第二松花江鱼及蚌汞含量现状及演变规律

Mercury contamination of fish in the Di’er Songhua River of China: the present station and evolution law

为了解第二松花江在彻底切断汞污染源20年后的鱼体汞污染现状,于2003-2004年共采集鱼样10种158条及蚌样28个,测定鱼和蚌中的总汞含量,并搜集20世纪70年代第二松花江鱼样和蚌样的汞污染资料,分析其演变规律。测定表明,各种鱼类的总汞平均含量未达到背景值,有部分样品超标。鱼体汞含量,从上游到中下游,呈增长趋势,之后又向下游递减。该江目前鱼类总汞污染水平主要受沉积汞影响。各种不同鱼类间,底栖鱼类的总汞含量高于生活在水层中上部的鱼类,肉食性鱼类的汞含量高于杂食性和植食性鱼类。在所测定的鱼类中,只有鲫鱼的汞含量与其体长和体质量有相关关系。所测定的鱼样中,有部分鱼样的总汞含量超过了国家食品卫生标准,这说明第二松花江的汞污染还没有完全消除。

In 2003-2004, 158 fish and 28 mussels were collected from 6 sample spots from the upstream to downstream of the Di’er Songhua River of China and the total mercury content was detected. The data about the mercury pollution status of fish and mussels in that river in the 1970s were also gathered for the purpose of the analysis on the trend and law of mercury concentration change in the fish and mussel. The range of mercury concentrations in fish and mussel was 0.02~0.66 mg·kg-1and 0.002~0.056 mg·kg-1, re-spectively. In the investigation, the results indicated that the average mercury value in fish didn’t reach the background value of that which was contradictory to the predicted one. From upstream to downstream, the average mercury concentrations of fish increased with the increase of the distance to the headstream, then decreased after the sample spot in Wujiazhan town located at the down-stream of the river. The fact illuminated that the main and important mercury pollution source for fish was the release of mercury form the sediment in that river with the transference of the sediment to the downstream. In the different species of fish, the concen-tration of mercury in Parasiburus asvtus was the highest one in comparison with that of the other fish which showed that the law for mercury distribution in fish was: the concentration of mercury in fish in the bottom of the river>that of fish in the surface of the river; and that of predatorial fish>that of herbivorous fish. In this study, the mercury concentration had no relationship with the length and weight in all kinds of fish except for Carassius auratus gibeliv, for which the reason should be investigated in the further research. In the investigation, there were a mount of fish whose mercury value exceeded the criterion for that of fish. It was suggested that the mercury contamination in the Di’er Songhua River had not completely been removed.