高原深水型湖库水体重金属及营养盐耦合关系探究——以乌江构皮滩水库为例

水体富营养化及重金属污染都是严峻的水污染问题,二者可能存在一定的拮抗作用,但关于重金属与营养盐间耦合机理研究相对较少。本文选取乌江高磷背景的构皮滩水库为研究对象,分析2018年1、4、7、10月的支流表层水、库区分层水和下泄水的营养盐、溶解态重金属及相关水化学参数。通过不同组分间的Pearson相关分析及重金属聚类分析,发现As、Ni、Co与Mn可能主要来自于矿山废水,而Zn、Pb、Cd、Cr主要与生活、农业废水排放有关。Fe、DSi可作为指示重金属与营养盐耦合机制的代表元素,Fe用于表征外源及氧化还原条件的贡献,DSi可指示生物作用(包括吸收、分解等)的参与程度。结合DSi/TDN、As/Fe、Zn/As分析,表明该地区重金属及营养盐间的耦合关系主要受径流、硫酸盐还原作用及颗粒态污染物吸附/解吸等综合作用的影响。该研究为重金属及营养盐耦合机制探究提供一定的理论依据,同时对喀斯特深水型湖库复合污染治理具有重要指导意义。

Study on Coupling Relationship between Heavy Metals and Nutrients in Plateau Deep-water Reservoirs: A Case Study of the Goupitan Reservoir in the Wujiang River Catchment

Eutrophication and heavy metal pollution are all eye-catching water pollution problems, the antagonistic effect may exist between them, though. Few researches had been conducted on revealing interaction mechanisms between heavy metals and nutrients in reservoirs. The Goupitan reservoir in the Wujiang river catchment, a high phosphorus background area, was selected as the research object. The temporal and spatial variations of heavy metals and nutrients in surface waters of tributaries, stratified water within the reservoir and discharged water were analyzed in January, April, July and October, 2018. According to the Pearson correlation analysis and the Cluster analysis among hydrochemical parameters, nutrients and concentrations of dissolved heavy metals, it was deduced that As, Ni, Co and Mn were mainly resulted from the mine wastewater, while Zn, Pb, Cd and Cr were related to domestic and agricultural wastewater discharges. In addition, this study demonstrated that Fe and DSi could be used as representative elements to indicate the coupling mechanism between heavy metals and nutrients, where Fe was used to represent the contribution of exogenous and redox conditions, and DSi indicated the participation degree of biological actions including sorption and decomposition, etc. Combined with ratios of DSi/TDN, As/Fe, Zn/As, it was suggested that the coupling relationship between heavy metals and nutrients in this area was mainly affected by runoff, sulfate reduction, and sorption and desorption of particulate pollutants. Generally, this work had provided more information about sources and interaction mechanism between heavy metals and nutrients, and such had important guiding significance in treating the eutrophication and heavy metal pollution combined problem of karst deep-water reservoirs.