广东沿岸牡蛎体内HCHs的时空分布特征

摘要

于1989—1993和2003—2012年间每年春季采集广东沿岸的近江牡蛎样品(Crassostrea rivularis Gould),用气相色谱法测定其中六六六(HCHs)的含量,并结合1980—1985年广东省海岸带污染调查的相关数据,分析和探讨了广东沿岸牡蛎中六六六(HCHs)的时空分布特征,并评价了其食用风险与生物质量。结果表明,广东沿岸牡蛎体内HCHs含量范围在未检出~42.4 ng/g之间,平均值为(1.70±6.13) ng/g,总体检出率为92.3%。广东沿岸海域牡蛎体内HCHs自20世纪80年代初期禁用六六六以来先快速下降,90年代以后降幅放缓并逐渐趋于平稳,30年间HCHs含量降低至20世纪80年代初期的0.06%。在空间上,80年代初期珠江口岸段HCHs含量远高于粤东和粤西岸段,随着时间的推移,粤西岸段HCHs的含量比逐渐升高,而珠江口的则逐渐降低,三者含量差距缩小。HCHs组分特征分析认为,80年代末期以来,广东沿岸海域牡蛎体内HCHs主要来源于历史使用残留,但在20世纪90年代到21世纪初期期间,广东沿岸地区牡蛎体内HCHs可能源于林丹的使用。评价结果表明,所有样品中HCHs均远低于中国相关残留限量标准,但1989年有75.0%的样品中HCHs超出中国《海洋生物质量》一类标准；通过食用牡蛎,每日HCHs摄入量在0.11~83.62 ng/(kg·d),远低于世界粮农组织(FAO)和世界卫生组织(WHO)规定的每日允许摄入量。%Mussels are often used as sentinel organisms to monitor the presence of environmental contaminants. We measured the hexachlorocyclohexane (HCH) content in the soft tissue of oyster (Crassostrea rivularis Gould) samples collected from the Guangdong coast in 1989-1993 and 2003-2012 using gas chromatography. Using re-lated data taken from the Pollution Investigations Program along Guangdong’s coastal zone during 1980−1985, we analyzed the residue levels, spatial and temporal trends, and composition of HCHs in oysters. In addition, we as-sessed the food safety and biological quality of HCHs in oysters. HCHs were detected in 92.3%of the samples at concentrations ranging from below the limit of detection to 42.4 ng/g(mean: 1.70 ng/g wet weight basis). HCH content has declined over time since the early 1980s, but the rate of decline slowed and levels have remained con-stant since the early 1990s. In general, the HCH content has decreased by 99.94% over the last 30 years. In the early 1980s, the HCH content in oysters in the Pearl River Estuary was much higher than in the East and west Guangdong coasts, but the difference in HCH content between these three coasts has gradually decreased over time. The composition of HCH compounds implies that the HCHs are primarily derived from historical usage, but the lower ratios of α-HCH/γ-HCH (0.53-1.11) indicate that there was likely fresh input of lindane between the 1990s and early 2000s. The HCH residue levels in all oyster samples were far below the maximum residue limit in China, although 75.0%of oyster samples collected in 1989 exceeded the requirement of the first grade of the Na-tional Marine Biological Quality Standard of China (GB18421-2001). The daily intake of HCHs by residents along the Guangdong coast via consumption of seafood products ranged from 0.11 to 83.62 ng/(kg·d), which is much lower than the Acceptable Daily Intake established by the Food and Agriculture Organization of the United Na-tions/World Health Organization.