, Volume 10, Issue 2, pp 162-171
Date: 19 Nov 2009

Freely dissolved PCDD/F concentrations in the Frierfjord, Norway: comparing equilibrium passive sampling with “active” water sampling

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Abstract

Introduction

Equilibrium passive samplers consisting of 55-µm polyoxymethylene (POM) and 170-µm polydimethylsiloxane were tested for the analysis of polychlorinated dibenzodioxin/furan (PCDD/F) in the pore water and overlying water of the Frierfjord, a bay in southern Norway. This fjord is heavily polluted with PCDD/Fs due to emissions from a former Mg smelter.

Results and Discussion

Field exposures of both equilibrium passive sampler types yielded similar results for freely dissolved PCDD/F concentrations (C W,free) in the overlying water. In addition, the passive sampling data deviated less than an order of magnitude from C W,free obtained with conventional “active” sampling through pumping/filtration over glass fiber filters and polyurethane foam. A similar comparison was done for the pore water, where POM passive samplers also proved to yield freely dissolved pore water concentrations (C PW,free) that deviated less than an order of magnitude from earlier published values measured by direct pore water extraction. The data were also used to derive sediment–water activity ratios, which indicate the diffusive flux direction. High sediment-to-water activity ratios (median value of 160 for 17 congeners) indicated a strong diffusion gradient between the sediment pore water and the overlying water, probably due to deposition of particle-bound PCDD/Fs in combination with low sedimentation rates.

Responsible editor: Gijs D. Breedveld