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International Polar Year 2007–2008 - WMO

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152<br />

IPY 20 07–20 08<br />

pre-dating the use of leaded gasoline additives, about<br />

90% of Pb deposition was anthropogenic. Clearly, the<br />

use of leaded gasoline is only the most recent chapter<br />

in a very long history of atmospheric Pb contamination.<br />

Since the 1970s, Pb enrichments in snow and firn from<br />

Devon Island have gone into decline in response to the<br />

gradual elimination of leaded gasoline. Nevertheless,<br />

using the natural, background Pb/Sc ratio and Pb<br />

isotope data, it is found that at least 90% of the Pb in<br />

the High Arctic is still from anthropogenic sources.<br />

INterContinental Atmospheric Trans port<br />

of Anthropogenic Pollutants to the Arctic<br />

(INCATPA, no. 327 www.ec.gc.ca/api-ipy/default.<br />

asp?lang=En&n=8EBD7558-1) studied the risks<br />

associated with the emissions of POPs and mercury<br />

(Hg) in the Pacific region for the contaminant loads<br />

in the Arctic. Before IPY, air monitoring of POPs and<br />

Hg was performed mainly at Alert, Canada and Ny<br />

Ålesund, Norway in the 1990s under AMAP. Hg has<br />

also been continuously measured in air at Whistler,<br />

B.C. and Amderma, Russia under Environment Canada<br />

and Roshydromet for AMAP, respectively. During IPY,<br />

air measurements of POPs and/or Hg started at Little<br />

Fox Lake, Yukon, Canada; Valkarkai, Russia; Barrow,<br />

Dillingham and Fairbanks, Alaska, U.S.A.; Waliguan, Mt.<br />

Changbai, Wudalianchi and Xuancheng, China; and Ba<br />

Vi, Vietnam. At most stations, these measurements<br />

will continue until spring 2010. Soil and air samples<br />

were collected along the Chilkoot Trail, Yukon/Alaska,<br />

in summer 2007, at different elevations. The purpose is<br />

to investigate the atmospheric deposition of POPs and<br />

emerging chemicals on mountain ranges in the Kluane<br />

National Park, Yukon, Canada. Combined with the air<br />

concentration data collected at Little Fox Lake, this<br />

work will provide insight on the roles that mountains<br />

and forests play in intercepting POPs carried by<br />

trans-Pacific air masses. Another project, Atmospheric<br />

Monitoring Network for Anthropogenic Pollution in<br />

<strong>Polar</strong> Regions (ATMOPOL, no. 76), delivered the first<br />

annual data set on POPs in antarctic air. It also studied<br />

the influence of climate change on atmospheric<br />

distribution patterns of POPs and the identification of<br />

new emerging contaminants in arctic environments.<br />

INCATPA models simulating the transport and<br />

fate of POPs showed that long-range atmospheric<br />

transport (LRAT) of POPs from sources in warm<br />

latitudes to the Arctic occurs primarily at the midtroposphere.<br />

Cold condensation is also likely to occur<br />

at the mid-troposphere over a source region in warm<br />

low latitudes. The temperature dependent vapour<br />

pressures and atmospheric degradation rates of POPs<br />

exhibit similarities between the lower atmosphere<br />

over the Arctic and the mid-troposphere over a tropical<br />

region. Convection over warm latitudes transports the<br />

chemicals to a higher altitude where some of them<br />

may condense/partition to particles or to the aqueous<br />

phase and they become more persistent at the lower<br />

temperatures. Strong winds at the mid-troposphere<br />

then convey the condensed chemicals also to the<br />

Arctic where they can be brought down to the surface<br />

by large-scale descending motion and wet deposition.<br />

These studies provide a new interpretation on the cold<br />

condensation (Arctic trapping) effect and revealed<br />

major atmospheric pathways of POPs to the Arctic.<br />

POLar study using Aircraft, Remote sensing,<br />

surface measurements and model ling of<br />

Climate, chemistry, Aerosols and Transport<br />

(POLARCAT, no. 32 www.polarcat.no) brought<br />

one of the largest atmospheric measurement campaigns<br />

ever conducted in the Arctic. Eight research<br />

aircraft from the United States, France, Germany, Russia,<br />

as well as research groups from many other countries,<br />

flew research missions in nearly all parts of the<br />

Arctic and sub-Arctic during spring 2007, spring 2008<br />

and summer 2008. The campaigns were coordinated<br />

(Fig. 2.1-12) such that comparisons between the different<br />

parts of the Arctic can be made. The aircraft<br />

missions were complemented by a ship cruise in<br />

spring 2008, a railway campaign in Siberia in summer<br />

2008 and measurement campaigns at several<br />

Arctic stations (e.g. Summit, Ny Ålesund). They were<br />

also supplemented with extensive use of satellite remote<br />

sensing products and a large range of different<br />

models. Detailed measurements of the gas-phase and<br />

particulate-phase chemical composition of the Arctic<br />

atmosphere, the optical properties of aerosols, the<br />

properties of clouds, etc. were made. In the result, the<br />

POLARCAT data set will provide a unique reference for<br />

future changes of the Arctic atmosphere.<br />

While the data sets are still being processed and<br />

analyzed, several research highlights were already<br />

published in a POLARCAT special issue in Atmospheric

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