 it a primary stressor?
Tear: I’d also add that, in some places where birds are declining, there has been no obvious habitat change, and many people think of the challenges as being primarily habitat loss, but we certainly know that, for example, some species like the wood thrush within the Adirondack Park, there are fewer wood thrush today than there were 20 years ago. They’re still there, but there aren’t as many. The question is why, and this is part of the disentangling of those different stressors that Dave is referring to.
Q. Is there any relationship between mercury emissions and greenhouse-gas emissions? Is there a climate change connection?
Tear: Well, many of the greenhouse gases like carbon dioxides and other air pollutants — such as nitrogen and sulfur, which cause acid rain, and mercury, which brings us this neurotoxic rain — come from power plants, and all of these air pollutants have negative impacts on our environment. Our research shows that we should be factoring in these ecological impacts when we consider the cost and benefits of regulatory programs such as the recent Mercury and Air Toxics Standards Rule. But so far, estimating the ecological impact of these air pollutants that are coming from similar sources as CO2 has not been done.
Evers: Climate change might also be causing great mercury methylation rates into ecosystems or even remobilizing mercury that was stored in the system. For instance, forest fires have become more predominant because of climate change in some parts of the country — and those forests hold a lot of legacy mercury in their systems, which can be released quite rapidly with a fire. Greater storm intensity and frequency could be increasing deposition of mercury from the global atmospheric pool to landscapes below. Increased wetting and drying cycles could be another factor in greater mercury methylation.
Q. It sounds dire. So what can anyone do?
Tear: First, while we need more research on this, there are definitely landscape and wildlife management actions that might help reduce the amount of mercury embedded in the environment.
Dave mentioned that hotter forest fires that occur for whatever reason can release a great deal more mercury than cooler burns — so using fire management in our forest systems could have a significant impact on the amount of mercury that’s released. How we manage artificial reservoirs is extremely important — if we manage those in a way to make the wetting and drying cycles greater, we might also be increasing the amount of mercury methylation.
Evers: Another example: It makes a lot of sense not to log in a riparian area anyway — and it also makes sense from a mercury standpoint. There is a lot of legacy mercury and even new mercury coming into these forest ecosystems, and the less we disturb that mercury the better. There are studies right now quantifying the mercury effects of logging practices in Oregon.
Q. What else?
Tear: We need greater investment in this country’s mercury monitoring network. A stronger network would help us gather data systematically and also help us know whether current efforts to reduce mercury pollution — like the EPA’s recent Mercury and Air Toxics Rule standard — are enough to improve these areas already damaged by mercury.
We also need continued research on this issue. We’re just beginning to understand the impacts of mercury on both ecological and human health. And we need to support efforts at all levels to reduce mercury — global, regional, and local. Mercury is coming from multiple levels, and no single level will be enough.
Evers: On the importance of a national network — I’ve been fortunate to work with both U.S. Senate and House representatives to introduce bills that would establish the first national mercury monitoring network, which we need from a federal accountability standpoint. But industry also has been supportive of this idea. Industry likes certainty, and a national monitoring network could really help provide a standard playing field for the industry in terms of installing emission protections on their sm