底泥疏浚生态环境效应的后评价研究——以山东省某河段整治为例

Study on ecological environmental effects of sediment dredging:A case study on river regulation in Shandong Province

对山东省某河段疏浚示范工程进行生态环境效应后评价,开展为期两年半的跟踪监测,主要分析底泥疏浚对河段水质、新生沉积物、底栖生物、微生物的长期影响.结果表明:底泥疏浚可有效降低水中的COD_(Cr)、TP含量,但对TN及NH^(+)_(4)-N含量的影响很小.疏浚区新生沉积物中的C/N值逐渐降低,这有利于微生物及底栖生物群落的恢复.疏浚可在一定程度上降低表层沉积物中颤蚓科的平均生物量及密度,而摇蚊科密度受疏浚影响较小.疏浚并未对河段沉积物微生物群落结构带来显著改变,这可能与疏浚深度有关.外源污染物的输入、人为排水作业等均可影响疏浚河段的水质及沉积物污染物含量,但当微生物群落基本构建完成后,这种影响可能在较短时间内恢复.综上所述,疏浚总体工程效果在研究开展期间(即疏浚后2~4年)有持续体现,即改善水质和沉积物污染状况,有利于底栖动物和微生物的多样性恢复.但随着时间的推移以及人为干扰的影响,水质维持效果有所下降.

In this study,follow-up monitoring over the course of two and a half years was carried out to analyze the long-term impact of sediment dredging on water quality,new sediments,benthos,and microorganisms of a river reach in Shandong Province.The results showed that the contents of COD_(Cr) and TP could be effectively removed by dredging,but little effect was observed on the contents of TN and NH^(+)_(4)-N.The C/N ratio in the new sediments decreased gradually over the observation period,which was beneficial to the recovery of microbial and benthic communities.Dredging can reduce the average biomass and density of tremididae in surface sediments to a certain extent,while Chironomidae density is less affected by dredging.Dredging did not change the microbial community structure significantly,which may be related to the depth of dredging.Exogenous pollutants and man-made drainage can affect the water quality and sediment pollutant content of the dredged river section;this effect,however,may recover in a short time after completion of the microbial community construction.In conclusion,the overall engineering effects of dredging were observed during the study period(2–4 years after dredging);in this time,the water quality and sediment pollution improved,which was conducive to the restoration of benthos and microbial diversity.However,with the passage of time and human interference,the net effect on water quality maintenance weakened.