Using Tree Core Samples to Monitor Natural Attenuation and Plume Distribution After a PCE Spill

Abstract

The potential of using tree core samples to detect and monitor natural attenuation of perchloroethene (PCE) in groundwater was investigated at a PCE-contaminated site. In the area of the known plume with PCE concentrations between 0.004 and > 40 mg/L, cores were collected from tree trunks at a height of about 1 m above ground surface. Tree sampling of the site was completed in under six hours. Chlorinated ethenes were analyzed by headspace GC/MS. PCE (0.001 to 7 mg/ kg) and natural attenuation products, TCE (< 0.001 to 0.4 mg/ kg) and c-DCE (< 0.001 to 0.46 mg/kg), were detected in tree cores. 1,1-dichloroethene and vinyl chloride were not detected, corresponding to very low concentrations in the groundwater. The contaminant plume was mapped from the concentrations measured in trees, which delineated a probable hot spot area that had been undetected in decades of traditional groundwater monitoring. Natural attenuation products in tree cores increased with distance from the known source area. Concentrations of PCE and reductive dechlorination products in tree cores were correlated with the corresponding groundwater concentrations. Within a range of limitations, tree-core sampling provides a rapid, reliable and inexpensive method to investigate the extent of shallow contamination by chlorinated ethenes in soil and groundwater.

Phytoscreening and phytoextraction of heavy metals at Danish polluted sites using willow and poplar trees

“…Today, phytoscreening of soil and groundwater has become a scientifically validated and recognized method (Sorek et al 2008; Gopalakrishnan et al 2007) and has frequently been used to investigate plumes of chlorinated solvents, such as tetrachloroethene, trichloroethene, and cis-1,2-dichloroethene (Sorek et al 2008; Larsen et al 2008). The principle underlying the method is that contaminants are taken up by roots and translocated upwards to the stem.…”

Use of Dendrochronology and Dendrochemistry in Environmental Forensics: Does It Meet theDaubertCriteria?

“…For example, tree-ring studies have been used to monitor areas contaminated with arsenic (Cheng et al, 2007); fossil fuels (Baes III and Ragsdale, 1981;Balouet and Oudijk, 2006;Balouet et al, 2007;Balouet et al, 2008), heavy metals (Zou et al, 2004;Punshon et al, 2005;Devall et al, 2006;Sheppard et al, 2007), chlorinated solvents (Balouet et al, 2007;Larsen et al, 2008), nutrients (Vroblesky and Yanosky, 1990;Vroblesky et al, 1992), precipitation acidity (Kwak et al, 2008), and radioactive isotopes (Edmunds et al, 2001;Kalin, 1995;Kagawa et al, 2002;Mazeika et al, 2007;Rao et al, 2002). Tree-core studies also have been used to map the subsurface distribution of contamination by chlorinated solvents (Vroblesky et al, 1999;Schumacher et al, 2004;Vroblesky et al, 2004;Doucette et al, 2007;Graber and Soprek, 2007).…”

ModelPROBE: model driven soil probing, site assessment and evaluation

“…The highest potential for cost reduction due to non-invasive site assessment resides with geophysical techniques or tree monitoring (Larsen et al 2008). These methods need to be standardised and evaluated against conventional methods.…”

“…However, polar persistent chemicals are well known to be translocated from soil through roots to stem and leaves of plants (Trapp et al 2007). Sampling of wood and/or other vegetation parts can therefore be used to detect and monitor subsurface pollutants and natural attenuation processes (Larsen et al 2008). Plant analyses thus provide a very cost-effective tool for site screening and monitoring and will be applied in ModelPROBE.…”