基于大型底栖动物完整性指数的新疆额尔齐斯河健康评价

为建立我国西北地区跨境河流生态系统健康的评价指标与标准,应用B-IBI (benthic-index of biotic integrity,底栖动物完整性指数)评价新疆额尔齐斯河流域的健康状况. 于2012年7月、8月、10月及2013年5月在额尔齐斯河全流域设10个典型采样点,进行4次大型底栖动物调查,从23个候选生物指标中筛选出适用于构建额尔齐斯河B-IBI评价体系的参数,主要包括总分类单元数、EPT(蜉蝣目、襀翅目、毛翅目)分类单元数、前3位优势分类单元个体相对丰度、襀翅目个体相对丰度和黏附者个体相对丰度. 以参照点B-IBI的25%分位数作为健康评价标准来确定B-IBI的评价等级:B-IBI>2.04为极好,1.53＜B-IBI≤2.04为好,1.02＜B-IBI≤1.53为一般,0.51＜B-IBI≤1.02为差,B-IBI≤0.51为极差. 结果表明:在所有采样点中,6个采样点处于健康状况极好或好的状态,3个采样点健康状况一般,1个采样点健康状况较差；各采样点B-IBI在不同月份变化各异. 整体来看,额尔齐斯河的水体健康状况较好,但局部河段水体受到不同程度污染. 基于B-IBI的健康评价结果与其他生物指数〔Chandler计分制生物指数、BMWP(biological monitoring working party)分数系统分值〕评价结果相一致,表明所构建的B-IBI评价指标与标准对额尔齐斯河的健康状况评估具有较好的适用性,可作为额尔齐斯河流域水体环境监测的一种有效手段. 

Health Assessment of Irtysh River in Xinjiang Uygur Autonomous Region, Northwest China, based on Benthic-Index of Biotic Integrity (B-IBI)

The Benthic-Index of Biotic Integrity (B-IBI) was applied to evaluate the health state of Irtysh River drainage in Xinjiang Uygur Autonomous Region, in order to build an assessment criteria and standard of ecosystem health for cross-border rivers in northwestern China. Twenty-three candidate metrics of benthic macroinvertebrates were selected from 10 typical sampling sites from Irtysh River sampled in July, August, October 2012 and May 2013. Then, five key metrics were detected and entered into the final B-IBI system, including the number of the total taxa, the number of EPT (Ephemeroptera, Plecoptera, Trichoptera), the three-dominant taxa percentage, the Plecoptera percentage and the clingers' percentage. Based on 25% percentile of B-IBI value in reference sampling sites, the assessment grades were as follows:B-IBI>2.04 represents excellent, 1.53＜B-IBI≤2.04 represents good, 1.02＜B-IBI≤1.53 represents fair, 0.51＜B-IBI≤1.02 represents poor and B-IBI≤0.51 represents very poor. Finally, according to the assessment criteria, it was determined that six reaches of Irtysh River were excellent or good, three were fair and one was very poor, and the ecological status varied seasonally. Overall, the water quality of Irtysh River belonged to a better state except for partial reaches of the river, which suffered from human disturbances. Moreover, the assessment results based on the B-IBI were consistent with those from other biotic indexes (Chandler, BMWP (biological monitoring working party)). Thus, the proposed B-IBI system is suitable to the Irtysh River, and could serve as one effective measure of environmental monitoring in the river system.