Geology Reference
In-Depth Information
The two water concentrations (temperate and Arctic) are similar, even
though the air concentration in the Arctic is an order of magnitude
less than temperate air. This temperature driven phenomenon that
favours chemical partitioning to surfaces is commonly known as the
'cold condensation effect' and has resulted in the worrying rise in
persistent organic pollutants in the polar environments.
6.4.3 Partition Maps
The rise in legislation and the concern over the use and release of
chemicals that possess physical-chemical properties that may be analo-
gous to DDT and other persistent organic pollutants such as polychlo-
rinated biphenyls (PCBs), has prompted demand for ways to rapidly
screen or assess chemicals with respect to their environmental distribution
and fate. The environmental transport, lifetime and accumulation of
organic chemicals in different compartments, such as biota, can be
quantified through the use of multi-compartment (media) chemical fate
models. It is simply not feasible to measure all chemicals of concern in a
large number of compartments over an extended period of time. Identi-
fying chemicals of concern, and the designation of the term 'POP' for a
chemical substance, occurs if a chemical meets the criteria specified in
Table 2. Importantly, the designation of 'persistence' is based on the
Table 2 Criteria used to designate a chemical substance as a persistent organic
pollutant or 'POP'. Information from the Stockholm Convention on
POPs
31
t
1/2
a
Persistence
1.
in water 4 2 months
2.
t
1/2
in soil/sediments 4 2 months
3.
Other evidence that the chemical is sufficiently persistent
to justify consideration
Bioaccumulation
1. BCF or Bioaccumulation Factor (BAF) in aquatic
species 4 5000
2. Log K
ow
4 5
3. Evidence of higher bioaccumulation in other species
Potential for long
range transport
1. Measured levels of the chemical in locations distant from
sources of release that are of potential concern
2. Environmental fate properties and/or model results that
demonstrate that the chemical has a potential for
long-range environmental transport
3. t
1/2
in air 4 2 days
a
t
1/2
ΒΌ
half-life.
