武汉东湖富营养化的综合评价

COMPREHENSIVE EVALUATION OF EUTROPHICATION IN DONGHU, LAKE WUHAN

兼顾富营养化评价和水生态系统常规监测,提出了以7种常见营养物(NO_3-N,NO_2-N,NH_4-N,TN,PO_4-P,TP,SiO_2)和浮游植物3个常用参数(日平均初级生产量P_G,生物量B,chla)为指标体系的湖泊营养类型评价标准;使用层次分析法,对上述10个因子作出权重分配,从而建立起评价湖泊富营养化程度的一种新方法。评价结果表明:尽管近年来东湖浮游植物的几项指标有所下降,但东湖富营养化程度奉有明显改变,

Evaluation of the eutrophication in a (or trophic state of) lake is a multivariate comprehensive decision-making process quantifying the qualitative probltm. Besides establishment of a rational evoluation index system for the trophic state of a lake, a key problem in this process is to determine the weight attributions of the observed indices. Wing indices commonly used to the monitor aquatic ecosystem, this work included seven nutrient (nitrate-N, nitrite-N, ammonium-N, total-N, phosphate-P, total-P and silicates) and three phytoplanktonic (mean gross primary productivity, biomass and chorolophyll a) parameters in the index system. By using hierarchial analysis, the weight contributions of the ten parameters to eutrophication were determined in % as 2.9, 0.7, 1.7, 8.3, 5.3, 13.2, 1.3 and 16.6, 10.5, 39.6 respectively for nitrate-N, nitrite-N, ammonium-N, total-N, phosphate-P, total-P, silicates and mean gross primary productivity, bio-mass, chorolophyll a (consistency ratio CR = 0.06<0.10). This work established new method for evaluating lake eutrophication was established. The application of this evaluation system to Donghu, Lake Wuhan, demonstrated that the eutrophication in this lake was quite serious. Data from 1980 to 1984 at the two sampling stations in the lake showed that this lake was changing from an eutrophic to a hypereutrophic one. It is pointed out that the trophic state of Donghu Lake did not undergo significant changes in recent years, although values of several parameters, especially phytoplanktonic indices, obviously declined. The ecological application of the analytic hierarchy process is discussed in this paper.