摘要
古土壤和湖泊中的有机质碳同位素与磁化率指标被广泛应用于古气候的重建。但由于各地自然条件的差异,其气候意义具有一定的区域性。通过对中国秦岭到内蒙古北部的中蒙边境(34°N～43°N)连续剖面上的102个采样点的表层土壤样品的有机质碳同位素和磁化率进行测定,并搜集了该区域部分站点的降水资料。研究表明有机质碳同位素波动在-22‰～-30‰之间,其碳同位素值与降水量存在显著的线性负相关关系。磁化率与年均降水量也存在显著的函数关系,总体上磁化率随着年降水量的增加而增加。研究进一步证明,在中国干旱和半干旱区,表土中的有机质碳同位素δ13C和磁化率对年降水量具有显著的指示作用,因此可以用古土壤中的有机质碳同位素和磁化率作为代用指标,来反映古降水的变化。
The data of carbon isotope in organic matter and magnetic susceptibility of paleosol and lacustrine sediment are extensively used to reconstruct the paleoclimatic change.Because the natural environment is different from the different regions,the climatic significance of carbon isotope in organic matter and magnetic susceptibility of paleosol is regional in a certain extent,and it is necessary to research the climatic significance of carbon isotope in organic matter and magnetic susceptibility of topsoil in some typical regions.There is a significant gradient distribution of precipitation and temperature in the arid and semiarid regions in north China,which can provide the ideal fields for verifying the significance of all the paleoclimatic indexes.In this paper 102 soil samples sampled along a section from the Qinling Mountains to the China-Mongolia border were sampled , and their carbon isotope in organic matter and magnetic susceptibility of topsoil are measured.Moreover,the data of precipitation are also collected from some meteorological stations in the study area.The results show that the carbon isotope varies in a range from -30‰ to -22‰,there is a negative linear correlation between the change of carbon isotope in organic matter and the annual precipitation.There is also a significant functional relation between the magnetic susceptibility and the annual precipitation.Generally,the value of magnetic susceptibility increases with the increase of annual precipitation.The study further proves that the data of carbon isotope in organic matter and the magnetic susceptibility of topsoil in the arid and semiarid regions in north China can be used to reveal the distribution of precipitation.Thus, the data of carbon isotope in organic matter and of the magnetic susceptibility of paleosol and lacustrine sediment can be regarded as the indexes to reveal the change of paleaoprecipitation.
出处
《干旱区地理》
CSCD
北大核心
2005年第3期311-315,共5页
Arid Land Geography
基金
国家杰出青年基金项目资助(40025105)
关键词
有机质碳同位素
磁化率
表层土壤
降水
干旱半干旱区
carbon isotope in organic matter
magnetic susceptibility
topsoil
precipitation
arid and semiarid regions.
