Prevention Values for Copper (Low Tier Approach) in Subtropical Acidic Soils

Abstract

Copper is a trace element in plants and animals whose importance can be understood due to its role in different essential metabolic processes. Anthropogenic activities such as agriculture and mining are potential sources of pollution due to the emission of copper into the environment. Brazilian legislation ties soil quality to guideline values, among which the Prevention Value indicates the critical environmental limit for trace elements. The aim of this study was to obtain PVs for copper for two subtropical soils (Cambisol and Nitisol), given that the pedological richness was not considered when deriving the PVs contained in the federal normative. Reproduction assays followed ISO guidelines with the earthworm species Eisenia andrei and Perionyx excavatus, the enchytraeids Enchytraeus crypticus and E. bigeminus and the springtails Folsomia candida and Proisotoma minuta. Results showed that the sensitivity of the organisms was greater in Cambisol. The most sensitive species were the earthworms, especially P. excavatus (EC50 = 67.83 in Cambisol; EC50 = 264.96 in Nitisol). The springtails, on the other hand, were the least sensitive to contamination. These findings reinforce the need to include organisms from different ecological groups in ecotoxicological assessments. It was also observed that the PV adopted in federal legislation (= 60 mg kg-1) is in fact protective for the species and soils we evaluated, since the PVs we obtained based on the EC50 were 346.74 mg kg-1 in Nitisol and 134.05 mg kg-1 in Cambisol. It is important to note that our results do not exclude the need for evaluations with other subtropical soils, given the influence of their properties on the toxicity and bioavailability of copper to soil organisms.