基于硫氧同位素的菏泽市主要河流硫酸盐来源解析

Source Analysis of Sulfate in the Major Rivers of Heze City Based on Stable Sulfur and Oxygen Isotopes

为探明菏泽市河流中硫酸盐污染的主要来源,以洙赵新河流域和东鱼河流域为例,利用硫酸盐(SO_(4)^(2-))浓度、硫氧同位素(δ^(34)S_(SO_(4))和δ^(18)O_(SO_(4)))研究菏泽市主要河流SO_(4)^(2-)的时空分布特征和来源。结果表明:(1)研究区河流中(δ^(34)S_(SO_(4))和δ^(18)O_(SO_(4)))值的变化总体表现为枯水期>平水期>丰水期,且洙赵新河流域δ^(34)S_(SO_(4))值和δ^(18)O_(SO_(4))值变化范围更大,来源更加复杂;(2)丰水期研究区SO_(4)^(2-)主要来源为土壤携带以及污废水排放,贡献率均在30%以上;(3)平水期和枯水期洙赵新河流域SO_(4)^(2-)主要来源为生活污水与工矿企业生产废水,平均贡献率均在50%以上,东鱼河流域主要来源为硫化物氧化,平均贡献率超过30%。

Soluble sulfate(SO_(4)^(2-))has large effects on river water quality and the regional hydrogeochemical cycle.The main rivers in Heze City all flow into Nansi Lake,an important water storage hub for the Eastern Route of the South-to-North Water Diversion Project.Previous studies have suggested that the high SO_(4)^(2-)concentration in Nansi Lake is primarily due to inflowing rivers.In this study,the main rivers in Heze City(Zhuzhaoxin River basin and Dongyu River basin)were selected for research,and we analyzed the spatio-temporal distribution,primary sources and their relative contribution to SO_(4)^(2-)in the Zhuzhaoxin River basin and Dongyu River basin using stable sulfur and oxygen isotope analysis.Our aim was to provide data support for controlling the concentration of SO_(4)^(2-)in regional rivers and ensuring the water quality of the South-to-North Water Diversion Project.In October and December of 2020,and April and August of 2021,samples of surface and underground water,and river sewage outfalls were collected at 75 sampling sites for analysis of physicochemical parameters and the determination ofδ^(34)S_(SO_(4))andδ^(18)O_(SO_(4))for source identification.Results show:(1)The concentration of SO_(4)^(2-)in the surface water of the study area was relatively high,and most of the water samples exceeded the standard limit of SO_(4)^(2-)for drinking water as defined in the Environmental Quality Standards for Surface Water(250 mg/L).The variation ofδ^(34)S_(SO_(4))andδ^(18)O_(SO_(4))in the rivers generally followed the order,dry season>normal season>flood season,and the ranges ofδ^(34)S_(SO_(4))andδ^(18)O_(SO_(4))in the Zhuzhaoxin River basin were larger with a more complex mix of sources.(2)During flood season,the primary sources of SO_(4)^(2-)in study area were attributed to soil erosion and wastewater discharge,and both contributed over 30%of the total.(3)During the normal and dry seasons,the primary sources of SO_(4)^(2-)in the Zhuzhaoxin River basin were wastewater discharges from domestic,industrial and mining enterprises,with an average combined contribution rate above 50%.The primary sources in Dongyu River basin was sulfide oxidation,with an average contribution rate of over 30%.The data from this investigation supports efforts to protect water quality in the South-to-North Water Diversion Project.