Combined effect of pollutants studied in the Arctic
Researchers from the Fram Centre in Norway are conducting studies in Arctic waters to determine whether the combined effect of several pollutants could be more severe than the sum of their individual effects.
When looking at the effects of contaminants in the environment, many studies focus on a single substance (such as mercury or PCB) and then observe how it affects different organisms. But as noted by Anita Evenset, from Norway’s Akvaplan-niva research institute, “Under natural conditions, animals are exposed to a cocktail of contaminants simultaneously - PCBs, brominated compounds, phosphorylated compounds, metals and more.
“Many studies in the past have failed to look at how these contaminants work and act together,” Evenset continued. “There is a real lack of knowledge of how these contaminants affect wildlife in a natural setting.”
It is, in fact, possible that when organisms are exposed to many contaminants at once, the damaging effects of each substance are magnified, making the mixture far more dangerous than the sum of its ingredients. The presence of persistent organic pollutants (POPs) in Arctic ecosystems is particularly threatening for those animals at the top of the food chain, with high concentrations of such pollutants being found in predators such as polar bears.
Evenset has been studying the transport of contaminants to and within the Arctic environment for many years. When she and her team came to Bjørnøya (Bear Island), they found a lake which contained extremely high levels of POPs, which are usually associated with nearby industrial activity or human habitation. Similar lakes nearby, however, showed a mere fraction of the contamination.
It became apparent that the lake was inhabited by large numbers of seabirds that were acting as vectors for the contamination through deposits of guano, feathers and other organic materials. The presence of another lake in close proximity, with a similar ecological structure but low levels of contamination, provided an ideal field laboratory for the researchers to study the effects of the contamination levels on populations such as fish.
The results of this project could be significant for environmental managers. Present legislation is based on single-compound assessments, but more accurate guidelines for acceptable concentrations of substances could be developed with more detailed knowledge of how organisms react to combinations of contaminants.
“I believe that we still need more studies looking at different physiological responses in order to get a broader picture of what is happening,” said Evenset. “There are many different processes that can be affected by contaminants that we can’t possibly look at in this one project. It would also be good to look at other animals such as mammals to investigate the difference in, eg, metabolic response.”
Projects such as this will help scientists to gain a deeper understanding of how these contaminants enter the Arctic ecosystem, how they affect the development of organisms within the ecosystem and what constitutes an unacceptable level of contamination.
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