孤东水库水体富营养化评价及其生态控制研究

Evaluation and Ecological Control of the Eutrophic State of Gudong Reservoir

对孤东水库水生物状况进行系统调查和水体富营养状态进行评价,在此基础上,提出了生态修复技术,通过理论计算与试验确定草食性和滤食性鱼类的投放量,并进行了围格试验.结果表明,孤东水库菹草优势度达80%,浮游植物量为22.32mg/L,单位面积上的总磷浓度是0.310 g/(m2.a),水体处于富营养化状态.通过保持孤东水库鲢、鳙鱼的水体生物量在19～25 g/m3左右,在9月藻类繁殖高峰期,生物量由14.6 mg/L降为3 mg/L.总磷、总氮和高锰酸盐指数年均值分别由生态控制前的0.06 mg/L、3.06 mg/L和4.42 mg/L降为0.03 mg/L、1.58 mg/L和3.73 mg/L,水库水质改善效果明显.同时下游水厂的单方水药耗也由生态控制前的42 g/m3降至25 g/m3.试验证明,通过采用合理投放草食性和滤食性鱼类的生态修复技术,可以有效控制水库富营养化状态,并取得显著的社会、经济效益.

The eutrophic state of Gudong reservoir and relative factors were investigated and evaluated.Then a comprehensive ecological control technology was proposed.The amount of herbivorous fish and filter-feeding fish was determined both through theoretic calculation and experimental test.The results demonstrated that Potamogeton crispus was the dominant grass over 80%,the phytoplankton biomass was 22.32 mg /L,and the total phosphors was 0.310 g /（m2.a）,which suggested that Gudong reservoir was on the eutrophic state.Through ecological engineering by controlling the biomass of Hypophthalmichthys molitrix and Aristichthys nobilis at 19-25 g /m3,the algae biomass was reduced from 14.6mg /L to 3mg /L at September,the annual average total phosphorous,nitrogen and permanganate index were reduced from 0.06 mg /L,3.06 mg /L and 4.42 mg /L to 0.03 mg /L,1.58 mg /L and 3.73 mg /L,respectively,which showed that the reservoir water quality has been obviously improved.Also,the flocculant dosage to treat this reservoir water was reduced from 42 g /m3 to 25 g /m3 after ecologic control.The results showed that the eutrophication could be controlled effectively by adopting the ecological restoration technology with rationally introducing the herbivorous fish and filter-feeding fish,and significant benefits can also be achieved.