Chemical weathering plays an important role in modulating Earth's climate. However, chemical weathering is usually influenced by multiple factors simultaneously (e.g., climate, topography and lithology), and it is difficult to understand how these variables modulate the effect of chemical weathering on atmospheric pCO2. In this study, we collected and analyzed water chemistry and multiple isotopes (δ34SSO4, δ18OSO4 and δ18OH2O) in the Bailong River catchment to decipher how these variables influence chemical weathering and its effect on atmospheric pCO2. We used the Monte Carlo inversion model to partition the sources of major cations and SO42−, and the results reveal that carbonate weathering is the dominant source contributing cations in river. Sulfide oxidation is the most important source for SO42− and a supply-limited process that is highly dependent on slope. We thus think slope is main factor modulating the effect of chemical weathering on atmospheric pCO2. Steep slope increases sulfide oxidation rate by elevating erosion, resulting in chemical weathering acting as a CO2 source. In contrast, gentle slope could facilitate a thick regolith that contributes long-term silicate weathering and limits sulfide oxidation, resulting in chemical weathering acting as a CO2 sink. And it has been found that the influence of temperature on chemical weathering becomes progressively pronounced with increasing altitude. This study investigated sulfide weathering in eroding Qinghai-Tibet Plateau, highlighting the geomorphologically controlled CO2 effects of chemical weathering.

中文翻译：

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侵蚀调节化学风化对青藏高原大气 pCO2 的影响


化学风化在调节地球气候方面起着重要作用。然而，化学风化通常同时受到多种因素（例如气候、地形和岩性）的影响，并且很难理解这些变量如何调节化学风化对大气 pCO2 的影响。在这项研究中，我们收集并分析了白龙江流域的水化学和多种同位素（δ34SSO4、δ18OSO4 和 δ18OH2O），以破译这些变量如何影响化学风化及其对大气 pCO2 的影响。我们使用蒙特卡洛反演模型对主要阳离子和 SO42− 的来源进行了划分，结果表明碳酸盐风化是河流中贡献阳离子的主要来源。硫化物氧化是 SO42− 的最重要来源，也是高度依赖于斜率的供应受限过程。因此，我们认为斜率是调节化学风化对大气 pCO2 影响的主要因素。陡峭的斜坡通过提高侵蚀作用来增加硫化物氧化速率，导致化学风化作用成为 CO2 源。相比之下，平缓的斜坡可以促进厚厚的风化层，这有助于硅酸盐的长期风化并限制硫化物氧化，从而导致化学风化作用成为 CO2 汇。并且已经发现，温度对化学风化的影响随着海拔的增加而逐渐明显。本研究调查了青藏高原侵蚀中的硫化物风化作用，突出了化学风化作用对 CO2 的地貌控制效应。