Pollution Investigation by Trees (PIT)

Submitted by: Chris Balouet on behalf of the PIT-team, email JCBalouet@aol.com

Pollution Investigation by Trees (PIT) is an International research program funded by the French Agency of Environment and Energy Management (ADEME) to develop the use of phytoscreening and dendrochemical applications at polluted sites. A first overview of the methods was presented at Nicole in June 2011.

Abstract :

Phytoscreening is the use of plants to characterize polluted sites, using microsamples of trees’s outermost rings. Because roots do uptake contaminants from groundwater, soils and soil gases, as an integral of its rootball exposures. Sap transported contaminants are sampled with non invasive tools, analysed with conventional methods, including GC MS for the organics, or ICP/MS versus EDXRF, though at much lower detection limits, most often by the ppt, as allowed by modern lab equipment. Phytoscreening allows, within minimum time and costs, to semi-quantatively delineate and map plumes. Although such delineation and mapping reflects contaminant distribution, it is used as reconnaissance level, phase I, not replacing phase II where underground contamination needs to be exactly quantified.

Further on, since trees uptake represents an integral of their exposures from groundwater, soil and soil gases, one analysis by tree is enough, rather than multiple samples at different depths.

Dendrochemistry, or the chemistry of tree rings, relays on small cores, 1 cm in diameter, to document past environmental impacts at trees’ stands, over as many ring years as the trees and the cores allow. Prime benefit of dendrochemistry is to age-date past environmental impacts, and thus reconstruct site’s environmental history, including asynchronous releases, calculate effective plume migration, as is important in complex cases, including for litigation purposes.

Prime interest of these methods is that they are :

• fast, as a one km long plume, based on 50 locations can be sampled in one day, • cheap, as only one analysis per location is needed, whilst avoiding expensive wells. • non invasive, allowing access to “difficult” sites, and without nuisance, with minimal

environmental impact, no global warming gases nor important water volumes needed.

Started late 2010, program completion is due mid 2013, PIT will investigate 21 sites in Europe and the USA. Pollutants such as HVOCs, fossil fuels, PAH, heavy metals, PCBs and Dioxins are being tested. As an international research effort, PIT is joined by 22 members* representing governmental organizations, universities, laboratories and private companies who uses the above methods, from 7 different countries.

The program and the team:

This important research program is further aimed at promoting the methods, to the benefit of the environment and parties who serve polluted sites. Two methodical guides are being worked out for publication in 2013.

PIT’s user members, Environment International, HPC Envirotec, SevequeEnvironnement, Cabinet ConseilBlondel, Exponent and Triassic Technology, who have recently positively used the methods, hereby apply to the Nicole awards, with the promotion of PIT’s methods, team, and applications in mind. Funding, if any, would support the diffusion of methodical guides awaited next year.

• Governmental organizations : USGS, Dr Don Vroblesky, Dr John Schumacher ; USDA Forestry Services : Dr Kevin Smith , Dr Walter Shortle; Volcani Center Israel, Dr Ellen Graber; ADEME, Dr Hélène Roussel;INRA, DrStéphanePonton , Dr François Beaujard.

• Universities : University of Sciences and Technology, Rolla, Prof. Joel Burken ; Université de Franche-Comté, UMR6249, UFR Sciences et techniques, LaboratoireChronoEnvironnement , Prof. Michel Chalot ; University of Stockholm, DrHakanGrudd; Royal Military College Ontario, Prof. Barbara Zeeb; Univeristy of Strathclyde, Dr Caroline Gauchotte.

• Laboratories :CebamAnalyticals , DrLian Liang; Wessling ; Cox Analyticals, Anders Rindby. • Consulting firms : Dr Chris Balouet, Environment International ; Dr Jean Louis Sevèque,

Sevèque Environnement ; Dr Frank Karg, HPC Envirotec; Dr Thierry Blondel, Cabinet Conseil Blondel ; Gary Bigham, Exponent ; Gil Oudijk, Triassic Technologies.

PIT and Phytoforensics methods

Trees do uptake contaminants to which their rootballs are exposed, as an integral of the groundwater, soil and soil gases (GW ∫ Soil ) impacts.

These contaminants are translocated by sap, and microsamples made from the wood are enough to document current exposure of the tree to underground contaminants.

Further on, since new wood is formed annually as rings, contaminants are fixed in new cells, analytical line scanning over cores allows to document their appearance,

like in a black box, and thus age date impact times.The methods are non invasive, fast and cheap.

Sampling tools and Analytical methods

Sampling tools for phytoscreening: sampling hammer for VOCs, auger bit for non volatiles.

Analytical methods used in phytoscreening are primarily GC MS, including GC ECD or GCFID for volatiles, headspace. When coupled to SPME, they allow for measuring simultaneously different organics, by the ppt level.

PIT is currently testing GC GC / MS for PCBs and Dioxins.

Sampling tools for dendrochemistry :Pressler borer, 10 mm diameter.

Dendrochemical analysis is typically performed by EDXRF linescanning.

Phytoscreening: some case studies

This case was developed & operated by the R&D-Division of HPC Group & HPC Envirotec SA under Frank KARG and Chris Balouet, Environment International.

Published in : Limmer, M. A.; Balouet, J. C.; Karg, F.; Vroblesky, D. A.; Burken, J. G., Phytoscreening for

Chlorinated Solvents Using Rapid in Vitro SPME Sampling: Application to Urban Plume in Verl, Germany. Environmental Science & Technology 2011,45, (19), 8276-8282.

This case deals with a Citychlor site. 5 trees were sampled within 2 hours. Samples were made for each tree, to the N, E, S and W. Above centrogram for one tree, shows concentrations for PCE, TCE and cDCE. Since root direction influences uptake, the cardinal centrogram, and associated centroids shows the relative cardinal distribution by the tree.

Hereby tree 3 is above hot spot. Combining the evidence from the 5 trees allows to identify groundwaterand plume migration directions, establish limited bio-attenuation…

This case was developed by Environment International

This case was selected to check on trees capacity to document deep groundwater contamination. Whilst phytoscreening methods efficiently tested for groundwater depth less than 10 m, it is 35 m deep in this case, with minimum soil contamination. However, abundant gas phase, under current analytical consolidation, could significantly contribute for uptake in this case.

In this case, phytoscreening allows to distinguish two distinct plumes.

This case was developed by SevèqueEnvironnement and Environnement International.

In this case, 3 distinct plumes for PCE, Benzene and Toluene can be identified, and mapped. A case developed by Cabinet ConseilBlondel and Environment International.

Other phytoscreening applicationsbeing tested by PIT are towards metals, PAH,

PCBs and dioxins.

State of the art methods are used for organics, including SPME. Soon will start analysis of PAH, PCBs and Dioxins using most performant GC GC MS equipment.

ICP/MS is used for sought metals (Cd, Cr, Cu, Ni, Pb, Zn).

For Hg, almost 200 samples from a US Superfund site and France have been analyzed by Combustion Trap Cold Vapor Atomic Fluorescence Spectroscopy (CVAFS) by Cebam Analytical Inc., at a detection limit of 0.1 ug/g. Resulting data allows to establish background mercury in tree cores less than 5ng/g, establish uptake by tree roots. Many of the samples went to isolated rings of old tree cores, to determine past site history. PIT’s mercury investigation is run by Gary Bigham of Exponent and by Environment Internationa, along with other PIT experts.

Dendrochemistry : PIT is working on 55 cores, from 22 sites, providing an estimated set of 2500 rings and 7 million EDXRF data.

Chlorinated Solvents in Verl.

EDXRF data allows to use Chlorine as tracer for past impacts by chlorinated solvents. 31 elements are jointly analysed, allowing to discriminate pollutants, other environmental and physiological events.

Verl case was also investigated by phytoscreening methods (see above).

The four dendrochemicallyanalyzed trees allowed to identify 5 asynchronous releases, correlate plume impacts, quantify plume migration rate and age date releases at source.

This case was developed & operated by the R&D-Division of HPC Group & HPC Envirotec SA under Frank KARG and Chris Balouet, Environment International.

Above phytoscreening and dendrochemical cases “prove that the innovative Phyto-screening and Dendro-chemical approach can be applied commercially in application”*.

The hereby application to NICOLE’s award is submitted by “users group”, in name of the international program and its whole and fully dedicated team.

*Email by Frank Karg, dated April 24, 2012.