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(1 - 3 of 3)
- Title
- Evaluation and use of sediment toxicity reference sites for statistical comparisons in regional assessments,
- Description
- Sediment reference sites were used to establish toxicity standards against which to compare results from sites investigated in San Francisco Bay (California, USA) monitoring programs. The reference sites were selected on the basis of low concentrations of anthropogenic chemicals, distance from active contaminant sources, location in representative hydrographic areas of the Bay, and physical features characteristic of depositional areas (e.g., fine grain size and medium total organic carbon [TOC]). Five field-replicated sites in San Francisco Bay were evaluated over three seasons. Samples from each site were tested with nine toxicity test protocols and were analyzed for sediment grain size and concentrations of trace metals, trace organics, ammonia, hydrogen sulfide, and TOC. The candidate sites were found to have relatively low concentrations of measured chemicals and generally exhibited low toxicity. Toxicity data from the reference sites were then used to calculate numerical tolerance limits to be used as threshold values to determine which test sites had significantly higher toxicity than reference sites. Tolerance limits are presented for four standard test protocols, including solid-phase sediment tests with the amphipods Ampelisca abdita and Eohaustorius estuarius and sea urchin Strongylocentrotus purpuratus embryo/larval development tests in pore water and at the sediment-water interface (SWI). Tolerance limits delineating the lowest 10th percentile (0.10 quantile) of the reference site data distribution were 71% of the control response for Ampelisca, 70% for Eohaustorius, 94% for sea urchin embryos in pore water, and 87% for sea urchins embryos exposed at the SWI. The tolerance limits are discussed in terms of the critical values governing their calculation and the management implications arising from their use in determining elevated toxicity relative to reference conditions., Cited By (since 1996):19, Rocks and Cores, CODEN: ETOCD, ,
- Author
- Hunt, Anderson, Phillips, Newman, Tjeerdema, Fairey, Puckett, Stephenson, Smith, Wilson, Taberski
- Date
- 2001-01-01T00:00:00Z
- Title
- Trace metals in mussels transplanted to San Francisco Bay,
- Description
- Mussels (Mytilus californianus) transplanted to San Francisco Bay exhibited elevated trace metal concentrations compared with those in other mussel watch studies on the west coast of the United States. The highest concentrations of Ag, Cu, Hg, Mn, Pb and Zn were at the South Bay stations, and often in the Redwood Creek area. Ag and Hg concentrations were linearly correlated with station distance from the North Bay (San Pablo Bay), indicating that the South Bay is a major reservoir of these pollutants within San Francisco Bay. © 1986., Cited By (since 1996):7, CODEN: ETOCD, ,
- Author
- Smith, Stephenson, Flegal
- Date
- 1986-01-01T00:00:00Z
- Title
- Determination of tributyltin in tissues and sediments by graphite furnace atomic absorption spectrometry,
- Description
- A method for the determination of tributyltin (TBT) in tissue and sediments has been developed for environmental samples. The technique involves extraction with methylene chloride and isolation of TBT from mono- and dibutyltin with a sodium hydroxide wash. The TBT is then back extracted and converted to elemental Sn with nitric acid. Analysis is by Zeeman graphite furnace atomic absorption spectrophotometry. Recoveries of spiked samples were between 99 % and 111% for mussel and fish tissues and 72% and 99% for various sediments. The limit of quantification was 0.0025 μg/g for tissue (on a wet weight basis). This technique was developed in response to our need to process large numbers of environmental samples with a minimum time investment., Cited By (since 1996):9, ,
- Author
- Stephenson, Smith
- Date
- 1988-01-01T00:00:00Z