Quantification of the Global Sink Removing Atmospheric CCl4 and CH3CCl3 Within Soils

本项目旨在测定大气中人为微量气体四氯化碳（CCl4）和甲基氯仿（CH3CCl3）的土壤吸收率。来自纽约长岛温带森林的数据表明，土壤是这些卤代烃的汇，因为与大气浓度相比，土壤顶层的CCl4和CH3CCl3土壤气体浓度显著降低。几种氟氯化碳的浓度在相同深度范围内保持在大气水平，这表明物理过程不是观测到的CCl4和CH3CCl3梯度的原因。来自6个主要生物群系区（耕地、温带森林、温带草原、北方森林、热带森林和热带草原以及干旱区）的土壤气体CCl4和CH3CCl3梯度测量结果将用于更好地估计这些气体进入土壤的全球通量。

The purpose of this project is to determine the soil uptake rate of atmospheric carbon tetrachloride (CCl4) and methyl chloroform (CH3CCl3), anthropogenic trace gases. Data from a temperate forest on Long Island, NY shows that soils are a sink for these halocarbons because CCl4 and CH3CCl3 soil gas concentrations were reduced significantly in the top layers of the soil as compared to the atmospheric concentration. Concentrations of several CFCs remained at atmospheric levels over the same depth range suggesting that physical processes were not responsible for the observed CCl4 and CH3CCl3 gradients. Measurements of CCl4 and CH3CCl3 gradients in soil gas from sites representative of six major biome areas (cultivated lands, temperate forests, temperate grasslands, boreal forests, tropical forests and savannas, and arid lands) will be used to obtain a better estimate of the global flux of these gases into soils.