城市河道环保疏浚与水利疏浚效果研究——以无锡市梁塘河薛家浜为例

以内源污染严重的无锡市梁塘河薛家浜为研究区,开展环保疏浚和水利疏浚试验,通过疏浚前后底泥和水体中总氮、总磷浓度变化及底泥中氮、磷的静态释放通量,评估2种疏浚方式对河道内源污染削减效果的影响。结果表明:2种疏浚方式都能有效降低底泥中营养盐浓度,环保疏浚后底泥中总氮、总磷浓度分别削减了46.50%和35.51%,水利疏浚后分别削减了40.10%和30.51%。但达到同样疏浚效果时,相较环保疏浚,水利疏浚的工程量增加;在外源污染得到较好控制的前提下,2种疏浚方式均能有效削减内源释放对水体的污染,其中环保疏浚对氮、磷释放通量削减率较高,分别为46.92%和38.53%,水利疏浚则为40.99%和30.09%;考虑到城区土地资源紧缺,水利疏浚易超挖及疏浚后水生态系统较难恢复的问题,建议采取环保疏浚方式解决城市河道内源污染问题。

Study on the effect of urban river environmental dredging and hydraulic dredging:taking Xuejiabang,Liangtang River of Wuxi as an example

In view of the serious endogenous pollution in Xuejiabang, Liangtang River of Wuxi City, two dredging methods, including environmental dredging and hydraulic dredging, were applied to evaluate the effect of dredging on the reduction of endogenous pollution in river by studying the changes of total nitrogen and total phosphorus in sediment and water before and after dredging, and the static release flux from the sediment. The results showed that the two dredging methods could effectively reduce the nutrient contents in the sediment. After environmental dredging, the total nitrogen and total phosphorus concentrations were reduced by 46.50% and 35.51%, respectively, and after hydraulic dredging, the total nitrogen and total phosphorus concentrations were reduced by 40.10% and 30.51%, respectively. But to achieve the same dredging effect, hydraulic dredging would lead to an increase in the amount of work compared with environmental dredging. On the premise of better control of exogenous pollution, both the two dredging methods could effectively reduce the pollution caused by endogenous release to water. The nitrogen and phosphorus release flux reduction rate of environmental dredging was higher with 46.92% and 38.53%, respectively, while that of hydralic dredging was 40.99% and 30.09%, respectively. In view of the shortage of land resources in urban areas, the problem of easy over-digging by hydraulic dredging and the difficulty in recovering the water ecosystem after dredging, it was suggested to adopt the environmental dredging method to solve the problem of the internal pollution of urban river courses.