采用主成分分析法评价廉州湾贝类养殖区水质状况

摘要

To understand the water quality of shellfish culture areas in Lianzhou Bay of Guangxi Province and better guide local fishery production,eight water quality factors of the areas were analyzed with SPSS,namely the water temperature,DO,COD,DIP,DIN,oil,Hg and Chl-a,and principle component analysis method was adopted to determine the major influencing factors and comprehensively evaluate the water quality. The results showed that,during the spawn period ( May) and high catch period ( October) ,the first four main components, together accounting for 89. 9% and 92. 9% respectively of the total variance of the two periods, could be extracted to calculate the comprehensive evaluation function score, and the scores of each measuring period from 2013 to 2015 were respectively 0.220,-0.211,0.759,1.028,-0.977,and -0.817,with the score levels representing the pollution degree:water quality of both the spawn period and high catch period of 2013 belonged to class III,that of the two periods of 2014 belonged to class IV,and that of 2015 belonged to class I in spawn period and class II in high catch period.It can thus be seen that the water quality of shellfish culture areas was not stable,with relatively large interannual variations,Hg exceeding standard occasionally,and DIP, DIN and Chl-a being the major polluting factors. Therefore,the culture areas should enhance the management over daily operations and industrial outfalls,better control the discharge of sewage and agricultural waste water, as well as scientifically plan the farming scale in order to prevent shellfish farming pollution.%为了解广西廉州湾贝类养殖区水质状况并指导渔业生产,借助SPSS软件,分析了2013—2015年该养殖区的水温、溶氧(DO)、化学耗氧量(COD)、溶解态无机磷(DIP)、溶解态无机氮(DIN)、石油类、汞(Hg)和叶绿素-a(Chl-a)等8项水质因子.采用主成分分析法筛选对养殖区影响较显著的因子来综合评价水质状况.结果显示,在产卵期(5月)和高渔获期(10月)可以各提取占总方差89.9%、92.9%的前4个主成分来计算综合评价函数得分,2013—2015年各监测期水质综合得分依次是0.220、-0.211、0.759、1.028、-0.977、-0.817,分值高低反映水质污染程度.2013年两个监测期的水质均属于III类,2014年两个监测期的水质均属于IV类,2015年产卵期水质属于I类,2015年高渔获期水质属于II类.由此可知,养殖区水质综合状况不稳定,年际间变化较大,曾出现Hg超标情况,污染较严重的是DIP、DIN和Chl-a.因此,养殖区应加强码头日常作业及沿岸工业排污口管理,同时应控制生活污水、农业废水排入,合理规划养殖规模,防止贝类养殖自身污染.