Subsurface Airflow Induced by Natural Forcings

Subsurface air flow can be induced by natural processes, such as atmospheric or barometric pressure changes, water table fluctuations, topographic effects, and rainfall infiltration. Barometric pressure fluctuations are the most common cause of subsurface air flow, which can be significant under favourable geological conditions. This process has been studied most extensively because of its application to passive soil vapor extraction. Soil air flow induced by water table fluctuations can be significant, particularly where the fluctuations are of high frequency, for example, in tidal-influenced coastal areas. Topographic effects can lead to strong subsoil air flow in areas with great elevation differences. Rainfall infiltration usually produces only weak airflow. Air flow induced by these natural processes has important environmental and engineering implications. Among the different processes, air flow induced by tidal fluctuations has been studied the least, although it has exciting applications to coastal engineering projects and environmental remediation.

On the Lucas Base and Computation of Counting Function Mean Value

In this paper, we introduce a new counting function a(m) related to the

纳米硫化锌吸附剂中汞的稳定性研究

为了探究对纳米硫化锌吸附剂中汞的稳定性,采用重金属污染评价方法毒性特性浸出(TCLP)法对纳米硫化锌(Nano-ZnS)吸附的汞稳定性进行评价,并进一步研究了纳米硫化锌汞吸附量、浸提剂初始pH、浸出时间、液固比以及酸雨类型等对纳米硫化锌中汞稳定性的影响.结果表明:在偏酸性与偏碱性的条件下浸出液汞浓度较大,但是即使在pH=1与pH=13的情况下纳米硫化锌吸附的汞最大浸出浓度也仅分别为0.292μg/L与4.211μg/L。同时TCLP实验结果远低于TCLP标准中汞的安全浓度值25μg/L,说明纳米硫化锌吸附的汞具有良好的稳定性。