Read this and weep- or cough and hack. It has been in the news in scientific journals for a while now.
Trans-Pacific Air Pollution
Kenneth E. Wilkening, Leonard A. Barrie, Marilyn Engle*
The once-pristine air above the North Pacific Ocean is polluted. Pollutants are transported on mid-latitude westerly winds from Eurasia to the Pacific Ocean basin and across to North America. The expected economic expansion around the Pacific Rim and in the rest of the world will deliver even more pollution unless preventative measures are taken. The risk of adverse effects to wildlife, ecosystems, climate, and human health throughout the Pacific region will increase. Even remote areas such as Arctic and alpine environments are threatened. Ocean productivity and the atmospheric energy budget over the North Pacific Ocean could be altered.
Earlier research exists (1), but two recent events have been particularly important in focusing researchers' attention on trans-Pacific pollutant transfer. In 1997, rapid transport of pollutants from Asia to the Olympic Peninsula of Washington State was observed (2). And in April 1998, satellite remote sensing showed aerosols being whisked across the Pacific to North America from a massive dust storm in western China (see the figure) (3). Observational data, computer simulations, and research on pollutant concentrations in various media such as snow, fish, or eagles have since provided additional evidence of a potential pan-Pacific air quality problem. In July 2000, over 100 experts gathered in Seattle, Washington, to synthesize and evaluate the existing knowledge about trans-Pacific pollutant transport and identify research needs (4).
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Pollution from afar. Satellite remote sensing images of trans-Pacific transport of aerosols in April 1998 originating from a massive dust storm in China.
CREDIT: FROM (3)
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Pollutant transport across the Pacific is one of many intercontinental and transoceanic pathways of pollutant transport. Numerous routes exist within the Pacific region, but transport on the mid-latitude westerly winds is dominant. The pollutants may be particles or gases and include coal combustion aerosols, ozone, persistent organic pollutants (POPs), and heavy metals such as mercury. Unfortunately, there are insufficient observational data to provide more than a sketchy picture of transport routes and concentrations. The Pacific Exploratory Mission (PEM)-West campaigns, conducted in 1991 and 1994, were among the first large-scale programs to investigate long-range transport of pollutants in the Pacific (5). Soil dust transported from Asia has been observed at Mauna Loa Observatory in Hawaii for over 30 years; high concentrations of anthropogenic pollutants (including sulfur, black carbon, and enriched trace metals) have also been measured (6). Pollutant outflow from the Asian continent into the air masses above the Pacific is found to be highest in the winter and spring seasons (5). Transit times across the Pacific during this period usually range from 5 to 10 days depending on altitude and weather patterns.
Pollution flowing off the Asian continent reaches North America episodically. At Cheeka Peak Observatory on the coast of Washington State, Jaffe and co-workers (7) have observed five springtime Asian pollution events since 1997. At Tagish in the Canadian Rocky Mountains, Bailey et al. (8) detected elevated levels of pesticides (lindane, chlordane, and DDT) during winter and spring and attributed them to pollution transported from continental Asia. Both studies used computer analysis to trace the origin of the polluted air masses.
Computer simulations of trans-Pacific air pollution transport are numerous. According to one study, between three and five important pollution events associated with meteorological disturbances that entrain pollution from Europe and Asia into westerly winds hit the U.S. west coast between February and May each year (9). Another study finds that a tripling of east Asian anthropogenic emissions from fossil fuel combustion by 2010 compared with 1985 levels could increase ground level monthly mean ozone concentrations in the western United States by 2 to 6 parts per billion (ppb), making attainment of the new U. S. ozone standard more difficult (10). Present background ozone concentrations in surface air over the United States are in the 25 to 55 ppb range.
Pollutant concentrations in snow, fish, wildlife, sediments, and Arctic inhabitants indicate that some substances transported into and across the Pacific may already be working their way into ecosystems and humans. A study on the Fraser River watershed in British Columbia concluded that toxic airborne pollutants from Asia may be a source of contamination in lake fish and sediments (11). Blais et al. (12) found surprisingly high POP concentrations in the snowpack of high mountains in the Canadian west. Edmonds et al. (13) found increased nitrates and sulfates in pristine streams in the Olympic National Forest on the coast of Washington State. Other studies document POPs and mercury in wildlife and human populations in the Arctic (14), pesticides in bald eagles of the Aleutian Archipelago (15), and very high polychlorobiphenyl (PCB) concentrations in some Pacific Northwest orca populations (16). In all of these cases, the origin of the pollutants is undetermined, but long-range atmospheric transport across the Pacific Ocean cannot be ruled out.
Increasing recognition of trans-Pacific air pollution is evident in several new international research programs. For example, ACE-Asia (Aerosol Characterization Experiment-Asia) (17), its attendant Pacific Rim Aerosol Network, and the TRACE-P experiment (TRAnsport and Chemical Evolution over the Pacific) (18) aim to quantify the properties and distribution of aerosols and other atmospheric species in the Asia-Pacific region. The Intercontinental Transport and Chemical Transformation of Anthropogenic Pollution (ITCT) project will focus on atmospheric transport and chemistry over the North Atlantic and North Pacific, and SOLAS (Surface Ocean Lower Atmosphere Study) (19) aims to elucidate the influence of pollutants on interactions of the marine biogeochemical system, the atmosphere, and climate in the Pacific and elsewhere. The U.S. Environmental Protection Agency (EPA), the National Oceanic and Atmospheric Administration (NOAA), and other government agencies are planning atmospheric inflow studies to the west coast of the United States.
Research into the dynamics of long-range transport, deposition, and impacts of atmospheric pollutants in the Pacific region is only beginning. The nature, magnitude, and spatial distribution of the pollutants and their effects are largely unknown. Greatly expanded interdisciplinary and international research effort is required before trans-Pacific air pollution and other environmental issues in the Pacific region can be addressed effectively.
References and Notes
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First International Conference on Trans-Pacific Transport of Atmospheric Contaminants, Seattle, WA, USA, 27 to 29 July 2000, organized by the Nautilus Institute and the U.S. EPA.
J. M. Hoell et al., J. Geophys. Res. 101, 1641 (1996) [ADS]; J. M. Hoell et al., J. Geophys. Res. 102, 28223 (1997) [ADS]; www-gte.larc.nasa.gov/pem/pem_hmpg.htm.
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D. Jaffe et al., J. Geophys. Res., in press; R. Kotchenruther et al., J. Geophys. Res., in press; faculty.washington.edu.
R. Bailey et al., J. Geophys. Res. 105, 11805 (2000) [ADS].
J. J. Yienger et al., J. Geophys. Res., in press.
D. J. Jacob et al., Geophys. Res. Lett. 26, 2175 (1999) [AGU].
R. W. MacDonald et al., Health of the Fraser River Aquatic Ecosystem: A Synthesis of Research Conducted Under the Fraser River Action Plan, Vancouver, BC, C. B. J. Gray et al., Eds. (Environment Canada, Vancouver, 2000), vol. 1, pp. 23-45.
J. M. Blais et al., Nature 395, 585 (1998) [GEOREF].
R. L. Edmonds et al., Vegetation Patterns, Hydrology, and Water Chemistry in Small Watersheds in the Hoh River Valley, Olympic National Park (Scientific Monograph NPSD/NRUSGS/NRSM- 98/02, U.S. Department of Interior, National Park Service, Washington, DC, 1998).
AMAP (Arctic Monitoring and Assessment Programme), AMAP Assessment Report: Arctic Pollution Issues (AMAP, Oslo, Norway, 1998); see www.amap.no/.
R. G. Anthony et al., Environ. Toxicol. Chem. 18, 2054 (1999).
P. S. Ross et al., Mar. Pollut. Bull. 40, 504 (2000)
See saga.pmel.noaa.gov
See www-gte.larc.nasa.gov/trace/tracep.html
See www.ifm.uni-kiel.de/ch/solas/main.html
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K. E. Wilkening is at the International Studies Program, University of Northern British Columbia, Prince George, British Columbia V2N4Z9, Canada. E-mail: kew@unbc.ca L. A. Barrie is at Atmospheric Sciences and Global Change Resources, Pacific Northwest National Laboratory, Richland, WA 99362, USA. E-mail: mailto:leonard.barrie@pnl.govM. Engle is at the Office of International Activities, U.S. Environmental Protection Agency, Washington, DC 20460, USA. E-mail: engle.marilyn@epa.gov
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Volume 290, Number 5489, Issue of 6 Oct 2000, pp. 65-67.
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