疏浚对梅粱湾表层沉积物重金属赋存形态及其生物毒性的影响

选择太湖梅梁湾未疏浚、疏浚后1周和疏浚后半年的表层沉积物为研究对象，测定其中重金属的含量及其不同赋存形态所占比例，开展沉积物间隙水中重金属毒性试验，据此探讨疏浚对沉积物中重金属含量及其赋存形态所占比例和生物毒性的影响. 结果表明:太湖梅梁湾调查区未疏浚沉积物重金属含量明显高于疏浚区，重金属的生物毒性占沉积物综合毒性的25%～35%. 疏浚后1周沉积物重金属含量急剧降低32%～51%，但对重金属生物毒性影响较大的吸附态及碳酸盐结合态重金属比例由未疏浚时的未检出或含量极低增加到40%～83%，生物毒性相应增加17%～38%；疏浚后半年，沉积物中重金属的总量略有回升，吸附态及碳酸盐结合态重金属比例下降，生物毒性下降并低于未疏浚时水平. 

Effects of Dredging on Speciation and Bio Toxicity of Heavy Metals in the Surface Sediment from Meiliang Bay, Taihu Lake

The surface sediments from three different regions （un-dredged, dredged for one week and dredged for half a year） from Meiliang Bay, north of Taihu Lake were collected to determine the contents and the proportion of various species of heavy metals, to perform toxicity tests of heavy metals in the pore water of the sediments, and to investigate the impacts of dredging on the contents. The concentrations of heavy metals from un-dredged sediment were obviously higher than those from dredged sediment, and their bio-toxicity accounted for 25%-35% of the comprehensive toxicities. The concentrations of heavy metals from sediment dredged for one week were reduced by as much as 32%-51%; however, the proportion of absorbed and carbonate-bound heavy metals, which have a significant impact on the bio-toxicity of heavy metals, increased from below the detection limit or extremely low concentration in the un-dredged sediment to 40%-83% in the sediment dredged for one week, and the bio-toxicities also increased 17%-38% accordingly. The concentrations of heavy metals in the sediment dredged for half a year had a slight rebound; the proportion of absorbed and carbonate-bound heavy metals decreased, and the bio-toxicities declined to a level lower than those in the un-dredged sediment.