Ecotoxicity test as an aid in the determination of copper guideline values in soils

ABSTRACT: The process of identifying a contaminated area involves a preliminary assessment consisting of chemical analysis and comparison with guideline values. In Brazil, these values are included in the CONAMA Resolution no. 420/2009, based on chemical analysis and phytotoxicity. The objective of this research was to evaluate the ecotoxicity of copper in two natural soils in the state of Rio de Janeiro, a Haplic Planosol (sandy) and a Red-Yellow Argisol (medium texture), to verify if the values established by the legislation offer protection to the soil fauna. Lethality and reproduction tests were performed with Eisenia andrei worms and Folsomia candida springtails. Results indicated copper values in Planosol as LC50 435 mg kg 1 and EC50 29 mg kg 1 for E. Andrei and LC10 137 mg kg 1 and EC50 117 mg kg 1 for F. candida. In Argisol, these results were LC50 690 mg kg 1 and EC50 61 mg kg 1 for E. andrei, and LC10 42 mg kg 1 and EC50 138 mg kg 1 for F. candida. Values reported are lower than the research value (200 mg kg-1) established by the CONAMA resolution 420/09, indicating that concentrations lower than the limit values may affect these organisms, depending on the type of soil. Worms were more sensitive than springtails to copper contamination, and sandy soil was more susceptible to ecotoxicity due to copper contamination, probably due to the greater bioavailability of the metal. Results of such ecotoxicity tests should be considered in the development of soil guideline values.

摘要：污染区域识别流程包含以化学分析与指导值对比为核心的初步评估环节。在巴西，相关污染指导值纳入《巴西国家环境委员会（CONAMA）第420/2009号决议》，该决议基于化学分析与植物毒性制定。本研究旨在评估里约热内卢州两种天然土壤中铜的生态毒性，分别为砂质简育薄层土（Haplic Planosol）与中质地红黄黏磐土（Red-Yellow Argisol），以验证现行立法设定的限值能否有效保护土壤动物群落。本研究采用安德爱胜蚓（Eisenia andrei）与白符跳虫（Folsomia candida）分别开展致死性与繁殖试验。结果显示，砂质简育薄层土中，铜对安德爱胜蚓的半数致死浓度（LC₅₀）为435 mg·kg⁻¹、半数效应浓度（EC₅₀）为29 mg·kg⁻¹；对白符跳虫的10%致死浓度（LC₁₀）为137 mg·kg⁻¹、半数效应浓度为117 mg·kg⁻¹。在红黄黏磐土中，铜对安德爱胜蚓的LC₅₀为690 mg·kg⁻¹、EC₅₀为61 mg·kg⁻¹；对白符跳虫的LC₁₀为42 mg·kg⁻¹、EC₅₀为138 mg·kg⁻¹。本次试验测得的铜浓度值均低于CONAMA第420/2009号决议设定的200 mg·kg⁻¹标准限值，这表明低于该限值的铜浓度可能对上述土壤生物造成影响，且影响效果取决于土壤类型。安德爱胜蚓相较于白符跳虫对铜污染更为敏感，砂质土壤更易受到铜污染引发的生态毒性影响，这可能与该土壤中铜的生物有效性更高有关。在制定土壤环境指导值时，应纳入此类生态毒性试验的研究结果。