Exchange Of Organochlorine Pesticides And Heavy Metals In Fauna And Other Media From Bays In Fujian And Hainan, South China.

One of the most potent chemical pollutants, organochlorine pesticides (OCPs), has become constituents of coastal environment in past decades due to their frequent usage in agriculture and vector control. Heavy metals such as mercury (Hg), cadmium (Cd), lead (Pb), chromium (Cr) and arsenic (As) exist only at a low concentration in the environment. However, their accumulation beyond the safety level invariably leads to huge environmental pollution and health hazards. Quanzhou, Xinghua, Xiaohai and Yangpu bays are economically and environmentally important subcomponents in South China Sea. However, over the last decade, we have witnessed an unprecedented pollution of these bays as a corollary of exponential growth in industry and agriculture. Most of industrial facilities are situated on the side of major rivers and coasts, thus domestic sewage and industrial wastewater contaminated with pesticides and heavy metals are discharged to local waters deliberately or accidentally, which lead to deteriorating environment quality of the coastal environment. Once discharged into the ocean, these chemicals disperse into three phases, viz., water, sediment and marine organisms. Although recent studies have attempted to address the organic and inorganic pollution in these areas, data on the coastal environment are still relatively limited and has not been adequately studied.Sediments (0-2 Cm and 2-10 cm depth) and sea water samples were collected from Quanzhou, Xinghua, Xiaohai and Yangpu Bays and fresh water samples were collected from relevant river inflows in each study area using standard methods. Marine organisms were collected from fish mongers from each study area. The marine fauna species were selected in view of their importance to local human consumers. Extracted OCPs and heavy metals of aforementioned samples were analyzed by GC-ECD and ICP-MS, respectively. Distributions and compositions of OCPs and heavy metals in each compartment and bioconcentrations in marine fauna were examined. In addition, results were cross-compared with other studies from Asia Pacific region. Estimated Daily Intakes (EDIs) of OCPs and accumulation concentrations of heavy metals in biological samples were compared with national and international standards to identify potential human health hazards.Results showed that all the compartments have been contaminated with OCPs and heavy metals. Compositions of DDTs such as the ratios of (DDE+DDD)/DDT and ratios of o,p'-DDT/p,p'-DDT indicated that aforementioned bays have been received fresh inputs of dicofol. The high levels ofγ-HCH from Quanzhou, Xinghua and Xiaohai Bays implied recent applications of lindane in the study areas. The concentration of the sum of DDTs (∑DDTs) exceeded that of the sum of HCHs (∑HCHs) in the samples analyzed and the organisms showed higher levels of∑DDTs than the Chinese government's first level criterion (10 ng/g) for marine biological quality (GB-18421-2001) but conformed to the first level criterion (20 ng/g) for∑HCHs. However, estimated mean daily intake of the pesticides was below the acceptable daily intake issued by FAO indicating minimal risk to the consumers. Among all the species from four bays studied Mugil cephalus had the highest concentrations of OCPs. Results revealed that not only the feeding habits but also other factors such as chemical composition may play a major role in high accumulation of OCPs.The average concentrations of each heavy metal studied in surface sediments from Quanzhou Bay exceeded the background values of heavy metals along the coastal regions of Fujian Province. The comparison of heavy metal concentrations from this study with that of marine sediment quality (GB 18668-2002) issued by China State Bureau of Quality and Technical Supervision showed that the overall average concentrations of all selected heavy metals in surface and bottom sediments from aforementioned bays met the primary standard criteria. Results further revealed that 100% of the sea water samples from both Quanzhou and Xinghua Bays exceeded the Grade 1 or Grade 2 of GB 3097-1997 for chromium, zinc and mercury indicating fresh input of those metals to the sea water. Concentrations of nickel in all sites from Xiaohai Lagoon exceeded the Grade 1 of sea water quality standard (GB 3097-1997). Among different sub groups, bivalves showed high accumulation levels of heavy metals in their body. The significantly elevated concentrations of As, Cd, and Zn found in shellfish likely resulted from the fact that their primary source of food is suspended matter, in particular, suspended fine sediment near or on the sea floor. It might also be partly attributed to the solubility of these trace metals in an aquatic environment. From the plots of PCA, the species in Xinghua Bay and Quanzhou Bay showed higher concentrations of As, Cd, Zn, Ni, and Cu compared to those in other two bays. Collectively, the present study revealed that commercially important edible marine organisms in Quanzhou, Xinghua, Xiaohai and Yangpu Bays in Southeast China have been contaminated by heavy metals to a greater degree and exceeded the recommended safety levels for consumption. Therefore, strict regulations for the usage of heavy metals and frequent monitoring and controlling programmes are needed to check heavy metal contamination of marine organisms in general and in the areas that may potentially cause greater threats to human and ecological health, in particular.