There is a lot of focus on CO2 when it comes to public awareness about climate change. Apart from CO2 though not being the only factor contributing to it, there is also very little awareness of the effects of air pollution on terrestrial environments, such as lakes, rivers, fauna and flora. The Cary Institute of Ecosystem Studies and The Nature Conservancy in the US has produced the first major research analysing large-scale effects that four air pollutants are having across a broad range of habitat types. And the outlook is not good: the report, “Threats From Above: Air Pollution Impacts on Ecosystems and Biological Diversity in the Eastern United States” (to which over 32 experts contributed), has found that air pollution is degrading every major ecosystem type in the that area.
The four pollutants assessed were sulfur, nitrogen, mercury, and ground-level ozone, largely originating from smokestacks, tailpipes, and (of course!) agricultural operations. While initially airborne, these pollutants eventually return to the earth surface, where they contaminate the soil and water. They often travel long distances before reaching the ground; the eastern United States for example is located downwind from large industrial and urban pollution sources, which makes it receives the highest levels of deposited air pollution in North America.
This is bad news for vulnerable wildlife, forest productivity, soil health, water resources, and ultimately, economies. Mercury contamination for example results in fish being unsafe to eat. Acidification kills fish and strips nutrients from soils. Excess nitrogen pollutes estuaries, to the detriment of coastal fisheries. And ground-level ozone reduces plant growth, a threat to forestry and agriculture.
New air quality standards are critical to protecting natural resources. At the heart of the report is a call to action. Currently, U.S. air quality standards are determined by direct impacts to human health, with regulations targeting emission levels; they do not take into account where airborne pollution is actually deposited in the landscape or how this pollution compromises our soil and water resources and resident plants and animals.
To safeguard ecosystem health, a new way of thinking about air pollution is needed, one that moves beyond measuring what is put up in the air, and captures actual impacts to natural areas, wildlife, and the services they provide.
The authors of the report urge U.S. policymakers to establish air quality standards that are based on ‘critical loads’. This is defined as the maximum level of deposited pollution that ecosystems can tolerate before harmful effects occur. By establishing thresholds, pollutants can be regulated in a way that preserves functioning ecosystems. In some areas, such as Rocky Mountain National Park, federal agencies have already adopted this approach to evaluate the threat from air pollution. It is also being used to regulate air pollution throughout Europe.
Establishing ‘critical loads’ will require renewed investment in monitoring programs for air pollution and the ecosystems it affects. While there may be initial costs to ramping up monitoring efforts, the alternatives such as fishless lakes, dieing forests and the yet unknown effects of biodiversity loss will certainly result in much higher future economic costs. And while the material argument unfortunately is the primary one in our world, there are more intangible consequences too, such as those for our bond to nature or ethical concerns in regards to our impact on other species.
Air pollution is a complex problem. Emissions of sulfur dioxide (SO2) and nitrogen oxide (NOx) gases from smokestacks and vehicles react in the atmosphere to form sulfate (SO4) and nitrate (NO3) particles as well as sulfuric and nitric acids in clouds and rain. Mercury (Hg) is also emitted to the atmosphere from coal burning and incinerators. Agricultural activities contribute to the nitrogen pollution problem by releasing ammonia (NH3). All of these gases, particles and dissolved chemicals can be deposited to natural ecosystems downwind of the sources. Nitrogen can accumulate in ecosystems and cause nutrient imbalances, while acid precipitation can strip important nutrients such as calcium (Ca) from the soil and mobilize toxic metals such as aluminum (Al). Acid and aluminum harm trees in the forest and fish and other aquatic animals in streams and lakes.
View the report at http://www.ecostudies.org/Threats_from_Above.pdf.
This post is based on an article published by Physorg.com.