Blast from the Past: Melting Glaciers as a Relevant Source for Persistent Organic Pollutants

Abstract

In this study, the hypothesis that melting Alpine glaciers may represent a secondary source of persistent organic chemicals is investigated. To this end, a dated sediment core from a glacier-fed lake (Lake Oberaar, Switzerland) was analyzed for a wide range of persistent organic pollutants, organochlorine pesticides, and synthetic musk fragrances. Input fluxes of all organochlorines increased in the 1950s, peaked in the 1960s-1970s, and decreased again to low levels in the 1980s-1990s. This observation reflects the emission history of these compounds and technical improvements and regulations leading to reduced emissions some decades ago. The input of synthetic musks remained at a high level in the 1950s-1990s, which is consistent with their relatively constant production throughout the second half of the 20th century. Since the late 1990s, input of all compound classes into the high-Alpine Lake Oberaar has increased sharply. Currently, input fluxes of organochlorines are similar to or even higher than in the 1960s-1970s. This second peak supports the hypothesis that there is a relevant release of persistent organic chemicals from melting Alpine glaciers. Considering ongoing global warming and accelerated massive glacier melting predicted for the future, our study indicates the potential for dire environmental impacts due to pollutants delivered into pristine mountainous areas.

Glacier change in the Cariboo Mountains, British Columbia, Canada (1952–2005)

“…They contribute meltwater along with organic and inorganic materials to freshwater systems (Bogdal et al, 2009;Hood et al, 2009;Moore et al, 2009;Marshall et al, 2011). These inputs, along with downstream impacts, are altered when glaciers undergo changes in extent and volume.…”

Temporal variations of perfluoroalkyl substances and polybrominated diphenyl ethers in alpine snow

“…Accumulating persistent organic pollutants in the European Alps is a concern as glaciers preserve pollutants and can later release these pollutants into regional water resources (Bogdal et al, 2009). The Alps are the largest natural air barrier in central Europe and a potential trap for European anthropogenic atmospheric pollution (Eichler et al, 2004).…”

Increasing and decreasing trends of the atmospheric deposition of organochlorine compounds in European remote areas during the last decade

“…Analogously, melting glaciers in high mountain regions have been suggested as potential secondary sources of POPs released to Alpine lakes (Schmid et al, 2011;Blais et al, 2001), especially for PCBs (Bogdal et al, 2010). Indeed, increasing concentrations of POPs have been recently observed in sediments of Lake Oberaar, a glacier-fed lake in Switzerland, and the trend was attributed to glacier melting and remobilization of ice-trapped compounds (Bogdal et al, 2009). Taking into account that high European mountain regions are enriched in more chlorinated PCBs due to selective accumulation in these cold areas (Grimalt et al, , 2004b(Grimalt et al, , 2009, we hypothesize that re-emission of these pollutants as a consequence of glacier melting could be responsible for the observed higher contribution of these congeners to the atmospheric deposition samples collected in 2001-2002 and 2004-2006 with respect to those collected in 1996-1998 and the increasing concentrations observed in their long-term temporal trends.…”

“…These processes may be particularly significant in remote cold regions, since POPs accumulated in soils and snow/ice surfaces of these areas in the past (Grimalt et al, , 2004b(Grimalt et al, , 2009Guazzoni et al, 2011). Indeed, recent studies have provided evidence that revolatilization has already begun in polar (Ma et al, 2011;Wong et al, 2011) and Alpine regions (Bogdal et al, 2009).…”