Department of Biology and the Centre for Environmental and Marine Studies, University of Aveiro, Portugal.
Department of Biology and the Centre for Environmental and Marine Studies, University of Aveiro, Portugal.
Ecotoxicol Environ Saf. 2017 Nov;145:142-149. doi: 10.1016/j.ecoenv.2017.07.008. Epub 2017 Jul 18.
mMarine and estuarine ecosystems are highly productive areas that often act as a final sink for several pollutants, such as cadmium. Environmental conditions in these habitats can affect metal speciation, as well as its uptake and depuration by living organisms. The aim of this study was to assess cadmium uptake and depuration rates in the euryhaline calanoid copepod Acartia tonsa under different pH, salinity and temperature conditions. Cadmium speciation did not vary with changing pH or temperature, but varied with salinity. Free Cd ion activity increased with decreasing salinities resulting in increased cadmium concentrations in A. tonsa. However, uptake rate, derived using free Cd ion activity, showed no significant differences at different salinities indicating a simultaneous combined effect of Cd speciation and metabolic rates for osmoregulation. Cadmium concentration in A. tonsa and uptake rate increased with increasing pH, showing a peak at the intermediate pH of 7.5, while depuration rate fluctuated, thus suggesting that both parameters are mediated by metabolic processes (to maintain homeostasis at pH levels lower than normal) and ion competition at membrane binding sites. Cadmium concentration in A. tonsa, uptake and depuration rates increased with increasing temperature, a trend that can be attributed to an increase in metabolic energy demand at higher temperatures. The present study shows that cadmium uptake and depuration rates in the marine copepod A. tonsa is mostly affected by biological processes, mainly driven by metabolic mechanisms, and to a lesser extent by metal speciation in the exposure medium.
海洋和河口生态系统是高生产力区域，通常是多种污染物（如镉）的最终汇。这些生境中的环境条件会影响金属的形态，以及生物体对其的吸收和净化。本研究旨在评估不同 pH 值、盐度和温度条件下广盐桡足类桡足类动物 A. tonsa 对镉的吸收和净化速率。镉的形态没有随 pH 值或温度的变化而变化，但随盐度而变化。自由 Cd 离子活性随盐度的降低而增加，导致 A. tonsa 中的镉浓度增加。然而，利用自由 Cd 离子活性得出的吸收速率在不同盐度下没有显著差异，表明 Cd 形态和渗透压调节的代谢率同时存在综合效应。A. tonsa 中的镉浓度和吸收速率随 pH 值的增加而增加，在 pH 值为 7.5 的中间值达到峰值，而净化速率则波动不定，这表明这两个参数都受到代谢过程（在低于正常水平的 pH 值下维持体内平衡）和膜结合部位离子竞争的调节。A. tonsa 中的镉浓度、吸收和净化速率随温度的升高而增加，这种趋势可归因于高温下代谢能量需求的增加。本研究表明，海洋桡足类动物 A. tonsa 对镉的吸收和净化速率主要受生物过程的影响，主要由代谢机制驱动，其次是暴露介质中的金属形态。
