黄浦江江水和沉积物中汞的分布和形态特征

黄浦江江水的总汞、溶解态汞和颗粒汞含量变化较大,其平均值分别为(0.4±0.44)ng/mL、(0.27±0.42)ng/mL和(0.13±0.10)ng/mL,江水中汞以溶解态汞为主.黄浦江沉积物的总汞含量为70.52ng/g～387.30ng/g,平均汞含量为(204.03±97.41)ng/g.江水和沉积物中汞的沿江分布具有中游高,上游和下游低的特征,西渡—南浦大桥江段汞含量为整个黄浦江最高的江段,汞的分布特征与两岸工农业布局相一致.沉积物总汞与有机质显著相关,沉积物中高汞含量的地点都在高水汞点的下游,与河流的动力沉积特点一致.沉积物中汞以可交换态、腐殖酸结合态、残渣态为主,少量为碳酸盐结合态.从上游到下游,沉积物中可交换态汞具有两端高中间低的特点,而残渣态汞与此相反.在剖面方向上,沉积物中的汞主要集中在残渣态,少量为腐殖酸结合态,可交换态及碳酸盐结合态,随着深度增加残渣态所占比例不规则增加.愈接近长江口,沉积物中的重金属愈容易被重新激活.

Distribution and species of mercury in water and sediments from Huangpu River

Levels of total mercury, soluble mercury and particle mercury in water of Huangpu River change greatly, their average values are (0.40.44)ng/mL, (0.270.42)ng/mL, (0.130.10)ng/mL respectively. Mercury in water is mainly in the form of soluble mercury. Average mercury content in sediment of Huangpu River is relative high and up to (204.0397.41)ng/g, with a range of 70.52ng/g387.30ng/g. Mercury content is high in the middle reach of Huangpu River, especially in section of Xidu-Nanpu Bridge, and low in upstream and downstream. Distribution of mercury is hightly related with distribution of industry plants and farming. Locations with high mercury content in sediment are in the downstream of locations with high mercury content in water. Mercury (in sediments) is mainly in the form of residue, exchangeable ions, and humics-bound, seldom is in the form of carbonate-bound. Contrary to residue-bound mercury, exchangeable mercury is low in the middle reach, and high in upstream and downstream. There mainly are residue-bound mercury and little humics-bound mercury, exchangeable mercury, and carbonate-bound mercury in sediment in profile, and the residue-bound mercury increases irregularly with depth. Nearing the Mouth of Yangtze River, mercury in sediment becomes more active.