| Abstract: | Sixty-two cores ranging in length from 33 to 1002 cm were collected from the tidal Potomac system and from selected tributaries downstream from the local head-of-tides between June 1978 and July 1981. Segments from selected depths below the sediment surface have been analyzed for a variety of constituents, including lead-210, trace metals, nutrients, and particle size. The core sites were positioned throughout the hydrologic divisions and geomorphic units of the tidal Potomac system and in water depths ranging from 1 to 30 cm. Cores collected by divers were mostly for historical deposition-rate computations. Vibra cores, as much as 12 m long, were collected primarily to provide data on long-term (pre-historical) sedimentation rates and conditions. Benthos cores were used to provide samples rapidly in locations where divers were not available. Alpha counting methods were used to determine the polonium-210 radioactivity and secular equilibrium was assumed between lead-210 and polonium-210. The alpha decay of polonium-210 provides a measure of the lead-210 radioactivity of the lead-210 produced by in-situ decay of radium-226 in the sediment column (background lead-210) and the lead-210 from external sources (unsupported lead-210). Only the unsupported lead-210 was used in computations of the deposition rate. The count error is based on the counting statistics alone and varies from 3 to 5% of the total number of counts. The background level of lead-210 in tidal Potomac system sediment cores usually is based on in-situ measurements of total lead-210 at depths below which no unsupported lead-210 is believed to be present, and the lead-210 concentrations are relatively constant. (Lantz-PTT) |
| Genre: | USGS Numbered Series |
| ProdID: | 13824 |
| Citation Author: | Glenn, J. L.; Martin, E. A.; Rice, C. A. |
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| Citation Language: | ENGLISH |
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| Citation Phsyical Description: | iv, 73 p. :maps ;28 cm. |
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| Citation Publisher: | U.S. Geological Survey, |
| Citation Series: | Open-File Report |
| Citation Series Code: | OFR |
| Citation Series Number: | 86-318 |
| Citation Search Results Text: | Sediment data for computation of deposition rates in the tidal Potomac system, Maryland and Virginia; 1986; OFR; 86-318; Glenn, J. L.; Martin, E. A.; Rice, C. A. |
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| Citation Year: | 1986 |
| Type: | citation/reference |
| Text: | Sediment data for computation of deposition rates in the tidal Potomac system, Maryland and Virginia; 1986; OFR; 86-318; Glenn, J. L.; Martin, E. A.; Rice, C. A. |
| URL (THUMBNAIL): | http://pubs.usgs.gov/of/1986/0318/report-thumb.jpg |
| URL (DOCUMENT): | http://pubs.usgs.gov/of/1986/0318/report.pdf |
| Date Other: | Sat, 1 Jan 1994 00:00 -0600 |
| Publisher: | U.S. Geological Survey, |
