Characteristics and Law of Lead Release from Red Soils Under the Influence of Simulated Acid Rain

Acid rain can induce soils to release heavy metals and causes damages to plants,degrades soils.Red soils in the south of China are hypersensitive to acid rain.In order to evaluate the harm caused by acid rain to red soil environment,a soil leaching column experiment was designed to investigate the release of lead from red soils under the influence of simulated acid rain.The results showed that acid rain could accelerate the release of lead from red soils.The influence of acid rain on the release of lead from red soils appeared some regularity,at the initial stage of the leaching experiment,the releases of lead varied with different red soils,but after the middle stage,the release of lead in all tested red soils increased with the increase of leaching amount.Acid rain had an obvious effect on the release of lead,which varied with the distinctness of the tested soils,suggesting that the release of lead was affected by the ability of soils to amortize acidification.After simulating rainfall of 9 150~10 650 mm,compared with the control,the cumulative release amount of lead increased 10.64%~99.19% under acid rain of pH4.5,and reached 17.02%~483.15% under acid rain of pH3.5.The cumulative release of lead could be described with quadratic model,and the quadratic model for the average cumulative release of lead from the tested soils was:Q=-2.5335+0.0266H+6.8677×10-7H2.