富营养化评价方法在宁夏清水河流域的适用性研究

Applicability Research of Eutrophication Evaluation in the Qingshui River Basin of Ningxia

为探明清水河流域富营养化状态,于2018年4月、7月和11月对其32个采样点的水环境因子进行采样测定,选取叶绿素a(Chl.a)、总氮(TN)、总磷(TP)、高锰酸盐指数(COD_(Mn))、透明度(SD)作为评价因子,应用生物多样性指数法、综合营养状态指数法和灰关联法对清水河流域富营养化状态进行评价。结果表明:Shannon-Wiener多样性指数评价清水河干流富营养化状态为中至富营养化,Margalef物种丰富度指数评价干流为富营养化;综合营养状态指数法评价清水河流域富营养化状态为中营养化,上游、中游、苋麻河、西河、井沟、折死沟均为轻度营养化,其余均为中营养状态;灰关联法评价清水河流域富营养化状态为中营养化状态。不同来水期,富营养化状态变化明显,在时间上,4月、11月为中营养化,7月为轻度富营养化;在空间上,折死沟为轻度富营养化,双井子沟接近轻度富营养化,其余点位为中营养化。结合清水河流域实际情况,对比生物多样性指数法、综合营养状态指数法,使用灰关联法对清水河流域进行富营养化评价结果更加客观、可靠。

In order to find out the eutrophication status of the Qingshui River basin,this paper measured the water environmental factors of its 32 sampling points in April,July,and November of 2018,and selected Chl.a,TN,TP,COD_(Mn) and SD as evaluation factors.In addition,the paper applied biodiversity index method,comprehensive nutrition state index method and gray correlation method to evaluate the eutrophication status.The results show that the eutrophication status of its main stream are medium to eutrophic and eutrophic by Shannon-Wiener diversity index and Margalef species richness index respectively;the status is evaluated as mesotrophic by the comprehensive trophic state index method,besides,the upper reaches,middle reaches,Rama River,Xihe River,Jinggou and Zhesigou are all evaluated as mildly trophic while the rest are middle nutritional;Furthermore,the status is evaluated as mesotrophic status by grey correlation method.The eutrophication status have changed significantly in different inflow periods.In terms of time,the status is mesotrophic in April and November while mild eutrophic in July.In terms of space,the status is mild eutrophic in Zhesigou while is close to mild eutrophic in Shuangjingzigou,and the remaining sites are mesotrophic.Based on the above evaluation,the gray correlation method is more reliable to evaluate the eutrophication of Qing Shui River basin.