Effects of Atmospheric Pollutants on Soils

Abstract

The effects of two types of atmospheric pollutants on soils, acid precipitation and metals, are considered. Potential acid precipitation effects include soil acidification, increased loss of plant nutrients, accelerated weathering of mineral components, decreased rates of organic matter decay, changes in soil organism populations, mobilization of aluminum ions, and reduction in cation exchange capacity. Soils that are poorly buffered, i.e., have low cation exchange capacity due to low clay and organic matter contents, are most likely to undergo appreciable change due to acid inputs. Acid precipitation inputs experienced thus far are generally low compared to the effects of agricultural fertilization and liming practices on soil pH.

Results of field experimentation have not shown serious deleterious effects of acid precipitation on productivity or soil biota. The reaction of soils to acid inputs is complex and dependent on numerous soil parameters, such as type of clay present, base saturation, presence of easily weatherable minerals, and upon the ionic composition of the precipitation.

Soils are efficient collectors of metallic ions. Damaging levels of metal contamination of soils reported thus far are confined to urban areas and regions around point sources, such as smelters. Since metals are retained over long periods, recovery from metal contamination is slow.