北京西部活动断裂CO_(2)与Rn脱气特征及其环境影响

Degassing Characteristics of CO_(2) and Rn from the Active Fault in Western Beijing and Their Environmental Impact

利用跨断层土壤气测量方法,连续两年对北京西部黄庄—高丽营断裂、八宝山断裂和南口山前断裂CO_(2)与Rn的脱气浓度与通量进行了测量,分析了研究区断裂带脱气特征及产生的环境影响。结果表明:黄庄—高丽营断裂北段的西王路测区土壤气浓度平均值及KQ值最大,反映了该断裂北段构造活动性较强;研究区3条断裂的土壤气浓度均值及构造活动性呈现东高西低的特征,与首都圈土壤气地球化学背景场特征一致。3条断裂脱气对大气CO_(2)的年贡献量约为0.45×10^(6) t。西王路测区土壤气Rn平均浓度高于20 kBq/m^(3),其附近建筑物应采取相应的底层地面抗开裂措施,部分测点浓度高于30 kBq/m^(3)及50 kBq/m^(3),其附近建筑应采取防水处理或综合防氡措施。

The concentrations and fluxes of CO_(2) and Rn degassing from the Huangzhuang-Gaoliying fault,the Babaoshan fault and the Nankou piedmont fault in western Beijing were measured in two consecutive years using the cross-fault soil gas measurement method,and the fault degassing characteristics in the study area and their environmental impact were analyzed.The results indicated that:The average soil gas concentration and KQ value of the Xiwanglu survey area in the northern section of the Huangzhuang-Gaoliying fault are the largest,which indicated the strong tectonic activity in the northern segment of the fault.The average soil gas concentration and tectonic activity of the three faults in the study area characterized higher in the East and lower in the West which are consistent with the geochemical background characteristics of the soil gas in the capital area.The total annual output of CO_(2) from the three active fault are approximately 0.45×10^(6) t.The average concentration of Rn in soil gas in the Xiwanglu survey area is higher than 20 kBq·m^(-3),the ground floor anti-cracking measures should be taken for nearby buildings,and in some measured points which the concentration of Rn in soil gas are higher than 30 kBq·m^(-3)or 50 kBq·m^(-3),waterproof treatment or comprehensive radon prevention measures are required to prevent Rn diffusing into the buildings.