稀土元素在长江口及邻近陆架表层沉积物中的分布及物源示踪研究

长江口邻近陆架表层沉积物中稀土元素含量及组成表明其主要来源为中国大陆陆源物质.轻重稀土元素比值对于区分长江和黄河流域来源物质具有一定的示踪意义,古黄河三角洲以较低的轻重稀土元素比值为特征,而长江来源物质以相对较高的轻重稀土比值为特征,沉积物粒度和Cl含量不是控制沉积区内稀土元素分馏的主要因素.通过聚类分析将研究区域划分为长江口近岸区和东海北部陆架区两个分区,黄海沿岸流、长江冲淡水以及台湾暖流是造成分区的关键水动力因素.分区内常量和微量元素以及同位素组成皆表现为不同程度差异,长江口近岸区化学组成和长江流域物质基本一致,东海北部陆架区与黄河流域物质比较接近.     

湟水河西宁段表层沉积物稀土元素地球化学特征及其物源分析

采样测定了湟水河西宁段表层沉积物28个样品的14种稀土元素地球化学含量,分析其含量、特征参数及配分模式,探讨其影响因素及物质来源。结果表明：湟水河西宁段表层沉积物中稀土元素总含量为89.75～217.58 mg·kg^-1,平均值为153.56 mg·kg^-1;28个样品的稀土元素含量变化较为一致,组成特征变化较小,轻稀土元素相对富集,重稀土元素相对亏损,Eu呈中等程度亏损,Ce呈无异常;沉积岩源岩及矿物组成对湟水河西宁段表层沉积物中稀土元素的组成起到控制作用,化学风化对稀土元素的组成无影响;湟水河西宁段表层沉积物的稀土元素特征参数、大陆上地壳和球粒陨石标准化配分模式与青海土壤、黄河沉积物接近,暗示了湟水河西宁段表层沉积物中稀土元素主要来源于湟水河河流侵蚀搬运物,同时其为黄河沉积物中稀土元素提供部分物源。     

北黄海中部晚第四纪沉积物来源的稀土元素示踪

对北黄海中部DLC70-2孔166个沉积物样品进行了稀土元素测定,结合粒度参数研究,以探讨北黄海中部DLC70-2孔稀土元素地球化学特征和物质来源。结果表明:DLC70-2孔岩心稀土元素分布特征分别反映了末次间冰期(暖期)晚期以来北黄海海面波动以及沉积物物源的变化。判别函数和稀土元素配分模式表明北黄海DLC70-2孔沉积物物源主要为黄河源和鸭绿江源。La/Yb判别图解揭示DLC70-2孔上部0~32.10 m和下部37.60~60.72 m沉积物以黄河源为主,中部32.10~37.60 m和底部60.72~70.45 m沉积物以鸭绿江源为主。研究表明晚更新世以来黄河对北黄海中部沉积起着重要作用,而鸭绿江物质对北黄海中部沉积作用也有明显影响。     

南大西洋中脊表层沉积物中稀土元素的含量及分布模式分析

以HNO3-H2O2-HF为消解体系,对南大西洋中脊16个站位表层沉积物进行消解,应用电感耦合等离子体质谱测定了沉积物中稀土元素(Rare earth elements,REE)的含量,并分析了稀土元素的分布特征。结果表明,微波消解-ICP-MS方法测定稀土元素,各元素的线性关系良好(r=0.9997~1.0000),检出限可达ng/L,精密度好、准确度高,相对标准偏差(RSD,n=3)不大于3.0%,相对误差在6.0%以内。16个站位沉积物样品中稀土总量(∑RE)变化范围为37.25~134.77μg/g,轻重稀土元素含量比值(LRE/HRE)的变化范围是0.61~1.70,平均值为1.27,沉积物中富集轻稀土略明显;从稀土配分模式看出,各个站位REE分布模式基本一致,轻重稀土元素之间有明显的分馏;不同来源沉积物中稀土元素分布模式类似,陆地和海洋沉积物稀土存在稍微差异;沉积物中δEu和δCe均出现负异常,说明了稀土元素主要是来自于海水。本研究分析了南大西洋中脊稀土元素的含量和分配规律,为深入研究大西洋中稀土元素的分布提供技术支撑和参考数据。     

三亚近岸海域表层沉积物稀土元素地球化学特征及物源分析

为充分了解三亚海岸带表层沉积物的物源状况,对三亚近岸海域331个站位表层沉积物的稀土元素进行了分析.结果表明:研究区表层沉积物稀土元素含量略低于南海大陆架和南海全区表层沉积物的平均水平,ΣREE含量分布特征与沉积物粒径有很好的相关性,符合"元素粒度控制律";δEu值也与沉积物粒度有关,与Mz(Φ)为较显著的负相关关系....     

厦门西海域表层沉积物中稀土元素分布特征

以厦门西海域表层沉积物为对象,研究了沉积物中稀土元素(REE)的分布特征.结果表明:厦门西海域沉积物中REE含量为125.71～206.02 μg·g-1,西部港湾区的8号和九龙江口的2号采样点REE含量较高,且轻稀土占绝对优势.REE含量随沉积物粒级呈有规律的变化,REE含量最高的是＜63μm的粒级,最低的是250 μm的粒级;沉积物经球粒陨石标准化后,各粒级REE总体配分曲线相近,均表现为明显的Eu亏损和Ce亏损,且＜63μm粒级亏损尤为严重.Eu与Ce异常平均值均小于黄河流域和长江流域沉积物;＜63μm粒级的沉积物中轻重稀土分馏程度最高,但在其他三种粒级沉积物中由粗到细分馏程度逐渐降低.分馏现象表明细粒级沉积物轻重分馏较粗粒级明显.与当地土壤稀土元素背景值比较,沉积物主要来自厦门西海域本地的土壤.     

长江下游下蜀黄土的稀土元素物源判别

通过对长江下游镇江、福家湾、新港、芜湖、福路镇等地区下蜀黄土中稀土元素的研究,结合长江古漫滩堆积物及北方黄土沉积物,对下蜀黄土进行了物源判别,得出：下蜀黄土与长江河漫滩之间的各稀土元素的 DF 值绝大部分小于0．2,表现出在各个稀土元素上与河漫滩的接近程度较大,而与北方黄土接近程度较小;由物源指数 PI 计算得出,新港、福路镇、镇江下蜀黄土 PI 值均在0．2附近,表现出下蜀黄土与河漫滩在稀土元素总体上的相似程度极高,物源判别为长江河漫滩;福家湾下蜀黄土物源判别为北方黄土,北方黄土对其有一定影响。总体上,长江下游下蜀黄土受到北方黄土与河漫滩的影响,其中以长江河漫滩影响为主。     

植酸与稀土元素的固态配合物的研究

植酸（PllytiC。Cid）又称肌醇六磷酸酯（myo－iflOSitdhX。hSPhOSPh。ie）（简写为H12lHP］常以钙、镁复盐（菲汀Phntin）形式存在于植物中,尤其在谷类和植物的种子中含量较高［'j．植酸具有惊人的骛合能力,除碱金属外几乎能与所有金属离子生成沉淀,一些高价金属离于甚至在强酸性介质中也可定量沉淀［如Ti、Zr、Hf、Th、Ce（IV）和In、Sc等〕,这些性质已初用于Th'"的定量测定L'和SC'"的分离提取「",Gd'"与植酸的配合物被用作核磁共振成倍（MRI）的对比剂［'j．然而,对有关配合物的固态组成及性质研究尚无文献报道．本文…     

湖州表层土壤稀土元素含量及分布特征

为了研究湖州表层土壤样品中稀土元素的分布特征,利用ICP-MS测定了土壤中稀土元素的含量。结果表明湖州表层土壤中稀土元素含量的大小顺序为：Ce＞La＞Nd＞Pr＞Sm＞Gd＞Dy＞Yb＞Er＞Eu＞Ho＞Tb＞Tm＞Lu,遵循Oddo-Harkins法则。湖州表层土壤中稀土元素的分量均值和总量均值皆高于全国水平,稀土元素存在显著的分馏现象,轻稀土元素明显富集。表层土壤中Ce和Eu都有部分亏损。     

Rare Earth Elements and Bioavailability in Northern and Southern Central Red Sea Mangroves,Saudi Arabia

Different hypotheses have been tested about the fractionation and bioavailability of rare earth elements (REE) in mangrove ecosystems. Rare earth elements and bioavailability in the mangrove ecosystem have been of significant concern and are recognized globally as emerging pollutants. Bioavailability and fractionation of rare earth elements were assessed in Jazan and AlWajah mangrove ecosystems. Comparisons between rare earth elements, multi-elemental ratios, geo-accumulation index (Igeo), and bio-concentration factor (BCF) for the two mangroves and the influence of sediment grain size types on concentrations of rare earth elements were carried out. A substantial difference in mean concentrations (mg/kg) of REE (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) was established, except for mean concentrations of Eu, Gd, Tb, Tm, and Lu. In addition, concentrations of REEs were higher in the Jazan mangrove ecosystem. However, REE composition in the two mangroves was dominated by the lighter REE (LREE and MREE), and formed the major contribution to the total sum of REE at 10.2–78.4%, which was greater than the HREE contribution of 11.3–12.9%. The Post Archean Australian Shale (PAAS) normalized values revealed that lighter REE (LREE and MREE) were steadily enriched above heavy REE. More so, low and negative values of R_(H/M) were recorded in the Al Wajah mangrove, indicating higher HREE depletion there. The values of BCF for REEs were less than 1 for all the REEs determined; the recorded BCF for Lu (0.33) and Tm (0.32) were the highest, while the lowest BCF recorded was for Nd (0.09). There is a need for periodic monitoring of REE concentrations in the mangroves to keep track of the sources of this metal contamination and develop conservation and control strategies for these important ecosystems.     

Studies in the Field of Rare Earth Elements

The article describes developed and implemented technologies in the field of rare earth elements. Besides, new promising technologies for the realization of the work, carried out at the Department of Chemistry MEPhI in recent years, are represented.     

稀土元素分离检测技术新进展

对2003年以来稀土元素分离检测技术的新进展进行了评述，重点集中于各种新型分离技术、新型检测技术及其在稀土元素分析中的应用。对于离子液体、纳米材料、离子印迹聚合物等新型材料以及浊点萃取、膜萃取、毛细管电泳等新型技术在稀士元素分离中的应用进行了详细讨论，并对中子活化分析、等离子体原子发射光谱和等离子体质谱在稀土元素检测中的应用进行了综述，重点讨论了等离子体质谱技术的应用。在回顾稀土元素分离检测技术进展的同时，对其在未来几年的发展趋势进行了评述。     

Biohydrometallurgy for Rare Earth Elements Recovery from Industrial Wastes

Biohydrometallurgy recovers metals through microbially mediated processes and has been traditionally applied for the extraction of base metals from low-grade sulfidic ores. New investigations explore its potential for other types of critical resources, such as rare earth elements. In recent times, the interest in rare earth elements (REEs) is growing due to of their applications in novel technologies and green economy. The use of biohydrometallurgy for extracting resources from waste streams is also gaining attention to support innovative mining and promote a circular economy. The increase in wastes containing REEs turns them into a valuable alternative source. Most REE ores and industrial residues do not contain sulfides, and bioleaching processes use autotrophic or heterotrophic microorganisms to generate acids that dissolve the metals. This review gathers information towards the recycling of REE-bearing wastes (fluorescent lamp powder, spent cracking catalysts, e-wastes, etc.) using a more sustainable and environmentally friendly technology that reduces the impact on the environment.     

微量稀土元素的药效及保健作用

根据国内外微量稀土元素在医药方面应用的研究,介绍了稀土元素的一系列特殊的药效及保健作用。稀土元素可广泛用于治疗烧伤,炎症,皮肤病,血栓病等。     

Thermal Stability of 4-Chloro-3-Nitro- and 5-Chloro-2-Nitrobenzoates of Rare Earth Elements

The physico-chemical properties and thermal stabilities in air of rare earth element 4-chloro-3-nitrobenzoates and 5-chloro-2-nitrobenzoates were compared and the influence of the positions of the Cl and NO₂ substituents on their thermal stabilities was investigated. The complexes of both series are crystalline, hydrated or anhydrous salts with colours typical of Ln³⁺. The carboxylate group in these complexes is a bidentate, chelating ligand. The NO₂ group in the chloronitro complexes does not undergo isomerization. The thermal stabilities of the 4-chloro-3-nitrobenzoates of Y and the lanthanides were studied in the temperature range 273-1173 K, but those of the 5-chloro-2-nitrobenzoates of these elements were studied only at 273-523 K, because they decompose explosively above 523 K. The positions of the Cl and NO₂ substituents on the benzene ring influence the thermal properties of the complexes and their decomposition mechanisms. The different thermal stabilities of the complexes are connected with various inductive and mesomeric effects of the Cl and NO₂ substituents on the electron density in the benzene ring. This revised version was published online in July 2006 with corrections to the Cover Date.     

Spectrochemical and Thermal Behaviour of the 5-chloro-2-nitrobenzoates of Rare Earth Elements

The conditions of the formation of yttrium and lanthanide 5-chloro-2-nitrobenzoates were studied and their quantitative composition and solubilities in water at 298 K were determined. They are anhydrous or hydrated complexes and their solubilities are of the order of 10-3 mol dm-3. The IR and X-ray spectra for the complexes were recorded. All complexes are crystalline compounds. Their thermal decomposition was studied. It was found that on heating above 523 K the complexes decompose explosively. Therefore their thermal decomposition was carried out in the temperature range 273-523 K. Hydrated complexes lose crystallization water molecules in one step. From the results it appeared that during dehydration process no transformation of nitro group to nitrito took place. Some of physico-chemical properties of rare earth element 5-chloro-2-nitrobenzoates were compared with 2-nitro- and 3-chlorobenzoates of those elements. This revised version was published online in July 2006 with corrections to the Cover Date.