巢湖杭埠-丰乐河汞的污染特征及生态风险

通过对水样、沉积物和背角无齿蚌中汞含量的测定，研究杭埠-丰乐河汞的污染特征，并利用单项污染指数法、地累积指数法评估了汞的生态风险.结果表明：水样总汞的浓度为0.04～0.20μg/L（均值为0.10μg/L），H5、H9、F2、S4和S5处水样中汞含量超过地表水Ⅲ类限值.沉积物中汞、甲基汞含量分别为29.13～251.49μg/kg（均值为65.42μg/kg）和0.22～3.31μg/kg（均值为0.68μg/kg），H5、H9和F2处沉积物中汞为轻度污染，S4、S5为偏中度污染，工业排污是主要污染来源.背角无齿蚌中汞、甲基汞含量分别为101.34～171.15μg/kg（干重）和54.22～89.63μg/kg（干重），均符合GB18406.4-2001中汞的限量要求.背角无齿蚌对汞和甲基汞均有明显的富集，其组织对汞的积累也具有明显选择性（浓度高低依次为：外套膜 > 内脏 > 腮和肌肉）.背角无齿蚌中汞含量与水和沉积物中汞含量相关性良好，表明背角无齿蚌作为指示生物其生物监测结果可进一步验证水和沉积物中的汞污染水平.

Pollution characteristics and ecological risk of mercury in hangbu-fengle river of chaohu lake

Mercury contents in water, sediments and Anodonta woodiana were determined to study the pollution characteristics of mercury in Hangbu-Fengle River. Single Pollution Index and Index of Geoaccumulation were used to assess ecological risks. The results showed that the total mercury concentrations in water ranged from 0.04 to 0.20μg/L, with an average of 0.10μg/L. Total mercury contents in sediments ranged from 29.13 to 251.49μg/kg, with an average of 65.42μg/kg and methyl mercury contents ranged from 0.22 to 3.31μg/kg, with an average of 0.68μg/kg. Total mercury contents in sediments (H5, H9, F2, S4 and S5) were higher than the Ⅲ-level standard of the National Surface Water Environment Quality Standard. Mercury contents in sediments of the sites (H5, H9 and F2) were partial moderate pollution and another sites (S4, S5) were mild pollution, in which industrial emission was the main pollution sources. Total mercury contents in the mussels (Anodonta woodiana) ranged from 101.34 to 171.15μg/kg (dry weight), while methyl mercury contents ranged from 54.22 to 89.63μg/kg(dry weight), and they were all lower than the GB18406.4-2001. The accumulation of mercury and methyl mercury in the mussels was obvious and the accumulation of mercury in various tissues had obvious selectivity (mantle > guts > gill and muscle). According to the correlation analysis between the contents of mercury in water, sediments and mussels, Anodonta woodiana could be used as biomarker to further verify the mercury pollution level in water and sediments.