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Mercury levels dropping, but still widespread

September 10, 2015
By SHAUN KITTLE - Outdoors Writer (skittle@adirondackdailyenterprise.com) , Lake Placid News

Adirondack loons aren't out of the woods yet.

Nina Schoch, coordinator of the Biodiversity Research Institute's Adirondack Center for Loon Conservation, said the iconic Adirondack birds are still exhibiting the detrimental effects of mercury pollution, although some of her colleagues say the worst of it might be over.

BRI's loon mercury project has been ongoing since 1998. It started with about 50 birds, and now they've banded more than 300 birds and taken samples from more than 400. Sometimes BRI scientists sample chicks that they don't band.

"We've been monitoring some of these birds for over a decade, and we're really getting to understand more than just the mercury levels," Schoch said. "We're also looking at population measurements, from how birds change territories and change mates, and addressing conservation concerns that are affecting individual birds and the population as a whole."

Schoch was just referring to BRI's work in the Adirondacks. In North America, the organization has banded more than 5,000 loons.

There are several different forms of mercury, like gaseous, elemental and methyl. That last one is the killer.

In the early 1900s, the bulk of mercury pollution came from power plants, particularly those that burn coal.

Elemental mercury from the Midwest enters the jetstream with a smorgasbord of other chemicals like sulfur dioxide and nitrogen oxides, and is deposited in the Adirondacks in the form of acid rain.

The midwestern states aren't solely to blame, though. Mercury pollution in the Adirondacks can come from power production sources around the world, and gold mining operations are also a major contributor.

Regardless of the source, the result is the same. Mercury that ends up in an acidic waterbody is converted to methyl mercury by bacteria. Since many Adirondack waterbodies are acidic, the region is essentially dotted with methyl mercury factories.

Schoch said there are more acidic lakes in the southwest portion of the Park.

"They're getting more lake-effect snow, so the amount of rainfall and snow are higher there," Schoch said. "We're just starting to look at some of the birds over time, and so far what we're finding is it (mercury levels) varies from place to place and individual to individual."

Unlike elemental mercury, methyl mercury is a bioaccumulator, so it stays with the organism that ingests it.

Picture a lake with a robust population of little fish. As the fish feed, they also ingest methyl mercury. A loon comes along, and it eats a bunch of those little fish. The methyl mercury that was in those little fishes is now part of the loon.

Loons live 20 to 30 years, giving them plenty of time to accumulate mercury.

The result is catastrophic to the animal. It causes them to be more lethargic and depressed, so adults don't defend their territories or eggs as well. A chick might not have the energy to climb onto its parent's back to keep safe from predators or to keep warm.

"What we're seeing further east in North America, like in New Brunswick and Nova Scotia, the population models there indicate that the birds there aren't reproducing enough to maintain a steady population," Schoch said. "We don't want to see that here."

Charles Driscoll, an environmental systems engineering professor with Syracuse University, studies things like how mercury moves in the atmosphere, watersheds and soil, and he also works with scientists from entities like the state Department of Environmental Conservation and Cornell University to study mercury concentrations in Adirondack fish.

A lot of the work is still underway and no conclusions have been drawn, but Driscoll said the research thus far indicates that the mercury situation in the Adirondacks is a mixed bag. Some lakes are showing a decrease while a few are still showing an increase.

Despite that, there is evidence that gives him hope.

"We know that mercury gets from the land to the water as it's carried through organic matter," Driscoll said. "At a site where we have long-term measurements, we know that the amount of mercury relative to the amount of organic matter is decreasing and that, to me, is good news because that suggests that the inputs are getting lower. There's less mercury that's being transferred with this organic matter to the aquatic systems and the fish, but don't get me wrong, the Adirondacks are still a hotspot for mercury."

Driscoll explained that soils are sinks for elemental mercury, meaning the chemical accumulates there for some time before it leaches out.

He said the increased leaching of organic matter documented at some sites could explain an increase in mercury in nearby waterbodies. That poses a risk to species beyond the ones that call those sites home.

"Methyl mercury goes from relatively low concentrations in water up to relatively high concentrations in fish as it moves up the food chain," Driscoll said. "It's concentrated by a factor of a million to 10 million, so our exposure to mercury is virtually all through fish consumption."

BRI also studies mercury in songbirds on the east coast.

Amy Sauer began working with BRI's loon project in 2004. In 2008 she left to get her Ph.D. and in 2013 she launched a five-year project to study the affects of mercury on songbirds in New York.

Her approach targets species determined most at risk, but her goal is also to collect as much data on as many species as possible. Birds have been banded and sampled annually in three regions: the Adirondacks, Catskills and Long Island.

There are also "roaming sites" that are part of the project, including the Tug Hill Plateau, the Montezuma Wildlife Refuge and the Seneca region. Sauer said the Finger Lakes and Western New York are on the list of upcoming regions to visit.

Sauer said she was curious about how mercury is deposited across the landscape. So far, her findings are consistent with what Schoch and Driscoll have found.

"We've found that, when you compare different habitat types, certain habitat types do have higher mercury levels," Sauer said. "Wetland habitats tend to have higher mercury levels than upland forests. It's because they're very acidic, low-oxygen environments so you have a lot of mercury being methylated there. Consequently, there's a lot of methyl mercury available in those habitats and that gets taken up into the food web."

Forest species also contain higher-than-average mercury levels, but the highest levels have been found in wetland species, so a lot of Sauer's work has focused on songbirds like palm warblers, Lincoln sparrows, common yellowthroats, olive-sided flycatchers and rusty blackbirds. High levels of mercury have been found in blood samples from all of those species.

The effects of mercury on songbirds are similar to its effect on loons, things like lower reproductive success, lower chick survival, feather asymmetry and disruption to the endocrine and immune systems.

Sauer said the mountain of data her team has accumulated will eventually be used to push for legislation that curbs mercury emissions.

"We're using the loons and the songbirds as indicators of the health of both the aquatic and the terrestrial environment," Sauer said. "Because of their level in the food web, they do serve as very good indicators, so it plays into the health of a lot of other species as well."

 
 

 

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