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Savannah River Site (savannah + river_site)
Selected AbstractsRemarkable Amphibian Biomass and Abundance in an Isolated Wetland: Implications for Wetland ConservationCONSERVATION BIOLOGY, Issue 5 2006J. WHITFIELD GIBBONS biodiversidad; declinación de anfibios; recuperación de humedales sequía; uso de suelo Abstract:,Despite the continuing loss of wetland habitats and associated declines in amphibian populations, attempts to translate wetland losses into measurable losses to ecosystems have been lacking. We estimated the potential productivity from the amphibian community that would be compromised by the loss of a single isolated wetland that has been protected from most industrial, agricultural, and urban impacts for the past 54 years. We used a continuous drift fence at Ellenton Bay, a 10-ha freshwater wetland on the Savannah River Site, near Aiken, South Carolina (U.S.A.), to sample all amphibians for 1 year following a prolonged drought. Despite intensive agricultural use of the land surrounding Ellenton Bay prior to 1951, we documented 24 species and remarkably high numbers and biomass of juvenile amphibians (>360,000 individuals; >1,400 kg) produced during one breeding season. Anurans (17 species) were more abundant than salamanders (7 species), comprising 96.4% of individual captures. Most (95.9%) of the amphibian biomass came from 232095 individuals of a single species of anuran (southern leopard frog[Rana sphenocephala]). Our results revealed the resilience of an amphibian community to natural stressors and historical habitat alteration and the potential magnitude of biomass and energy transfer from isolated wetlands to surrounding terrestrial habitat. We attributed the postdrought success of amphibians to a combination of adult longevity (often >5 years), a reduction in predator abundance, and an abundance of larval food resources. Likewise, the increase of forest cover around Ellenton Bay from <20% in 1951 to >60% in 2001 probably contributed to the long-term persistence of amphibians at this site. Our findings provide an optimistic counterpoint to the issue of the global decline of biological diversity by demonstrating that conservation efforts can mitigate historical habitat degradation. Resumen:,A pesar de la pérdida de hábitats de humedales y las declinaciones asociadas de poblaciones de anfibios, se han realizado pocos intentos para traducir las pérdidas de humedales en pérdidas mensurables en los ecosistemas. Estimamos la productividad potencial de la comunidad de anfibios que se afectaría por la pérdida de un humedal aislado que ha estado protegido de los impactos industriales, agrícolas y urbanos durante los últimos 54 años. Utilizamos un cerco de desvío en la Bahía Ellentonn, un humedal dulceacuícola de 10 ha en el Río Savannah, cerca de Aiken, Carolina del Sur (E.U.A.), para muestrear todos los anfibios durante 1 año después de una sequía prolongada. A pesar del intensivo uso agrícola del suelo alrededor de la Bahía Ellenton antes de 1951, documentamos 24 especies y números y biomasa de anfibios juveniles notablemente altos (>360,000 individuos; >1,400 kg) en una temporada reproductiva. Los anuros (17 especies) fueron más abundantes que las salamandras (7 especies), y comprendieron 96.4% de las capturas individuales. La mayor parte (95.9%) de la biomasa provino de 232095 individuos de una sola especie de anuro (Rana sphenocephala). Nuestros resultados revelaron que la resiliencia de la comunidad de anfibios a los estresantes naturales y a la alteración histórica del hábitat y la magnitud potencial de la transferencia de biomasa y energía desde los humedales aislados hacia el hábitat terrestre circundante. Atribuimos el éxito post-sequía de los anfibios a una combinación de longevidad de adultos (a menudo > 5 años), la reducción de la abundancia de depredadores y la abundancia de recursos alimenticios para las larvas. Asimismo, el incremento de la cobertura forestal alrededor de la Bahía Ellerton de < 20% en 1951 a > 60% en 2001 probablemente contribuyó a la persistencia de los anfibios a largo plazo en este sitio. Nuestros hallazgos proporcionan un contrapunto optimista al tema de la declinación global de la diversidad biológica al demostrar que los esfuerzos de conservación pueden mitigar a la degradación histórica del hábitat. [source] Deterministic and Stochastic Modeling of Aquifer Stratigraphy, South CarolinaGROUND WATER, Issue 2 2000Russell B. Miller Deterministic and stochastic methods of three-dimensional hydrogeologic modeling are applied to characterization of contaminated Eocene aquifers at the Savannah River Site, South Carolina. The results address several important issues, including the use of multiple types of data in creating high-resolution aquifer models and the application of sequence-stratigraphic constraints. Specific procedures used include defining grid architecture stratigraphically, upscaling, modeling lithologic properties, and creating multiple equiprobable realizations of aquifer stratigraphy. An important question answered by the study is how to incorporate gamma-ray borehole-geophysical data in areas of anomalous log response, which occurs commonly in aquifers and confining units of the Atlantic Coastal Plain and other areas. To overcome this problem, gamma-ray models were conditioned to grain-size and lithofacies realizations. The investigation contributes to identifying potential pathways for downward migration of contaminants, which have been detected in confined aquifers at the modeling site. The approach followed in this investigation produces quantitative, stratigraphically constrained, geocellular models that incorporate multiple types of data from borehole-geophysical logs and continuous cores. The use of core-based stochastic realizations in conditioning deterministic models provides the advantage of incorporating lithologic information based on direct observations of cores rather than using only indirect measurements from geophysical logs. The high resolution of the models is demonstrated by the representation of thin, discontinuous clay beds that act as local barriers to flow. The models are effective in depicting the contrasts in geometry and heterogeneity between sheet-like nearshore-transgressive sands and laterally discontinuous sands of complex shoreline environments. [source] Seasonal diets of insectivorous birds using canopy gaps in a bottomland forestJOURNAL OF FIELD ORNITHOLOGY, Issue 1 2007Christopher E. Moorman ABSTRACT Little is known about how insectivorous bird diets are influenced by arthropod availability and about how these relationships vary seasonally. We captured birds in forest-canopy gaps and adjacent mature forest during 2001 and 2002 at the Savannah River Site in Barnwell County, South Carolina, and flushed their crops to gather information about arthropods eaten during four periods: spring migration, breeding, postbreeding, and fall migration. Arthropod availability for foliage- and ground-gleaning birds was examined by leaf clipping and pitfall trapping. Coleopterans and Hemipterans were used by foliage- and ground-gleaners more than expected during all periods, whereas arthropods in the orders Araneae and Hymenoptera were used as, or less than, expected based on availability during all periods. Ground-gleaning birds used Homopterans and Lepidopterans in proportions higher than availability during all periods. Arthropod use by birds was consistent from spring through fall migration, with no apparent seasonal shift in diet. Based on concurrent studies, heavily used orders of arthropods were equally abundant or slightly less abundant in canopy gaps than in the surrounding mature forest, but bird species were most frequently detected in gaps. Such results suggest that preferential feeding on arthropods by foliage-gleaning birds in gap habitats reduced arthropod densities or, alternatively, that bird use of gap and forest habitat was not determined by food resources. The abundance of arthropods across the stand may have allowed birds to remain in the densely vegetated gaps where thick cover provides protection from predators. SINOPSIS Se conoce poco de como la dieta de insectívoros está influenciada por la disponibilidad de artrópodos y de como estas interacciones varían estacionalmente. Capturamos aves en huecos o aberturas del docel de un bosque, adyacente a un bosque maduro durante el 2001 y el 2002 en Savannah River Site, Condado Garnwell, Carolina del Sur. A las aves le lavamos el buche para obtener información sobre los artrópodos utilizados como alimento durante la migración primaveral, durante la época reproductiva, post-reproductiva y durante la migración otoñal. Para determinar la disponibilidad de artrópodos en el follaje y en el suelo, usamos la técnica de cortar hojas con artrópodos y la de trampas de envases en el suelo. Los coleópteros y los hemípteros fueron utilizados como fuente de alimento, más de lo esperado tanto por aves que se alimentaron en el follaje como en los suelos, durante todos los periodos. Por su parte, los arácnidos y los himenópteros, fueron utilizados menos de lo esperado, basándose en la disponibilidad de estos durante todos los periodos de estudio. Las aves que se alimentaron en los suelos utilizaron homópteros y lepidópteros en mayor proporción que lo esperado, dada su disponibilidad, durante todos los periodos. Los artrópodos utilizados por las aves fueron consistentes desde la primavera hasta la migración otoñal, sin que hubiera desplazamiento o cambios estacionales en la dieta. Basado en estudios concurrentes, los ordenes de artrópodos más utilizados como alimento, estuvieron en similar o un poco más bajo en abundancia en los huecos del docel que en los alrededores de bosque maduro, pero las especies de aves se detectaron con mayor frecuencia en los huecos. Estos resultados sugieren que la alimentación preferencial de artrópodos por aves que se alimentan buscando insectos entre el follaje en habitats con huecos, reducen la densidad de artrópodos, o que el uso de los huecos o de bosque maduro no esta determinado por los recursos alimentarios. La abundancia de artrópodos a lo largo del rodal puede haber permitido que la aves permanecieran en los huecos o aperturas con alta densidad de plantas, en donde el follaje provee de protección contra los depredadores. [source] Mortality of older construction and craft workers employed at department of energy (DOE) nuclear sitesAMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 9 2009John M. Dement PhD Abstract Background The U.S. Department of Energy (DOE) established medical screening programs at the Hanford Nuclear Reservation, Oak Ridge Reservation, the Savannah River Site, and the Amchitka site starting in 1996. Workers participating in these programs have been followed to determine their vital status and mortality experience through December 31, 2004. Methods A cohort of 8,976 former construction workers from Hanford, Savannah River, Oak Ridge, and Amchitka was followed using the National Death Index through December 31, 2004, to ascertain vital status and causes of death. Cause-specific standardized mortality ratios (SMRs) were calculated based on US death rates. Results Six hundred and seventy-four deaths occurred in this cohort and overall mortality was slightly less than expected (SMR,=,0.93, 95% CI,=,0.86,1.01), indicating a "healthy worker effect." However, significantly excess mortality was observed for all cancers (SMR,=,1.28, 95% CI,=,1.13,1.45), lung cancer (SMR,=,1.54, 95% CI,=,1.24,1.87), mesothelioma (SMR,=,5.93, 95% CI,=,2.56,11.68), and asbestosis (SMR,=,33.89, 95% CI,=,18.03,57.95). Non-Hodgkin's lymphoma was in excess at Oak Ridge and multiple myeloma was in excess at Hanford. Chronic obstructive pulmonary disease (COPD) was significantly elevated among workers at the Savannah River Site (SMR,=,1.92, 95% CI,=,1.02,3.29). Conclusions DOE construction workers at these four sites were found to have significantly excess risk for combined cancer sites included in the Department of Labor' Energy Employees Occupational Illness Compensation Program (EEOCIPA). Asbestos-related cancers were significantly elevated. Am. J. Ind. Med. 52:671,682, 2009. © 2009 Wiley-Liss, Inc. [source] Mortality among workers at the Savannah River SiteAMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 12 2007David B. Richardson PhD Abstract Background Workers employed at the Savannah River Site (SRS) were potentially exposed to a range of chemical and physical hazards, many of which are poorly characterized. We therefore compared the observed deaths among workers to expectations based upon death rates for referent populations. Methods The cohort included 18,883 SRS workers hired between 1950 and 1986. Vital status and cause of death information were ascertained through 2002. Sex-specific standardized mortality ratios (SMR) were computed using U.S. and South Carolina mortality rates. SMRs were tabulated separately for monthly-, weekly-, and hourly-paid men. Results Males had fewer deaths from all causes [SMR,=,0.80, 90% confidence interval (CI): 0.78, 0.82], all cancers (SMR,=,0.85, 90% CI: 0.81, 0.89), and lung cancer (SMR,=,0.88, 90% CI: 0.82, 0.95) than expected based upon US mortality rates. The SMR for cancer of the pleura was 4.25 (90% CI: 1.99, 7.97) for men. The SMR for leukemia was greater than unity for monthly-paid (SMR,=,1.33, 90% CI: 0.88, 1.93) and hourly-paid (SMR=1.36, 90% CI: 1.02, 1.78) men. Female workers had fewer deaths from all causes (SMR,=,0.75, 90% CI: 0.69, 0.82) than expected, but more deaths than expected from cancer of the kidney (SMR,=,2.58, 90% CI: 1.21, 4.84) and skin (SMR,=,3.90, 90% CI: 2.11, 6.61). Conclusions While the observed numbers of deaths in most categories of cause of death were less than expected, there are greater than expected numbers of deaths due to cancer of the pleura and leukemia, particularly among hourly-paid male workers. It is plausible that occupational hazards, including asbestos and ionizing radiation, contribute to these excesses. Am. J. Ind. Med. 50:881,891, 2007. © 2007 Wiley-Liss, Inc. [source] Soil vapor extraction system design: A case study comparing vacuum and pore-gas velocity cutoff criteriaREMEDIATION, Issue 1 2006Kenneth L. Dixon Soil vapor extraction (SVE) systems are typically designed based on the results of a vadose-zone pumping test (transient or steady-state) using a pressure criterion to establish the zone of influence (ZOI). A common problem associated with pressure-based SVE design is overestimating the ZOI of the extraction well. As a result, design strategies based upon critical pore- gas velocity (CPGV) have become more common. Field tests were conducted at the Savannah River Site (SRS) to determine the influence of a vapor extraction well based upon both a pressure and pore- gas velocity design criterion. The results from these tests show that an SVE system designed based upon a CPGV is more robust and will have shorter cleanup times due to increased flow throughout the treatment zone. Pressure-based SVE design may be appropriate in applications where soil gas containment is the primary objective; however, in cases where the capture and removal of contaminated soil gas is the primary objective, CPGV is a better design criterion. © 2006 Wiley Periodicals, Inc. [source] The Use of Natural Systems to Remediate Groundwater: Department of Energy Experience at the Savannah River SiteREMEDIATION, Issue 3 2002Gerald C. Blount Natural remediation is moving toward the forefront as engineers clean groundwater at the Savannah River Site (SRS), a major Department of Energy (DOE) installation near Aiken, South Carolina. This article reviews two successful, innovative remediation methods currently being deployed: biosparging to treat chlorinated solvents and phytoremediation to address tritium in groundwater. The biosparging system reintroduces oxygen into the groundwater and injects nutrient compounds for in-situ remediation. The system has greatly reduced the concentrations of trichloroethylene (TCE) and vinyl chloride in wells downgradient from a sanitary landfill (SLF). Phytoremediation is an emerging technology that promises effective and inexpensive cleanup of certain hazardous wastes. Using natural processes, plants can break down, trap and hold, or transpire contaminants. This article discusses the use of phytoremediation to reduce the discharge of tritium to an on-site stream at SRS. © 2002 Wiley Periodicals Inc.* [source] | ||||||||||