Assessment of climate impacts on the karst-related carbon sink in SW China using MPD and GIS

Abstract

Riverine carbon fluxes of some catchments in the world have significantly changed due to contemporary climate change and human activities. As a large region with an extensive karstic area of nearly 7.5 × 10 5 km 2 , Southwest (SW) China has experienced dramatic climate changes during recent decades. Although some studies have investigated the karst-related carbon sink in some parts of this region, the importance of climate impacts have not been assessed. This research examined the impacts of recent climate change on the karst-related carbon sink in the SW China for the period 1970-2013, using a modified maximal potential dissolution (MPD) method and GIS. We first analyzed the major determinants of carbonate dissolution at a spatial scale, calculated the total karst-related carbon sink (TCS) and carbon sink fluxes (CSFs) in the SW China karst region with different types of carbonate rocks, and then compared with other methods, and analyzed the causes of CSFs variations under the changed climate conditions. The results show that the TCS in SW China experienced a dramatic change with regional climate, and there was a trend with TCS decreasing by about 19% from 1970s to 2010s. This decrease occurred mostly in Guizhou and Yunnan provinces, which experienced larger decreases in runoff depth in the past 40 years (190 mm and 90 mm, respectively) due to increased air temperature (0.33 ℃ and 1.04 ℃ , respectively) and decreased precipitation (156 mm and 106 mm, respectively). The mean value of CSFs in SW China, calculated by the modified MPD method, was approximately 9.36 t C km-2 a-1. In addition, there were large differences in CSFs among the provinces, attributed to differences in regional climate and to carbonate lithologies. These spatiotemporal changes depended mainly on hydrological variations (i.e., discharge or runoff depth). This work, thus, suggests that the karst-related carbon sink could respond to future climate change quickly, and needs to be considered in the modern global carbon cycle model.

Influence of different geographical factors on carbon sink functions in the Pearl River Delta

“…There has been some research into factors influencing land use carbon sink effects within highly urbanized areas. The effect of carbon sinks in urban ecosystems has been examined from the perspectives of climate factor 3 and climate change 4 , different land use types 5–12 and land use change 13 , land use management 14 , transportation activities 15 , locational conditions 16 , the level of urbanization 1 , and so on. The urbanization process extensively influences the quantity, types, and spatial distribution patterns of land use, with the carbon sink function of different land uses changing accordingly.…”

Change Detection of Soil Formation Rate in Space and Time Based on Multi Source Data and Geospatial Analysis Techniques

“…We used the MPD method to calculate the dissolution rate of limestone in China, which had been applied in quantifying karstification at global and regional scales [42][43]. The intensity of karstification can be obtained by the MPD method if the temperature, precipitation and evapotranspiration of a given area are known.…”

“…Based on the usual equations for the dissolution of calcite at equilibrium given in Equation (2), Gombert created the MPD method of Equation (3) for carbonate zones with the assumption that the chemical reactions were at equilibrium in local hydrological, meteorological and geochemical conditions [42][43][44][45].…”

“…The MPD method is applicable to all limestone areas [42][43]45]. In this study, we calculate the dissolution rate of carbonate rock on the basis of the specific corrodibility of other rocks in the carbonate rock and limestone.…”

“…However, in pixels, the actual runoff depth of areas, such as Yuan, is difficult to determine through computations. Therefore, the method in [42,43] is adopted. The difference between precipitation and evaporation to replace the actual runoff depth may have a certain deviation between the two processes.…”