Assessment of halogenated aromatic compounds contamination in the Galveston Bay ecosystem /
This study was designed to assess the extent of toxic halogenated aromatic hydrocarbons (HAHS) in sediment and selected organisms from Galveston Bay, Texas. Contamination of bottom sediments by HAHs was observed throughout Galveston Bay. HAH concentrations were elevated at locations at or near the...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1996.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=739363501&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | This study was designed to assess the extent of toxic halogenated aromatic hydrocarbons (HAHS) in sediment and selected organisms from Galveston Bay, Texas. Contamination of bottom sediments by HAHs was observed throughout Galveston Bay. HAH concentrations were elevated at locations at or near the upper Houston Ship Channel between Baytown and the Port of Houston. Lower HAH concentrations were observed for all open bay samples collected away from input sources. PCDD/PCDF in sediments showed patterns typical of atmospheric deposition throughout the bay system while evidence of 2,3,7,8-TCDD and 2,3,7,8-TCDF contamination was found localized within the Houston Ship Channel area near Greens Bayou. The historical chronology of HAH contamination in Offats Bayou indicates that concentrations of PCDD/PCDF, and PCBs and DDTs have been declining for the last 20-30 years. HAHs were present in all the organisms analyzed. Species differences in HAH concentrations were related to the general feeding habits of the organisms, with Hardhead catfish livers having the highest HAH concentrations, followed by Blue crabs and American oysters. Organisms also showed spatial differences with a general decreasing trend between the more contaminated Ship Channel samples and the relatively unimpacted samples from Hanna's Reef and Carancahua Reef, respectively. When the 2,3,7,8-TCDD toxic equivalents were investigated, Blue crabs had TEQ concentrations that generally exceeded the 7 pg/g wet weight consumption advisory level proposed by EPA for fish and shellfish screening. In addition, crabs analyzed from the Ship Channel station exceeded the 70 pg/g wet weight TEQ concentration established as a limit for a possible consumption ban. The uptake and deputation of RAHs by oysters was further examined through the analysis of previously transplanted oysters in Galveston Bay. 2,3,7,8-TCDD and TCDF and all the planar PCB congeners were bioaccumulated by the oysters. Accumulation was selective and favored the lower chlorinated isomers and congeners, however, none of the compounds investigated reached equilibrium concentrations during the 48 day exposure experiment. When the organisms were back-transplanted to their original location, 2,3,7,8TCDD, 2,3,7,8-TCDF, PCB 77, and PCB 81 were depurated at similar rates while the penta- and hexa-chlrorinated planar PCBs were lost at considerably lower rates. |
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| Item Description: | Vita. "Major Subject: Oceanography". |
| Physical Description: | xxv, 248 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references : pages 221-239. |