Use of physical-chemical and ecotoxicological parameters in the evaluation of remediation of soils degraded by mining activities

Abstract

In the remediation of soils potentially contaminated by mining activities, it is important to consider environmentally sustainable technologies, applicable to large areas. The in situ remediation strategy that consists in the addition of organic, or inorganic, amendments, allows the rehabilitation of these soils, improving soil characteristics and immobilizing contaminants, turning them into less bioavailable forms. The recovery of this type of materials meets the European goals established for the disposal of waste in landfills, considering that it is essential to reduce the quantities deposited in landfills and increase their recovery, promoting their integration into the production system. This study aimed to evaluate the sustainable use of materials from the pulp and paper industry (biomass ashes and biological sludge) in improving the quality of soils contaminated by mining activities in the Iberian Pyrite Belt (IPB: Aljustrel, Lousal and São Domingos Mines), at two different times: 1 and 25 months after application of the materials. Physicochemical and ecotoxicological parameters were used in that evaluation. The results suggested that the tested amendments allowed a clear improvement in the physicochemical properties of the soils, essential for the recovery of their characteristics and functions, and a reduction of the toxic response of several test organisms, Pseudokirchneriella subcapitata, Thamnocephalus platyurus and Daphnia magna, when exposed to the soil-water extracts of amended soils.