Bioassay, Chemical Analyses, and Statistical Analyses of Samples obtained from Galveston Harbor, Texas
Horne, J. D.
Swirsky, M. A.
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In May 1979, Contract No. DACW64-79-C-0037, for performance of bioassays and bioaccumulation studies, chemical analyses of sediments, seawater and elutriate materials, and appropriate statistical analyses of samples obtained from the Galveston Harbor and Sabine-Neches Waterway channels, was awarded to NUS Corporation by the Army Corps of Engineers, Galveston District. These studies are part of a continuing evalution of the potential environmental effects of proposed ocean disposal of dredged materials and are required for compliance with provisions of Section 103 of the Marine Protection, Research and Sanctuaries Act of 1972 (PL 92-532). This final report presents the results of dredged material evaluations for the Galveston Harbor Channel project area. Channel sediments collected at designated locations in the project area were evaluated by bioassays of liquid, suspended particulate, and solid phase materials. A variety of sensitive marine vertebrates and invertebrates were used, including a fish, a crustacean, a crustacean postlarva (zooplankton), a polychaete, and a bivalve. Evaluative procedures were as established in Ecological Evaluation of Proposed Discharge of Dredged Materials into Ocean Waters (EPA/CE, 1977). The results of these bioassays showed that sediments of the Galveston Harbor Channel pose no serious or unacceptable hazard to the marine environment. The potential for bioaccumulation of selected pesticides, polychlorinated biphenyls (PCB's), heavy metals and petroleum hydrocarbons in tissues of marine organisms was evaluated by laboratory methodologies. The results of tissue analyses of sandworms and hard clams exposed to Galveston Harbor Channel sediments indicated that the concentration of all constituents analyzed was not significantly different between animals exposed to test and reference materials. There was no indication that the test animals had accumulated constituents of interest from the test materials to a greater extent than from the reference sediment. Chemical analyses for a variety of heavy metals, selected pesticides and PCB's, nitrogen derivatives, and oil and grease residues in sediments, seawater and elutriate materials were performed to define ambient concentrations of these constituents in the project environs. Many constituents exhibited no concentration above a quantifiable analytical detection limit. Several constituents (notably Aroclor 1254, arsenic, chromium, copper, lead, nickel, zinc, ammonia, nitrate, TKN, and oil and grease in sediments, and ammonia and TKN in seawater) displayed a general trend toward highest concentrations at shoreward sampling areas. Mercury was present in sediment materials throughout the project area, but was not found in excessive concentrations. The concentrations of oil and grease residues in seawater samples were highest at seaward sampling areas. It was conservatively determined that mercury concentrations in elutriate materials from all channel sampling areas would exceed the established marine water quality criterion; however, the initial mixing zone available at the designated disposal area is adequate to achieve the required dilution factors.