ANALYSIS OF NEUTRALIZATION OF ACIDIC PREC IPITATION WITH SOIL

The phenomena of environmental acidification by acidic precipitation i s a global environmental problem. In this study, in order to assess th e effect of acidic precipitation on water quality in rivers and lakes, a new method for estimating the neutralization mechanisms of acidic p recipitation with soil is proposed. The method was based on the chemic al equilibrium analysis of the relationship between the metal ions rel eased from soil and the pH value in the aqueous phase. The mechanisms of neutralization by soil are generally listed as; calcium carbonate b uffer, cation exchange buffer, aluminum buffer, and anion exchange buf fer. However, it is recognized that cation exchange reaction and disso lution of aluminum from the soil are the principal contributors to neu tralization of acid precipitation with soil. Many cations take part in neutralization reaction. To represent the multiple components in a lu mp, a new function is proposed. It is estimated from the pH value of a n acid solution before and after equilibration with soils. To estimate the neutralization reaction, a relationship between pH and concentrat ions of metal ions released from soil and of metal ions derived from n eutral soils was proposed. Four samples of soil were used for equilibr ation experiments between the acid solutions and the soil materials. T he results of the analyses revealed that the carbon dioxide in gaseous phase and cations derived from neutral soils contribute strongly to t he neutralization of the acidified precipitation during contact with t he soil materials.