Air pollution may travel thousands of miles

Organic pollutants can be transported for thousands of miles, instead of being trapped in oceans or soil as previously thought, so that pollution is not necessarily a local problem, says a team of US scientists.

Researchers from Texas A&M’s Geochemical and Environmental Research Group (GERG) investigating the transport of pollutants such as polynuclear aromatic hydrocarbons (PAHs), pesticides, and polychlorinated biphenyls (PCBs) in the atmosphere and their removal by rain and dust, found that even gaseous water pollutants can evaporate into the atmosphere instead of staying in the oceans.

“Most scientists used to think that organic pollutants were not present as gas in the air,” said Terry Wade, one of the researchers. “To our surprise, we have learned over the last 30 years that organic pollutants can be in the vapour phase, which means that they can be transported over long distances.” One example of this occurs in the Arctic where pesticides such as DDT, chlordane and toxaphene, which are not used in the region, have been found in beluga whales.

“What we do here in Texas can affect what is happening in the Arctic,” said Wade. “We have added these contaminants to the environment, and now we can see that they are showing up in areas where we would not have expected them to be.”

The researchers used samplers to test for pollutants near the university, near Galveston and Corpus Christi bays. “The general principle of the experiments is that you take a sample of air or rain and you measure how much contaminant is present in the rain or in the air,” said Wade. “Then using models, you try to estimate the amount of contaminants that are coming down into the bay.” The study indicates that DDT, PAHs and PCBs evaporate into the atmosphere, and are then able to be transported away.

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