SPEA researcher studies atmospheric contamination of Great Lakes system
Despite decades of efforts to clean up the Great Lakes, pollutants are entering them every day from what might seem like an unexpected source: the air.
A researcher and his assistants at Indiana University are monitoring that air and its contaminants - and have been for more than a decade.
Ron Hites, a professor in the School of Public and Environmental Affairs, and the project he leads with research scientist Ilora Basu, recently received a $5 million grant from the U.S. Environmental Protection Agency to continue work that both influences environmental policy and documents the effects of changes to it.
The Integrated Atmospheric Deposition Network is a joint project with Canada to monitor water pollution caused by air pollution in the Great Lakes. The Hites lab is responsible for U.S. data collection and analysis.
Air quality is monitored at three rural sites on the shoreline of lakes Superior, Michigan and Erie, with data collection every 12 days. Canada has monitoring sites on lakes Huron and Ontario. This study has been going on since 1990, and Hites has been overseeing it since 1994. Such long-term data can show clear effects of, for example, new restrictions on use of pesticides.
The network monitors polychlorinated biphenyls (PCBs), organochlorine pesticides, polycyclic aromatic hydrocarbons (PAHs) and trace metals such as lead and cadmium - substances which are harmful in the environment not only because of their toxicity, but because of their persistence. Some of these substances bioaccumulate: as tiny amounts are ingested by animals or people, they can build up to dangerous levels.
Two more data collection sites are downwind of big cities: Chicago and Cleveland. Those sites show that cities send high concentrations of contaminants into the lakes through the air.
"Thirty years ago, most water contamination came from rivers. One big sources of PCBs in Lake Michigan was Johnson Outdoor Motor Co.," Hites said in a telephone interview. "They were using PCBs in outboard motor manufacturing, and discharging it directly into the lake.
"Direct, point sources (of pollution) are easy to find, and easy to turn off. Most point sources were eliminated in early to mid-1980s. Occasionally there are new ones. But now, most contamination is from atmospheric deposition" - that is, caused by air pollution.
Hites' lab measures both wet deposition - air pollution that rain picks up and drops - and dry - particles that fall out of the air.
He said the $5 million grant will help pay the four technical staff members, one grad student and one post doctoral researcher at IU, plus the five site operators who staff the monitoring stations.
IADN researchers don't sample water in the Great Lakes, and long-term data on Great Lakes water quality doesn't exist.
But longitudinal data on Great Lakes fish does exist - fish that have been swimming in the waters, consuming pollutants for years.
And Hites said there's a clear relationship between the contaminants researchers find in the air and in the fish.
"Think about Lake Superior. There's nothing up there except Duluth, and everyone leaves in winter," Hites joked. "So how does Lake Superior get polluted? Big cities like Chicago put stuff into atmosphere, it drifts all over the place and comes down in Lake Superior," he said. "It ends up in fish from atmospheric delivery of pollutants that originated in cities."
Most people think of PCBs as being in the ground, not in the air. Even in Bloomington, where PCB contamination from old industrial uses remains a problem, the ambient level of PCBs in the air is not worth worrying about, Hites said.
Although PCBs were banned in 1976, more enter the Great Lakes every day, Hites said, often "from dump sites in Chicago and sludge drying fields."
The federal ban of PCBs prevented manufacture and use in new products, but the substance remain legal in closed applications such as capacitors and transformers, designed to be sealed and never opened. When such devices are taken out of use, they can end up in junk yards, where they can be damaged and inadvertently opened. The liquid contents can seep out and volatilize - turn into a gas - be picked up by the wind, then dropped into the lakes.
"In in the '80s, the concentration (of PCBs) in the environment and in fish in the Great Lakes did decrease dramatically, by a factor of two or three," Hites said. That's when point sources of the contaminant were found and shut off.
"Since then, PCB concentrations haven't changed much on average. The reason, we think, is that there continue to be sources: some transformers and capacitors (that contain PCBs) are still in use. Imagine in Chicago, a building is torn down. Ballasts in old fluorescent lights used to contain PCBs. When they bust, the PCBs go into atmosphere. Or if there's a fire (in an old building)."
On the other hand, consider lindane, a persistent chlorinated pesticide. Canada banned its use as a seed treatment in 2004, and the U.S. in 2009, although it's still legal for head lice treatment.
"Its concentrations (in the Great Lakes) have gone down dramatically. The graph shows rapid, exponential decrease. The ban was effective," Hites said.
Hites said the EPA and the Great Lakes National Program Office are most interested in his results, and because it is an international project, reports are exchanged with Canada, and distributed to all eight Great Lake states.
Environmental scientists generally agree, Hites said, that the bans on persistent toxic compounds such as DDT and PCBs have been generally effective.
"Some people say we shouldn't have banned them," Hites said.
"But it's harder to determine indirect effects of compounds, like on calcium metabolism," Hites said, referring to DDT's link to weakened eggshells in fish-eating raptors.
"The main problem isn't the toxicity (of the compounds), but their persistence. Chemists love them. They're easy to make and have an infinite shelf life. That's the problem. When they get out in the environment, the unintended consequences show up. If DDT degraded after two years, it wouldn't be so much of a problem. If you can think of all the possible consequences (of a persistent toxic compound in the environment), it wouldn't be a problem. But you can't," Hites said.
--by Dawn Hewitt
Courtesy of Herald Times
For more information on how air pollution becomes water pollution in the Great Lakes, see www.epa.gov/glnpo/glindicators/air/airb.html.