Pentachlorophenol in Quercus suber forests: An initial study in Tunisia

Persistent organic pollutants (POPs), such as organochlorine pesticides and herbicides, are a local and global environmental concern due to their recalcitrance in soils, long range transport and bioaccumulation within terrestrial & aquatic organisms and humans. Agro-forestry ecosystems are treated with a cocktail of man-made chemicals which causes soil, water and air contamination; whilst the agricultural aspect is often considered, the forest side is largely neglected due to the mistaken believe that these are non-polluted environments. A particular POP of interest is pentachlorophenol (PCP) which was widely used from the 1950s onwards as a preservative, biocide, herbicide and pesticide. Concerns raised during the 1980s regarding its health effects on humans, led to the implementation of widespread restrictions on its use. The environmental concern of PCP is increased when its many metabolic transformation products are taken into consideration, some of which are more toxic to organisms than PCP itself. Quercus suber (cork oak) forests were selected for PCP monitoring because of their local and regional economic importance. The presence of PCP fungal metabolites found on cork slabs indicates the dispersal of PCP, and its transformation products, within the oak forests. Whilst PCP fate within specific environments has been previously studied, the NATO Science for Peace project (UK, Portugal, Italy, Tunisia and Morocco) is the first to analyse PCP fate within cork forests. As part of a pilot study, soil samples were collected from Tunisian oak forests in summer 2007. Initial analysis by the UK team found that there was widespread PCP contamination; the Portuguese team focused on fungal diversity and found a decrease in diversity with increasing concentration. Future work will include the identification on non-identified species, the chemical fingerprint of contaminants present and the integration of data from all partners to allow the correlation between contamination, soil and microbiota.