Heavy Metal Accumulation in Subsurface, Estuarine Sediments and Inferences for Anthropogenic Enrichment: N.W. Florida Coast

by Gregory W. Stone, Louisisana State Univ, Baton Rouge, United States,
J. S. Watson, Louisisana State Univ, Baton Rouge, United States,
J. T. Walker, Louisisana State Univ, Baton Rouge, United States,
J. P. Morgan, Louisisana State Univ, Baton Rouge, United States,

Document Type: Proceeding Paper

Part of: Coastal Zone '93


In an attempt to quantify the degree of contamination and the thickness of the contaminated subsurface sedimentary wedge, approximately 100 samples were extracted from the cores and subjected to grain-size and heavy metal (Al, Fe, Cd, Cr, Cu, Co, Pb, Mn, Ni, Zn) analyses. Detailed lithofacies descriptions in addition to the composition and texture of sediments in the cores permitted identification of Plio-Pleistocene and Holocene boundaries. Metal concentrations found in theses sediments were used as background trace metal levels in natural (uncontaminated) material where the subsurface remained undisturbed by human activity (dredging in, spoil deposition, etc.) Anthropogenically-induced, metal enrichment was clearly evident in the bayou, although the thickness of the contaminated wedge varied due to sedimentation rates, flushing capacity, local geology of the watershed and the degree of industrialization or urbanization. The principal advantage of this approach over other (e.g. normalization), is that the clean Holocene sediment, which is primarily homogeneous, monomineralic (quartz sand) material, can be readily sampled progressively upcore resulting in the precise location of the contaminated sedimentary wedge.

Subject Headings: Wedges | Metals (chemical) | Subsurface environment | Thickness | Groundwater pollution | Dredged materials | Water pollution | Heavy metals | Alabama | Florida | United States

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