疏浚对湖泛的影响:以太湖八房港和闾江口水域为例

通过采集太湖八房港和闾江口疏浚后与未疏浚沉积物柱状样于室内模拟“湖泛”的发生与消退过程来研究底泥疏浚对藻源性“湖泛”形成和消退的影响.结果发现,疏浚能有效的延缓“湖泛”发生的时间,八房港和闾江口疏浚后沉积物柱状样水体色度均要低于未疏浚对照样,水体泛黑的时间也分别比未疏浚对照样延迟6d和2d.疏浚沉积物对上覆水柱中营养盐的含量也有较好的控制,试验过程中八房港和闾江口疏浚后沉积物柱状样水体中 NH4+-N的含量仅分别未疏浚对照组的40%和77.1%,PO43--P的含量也仅分别为未疏浚对照组的41.4%和78.1%.值得注意的是,疏浚沉积物所对应的水柱中Fe2+和S2-的含量均要高于未疏浚对照组.八房港和闾江口疏浚沉积物中亚铁的含量分别是未疏浚对照样的78.1%和76.4%,而闾江口疏浚后沉积物中酸挥发性硫化物(AVS)的含量则是未疏浚对照的1.36倍.沉积物中铁、AVS的含量没有表现出明显的垂向分布特征.

Effects of sludge dredging on black bloom: a case study of Bafang port and Lujiang port of Taihu Lake

In order to estimate the effects of dredging on the prevention and control of black bloom, four intact sediment cores had been sampled from dredged and un-dredged areas of Bafang port and Lujiang port to simulation the occurrence and regression of algae-caused black bloom with Y-shape apparatus. Results showed that dredging has a good effect on prevention the degree of algae-caused black bloom. The color of water in dredged treatment group was lighter than the control, and the occurrence time of black bloom in dredged sites of Bafang port and Lujiang port was delayed 6days and 2days, respectively. The concentrations of NH4+-N, PO43--P in overlying water of dredged treatment group of Bafang port and Lujiang port were only 40%, 77.1%, 41.4% and 78.1% of control treatment, and the concentrations of Fe2+ and S2- in overlying water of dredged treatment group were higher than control. The concentrations of Fe2+ in sediments of dredged sites of Bafang port and Lujiang port were 78.1% and 76.4% of control sites, and the concentration of Acid Volatile sulphide (AVS) in dredged site of Lujiang port was 1.36times than control. Vertical distribution characteristics of Fe2+ and AVS in sediment were not observed in this experiment. Overall, dredging can effectively prevent the occurrence of black bloom.