摘要
Surface soil samples collected over a high spatial resolution in eastern China were analyzed for carbon isotope composition(δ 13C) of total organic carbon(TOC) and higher plant-derived long-chain n-alkanes,with the latter reported as weighted mean values.The two sets of δ 13C values are significantly correlated and show similar trends in spatial variation.The spatial distribution of δ 13C shows less negative values in the mid-latitudes between 31°N and 40°N and more negative ones at higher and lower latitudes.This is consistent with previously reported carbon isotope data from surface soil phytoliths in the same region and suggests that the mid-latitude area provides relatively favorable growing conditions for C4 plants.Furthermore,δ 13C values of both TOC and long-chain n-alkanes from 12 surface soil samples collected from a small grassland in north China displayed similar carbon isotope values and the difference between paired δ 13C of a soil samples remains relatively constant.Our data demonstrate that in eastern China,soil δ 13C composition of both TOC and long-chain n-alkanes is effective indicators of C3/C4 ratios of the prevailing vegetation.This work suggests that -22‰ and -32‰ are good estimated end members for the weighted mean δ 13C values of long-chain n-alkanes(C27,C29 and C31 n-alkanes) from soils under dominant C4 or C3 vegetation,allowing us to reconstruct paleovegetation trends.
Surface soil samples collected over a high spatial resolution in eastern China were analyzed for carbon isotope composition （δ^13C） of total organic carbon （TOC） and higher plant-derived long-chain n-alkanes, with the latter reported as weighted mean values. The two sets of δ^13C values are significantly correlated and show similar trends in spatial variation. The spatial distribution of δ^13C shows less negative values in the mid-latitudes between 31°N and 40°N and more negative ones at higher and lower latitudes. This is consistent with previously reported carbon isotope data from surface soil phytoliths in the same region and suggests that the mid-latitude area provides relatively favorable growing condi- tions for C4 plants. Furthermore, δ^13C values of both TOC and long-chain n-alkanes from 12 surface soil samples collected from a small grassland in north China displayed similar carbon isotope values and the difference between paired δ^13C of a soil samples remains relatively constant. Our data demonstrate that in eastern China, soil δ^13C composition of both TOC and long-chain n-alkanes is effective indicators of C3/C4 ratios of the prevailing vegetation. This work suggests that -22‰ and -32‰ are good es- timated end members for the weighted mean δ^13C values of long-chain n-alkanes （C27, C29 and C31 n-alkanes） from soils under dominant C4 or C3 vegetation, allowing us to reconstruct paleovegetation trends.
基金
Supported by the Knowledge Innovation Program of Chinese Academy of Sciences (Grant No.KZCX3-SW-152)
National Natural Science Foundation of China (Grant No.40331009)
the Research Foundation of the State Key Laboratory of Organic Geochemistry,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences (Grant No.OGL-200604)
the NSFC National Innovative Research Team Project (Grant No.40721061)
关键词
植物
总有机碳
碳同位素
表面土壤
surface soils, C3/C4 plants, total organic carbon, n-aikanes, carbon isotopes
