气候变化领域集成服务门户(CCPortal): Erosional modulation of the balance between alkalinity and acid generation from rock weathering

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DOI	10.1016/j.gca.2023.11.010
	Erosional modulation of the balance between alkalinity and acid generation from rock weathering
	Xu, Sen; Bufe, Aaron; Li, Si-Liang; Erlanger, Erica D.; Ran, Lishan; Zhong, Jun; Yang, Ci-Jian; Zhang, Liwei; Ma, Tingting; Sachse, Dirk
发表日期	2024
ISSN	0016-7037
EISSN	1872-9533
起始页码	368
卷号	368
英文摘要	The balance between alkalinity generation by carbonate and silicate weathering and sulfuric acid generation by sulfide weathering controls the effect of weathering on atmospheric pCO2 over geologic timescales. How this balance varies across environmental gradients remains poorly constrained. Here, we analyze this balance across an erosional gradient of two orders of magnitude in the Three Rivers (Yangtze, Mekong, and Salween Rivers) Headwater Region (TRHR), eastern Qinghai-Tibet Plateau (QTP). By employing major element chemistry and multiple isotopes (delta34SSO4, delta18OSO4, and delta18OH2O) coupled with forward and inverse approaches, we unmix contributions of silicates, carbonates, evaporites, and sulfides to the total weathering budget. Across the TRHR, riverine SO42- is derived mainly from a mixture of an evaporite source with uniform values of delta34SSO4 and delta18OSO4, and a sulfide source that contributes highly variable values of delta34S (-12.2 parts per thousand to +4.1 parts per thousand) and delta18O (-17.7 parts per thousand to -1.6 parts per thousand). Contributions of sulfide oxidation to riverine SO42- vary from 16 % to 94 %, and sulfuric acid consumes 6 % to 63 % of the alkalinity produced by weathering. The fractions of weathering alkalinity derived from carbonate weathering range from 36 % to 98 % relative to silicate weathering. The combination of silicate, carbonate, and sulfide weathering suggests that the instantaneous weathering fluxes of most sampled catchments in the TRHR act as a sink of atmospheric CO2 over timescales shorter than marine carbonate burial (similar to 104 years), but as a carbon source over timescales longer than carbonate burial and shorter than sulfide burial (similar to 107 years). The spatial variability of the balance between alkalinity and acid generation, and, thus, the relationship between chemical weathering and atmospheric pCO2, are largely dependent on lithology. However, within comparable lithologic settings, sulfide and carbonate weathering rates rise with increasing erosion, whereas silicate weathering rates remain constant. Consequently, plateau weathering shifts from a sink to a source of atmospheric CO2 with increasing erosion. These findings suggest that sulfide weathering is more sensitive to erosion than carbonate and silicate weathering, and that it could play an important role in the long-term carbon cycle during mountain building.
英文关键词	Chemical weathering; Pyrite oxidation; Sulfur isotopes; Oxygen isotopes; Qinghai-Tibet Plateau
语种	英语
WOS研究方向	Geochemistry & Geophysics
WOS类目	Geochemistry & Geophysics
WOS记录号	WOS:001200760000001
来源期刊	GEOCHIMICA ET COSMOCHIMICA ACTA
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/293915
作者单位	Tianjin University; University of Munich; Helmholtz Association; Helmholtz-Center Potsdam GFZ German Research Center for Geosciences; Universite de Lorraine; University of Hong Kong; Peking University
推荐引用方式 GB/T 7714	Xu, Sen,Bufe, Aaron,Li, Si-Liang,et al. Erosional modulation of the balance between alkalinity and acid generation from rock weathering[J],2024,368.
APA	Xu, Sen.,Bufe, Aaron.,Li, Si-Liang.,Erlanger, Erica D..,Ran, Lishan.,...&Sachse, Dirk.(2024).Erosional modulation of the balance between alkalinity and acid generation from rock weathering.GEOCHIMICA ET COSMOCHIMICA ACTA,368.
MLA	Xu, Sen,et al."Erosional modulation of the balance between alkalinity and acid generation from rock weathering".GEOCHIMICA ET COSMOCHIMICA ACTA 368(2024).