Pyrolysis GC–MS for the rapid environmental forensic screening of contaminated brownfield soil

Abstract

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 complex contaminated brownfield sites around the world.