Department of Ecological Science, Faculty of Earth and Life Sciences, VU University, Amsterdam, The Netherlands.
Environ Toxicol Chem. 2013 Dec;32(12):2746-54. doi: 10.1002/etc.2353. Epub 2013 Oct 17.
To improve our understanding of metal bioavailability to soil-living invertebrates, the effect of porewater composition on the toxicodynamics of copper and cadmium in Folsomia candida (Collembola) was investigated. Assuming that porewater is the main exposure route, F. candida was exposed to simulated soil solutions of different composition. Toxicity of copper was slightly lower in a calcium-only solution than in a multication solution. With increasing copper concentrations from 0.005 mM to 1.37 mM, internal copper concentrations similarly increased in both exposure solutions, suggesting that a single cation nutrient solution is suitable for testing F. candida. In the second experiment, animals were exposed for 7 d to copper and cadmium in simplified soil solutions with different calcium (0.2 mM, 0.8 mM, 3.2 mM, 12.8 mM) and pH (5.0, 6.0, 7.0) levels. The median lethal concentration (LC50) values decreased with time in both the calcium and pH series. A hormetic-type effect was observed for copper in the second test, as well as in the calcium-only solution in the first experiment. Because of stronger hormesis, LC50s for copper were higher at lower calcium concentrations. For cadmium, LC50 values were higher at higher calcium concentrations, suggesting competition of calcium with the free cadmium ion. Toxicity of cadmium increased with decreasing pH, while copper was more toxic at intermediate pH. The results show that a toxicodynamics approach can help to improve the interpretation of metal toxicity to soil invertebrates, taking into account soil solution properties.
为了提高我们对土壤生物体内金属生物利用度的理解，本研究调查了孔隙水组成对 Folsomia candida（弹尾目）中铜和镉毒性动力学的影响。假设孔隙水是主要的暴露途径，F. candida 被暴露于不同组成的模拟土壤溶液中。与多阳离子溶液相比，仅含有钙离子的溶液中铜的毒性略低。随着铜浓度从 0.005 mM 增加到 1.37 mM，两种暴露溶液中体内铜浓度均相似增加，表明单一阳离子营养溶液适合用于测试 F. candida。在第二个实验中，动物在不同钙离子（0.2 mM、0.8 mM、3.2 mM、12.8 mM）和 pH（5.0、6.0、7.0）水平的简化土壤溶液中暴露于铜和镉 7 天。LC50 值在钙离子和 pH 系列中均随时间而降低。在第二个实验以及第一个实验中的仅钙离子溶液中，观察到铜的兴奋效应。由于更强的兴奋效应，在较低的钙离子浓度下，LC50 对于铜更高。对于镉，LC50 值在较高的钙离子浓度下更高，表明钙离子与游离镉离子的竞争。镉的毒性随 pH 值降低而增加，而铜在中等 pH 值时毒性更强。结果表明，毒性动力学方法可以帮助提高对土壤无脊椎动物金属毒性的解释，同时考虑到土壤溶液特性。
