Global climate change and contaminants—an overview of opportunities and priorities for modelling the potential implications for long-term human exposure to organic compounds in the Arctic

Abstract

This overview seeks to provide context and insight into the relative importance of different aspects related to global climate change for the exposure of Northern residents to organic contaminants. A key objective is to identify, from the perspective of researchers engaged in contaminant fate, transport and bioaccumulation modelling, the most useful research questions with respect to projecting the long-term trends in human exposure. Monitoring studies, modelling results, the magnitude of projected changes and simplified quantitative approaches are used to inform the discussion. Besides the influence of temperature on contaminant amplification and distribution, accumulation of organic contaminants in the Arctic is expected to be particularly sensitive to the reduction/elimination of sea-ice cover and also changes to the frequency and intensity of precipitation events (most notably for substances that are highly susceptible to precipitation scavenging). Changes to key food-web interactions, in particular the introduction of additional trophic levels, have the potential to exert a relatively high influence on contaminant exposure but the likelihood of such changes is difficult to assess. Similarly, changes in primary productivity and dynamics of organic matter in aquatic systems could be influential for very hydrophobic contaminants, but the magnitude of change that may occur is uncertain. Shifts in the amount and location of chemical use and emissions are key considerations, in particular if substances with relatively low long range transport potential are used in closer proximity to, or even within, the Arctic in the future. Temperature-dependent increases in emissions via (re)volatilization from primary and secondary sources outside the Arctic are also important in this regard. An increased frequency of boreal forest fires has relevance for compounds emitted via biomass burning and revolatilization from soil during/after burns but compound-specific analyses are limited by the availability of reliable emission factors. However, potentially more influential for human exposure than changes to the physical environment are changes in human behaviour. This includes the gradual displacement of traditional food items by imported foods from other regions, driven by prey availability and/or consumer preference, but also the possibility of increased exposure to chemicals used in packaging materials and other consumer products, driven by dietary and lifestyle choices.

Baltic Sea sediment records: Unlikely near-future declines in PCBs and HCB

“…Sedimentation rates are within a factor 1.5 in the Arkona Basin and Baltic Proper and can thus not explain the differences in contaminant concentrations. One hypothesis that at least partly may account for the elevated concentrations in the Baltic Proper is that the settling organic matter in the Baltic Proper mainly consists of "fresh" autotrophic organic matter, which may have a higher fugacity capacity compared to "old" and terrestrial organic matter (Armitage et al, 2011). This would imply a higher ratio of organic contaminants to organic carbon in the Baltic Proper compared to e.g., the Arkona Basin where the settling organic matter may consist of a higher proportion of terrestrial organic carbon.…”

Step changes in persistent organic pollutants over the Arctic and their implications

“…Fluctuations of many POPs on interannual or longer timescales, however, have been observed in POP time series collected from arctic monitoring stations. The longterm trends of POPs in the Arctic have been attributed to the changes in their primary emissions, use patterns, retreating sea ice, degradation, and other complex natural and anthropogenic activities (Macdonald et al, 2005; UNEP/AMAP, 2010; Armitage et al, 2011;Kallenborn et al, 2012). The fluctuations of monitored POP atmospheric concentrations have been also associated with interannual climate change at several POP monitoring sites where the longest atmospheric monitoring programs have been operated, notably the Great Lakes region and the Arctic (Ma et al, 2004a;MacLeod et al, 2005;Wang et al, 2010).…”

“…This raises the question of whether currently available POP observational data sets are long enough to address climate change influence on their environmental fate. Several recent modeling investigations and sensitivity analysis to the long-term trend of PCBs and α-HCH in the 20th and 21st centuries suggested that the longterm trends of these POPs were associated more strongly with changes in their emissions and physical-chemical properties, whereas climate change signals were weaker in observed POP time series (Wöhrnschimmel et al, 2013;Armitage et al, 2011;Gouin et al, 2013;Li, 2012).…”

Waterborne and Foodborne Diseases, Climate Change Impacts on Health

“…The fate and transport of chemicals in the natural environment will also change in the future. Rising temperatures will increase rates of volatilization and thereby the long-range transport of POPs (Armitage et al 2011) and local exposure to pesticides (Boxall et al 2009). Climate-induced changes in hydrological cycles and regimes will change how contaminants are transported into the aquatic environment, as well as the dilution potential of rivers and streams.…”