南四湖水体富营养化时空比较分析与评价

Spatial-time comparative analysis and evaluation of eutrophication level of Nansi Lake

南四湖是南水北调东线工程重要的输水通道和调蓄湖泊之一,随着通水时间的临近,其水质安全和水体富营养化状况备受关注.根据2006、2007、2010和2011年4次32个采样点的南四湖水质空间分布监测数据,采用综合营养状态指数法进行评价.结果表明,4个监测年枯水期南四湖水体总体平均处于富营养轻度水平,在南四湖水质得到大幅度改善的情况下,各年营养水平变化不大;南阳湖和独山湖水体的综合营养状态指数出现下降趋势,而昭阳湖(下)和微山湖岛北水体的综合营养状态指数出现上升趋势,这与全湖总磷出现均一化趋势有关.2010—2011年除微山湖岛南水体处于中营养水平外,其他湖区水体均处于富营养轻度水平.对南四湖水质空间分布监测数据的分析表明,南四湖藻类水华的繁殖生长主要受水体中TP的制约.

Abstract. Nansi Lake is one of the most important water deliver channels and storage lakes on the way of the East Route of the South-to-North Water Diversion Project. As the time of water delivering is approaching, a great attention shall be focused upon the problem of water quality security and eutrophication status of Nansi Lake. The data of 32 sampling sections in water quality spatial distribution of Nansi Lake has been monitored for four times in 2006, 2007, 2010 and 2011. The water eutrophication level in Nansi Lake was evaluated by Troph- ic Level Index method based on these data series. The results show that. the average eu- trophication level of Nansi Lake is light eutrophic during the four monitoring years. In the case of a significant improvement in the water quality of Nansi Lake, there is little change in the trophic level each year. The decreasing trend of Trophic Level Index appeared in Nan-yang Lake and Dushan Lake, but increasing trend was showed in Zhaoyang Lake （lower） and north of Weishan Lake. This is related to the homogenization trend that performed in TP in the whole Nansi Lake. In 2010-2011, except for the west of Weishan Lake whose water trophic level was moderate eutrophic, all the others were at light eutrophic level. The analy- sis of the monitoring data of Nansi Lake＇s water quality spatial distribution shows that the re- production of algal biomass in Nansi Lake is restricted by TP.