Abstract

Chemical weathering in a groundwater basin is a key to understanding global climate change for a long-term scale due to its association with carbon sequestration. The present study aims to characterize and to quantify silicate weathering rate (SWR), carbon dioxide consumption rate and carbonate weathering rate (CWR) in hard rock terrain aided by major ion chemistry. The proposed study area Shanmuganadhi is marked with superior rainfall, oscillating temperature and runoff with litho-units encompassing charnockite and hornblende–biotite gneiss. Groundwater samples (n = 60) were collected from diverse locations and analysed for major chemical constituents. Groundwater geochemistry seems to be influenced by geochemical reactions combining dissolution and precipitation of solids, cation exchange and adsorption along with minor contribution from anthropogenic activities. The SWR calculated for charnockite and hornblende–biotite gneiss was 3.07 tons km⁻² year⁻¹ and 5.12 tons km⁻² year⁻¹, respectively. The calculated CWR of charnockite and hornblende–biotite gneiss was 0.079 tons km⁻² year⁻¹ and 0.74 tons km⁻² year⁻¹, respectively. The calculated CO₂ consumption rates via silicate weathering were 1.4 × 10³ mol km⁻² year⁻¹ for charnockite and 5.8 × 10³ mol km⁻² year⁻¹ for hornblende–biotite gneiss. Lithology, climate and relief were the key factors isolated to control weathering and CO₂ consumption rates.

中文翻译：

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印度南部Shanmuganadhi的化学风化和大气二氧化碳（CO 2）消耗：地下水地球化学的证据

摘要

地下水盆地中的化学风化是长期了解全球气候变化的关键，因为它与碳固存有关。本研究旨在表征和定量在主要离子化学辅助下的坚硬岩石地形中的硅酸盐风化速率（SWR），二氧化碳消耗速率和碳酸盐风化速率（CWR）。拟议中的研究区Shanmuganadhi具有优越的降雨，振荡温度和径流的特征，岩石单元包括长方岩和角闪石-黑云母片麻岩。地下水样品（n = 60）从不同地点收集并分析主要化学成分。地下水地球化学似乎受地球化学反应的影响，这些化学反应结合了固体的溶解和沉淀，阳离子交换和吸附以及人为活动的微小贡献。夏诺克岩和角闪石-黑云母片麻岩的SWR计算分别为3.07吨km - ² 年^-1和5.12吨km - ² 年^-1。紫苏花岗岩和角闪石，黑云母片麻岩的计算无缝线路是0.079吨千米^-2 年^-1 0.74亿吨公里^-2 年^-1，分别。计算出的CO ₂通过硅酸盐风化消耗率分别为1.4×10 ³ 摩尔公里^-2 年^-1为紫苏和5.8×10 ³ 摩尔公里^-2 年^-1为角闪石黑云母片麻岩。岩性，气候和救济是控制风化和CO ₂消耗率的关键因素。