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 （REEs）具有显著固定作用。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、高CO23-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，而溶解态及含稀土元素纳米颗粒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，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是Sm、Eu、Gd，次生钙磷酸盐及铁（氢）氧化物富中 稀土—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CO^2-₃）比值大时菌体及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稀土—重 稀土可能具有潜在的环境指示意义。

Abstract： In supergene environments, nanosized iron (hydr)oxides and phosphate minerals are widely distributed and exhibit significant sequestration effects on phosphorus (P) and rare earth elements (REEs). Although previous studies have found that both forms of P can be utilized by microorganisms, how microbial activities constrain the geochemical behavior of mineral-bound REEs during P utilization has received little attention thus far. This study investigated the utilization of Nano-mineral bound P by Microcystis aeruginosa and the associated REEs fractionation under weakly alkaline and high CO23- conditions, using ferrihydrite (Fh) and apatite (Ap) loaded with P and REEs as P sources through dialysis methods (isolating cells from minerals). Results demonstrated that M. aeruginosa utilized Nano-mineral bound P at low efficiency, while both dissolved and Nano-mineral bound REEs exhibited moderate toxicity to the cyanobacterium. In REE experiments, all solutions were enriched in heavy REEs (HREEs) after 17 day cultivation. For algal cells and extracellular polymeric substances (EPS), REE fractionation was observed only in experiment with highly dissolved REE concentration (enriched in light REEs, LREEs) and experiment of ferrihydrite + dialysis (enriched in HREEs). Filamentous EPS preferentially accumulated middle REEs (MREEs, particularly Sm, Eu, and Gd), while secondary calcium phosphates and iron (hydr)oxides sequestered MREEs −HREEs. It is considered that: ①The selective adsorption of REE³ ⁺ under weak alkaline conditions by cells and EPS (C&E) consistently enriches HREEs in solutions; ②Cells and EPS enrichment in LREEs occurs when the REE/anion (especially CO₂^3-) ratio in solution is elevated; ③No REE fractionation in cells and EPS when REEs originate from mineral phases; ④ EPSmediated selective REE complexation from minerals may drive HREE enrichment in cells and EPS; ⑤ The preferential accumulation of MREEs−HREEs in EPS and secondary solid phases may be the underlying cause of positive anomalies of these elements in eutrophic waters. Thus, anomalies of MREEs (e. g., Eu) may serve as effective proxies for assessing the degree of aquatic eutrophication.