Impact Of Allogenic Water On The Karst Carbon Sink In Typical Dolomite Basin

Since the Industry Revolution, a large number of CO2 that from human activities released into the atmosphere has been causing global climate warming. Looking for the carbon sink and its process have become a common focus of both the international and domestic society. Due to the global carbonate distribution area is wide, water-rock interaction of the soluble rock and the potential consumption of CO2 is considerable. Accelerated by allogenic water, karst carbon sink influenced by karstfication in dolomite basins should not be ignored.Liangcha River basin in Shibing of Guizhou Province, which is characterized by its clasolite in upper reaches and the Cambrian pure dolomite in midlle-lower reaches, was selected as the study area. It belongs to subtropical region. Based on collecting, sorting, and analyzing a large number of basic data basis, the study area was investigated and the monitoring points determined. The p H, DO, EC, HCO3- and flow rate of the sampling points were monitored per month, and water were sampled to test the concentration of deliquescing anion and cation from November 2014 to July 2015. The purpose is to estimate accurately the karst carbon sink quantity of the basin from the allogenic water which originated in clastic rock area to the dolomite water through the middle and lower reaches. The results showed that:⑴ Controlled by the action of the lithology, the hydrochemical type of the water respectively shows HCO3--Ca type in the upper reach and HCO3--Ca·Mg type in the lower reach after flowing through the dolomite area.⑵In dry season and flood season, the concentration of DIC increased from 10 times to 22 times from the spring exposed(represented by HTP) to form surface runoff, and then flows to the dolomite region, finally to export the basin.⑶The SIc and SId of allogenic water was increased from the spring exposed to the export in the clastic rock catchment area where the SIc and SId do not reach saturation and still have strong corrosion ability. The dissolved Ca2+ and Mg2+ concentration increase, meanwhile the SIc and SId rise and reach saturation when the water flew through the dolomite region with the Dolomite’s corrosion in the river.Using solute load method, the net carbon sink of allogenic water and the increasing carbon sink in dolomite region in the study area was estimated. Meanwhile, rock samples in the Cambrian Gaotai formation were collected and the rock ore were analysed to make a deep analysis of the influencing factors of allogenic water on the karst carbon sink in typical dolomite basin. It was found that:⑴The net carbon sink in DZ is 21151.8 kg/km2, and the increasing carbon sink in LCHD is 42753.2 kg/km2.⑵The impact of allogenic water on the karst carbon sink in typical dolomite basin shows four aspects: the chemical composition of allogenic water, the catchment area and flow rate, the corrosion of dolomite and the water-rock action time.