Author's personal copy Bioaccessibility, bioavailability and ecotoxicity of pentachlorophenol in compost amended soils Edoardo Puglisi a , Pasqua Vernile b , Giuseppe Bari b , Matteo Spagnuolo b , Marco Trevisan a, * , Enrico de Lillo b , Pacifico Ruggiero b a Istituto di Chimica Agraria ed Ambientale, Università Cattolica del Sacro Cuore, Via Emilia Parmense 84, 29100 Piacenza, Italy b Dipartimento di Biologia e Chimica Agroforestale ed Ambientale, Università di Bari, Via Amendola 165/A, 70126 Bari, Italy article info Article history: Received 18 March 2009 Received in revised form 12 May 2009 Accepted 15 May 2009 Available online 17 June 2009 Keywords: Aging Degradation Nonexhaustive extraction techniques Remediation Biosensors Earthworms abstract The influence of compost on the bioaccessibility, bioavailability and ecotoxicity of pentachlorophenol (PCP) as a function of time was studied by means of different chemical and ecotoxicological methods. Experiments were conducted in both sterile and non-sterile microcosms and samplings carried out at 20, 60 and 120 d from initial contamination. PCP bioaccessibility, assessed by means of Porapak resin extraction, was around 75% of the applied dose with no aging or compost effects. Two different methods were applied to assess the bioavailability of PCP, respectively, to bacteria and earthworms and linked to ecotoxicological assays (biosensor and earthworm coelomocytes assays). Water extraction was applied to assess the bioavailability to bacteria: results showed that this fraction was always below 50%, with significant decreases as a result of aging processes and compost addition. In non-sterile microcosms, compost amendment increased the amount of PCP bio- degraded, while the ecotoxicological assay with the biosensor Pseudomonas fluorescens pUCD607 indi- cated a higher toxicity in the most degraded samples, thus suggesting the formation of more toxic metabolites. Earthworm body accumulation results were rather in accordance with water extractions data, with decreasing bioavailable amounts as a result of time and compost addition. No compost or aging effects were instead detected by coelomocytes assay. Results indicate how different methods must be applied altogether to assess the bioavailability and ecotoxicity of xenobiotics such as PCP in soil. The addition of compost was also proven as an effective strategy for the remediation of PCP contaminated soils, although issues related to the possible formation of toxic metabolites must be taken into account. Ó 2009 Elsevier Ltd. All rights reserved. 1. Introduction Pentachlorophenol (PCP) is a broad-spectrum biocide firstly introduced in the 1920s. PCP is a widespread environmental con- taminant of soil, surface water and groundwater: it is known to bioaccumulate, to be very toxic and it is classified in the priority list of organic micropollutants because of its carcinogenity and tox- icity (Reigner et al., 1993; ATSDR, 2001) PCP utilization as a pesti- cide is widely forbidden, but many countries still use it to prevent fungal attacks on wood (Jenson, 1996). When organic contaminants such as PCP enter the soil environ- ment they are subjected to a number of processes. A contaminant may be lost at different rates and to different extents through vol- atilization, leaching and degradation (Stokes et al., 2006). The frac- tion remaining in the soil is not completely available to living organisms, because part of it is progressively sequestrated by or- ganic and inorganic constituents, and thus less available to micro- bial attack. Many different and sometimes contrasting definitions have been used to describe this bioavailable fraction of contami- nants in soils. A distinction has been recently made between the bioavailable and the bioaccessible fractions of contaminants: bio- available is the fraction ‘‘which is freely available to cross an organ- ism’s cellular membrane from the medium the organism inhabits at a different time”, while bioaccessible is the one ‘‘which is avail- able to cross an organism’s cellular membrane from the environ- ment if the organism has access to the chemical” (Semple et al., 2004). Bioavailability can be specific to organism and even partic- ular species (Stokes et al., 2006), and it is strongly influenced by ac- tual rates of give (dissolution, desorption and diffusion) and take (degradation), while the bioaccessible fraction may be a relatively defined and robust quantity representing a promising target for the development of chemical proxies (Semple et al., 2007). Different methods can be used to extract the above defined bio- available and bioaccessible fraction of contaminants; choice of the appropriate methods must also be based on the molecule studied. 0045-6535/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.chemosphere.2009.05.022 * Corresponding author. Tel.: +39 0523 599 218; fax: +39 0523 500 217. E-mail address: marco.trevisan@unicatt.it (M. Trevisan). Chemosphere 77 (2009) 80–86 Contents lists available at ScienceDirect Chemosphere journal homepage: www.elsevier.com/locate/chemosphere