滤食性动物放流对西五里湖的生态修复作用初探

根据生物操纵原理，以TP、TN、NO3--N、NO2--N、NH4+-N、CODMn、Chla、SD等为主要水质指标，采用综合营养状态指数法，研究了滤食性生物螺（C. cathayensis）、蚌（Hyriopsis cumingii）、鲢（Hypophthalmichthys molitrix）、鳙（Aristichys nobilis）放流对西五里湖湖区生态环境的修复作用。结果表明：放流后，西五里湖水体透明度有显著升高趋势，平均提高了26.8%，其中最大值达60cm，比放流前提高了91.7%；TP含量呈下降趋势，8次监测中有6次的测定值符合《地表水环境质量标准》（GB3838-2002）的Ⅱ类水质要求，占总监测次数的75%；虽然8次监测中的TN含量均属劣Ⅴ类，但其含量与放流前相比有降低趋势；同时，综合营养状态指数也从放流前西五里湖高于东五里湖，转变成放流后东五里湖高于西五里湖。说明向富营养化湖泊放流滤食性生物对提高水体透明度、降氮、除磷具有良好效果，能够使水质富营养化程度得以减轻。

Preliminary study on eco-restoration effect of releasing suspension-feeding animal on west Wuli lake

Samples were collected once a month from March 27th to November 6th (8 times aggregately) from the water of west Wuli lake, released with suspension-feeding animal such as spiral shell (C. Cathayensis), mussel (Hyriopsis cumingii), silver carp (Hypophthalmichthys molitrix) and bighead carp (Aristichys nobilis), a mode of eco-restoration method, and the water in east Wuli lake were sampled at the same time, as the control. Total phosphorus (TP), total nitrogen (TN), nitrate nitrogen (NO3--N), nitrite nitrogen (NO2--N), ammonium nitrogen (NI4+-N), CODMn and chlorophyll-a (Chla) in the samples were analyzed at laboratory and pH value, transparency (SD) and dissolved oxygen (DO) of water in the sampling locations were also monitored at the time of sampling, witch were used as main quality indexes for evaluation of effect of the eco-restoration method on purifying eutrophication water. Results showed that in the eight times of monitoring after releasing suspension-feeding animal in west Wuli lake, transparencies in west Wuli lake taken on a trend of increasing, and the mean value improved by 26.8%, with the biggest value of 60 cm improved by 91.7%, compared with that of the background. Concentrations of total phosphorus in west Wuli Lake decreased and the total phosphorus achieved the Ⅱ classification of environmental quality standard for surface water (GB 3838-2002)at the time of March, April, May, June, July and November, accounting for 75% of the total monitoring times. Although total nitrogen belonged to the below Ⅴ classification of environmental quality standard for surface water (GB3838-2002), it decreased compared with that of the background. The comprehensive trophic state indexes (TLI0) changed from the west Wuli lake being higher than the east Wuli lake before releasing suspension-feeding animal to the east Wuli lake being higher than the west Wuli lake after releasing suspension-feeding animal. So, releasing spiral shell, mussel, silver carp and bighead carp in eutrophic lake could improve transparency, reduce nitrogen, remove phosphorus effectively and make the degree of eutrophication decrease finally.