Copper prevention values in Brazilian subtropical soils

The Brazilian National Environmental Council (CONAMA) Resolution 420/2009 establishes soil quality guideline values for copper, as the prevention value (PV). It defines the maximum concentrations of chemical substances permitted in the soil. Thus, the aim of the present research was to evaluate the effectiveness of the copper PV adopted at the national level by conducting exposure assays with enchytraeids (Enchytraeus crypticus, Enchytraeus bigeminus and Enchytraeus dudichi) and springtails (Folsomia candida, Proisotoma minuta and Sinella curviseta) in two Brazilian subtropical soils: a Latosol and an Argisol. Results revealed that copper reduces the reproductive capacity of all organisms as its concentration increases in the evaluated soils. Argisol presented the lowest effective concentration of 20% (EC₂₀) and 50% (EC₅₀) in species reproduction for all organisms evaluated. The most sensitive organism was the enchytraeid E. bigeminus, with EC₂₀ values of 58 mg kg⁻¹ in Latosol and 30 mg kg⁻¹ in Argisol, and EC₅₀ values of 155 mg kg⁻¹ in Latosol and 91 mg kg⁻¹ in Argisol. Among the springtails, S. curviseta exhibited the highest EC₂₀, with values of 230 mg kg⁻¹ in Latosol and 136 mg kg⁻¹ in Argisol. Conversely, the highest values of EC₅₀ were recorded for the species P. minuta (526 mg kg⁻¹ in Latosol and 415 mg kg⁻¹ in Argisol). Based on the species sensitivity distribution (SSD) approach, the PVs calculated were 172 mg kg⁻¹ for Latosol and 106 mg kg⁻¹ for Argisol, derived from EC₅₀ data. For EC₂₀ data, the PV values calculated were 158 mg kg⁻¹ in Latosol and 100 mg kg⁻¹ in Argisol. By comparing the PV with the Brazilian adopted PV for copper (60 mg kg^-1), it was observed the efficacy of the CONAMA Resolution.