Metals in sediments of the Upper Laguna Madre

The Laguna Madre system is the largest hypersaline coastal basin in the Uni ted States. Surface sediments from 22 Upper Laguna Madre (ULM) sites were a nalyzed for grain size and metals (Cd, Cu, Ba, Cr, Mn, Ni, Pb, V, Zn, Fe, a nd Al) to assess the extent of contamination in the area. Sediments were fo und to consist mainly of sand texture. Clay and silts were minor constituen ts (<10%) of the sediments. Anomalies in metal concentrations were found at some sites and were related to probable sources, i.e., recreational and in dustrial activities. Concentrations of metals were normalized to grain size , Al, and Fe to distinguish natural and anthropogenic sources. Most metals showed positive correlations (p < 0.001) with Fe and Al, suggesting a natur al variability of metal concentrations in sediments. Concentrations of meta ls, except Cd and Ph, at most sites were found to be below threshold concen trations thought to produce toxic effects in marine and estuarine organisms . (C) 1999 Elsevier Science Ltd. All rights reserved.