‘Emerging’ contaminants an increasing concern
Narragansett, RI – A chemical oceanographer at the University of
Rhode Island who measured organic pollutants in the air and water
around Lake Erie and Lake Ontario has found that airborne emissions
are no longer the primary cause of the lakes’ contamination.
Instead, most of the lakes’ chemical pollutants come from sources on
land or in rivers.
According to Rainer Lohmann, professor of chemical oceanography at
the URI Graduate School of Oceanography, water quality in the Great
Lakes has been slowly improving for many years. Historic studies of
the lakes has usually pointed to atmospheric deposition as the
primary cause of pollution in the lakes – from industrial emissions,
motor vehicle exhausts and related sources. But as air pollution has
decreased, he has found a shift in the source of Great Lakes
chemical pollutants.
“Some contaminants still come from the atmosphere, but it is now
mostly from wastewater plants, contaminated industrial sites and
inputs from major rivers,” Lohmann said. “It’s quite a bad mix, but
it’s getting better. And hopefully the Great Lakes Restoration
Initiative will improve things even more.”
His research was reported today at the annual fall meeting of the
American Geophysical Union in San Francisco.
Lohmann and a team of volunteers deployed passive samplers – sheets
of polyethelene that absorb pollutants – in the air and water at
more than 30 sites around Lake Erie and Lake Ontario from 2011 to
2014. Following chemical analysis, he determined the quantity and
source of a variety of pollutants in the lakes.
Legacy pollutants – those that have been banned for decades but
still are detected at relatively high levels, like pesticides and
PCBs – have declined considerably in the lakes, except near the
outflows of the Detroit River and the Niagara River and, to a lesser
extent, near Erie and Rochester. The waters around Cleveland,
however, have lower concentrations of these legacy pollutants.
“Because these pollutants have been banned for such a long time,
they’re no longer in the atmosphere in high concentrations and so
aren’t entering the lakes that way,” said Lohmann. “But we still see
evidence of them coming from Superfund sites and old industrial
sites. And the lakes are now cleansing themselves by releasing these
old pollutants back to the atmosphere.”
Of increasing concern, according to the URI professor, is a group of
what he calls “emerging contaminants” that are increasingly being
detected in water bodies around the world. These include personal
care products, like synthetic musks, and industrial flame
retardants, among others.
“Musks come from products like deodorants and shampoos, so they are
primarily detected near where lots of people live, since they don’t
get broken down in wastewater treatment facilities,” Lohmann said.
“As the lakes are slowly being cleaned of old organic pollutants,
they are replaced by all kinds of compounds of emerging concern.”