基于闸控管理的城市内河水体富营养化特征

Characteristics of eutrophication in gate-controlled urban river

分别于2013年夏季在江苏省南通市节制闸引水期、引水后与引水前采集不同级别城市河道水样,研究基于闸控管理的城市河网水体中TN、TP、Chl-a和CODMn的分布特征,并运用综合营养指数法对水体富营养化级别进行评价。结果表明,一级河道通吕运河引水后营养级别降低,引水对缓解通吕运河富营养化程度具有一定作用;二级河道通甲河富营养级别显著高于通吕运河(n=3,p=0.003),通甲河在引水期、引水后与引水前水体都属于重度富营养级别,由于同时受长江、通吕运河和海港引河等多水系来水影响,引水后,虽然综合营养指数有降低趋势,但所属营养级别没有改变;三级河道郭里头河营养级别显著高于通吕运河(n=3,p=0.02),但与通甲河没有显著差异(n=3,p=0.095),引水后,郭里头河营养级别降为中营养,主要是因为长江来水量大,水体交换率高;环城景观河濠河属于轻度富营养,在引水后综合营养指数达到最大,可能与其水系格局复杂有关。

Water samples were collected from urban rivers of different levels during , after, and before water diversion through a regulator from the Yangtze River to Nantong City , Jiangsu Province , in the summer of 2013 . The characteristics of distribution of TN , TP, Chl-a, and CODMn in a gate-controlled urban river network were analyzed , and the comprehensive nutrition index method was used to calculate the level of eutrophication .The results show that the trophic level of the first-class Tonglyu Canal declined after the water diversion , indicating that the eutrophication in the Tonglyu Canal can be reduced by water diversion .The trophic level of the second-class Tongjia River was significantly higher than that of the Tonglyu Canal （ n=3 , p=0.003 ） .The Tongjia River had a heavily eutrophic status during , after, and before the water diversion .Although the comprehensive nutrition index showed a declining trend after the water diversion , the trophic status of the Tongjia River did not change , as the river was affected by the incoming water from the Yangtze River , the Tonglyu Canal , and the Haigang River .The trophic level of the third-class Guolitou River was significantly higher than that of the Tonglyu Canal （ n=3 , p=0.02 ） , but showed no significant difference from that of the Tongjia River （ n=3 , p=0.095 ） .After the water diversion , the trophic level of the Guolitou River declined to a medium-eutrophic level , which might have been caused by the high inflow from the Yangtze River and high water exchange rate .The Haohe River , which is a landscape river surrounding the city , had a slightly eutrophic status .The comprehensive nutrition index of the Haohe River reached its maximum level after the water diversion , which might have been caused by the complex drainage pattern .