Document Type

Report

Department/Program

Virginia Institute of Marine Science

Publication Date

6-1982

Series

Special scientific report No. 106

Abstract

This report aims to provide new information that meets selected objectives of the EPA-States Taxies Plan of Action: i.e. (1) to determine the state of the Bay with respect to the distribution and concentration of selected metals in suspended material and fluid mud; (2) to establish the temooral variations of sediment and metal loading: (3) to identify potential zones of metal accumulation and trace their transport routes, and (4) to provide recommendations for monitoring contaminated sediment.

Field observations provide longitudinal coverage of the Bay with transects into Baltimore Harbor and Hampton Roads. They include contrasting conditions of seasonal high-low river discharge and sediment influx, as well as neap-spring tide range and oxygenated-anoxic water. Suspended material collected on Nuclepore filters, was analyzed by flame AA for Fe, Mn and Zn and by flameless .'A.A for As, Cd, Cu, Hg, Ni, Pb and Sn. Laboratory procedures followed EPA quality control standards using USGS Standards. The survey occupied 122 stations, accomplished 5,576 measurements including 633 analyses of 6 to 11 metals in suspended material and fluid mud.

Physical, chemical and sedimentological conditions for transport and accumulation of taxies in the Bay are variable with time and distance seaward. Bay water is partly-mixed, well-buffered against pH change and well-oxygenated except in summer when near·-bottom water of the axial basin is anoxic. Salinity and sediment influx vary seasonally with river discharge and form steep seaward gradients near the inner limit of salty water. Characteristics of suspended material define three broad zones: (1) the turbidity maximum (stations 12-18) with high suspended loads, fine particle size and low organic percentages: (2) the central Bay (stations 8-11) with low suspended loads, coarse particle size and high organic percentages; (3) the near-entrance reaches (stations 1-7) with intermediate suspended loads, moderate particle size and organic percentages. Sediment in deeper parts of the central Bay is fine-grained, moderately organic and depositing relatively fast.. These conditions favor accumulation of metals and fluid mud.

DOI

http://dx.doi.org/doi:10.21220/m2-s66r-4751

Keywords

Heavy metals -- Environmental aspects -- Chesapeake Bay (Md. and Va.); Estuarine sediments -- Chesapeake Bay (Md. and Va.); Suspended sediments -- Chesapeake Bay (Md. and Va.); Sediments (Geology); Coastal sediments; Estuarine oceanography

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