Environmental pollution in the Arctic: Chemicals and other stuff5 July 2005 - 25 September 2005
The main goal of this project was to investigate the occurrence, circulation, and fate of organic environmental pollutants in the Arctic. As a side project we also investigated the occurrence of plastic debris in the sea.
It may be difficult to believe that compounds that you can hold as a powder in the palm of your hand can be transported via the air to remote areas. Nevertheless we find today organic contaminants – such as the well known persistent organic pollutant DDT – in all parts of the world, even the parts most remote from the emission sources.
A small proportion of almost all organic compounds occur in the air as a gas. The proportion of any compound in the gas phase will be higher in warm climates than in cold. The global distribution is thought to occur by a temperature driven process in which compounds in the gas phase are “drawn” to the cold polar areas (AMAP 1998). This is called “The Cold Wall Effect” and is similar to what happens when frost accumulates on the cold surface of an ice cream container that is taken out of the freezer on a warm summer day. The water vapour in the air condenses on the cold surface and creates a local depletion of water vapour close to the ice cream container so that more water vapour is “drawn” from the surrounding air towards the container.
The current interest in organic contaminants in the Arctic started in the late 1980’s when it was found that people living in the Arctic have much higher levels of persistent organic pollutants in their bodies than those living in industrialised areas. Recent findings also indicate that some populations of polar bears have such high body burdens of PCB that this affects their reproduction negatively. However, as the Arctic is difficult to access, our knowledge and understanding of the processes that govern the transport of pollutants to and from the Arctic is still fragmentary. We also need to know more about the degradation processes and rate of degradation of organic pollutants in the Arctic. These processes and rates are important to understand the ultimate fate of the contaminants and the time scale of the problem. Another aspect that is of increasing importance is to study “new” contaminants. These are not necessarily new in the sense that their production has started recently; many of them are anthropogenic compounds that have been present in the environment for a long time, but that no one has measured in the field previously. These include some persistent organic pollutants, e.g. brominated flame-retardants with structures related to PCB and DDT, but also currently used pesticides.
Work on board
Our work on the expedition was mainly aimed at sampling air and water for determination of a wide variety of persistent organic pollutants. It is important to sample both water and air to understand the circulation of the pollutants in the area visited. Most of the work was at sea, but during leg 2 we also sampled lake and pond water and plankton. The air sampling is done by sucking large volumes of air (~1 000 m3 per sample) through a sampling train consisting of a filter to catch the particle and two polyurethane foam plugs on which the gaseous compounds of interest are sorbed. The water samples were extracted according to the same principle, but here the water was pressed through the sampling train (a filter and a polymeric sorbent) using nitrogen gas.
Of particular interest are the hexachlorocyclohexanes, a persistent compound class that includes the insecticide lindane. The particular interest tied to these compounds is their use as model compounds; they are relatively easy to determine in water samples of moderate size (4–10 litres) so we can obtain many data points to include in our models. For the other classical persistent compounds we took samples of up to 200 litres or more to obtain reliable data on their concentration in Arctic waters. These samples will also be screened for compounds which were previously thought to be of anthropogenic origin, but which now actually seem to be natural products with properties very similar to the classical persistent compound.
We were the first expedition through the Canadian Arctic to include perfluorinated compounds in our sampling scheme. These are compounds with a wide technical use, e.g. in fire fighting foams and in the textile industry. The one that has gained most interest, perfluoro-octanesulphonic acid (PFOS), is amphiphilic, i.e. it has one water-soluble end while the other is fat-soluble. This was thought to be too water-soluble to accumulate in biota, a presumption that has proved to be utterly wrong. We find PFOS and other similar compounds in biota in the Arctic, so it is important to also understand its dispersal in the water environment.
We also collected samples that will allow the determination of currently used pesticides. Surprising little interest has been given to these compounds outside of the traditional agricultural areas, but when we start looking we find an increasing number of compounds in unexpected places.
Air samples were collected from the North Sea to Beringia, while surface water samples were taken along the entire Oden cruise. Pond water was collected in Chukotka and on Wrangel Island, while a number of deep water profiles were obtained at different locations along the cruise track.
The air and surface water data will be used to calculate the current balance of air transport and deposition/revolatilization of selected contaminants. The deep-water profiles are of particular interest to estimate the microbial degradation rate of chiral compounds. During the expedition Arctic Ocean 1996 we developed a method to use the degradation of chiral compounds to estimate their degradation rate. A chiral compound has a “left-handed” and a “righthanded” form that are physically and chemically similar, but that may have different biological effects and degradation rates. By measuring the two forms separately we can construct a clock to estimate the microbial degradation rate (Harner et al. 1998). The particular hope for this expedition is that we can – together with data from Arctic Ocean 2002 – use the “ventilation age” of the calculated CFC data (obtained by other research groups) to calibrate our calculations of the degradation rates. This should give added value compared to data obtained from expeditions where no CFC data have been available.
At the time of writing this report no results from Beringia 2005 are yet completed; it will take a couple of years before all samples have been analysed.
As a side project we also studied the occurrence of plastic debris along the cruise track and on a shore in Chukotka. Plastic debris in the oceans is an increasing environmental problem (Derraik, 2002). In parts of the Pacific there are six times more miniscule plastic particles than zooplankton of the same size! Marine birds, turtles, and mammals ingest the plastic debris, leading to starvation because of a full stomach. Organic environmental pollutants, such as PCB, may also be sorbed to plastic debris. The debris may, therefore, serve as aconveyor for pollutants into organisms.
There are inventories of plastic debris from the shores of some sub-Antarctic islands, but little previous information on the situation in the Arctic Ocean. With the help of the ornithologists constantly on watch for birds, we counted floating plastic debris along the cruise track from Gothenburg to Beringia; plastic debris was found even in the ice far north of Wrangel Island. On a 2.4 km stretch of the shore at Toygunen we found 663 objects of plastic debris (picture 3)! This included a Swedish made rucksack. It is an indication of the seriousness of the problem that even the shores of the Chukchi Sea, which is ice covered during much of the year, is severely contaminated by plastic debris.
- AMAP, 1998. AMAP Assessment Report: Arctic Pollution Issues. Arctic Monitoring and Assessment Programme (AMAP), Oslo, Norway.
- Derraik, J.G.B. 2002. The pollution of the marine environment by plastic debris: a review. Marine Pollution Bulletin 44, 842–852.
- Harner, T., Kylin, H., Bidleman, T.F., Strachan, W.M.J. 1999. Removal of α- and γ-Hexachlorocyclohexanes and the Enantiomers of α-Hexachlorocyclohexane in the Eastern Arctic Ocean. Environmental Science and Technology 33, 1157–1164.