POPsicles in the Arctic? (Arctic Pollution Part I)

We've already considered one thing (other than climate change) which has the potential to affect the Arctic environment, increasing UV from an 'ozone hole'. Another one of these potential 'things' is pollution, or more scientifically, chemicals and compounds where they're not supposed to be naturally. One things humans have always done is burn things, and the record of these activities is clear in the palaeo-archives, from the prehistoric burning of small wood fires, through large scale burning for clearing right to the modern widescale burning of almost anything and everything seen since the industrial revolution. What is more recent though is the widespread use of pesticides and the growth of heavy industry. We tend to see the Arctic regions as a wilderness, wild and untouched. However, many types of pollutants have been found across the Arctic circle.

In this and the next post, I won't attempt to try and fully describe the extent of Arctic pollution. There are just too many pollutants and studies to do that! Rather, I'm going to focus on a couple of papers which have some interesting findings relating to POPs and SCPs (I did warn you about the acronyms).

States signed up to the Stockholm Convention on Persistent Organic Pollutants (green)
Source: http://toxipedia.org/display/toxipedia/Stockholm+Convention   

The Arctic Monitoring and Assessment Programme (AMAP) was set up in 1991 as part of the inter-governmental 'Arctic Council'. It's website it full of reports, both scientific and for the press which are freely available and are
definitely worth a look. They expressed concern in the 1990s about Persistent Organic Pollutants (POPs) which are chemicals that do not break down naturally but accumulate in organisms (bioaccumulation), increase up the food chain (biomagnification) and have harmful effects on animals and humans. Some are carcinogenic, while others have neurotoxic effects, or damage the liver, immune or hormone systems. Nasty stuff. They include a number of pesticides, industrial chemicals and products of burning, and so industrial countries are often significant sources of these pollutants.

Many POPs have been banned by individual nations, and others are part of an agreement from the Stockholm Convention on Persistent Organic Pollutants. As shown in the picture above, this (non-binding) agreement has been ratified by a large proportion of states. Significantly though, many industrialised countries in the Northern Hemisphere (USA!) have not agreed to it. That's not to say though, that 'green' countries emit far fewer POPs than the US, for example, as the agreement is only good when states stick to it.

As part of the AMAP, Hung et al. (2010) reported on atmospheric monitoring or POPs between 1993-2006. Unsuprisingly, the prevalence of the banned POPs had dropped in the vast majority of cases over the period of study, although they are still present. A significant exception to this rule, though, is hexachlorobenzine (HCB), a fungicide and industrial by-product which is now no-longer used. Surprisingly, levels at some sites had been increasing from around 2003-2006, the opposite trend than expected (see graph below). The authors offered up a number of potential explanations for this, including 'volitization' of the chemical from ocean areas previously covered by sea ice but revealed due to sea-ice melt, and the continued use of pesticides which have HCB as a by-product. This example shows that the temporal patterns of POPs are unpredictable and can possibly be affected by Climate Change. It also shows that banning certain pollutants doesn't mean that levels in the environment will necessarily follow a downward trend. Therefore, continued monitoring and assessment is necessary.

Temporal Trends of HCB at three sites monitored by Hung et al. (2010) direct from article

As well as this, Hung et al. found increasing levels of 'new POPs' which are not part of the banned list and have appeared relatively recently. For example, Polybrominated diphenyl ethers (PBDEs were found to be increasing slowly at the end of the study (2005-6). This is a concerning trend, as the impacts of these 'new POPs' are less well-known, including the potential for interaction with other pollutants. Also, these levels recorded in the atmosphere do not give an indication of bioaccumulation, meaning that these levels may be more serious.

A final interesting point raised by the article is another potential link with climate change. The authors suggest that increased levels of Polychlorinated Biphenyls (PCBs) at one site during 2004 and 2006 were linked to large scale forest and agricultural fires, as 'volitization' of PCBs from the soil is possible during fires. This also leads them to suggest that climate change may cause increased levels of PCBs through an increase in forest fires. This may be a bit far-fetched, but it's certainly a possibility for future patterns of pollution which are potentially uncontrollable.

So to conclude, it's not always a simple cause and effect relationship of banning POPs leads to reduced levels in the environment. The next post will consider SCPs and the extent to which pollution has affected the Arctic when compared to other regions.