Environmental Engineering Reference
In-Depth Information
sation: Sitting on a barrel only 900 kilometres from the pole - at an altitude of 1,730 metres
- with who knows how much ice under your bottom and eating this incredible curry!
The measurements made at Alert used a high-volume air sampler to measure polycyc-
lic aromatic hydrocarbons (PAHs) and POPs at a weekly sampling frequency. The particle
phase of the pollutants was trapped on a glass fibre filter and two polyurethane foam (PUF)
plugs collected the vapour phase. The sampling record from Alert is continuing without
interruption to this day. Between 1992 and 1993, the NCP arranged for four identical
samplers to be deployed: one in the Yukon, one at Cape Dorset, one (through AMAP) at
Dunai Island near the delta of the Lena River in Siberia and one (also through AMAP) in
the western Russian Arctic. Norway had compatible samplers operating at Ny-Ålesund in
Svalbard and the United States installed similar equipment at Barrow in Alaska. Not all
these stations are still operating, but for many years, we had a circumpolar ring sampling
POPs at coordinated weekly intervals. The true wealth of information that was to be de-
livered by the continuous air samplers did not emerge until after the 1994 CLRTAP dead-
line. However, the AMAP contributing scientists had gleaned enough from applying back
trajectory analysis to the circumpolar sampler records to confidently say in the CLRTAP
stateofknowledgereportthattheenvironmentalloadingsofmostPOPsreachingtheArctic
were travelling in the atmosphere from sources in mid-latitudes - usually in the form of
discrete episodes. In western Arctic Canada, pulses could come from as far away as South-
east Asia. In some regions, riverine transport is also important, but even here, it is thought
that much of the riverine loading is from those POPs then being studied having been atmo-
spherically transported to the river's watershed.
Atmospheric transport is swift and measured in days. The report explained that the
oceans are important for the movement of the smaller number of POPs that have a relat-
ively high water solubility (such as HCH), but their movement in this medium is on the
scale of a year or so. Over time, the importance of the oceans will probably turn out to be
their huge capacity to act as a storage reservoir for atmospherically deposited POPs and
therefore a potential source when atmospheric concentrations go down and rising sea tem-
peratures tip the balance towards evaporation. You have probably already realized from
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