Transport and bioavailability of persistent organic pollutants (POPs) in the arctic environment.
Goal/Aim: To develop a method to evaluate the long-range transport to the arctic environment, transfer of POPs between air and water and the uptake of POPs in biota.
Background: Bio-concentration of persistent organic pollutants (POPs) in the food web is a serious environmental and human health problem in the Arctic. High concentration levels of POPs have been recorded in tissues from both animals and humans, but it is not well-known how these chemicals are incorporated in the food chain. The long-range transport of POPs to the Arctic from the southern parts of the Northern Hemisphere is a major unsolved global problem in understanding why and how POPs are incorporated in the food chain. One way to address this is to use Semi-Permeable Membrane Devices (SPMDs). A SPMD consists of a low-density polyethylene tube containing a lipid in which hydrophobic substances from the surroundings are passively absorbed. SPMDs thus act like a “synthetic biota” capable to up-concentrate organic pollutants from water or air. Furthermore SPMDs is a low cost technique for determination of the composition and concentration of POPs.
Project Description: The project will identify the transfer direction of POPs between air and water using SPMDs. The uptake kinetics of the SPMDs will be determined in the laboratory at conditions simulating the arctic environment. In field experiments SPMDs will be deployed in air and water in a temperate environment and in an arctic environment. The fugacity level will govern the uptake kinetics of the membranes. The fugacity can also be estimated using QSAR (Quantitative Structure Activity Relationship) methods, which opens for the possibility to calculate the concentration levels based on information about the membrane content. The fugacity level determined by the membrane will also be used to evaluate the flux between the compartments. This evaluation will be based on existing compartment models. Concentrations of POPs in the arctic will be compared to the world-production of these compounds . This information will be used in an assessment of the potential long-range transport of POPs into the arctic environment. The SPMDs will only sample the dissolved chemicals and will simulate the passive uptake of hydrophobic compounds by biota. Concentration of POPs in the SPMDs will be used to estimate bioavailable concentration of POPs in the aquatic environment.
Methodology: a) Laboratory experiments. The relationship fugacity level and membrane uptake rate needs to be quantified in laboratory experiments both for air, fresh water and sea water. The results can be evaluated using QSAR methods in order to identify the possibility of calculating concentration levels based on SMPD data. b) Field experiments. SPMDs will be deployed in air and water in Denmark and in the arctics, preferably Greenland. SPMDs will be dialysed to extract POPs from the membranes. The extract will be cleaned up by HPLC gel-permeation and the compounds of interest will be analysed using GC-ECD or GC-MS.
Copenhagen University contact person: Bo Svensmark, email: [email protected]