| Research on global environmental change is one of the most active major frontiers in natural sciences. Persistent organic pollutants (POPs) have become one of the three major environmental issues effected human survival and health in the21st century. Research on sediment records of POPs will help to understand regional pollution history. Domestic and foreign scholars have carried out extensive research. On China’s coastal areas, numerous literatures on POPs in the Bohai Sea, Yellow Sea, East China Sea and the Pearl River Delta of South China Sea have been published, while litter reports on POPs were found in the Beibu Gulf, South China Sea. In2008, The "Beibu Gulf Economic:Zone Development Plan" was raised as a national strategy, regional economy has experienced rapid growth. Therefore, research on sedimentary records of POPs in the Beibu Gulf can write major historical events, and identify the environmental pollution. In this study, OCPs and PAHs were determined in a sediment core from the Beibu Gulf. Organic pollution history over the past60years was restored by210Pb dating to identify the sources of OCPs and PAHs, and to explore the relationship between the regional economic development, human activities and PAHs. By a constant initial210Pb concentration (CIC) model, the sedimentary rate of the core is0.86cm yr-1, which was between the estuary and the marine areas in the Beibu Gulf. The deposition of50cm was between the computed1951and the core-top2010.The total OCPs level in the sediment core of the Beibu Gulf varied from0.93to26.6ng g-1(average3.48ng g-1).26OCPs were detected in the core samples. DDTs were found to be the most abundant compounds, accounting for40%of the total OCPs. Levels of DDTs began to increase in1980. The max level was found in2010. In1983, DDTs were banned from being used in China. The fact that DDTs levels didn’t decrease after the ban suggests their levels are controlled by several processes, such as new input, land reclamation, soil runoff, and use of DDT-based antifouling paint. The vertical profile of HCHs is characterized with alternately high-low fluctuation. The peak value of HCHs was observed in1984. The temporal distribution of α-HCH/γ-HCH and γ-HCH/HCHs ratios suggested fresh inputs of lindane recently. The historical trend of CHLs and endosulfan levels agrees with their application history in China. The ratios of TC/CC exhibited an increasing trend recently, suggesting fresh inputs of chlordane.The total PAHs levels in the Beibu Gulf were10.5-87.1ng g-1(average41.1ng g-1).3ring PAHs dominated (in particular Phe) in the total PAHs. The max level was observed in2010. Overall, total PAHs showed an increasing trend with three peaks occurred in the mid-1980, mid-1990s, and mid-2000s, which were consistent with the regional exploitation period:1983-1984,1990-1999and2003. The vertical profiles of different ring PAHs show an increasing trend of4ring PAHs and a sharp increase in2005of5-6ring PAHs, which was different from a relative constant with little fluctuations in the past60years of2-3ring PAHs. Different from oil and natural gas in developed regions, coal combustion has always been a significant energy consumption pattern in the past30years in the Beibu Gulf. Source apportionment indicated that PAHs were pyrogenically derived. Positive correlations were found between PAH level profiles and socioeconomic indexes (such as GDP, energy consumption and population). Their overall increasing trends are similar. |
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