Whatever happened to acid rain? Remember back in the '80s when you couldn't pick up a newspaper without reading about fish kills, dying trees, crumbling historic statues and buildings and other victims of the vinegary precipitation? Those stories gave way to stories about global warming and high levels of mercury in fish. Does that mean acid rain is a thing of the past? A non-issue? Far from it.

Acid rain is the by-product of the industrial revolution. It is just what the term - which, by the way, was coined by British chemist Robert Angus Smith way back in 1852 - says it is, rain whose pH is lower than normal due to mixing with sulfur and nitrogen compounds emitted in the air primarily by power plants fueled by coal, oil and gas but also by cars and other polluters that burn fossil fuels. It was of particular concern in the Midwest and Northeast, where the chemicals blew in on prevailing winds from dirty coal-burning plants located further to the south and west. Rain water samples taken at the Hubbard Brook Experimental Forest in New Hampshire in 1963 showed pH levels of 4.05 to 4.1 - 100 times lower than normal. (Natural rain water has a pH of 5.2). The trees in the area looked like it had rained bleach. Since we are still using electricity and driving cars, it is safe to say that acid rain continues to be a factor in our lives, albeit not as big a factor as it was 10 years ago before restrictions on power plants were implemented as part of the 1990 Clean Air Act.

The Environmental Protection Agency is proud of its Acid Rain Program, mandated by the Act, which requires coal-fired power plants to lower their emissions of sulfur dioxide (SO2) and nitrogen oxide (NOx) - two of the main by-products of the burning process. (Fossil fuel-burning power plants are responsible for 63 percent of the SO2 and 22 percent of the NOx emitted each year in the U.S.). Phase one of the two-phase program was initiated in 1995 with restraints placed on the largest and dirtiest plants. Five years later, smaller plants were also added, (the program affected a total of about 3,000 facilities) and the total amount of SO2 that could be emitted in the U.S. on an annual basis was limited to 8.95 million tons. By 2010, the amount of SO2 allowed to enter the atmosphere will be half of what was being emitted in 1980. No cap was placed on NOx emissions. (Carbon dioxide, which is related to global warming but not to acid rain, is another harmful component of power plant emissions.)

The program also allowed the plants to engage in "emissions trading," an activity that takes place not on Wall Street but in the offices of the plant executives. Sources are given "allowances" each year, not for cleaning up their rooms and emptying the trash, but to make it easier for them to pay for the technology required to keep their emissions low. Each allowance is worth one ton of SO2. The plants can buy, sell or hang onto their allowances for future use. A company that owns a plant with high emissions, could, for example, continue to run the plant without lowering its emissions by buying an allowance from a company with one or more plants with low emissions.

According to the EPA, the amount of NOx emissions decreased from six million tons in 1997 to 4.5 million in 2002, despite the fact that no limits were placed on emissions. Total emissions of both pollutants dropped from 5.6 million in 1990 to 4.1 million in 2000, and Michigan was listed as one of the states that experienced the largest reductions in "wet nitrogen deposits."

So, what does all that mean? It should mean that such creatures as salamanders, rainbow trout, frogs, crayfish, all of which die when the pH in their wetland habitats falls below 4.5, can rest a little easier. It should also mean that agricultural yields should increase and the trees in New Hampshire and other areas most heavily impacted, including Michigan, should begin to make a comeback, since acid rain affects plant growth. It should also mean a decrease in mercury contamination in fish, since low pH can make more methyl mercury available in surface water.

However, scientists caution that decades of acidic rainfall have caused changes to soil composition and aquatic ecosystems in certain areas that will make recovery very difficult, including calcium and magnesium depletion (calcium has declined as much as 50 percent in the soil at Hubbard since testing began.); an accumulation of sulfur and nitrogen in forest soils; and higher than normal levels of dissolved inorganic aluminum, which interferes with a tree's ability to absorb water and nutrients and results in reduced diversity of aquatic species.

A study by Cornell University researchers in 2002 indicated a link between acid rain and the decline of wood thrushes in the Northeast. They believe that it may be the result of reduced calcium levels in the soil. An Aug. 13, 2002, story in the "National Geographic News" website suggested that the "supplementary calcium-rich foods that female wood thrushes depend on - snail shells, isopods such as pill bugs, millipedes and earthworms - may be in short supply" in "areas where acid rain is most severe," which could cause egg shells to be "thin, brittle and porous." High levels of aluminum, cadmium and lead that are typically found in the soil in those areas could also have a detrimental affect, according to the article.

We're making progress in terms of cutting back emissions, but is it too little too late? I would like to know why, when the problem was discovered more than 150 years ago, we are only now getting around to doing something about it. Why, when we have the technology to produce fuel efficient cars and alternative sources of energy, aren't we making it easier for people to manufacture and buy those products by providing tax breaks and other incentives?

I don't have the answers, but I'll leave you to consider the questions. And don't forget to turn out the lights when you leave the room. Every little bit helps.

The information in this column was compiled from various sources, including the EPA and US PIRG websites. For more information about this topic, search the web under "acid rain."

You can email Karen at karen@lakeshoreguardian.com.