城市化过程中黑碳的土壤记录及其环境指示意义

以南京市为对象,通过3组共计10个土壤剖面的采样,用湿化学氧化法分析了土壤有机碳（organic carbon,OC）和黑碳（black carbon,BC）的含量.研究发现,南京城市土壤剖面中黑碳含量的变幅为0.22～32.19 g·kg^-1,平均值为4.35 g·kg^-1.第1组城市土壤剖面中黑碳含量的平均值为0.91 g·kg^-1,第2组为8.62 g·kg^-1,第3组为3.72 g·kg^-1.城市土壤剖面中BC/OC值的变幅为0.03～1.59,平均值为0.29,其中BC/OC平均值的大小顺序是：受古代工业活动影响的第2组最大,受现代工业和交通人为活动影响的第3组次之,受古代居民生活影响的第1组最低.研究认为,在城市化过程中,由于工业和交通等人类活动引起的生物物质和矿物燃料（煤、石油等）燃烧产生的BC在土壤中都有不同程度的沉积和记录.BC含量和BC/OC值的大小可能在一定程度上反映了不同人为影响过程和城市土壤的污染程度.城市区域BC的主要来源是矿物燃料燃烧,其中表层（现代层）主要来自交通车辆（尤其是柴油为动力的机车）排放的颗粒物质,而在古代（文化层）可能与燃烧用煤历史有关.

Soil Record of Black Carbon During Urbanization and Its Environmental Implications

This investigation selected the city of Nanjing, Jiangsu province of China, as the study area, and analyzed the concentrations of organic carbon (OC) and black carbon (BC) of ten soils profiles in three different groups, by wet chemical oxidation methods. The results showed that the concentration of BC ranged from 0.22 g x kg(-1) to 32.19 g x kg(-1) in all urban soil profiles, and the average concentration of BC reached 4.35 g x kg(-1). The average concentration of BC of the first group from ancient residential areas was 0.91 g x kg(-1), and that of the second group affected by ancient industrial activities was 8.62 g x kg(-1), the third group influenced by the modern industrial and traffic emission was 3.72 g x kg(-1). The ratio of BC/OC ranged from 0.03 to 1.59 in all profiles, and the average was 0.29. The average ratio of BC/OC of three groups appeared in this order: the highest exists in the second group, followed by the third group, and the last is the first group. These data mean that some BC particles produced by local biomass and/or fossil fuel burning due to the industrial and transport activities during urbanization are recorded in soils. In addition, the contents of BC and the ratio of BC/OC may reflect different processes of human activities and pollution intensities of urban soils. It is concluded that the soil BC in urban area is mainly coming from fossil fuel burning, more specifically, BC in surface layer (present layer) is mainly from the exhaust particles of motor vehicles (especially diesel engine), while in ancient layer (cultural layer) it is possibly related to the historical coal use.