长牡蛎对水环境中汞(II)的富集及其甲基化研究

Study on mercury (II) accumulation and its methylation in water environment by Crassostrea gigas

中文关键词:  牡蛎器官  汞甲基化  甲基汞  污染评价

英文关键词:oyster organs  mercury methylation  methylmercury  pollution assessment

中文摘要:

      目的 研究牡蛎各器官对海水环境中无机汞的富集与排出及转化与代谢。方法 以长牡蛎(Crassostrea gigas)为研究对象,在不同浓度HgCl₂海水胁迫与净化一定时间,分析腮、内脏团等各器官对汞富集与排出、汞甲基化与代谢,评价代谢后各器官中甲基汞的污染指数。根据美国 EPA和 WHO 推荐的甲基汞参考摄入量,给出建议食用量。结果 牡蛎对水体中无机汞的富集速率大于汞的甲基化速率,进入体内部分汞被甲基化转化为甲基汞与外界无机汞胁迫浓度呈正相关；牡蛎腮中甲基汞的含量较内脏团、闭壳肌、外套膜中的含量更高。当海水中无机汞浓度到65.20 ng/L时,代谢30天后,内脏团、闭壳肌、外套膜中甲基汞污染评价为正常,腮中甲基汞污染评价稍高处于轻度污染。根据美国 EPA和 WHO 推荐的甲基汞参考摄入量,在海区中总汞含量低于245.20ng/L时,将牡蛎置于低汞浓度的海水中(小于45.20 ng/L,接近GB3097-1997一类水质对总汞的限量要求)经过一定时间代谢后,可食部分符合我国国家标准、行业标准和Codex的标准中对于甲基汞限量要求。结论 总汞在牡蛎各器官的富集和排出规律符合Kahle双箱动力学模型,各器官内对汞的甲基转化与代谢也可用此模型来模拟计算。本研究可为准确评估汞污染对牡蛎安全生产与风险提供科学依据与数据支持。

英文摘要:

      Objective To study the accumulation and conversion to methylmercury of mercury(II) in the aquatic environment of Crassostrea gigas. Method Crassostrea gigas was used to analyze the accumulation and excretion of mercury, mercury methylation and metabolism in various organs such as gills and visceral masses, which was farmed under different concentrations of HgCl₂ seawater stress and purification for a certain period of time, and then the pollution index of methylmercury in various organs after metabolism were calculated to evaluate the safety of the oyster. Recommended consumption is given based on the recommended reference intake for methylmercury by the United States EPA and WHO. Results The accumulation rate of inorganic mercury in the seawater column was greater than the methylation rate of mercury in the tissue of oysters, and the methylation of portion mercury into methylmercury was positively correlated with the concentration of inorganic mercury stress. The content of methylmercury in oyster gills was higher than that in visceral mass, muscle, and mantle. When the concentration of inorganic mercury in seawater reached 65.20 ng/L, after 30 days of metabolism, methylmercury pollution in visceral mass, muscle and mantle was evaluated as normal, and methylmercury pollution in gills was slightly. According to the methylmercury reference intake recommended by the EPA and WHO in United States, when the total mercury content in the sea area is less than 245.20 ng/L, the oysters were placed in nature seawater with low mercury concentration (less than 45.20 ng/L, close to the limit requirements of GB3097-1997 class Ⅱ of water quality for total mercury) after a certain period of metabolism, and the edible part oysters the requirements for methylmercury limit in China"s national standards, trade standards and Codex standards. Conclusion The results showed that the accumulation and excretion of total mercury in oyster organs were in line with the Kahle double-box kinetic model, and the methyl conversion and metabolism of mercury in each organ could also be simulated and calculated by this model. This study can provide scientific basis and data support for accurately assessing the impact of mercury pollution on oyster safety and risk.