摘要
以详细的水质监测资料为基础,采用标准指数法并结合实地调查,分析了1990～2003年洪湖水质的变化状况.结果表明,14 a间,洪湖水质类别以Ⅲ类和Ⅳ类为主.水质恶化的驱动因子是氮、磷及其它有机污染物.1991年到1994年期间,水体中氨氮（NH4^＋-N）占溶解无机氮（DIN）的比例逐年增高;1995～2003年,以氨氮和硝酸盐（NO3^--N）同时作为水体中溶解无机氮的主要存在形式,与1990～1994年的水质状况相比,亚硝酸盐（NO2^--N）所占的比例呈增加之势.氨氮、硝酸盐和亚硝酸盐的年际变化表明,洪湖水体自净能力在逐渐降低.以总磷（Tp）、总氮（TN）和溶解无机氮（DIN）作为评价指标,洪湖水体已属中富营养型湖泊.洪湖水质演变与该区域人类活动（围湖造田、围网养殖等）以及江湖连通的变化对水环境的作用相耦合.
Honghu Lake, crossing over Honghu county and Jianli county in the southeast of Hubei province, is situated in the north of the middle reaches of Yangtze River. As a low - lying lake between Yangtze River and a branch of Han River and Dongjin River, it is the end of Four - Lake water system in the Jianghan Plain. The catchments basin of Honghu Lake covers about 5 025km^2. And there is 344 km^2 area of water body now. The average water depth of the Lake is 1.34 m. The maximum is 2.30 m and the minimum is 0.40 m. Honghu Lake is a big shallow lake and the seventh freshwater lake in China. It has many functions such as water supply, irrigation, habitat of wetland creatures, freshwater aquiculture, shipping, tourism and so on. Honghu Lake is a representative lake in the Jianghan Plain as well as in the middle and lower reaches of Yangtze River.
Because of unreasonable exploitation of wetland resources, Honghu Lake is confronted with series lems such as decrease of the lake area, shrinkage of the lakeside zone, decrease of wetland biodiversity, probsharp reduction of rare species and the eutrophication of water body. These problems have restricted the sustainable development of local economy severely, and aroused more attention of government. It is significant to protect water environment of Honghu Lake. So study of water environment quality will provide a scientific basis for the sustainable development of Honghu Lake.
According to the detailed information of investigation, including the data of temperature, pH, suspended solid, dissolved oxygen （DO） , permanganate index （ CODMn ） , 5 - day chemical oxygen demand （ COD5 ） , 5 - day biochemical oxygen demand（BOD5）, NH4^ ＋- N, NO2^ --N, NO3^ --N, volatilizing phenols, cyanide, arsenic, chromes（ Cr6 ^＋ ） , lead, cadmium （ Cd2^＋ ）, electrical conductivity, total nitrogen （TN） , total phos- phorus （TP）. The water quality was analyzed over past 14 years （ 1990 to 2003 ） in Honghu Lake. The resuits indicated that the classification of the water quality belonged to Grade Ⅲ and Grade Ⅳ generally from 1990 to 2003 according to the National Surface - water Standard （ GB3838 - 2002 ）. The average annual value above Grade Ⅱ standard included CODMn, COD5, BOD5, NH4^ ＋- N, TN and TP. All other indexes conformed to a Grade I or Grade Ⅱ Standard for Surface - water quality. The driving factors causing the deterioration of water quality were N, P and other organic pollutants. The annual change of three kinds of dissol uble inorganic nitrogen （DIN） indicated that the percentage of NH4 ^＋- N in DIN increased gradually from1991 to 1994. And in the following nine years, the NH4 ^＋-N and organic nitrogen in water. The content of NO2^ -- N was very few, implied that the selfcleaning ability of water body had been which also illustrated that the organic pollution was accelerating. NO3^ -- N were main forms of dissoluble inbut it increased in DIN receding. The index of year by year. This CODMn increased, which also illustrated that the organic pollution was accelerating.
From the ratio of N/P, it was concluded that the P restricted the growth of plankton community. Honghu Lake has become a medium -eutrophicated lake according to indexes of TP, TN and DIN. Under the conditions of higher N/P ratio and abundant N content, a little amount of P in the water could lead to a rapid increase of alga. Therefore, controlling the content of phosphorus to enter into the lake and the bottom mud to release phosphorus become the key for protecting water environment of Honghu Lake. The intensive producing and human activities around the lake made the grass use up and the lakeside zone decrease sharply. The relation between the change of ecologic structure in Honghu Lake and its water quality development was coupling.
In order to make the Honghu Lake more available for people＇s production and daily life, we should take some effective steps to reconstruct the environment structure - strengthening the means to reduce inland and enlarge lake, controlling the space of cultivation, restoring the lakeside zone and constructing effective program, which will connect lakes and rivers.
出处
《湿地科学》
CSCD
2006年第2期115-120,共6页
Wetland Science
基金
湖北省涝渍灾害与湿地农业重点实验室开放基金(HNKFJ2002B03)资助
关键词
洪湖
水环境
富营养化
Honghu Lake
water environment
entrophication
