Environmental impact of CO2, Rn, Hg degassing from the rupture zones produced by Wenchuan M s 8.0 earthquake in western Sichuan, China

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• 作者：Xiaocheng Zhou ; Zhi Chen ; Yueju Cui
• 刊名：Environmental Geochemistry and Health
• 出版年：2016
• 出版时间：October 2016
• 年：2016
• 卷：38
• 期：5
• 页码：1067-1082
• 全文大小：2,105 KB
• 刊物类别：Earth and Environmental Science
• 刊物主题：Earth sciences
  Geochemistry
  Atmospheric Protection, Air Quality Control and Air Pollution
  Public Health
  
• 出版者：Springer Netherlands
• ISSN：1573-2983
• 卷排序：38

文摘

The concentrations and flux of CO₂, 222Radon (Rn), and gaseous elemental mercury (Hg) in soil gas were investigated based on the field measurements in June 2010 at ten sites along the seismic rupture zones produced by the May 12, 2008, Wenchuan M_s 8.0 earthquake in order to assess the environmental impact of degassing of CO₂, Rn and Hg. Soil gas concentrations of 344 sampling points were obtained. Seventy measurements of CO₂, Rn and Hg flux by the static accumulation chamber method were performed. The results of risk assessment of CO₂, Rn and Hg concentration in soil gas showed that (1) the concentration of CO₂ in the epicenter of Wenchuan M_s 8.0 earthquake and north end of seismic ruptures had low risk of asphyxia; (2) the concentrations of Rn in the north segment of seismic ruptures had high levels of radon, Maximum was up to level 4, according to Chinese code (GB 50325-2001); (3) the average geoaccumulation index I_geo of soil Hg denoted the lack of soil contamination, and maximum values classified the soil gas as moderately to strongly polluted in the epicenter. The investigation of soil gas CO₂, Rn and Hg degassing rate indicated that (1) the CO₂ in soil gas was characterized by a mean \(\updelta^{13}C_{CO2}\) of −20.4 ‰ and by a mean CO₂ flux of 88.1 g m−2 day−1, which were in the range of the typical values for biologic CO₂ degassing. The maximum of soil CO₂ flux reached values of 399 g m−2 day−1 in the epicenter; (2) the soil Rn had higher exhalation in the north segment of seismic ruptures, the maximum reached value of 1976 m Bq m−2 s−1; (3) the soil Hg flux was lower, ranging from −2.5 to 18.7 n g m−2 h−1 and increased from south to north. The mean flux over the all profiles was 4.2 n g m−2 h−1. The total output of CO₂ and Hg degassing estimated along seismic ruptures for a survey area of 18.17 km2 were approximately 0.57 Mt year−1 and 688.19 g year−1. It is recommended that land-use planners should incorporate soil gas and/or gas flux measurements in the environmental assessment of areas of possible risk. A survey of all houses along seismic ruptures is advised as structural measures to prevent the ingress of soil gases, including CO₂ and Rn, were needed in some houses.KeywordsSoil gasFluxEnvironmental impactRuptureCO₂RnHgWenchuan earthquake