Using membrane interface probe (MIP) to characterize chlorinated volatile organic compounds in glacial sediments.

摘要

A Membrane Interface Probe (MIP) with an electron capture detector (ECD) and photo ionization detector (PID) was used to characterize chlorinated volatile organic compounds (CVOCs) in soils at a drycleaner located in the glaciated Appalachian Plateau Province of northeastern Pennsylvania. Characterizing CVOCs in glacial till requires extensive horizontal and high resolution vertical delineation due to subsurface heterogeneity. The MIP technology provides real-time data in the field which allow for flexibility in sampling plans and optimization of time in the field, both of which are distinct advantages over traditional discrete soil sampling. MIP data are not absolute; confirmation sampling is required. Trend analysis of the ECD responses within the identified ECD response range and laboratory analyses of confirmation samples produced an R2= 0.89. A similar PID trend analysis produced an R 2= 0.75. Conductivity readings matched confirmation core lithology interpretations 75% of the time; temperature correlated with the presence of groundwater 69% of the time. The MIP provided relatively high resolution (0.3m intervals) vertical soil characterization data, and combined with the confirmation cores, the data allowed for optimum placement and screening of monitoring wells. The resulting groundwater data, combined with the MIP data, provided a comprehensive site characterization. The effectiveness of MIP as a site characterization tool is directly related to the field team's experience with MIP and the availability of historic MIP field data.