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A SUMMARY OF TOTAL MERCURY CONCENTRATIONS IN FLORA AND FAUNA NEAR CONTAMINANT SOURCES IN THE GULF OF MEXICO
LEWIS, M. A. AND C. A. CHANCY. A SUMMARY OF TOTAL MERCURY CONCENTRATIONS IN FLORA AND FAUNA NEAR CONTAMINANT SOURCES IN THE GULF OF MEXICO. CHEMOSPHERE. Elsevier Science Ltd, New York, NY, 70(11):2016-2024, (2008).
This report summarizes total mercury concentrations for environmental media collected from near-coastal areas including those impacted by contaminant sources common to the Gulf of Mexico. Water, sediment, fish, blue crabs, oysters, clams, mussels, periphyton and seagrasses were collected during 1993-2002 from targeted areas affected by point and non-point source contaminants. Mean concentrations in water and sediment were 0.02 (± 1 standard deviation = 0.06) µg/l and 96.3 (230.8) ng/g dry wt, respectively. Total mercury concentrations (ng/g dry wt) averaged 23.1 (two seagrass species), 220.1 (oysters), 287.8 (colonized periphyton), 604.0 (four species of freshwater mussels), 772.4 (brackish clam), 857.9 (blue crabs) and 933.1 (nine fish species). Mean concentrations in fish, blue crabs, brackish clams and mussels were significantly greater than those in sediment, seagrass, colonized periphyton and oysters. Spatial and biotic variability in results limited most generalizations concerning the relative mercury contributions of different stressor types. However, mercury concentrations were significantly greater for some biota collected from areas receiving wastewater discharges and golf course runoff (fish), agricultural runoff (oysters) and urban stormwater runoff (colonized periphyton and sediment). Marine water quality criteria and proposed sediment quality guidelines were exceeded in 1 to12 % of the total samples. At least one seafood consumption guideline, criteria or screening value was exceeded in edible tissues of blue crabs (6% total samples) and fish (8-33% total samples). All residues were less than the U.S. FDA action limit of 1.0 ppm. Mercury concentrations in water and oyster tissues were less than the few reported toxic effect concentrations.