel and zinc were exceeded at one or more of these sites. Water column toxicity was also reported in localized areas of the South and Chester Rivers. Both spatial and temporal variability was reported from the suite of water column toxicity tests. Some degree of sediment toxicity was reported from 62% of the tests conducted during the ten year period. The Elizabeth River and Baltimore Harbor stations were reported as the most toxic areas based on sediment results. Sediment toxicity guidelines were exceeded for one or more of the following metals at these two locations: arsenic, cadmium, chromium, copper, lead, nickel and zinc. At the Elizabeth River stations nine of sixteen semi-volatile organics and two of seven pesticides measured exceeded the ER-M values in 1990. Ambient sediment toxicity tests in the Elizabeth River in 1996 showed reduced toxicity. Various semi-volatile organics exceeded the ER-M values at a

  13. Sources of dissolved and particulate organic material in Loch Vale Watershed, Rocky Mountain National Park, Colorado, USA

    USGS Publications Warehouse

    Baron, J.; McKnight, D.; Denning, A.S.

    1991-01-01

    The sources of both dissolved organic carbon (DOC) and particulate organic carbon (POC) to an alpine (Sky Pond) and a subalpine lake (The Loch) in Rocky Mountain National Park were explored for four years. The importance of both autochthonous and allochthonous sources of organic matter differ, not only between alpine and subalpine locations, but also seasonally. Overall, autochthonous sources dominate the organic carbon of the alpine lake, while allochthonous sources are a more significant source of organic carbon to the subalpine lake. In the alpine lake, Sky Pond, POC makes up greater than one third of the total organic matter content of the water column, and is related to phytoplankton abundance. Dissolved organic carbon is a product of within-lake activity in Sky Pond except during spring snowmelt and early summer (May-July), when stable carbon isotope ratios suggest a terrestrial source. In the subalpine lake, The Loch, DOC is a much more important constituent of water column organic material than POC, comprising greater than 90% of the spring snowmelt organic matter, and greater than 75% of the organic matter over the rest of the year. Stable carbon isotope ratios and a very strong relation of DOC with soluble Al(tot) indicate DOC concentrations are almost entirely related to flushing of soil water from the surrounding watershed during spring snowmelt. Stable carbon isotope ratios indicate that, for both lakes, phytoplankton is an important source of DOC in the winter, while terrestrial material of plant or microbial origin contributes DOC during snowmelt and summer. ?? 1991 Kluwer Academic Publishers.

  14. Isotope variations of dissolved Zn in the Rio Grande watershed, USA: The role of adsorption on Zn isotope composition

    NASA Astrophysics Data System (ADS)

    Szynkiewicz, Anna; Borrok, David M.

    2016-01-01

    In order to better understand the factors influencing zinc (Zn) isotope composition in hydrological systems, we analyzed the δ66Zn of dissolved Zn in the streams and groundwater of the Upper and Middle Rio Grande watershed in Colorado and New Mexico, United States. The stream water samples have a wider variation of δ66Zn (-0.57 to + 0.41 ‰ relative to the JMC 3-0749-Lyon standard) than groundwater samples (-0.13 to + 0.12 ‰) and than samples from streams that are in close proximity to abandoned mining sites (+0.24 to + 0.40 ‰). Regional changes of bedrock geology, from primarily igneous rocks to primarily sedimentary rocks, have no resolvable effect on the δ66Zn of aqueous samples. Instead, an increase in water pH from 7.5 to 8.5 corresponds to a considerable decrease in the δ66Zn of dissolved Zn (R2 = - 0.37, p = 0.003, n = 22). Consequently, we link the observed Zn isotope variations to the process of adsorption of Zn onto suspended sediment and bedrock minerals (average Δ66Znadsorbed-dissolved = + 0.31 ‰). Our results are in good agreement with previous experimental and empirical studies suggesting that Zn adsorption leads to a residual dissolved pool enriched in light Zn isotopes. Given that anthropogenic Zn sources can also be responsible for lowering of δ66Zn, and may overlap with the pH/adsorption effect on δ66Zn, the latter needs to be carefully considered in future studies to differentiate between natural and anthropogenic factors influencing Zn isotopes in this and other aquatic systems.

  15. Remarkable invasion of San Francisco Bay (California, USA), by the Asian clam Potamocorbula amurensis. I. Introduction and dispersal

    USGS Publications Warehouse

    Carlton, James T.; Thompson, Janet K.; Schemel, Laurence E.; Nichols, Frederic H.

    1990-01-01

    The euryhaline bivalve mollusc Potamocorbula amurensis (family Corbulidae), a native of China, Japan, and Korea, has recently appeared and become very abundant in San Francisco Bay. This clam appears to have been introduced as veliger larvae in the seawater ballast of cargo vessels. It was first collected in northern San Francisco Bay in late 1986. P, amurensis then spread throughout the estuary within 2 yr and reached densities at some sites exceeding 10 000 m-2 It lives primarily in the subtidal on all substrates (mud, sand, peat, and clay) and is found in the full range of bay salinities (< 1 to 33%). Its explosive increase in abundance and spread may result in major alterations of the San Francisco Bay estuary ecosystem. These could include changes in (1) trophic dynamics (through competition with other suspension-feeding and deposit-feeding infauna; changes in benthic community energy flow; availability of a new and abundant prey item for birds, fish, and crabs; and reduction - as a result of its filter feeding - of phytoplankton standmg stock) and (2) benthic dynamics (through inhibition and/or enhancement of infauna due to substrate destabilization; alteration of suspended sediment load of near-bottom water; and change of sediment surface redox balance). The early detection of the appearance and spread of P. amurensis in San Francisco Bay makes this one of the best documented invasions of any estuary in the world.

  16. Ground-water discharge and base-flow nitrate loads of nontidal streams, and their relation to a hydrogeomorphic classification of the Chesapeake Bay Watershed, middle Atlantic Coast

    USGS Publications Warehouse

    Bachman, L. Joseph; Lindsey, Bruce D.; Brakebill, John W.; Powars, David S.

    1998-01-01

    Existing data on base-flow and groundwater nitrate loads were compiled and analyzed to assess the significance of groundwater discharge as a source of the nitrate load to nontidal streams of the Chesapeake Bay watershed. These estimates were then related to hydrogeomorphic settings based on lithology and physiographic province to provide insight on the areal distribution of ground-water discharge. Base-flow nitrate load accounted for 26 to about 100 percent of total-flow nitrate load, with a median value of 56 percent, and it accounted for 17 to 80 percent of total-flow total-nitrogen load, with a median value of 48 percent. Hydrograph separations were conducted on continuous streamflow records from 276 gaging stations within the watershed. The values for base flow thus calculated were considered an estimate of ground-water discharge. The ratio of base flow to total flow provided an estimate of the relative importance of ground-water discharge within a basin. Base-flow nitrate loads, total-flow nitrate loads, and total-flow total-nitrogen loads were previously computed from water-quality and discharge measurements by use of a regression model. Base-flow nitrate loads were available from 78 stations, total-flow nitrate loads were available from 86 stations, and total-flow total-nitrogen loads were available for 48 stations. The percentage of base-flow nitrate load to total-flow nitrate load could be computed for 57 stations, whereas the percentage of base-flow nitrate load to totalflow total-nitrogen load could be computed for 36 stations. These loads were divided by the basin area to obtain yields, which were used to compare the nitrate discharge from basins of different sizes. The results indicate that ground-water discharge is a significant source of water and nitrate to the total streamflow and nitrate load. Base flow accounted for 16 to 92 percent of total streamflow at the 276 sampling sites, with a median value of 54 percent. It is estimated that of the 50

  17. Population ecology and shell chemistry of a phytal ostracode species (Loxoconcha matagordensis) in the Chesapeake Bay watershed

    USGS Publications Warehouse

    Vann, C.D.; Cronin, T. M.; Dwyer, G.S.

    2004-01-01

    Population ecology and shell chemistry were studied in the phytal ostracode Loxoconcha matagordensis (Swain 1955) collected from Zostera marina seagrass beds in the Chesapeake Bay to provide seasonal constraints on shell secretion time for paleothermometry. Population density and age structure were defined by two main breeding cycles that occurred between 01 to 15 June and 02 to 16 August 2001. The time interval between breeding cycles was ???2 months and total juvenile standing crop increased almost three-fold between the first and second breeding cycles. Dark brown over-wintered adults comprised the majority of the population between March and April 2001, while newly secreted translucent adults were predominant between June and September. Seasonal shell Mg/Ca and Sr/Ca ratios were positively correlated with water temperature at both sites, with the strongest correlations occurring between June and September from newly secreted shells at Dameron Marsh. Old, dark brown shells contained 10% to 23% and 1% to 6% less Mg/Ca and Sr/Ca, respectively, than new shells. Because a fossil assemblage of L. matagordensis will contain ???30% old shells (dark-brown), these results suggest that fossil Mg/Ca ratios yield an integrated late spring to summer temperature signal. Shell Mg/Ca and Sr/Ca ratios of specimens of L. matagordensis collected from living Zostera were positively correlated, suggesting that temperature may influence both elemental ratios. Mg/Ca and Sr/Ca ratios of fossil shells of the related species Loxoconcha sp. A obtained from four sediment cores were also studied and exhibited a weaker correlation between the two elemental ratios. ?? 2004 Elsevier B.V. All rights reserved.

  18. Responses of Wetland Biota to Water Quality in Farmington Bay, Great Salt Lake, Utah, U.S.A.

    NASA Astrophysics Data System (ADS)

    Madon, S.; Hoven, H.; Miller, T.; Myers, L.

    2006-12-01

    The Farmington Bay wetlands are part of the Great Salt Lake ecosystem and are valued as important feeding and nesting areas for migratory birds and for support of aquatic life and various recreational activities. The construction of a causeway in 1969 subsequently reduced natural mixing between Farmington Bay and the Great Salt Lake, often causing nutrients to remain concentrated in Farmington Bay. In recent years, there has also been growing concern among natural resource agencies and local stakeholders about the effects of nutrient loads from publicly-owned treatment works (POTWs) and other natural and anthropogenic sources on the assimilative capacity of the Farmington Bay wetlands. In response to these concerns, the Utah Division of Water Quality began a program in 2004 to characterize the wetland ecosystems of Farmington Bay. The results presented in this study mainly represent the first year of a three-year characterization effort. Wetland sites representing a variety of wetland types along Farmington Bay were sampled in the fall of 2004 and included 16 sites receiving sheet-flow hydrology and 13 impounded sites. Sites included areas receiving flows from POTWs and reference sites which lacked such flows. Sampling was conducted at each site along established transects to characterize water quality (pH, total dissolved solids or TDS, dissolved oxygen, total P, total-N, and water temperature), wetland soils (pH, conductivity and organic matter), wetland plants (species, percent cover and plant height) and macroinvertebrates (species and numbers). Univariate and multivariate statistical tests were used to explore relationships between physical, chemical and biological variables and define key metrics of wetland function in relation to water quality. This study provides a preliminary evaluation of the ecological relationships and patterns between key biological and water quality parameters and offers useful insights into potential metrics that may be useful in

  19. Water Quality Assessment of the Los Angeles River Watershed, California, USA in Wet and Dry Weather Periods

    NASA Astrophysics Data System (ADS)

    Rezaie Boroon, M. H.; Von L Coo, C.

    2015-12-01

    The purpose of this study is to identify sources of potential pollutants and characterize urban water quality along the Los Angeles River from its head to the mouth during dry and wet weather periods. Los Angeles (LA) River flows through heavily populated urbanized area in the Los Angeles downtown. The LA River is an effluent-dominated water body during the dry season. The three waste water treatment plants (WWTP) including the Tillman, Burbank, and Glendale discharge the majority of the volume flowing in the LA River during the dry and wet period. The concentration values (ppm) for anions in the dry season ranging 5.5-16,027 (Cl), 0-1.0 (F), 0-21(NO3), 0-1.6 (PO4), and 13.3-2,312 (SO4); whereas the values (ppm) for anions in the wet season ranging 3.4-5,860 (Cl), 0-0.66 (F), 0-17 (NO3), 0-0.67 (PO4), 7.9- 745 (SO4). Dry season concentrations values for trace metals were obtained with values (ppb) ranging 0.9-10 (Ni), 0.8-62 (Zn), 1-4 (As), 0-1 (Pb) and 0-3 (Se). As for wet season trace metals (ppb) ranging 0.001-0.008 (Ni), 0.000001-0.038 (Zn), 0.0016-0.016 (As), 0.00099-0.0058 (Pb), 0.000001-0.0093 (Se). Higher concentrations values during the dry period in the LA River watershed may be attributed to the three WWTPs discharge (75% of the volume of water flowing in the LA River). In water-limited areas such as the Los Angeles basin, urban runoff is a water resource that could enhance restricted water supplies and to enhance localized renewable groundwater resources, thus an assessment of this precious water resource is important for local city and regulatory organizations. In water-limited areas such as the LA basin, urban runoff is a water resource that could enhance restricted water supplies and groundwater resources, thus an assessment of this precious water resource is important for local regulatory organizations.

  20. Seasonal concentrations of organic contaminants at the fall line of the Susquehanna River basin and estimated fluxes to northern Chesapeake Bay, USA

    SciTech Connect

    Foster, G.D.; Lippa, K.A.; Miller, C.V.

    2000-04-01

    Riverine fluxes of several pesticides and other organic contaminants from above the fall line of the Susquehanna River basin to northern Chesapeake Bay, USA, were quantified in 1994. Base flow and storm flow samples collected at the fall line of the river from February to December 1994 were analyzed for both dissolved and particulate phase contaminants. Measured concentrations of the organonitrogen and organophosphorus pesticides varied mainly in response to the timing of their application to agricultural fields. Conversely, the concentrations of the more particle-sorptive contaminants such as polychlorinated biphenyls (PCBs), organochlorine (OC) insecticides, and polycyclic aromatic hydrocarbons (PAHs) were more directly correlated with river flow throughout the year. Annual fluxes were almost entirely in the dissolved phase for the organonitrogen and organophosphorus pesticides, distributed between the dissolved and particulate phases for the PCBs and OC insecticides, and primarily in the particulate phase for the PAHs.

  1. Seasonal concentrations of organic contaminants at the fall line of the Susquehanna River basin and estimated fluxes to northern Chesapeake Bay, USA

    USGS Publications Warehouse

    Foster, G.D.; Lippa, K.A.; Miller, C.V.

    2000-01-01

    Riverine fluxes of several pesticides and other organic contaminants from above the fall line of the Susquehanna River basin to northern Chesapeake Bay, USA, were quantified in 1994. Base flow and storm flow samples collected at the fall line of the river from February to December 1994 were analyzed for both dissolved and particulate phase contaminants. Measured concentrations of the organonitrogen and organophosphorus pesticides varied mainly in response to the timing of their application to agricultural fields. Conversely, the concentrations of the more particle-sorptive contaminants such as polychlorinated biphenyls (PCBs), organochlorine (OC) insecticides, and polycyclic aromatic hydrocarbons (PAHs) were more directly correlated with river flow throughout the year. Annual fluxes were almost entirely in the dissolved phase for the organonitrogen and organophosphorus pesticides, distributed between the dissolved and particulate phases for the PCBs and OC insecticides, and primarily in the particulate phase for the PAHs.

  2. Influence of anthropogenic alterations on geomorphic response to climate variations and change in San Francisco Bay-Delta and watershed

    USGS Publications Warehouse

    Florsheim, J.L.; Dettinger, M.D.

    2004-01-01

    Global warming and attendant sea-level rise may soon impact geomorphic processes in the Sacramento-San Joaquin River and San Francisco Bay Delta systems. During the past two centuries, dramatic anthropogenic changes in sediment supply and pervasive structural controls on rivers and floodplains have altered geomorphic responses to floods throughout a zone that extends upstream from tidally influenced areas to dams that regulate flow. Current geomorphic responses to floods differ from natural responses due to historical actions that concentrated the pre-disturbance multiple-channel and flood-basin system into single channels isolated by levees from increasingly developed floodplains and flood bypass channels, altered flow and sediment regimes, and caused subsidence of leveed Delta Islands. A review of historic and current geomorphic responses to floods illustrates the dominance of structural controls on geomorphic changes in the lowland part of the Sacramento-San Joaquin system. Current climate-change projections for CA suggest that the total volume of snowmelt runoff that may be shifted from spring and added to winter flows is roughly 5 maf/yr, similar to the volume currently available for flood storage in Sierra Nevadan reservoirs. Changes in timing of reservoir releases to accommodate these changes could add to either the magnitude or duration of winter flood peaks, each causing different geomorphic responses. Increased wintertime flows that accompany already large floods could increase overbank flood extent, erosion, and sedimentation, or alternatively increase the depth and strength of confined flows and increase the risk of levee failures. Runoff released from reservoirs as a relatively constant addition to winter baseflow would increase the duration of bankfull or possibly "levee-full" flows. This scenario could lead to bank and levee failure through increased saturation and seepage erosion. Projected sea level rise of 1-2 m would compound vulnerability of

  3. Top-down control of phytoplankton by oysters in Chesapeake Bay, USA: Comment on Pomeroy et al. (2006)

    EPA Science Inventory

    Pomeroy et al. (2006) proposed that temporal and spatial mismatches between eastern oyster filtration and phytoplankton abundance will preclude restored stocks of eastern oysters from reducing the severity of hypoxia in the deep channel of central Chesapeake Bay. We refute this c...

  4. Integrated Geologic, Hydrologic, and Geophysical Investigations of the Chesapeake Bay Impact Structure, Virginia, USA: A Multi-Agency Program

    NASA Technical Reports Server (NTRS)

    Gohn, G. S.; Bruce, T. S.; Catchings, R. D.; Emry, S. R.; Johnson, G. H.; Levine, J. S.; McFarland, E. R.; Poag, C. W.; Powars, D. S.

    2001-01-01

    The Chesapeake Bay impact structure is the focus of an ongoing federal-state-local research program. Recent core drilling and geophysical surveys address the formative processes and hydrogeologic properties of this major "wet-target" impact. Additional information is contained in the original extended abstract.

  5. Foraminiferal assemblages in Biscayne Bay, Florida, USA: responses to urban and agricultural influence in a subtropical estuary.

    PubMed

    Carnahan, E A; Hoare, A M; Hallock, P; Lidz, B H; Reich, C D

    2009-01-01

    This study assessed foraminiferal assemblages in Biscayne Bay, Florida, a heavily utilized estuary, interpreting changes over the past 65 years and providing a baseline for future comparisons. Analyses of foraminiferal data at the genus level revealed three distinct biotopes. The assemblage from the northern bay was characterized by stress-tolerant taxa, especially Ammonia, present in low abundances ( approximately 2.0 x 10(3) foraminifers/gram) though relatively high diversity ( approximately 19 genera/sample). The southwestern margin of the bay was dominated by Ammonia and Quinqueloculina, an assemblage characterized by the lowest diversities ( approximately 12 genera/sample) and highest abundances ( approximately 1.1 x 10(4) foraminifers/gram), influenced by both reduced salinity and elevated organic-carbon concentrations. A diverse assemblage of smaller miliolids and rotaliids ( approximately 26 genera/sample) characterized the open-bay assemblage, which also had a significant component ( approximately 10%) of taxa that host algal endosymbionts. In the past 65 years, populations of symbiont-bearing taxa, which are indicators of normal-marine conditions, have decreased while stress-tolerant taxa, especially Ammonia spp., have increased in predominance.

  6. Effects of Irradiance on Benthic and Water Column Processes in a Gulf of Mexico Estuary: Pensacola Bay, Florida, USA

    EPA Science Inventory

    We examined the effect of light on water column and benthic fluxes in the Pensacola Bay estuary, a river-dominated system in the northeastern Gulf of Mexico. Measurements were made during summer 2003 and 2004 on 16 dates at along depth and salinity gradients. Dissolved oxygen flu...

  7. Foraminiferal assemblages in Biscayne Bay, Florida, USA: Responses to urban and agricultural influence in a subtropical estuary

    USGS Publications Warehouse

    Carnahan, E.A.; Hoare, A.M.; Hallock, P.; Lidz, B.H.; Reich, C.D.

    2009-01-01

    This study assessed foraminiferal assemblages in Biscayne Bay, Florida, a heavily utilized estuary, interpreting changes over the past 65 years and providing a baseline for future comparisons. Analyses of foraminiferal data at the genus level revealed three distinct biotopes. The assemblage from the northern bay was characterized by stress-tolerant taxa, especially Ammonia, present in low abundances (???2.0 ?? 103 foraminifers/gram) though relatively high diversity (???19 genera/sample). The southwestern margin of the bay was dominated by Ammonia and Quinqueloculina, an assemblage characterized by the lowest diversities (???12 genera/sample) and highest abundances (???1.1 ?? 104 foraminifers/gram), influenced by both reduced salinity and elevated organic-carbon concentrations. A diverse assemblage of smaller miliolids and rotaliids (???26 genera/sample) characterized the open-bay assemblage, which also had a significant component (???10%) of taxa that host algal endosymbionts. In the past 65 years, populations of symbiont-bearing taxa, which are indicators of normal-marine conditions, have decreased while stress-tolerant taxa, especially Ammonia spp., have increased in predominance. ?? 2009 Elsevier Ltd.

  8. Development and application of a comprehensive simulation model to evaluate impacts of watershed structures and irrigation water use on streamflow and groundwater: The case of Wet Walnut Creek Watershed, Kansas, USA

    USGS Publications Warehouse

    Ramireddygari, S.R.; Sophocleous, M.A.; Koelliker, J.K.; Perkins, S.P.; Govindaraju, R.S.

    2000-01-01

    This paper presents the results of a comprehensive modeling study of surface and groundwater systems, including stream-aquifer interactions, for the Wet Walnut Creek Watershed in west-central Kansas. The main objective of this study was to assess the impacts of watershed structures and irrigation water use on streamflow and groundwater levels, which in turn affect availability of water for the Cheyenne Bottoms Wildlife Refuge Management area. The surface-water flow model, POTYLDR, and the groundwater flow model, MODFLOW, were combined into an integrated, watershed-scale, continuous simulation model. Major revisions and enhancements were made to the POTYLDR and MODFLOW models for simulating the detailed hydrologic budget for the Wet Walnut Creek Watershed. The computer simulation model was calibrated and verified using historical streamflow records (at Albert and Nekoma gaging stations), reported irrigation water use, observed water-level elevations in watershed structure pools, and groundwater levels in the alluvial aquifer system. To assess the impact of watershed structures and irrigation water use on streamflow and groundwater levels, a number of hypothetical management scenarios were simulated under various operational criteria for watershed structures and different annual limits on water use for irrigation. A standard 'base case' was defined to allow comparative analysis of the results of different scenarios. The simulated streamflows showed that watershed structures decrease both streamflows and groundwater levels in the watershed. The amount of water used for irrigation has a substantial effect on the total simulated streamflow and groundwater levels, indicating that irrigation is a major budget item for managing water resources in the watershed. (C) 2000 Elsevier Science B.V.This paper presents the results of a comprehensive modeling study of surface and groundwater systems, including stream-aquifer interactions, for the Wet Walnut Creek Watershed in west

  9. Long-term trends in submersed aquatic vegetation (SAV) in Chesapeake Bay, USA, related to water quality

    USGS Publications Warehouse

    Orth, Robert J.; Williams, Michael R.; Marion, Scott R.; Wilcox, David J.; Carruthers, Tim J.B.; Moore, Kenneth A.; Kemp, W.M.; Dennison, William C.; Rybicki, Nancy B.; Peter Bergstrom,; Batiuk, Richard A.

    2010-01-01

    Chesapeake Bay supports a diverse assemblage of marine and freshwater species of submersed aquatic vegetation (SAV) whose broad distributions are generally constrained by salinity. An annual aerial SAV monitoring program and a bi-monthly to monthly water quality monitoring program have been conducted throughout Chesapeake Bay since 1984. We performed an analysis of SAV abundance and up to 22 environmental variables potentially influencing SAV growth and abundance (1984-2006). Historically, SAV abundance has changed dramatically in Chesapeake Bay, and since 1984, when SAV abundance was at historic low levels, SAV has exhibited complex changes including long-term (decadal) increases and decreases, as well as some large, single-year changes. Chesapeake Bay SAV was grouped into three broad-scale community-types based on salinity regime, each with their own distinct group of species, and detailed analyses were conducted on these three community-types as well as on seven distinct case-study areas spanning the three salinity regimes. Different trends in SAVabundance were evident in the different salinity regimes. SAV abundance has (a) continually increased in the low-salinity region; (b) increased initially in the medium-salinity region, followed by fluctuating abundances; and (c) increased initially in the high-salinity region, followed by a subsequent decline. In all areas, consistent negative correlations between measures of SAV abundance and nitrogen loads or concentrations suggest that meadows are responsive to changes in inputs of nitrogen. For smaller case-study areas, different trends in SAV abundance were also noted including correlations to water clarity in high-salinity case-study areas, but nitrogen was highly correlated in all areas. Current maximum SAV coverage for almost all areas remain below restoration targets, indicating that SAV abundance and associated ecosystem services are currently limited by continued poor water quality, and specifically high

  10. Evidence for thyroid endocrine disruption in wild fish in San Francisco Bay, California, USA. Relationships to contaminant exposures.

    PubMed

    Brar, Navdeep K; Waggoner, Claire; Reyes, Jesus A; Fairey, Russell; Kelley, Kevin M

    2010-02-18

    It is well documented that many coastal and estuarine environments adjacent to developed and industrialized urban centers, such as the San Francisco Bay Area, are significantly contaminated by anthropogenic chemicals. However, it is not well understood to what extent existing contaminants, many with continuing inflows into the environment, may impact exposed wildlife. This study provided an initial characterization of thyroid endocrine-related effects and their relationship to accumulated contaminants in two indigenous fish species sampled from different San Franicsco Bay Area study sites. Plasma concentrations of thyroxine (T4) were significantly reduced in fish sampled from highly impacted locations such as Oakland Inner Harbor and San Leandro Bay as compared with fish from other locations representing relatively lower human impact, including Bodega Bay, Redwood City and a remote site on Santa Catalina Island. Triiodothyronine (T3) levels also varied significantly by location, with differing T3/T4 ratios in fish from some locations suggestive of altered peripheral deiodinase activity. The changes in thyroid endocrine parameters were significantly correlated with hepatic concentrations of certain environmental contaminants. A large number of polychlorinated biphenyl (PCB) congeners, both co-planar (dioxin-like) and non-co-planar, exhibited significant inverse correlations with T4 levels in the fish, while in contrast, T3 and T3/T4 ratio were positively correlated with PCB exposures. The positive correlation between T3/T4 ratio and PCBs supports the hypothesis that environmental PCBs may alter T4 deiodination or turnover, actions of PCBs reported in laboratory experiments. Some relationships between chlorinated pesticides including DDT and chlordanes, but fewer relationships with PAHs, were also observed. Together, these findings indicate that the thyroid endocrine system is exhibiting alterations associated with different aquatic environments in the San Francisco

  11. Activated carbon amendment as a treatment for residual DDT in sediment from a superfund site in San Francisco Bay, Richmond, California, USA.

    PubMed

    Tomaszewski, Jeanne E; Werner, David; Luthy, Richard G

    2007-10-01

    Pesticide formulators formerly operating at Lauritzen Channel, a portion of San Francisco Bay near Richmond (CA, USA), caused contamination of sediment with dichlorodiphenyltrichloroethane (DDT). The present study evaluated the distribution of residual DDT in channel sediment six years following extensive remedial dredging. High DDT concentrations (up to 252 mg/ kg) were found in Young Bay Mud sampled across the channel. Particle analyses showed most of the contamination is contained in the clay/silt sediment fraction, and desorption tests showed that availability is greater for DDT metabolites than parent DDT. The present study examined the feasibility of using activated carbon amendment to sequester DDT from sediment, including an evaluation of reactivated carbon as a less costly alternative to virgin activated carbons. Treatment success of activated carbon amendment to sediment collected from Lauritzen Channel was measured by reductions in aqueous equilibrium concentrations and uptake in semipermeable membrane devices (SPMDs). Four different activated carbons were tested and, after one month of treatment with 3.2 weight % carbon, DDT aqueous equilibrium concentrations were reduced up to 83% and SPMD uptake was reduced up to 91%. Reactivated carbon was comparable with virgin carbons in all tests. Reduction in SPMD uptake of DDT by treatment with 3.2% reactivated carbon increased to 99% after 26 months of treatment. The effectiveness of activated carbon was dependent on the type, size, dose, and contact time. The results show the potential usefulness of activated carbon amendment as a follow-up remedial technology for management of residuals after dredging contaminated sediment.

  12. GRACILARIA VERMICULOPHYLLA (RHODOPHYTA, GRACILARIALES) IN THE VIRGINIA COASTAL BAYS, USA: COX1 ANALYSIS REVEALS HIGH GENETIC RICHNESS OF AN INTRODUCED MACROALGA.

    PubMed

    Gulbransen, Dana J; McGlathery, Karen J; Marklund, Maria; Norris, James N; Gurgel, Carlos Frederico D

    2012-10-01

    Gracilaria vermiculophylla (Ohmi) Papenfuss is an invasive alga that is native to Southeast Asia and has invaded many estuaries in North America and Europe. It is difficult to differentiate G. vermiculophylla from native forms using morphology and therefore molecular techniques are needed. In this study, we used three molecular markers (rbcL, cox2-cox3 spacer, cox1) to identify G. vermiculophylla at several locations in the western Atlantic. RbcL and cox2-cox3 spacer markers confirmed the presence of G. vermiculophylla on the east coast of the USA from Massachusetts to South Carolina. We used a 507 base pair region of cox1 mtDNA to (i) verify the widespread distribution of G. vermiculophylla in the Virginia (VA) coastal bays and (ii) determine the intraspecific diversity of these algae. Cox1 haplotype richness in the VA coastal bays was much higher than that previously found in other invaded locations, as well as some native locations. This difference is likely attributed to the more intensive sampling design used in this study, which was able to detect richness created by multiple, diverse introductions. On the basis of our results, we recommend that future studies take differences in sampling design into account when comparing haplotype richness and diversity between native and non-native studies in the literature.

  13. An evaluation of temporal changes in sediment accumulation and impacts on carbon burial in Mobile Bay, Alabama, USA

    USGS Publications Warehouse

    Smith, Christopher G.; Osterman, Lisa E.

    2014-01-01

    The estuarine environment can serve as either a source or sink of carbon relative to the coastal ocean carbon budget. A variety of time-dependent processes such as sedimentation, carbon supply, and productivity dictate how estuarine systems operate, and Mobile Bay is a system that has experienced both natural and anthropogenic perturbations that influenced depositional processes and carbon cycling. Sediments from eight box cores provide a record of change in bulk sediment accumulation and carbon burial over the past 110 years. Accumulation rates in the central part of the basin (0.09 g cm−2) were 60–80 % less than those observed at the head (0.361 g cm−2) and mouth (0.564 g cm−2) of the bay. Sediment accumulation in the central bay decreased during the past 90 years in response to both anthropogenic (causeway construction) and natural (tropical cyclones) perturbations. Sediment accumulation inevitably increased the residence time of organic carbon in the oxic zone, as observed in modeled remineralization rates, and reduced the overall carbon burial. Such observations highlight the critical balance among sediment accumulation, carbon remineralization, and carbon burial in dynamic coastal environments. Time-series analysis based solely on short-term observation would not capture the long-term effects of changes in sedimentation on carbon cycling. Identifying these relationships over longer timescales (multi-annual to decadal) will provide a far better evaluation of coastal ocean carbon budgets.

  14. Avian morbidity and mortality from botulism, aspergillosis, and salmonellosis at Jamaica Bay Wildlife Refuge, New York, USA

    USGS Publications Warehouse

    Brand, C.J.; Windingstad, R.M.; Siegfried, L.M.; Duncan, R.M.; Cook, R.M.

    1988-01-01

    During the summers of 1981 and 1982, studies were conducted at Jamaica Bay Wildlife Refuge, Long Island, New York, to determine whether annual water-level drawdowns used to create shorebird habitat also led to the occurrence of avian botulism (Clostridium botulinum type C). Low levels of morbidity and mortality from avian botulism occurred on the two ponds throughout both summers, but there was no apparent relationship between the occurrence or rates of botulism losses and drawdowns of the ponds. Botulism also occurred throughout both summers on other areas of the refuge. Botulinal toxin was found in fly larvae associated with avian carcasses, including birds that did not die from botulism. Toxin was not found in other samples of aquatic biota in the ponds, although it was demonstrated in a single sample of decomposing sea lettuce (Ulva lactuca) in Jamaica Bay. Aspergillosis (Aspergillus fumigatus) and salmonellosis (Salmonella spp.) were also frequently-diagnosed causes of morbidity and mortality. We believe that botulinal toxin present in carcasses of birds dying from botulism, or produced postmortem in birds dying from other causes, on the two ponds and other areas in Jamaica Bay were a major source of botulinal toxin. Toxin could be ingested by birds through direct scavenging on carcasses, or by consumption of toxic fly larvae associated with carcasses. Diligent carcass pickup at the two ponds is recommended to reduce mortality from avian botulism.

  15. Mercury burdens in Chinese mitten crabs (Eriocheir sinensis) in three tributaries of southern San Francisco Bay, California, USA

    USGS Publications Warehouse

    Hui, C.A.; Rudnick, D.; Williams, E.

    2005-01-01

    Chinese mitten crabs (Eriocheir sinensis), endemic to Asia, were first reported in the San Francisco Bay in 1992. They are now established in nearly all San Francisco Bay tributaries. These crabs accumulate more metals, such as mercury, than crustaceans living in the water column. Because their predators include fish, birds, mammals and humans, their mercury burdens have an exceptional potential to impact the ecosystem and public health. We sought to elucidate the potential threat of mitten crab mercury burdens in three adjacent streams in southern San Francisco Bay, one of which is known to be contaminated with mercury. Mitten crabs had hepatopancreas concentrations of total mercury and methylmercury that did not differ among streams. The maximum burden we measured was below the action level of 1 ppm recommended by the USEPA. Hepatopancreas concentrations of methylmercury declined with increasing crab size, suggesting a mechanism for mercury excretion and that predators might reduce mercury exposure if they select larger crabs. Because mercury may be heterogeneously distributed among tissues, estimation of the impacts of crab mercury burdens on the environment requires more data on the feeding preferences of predators. Hepatopancreas concentrations of mercury decline with crab size, which may have important consequences for bio-magnification in food webs. ?? 2004 Elsevier Ltd. All rights reserved.