基于底栖生物完整性指数的赣江流域河流健康评价

底栖生物完整性指数(B-IBI)是最为广泛应用的水生态系统健康评价指数之一。根据2009-2010年期间赣江流域60个采样点的底栖动物数据(15个参照点, 45个受损点), 对17个生物参数进行分布范围、判别能力和Pearson相关性分析, 确定了B-IBI指数体系由总分类单元数、甲壳和软体动物分类单元数、甲壳和软体动物%和BI指数构成。采用比值法统一各生物参数量纲, 将各个生物参数分值加和得到B-IBI指数值。根据参照点的B-IBI值的25%分位数值最终确定赣江流域河流健康评价标准。评价结果表明, 赣江流域60个采样点中19个为健康, 19个为亚健康, 14个为一般, 8个较差。综合来看, 赣江流域河流处于健康-亚健康状态: 上游各支流中绵水、贡江、上犹江和桃江为健康状态, 章水、濂水、梅江和平江为较差状态; 中游各支流健康评价结果多为健康-亚健康状态, 而乌江为较差状态; 下游各支流为健康-亚健康状态; 赣江干流上健康评价的结果均为健康。  

A HEALTH ASSESSMENT USING A BENTHIC-INDEX OF BIOTIC INTEGRITY IN GANJIANG RIVER BASIN

Benthic index of biotic integrity (B-IBI) is one of the most widely-used aquatic ecosystem health assessment indices. In the present study, benthic macroinvertebrates were sampled and collected from 60 stream sites in Ganjiang River basin during the period of 2009 to 2010, among which 15 sites were considered as reference sites and 45 impaired sites. Seventeen candidate metrics were selected for the establishment of B-IBI system, which were Shannon-Wiener index, Margalef index, Total number of taxa, (Crustacea+Mollusca) taxa, EPT taxa, Chironomidae taxa, Intolerant taxa, Dominant taxon %, Three dominant taxa %, Chironomidae %, Tubifex %, (Crustacea+Mollusca) %, Intolerant taxa %, Tolerant taxa %, Biotic Index, Predators % and Filterers %, respectively. The analyses of index value distribution, dis-crimination ability and Pearson correlation were then performed on these candidate metrics. After the analyses, four biological metrics, e.g. total number of taxa, (Crustacea+Mollusca) taxa, (Crustacea+Mollusca) % and Biotic Index were selected as the indicators of tolerance towards water pollution. B-IBI was obtained by summing up all these three indices after which were transformed into a uniform score by using the ratio scoring method. The criteria of health ranking were finally determined based on the 25% percentile of B-IBI value in reference sites. I-IBI values were assessed with these criteria, and results showed that among the 60 sites in Ganjiang River basin, 19 sites were health, 19 sub-health, 14 fair, 8 poor and no very poor. In the whole, rivers in Gangjiang River basin were in the state of health or sub-health. Tributaries were in health in its upstream such as Mianshui River, Gongjiang River, Shangyoujiang River and Taojiang River, while Zhangshui River, Lianshui River, Meijiang River and Pingjiang River were in the poor state; all most tributaries were in health or sub-health in the mid-stream except Wujiang River (poor); tributaries were also in health or sub-health in the downstream; main stream was in health through the river health assessment.