【摘要】 碳酸盐岩的硫酸风化机制及其与碳循环的关系是全球碳循环研究中最为关注的科学问题之一,其关键问题是识别硫酸盐来源.通过分析长江干流丰水期SO42-浓度及其硫、氧同位素组成特征,探讨长江硫酸盐的来源及其主要控制因素.长江河水SO42-含量呈现逐年增加的趋势,并且年增幅度逐渐加大.δ34SSO4和δ18 OSO4变化范围为-3.5‰~5.6‰和3.7‰~9.2‰,二者呈现显著的线性负相关关系.δ18 OSO4值从上游到下游的增加趋势受长江水δ18 OH2O值的空间组成特征的影响.研究表明,大气降水(酸雨)和硫化物氧化是控制长江干流丰水期河水硫、氧同位素组成及其来源的主要机制,为研究长江流域化学风化侵蚀作用和碳循环过程提供重要的理论依据.更多还原

【Abstract】 Crustal weathering by sulfuric acid and its relationship with carbon cycling is a subject of greatest concern in the domain of global carbon cycling,with its key issue of the identification of riverine sulfate sources.In this study,stable sulfur and oxygen isotope compositions of riverine sulfate in the mainstream of the Yangtze River during rainy season are determined to trace the riverine sulfate sources and controlling factors.The SO42-concentration keeps increasing with ever-increasing annual growth rate.The isotope compositions of dissolved sulfate in the Yangze River range from-3.5‰ to 5.6‰ forδ34 SSO4 and from3.7‰to 9.2‰forδ18 OSO4,showing a significantly negative linear correlation betweenδ34SSO4andδ18 OSO4.The tendency of increasedδ18 OSO4 values from upstream to downstream is controlled byδ18 OH2 Ovalues of the Yangtze River water.It is indicated that atmospheric acid deposition and sulfide oxidation are dominant sources of dissolved sulfate in the Yangze River.This study offers theoretical basis which facilitates further environmental explorations for chemical weathering of carbonate and carbon cycling.更多还原