Bioaccumulation Factors for Polychlorinated Biphenyls in Hardhead Catfish and Atlantic Croaker in the Houston Ship Channel
Concentrations of polychlorinated biphenyls (PCBs), a group of compounds known to be carcinogenic, in water and fish samples were studied in the Houston Ship Channel and Galveston Bay to determine a bioaccumulation factor (BAF, measured in L/kg lipid) for common fish species. The United States Environmental Protection Agency (USEPA) employs the use of a simple BAF parameter in water quality regulation. The objective of the study was to test the validity of this assumption. Water PCB concentration was found using a high-volume sampling technique, where suspended and dissolved PCBs were captured using 1 µm Glass Fiber Filters (GFFs) and XAD-2 resin columns, respectively. Hardhead Catfish (n=21 samples for 2008 study, n=68 samples for 2002 study) and Atlantic Croaker (n=14 samples for 2008 study) were filleted for tissue analysis. A general decline in PCB levels from 2002-2003 to 2008 across all media was found in the studied area. In the 2008 study, 96% (n=25) of the stations sampled exceeded the PCB standard for fish tissue and/or water, set by Texas Department of State Health Services (TDSHS) and Texas Commission on Environmental Quality (TCEQ). A strong linear correlation was found between total water concentration and the lipid-normalized tissue concentration of PCBs in Atlantic Croaker (R2=0.696, p<0.05), while no correlation was found for PCB content in tissues obtained from Hardhead Catfish (R2=0.022, p=0.563). The BAF values calculated for the Atlantic Croaker had a lower mean and smaller range (2.41·106, 1.19·106-4.12·106), in comparison to those calculated for the Hardhead Catfish (7.02·106, 8.50·105-5.82·107) in the 2008 data set. This correlated with 2002-2003 study results for BAF in Hardhead Catfish (5.65·106, 5.37·105-3.04·107). No correlation (R2=0.0029, p=0.862) was found between the BAF of Atlantic Croaker and Hardhead Catfish at the common sampling sites in the 2008 study. We found that a linear statistical model was not suitable for determining a BAF that can accurately predict fish tissue concentration from water concentration, or vice versa, for both species.