Study of the concentration of toxic trace elements of sludge deposits, soils and plants in Mina La Solana, Almería (Spain).

Abstract

Caro-Moreno, D., Jiménez-Cantizano, F.A. 2013. Study of the concentration of toxic trace elements of sludge deposits, soils and plants in Mina La Solana, Almería (Spain). Ecosistemas 22(3):101-110. Doi.: 10.7818/ECOS.2013.22-3.14.

This work presents a study of the concentration of toxic trace elements in abandoned sludge deposits (tailings) by mining in Almeria (Spain), soils and plants that colonize and represent a way to incorporate those elements in the food chain. The old mining industry left a number of abandoned facilities in different parts of Andalusia, with tailings standing out. They were generated in the flotation process, and usually deposited and left on streambeds. Tailings composition vary depending on the type of ore and treatment additives, but usually the contents of heavy metals are high, because recovery was not very good in the mineral processing technique used in the early 20th century facilities. In this study we analyze the case of Mina La Solana tailings, located in Almócita (Almería, SE Spain). We carried out a geochemical characterization of trace element content. Furthermore, we also studied the geochemical trace element content in plants that were rooted in the tailings. The results show that tailings have high Pb content (average concentration 6800 ppm) and Zn (average concentration 22 000 ppm). These elements are not mobile soluble fractions; leaching tests give very low concentration levels (≤ 10 ppm Pb and ≤ 2 ppm Zn) in water. We found high concentrations of the same elements in plants, with a value of up to 210 ppm Pb and 1300 ppm Zn. This demonstrates the ability of plants to alter the mobility of the elements present in the substrate where they are rooted and thus providing a transfer to the food chain through feeding species.