Model radioisotope experiments on the influence of acid rain on 65Zn binding with humic acid

Acid rain formed first of all from sulphur oxide emitted by natural and anthropogenic sources, may change the biological equilibrium and the metal stoppage in the soil. The model experiments were performed to determine the influence of acid rain on zinc bond with humic acid (HA). The samples were prepared in glass columns with quartz sand and overlaid HA or HA+65Zn radioisotope that simulates natural conditions. Then, solutions of H2SO4 were introduced into the sand HA layer. Zinc was washed with diluted (10 4 10 3 M) sulphuric acid as the simulation of acid rain. The recovery of injected radiotracer ions in eluates was found to depend on pH of simulated acid rain. The results help to evaluate the migration behaviour of zinc in the presence of HA and H2SO4. The model studies illustrate the considerable influence of sulphuric acid on chemical degradation of HA.