运用水质指数法评价厦门石兜—坂头水库水质

Assessment of Water Quality in Shidou-Bantou Reservoir by Water Quality Index Method

石兜—坂头水库是厦门市的重要饮用水水源地,其水质的好坏直接影响供水安全保障。根据2007年11月-2011年10月的水质监测数据,参照GB 3838-2002Ⅱ类水质标准,将27项水质监测指标分为3类,计算历年丰、平、枯水期水质综合指数(WQI),评价水质状况。结果表明:①难处理的毒性污染指标的WQI值小于10,远未危及水质安全;②易净化的污染指标中高锰酸盐指数、五日生化需氧量、大肠杆菌等在个别时段超标;③影响水质的最主要指标是总磷和总氮,单项指数常年保持在40以上,并曾一度接近80,达到Ⅳ类水质标准,水体受到一定的氮、磷污染。④4年来,水质变化处于相对比较稳定的状态,丰、平、枯水期水质变化不甚明显,最大WQI为33.3,水质评价为优良,是合格的供水水源地。就污染物成因及该水源地保护措施进行了探讨。

Shidou--Bantou reservoir is important a water source of Xiamen. Based on the data from November 2007 to Octo- ber 2011,27 water qualities parameters were grouped into three types to determine the water quality index（WQI） in abundant wa- ter periods, medium water periods or dry periods. The results show that ： 1 ： Single WQI of poisonous pollutants was less 10, far from endangering water quality security ; 2 ： IMn, BOD5 , colon bacillus in pollutants easy to purify sometimes went beyond the lev- el II of national standard for surface waters ; 2 ： Nitrogen and phosphorous were the most important parameters polluting water qual- ity, which single WQI were 〉 40 and once near to 80 ; 4. The highest WQI was 33.3 since 2007. The water quality was stable and good in different water periods. The reservoir was a qualified water source. Preliminary analysis on the source of pollutants and water quality conservation strategies were discussed.