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]