2013..Acta Geologica Sinica(),87(5):1472-1473
Important Progress Made in the Study of Chinese Geological Carbon Sink Potential
HAO Ziguo FEI Hongcai LIU Lian Susan TURNER
1 Chinese Academy of Geological Sciences, Beijing 100037, China
2 Editorial office of Acta Geologica Sinica (English edition)
From 2010 to 2012, geologists at the Institute of Karst Geology the Chinese Academy of Geological Sciences carried out the “Chinese Geological Carbon Sink Projects Research”. They did investigation and research work according to three aspects of carbon sink: karst, soil, and mineral, and achieved important results. Through the investigation and test of karstification in the Guijiang River catchment of Guangxi Province, geologists obtained test data from more than 100 water points, and therefrom calculated the CO2 flux of unit area as 41 t/km2•a in the drainage area. Through the carbon sink investigation of Shanxi Huoquan Spring, Thunder Temple Spring and other spring areas in North China, geologists have preliminarily calculated that the CO2 flux of unit area was 5.3 t/km2•a in the North China karst area. According to the results of the annual survey, the total amount of karst carbon sink in China reaches about 60 million tons each year, accounting for more than 1/10 of the world karst carbon sink (600 million tons). At the same time, statistics show that atmospheric CO2 consumed by carbonate weathering of major rivers in China is 1260–1759×109 mol/yr, accounting for more than 1/10 of the atmospheric CO2 consumed by global rivers (12300×109 mol/yr). Thus karstification in China plays an important role in reducing CO2 content in the global atmosphere. Through this recent research on soil carbon sink, geologists also found that different land-use modes had great effect in karst carbon sink, so that carbon sink produced by karstification increases 2–8 times from rocky desertification to scrub to secondary forest. Carbon sink produced by karstification can be improved by 5.71–7.02 t/km2•a from farmland to secondary forest. Research also shows that dissolved organic carbon content in the soil in karst areas is 1/5 in acid soil. If 50 tons of sludge is added per hectare of soil, after 6 months per kilogram of soil organic carbon can increase on average 1.7 grams. Therefore they thought: a wide range of karst rocky desertification comprehensive treatments has an important effect for the improvement of the regional ecological environment, for maintenance of ecological security, and for promotion of the global CO2 emission reduction. Moreover, modifying karst soil with the sludge would not only improve the soil properties but also greatly improve soil carbon sequestration. This first major investigation of the Chinese mineral sink shows that consumption rate of atmospheric CO2 by silicate weathering in a basalt drainage area was 6×105 mol/km2•a, higher than the world average level; serpentine ultrabasic minerals and their total tailings storage CO2 can reach 13.5 trillion tons, equivalent to 2000 x Chinese CO2 release in 2005. Thus, in addition to carbonate karstification that can form a large number of geological carbon sinks, basalt and ultramafic rock mineral weathering also has huge potential for carbon sink. Preliminary estimates of the atmospheric CO2 amount consumed by silicate weathering in China is about 305–811×109 mol/year, accounting for 3.5%–9.3% of the global mineral consumption of atmospheric CO2 (8700×109 mol/yr). Thus, as geologists worldwide carry out further studies on the geological environment of CO2 emission reduction, then CO2 underground storage is conditional, and the prospects for solving this global problem are very bright.