PCDD/F release during benthic trawler‐induced sediment resuspension

Abstract

Benthic trawling can cause the resuspension of large amounts of sediments. Such regular practice in the Grenland fjord system in the south of Norway has the potential to affect the fate, movement, and bioavailability of sediment-associated polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). A novel mode of exposing passive sampling devices consisting of towing semipermeable membrane devices attached to the trawl net was used to gauge in situ changes in the freely dissolved concentration of PCDD/Fs on benthic trawler-induced sediment resuspension. Significant accumulation of a number of PCDD/F congeners was observed despite the short (5 h) sampler exposure times. On average, a one order of magnitude increase in freely dissolved PCCD/F concentrations was seen within minutes of the sediment being resuspended. This observation was supported by similar changes in filtered PCDD/F concentrations measured by high-volume sampling prior to resuspension and in the sediment plume.

Simulating the uncertain effect of active carbon capping of a dioxin‐polluted Norwegian fjord

“…To represent the background concentrations, 4 pooled samples of cod liver from Skagerrak were included. The data come from various projects and monitoring efforts (Saloranta et al ; Naes et al ; Allan et al ; Eek et al ; Allan et al ; Bakke et al ; Bradshaw et al ; for more details see Supplemental Data). The concentrations were assumed to be log‐normally distributed, reflected in the error model (likelihood function) used in the parameter estimation phase.…”

“…First, the spatial division of the fjords (i.e., the structure) is further increased in resolution, to improve the similarity of the model with the real system and to better represent areas that have been identified for possible large‐scale capping. Second, to calibrate the model and estimate model parameters, we now include newer data from biota, sediment, and water samples taken from the recent monitoring efforts (e.g., Bakke et al ) and projects in the Grenland fjords (Cornelissen et al ; Allan et al ; Allan et al ; Bradshaw et al ; Cornelissen et al ). Third, we include the uncertainty surrounding the effect of a relevant and proposed remediation action, namely, capping parts of the polluted fjords with cleaner sediments infused with active carbon (Schaanning and Allan ; Josefsson et al ).…”

From Incorporation to Toxicity

“…Remobilization of sediment-associated contaminants can occur during natural events, such as tidal movement, floods, and storms, or during human activities such as boat traffic (Superville et al, 2014), dredging, dredge disposal (OSPAR, 2004), and trawling (Allan et al, 2012;Bradshaw et al, 2012). Metal remobilization experiments have been designed for assessing the effects of resuspension (Acquavita et al, 2012;Bataillard et al, 2014;Hamzeh et al, 2014).…”

“…Metal remobilization experiments have been designed for assessing the effects of resuspension (Acquavita et al, 2012;Bataillard et al, 2014;Hamzeh et al, 2014). Field studies using passive sampling devices have also been carried out (Allan et al, 2012;Bradshaw et al, 2012;Superville et al, 2014). The results indicated that metals (in decreasing order: Cd, Ni, Pb, Cu, Zn, Cr) are released rapidly from freshwater sediment with a sharp peak at the beginning of the experiment, followed by a fast coprecipitation and/or adsorption processes on the suspended particles (Hamzeh et al, 2014).…”

Passive sampling methods for contaminated sediments: Risk assessment and management

“…PSMs measuring C free are used in these assessments in Norway (Bakke et al 2010;Saloranta et al 2011). Other PSM applications relevant to these guidelines are in situ or ex situ measurements of sedimentsurface water fluxes from benthic chambers or box cores (Eek et al 2010) and the case study example given later (Allan, Nilsson et al 2012;Allan, Ruus, et al 2012).…”