Persistent Organic Pollutants and Heavy Metals (Including Mercury) - The Changing Arctic Environment: The Arctic Messenger - page 177

the North American Rocky Mountains and the European Alps. Cold condensation works
wherever it is cold.
We can now take a very brief and selective look at some of the most significant recent
developments in knowledge about POPs and the Arctic. For this, my main source of in-
formation has been the 2009 AMAP POPs Assessment and the 2009 AMAP Assessment
of Human Health in the Arctic . We will encounter the term legacy POPs frequently in
the following pages. It is used to group together substances no longer used or ones used
only under strict controls and where present-day emissions are mainly from such second-
ary sources as soils and water. Such emissions are therefore a “legacy” of past uses. It is,
however, a fluid definition because several of the substances referred to as “new POPs”
as recently as 2008 are now moving or have moved into the category of legacy POPs fol-
lowing the curtailment of their use due to new international controls. At the same time, re-
search and monitoring are resulting in new substances now being identified as “new/emer-
ging POPs”.
Most of the legacy POPs have been showing a general decline in the atmosphere at
rates that would be expected given their different atmospheric half-lives and the time that
has passed since their use has been severely restricted or banned. However, for some of
these substances (such as PCBs and HCB), atmospheric levels increased between 2002 and
2004 at Zeppelin, the air-monitoring site on Svalbard at Ny-Ålesund. This may signal that
warmer temperatures are causing these POPs to reenter the atmosphere from, for example,
reservoirs stored in Arctic soils. It is similarly believed that recent ice-free winters have
been allowing the ocean to “de-gas” some of its POPs inventory back into the atmosphere.
This mechanism has already been observed for alpha-HCH, a component of the pesticide
lindane. Episodes or pulses of increased PCBs, the pesticide chlordane and the DDT deriv-
ative DDE (dichlorodiphenyldichloroethylene) in the atmosphere have also been observed
at Zeppelin and are thought to have been caused by the mobilization of these substances
from vegetation during forest fires. The frequency of such fires is increasing (fulfilling a
long-held prediction of the IPCC). An emerging question for POPs and heavy metals (par-
ticularly mercury) is to understand how much a warming climate will remobilize these sub-