西安市城区表层土壤碳储量与分布特征

目的]研究城市的土壤碳储量与分布特征,为进一步认识城市碳固定和碳循环提供科学依据。方法]采集西安市绕城高速内不同土地利用/功能区表层土壤样品230个(0—20cm),利用Vario ELⅢ元素分析仪进行有机碳分析。结果]西安市城区表层土壤有机碳在0.88~27.18g/kg之间,均值为5.59g/kg;碳密度0.22~7.11kg/m2,均值为1.41kg/m2;在西安市城区表层土壤总储碳量为6.32×105 t,平均每1km2的土壤碳储量为1.37×103 t。风景休闲区和交通区是城区土壤有机碳含量较高的区域,而工业区有机碳含量较低。在空间上,以中心城区形成一个南北带状分布的有机碳高值区。结论]西安市城区的这种有机碳分布模式,与城市化前的土壤利用、城市绿地管理,食物与燃料的残余物、各种废水等大量生活垃圾进入土壤有关。交通道路的有机碳含量也受到汽车尾气排放的黑炭沉降影响。整体上,西安市城区有机碳显著低于国内其它城市的有机碳含量。

Surface Soil Carbon Storage and Distribution in Xi'an City

Objective] With the development of urbanization,a large number of natural lands or agricultural lands are changed into urban land,which bring about dramatic changes in soil carbon stocks.It has an impor tant significance for understanding of urban soil carbon pools and the response to global change to research the soil carbon storage in city area.Methods] The inner Xi'an beltway area was selected as research range,where the soil carbon pool was researched.Total 230 surface soil samples under different land uses/functions were collected,and soil organic carbon of each sample was analyzed by Vario ELⅢ elementer.Results] The soil organic carbon ranged 0.88～27.18 g/kg with a mean of 5.59 g/kg;and the organic carbon density was 0.22～7.11 kg/m2 with a mean of 1.41 kg/m2.The total carbon storage was 6.32× 105 t in the city area of inner Xi'an beltway,the average per square kilometer was 1.37 × 103 t.The scenic recreation and traffic area were the regions with high soil organic carbon content,and the industrial zone was relatively lower.A northsouth strip of high soil organic carbon with city center as concentrated core was recognized.Conclusion] The soil organic carbon distribution pattern of Xi'an City maybe relate to some indices prior to urbanization,as soil use,green management,garbage of food and fuel residues and waste water into the soil.The organic carbon content near traffic road was affected by black carbon settlement from vehicle exhaust emissions.The overall topsoil organic carbon content of Xi'an urban was significantly lower than that of other domestic cities.