Changing River Chemistry Affects Eastern U.S. Water Supplies
"25+ years of records show two-thirds of region’s rivers are now alkaline – a legacy of acid rain, researchers say.
COLLEGE PARK, Md – Acid rain and other unintended side effects of human activities are changing the basic chemistry of many rivers in the Eastern U.S., with potentially major consequences for urban water supplies and aquatic ecosystems, a University of Maryland-led study has found.
In the first survey of its kind, researchers looked at long-term records of alkalinity trends in 97 streams and rivers from Florida to New Hampshire. Over time spans of 25 to 60 years, two-thirds of the rivers had become significantly more alkaline and none had become more acidic.
Alkalinity is a measure of water’s ability to neutralize acid. In excess, it can cause ammonia toxicity and algal blooms, altering water quality and harming aquatic life. Increasing alkalinity hardens drinking water, makes wastewater disposal more difficult, and exacerbates the salinization of fresh water.
Paradoxically, higher acid levels in rain, soil and water, caused by human activity, are major triggers for these changes in river chemistry, said associate professor Sujay Kaushal of the University of Maryland. Kaushal, a geologist, is the lead author of a paper about the study, published August 26 in the online edition of the peer-reviewed journal Environmental Science and Technology.
The researchers hypothesize that acid rain, a by-product of fossil fuel burning, acidic mining runoff and agricultural fertilizers speed up the dissolving of surfaces that are naturally high in alkaline minerals. In a process known as chemical weathering, the acid eats away at limestone, other carbonate rocks, and even concrete sidewalks, dissolving alkaline particles that wash off into streams and rivers."
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http://cmns.umd.edu/news-events/features/1177
