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Organic Geochemistry


An abandoned chemical plant in Asturias (Spain) was studied using a multi-faceted molecular fingerprinting approach, demonstrating that it is possible to: (1) carefully unravel tangled evidence resulting from multiple pollution sources, and (2) recognize major contaminants largely ignored by conventional analyses. This methodology employed a battery of GC-MS analyses of liquid chromatographic fractions of soil extracts, plus the pyrolysis products of the soil extract's asphaltene fraction and the whole soil itself. In this example, coal tar distillation and the subsequent production of naphthalene, phenols and polymer resins are responsible for most of the soil contamination. Styrene, naphthalene, indene, and their methylated derivatives and dimers (most notably, naphthyl-methylnaphthalene) are particularly abundant and/or distinctive. It is remarkable that most of the contaminants were detected simply by pyrolysis-GC-MS, demonstrating its effectiveness for rapid environmental forensic screening of organic contamination. Commonly used environmental analytical approaches would likely have overlooked the predominant pollutants at this site. This could lead to serious shortcomings in remediation planning and implementation. The novel methodology presented herein appears practical and applicable to complexly-contaminated brownfield sites around the world.


The site discussed in this paper exemplifies the complex legacy of contamination afflicting many brownfield zones in industrialized countries. The multi-faceted environmental forensic approach to molecular fingerprinting documented herein demonstrates that it is possible to carefully unravel tangled evidence resulting from multiple soil pollution sources, and recognize major contaminants ignored by conventional analytical procedures and overlooked by current environmental regulations. It seems self-evident that this approach would foster more effective site remediation procedures.

Specifically, LC fractionation was revealed to be a very useful tool for separation of complex mixtures of legacy contaminants in order to perform full-scan GC-MS identifications, much more powerful for forensic purposes than usual quantitative techniques. As a rapid alternative, Py-GC-MS, which require only minimal sample preparation, was sufficient to identify the majority of the contaminants present at the site, and therefore is very useful as a screening system to quickly obtain qualitative results in soil pollution studies.


Published Citation

Lara-Gonzalo A., Kruge M.A., Lores I., Gutiérrez B., Gallego J.L.R. (2015) Pyrolysis-GC-MS for the rapid environmental forensic screening of contaminated brownfield soil. Organic Geochemistry 87:9-20.