长江与黄河沉积物REE地球化学及示踪作用

长江与黄河沉积物的稀土元素（ＲＥＥ）组成特征不同。长江沉积物ＲＥＥ含量较高,元素含量变化也大于黄河样品;球粒陨石标准化模式表明长江沉积物的（Ｌａ／Ｌｕ）Ｎ、（Ｌａ／Ｙｂ）Ｎ、（Ｇｄ／Ｙｂ）Ｎ的值也相应地比黄河沉积物中的高１０％左右,分布曲线均呈明显的石倾状,轻重稀土分馏明显,相对富集ＬＲＥＥ。且长江样品比黄河样品更富集ＬＲＥＥ,但Ｅｕ亏损不及黄河样品;两者的北美页岩标准化曲线均呈平坦稍右倾状,具有     

内蒙古大石寨地区稀土元素的区域分布特征

总结了内蒙古大石寨地区1∶25万区域地球化学调查获得的1点/4km2的水系沉积物组合样品中的La、Ce、Pr、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu、Y等15种稀土元素的区域地球化学分布特征。稀土元素分布与研究区中部的黑云母花岗岩密切相关,轻稀土主要分布在该岩体外围的二叠系地层中,重稀土主要分布在该岩体上方。该岩体上方和外围地层的稀土元素分布、稀土元素总量、轻重稀土比及δCe、δEu、(La/Sm)N、(La/Tb)N、(La/Lu)N、(Ce/Yb)N、(Gd/Lu)N等稀土元素分馏特征的差异明显。利用区域地球化学调查水系沉积物样品中的稀土元素含量,可获得研究区可靠的稀土元素区域地球化学分布特征,也可反映研究区地质特点,并为区域地球化学异常解译提供参考资料。     

Post-depositional redistribution processes and their effects on middle rare earth element precipitation and the cerium anomaly in sediments in the South Korea Plateau,East Sea

We sampled two box-core sediments from the slope of the eastern South Korea Plateau (SKP) in the East Sea (Sea of Japan) at water depths of 1400 and 1700 m. Two chemical fractions of extractable (hydroxylamine/acetic acid) and residual rare earth elements (REEs) together with Al, Ca, Fe, Mg, Mn, P, S, As, Mo, and U were analyzed to assess the post-depositional redistribution of REEs. Extractable Fe and Mn are noticeably abundant in the oxic topmost sediment layer (<3 cm). However, some trace elements (e.g., S, As, Mo, U) are more abundant at depth, where redox conditions are different. Analysis of upper continental crust (UCC)-normalized (La/Gd)_UCC, (La/Yb)_UCC, and (Ce/Ce^*)_UCC revealed that the extractable REE is characterized by middle REE (MREE) enrichment and a positive cerium (Ce) anomaly, different from the case of the residual fraction which shows slight enrichment in light REEs (LREEs) with no Ce anomaly. The extractable MREEs seem to have been incorporated into high-Mg calcite during reductive dissolution of Fe oxyhydroxides. In the top sediment layer, the positive Ce anomaly is attributed to Ce oxide, which can be mobilized in deeper oxygen-poor environments and redistributed in the sediment column. In addition, differential concentrations of Ce and other LREEs in pore water appear to result in variable (Ce/Ce^*)_UCC ratios in the extractable fraction at depth.     

Geochemical characteristics and provenance implication of rare earth elements in surface sediments from bays along Guangdong Coast, Southeast China

A systematic study of the granulometric properties and the occurrence and distribution of rare earth elements (REE) within surface sediments from ten bays situated along the coast of Southeast China has facilitated a more rigorous understanding of constraints on sediment provenance in the area. The results show that REE concentrations are similar within a single bay, but vary considerably (133.58–251.77 mg/kg) among the bays. The chondrite-normalized distribution patterns show the typical enrichment of light REEs (LREEs: La–Eu) relative to heavy REEs (HREEs: Gd–Lu), and an apparent depletion of Eu, which is diagnostic of a terrigenous sediment source. Obvious enrichments of the middle REEs (MREEs: Sm–Ho) in the PAAS-normalized (Post-Archean Australian Shale) distribution patterns of these bay sediments are similar to results reported from large rivers in China. Comparing the REE composition of the bay sediments with those of adjoining fluvial sediments and with the bedrock of the surrounding drainage basins, the latter are indicated as the dominant sediment source. The uniform REE distribution patterns, and MREE enrichments, prove that the sediments are derived from the material transported by the streams and rivers that discharge into the bays.     

Evolution in the provenance of a tectonically controlled Plio–Pleistocene alluvial system between the Variscan Iberian Massif and the Atlantic margin, Portugal

Geochemical and mineralogical data from a Pliocene to Pleistocene alluvial sequence are integrated to access the factors that control rare earth elements (REE) geochemistry and the evolution and spatial differences in provenance. The studied alluvial system is situated in a tectonic active setting at the contact between the Variscan Massif, with several Paleozoic and Precambrian units that support a coastal range, and the Atlantic margin. REE and HREE abundances are generally higher in swamp-lake than in floodplain sediments. The majority of the REE in floodplain sediments is hosted by Y and Th-bearing minerals and illite; in swamp-lake sediments is also probable an association with organic matter. The high Gd/Yb, Eu/Eu* and kaolinite content in older sediments suggest that during the earlier phases provenance was mainly from the hinterland (weathered granitic rocks and its sediment cover). The subsequent illite (Mg-rich) clay assemblages and REE patterns indicate mainly lateral input from the eastern basin edge (Palaeozoic and Precambrian metapelitic rocks). These sediments tend to have lower Gd/Yb and La/Sm than their source rocks. The analysis of the chemical index of alteration (CIA) indicates that although a north-directed fluvial axis existed at that time the “mature” basin edge units found to the south (Silurian) had a limited role in supplying sediments. This shift in provenance is attributed to the uplift of the coastal range. Afterwards, the contribution of recycled Cretaceous and Cenozoic sedimentary units increased progressively. This is demonstrated by the increase is SiO₂/TiO₂, CIA and kaolinite/illite when the climatic conditions are expected to have become less chemically aggressive.     

Do Archean chemical sediments record ancient seawater rare earth element patterns?

Rare earth elements (REE) concentrations of Archean and Proterozoic chemical sediments are commonly used as proxies to study secular trends in the geochemistry of Precambrian seawater. In addition, similarities in the REE signatures of Archean chemical sediments and modern seawater have led researchers to argue that some Archean rocks originated as biochemical precipitates (i.e., microbial carbonates) in shallow marine (e.g., peritidal) environments. However, terrestrial waters, including river water and groundwater, also commonly exhibit REE fractionation patterns that resemble modern seawater. Here, we present the seawater-like REE data for groundwaters from central México as additional evidence that these patterns are not unique to the marine environment. The shale-normalized REE patterns of the groundwaters are compared to those of modern seawater (open ocean and nearshore), Holocene reefal microbial carbonates and corals, and Archean chemical sediments using statistical means (i.e., ANOVA and Wilcoxon analyses) in order to quantify the similarities and/or differences in the REE patterns. Shale-normalized (SN) Ce anomalies and measures of REE fractionation [i.e., (La/Yb)_SN, (Pr/Yb)_SN, (Nd/Yb)_SN, and (Gd/Yb)_SN] of the central México groundwater samples are statistically indistinguishable from those of modern seawater. Moreover, except for differences in the Ce anomalies, which are lacking in Archean chemical sediments, the REE patterns of the central México groundwaters are also statistically similar to REE patterns of Archean chemical sediments, especially those of the 3.45 Ga Strelley Pool Chert. Consequently, we suggest that without additional information, it may be premature to unequivocally conclude that Archean chemical sediments record REE signatures of an Archean ocean.     

中全新世以来西南极阿蒙森海沉积物来源和古气候意义

对西南极阿蒙森海A11-02孔沉积物进行粒度和地球化学元素分析,示踪了阿蒙森海沉积物来源,重建了中全新世以来的古气候演化历史。通过对稀土元素北美页岩平均标准化配分曲线以及(La/Yb)_N、(Gd/Lu)_N、(La/Sm)_N等参数的分析和对比,认为A11-02孔沉积物主要来源于玛丽伯德地,而别林斯高晋海也有一定贡献。通过将化学蚀变指数、Na/K、<22.1 μm粒级组分含量以及>63 μm粒级组分含量等相关替代指标与其他古气候记录对比,识别出中全新世以来在阿蒙森海存在4个明显的寒冷阶段(P1-P4)。在时间和空间上,南极地区千年尺度的气候变化具有一致性,主要受日照强度变化和大气环流变化控制。     

湛江湾海域表层沉积物稀土元素特征及其物源指示意义

通过对湛江湾近海海域表层沉积物样品粒度和稀土元素(RE E)测试分析,系统地研究海域沉积物稀土元素地球化学特征并探讨其物质来源.结果表明,研究区沉积物的稀土元素含量变化较大,平均值为163.23μg/g,湾外的REE含量(168.61μg/g)高于湾内的REE含量(142.17μg/g);不同类型沉积物的稀土元素含量存...     

Rare earth elements in the sedimentary cycle: A summary

The relative and absolute concentrations of rare earth elements (REE) in authigenic and biogenic phases of deep-sea sediments are quite different. Competition between these phases for REE has resulted in fractionation from the parent material, the latter consisting predominantly of terrigenous material, but with a contribution from marine volcanism. The strongest feature of this fractionation is a depletion of Ce, relative to La, in CaCO₃, opalline silica, phillipsite, phosphorite, barite, and montmorillonitic clays; and a Ce enrichment in Fe/Mn nodules. The distribution of REE in different masses of seawater strongly reflects their fractionation in sediments. Whereas the relative concentration of REE in rivers resembles that of shale, their removal from seawater by authigenic and biogenic phases results in: (1) a decrease of their total concentration; (2) a depletion of Ce; and (3) an enrichment of heavy REE relative to light REE. The order of fractionation for water masses in the Atlantic Ocean is:Antarctic intermediate water > North Atlantic deep water > Antarctic bottom water> shelf water > river water ～ shale.The shale-normalized pattern for the sum of REE in the authigenic and biogenic phases of pelagic sediment and in seawater resembles that of an admixture of shale and basalt corresponding presumably to the realtive inputs from continents and marine volcanism respectively. The estimated rate of accumulation of each REE in the sediment, however, is approximately 12 times the estimated rate of input of REE from these two sources.     

鄱阳湖流域赣江北支水体和沉积物中稀土元素的含量和分异特征

稀土的开发和广泛应用使得人们倍加关注其在环境中的分布及其环境地球化学行为。赣江作为鄱阳湖流域五大入湖河之一,发源于稀土资源富集的赣南地区,而其下游水体及周边地下水中稀土元素的含量和分异特征目前尚不完全清楚。以赣江北支水体及沉积物为研究对象,开展了稀土元素地球化学研究。结果表明,赣江北支水体中稀土元素总量在地表水中为230~1 146 ng/L(均值458.85 ng/L),地下水中为284~1 498 ng/L(均值634.94 ng/L),沉积物中稀土元素总量为177.9~270.7 mg/kg(均值226.99 mg/kg)。PHREEQC模拟计算表明,水体中的稀土元素主要以碳酸根络合物(REEC0₃⁺)的形式存在。地表水和地下水总体上均表现为重稀土元素相较于轻、中稀土元素富集,沉积物未表现出明显的富集特性;水体具有Ce、Eu负异常特点,而沉积物表现为Ce正异常和Eu负异常,指示氧化还原环境和水岩相互作用对稀土元素在水-沉积物系统中迁移转化的影响。地下水中稀土元素的含量沿流向具有上升趋势,而水体中重稀土元素的富集程度不断减弱,同时碳酸根络合物(REEC0₃⁺)的占比不断降低,反映水体中稀土元素的含量受到pH、胶体吸附、络合作用以及地下水-地表水相互作用的影响。水体中重稀土元素的富集受到碳酸根络合反应的影响,Ce、Eu负异常与Ce氧化沉淀和母岩特性相关。Gd异常值表明,研究区中下游水体中的Gd元素受到人为输入的影响。     

淮南采煤沉陷区表层沉积物稀土元素地球化学特征

稀土元素由于其独特的化学特征被广泛应用于环境地球化学分析过程研究。以淮南采煤沉陷区表层沉积物中稀土元素(REEs)为研究对象,采集研究区潘一、顾桥、谢桥沉陷区的表层沉积物样品共12个,采用ICP-MS对样品的稀土元素含量进行测试分析,探讨了表层沉积物中稀土元素的含量分布特征、控制因素及其物质来源。结果表明:研究区表层沉积物中稀土元素含量为54.63~130.45 μg/g,平均102.60 μg/g;LREE/HREE比值为11.89~20.55,平均14.29,轻稀土呈现明显富集现象;相关性分析结果显示,REEs趋向于黏土组分中富集;研究区养殖和捕捞活动导致表层沉积物中稀土元素含量的降低;球粒陨石标准化结果表明,研究区稀土元素呈现不同程度的La和Gd正异常,其中,Gd正异常主要是受到燃煤的影响,而La正异常主要与燃煤和化肥有关。结合Pearson相关性、球粒陨石标准化和(La/Yb)_N-(La/Sm)_N-(Gd/Yb)_N三元图判别,认为研究区水体表层沉积物中稀土元素与人类活动(燃煤和化肥)有关,研究认识为污染物的源头控制和煤矿区环境的生态治理提供参考依据。      

Geochemical and mineralogical characteristics of recent clastic sediments from lower Godavari river: Implications of source rock weathering

The major, trace and rare earth elements geochemistry and clay mineral compositions in the river bed sediments from lower reaches of Godavari river suggest that they are derived from weathering of felsic rocks. Trace and rare earth elemental compositions indicate evidence of sedimentary sorting during transportation and deposition. Lower concentrations of transition elements, such as V, Ni and Cr imply enrichment of felsic minerals in these bed sediments. The REE pattern in lower Godavari sediments is influenced by the degree of source rock weathering. The light rare earth elements (LREE) content are indicating greater fractionation compared to the heavy rare earth elements (HREE). A striking relationship is observed between TiO₂ and gZREE content suggesting a strong control by LREE-enriched titaniferous minerals on REE chemistry. Shale-normalized REE pattern demonstrate a positive Eu anomaly, suggesting weathering of feldspar and their secondary products, which are enriched in Eu. Chondrite-normalised REE pattern is characteristic of felsic volcanic, granites and gnessic source rocks. Trace elemental compositions in sediments located near urban areas suggest influence of anthropogenic activity. Chemical Index of Alteration (CIA) is high (avg. 65.76), suggesting a moderate chemical weathering environment. X-ray diffraction analysis of clay fraction shows predominance of clay minerals that are formed because of the chemical weathering of felsic rocks.     

Lower Palar River Sediments,Southern Peninsular,India: Geochemistry,Source-Area Weathering,Provenance and Tectonic Setting

This present study describes the geochemistry of fluvial sediments of the Palar river (lower reaches), Southern Peninsular India, with an aim to evaluate their provenance, weathering and tectonic setting. The bulk sediment chemistry is influenced by grain size. The river sediments are enriched with SiO₂ and depleted in Al₂O₃, K₂O, CaO, Na₂O, MgO, P₂O₅, MnO, Fe₂O₃ as compared with UCC values. Geochemical classification indicate that the sediments are mainly arkose, wacke and shale in composition. Discriminant diagrams together with immobile element ratio plots reveal that, the Palar river sediments are mostly derived from rocks formed in an active continental margin. Additionally, the rare earth element ratios as well as chondrite-normalized REE patterns with flat HREE, LREE enrichment, and negative Eu anomalies indicate felsic rock sources. The chemical indices of alteration suggest that Palar river sediments are chemically immature and have experienced low chemical weathering effects. This is further supported by the Th/U Rb/Sr ratio and A-CN-K ternary diagram, with most of the sample data points falling close to the plagioclase-smectite line. The bivariate plot of Th/Sc versus Zr/Sc suggest a moderate recycled origin of the sediments.     

北京平原沉积物稀土元素地球化学特征及物源意义

文中总结了北京平原永定河、潮白河流域钻孔沉积物中稀土元素分布特征,两流域沉积物稀土元素总量∑REE、轻重稀土比(LREE/HREE)及轻(La/Sm)N、重(Gd/Yb)N稀土分馏特征差异较为显著。粒度对沉积物稀土分布(总量、轻重稀土比及分馏特征)有一定影响;各流域沉积物均表现为轻稀土相对富集、弱Eu负异常的球粒陨石标准化曲线。细颗粒沉积物稀土分馏特征(La/Yb)N有较好的物源示踪意义。根据沉积物(La/Yb)N值对永定河、潮白河交互沉积区不同深度沉积物进行了物源示踪,不同深度上沉积物来源不同。此外,同一流域上、中、下游沉积物稀土分馏特征不同。常量元素Al2O3/Fe2O3与稀土元素(La/Yb)N划分结果相符,但精度低于稀土元素物源分析。     

Temporal changes in trace elements in brown soil and soybean after long-term fertilization

In agricultural production, specific elements in soil and plants are very important for the soil quality and plant productivity. Trace elements and rare earth elements enter in agri-environment by the application of fertilizers and, through anthropogenic activities, pose important health impacts even at low concentration due to non-biodegradable nature with long half-life. The micro nutrients are essential for human body in a quantity most of less than 100 mg/day. The nutritional element uptake by plants is regulated by availability of the required elements and element accumulation ability of the plants. Therefore, this study was aimed to investigate the accumulation of trace and rare earth elements after long-term application of different fertilizers in soil and soybean uptake. The inorganic fertilizers (NKP) and pig manure were applied to maize-maize-soybean rotation in Alfisols (brown) soil since 1979. Atomic emission spectrometry along with inductively coupled plasma technique was applied to determine trace and rare earth elements. The accumulation pattern of trace elements (TEs) observed in soil was Ni > Co > Se > Mo and rare earth elements (REEs) was found as La > Nd > Tb > Y > Pr > Gd > Er > Yb > Lu. In soybean stem, the TE and REE concentrations were Se > Ni > Co > Mo and Pr > Gd > Er > Yb > Tb > Nd > Lu > La > Y, respectively. Elemental concentrations in the seed samples were Ni > Se > Mo > Co and Pr > Gd > Er > Yb > Tb > Nd > Lu > Y > La. The seed of soybean accumulated Co, Mo, Ni, Gd, Pr, Er, Lu, and Tb more than the stem. Higher concentrations of Se, Nd, Y, and Yb were found in soil. These elements were higher in soybean stem followed by the seed. However, these elements are within safe toxic level and light pollution level.     

Major and trace element geochemistry of superficial sediments and suspended particulate matter of shallow saline lakes in Eastern Austria

General geochemical parameters of water, superficial sediments, and suspended particulate matter (SPM) were determined from small shallow saline lakes (soda ponds) as well as from lake Neusiedlersee in eastern Austria. Additionally, instrumental neutron activation analysis (INAA) was used to determine the distribution of major, rare earth and other trace elements in superficial sediments and SPM. Chemical results show remarkable differences in salinity and ionic strength between the investigated ponds. Anthropogenic effects, such as drawdown of ground water level and a loss of lake water due to drainage, are clearly reflected in obtained chemical and geological data. Due to a strong dependence of the complexation and scavenging behavior of the rare earth elements (REE) on ionic strength, a significant difference between REE concentrations in soda ponds with different anthropogenic impact was found. The content and composition of authigenic evaporitic minerals in superficial sediments and SPM clearly differ with a fluctuating water level and salt concentration. Furthermore, we determined the distribution of major and trace elements in superficial sediments of a nearby fluvial system. Our results show a clear correlation between REE superficial sediment concentrations in anthropogenically degraded soda ponds and fluvial system. Therefore, we assume that REE concentrations of sediments and SPM are suitable for the study of geochemical changes of inland saline lakes due to anthropogenic impacts on water balance.     

REE geochemistry of fine-grained sediments from major rivers around the Yellow Sea

To investigate the distribution pattern and controlling factors of rare earth elements (REEs) in riverine sediments, river mouth sediments were collected at five geographically different rivers around the Yellow Sea. Two- (1 M HCl leached and residual fractions) and five-step sequential extraction schemes (the SEDEX method) were applied to size-separated sediments < 20 µm. For the total REE composition, patterns normalized relative to the upper continental crust (UCC) showed light REE (LREE) and middle (MREE) enrichments in the Korean river sediments and MREE enrichment in the Chinese river sediments. LREE and MREE enrichments in 1 M HCl leached fractions played a major role in the distribution patterns of the total compositions in all the river sediments. About half of LREE enrichment in Korean river sediments was explained by the residual fraction. Comparison of the REE composition with major elements (Al, Fe, Ca, P) in each fraction of the SEDEX scheme revealed that MREE enrichment could be explained by reactive iron minerals, including goethite and hematite, although REE/Fe ratios showed different trends among the rivers due to different major REE-host iron minerals. After extracting reactive irons, authigenic phosphate, and carbonate, the sequential 1 M HCl fraction indicated that LREE enrichment in Korean river sediments may have originated from clay minerals, such as chlorite. These observations suggest that LREE enrichment may be a good tracer, while MREE enrichment should be used cautiously considering diagenetic modification, when using the REE composition to identify the sources of terrestrial materials.     

长江口晚新生代沉积物的物源研究: REE和Nd同位素制约*

长江三角洲地区第四纪以来堆积了200多米厚的碎屑沉积物,主要由河湖相和滨浅海相组成,构成了多个沉积旋回。选择长江口地区一个320m深的PD钻孔,运用多通道等离子体质谱MC ICP-MS方法,开展沉积物中的REE和Nd同位素组成分析,研究了上新世以来三角洲地区沉积物物源的变化。沉积物中REE和Nd同位素组成具有明显的变化规律,Ce呈弱的负异常,介于0.83~0.99之间,而Eu呈现中等亏损,在0.53~0.73之间变化。岩芯中上新统沉积物中Ce异常变化大,而Eu亏损相对第四系沉积物更显著。¹⁴³ Nd/¹⁴⁴ Nd比值在钻孔中变化较小,介于0.511975~0.5122367之间,平均值为0.512062。相关分析揭示粒度和化学风化对Nd同位素组成影响小。REE和Nd同位素判别图解揭示河口地区上新统沉积物主要来自长江流域中、下游的近源物源区,而第四系沉积物的物源虽然存在一定的变化,但是总体上与上新统沉积物来源明显不同,主要来自更广泛的流域物源区,尤其是长江上游的风化物质被大量输运到河口三角洲地区。在第四纪构造和气候因素控制下,古长江水系具有不同的演化阶段,流域源岩经历的风化作用强度也不同,因此河流沉积物的源汇过程也相应地发生变化。     

Geochemistry of rare earth elements in the mainstream of the Yangtze River,China

Water, suspended matter, and sediment samples were taken from 8 locations along the Yangtze River in 1992. The concentration and speciation (exchangeable, bound to carbonates, bound to Fe–Mn oxides, bound to organic matter, and residual forms) of rare earth elements (La, Ce, Nd, Sm, Eu, Tb, Yb, and Lu) were determined by instrumental neutron activation analysis (INAA).The contents of the soluble fraction of REEs in the river are low, and REEs mainly reside in particulate form. In the particles, the chondrite-normalized distribution patterns show significant LREE enrichment and Eu-depletion. While normalized to shales, both sediments and suspended matter samples show relative LREE enrichment and HREE depletion. REEs are relatively enriched in fine-grained fractions of the sediments.The speciation characteristics of REEs in the sediments and suspended matter are very similar. The amount of the five forms follows the order: residual>>bound to organic matter∼bound to Fe–Mn oxides>bound to carbonates>>exchangeable. About 65 to 85% of REEs in the particles exist in the residual form, and the exchangeable form is very low. High proportions of residual REEs reveal that REEs in sediments and suspended matter are controlled by their abundances in the earth's crust. Carbonate, Fe–Mn oxide and organic fractions of REEs in sediments account for 2.4–6.9%, 5.2–11.1%, and 7.3–14.0% of the total contents respectively. They are similar to those in the suspended matter. This shows that carbonates, Fe–Mn oxides and organic matter play important roles during the particle-water interaction processes. By normalization to shales, the 3 forms of REEs follow convex shapes according to atomic number with middle REE (Sm, Eu, and Tb) enrichment, while light REE and heavy REE are depleted.     

河流稀土元素地球化学研究进展

河流系统中,稀土元素(REE)受区域地质背景、风化作用、溶液化学以及水与颗粒物相互作用等因素的影响发生分异。河流悬浮物显示轻稀土(LREE)适度富集;河水显示重稀土(HREE)富集,或在HREE富集的基础上又有适度的中稀土(MREE)富集;与其它微量元素相比,REE在河水与颗粒物之间有较小的分配系数(K≈10-6);河流沉积物多显示平坦的REE配分模式。