基于大型底栖动物快速评价的三峡库尾城市化支流梁滩河流域健康评估

Health assessment of Liangtan River Basin,a tributary of urbanization at the tail of the Three Gorges Reservoir,based on rapid assessment of macroinvertebrates

为了给三峡库尾重庆市主城区段次级河流、其他城市化河流的健康评价提供快速有效的方法,本实验在位于三峡库尾重庆主城区段的嘉陵江一级支流梁滩河流域布置监测点位,同步采集大型底栖动物和环境因子,利用大型底栖动物快速生物评价指数进行河流健康评估研究。结果显示:梁滩河共采集到大型底栖动物58种,Shannon-Wiener指数在0.06~2.23内,流域主要优势类群为耐受污染的寡毛类和摇蚊科种类,呈典型的城市化河流特征;PCA分析结果表明两轴共解释了59.3%的环境变异,表明水温(T)、硝酸盐(NO-3)、溶解氧(DO)、氧化还原电位(ORP)是影响梁滩河的关键环境因子;初步筛选的4大类共8个快速生物评价指数中,物种数(S)和BMWP指数呈极显著相关性,且均与其他指数相关性不显著,其余指数间相关性均达到显著水平;回归分析表明,除BPI指数、jFD指数、BP指数外,其余5种评价指数与T、NO-3、ORP、pH等部分指标表现出较高的相关性,在不同程度上均可以较显著地反映人类活动对流域水质的影响;综合分析后,筛选出物种数S、GBI指数和FBI指数共同构建综合评价指数进行综合评价,评价梁滩河总体健康状况为“理想状况~病态”,总体上与综合水质标识指数法评价结果变化规律相似,但由于流域总体污染水平较高(各点位水质均在Ⅴ类以上)而各点位评价结果差异较大。选定的指数也较为适合与梁滩河地形地貌、城市化水平较为接近的其他三峡库尾次级河流。

This study provides a fast and effective method for the health evaluation of secondary rivers and other urbanized rivers in the main urban area of Chongqing at the end of the Three Gorges Reservoir.Monitoring sites were arranged in the Liangtan River Basin,a first-class tributary of the Jialing River,located in the main urban area of Chongqing at the end of the Three Gorges Reservoir.Macrobenthos and environmental factors simultaneously were collected and the macrobenthos rapid biological evaluation index were used to conduct river health assessment research.The results showed that 58 species of macrobenthos were collected in Liangtan River.The Shannon-Wiener index was in the range of 0.06 to 2.23.The main dominant groups in the basin were pollution-tolerant oligochaetes(Limnodrilus sp.Branchiura sowerbyi,etc.)and Chironomidae species,showing typical characteristics of urbanized rivers.The results of PCA analysis explained 59.3%of the environmental variation in the two axes,indicating that water temperature(T),nitrate(NO-3),dissolved oxygen(DO),and redox potential(ORP)were the main environmental factors affecting the Liangtan River.Among the 8 rapid biological evaluation indiced in the 4 categories initially screened,the number of species S was significant correlated with the BMWP index(r=0.927,P<0.01).There was no significant correlation with other indices(r was 0.022~0.501,P>0.05).The correlations between the other indices reached a significant level(r is 0.604-0.947,P<0.05).Regression analysis showed that except for BPI index,jFD index,and BP index,the other five evaluation indexes showed a high correlation with some indexes such as T,NO-3,ORP,pH,etc.(R 2 is 0.322~0.546,P<0.05),which can reflect the impact of human activities on water quality of the watershed in different degrees.After a comprehensive analysis,the number of species S,the GBI index and the FBI index were screened out to construct a comprehensive evaluation index for comprehensive evaluation jointly.In general,the variation law of the evaluation results of the comprehensive water quality labeling index method is similar.Still,due to the basin′s high pollution level(the water quality of each point is above Class V),the evaluation results of each issue are quite different.Other secondary rivers at the tail of the Three Gorges Reservoir with similar topography and urbanization level of Liangtan River.