黄河水沙调控过程中河水溶解性硫酸盐硫和氧同位素组成特征

Characteristics of sulfur and oxygen isotopes of dissolved sulfate in response to water-sediment controlling in the Yellow River

针对黄河水沙调控过程对黄河流域元素循环的影响问题,选择2012年黄河水沙调控过程中河水硫酸盐作为研究对象,借助硫酸盐硫和氧同位素来识别河水硫酸盐以及排沙过程泥沙水中硫酸盐来源。结果表明,三门峡水文站河水硫酸盐硫和氧同位素值范围分别为7.9‰~12.5‰(均值为10.1‰)和4.8‰~8.4‰(均值为7.1‰),小浪底水文站河水硫酸盐硫和氧同位素值范围分别为8.5‰~9.1‰(均值为8.6‰)和5.6‰~7.4‰(均值为6.6‰),花园口水文站河水硫酸盐硫和氧同位素值范围分别为8.7‰~12.0‰(均值为10.0‰)和6.5‰~8.5‰(均值为7.7‰);黄河水沙调控期间泥沙水硫酸盐硫和氧同位素值随着泥沙含量增加而逐渐降低,显示水库底部沉积物中硫化物和有机硫氧化产生硫酸盐进入河水,这种趋势在三门峡以及小浪底水库水沙调控期间表现明显,但花园口水文站则不明显,可能与伊洛河和沁河支流汇入有关;黄河水沙调控期间河水溶解性硫酸盐重要来源包括石膏溶解、硫化物和有机硫氧化以及生活污水等;黄河水沙调控过程影响河流硫循环过程,导致沉积物中硫化物氧化产生硫酸盐,进而增加下游硫酸盐的输出通量,三门峡水库泥沙排泄引起硫酸盐增加的比例约占24.2%,小浪底水库泥沙排泄引起硫酸盐增加的比例约占8.8%。研究结果为黄河流域人工水沙调控工程对河流元素循环的影响研究提供科学依据。

To elucidate how the water-sediment controlling process affects element cycling in the Yellow River Basin, water samples were collected during water-sediment controlling in 2012, and then sulfur and oxygen isotopes were analyzed. The results showed that sulfur and oxygen isotope values of river water samples in Sanmenxia station varied from 7.9‰ to 12.5‰ （with an average of 10.1‰） and from 4.8‰ to 8.4‰ （with an average of 7.1‰）, respectively. Sulfur and oxygen isotope values of river water samples in Xiaolangdi station ranged from 8.5‰ to 9.1‰ （with an average of 8.6‰） and from 5.6‰ to 7.4‰ （with an average of 6.6‰）, respectively. Sulfur and oxygen isotope values of river water samples in Huayuankou station varied from 8.7‰ to 12.0‰ （with an average of 10.0‰） and from 6.5‰ to 8.5‰ （with an average of 7.7‰）, respectively. Sulfur and oxygen isotope values of sulfate in river water decreased with the increases of siltcontents in the river water samples, indicating that the “newly produced sulfate” was mainlyderived from oxidation of sulfide and organic sulfur during water-sediment controlling, especially in Sanmenxia station and Xiaolangdi station. However, such differences of sulfate isotopes were not significant in Huayuankou station due to the mixing processes impacted by the tributaries of Yiluo River and Qinhe River. The range of sulfate isotopes suggested that dissolved sulfate in river water was mainly controlled by dissolution of gypsum, oxidation of sulfide and organic sulfur and sewage water. Watersediment controlling process affected sulfur cycling in Yellow River, in that it can release sulfate by oxidation of sulfide and organic sulfur in sediment, and thus increases sulfate flux to the downstream. The proportion of sulfate released into river by water sedimentcontrolling was about 24.2% in Sanmenxia Reservoir and 8.8% in Xiaolangdi Reservoir, respectively. The results improved our understanding of water-sediment controlling on the riverineelement cycling in the Yellow River Basin.