Evaluation and in situ assessment of photodegradation of polyaromatic hydrocarbons in semipermeable membrane devices deployed in ocean water Tatiana V. Komarova a, * , Michael E. Bartkow a , Sibylle Rutishauser b , Steve Carter c , Jochen F. Mueller a a The University of Queensland, National Research Centre for Environmental Toxicology (EnTox), 39 Kessels Road, Coopers Plains, Queensland, Australia b Swiss Federal Institute of Aquatic Science and Technology (Eawag), Department of Environmental Toxicology, CH-8600 Du ¨bendorf, Switzerland c Queensland Health Forensic and Scientific Service (QHFSS), Queensland, Australia Our study indicates that photodegradation of PAHs occurs from passive water samplers (SPMDs) deployed in different devices. article info Article history: Received 3 July 2008 Received in revised form 11 November 2008 Accepted 19 November 2008 Keywords: Performance reference compounds Photodegradation Semipermeable membrane devices abstract Semipermeable membrane devices (SPMDs) were deployed in water using four different methods: a typical SPMD cage with and without a mesh cover, a bowl chamber and without any protection. In addition to routinely used performance reference compounds (PRCs), perdeuterated dibenz[a,h]anthracene was added. Due to its high sampler to water partition coefficient no measurable clearance due to diffusion was expected during the deployment period, hence any observed loss could be attributed to photodegradation. The loss of PRCs was measured and SPMD-based water concentrations determined. Results showed that a typical SPMD deployment cage covered with mesh provided the best protection from photodegradation. Samplers which had undergone the highest photodegradation underestimated PAH water concentrations by up to a factor of 5 compared to the most protected SPMDs. This study demonstrates that the potential for photodegradation needs to be addressed when samplers are deployed in water of low turbidity. Ó 2008 Elsevier Ltd. All rights reserved. 1. Introduction Passive samplers are a useful tool for monitoring non-polar contaminants such as polyaromatic hydrocarbons (PAHs) and various pesticides in the aquatic environment. A range of abiotic samplers have been developed to monitor these chemicals in water, however the semipermeable membrane device (SPMD) is currently the most commonly used (Gustavson and Harkin, 2000; Luellen and Shea, 2002; Verweij et al., 2004; Huckins et al., 2006). PAHs are a group of organic compounds that includes some potent carcinogens. PAHs originate from many sources including combustion processes such as motor vehicles. They are commonly found in urban runoff in which they are transported via surface runoff and stormwater discharge into the aquatic environment. PAHs are potentially harmful in aquatic systems at the nanogram and subnanogram per liter levels (DHHS, 2005). However, most routine analytical methods have limits of detections above these concentrations. Passive samplers such as SPMDs are deployed in the water column for several weeks and can accumulate pollutants allowing monitoring of PAHs at subnanogram per liter levels in aquatic environments. These samplers have the added advantage of simulating accumulation that occurs in aquatic biota. Furthermore this technique measures the time integrated water concentration of dissolved organic pollutants in contrast to grab sampling tech- niques which only represent single points in time. Chemical exchange between a passive sampler and the water can be affected by environmental factors such as flow, temperature and biofouling. In order to account for the effects of these factors, performance reference compounds (PRCs) have been developed (Huckins et al., 2002a,b). These chemicals are added to the sampler prior to deployment. The concept behind the PRC approach is that the overall uptake and elimination rates of hydrophobic organic compounds in SPMDs are governed by first-order kinetics and that residue exchange with the sampled medium is isotropic. To use this approach, the investigator must be sure that the PRCs do not occur in the environment (certain non-labeled or native compounds such as PCB congeners 14, 29, 50 and a variety of compounds labeled with deuterium (D), 13 C or 14 C generally can be used) and the desorption of the compound from the sampler during the given deployment period needs to be greater than 20%, but not exceed 80% of its original mass. PRC dissipation is described by the following equation: N ¼ N 0 expð k e tÞ (1) where N 0 is the amount present at t ¼ 0. If N and N 0 are measured, the PRC elimination (or loss) rate constant (k e ) can be estimated (Huckins et al., 2006). * Corresponding author. Tel.: þ61 7 3274 9120; fax: þ61 7 3274 9003. E-mail address: t.komarova@uq.edu.au (T.V. Komarova). Contents lists available at ScienceDirect Environmental Pollution journal homepage: www.elsevier.com/locate/envpol 0269-7491/$ – see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.envpol.2008.11.040 Environmental Pollution 157 (2009) 731–736