Application of water quality identification index to environmental quality assessment of Nansi Lake | 水质标识法在南四湖水质评价中的应用

Chinese. 根据2005-2011年南四湖5、8月份的实测结果，应用水质标识指数法对南四湖水环境状况分别进行单因子评价和综合评价。结果表明：2005～2011年期间，南四湖综合水质标识指数平均值分别为4.431，3.980，3.630，3.470，4.081，3.570，4.081，水质处于Ⅲ-Ⅳ类水，总体有所改善，但距离稳定达到IH类水质标准仍有差距；主要污染因子总氮（TN）、总磷（TP）、化学需氧量（CODMn），相应的单因子水质标识指数平均范围为3.58-6.88、2.23-8.42、3.47-4.73，叶绿素（Chla）标识指数平均范围为3.24-5.03，溶解氧（DO）和氨氮（NH3-N）标识指数平均范围为1.00-2.95、1.00-3.69，基本能达到指标要求。7年期间，各站点综合水质标识指数呈现5月份低、8月份高的规律性变化趋势。本文通过水质标识法对南四湖水质环境进行综合评价，为改善及修复南四湖水质提供支持。

English. This study was carried out to evaluate the water quality of Nansi Lake with the method of single factor and comprehensive water quality identification index, based on the data collected from six sampling sites from May 2005 to August 2011. The results indicated that the average comprehensive water quality identification index of Nansi Lake in seven years was 4.431, 3. 980, 3.630, 3.470, 4.081, 3.570, 4.081, respectively; the comprehensive water quality grade of Nansi Lake was between Ⅲ- Ⅳ, which has been improved, but not stable to water quality Ⅲ standard. The lake was mainly polluted by total nitrogen (TN), total phosphorus (TP), chemical oxygen demand (CODMn), and the corresponding single factor water quality identification index average range were 3.58 - 6.88, 2.23 - 8.42 and 3.47 - 4.73. The water quality identification index average range of the Chla was 3.24 - 5.03. The range of dissolved oxygen (DO) and ammonia-nitrogen (NH3-N) were 1.00 - 2.95 and 1.00 - 3.69, which could meet the standard of functional objectives of water. During the seven years, the comprehensive water quality identification index showed seasonal fluctuations, which was low in May, but high in August. The present study carried, out evaluating on Nansi Lake by water quality identification index, which provided support for the improvement and rehabilitation of Nansi Lake water quality.