Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, Tallinn 12618, Estonia; Institute of Ecology and Earth Sciences, University of Tartu, Lai 40, 51005 Tartu, Estonia.
Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, Tallinn 12618, Estonia.
Sci Total Environ. 2017 Sep 1;593-594:478-486. doi: 10.1016/j.scitotenv.2017.03.184. Epub 2017 Mar 27.
Use of rare earth elements (REEs) has increased rapidly in recent decades due to technological advances. It has been accompanied by recurring rare earth element anomalies in water bodies. In this work we (i) studied the effects of eight novel doped and one non-doped rare earth oxide (REO) particles (aimed to be used in solid oxide fuel cells and gas separation membranes) on algae, (ii) quantified the individual adverse effects of the elements that constitute the (doped) REO particles and (iii) attempted to find a discernible pattern to relate REO particle physicochemical characteristics to algal growth inhibitory properties. Green algae Raphidocelis subcapitata (formerly Pseudokirchneriella subcapitata) were used as a test species in two different formats: a standard OECD201 algal growth inhibition assay and the algal viability assay (a 'spot test') that avoids nutrient removal effects. In the 24h 'spot' test that demonstrated direct toxicity, algae were not viable at REE concentrations above 1mgmetal/L. 72-hour algal growth inhibition EC values for four REE salts (Ce, Gd, La, Pr) were between 1.2 and 1.4mg/L, whereas the EC for REO particles ranged from 1 to 98mg/L. The growth inhibition of REEs was presumably the result of nutrient sequestration from the algal growth medium. The adverse effects of REO particles were at least in part due to the entrapment of algae within particle agglomerates. Adverse effects due to the dissolution of constituent elements from (doped) REO particles and the size or specific surface area of particles were excluded, except for LaNiO. However, the structure of the particles and/or the varying effects of oxide composition might have played a role in the observed effects. As the production rates of these REO particles are negligible compared to other forms of REEs, there is presumably no acute risk for aquatic unicellular algae.
由于技术进步，近几十年来稀土元素（REEs）的使用迅速增加。与此同时，水体中也经常出现稀土元素异常。在这项工作中，我们（i）研究了八种新型掺杂和一种未掺杂的稀土氧化物（REO）颗粒（旨在用于固体氧化物燃料电池和气体分离膜）对藻类的影响，（ii）量化了构成（掺杂）REO 颗粒的元素的个别不利影响，（iii）试图找到一种明显的模式，将 REO 颗粒的物理化学特性与藻类生长抑制特性联系起来。绿藻莱茵衣藻（以前称为假鱼腥藻）被用作两种不同形式的测试物种：一种是经合组织 201 年藻类生长抑制测定法和藻类活力测定法（“点测试”），该测试法避免了营养物质去除的影响。在直接毒性的 24 小时“点”测试中，当 REE 浓度高于 1mgmetal/L 时，藻类就无法生存。四种 REE 盐（Ce、Gd、La、Pr）的 72 小时藻类生长抑制 EC 值在 1.2 到 1.4mg/L 之间，而 REO 颗粒的 EC 值在 1 到 98mg/L 之间。REE 的生长抑制作用可能是由于藻类生长培养基中的营养物质被螯合。REO 颗粒的不良影响至少部分是由于藻类被困在颗粒团聚体中。（掺杂）REO 颗粒中组成元素的溶解、颗粒的粒径或比表面积等造成的不利影响除外，LaNiO 除外。然而，颗粒的结构和/或氧化物组成的不同影响可能在观察到的影响中发挥了作用。由于这些 REO 颗粒的生产速率与其他形式的 REEs 相比微不足道，因此水生单细胞藻类可能没有急性风险。
