| Recent years, economics in Beibu Bay coastal areas developed rapidly, resultinggrowing marine pollution. Evaluation based on molecular biomarkers can reflect toxiceffects of pollutants’ combined pollution on marine organisms, which is especiallysuitable for early warning of environmental pollution. Integrated biomarker responseindex (IBR) is widely used for its high flexibility and visualization. But it usuallyadopt single species to evaluate the extent of comprehensive pollution.Base on above, marine bivalves (Paphia undulata and Meretrix meretrix) andsediment samples are collected from7sampling sites distributed in the intertidal zonealong the Beibu Bay in the autumn of2011. Contents of several contaminants aredetermined, such as7types of heavy metal (Hg、As、Cu、Pb、Zn、Cd、Cr), sulfide(only sediments determinated), total petroleum hydrocarbon (TPH), polychlorinatedbiphenyls (PCBs) and Nonylphenol (NP) in the soft tissue of bivalves and sediments.Meanwhile,9biomarkers are assayed in the gills and digestive glands of P. undulataand M. meretrix. They are superoxide dismutase (SOD), catalase (CAT), glutathioneperoxidase (GPx), glutathione-S-transferases (GST), glutathione (GSH)、oxidizedglutathione (GSSG), thibabituric acid reactive substance (TBARs), metallothionein(MTs), and acetylcholinesterase (AChE). The study analyzed the biomarkers respondto pollutions and select sensitive biomarkers to form three evaluation index systemsthat was suitable for indicating the comprehensive pollution level of Beibu Bay. Then,evaluating the integrated pollution levels in Beibu Bay according to the improvedintegrated biomarker indexes (Integrated Biological Responses version2, IBRv2),analyzing and contrasting the application effects in the benthic environmental qualityassessment of the systems based on single species and double species and finallydetermining a biomarker index system which is quite suitable for regionalcomprehensive evaluation study. The main conclusions obtained were as follows:（1）Due to the impacts of factors like sediments, pollution emissions, there arelarge differences in spatial distribution of each pollutant content among sediments, P.undulate and M. meretrix in Beibu Bay intertidal. In sediments, the highest value of most pollutants appear in S2(Yingpan Port) and S5(Fangcheng East Port). The highvalues of the two bivalves soft tissue pollutant are mainly distributed in S6(FangchengWest Port), which is not consistent with pollutant spatial distribution law insediments.（2）9biomarkers levels in P. undulate and M. meretrix have apparentdifferences in the spatial distribution (except MTs in the gills of M. meretrix), andmost biomarkers response value are different for different species and organs.Compared to control stations (S1, Jianghong coast), multiple biomarkers in the other6stations showed significant induction or inhibition effect.（3）There are significant correlations between multiple biomarkers andcontaminant levels of organism (P. undulate and M. meretrix), base on which weselect three evaluation index systems that are suitable for integrated pollution levels inBeibu Bay. The frist set of combination is consist of SODg, AChEg, GSTg, GSHdg,GSSGdg, CATdgin P. undulate (subscript g and dg mean gill and digestive glandsrespectively, the same below). The second set of combination is consist of GSHg,SODg, GSTg, TBARsgand GSTdg, SODdgin M. meretrix. The last set of combinationis consist of SODgin P. undulate and SODg, GSHg, GSTg, TBARsg, GSTdgin M.meretrix.（4）IBRv2values of7stations in Beibu Bay, calculated according to the3setsof biomarker combinations, show that biomarker index system evaluation results ofdifferent biological sources are not consistent. The IBRv2calculated by biomarkerssystem based on double biological screening is more objective to assess Beibu Baysediment integrated pollution levels. The order of integrated pollution levels in BeibuBay ranked from high to low as follows: S2（Yingpan Port）＞S3（Xichang coast）＞S5（Fangcheng East Port）＞S6（Fangcheng West Port）＞S4（Xiniujiao coast）＞S7（Moon Port）＞S1（Jianghong coast）。... |
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