Search

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jenvman.2005.07.005 Byline: Tessa Mills (a), Barbara Arnold (a), Siva Sivakumaran (a), Grant Northcott (b), Iris Vogeler (a), Brett Robinson (a), Cara Norling (a), Doris Leonil (c) Abstract: Pentachlorophenol (PCP) is a persistent organic pollutant (POP) previously used as a timber treatment chemical to prevent sap stain and wood rot. Commonly used in wood treatment industries for the last 50 years, there are now many sites worldwide that are contaminated with PCP. Although persistent, PCP is a mobile contaminant and therefore has a propensity to leach and contaminate surrounding environments. Both willow (Salix sp., 'Tangoio') and poplar (Populus sp. 'Kawa') growing in an open-ended plastic greenhouse were found to tolerate soil PCP concentrations of 250mgkg.sup.-1 or less and both species stimulated a significant increase in soil microbial activity when compared to unplanted controls. Both poplar and willow could not survive PCP concentrations above 250mgkg.sup.-1 in soil. Pentachlorophenol degradation occurred in both planted and unplanted pots, but a higher rate of degradation was observed in the planted pots. Soil contaminated by wood-treatment activities often contains co-contaminants such as B, Cr, Cu and As, that are also used as timber preservatives. An additional column leaching experiment, done along side the potted trial, found that PCP, B, Cr, Cu and As were all present in the column leachate. This indicates that although Cu, Cr and As are generally considered immobile in the soil, they were mobilised under our column conditions. If a contaminated site were to be hydraulically 'sealed' using plants, a reticulation irrigation system should be installed to capture any contaminant leachate resulting from heavy rains. This captured leachate can either be independently treated, or reapplied to the site. Our data demonstrate a reduction in soil hydraulic conductivity with repeated application of leachate containing PCP and metal compounds but the soil did not become anaerobic. This would need to be considered in site remediation design. Author Affiliation: (a) HortResearch, Sustainable Landuse Group, Private Bag 11030, Palmerston North, New Zealand (b) HortResearch, Ruakura Research Centre, Private Bag 3123, Hamilton, NZ (c) Universite de la Reunion, Maitrise sciences et techniques,Valorisation chimique et biologique du vegetal, Campus du Moufia, 15 avenue Rene Cassin, BP 7151-97 715 Saint-Denis messag cedex 9, France Article History: Received 16 December 2004; Revised 14 May 2005; Accepted 18 July 2005