乐安河源区水库沉积硅藻分布特征及环境响应

Distribution Characteristics and Environmental Response of Diatoms Deposited in Reservoirs in the Source Region of Le an River

目前在乐安河流域内展开的河流重金属的污染研究亟待发掘。为充分阐明乐安河河源区水库环境特征及其环境变化驱动过程,以婺源县境内不同生态环境与开发背景的清华和石井水库为研究对象。通过实验记录沉积柱岩芯中硅藻种类及理化指标,并结合现代监测资料及多元统计方法,分析影响水库中沉积硅藻组合群落变化及沉积环境变化的环境特征驱动因子。结果表明,水库营养水平随深度至表层逐渐升高,沉积物污染评价也揭示了营养物质的汇集过程。沉积硅藻物种耐污种和富营养化指示种取代由普生种和清洁指示种成为优势,代表性物种为Achnanthidium minutissima、Navicula minima。多元统计分析结果表明,TP、TN及TP、TOC分别为清华和石井水库硅藻组合群落结构分布的主要驱动因子(p<0.05)。18项硅藻指数的箱线图分析结果显示,CEE、LOBO指数被筛选并表现出良好的评价适宜性及相关性。不同人类活动方式影响库区内输入的外源物质,从而驱动硅藻群落的演替,2座水库皆有向富营养化迈进的趋势。

At present,the study of heavy metal pollution in the Le an River Basin should be explored.To fully elucidate the environmental characteristics and change-driven processes of reservoirs in the source region of the Le an River,this paper employs Qinghua and Shijing reservoirs with different ecological environments and development backgrounds as research objects.Experimental records of diatom species and physicochemical indicators in sedimentary column cores are conducted,and meanwhile combined with modern monitoring data and multivariate statistical methods,environmental characteristics driving factors affecting changes in sedimentary diatom assemblages and sedimentary environment in reservoirs are analyzed.The results show that nutrient levels in the reservoirs gradually increase with the depth to the surface,and the sediment pollution evaluation also reveals the collection process of nutrients.Universal and cleaning indicator species have been replaced by fouling-tolerant and eutrophication indicator species of sedimentary diatoms,with representative species being Achnanthidium minutissima and Navicula minima.The multivariate statistical analysis results show that TP,TN,TP,and TOC are the main driving factors of diatom community structure distribution in Qinghua and Shijing reservoirs respectively(p<0.05).Box plot analysis results of 18 diatom indices reveal that CEE and LOBO indices are screened and show sound evaluation suitability and correlation.The input of exogenous materials into the reservoirs is affected by different anthropogenic practices to drive the succession of the diatom community,with a trend towards eutrophication in both reservoirs.