The complex spatial distribution of trichloroethene and the probability of NAPL occurrence in the rock matrix of a mudstone aquifer

Journal of Contaminant Hydrology
By: , and 

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Abstract

Methanol extractions for chloroethene analyses are conducted on rock samples from seven closely spaced coreholes in a mudstone aquifer that was subject to releases of the nonaqueous phase liquid (NAPL) form of trichloroethene (TCE) between the 1950's and 1990's. Although TCE concentration in the rock matrix over the length of coreholes is dictated by proximity to subhorizontal bedding planefractures, elevated TCE concentrations in the rock matrix are not continuous along the most permeable bedding plane fractures. A complex configuration of subvertical and subhorizontal fractures appears to be responsible for the TCE distribution from prior TCE releases at land surface. Phase partitioning calculations of TCE in the rock matrix show that most TCE is adsorbed to solid surfaces because of the large fraction of organic carbon (foc) in the mudstone. Large TCE content in some cores indicate the likely presence of the NAPL form of TCE in the rock matrix. Using average values of porosity (n) and foc in phase partitioning calculations identifies a number of locations of possible NAPL occurrence in the rock matrix. Samples of mudstone analyzed for n and foc show variability in these properties over several orders of magnitude. Accounting for this variability in phase partitioning calculations identifies a probability of NAPL occurrence, PNAPL. The spatial variability of PNAPL along coreholes identifies a configuration that may be attributed to a TCE source zone that has evolved after emplacement due to NAPL dissolution, adsorption, and matrix diffusion.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title The complex spatial distribution of trichloroethene and the probability of NAPL occurrence in the rock matrix of a mudstone aquifer
Series title Journal of Contaminant Hydrology
DOI 10.1016/j.jconhyd.2019.04.001
Volume 233
Year Published 2019
Language English
Publisher Elsevier
Contributing office(s) National Research Program - Eastern Branch, National Research Program - Western Branch, Maryland Water Science Center, Pennsylvania Water Science Center, New Jersey Water Science Center, WMA - Earth System Processes Division
Description 103478; 14 p.
Country United States
State New Jersey
City West Trenton
Other Geospatial Newark Basin