Assessment of marine sediment remediation efficiency with SPME-based passive sampling measurement

Ian J Allan,Violette Raffard,Alfhild Kringstad,Kristoffer Næs

doi:10.1016/j.scitotenv.2020.143854

Abstract

Passive sampling has been shown to be a suitable procedure to assess the risk of contaminated sediments through the measurement of freely dissolved concentrations (CFree) and remedial actions involving amendments such as activated carbon (AC). Here we report results of the application of simple, solvent-free solid phase micro extraction methodology (SPME) to assess the performance of different materials for the remediation of selected Norwegian harbour sediments contaminated with polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). AC amendments enabled a reduction of the availability of PAHs and/or PCBs by a factor of ten to over one hundred in Aker Brygge sediments (Oslo) and sediments from Elkembukta, impacted by industrial emissions of PAHs with/from coal tar pitch. Another material, anthracite, slightly less effective in this set of experiment than AC, showed nonetheless great promise as capping material. The SPME data are put in perspective with equilibrium measurements of CFree for PAHs and organochlorines with silicone rubber in other Elkembukta sediments collected in the vicinity of those used for the remediation experiments. A reduction of sediment Cfree for pyrene, benzo[a]pyrene and benzo[ghi]perylene in inner Elkembukta sediment from on average 407, 6.3 and 0.82 ng L−1 to values of/or below 1.3, 0.15 and 0.076 ng L−1, respectively can be expected upon remediation with AC. For the outer, less contaminated Elkembukta sediment, Cfree would reduce from 36, 0.81 and 0.13 ng L−1 to value of or below 0.06, 0.03 and 0.005 ng L−1 for these three compounds, respectively. Differences in pattern of PAH and organochlorine contamination of inner and outer Elkembukta sediments are discussed.

Highlights

Amendment of sediments with strongly sorbing materials such as activated carbon has been shown to be very efficient in reducing freely dissolved hydrophobic organic contaminant concentrations in sediments (Ghosh et al, 2011; Patmont et al, 2015)
We report CFree measurements for polycyclic aromatic hydrocarbons (PAHs) and organochlorinated compounds undertaken with silicone rubber in eight sediment samples collected on a transect across inner and outer Elkembukta in the vicinity of sampling locations for sediments used in the remediation experiments
The accumulation curves appear generally to follow a fast rate of accumulation followed by a plateauing which is consistent with a static passive sampler exposure in sediments

Summary

Introduction

Amendment of sediments with strongly sorbing materials such as activated carbon has been shown to be very efficient in reducing freely dissolved hydrophobic organic contaminant concentrations in sediments (Ghosh et al, 2011; Patmont et al, 2015). We have applied a simple methodology based on the use of solid-phase microextraction (SPME) fibres with a polydimethylsiloxane sorbent phase to investigate the availability of PAHs and organochlorinated compounds in selected coastal/harbour sediments upon amendments with various potential remediation materials In this methodology, a direct insertion of SPME fibre into sediment for exposure is followed by a solvent-free single-step extraction/analysis by gas chromatography- mass spectrometry (GC/MS). A direct insertion of SPME fibre into sediment for exposure is followed by a solvent-free single-step extraction/analysis by gas chromatography- mass spectrometry (GC/MS) This procedure was applied to three different sediments, one from Aker Brygge marina in Oslo and two from Elkembukta (inner and outer) in Kristiansand fjord (Norway). The area referred to as outer Elkembukta is part of wider fjord named Fiskåbukta and shows lower but still elevated levels of PAHs (Σ16PAHs ~ 55 μg g−1)

Methods

Results

Conclusion