Cadmium, mercury and lead leaching study on soils derived from volcanic ashes

Abstract

The leaching of cadmium, lead and mercury was studied on undisturbed soil samples of soil derived from volcanic ashes. The soil samples were collected from two depths 0-15 cm and 15-30 cm from an Andisol (Valdivia soil series) and from an Ultisol (Los Ulmos soil series) with PVC cylinders with a soil volume content of 396 cm³. Solutions containing Cd, Pb and Hg of known volume and concentration were applied to totals of 2.3, 0.23, and 23 mg L^-1 for Cd, Hg and Pb, respectively. Applications were done each seven day until a total of thirteen. From each application a percolate was collected and the heavy metal content was analyzed by atomic spectrometry. The soils evaluated presented over 96 % of Cd, Hg and Pb retention of the amount applied, which was reflected on the low amount leached from the total metals applied. The retention varied with the soil type and the soil depth, presenting the Valdivia soil at 15-30 cm depth the higher retention but the same soil the lowest retention at 0-15 cm depth. The red clay soil Los Ulmos presented an intermedium retention and a low variation between both soil depth evaluated. From the heavy metals evaluated cadmium presented the high leached amount from the total applied.