Acidic precipitation: considerations for an air-quality standard
Acidic precipitation, wet or frozen deposition with a hydrogen ion concentration greatern than 2.5 ..mu..eq l/sup -1/ is a significant air pollution problem in the United States. The chief anions accounting for the hydrogen ions in rainfall are nitrate and sulfate. Agricultural systems are more likely to derive net nutritional benefits from increasing inputs of acidic rain than are forest systems when soils alone are considered. Agricultural soils may benefit because of the high N and S requirements of agricultural plants. Detrimental effects to forest soils may result if atmospheric H/sup +/ inputs significantly add to or exceed H/sup +/ production by soils. Acidification of fresh waters of southern Scandinavia, southwestern Scotland, southeastern Canada, and northeastern United States is caused by acid deposition. Areas of these regions in which this acidification occurs have in common, highly acidic precipitation with volume weighted mean annual H/sup +/ concentrations of 25 ..mu..eq l/sup -1/ or higher and slow weathering granitic or precambrian bedrock with thin soils deficient in minerals which would provide buffer capacity. Biological effects of acidification of fresh waters are detectable below pH 6.0. As lake and stream pH levels decrease below pH. 6.0, many species of plants, invertebrates, and vertebrates are progressively eliminated. Generally, fisheries are impacted below pH 5.0 and are completely destroyed below pH 4.8. There are few studies that document effects of acidic precipitation on terrestrial vegetation to establish an air quality standard. It must be demonstrated that current levels of precipitation acidity alone significantly injure terrestrial vegetation. In terms of documented damanges, current research indicates that establishing a standard for precipitation for the volume weighted annual H/sup +/ concentration at 25 ..mu..eq l/sup -1/ may protect the most sensitive areas from permanent lake acidification.
- Research Organization:
- Brookhaven National Lab., Upton, NY (USA); Manhattan Coll., New York (USA). Lab. for Plant Morphogenesis; Illinois State Water Survey, Urbana (USA); Oak Ridge National Lab., TN (USA)
- DOE Contract Number:
- AC02-76CH00016
- OSTI ID:
- 6580616
- Report Number(s):
- BNL-29031; CONF-8009137-1
- Resource Relation:
- Conference: APCA conference on the proposed SO/sub x/ and particulate standards, Atlanta, GA, USA, 16 Sep 1980
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ACID RAIN
ENVIRONMENTAL EFFECTS
POLLUTION REGULATIONS
AIR POLLUTION
AQUATIC ECOSYSTEMS
ATMOSPHERIC PRECIPITATIONS
BIOLOGICAL EFFECTS
NITROGEN
PH VALUE
PLANTS
RECOMMENDATIONS
SOILS
STANDARDS
SULFUR
TERRESTRIAL ECOSYSTEMS
CONTAMINATION REGULATIONS
ECOSYSTEMS
ELEMENTS
NONMETALS
POLLUTION
RAIN
REGULATIONS
500200* - Environment
Atmospheric- Chemicals Monitoring & Transport- (-1989)
500600 - Environment
Atmospheric- Regulations- (-1989)