基于综合营养状态指数法的石佛寺水库水质富营养化评价

Eutrophication of Shifosi Reservoir Based on Comprehensive Nutrition State Index

为了评价石佛寺水库水质的富营养化状态,采集2012-2015年石佛寺水库的水质监测数据,利用综合营养状态指数法对水库入库口、库中和出库口综合营养化指数进行计算,并对水库水质的营养状态进行评价和分析.分析结果表明：石佛寺水库2012-2015 年水质各月份营养级别都处于轻度富营养化或中度富营养化,营养状态指数从中度下降至轻度,中度富营养化月份占全年比例由75%下降到37.5%,综合营养状态指数由2012 年的62.06%下降到2015 年的57.76%.由总氮（TN）、总磷（TP）、高锰酸盐指数（CODMn）、叶绿素a（Chla）和透明度（SD）5 项参数的综合营养状态指数的评价结果表明：总氮指标最高,可以断定总氮是引起石佛寺水库水质下降的主要原因.石佛寺水库2012-2015 年部分月份水质劣于《地表水环境质量标准》芋类水质标准,有些月份甚至只能达到郁类水质标准.通过对水环境因子之间的相关分析结果表明：pH与溶解氧（DO）呈极显著正相关,透明度与溶解氧呈极显著负相关,总氮与溶解氧呈极显著正相关,总磷与pH呈极显著负相关,总磷与总氮呈显著正相关,叶绿素a 与总氮、总磷都呈显著正相关关系,高锰酸盐指数与总磷呈极显著负相关.本研究的石佛寺水库水质的评价方法和结果可为该区域内的水质富营养化控制和改善提供实践指导.

Based on the monitoring data of water quality at Shifosi Reservoir in 2012-2015, the eutrophic state was evaluated and analyzed by using comprehensive trophic status index. Analysis results showed that the water of Shifosi Reservoir in the mild or moderate level of eutrophication from 2012 to 2015. The trophic status index decreased from moderate to mild. The percentage of moderate eutrophication decreased from 75% to 37.5%. The comprehensive trophic status index decreased from 62.06% in 2012 to 57.76% in 2015. The influence of various parameters(including TN, TP, CODMn, Chla and SD5) on the comprehensive trophic status index was evaluated. The results showed that the index of TN was the highest and was the main reason for the declining of water quality. The water quality was under the Ⅲ class of environmental quality standards in 2012-2015, even under the Ⅳ class in some months. By the correlation analysis among the water environmental factors, the results showed that pH positively correlated with the DO; SD negatively correlated with DO; TN positively correlated with DO; TP negativey correlation with pH; TP and TN were positivly correlated; Chla positively correlated with TN and TP; CODMn negatively correlated with TP. Our methods and results of water quality evaluation in the region provided a practice guidance for controlling and improving the water eutrophication.