在2010年和2011年,采集长江上游川中丘陵区万安沟小流域塘库沉积泥沙、河床沉积泥沙、不同土地利用类型的表层土壤,应用δ13C技术研究小流域土地利用变化和泥沙来源。结果表明:森林坡地、弃耕坡地和耕种梯田的表层土壤δ13C值分别是-26.40‰,-25.91‰和-25.81‰,非常相近,说明土壤有机物δ13C主要是占主导地位C3植物的残留物,而C4植物玉米对土壤有机物δ13C值几乎没有影响。结合δ13C值和土地利用变化分析,土壤和沉积泥沙δ13C值是土地利用状况的良好指示因子,较低δ13C值(-26‰)表明丘陵坡地森林覆盖率较高,而较高δ13C值(-24.30‰)则说明森林覆盖率较低。δ13C技术只有在沉积泥沙主要来源是土壤有机物的条件下,才能定量评价沉积泥沙的不同来源。由于当地沉积泥沙有机物是土壤有机物、生物碎屑和生活污水的混合物,采用δ13C指标示踪泥沙来源的可靠性受到影响,但可以肯定地说,δ13C技术对定量评价沉积泥沙的来源是有帮助的。

The δ¹³C techniques are employed to study land use changes and sediment sources in the Hilly Sichuan Basin． Some samples of pond sediments，channel bed sediments and four types of surface soils were collected in 2010 and 2011． The results show that the average δ13C values of surface soils for forest slopes，recently abandoned
cultivated sloping land and cultivated terraces are very close and they are － 26.40‰，－ 25.91‰ and － 25.81‰，respectively． Those δ₁₃C values indicate that the soil organic matter is residues of C3 plants in general，which are dominated in the natural plants of the region． Although maize is a common crop on rainfed fields in the catchment，
it has little influence on the δ13C values of the soil organic matter． By integrated analyses of the δ13C values in the sediments with the land use changes，it is suggested that δ13C values in soils and sediments are a good indicator for land use conditions． The lower values of around － 26‰ indicates good forest coverage conditions on the hillslopes in the catchment，while the higher value of around －24.30‰ indicates poor forest coverage conditions in the region． As the organic matter in the sediments is a mixture of soil organic matter，biological detritus as well as village sewages，δ13 C technique can only be used for quantitative assessment of sediment contributions from different sources under such environment conditions where the organic matter in sediments is predominately contributed from soil organic matter． However，the technique is helpful for qualitative assessment of sediment  contributions．