Trophic Transfer of PAHs in Terrestrial Environments Using the Spanish Slug as a Model Species

Abstract

Emissions from diesel-powered vehicles are an important source of atmospheric polycyclic aromatic hydrocarbons (PAHs). These PAHs, in turn, are easily accumulated in different vegetable species. As such, the key question of the study was whether PAHs that are already accumulated in plants can be transferred through the trophic chain, thereby affecting ecosystems. Under laboratory conditions, lettuce plants were treated with extracts of PM10 samples collected from the diesel exhaust of a light-duty vehicle. Test plants, which accumulated considerable quantities of PAHs, were used to feed Spanish slugs (Arion vulgaris L.), and PAH accumulation was measured in the slugs’ intestines. Trophic transfer, indicated by higher PAH concentrations in the slugs, was demonstrated in the case of several PAHs, both for light-molecular-weight and high-molecular-weight compounds. The concentration of total PAHs was also higher in the slug intestines compared to the concentrations found in lettuce. Measuring peroxidase (POD) levels in the slugs’ intestines revealed that accumulated PAHs induced an antioxidative response in the test animals, resulting in elevated POD concentrations.