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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.
The mechanism of sulfuric acid weathering of carbonates and its relationship with carbon cycling is one of the most important scientific problems in the global carbon cycle research, and the key issue is to identify the source of sulfate. By analyzing the SO42- Sulfur and oxygen isotope composition of the Yangtze River to explore the source of the Yangtze River sulfate and its main controlling factors.The Yangtze River water SO42- content showed an increasing trend year by year and gradually increased.δ34SSO4 and δ18 OSO4 range of -3.5 ‰ ~ 5.6 ‰ and 3.7 ‰ ~ 9.2 ‰, both of which show a significant linear negative correlation.The δ18 OSO4 value increases from upstream to downstream are affected by the spatial composition of δ18OH2O value in the Yangtze River.The results show that the precipitation (acid rain) and Sulfide oxidation is the main mechanism controlling the sulfur and oxygen isotope compositions and sources of river water during the wet season, providing an important theoretical basis for studying chemical weathering and carbon cycle in the Yangtze River Basin.