干旱区生态环境知识资源中心

This paper analyzed stable carbon and oxygen isotopic changes in organic matter (delta C-13(SOM)) and disseminated carbonate (delta C-13(SC) and delta O-18(SC)) in four terra rossa profiles in Gouzhou, southwestern China. The objectives were to understand more information about climate change in this area and to determine whether the isotope values of disseminated carbonate in terra rossa preserved a record of environmental change and to distinguish environmental sources that may have influenced the isotopic chemistry. Results suggested that carbonate in terra rossa is mainly pedogenic carbonate, and its formation is closely associated with root activities. The delta C-13(SOM) variations indicate a climate change into warmer and drier conditions at about 6000-8000 a BP, 12000-14000 a BP and 28000 a BP. Plants were more depleted in delta C-13 when carbonate precipitated. Compared with the delta C-13(SOM), the delta C-13(SC) tends to reflect more average climate change information. Most large variations of the delta C-13(SC) and delta C-13(SOM) between adjacent sampling layers are accompanied with the change in soil color and texture, suggesting a certain connection between the delta C-13 and the soil properties. This study found a positive linearity between delta C-13(SC) and delta O-18(SC); a striking different value and correlation coefficient in different sites may provide a meaningful signal of regional climate change.