Environmental Engineering Reference
In-Depth Information
Climate Change, POPs and Mercury: A Conspiracy of
Impacts
We have not quite reached the present day in our review of POPs and mercury in the Arctic.
We earlier learned that when POPs are released into the environment, these persistent chem-
icals can pass into the atmosphere and be transported long distances very quickly. However,
their volatility is temperature dependent and therefore they can condense out of the environ-
ment at colder temperatures. This process, known as
cold distillation
(or condensation), can
therefore result in POPs becoming trapped in such cold ecosystems as the Arctic. One of the
methods used by scientists to study the global behaviour of POPs released into the environ-
ment is known as
mass balance modelling
. The details are complicated, but the concept is
simple and involves calculating how much of a given mass of a particular POP with its own
uniquephysicalproperties(particularlythoseresponsibleforvolatility)willmove(partition)
into environmental elements (reservoirs or sinks), such as air, marine waters, freshwaters,
marine and freshwater sediments and soil. Once a substance is no longer being released by
humankind, the inventory of substances in these compartments will move towards an equi-
librium-thebehaviourofwhichwillbedeterminedbyitsownphysicalpropertiesandthose
of its “host” environment.
So far, so good, but some readers have probably already guessed where this is going.
Our global climate is warming, and in the climate chapter, we will see that the Arctic is
warming at twice the global rate. The key physical property controlling movement between
reservoirs and to different latitudes is volatility, which is generally temperature dependent.
Robie Macdonald first pointed out to AMAP that mass balance models would likely predict
a reshuffling of the POPs inventories between environmental compartments and a further
poleward migration of POPs. I have worked on and off with Robie since the early 1990s.
Every scientific activity needs an individual like him - a person with an impeccable reputa-
tion in his own field of marine chemistry but who somehow manages to keep abreast of an
eclectic rangeofotherdisciplines. Habitually lookingoverthehorizoninunusualdirections,
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