Everglades Success Story Probably Won't be Repeated in Tampa Bay

The stunning reversal of mercury levels in the Everglades probably won't be repeated in the Tampa Bay region, according to Tom Atkeson, mercury coordinator for the Florida Department of Environmental Protection. On the other hand, levels in Tampa Bay and its tributaries were never so high that the state imposed a blanket "no consumption" recommendation for certain fish either.

"It would be hard to repeat the unlikely and dramatic changes in the Everglades because that region was at risk for several reasons," he notes. "The difficulty of siting landfills in South Florida meant it had an atypically high reliance on waste combustion, the highest in the nation in fact."

The effects of mercury also were more pronounced in the Everglades - it's downwind of a major metropolitan area, and it's a large, shallow waterbody where atmospheric deposition can enter and interact with sediments, which transforms mercury to a form that is more bioavailable to fish and birds.

New regulations that became fully effective in 2000 helped to push a large number of medical incinerators out of business, he notes. "Until 1994, there was basically no regulation of small incinerators -they just notified us of what they were doing," he said.

Mercury levels in fish and some wading birds in the Everglades dropped 60 to 70% between 1994 and 2003 as emissions from municipal and medical incinerators were regulated.

A naturally occurring metal, mercury is liquid at normal temperatures and easily transforms into a gas. Like many heavy metals, it is toxic in large doses to mammals, birds and fish, and can cause severe damage to the nervous system, particularly in unborn babies, infants and young children. In Tampa Bay, most of the mercury probably comes from coal-powered electrical generation and that should drop significantly as Tampa Electric Company repowers its Gannon plant and installs new scrubbers at Big Bend.

"From 1990 through 2000 we haven't seen any change in Tampa Bay, but sampling is not set up to detect those changes either," said George Henderson, a biologist at the Florida Fish and Wildlife Research Institute. Fish are sampled strictly so the health department can issue appropriate warnings, he adds.

"There really isn't a research program per se to look at the ramifications of mercury in fish," he adds. "We have all kinds of great ideas for research projects, but it hasn't been a priority for the legislature."

Most of the research has focused on freshwater ecosystems, where fish are more easily contained, but marine fish - particularly large predators like shark and mackerel also are affected, he notes. "The marine system is very much open and water and organisms easily move from place to place so it's much more difficult to track."

Some of the results are counter-intuitive because mercury may attach to sediments, he adds. "There's actually more mercury at the mouth of Tampa Bay where the water is cleaner than in the Hillsborough River."

And even fish with very high levels of mercury - so high that entire zones are closed to fishing - exhibit no signs of mortality or even decreases in population in other parts of the country. "The levels that are potentially harmful to people don't seem to cause harm to fish," Henderson said.

California Study Raises Concern in Tampa Bay

Headlines across the country blared dire warnings when a new study showed that air pollution - even at levels that meet federal standards - causes permanent damage to children's lungs and may result in complications later in life.

But what does a Southern California study mean in Tampa Bay?

"Our pollution levels for nitrogen oxides are below the national standards, but we still should be concerned," said Connie Mizak, a post-doctoral fellow at the University of South Florida's College of Public Health.

The study, detailed in the September 2004 issue of the New England Journal of Medicine, found a negative correlation between air pollution and lung capacity in children, Mizak explained. In other words, as air pollution levels increase, permanent lung capacity decreases.

The study measured lung capacity in healthy children over an eight-year period, from fourth grade to high school graduation. Researchers expected lung capacity to increase as the children grew. What they found was that lung capacity grew less than expected in areas with high levels of air pollution, with effects similar to those reported for children exposed to maternal smoking.

"They describe the lung damage observed in Southern California as potentially increasing the risk for lifethreatening illnesses in adulthood," Mizak notes. "That isn't likely to be the case here, but even with relatively good air quality, there still may be some effects."

The challenge in Tampa Bay, she adds, will be controlling increased contaminant levels as the region's population continues to grow. "As more and more people move into the area, traffic emissions will likely increase due to urban sprawl. That's somewhat balanced by the fact that we're driving cleaner cars, but I still think we have to work diligently to encourage the public to adopt responsible lifestyle behaviors such as carpooling. Reducing the number of cars on the road will help reduce automobile emissions and prevent these types of damaging health effects."

editors
Mary Kelley Hoppe
Victoria Parsons
contributing writers
Kristin Thoms
Benjamin Preston
editorial advisory board
Suzanne Cooper
Tampa Bay Regional Planning Council
Dick Eckenrod
Tampa Bay Estuary Program
Frank Hearne
Mechanik, Nuccio, Williams, Hearne & Wester, P.A.
Allan Horton
Retired Newspaper Editor
Robin Lewis
Lewis Environmental Services
Don Sayre
Florida Power & Light
Francia Smith
Sawgrass Lake Park
Beth Bartos
Southwest Florida Water Management District
George Isiminger, PE
Port Manatee
Roger Tucker
Tampa Bay Regional Planning Council
Fred Webb
Hillsborough Community College