利用有机碳同位素组成辨识土壤污染过程的方法初探

Identification of Using Organic Carbon Isotopic Composition of Soil Pollution Process

利用有机碳含量变化特征和有机碳同位素组成的变化规律,探寻土壤碳源和迁移转化过程.在北京市首钢烧结厂和通州永乐店分别采集了2条土壤剖面,对样品进行了有机碳含量和同位素组成的分析.研究结果表明,首钢工业区烧结厂和城郊土壤样品有机碳含量相差很大,表层土最高含量分别是4.4%和0.8%;首钢烧结厂附近土壤样品有机碳同位素组成仅在-24.8‰～-23.1‰之间变化,而城郊土壤样品的有机碳同位素组成在-26.4‰～-20.5‰之间变化,变化比较大.根据有机碳同位素的研究理论和方法,对比研究表明,不同土地利用方式的土壤有机质来源不同:首钢烧结厂的有机碳受到燃煤燃烧和煤炭废渣的影响,有机质含量高,污染影响可达地下70cm深处,而南郊土壤有机碳主要来自自然C3植物的枯枝落叶.两者结果虽然具有明显的差异,但是变化趋势相似,具有土壤剖面变化规律.本研究为首钢工业区环境质量评价和了解环境污染来源、污染程度和范围等问题提供了依据.

This study has taken advantage of the characteristics of concentration of soil organic matter（SOC） and δ13CSOC values to provide proofs for environment quality assessment and to know more about polluted sources,sizes and processes in Beijing steel company area.δ13C values of SOC is good for tracing sources and documenting shifts in community composition and distribution.Two sections（Beijing steel company area and Yongledian,Tongzhou） which belong to two different soil types collected in Beijing,and organic carbon isotopic composition and total soil organic carbon were analyzed.These results shows that SOC of soil samples from Beijing steel company area are quite high,and even 9.7% at the surface sample,however SOC from unpolluted area（Yongledian area） is lower than those of industrial area.δ13CSOC from soils of Beijing steel company area and Yongledian area respectively vary from-24.8‰ to-23.1‰ and-26.4‰ to-20.5‰,the results are quite different.The results reflect that there are different organic carbon sources in different types＇ soil： Organic carbon from Beijing steel company area has been mainly affected by coal burning,soil organic carbon concentrations are quite high,and pollution can affect on soils 70 cm deep underground;and soils from Yongledian area,have been not polluted,and organic matter is from natural litter（C3 plants）.Although there are different soil organic carbon concentrations and isotope compositions,two soil sections have similar variation trends.This study provides proofs for environment quality assessment and know more about polluted and natural sources,sizes in Beijing.