基于着生藻类生物完整性指数的章江健康状态评价

River Health Assessment of Zhangjiang River Based on the Periphyton Integrated Biotic Index

基于河流着生藻类与水质监测数据,采用着生藻类生物完整性指数法(P-IBI)开展章江健康状态评价,为河流生态系统恢复与水生态修复提供科学依据。通过对28个候选生物参数的分布范围、判别能力和Pearson相关性分析,筛选出由蓝藻属总数、蓝藻分类单元相对多度、可运动硅藻百分比3个核心指数组成的章江P-IBI指标体系,并根据其参照点的25%分位数值,确定章江流域河流健康评价标准。结果表明,章江流域P-IBI平均得分为1.91,河流健康状态为一般状态。9个采样点中,2个处于健康状态,2个良好状态,2个一般状态,3个较差状态;相关性分析表明,P-IBI与高锰酸钾指数(COD_(Mn))、五日生化需氧量(BOD_(5))、总磷(TP)、氨氮(NH_(4)^(+))、氧化还原电位(ORP)等水环境指标呈现显著负相关。从空间尺度看,河流健康状态从上游区到下游区呈现逐渐变差的趋势,这与河流沿线城市和产业发展状况密切相关。着生藻类生物完整性指数的河流健康评价结果与实际状况基本吻合,说明采用P-IBI法可以较好地反映河流健康状况。

In this study,we investigated and analyzed the community structure of periphyton and physicochemical water quality parameters of Zhangjiang River in the Poyang Lake basin.The aquatic ecosystem health of the river was then quantitatively evaluated based on the integrated periphyton biotic index(P-IBI)that was developed as part of the investigation.We aimed to provide scientific evidence for the aquatic ecological restoration of Zhangjiang River,and a reference for river health evaluation based on periphyton.In September and November of 2021,periphyton and water samples were collected at nine transects of the upper,middle and lower Zhangjiang River,with three parallel samples for each transect.Periphyton samples were identified and counted,and the water samples were used for the determination of water environmental factors,including dissolved oxygen(DO),oxidation-reduction potential(ORP),pH,electric conductivity(EC),permanganate chemical oxygen demand(COD_(Mn)),5-day biological oxygen demand(BOD_(5)),total nitrogen(TN),total phosphorus(TP)and ammonia nitrogen(NH_(4)^(+)).Using analysis of the distribution range,discriminative ability,and Pearson correlation of 28 candidate biological parameters,three core indices(total number of cyanobacteria genera,relative abundance of cyanobacteria taxonomic units,and percentage of motile diatoms)were identified to establish the P-IBI evaluation system for Zhangjiang River.Based on the 25%percentile value of reference sites,the evaluation standard for river health in the Zhangjiang River basin was established.The river health was then assessed according to the P-IBI evaluation system.A total of 100 periphyton species from 6 phyla were collected during the investigation,including 37 species of Bacillariophyta,28 species of Chlorophyta,22 species of Cyanophyta,6 species of Euglenophyta,4 species of Chrysophyta,and 3 species of Cryptophyta.The average biomass and density of the periphyton algae were 0.224 mg/cm^(2) and 23.019×10^(4) ind/cm^(2),presenting obvious differences among the 9 transects.The average values of the P-IBI scores in Zhangjiang River was 1.91,and its health status was fair.Among the 9 sampling transects,2 sites were healthy,2 sites were sub-healthy,2 sites were fair,and 3 sites were poor.The P-IBI scores presented significant negative correlations with COD_(Mn),BOD_(5),TP,NH_(4)^(+) and ORP.Spatially,the health status of the river gradually deteriorated from upstream to downstream and was closely related to the development of cities and industries along the river.River health evaluation using the P-IBI was generally consistent with observed river conditions,indicating that the P-IBI method well reflects river health.