Revolatilization of persistent organic pollutants in the Arctic induced by climate change

Journal name:
Nature Climate Change
Volume:
1,
Pages:
255–260
Year published:
DOI:
doi:10.1038/nclimate1167
Received
Accepted
Published online

Persistent organic pollutants (POPs) are organic compounds produced by human activities that are resistant to environmental degradation. They include industrial chemicals, such as polychlorinated biphenyls, and pesticides, such as dichlorodiphenyltrichloroethane. Owing to their persistence in the environment, POPs are transported long distances in the atmosphere, accumulating in regions such as the Arctic, where low temperatures induce their deposition1, 2. Here the compounds accumulate in wildlife and humans, putting their health at risk1, 3, 4. The concentrations of many POPs have decreased in Arctic air over the past few decades owing to restrictions on their production and use. As the climate warms, however, POPs deposited in sinks such as water and ice are expected to revolatilize into the atmosphere5, and there is evidence that this process may have already begun for volatile compounds6. Here we show that many POPs, including those with lower volatilities, are being remobilized into the air from repositories in the Arctic region as a result of sea-ice retreat and rising temperatures. We analysed records of the concentrations of POPs in Arctic air since the early 1990s and compared the results with model simulations of the effect of climate change on their atmospheric abundances. Our results indicate that a wide range of POPs have been remobilized into the Arctic atmosphere over the past two decades as a result of climate change, confirming that Arctic warming could undermine global efforts to reduce environmental and human exposure to these toxic chemicals.

At a glance

Figures

  1. Detrended (residual) and normalized (by the standard deviation) anomaly of weekly sampled air concentrations (pg[thinsp]m-3) from 1993 to 2009 at the Zeppelin Station.
    Figure 1: Detrended (residual) and normalized (by the standard deviation) anomaly of weekly sampled air concentrations (pgm−3) from 1993 to 2009 at the Zeppelin Station.

    ac, α-HCH (a), p,p′-DDT (b) and cis-chlordane (c) (solid lines) from 1993 to 2009. Linear trends of the normalized mean air-temperature anomaly (blue dashed line) and normalized mean ice cover (red dashed line) over the Arctic are also presented. The air temperature and ice-cover data were collected from the National Oceanic and Atmospheric Administration’s National Centers for Environmental Prediction/Department of Energy Reanalysis 2 (ref. 31). The detrended weekly time series of the chemicals are positively correlated with the weekly moving averages of mean air temperature (°C) and negatively correlated with the weekly moving averages of mean ice cover (%) over the Arctic. For instance, there is a statistically significant negative correlation (2000–2009) between detrended α-HCH and ice cover at r=−0.38 (p=1.65×10−17, n=468). Other correlations between the weekly detrended time series of selected chemicals and SAT/ice cover were not quantified because of a number of missing weekly measurement data of the chemicals.

  2. Comparison of modelled, detrended and measured air concentrations (pg[thinsp]m-3) of HCHs, PCBs and
p,p[prime]-DDT.
    Figure 2: Comparison of modelled, detrended and measured air concentrations (pgm−3) of HCHs, PCBs and p,p′-DDT.

    a, Modelled annual air-concentration perturbations of HCHs and PCBs in the closed air–water system from 1991 to 2100 under the IPCC multimodel ensemble average of annual SAT anomalies (°C) over the Arctic under SRES emissions scenario A1B. Annual SAT anomalies (T′) are shown by the black dashed line and scaled on the second right-hand-side y axis; PCBs (scaled on the first right-hand-side y axis) and HCHs (scaled on the left-hand-side y axis) are presented by coloured solid lines. b, Perturbed (in the air–water system), detrended and measured (normalized by standard deviation) summer α-HCH air concentration at the Zeppelin Station. c, Perturbed (in the air–water system), detrended and measured (normalized by standard deviation) summer p,p′-DDT air concentrations at the Zeppelin Station. Modelled summer air-concentration perturbations of α-HCH and p,p′-DDT used summer air-temperature anomalies T′ from 1993 to 2009 calculated as the departures from the mean air temperature averaged over 1948–2009 in the Arctic region.

  3. Correlation coefficients between monitored mean air concentration (pg[thinsp]m-3) of
[alpha]-HCH at the Zeppelin Station and gridded mean SAT and ice cover across the Arctic, and CanMETOP modelled air-water exchange flux (ng[thinsp]m-2) of
[alpha]-HCH.
    Figure 3: Correlation coefficients between monitored mean air concentration (pgm−3) of α-HCH at the Zeppelin Station and gridded mean SAT and ice cover across the Arctic, and CanMETOP modelled air–water exchange flux (ngm−2) of α-HCH.

    a, Spatial-correlation map showing gridded correlation coefficients at 1°×1°latitude/longitude between detrended α-HCH air concentrations at the Zeppelin Station and gridded mean SAT at 1°×1° latitude/longitude in the summers from 2000 to 2009 (warm red/orange shades indicate positive correlation). b, The same as a but for correlations between detrended α-HCH air concentrations at the Zeppelin Station and gridded ice cover (cool blue/purple shades indicate negative correlation). The SAT and ice-cover data used in a and b were collected from the National Oceanic and Atmospheric Administration’s National Centers for Environmental Prediction/Department of Energy Reanalysis 2 (ref. 31). c, CanMETOP modelled anomaly of α-HCH air-water exchange fluxes (ngm−2) in 2007 across the Arctic Ocean. Fluxes were calculated by subtracting the fluxes modelled using summer meteorology and ice cover averaged over 1969–2003 from the fluxes modelled using daily summer meteorology and ice cover in 2007.

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Author information

Affiliations

  1. Air Quality Research Division, Environment Canada, 4905 Dufferin Street, Toronto, Ontario M3H 5T4, Canada

    • Jianmin Ma &
    • Hayley Hung
  2. Yantai Institute of Coast Zone Research, CAS, 17 Chunhui Road, Yantai, China

    • Chongguo Tian
  3. Norwegian Institute for Air Research, P.O. Box 100, NO-2027 Kjeller, Norway

    • Roland Kallenborn
  4. Department of Chemistry, Biotechnology and Food Science (IKBM), Norwegian University of Life Sciences (UMB), Christian Magnus Falsen vei, Postbox 5003, NO-1432 Ås, Norway

    • Roland Kallenborn

Contributions

J.M. designed the research; J.M., H.H. and R.K. contributed and analysed data; C.T. carried out modelling and J.M. and H.H. wrote the manuscript.

Competing financial interests

The authors declare no competing financial interests.

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