School of Chemistry, University of Wollongong, Wollongong, NSW, Australia; CSIRO Land and Water, Lucas Heights, NSW, Australia; Australian Antarctic Division, Kingston, Tasmania, Australia.
CSIRO Land and Water, Lucas Heights, NSW, Australia.
Environ Pollut. 2018 Nov;242(Pt B):1319-1330. doi: 10.1016/j.envpol.2018.07.110. Epub 2018 Jul 25.
Metal contaminants are rarely present in the environment individually, yet environmental quality guidelines are derived from single-metal toxicity data. Few metal mixture studies have investigated more than binary mixtures and many are at unrealistically high effect concentrations to freshwater organisms. This study investigates the toxicity of five metals (Cd, Cu, Ni, Pb, and Zn) to the Antarctic marine microalgae Phaeocystis antarctica and Cryothecomonas armigera. Two mixtures were tested: (i) an equitoxic mixture of contaminants present at their single-metal EC10 concentrations, and (ii) an environmental mixture based on the ratio metal concentrations in a contaminated Antarctic marine bay. Observed toxicity, as chronic population growth rate inhibition, was compared to Independent Action (IA) and Concentration Addition (CA) predictions parameterised to use EC10 values. This allowed for the inclusion of metals with low toxicities. The biomarkers chlorophyll a fluorescence, cell size and complexity, and intracellular lipid concentrations were assessed to investigate possible mechanisms behind metal-mixture interactions. Both microalgae had similar responses to the equitoxic mixture: non-interactive by IA and antagonistic by CA. Toxicity from the environmental mixture was antagonistic by IA to P. antarctica; however, to C. armigera it was concentration-dependent with antagonism at low toxicities and synergism at high toxicities by both IA and CA. Differences in dissolved organic carbon production and detoxification mechanisms may be responsible for these responses and warrants further investigation. This study shows that mixture toxicity interactions can be ratio, species, and concentration dependent. The responses of the microalgae to different mixture ratios highlight the need to assess toxicity at environmentally realistic metal ratios. Parameterising IA and CA reference models to use EC10s allowed for the inclusion of metals at low effect concentrations, which may otherwise be ignored. Reference mixture models are generally suitable for predicting chronic toxicity of metals to these marine microalgae at environmentally realistic ratios and concentrations.
金属污染物在环境中很少单独存在，但环境质量指南是根据单一金属毒性数据得出的。很少有金属混合物研究调查了二元以上的混合物，而且许多研究的效应浓度对于淡水生物来说都是不现实的高浓度。本研究调查了五种金属（Cd、Cu、Ni、Pb 和 Zn）对南极海洋微藻 P. antarctica 和 C. armigera 的毒性。测试了两种混合物：（i）存在于其单一金属 EC10 浓度的污染物等毒性混合物，和（ii）基于受污染南极海洋湾中金属浓度比的环境混合物。观察到的毒性，如慢性种群增长率抑制，与独立作用（IA）和浓度加和（CA）预测进行了比较，这些预测是使用 EC10 值参数化的。这使得低毒性的金属也可以包括在内。评估了生物标志物叶绿素 a 荧光、细胞大小和复杂性以及细胞内脂质浓度，以研究金属混合物相互作用背后可能的机制。两种微藻对等毒性混合物的反应相似：IA 呈非交互作用，CA 呈拮抗作用。IA 对 P. antarctica 的环境混合物的毒性呈拮抗作用；然而，对 C. armigera，它是浓度依赖性的，IA 和 CA 均表现出低毒性拮抗作用和高毒性协同作用。溶解有机碳产生和解毒机制的差异可能是这些反应的原因，值得进一步研究。本研究表明，混合物毒性相互作用可能取决于比率、物种和浓度。微藻对不同混合物比率的反应突出表明需要在环境现实的金属比率下评估毒性。将 IA 和 CA 参考模型参数化以使用 EC10 值允许包括低效应浓度的金属，否则这些金属可能会被忽略。参考混合物模型通常适用于预测这些海洋微藻在环境现实的比率和浓度下金属的慢性毒性。
