Abstract
ABSTRACTThis paper presents new insights into the global carbon cycle related to CO2 consumption from chemical denudation in heavily glacierised Himalayan catchments. Data from previous studies of solute concentrations from glacierised catchments were reprocessed to determine the regional scale of CO2 consumption and solute hydrolysis. The results show that ~90% of the SO42− is derived from crustal sulphide oxidation and ~10% from aerosols and sea salts. However, HCO3− flux calculation estimates contribution from sulphide oxidation to carbonate dissolution (SO-CD) (~21%), similar to the contributions from silicate dissolution and simple hydrolysis (~21 and ~20%, respectively). Furthermore, the atmospheric CO2 consumption estimations suggests 10.6 × 104 mole km−2 a−1 (19%) through silicate weathering, 15.7 × 104 mole km−2 a−1 (28%) through simple hydrolysis, 9.6 × 104 mole km−2 a−1 (17%) through SO-CD reaction and 5.9 × 104 mole km−2 a−1 (11%) through carbonate carbonation reaction. Our solute provenance calculations clearly indicate that HCO3− production and CO2 consumption via silicate weathering reactions is balanced by the simple hydrolysis and coupled SO-CD process. This shows a counter mechanism operating in subglacial environments of the Himalaya as a source of CO2 to runoff rather than a sink.
Highlights
AND BACKGROUNDWeathering is a ubiquitous phenomenon that operates at different rates throughout the Earth’s surface
Evaporite dissolution is small in glacierised basin in the Himalaya comparing to carbonate dissolution (CD) and sulphide oxidation (e.g. Sharma and others, 2013; Singh and others, 2015a, b)
An analysis of large rivers indicates that a good correlation exists between CO2 consumption and silicate weathering flux (Gaillardet and others, 1999) and its consumption in terms of chemical weathering is associated with the tectonic uplift of the Himalaya (Sharp and others, 1995)
Summary
AND BACKGROUNDWeathering is a ubiquitous phenomenon that operates at different rates throughout the Earth’s surface. Chemical weathering and carbon cycling has affected the global climate system over geological time scales (Gislason and others, 2009; Torres and others, 2017). The estimation of CO2 release as a result of SO-CD involving glacial sediments is important to explain the potential influence of chemical weathering in glacial–interglacial cycles of the Earth’s climate (Hodson and others, 2000; Torres and others, 2017). This depends upon the burial and subsequent oxidation of the carbon and sulphur compounds involved in reaction (Berner and others, 2000)
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