崇明岛河道水质指标季节性变化分析

采用主成分分析法和SPSS统计软件,对2007年从崇明岛河道12个水质监测点监测所得枯水期与丰水期的18个水质指标数据进行处理,从原始监测数据提取出占总方差85%以上的5个主成分,并计算其贡献率和12个监测点的主成分值。分析表明:枯水期,硫酸、磷酸、钾在第1主成分载荷较高,镁在第2主成分载荷较高,铁、色度、硫在第3主成分载荷较高;丰水期,钾在第1主成分载荷较高,镁、铜在第2主成分载荷较高,亚硫酸、亚硝酸在第3主成分载荷较高。据此得出结论:崇明岛水质受农业和海水倒灌的影响较大,工业对河道的影响较小。认为,应减少崇明岛农药化肥的使用,推广滴灌灌溉,防止过多的灌溉用水携化肥等流入河道;枯水期可采用人工向河道注水的方式防止海水倒灌,丰水期可依旧采取现有南进北出的方法引入长江淡水;减少崇明岛内工业企业,降低工业污染对河道的影响,并对不能搬离企业的生产过程进行严格监管,严禁工业废水未经处理直接向岛内河道排放。

Analysis of seasonal changes in water quality of Chongming Island in Shanghai, China

Eighteen water quality indexes at 12 water quality monitoring points on Chongming Island, Shanghai, China, in the low-flow period and high-flow period of 2007 were analyzed with the principal component analysis method and SPSS software, The five principal components with a total variance of over 85 % were extracted and their contributions and values were also calculated. The results from the analysis indicated that, in the low-flow period, there are high loads of sulphate, phosphate and potassium in the first principal component; a high load of magnesium in the second principal component; and high loads of iron, color and sulphide in the third principal component. In the high-flow period, there is a high load of potassium in the first principal component, high loads of magnesium and copper in the second principal component, and high loads of sulphite and nitrite in the third principal component. It can be concluded that the water quality of Chongming Island was affected primarily by agricultural activities and sea water encroachment and secondarily by industry. The following measures are necessary： reduction of the utilization of pesticide and fertilizer, popularization of sprinkler and drip irrigation, and reduction of discharge of irrigation water with a high fertilizer concentration into rivers. Artificially diverting water into the river can prevent sea water encroachment during the low-flow period. The measure of diverting fresh water from the Yangtze River in the south and discharging into the Yangtze River in the noah can also be used to improve the water quality in the high-flow period. The number of industrial enterprises must be reduced in order to reduce the influence of industrial pollution of rivers. The operation of those enterprises that cannot be moved away from Chongming Island should be under strict supervision, and industrial wastewater discharge into rivers without any treatment should be prohibited.