【摘要】 表生环境中广泛存在纳米铁（氢）氧化物和磷酸盐矿物，这些物质相对磷（P）和稀土元素具有显著的固定作用。以含磷和稀土元素的水铁矿和磷灰石为磷源，采用透析方法（阻隔细胞与矿物），探究弱碱性和高CO₃^2-浓度条件下蓝藻（铜绿微囊藻，Microcystis aeruginosa）对纳米矿物结合态磷的利用及其对稀土元素的分馏作用。结果表明铜绿微囊藻可以较低的效率利用纳米矿物结合态磷，而溶解态和纳米颗粒结合态稀土元素均对铜绿微囊藻产生一定程度的毒害作用。稀土元素实验中，经过17 d的培养后，所有实验溶液均富重稀土；对于藻细胞及胞外多聚物，除高浓度溶解态稀土元素实验（富轻稀土）和水铁矿+透析实验（富重稀土）中出现稀土元素分馏外，其余实验中稀土元素均无分馏；丝状胞外多聚物富中稀土，尤其富含钐（Sm）、铕（Eu）和钆（Gd），而次生钙磷酸盐和铁（氢）氧化物则富集中—重稀土。研究认为，弱碱性条件下菌体及胞外多聚物对REE³⁺的选择性吸附导致溶液中总是富重稀土；溶液中稀土元素与阴离子(尤其是CO₃^2-)比值大时菌体和胞外多聚物中富轻稀土；稀土元素来源于矿物时，菌体及胞外多聚物中稀土元素分馏不明显；胞外多聚物选择性络合矿物中的稀土元素可能导致菌体及胞外多聚物中富重稀土；胞外多聚物及次生物相选择性富集中—重稀土可能具有潜在的环境指示意义。更多还原

【Abstract】 Nanosized iron（hydr）oxides and phosphate minerals are widely distributed in supergene environments and exhibit significant sequestration effects for phosphorus（P） and Rare Earth Element（REE）. Although previous studies have found that both forms of P can be utilized by microorganisms, the mechanism by which microbial activity constrains the geochemical behavior of mineral-bound REEs during P utilization has received little attention. This study investigated the utilization of Nano-mineral bound P by Microcystis aeruginosa and the associated REEs fractionation under weakly alkaline and high CO₃^2-conditions, using ferrihydrite（Fh） and apatite（Ap） loaded with P and REEs as P sources through dialysis methods（isolating cells from minerals）. The results demonstrated that M. aeruginosa utilized nano-mineral-bound P with low efficiency, while both dissolved and nano-mineral-bound REEs exhibited moderate toxicity to the cyanobacterium. In the REE experiments, all the solutions were enriched in Heavy REEs（HREEs） after 17 d of cultivation. For algal cells and Extracellular Polymeric Substances（EPS）, REE fractionation was observed only in experiments with high dissolved REE concentrations（enriched in LREEs and LREEs） and ferrihydrite + dialysis（enriched in HREEs）. Filamentous EPS preferentially accumulated middle REEs（MREEs, particularly Sm, Eu, and Gd）, whereas secondary calcium phosphates and iron（hydr）oxides sequestered MREEs-HREEs. It is considered that:（1） Selective adsorption of REE³⁺ under weak alkaline conditions by Cells and EPS（C&E） consistently enriches HREEs in solutions;（2） Cells and EPS enrichment in LREEs occurs when the REE/anion(especially CO₃^2-ratio in solution is elevated;（3） No REE fractionation in cells and EPS when REEs originate from mineral phases;（4） EPS-mediated selective REE complexation from minerals may drive HREE enrichment in cells and EPS;（5） Preferential accumulation of MREEs-HREEs in EPS and secondary solid phases may underlie the positive anomalies of these elements in eutrophic waters. Thus, anomalies in MREEs（e. g., Eu） may serve as effective proxies for assessing the degree of aquatic eutrophication.更多还原