Variation of the rare earth element concentrations in the soil, soil extract and in individual plants from the same site

Samples of various types (spruce needles, blackberry leaves, soils, and soil extracts) have each been taken at 6 places from the same site. In addition, 4 whirls each from 2 spruce trees were sampled. Rare earth elements (REEs) were determined in these samples by neutron activation analysis with a chemical group separation. Variations between places were found to be small with soils and soil extracts, but large with plants. Variations between whirls were small. Plants neither reflected the soil nor the soil extract. Both plant species were dissimilar, but the logarithm of their ratio was a linear function of the atomic number of the REE. A negative Ce anomaly (with respect to soil) was found in both plant species.     

Concentration levels of rare-earth elements and thorium in plants from the Morro do Ferro environment as an indicator for the biological availability of transuranium elements

Plants and soils from a natural thorium and rare-earth element occurrence (Morro do Ferro, Brazil) were analyzed by alpha spectrometry (Th) and ICP-AES (REE), after pre-concentration of the elements by solvent extraction, co-precipitation and ion exchange procedures. Leaching experiments with humic acid solutions and different soils were performed to estimate the fraction of elements biologically available. High concentrations of the light rare-earth elements (LREE) and of Th, reaching some hundreds of g/g-ash, were measured in plant leaves from the areas of the highest concentration of these elements in soil and in near-surface waters. Chondrite normalized REE plots of plant leaves and corresponding soils are very similar, suggesting that there is no significant fractionation between the REE during uptake from the soil solution and incorporation into the leaves. However, Ce-depletion was observed for some plant species, increasing forSolanum ciliatum in the sequence: leaves<fruits<seeds. Soil to plant concentration ratios (CR's) for Th and the REE, based on the total concentration of these elements in soils, are in the range of 10^–3 to 10^–2. Leaching experiments confirmed the importance of humic acid complexation for the bio-uptake of Th and REE and further showed that only a very small fraction of these elements in soil is leachable. The implications of these results on the calculated CR's will be discussed.     

Distribution characteristics of rare earth elements in plants from a rare earth ore area

The contents of eight rare earth elements (La, Ce, Nd, Sm, Eu, Tb, Yb and Lu) in various plant species taken from a rare earth ore area were determined by instrumental neutron activation analysis. For a given plant, the REE patterns in root, leaf and host soil are different from each other. The REE distribution characteristics in roots of various species are very similar and resemble those in the surface water. The results of this study suggest that there is no significant fractionation between the REEs during their uptake by the plant roots from soil solution. However, the variation of the relative abundance of individual REE occurs in the process of transportation and deposition of REEs in plants.     

Major and Trace Elements in Spruce Needles from Urban Areas: Some Aspects of Analysis in Environmental Studies

Main and trace elements in samples of spruce needles from urban areas in Poland and Norway were analysed using the ICP-AES method. Concentrations of Al, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, P, Sr, Ti, V and Zn were measured in needles from conifer trees growing in different locations. Two different procedures of laboratory sample preparation were compared and discussed. Different washing procedures were examined and compared. For quality control of analytical measurements, Standard Reference Material BCR CRM 101 (spruce needles from Europe) was used. Synergistic and antagonistic relationships between elements in spruce needles were investigated. Applicability of spruce needles in biomonitoring of environmental metal pollution was discussed.     

Determination of the contents and distribution characteristics of REE in natural plants by NAA

The concentration of 8 REEs (La, Ce, Nd, Sm, Eu, Tb, Yb and Lu) in 17 species of plants and their host soil, which were collected from a rare earth ore area located in the south of China, have been determined by INAA. The chondritic normalized REE patterns for different parts of plants (e.g., leaf stem and root) and their host soils were studied. The results showed that the concentration levels of REE for most plants in the sampling area were elevated. Particularly, the leaves of the fern (Dicranopteris dichotoma) contain extremely high concentration of the total REE (675–3358 g/g) Generally, these REE distribution patterns in every part of plants were very similar and reflected the characteristics of their host soils. However, the chondritic normalized REE patterns in some plants relative to the host soil revealed obvious fractionation, such as the depletion of the heavy REE (for fernCitrus reticulata andBrassia campestris), the heavy REE enrichment (forCamellia sinensis, Camellia oleifera andZiziphus) and the Ce positive anomaly (forGardenia jasminoides).     

Arsenic concentrations in successive needle age classes of Norway spruce ( Picea abies [L.] Karst.)

Arsenic has been determined in needles of Norway spruce by neutron activation analysis. Trees from 8 sites grown under different soil and environmental situations have been sampled. Trees and needle age classes have been treated individually. Endogenous As concentrations in needles <100 ng/g have been detected. Concentrations increased linearly with the needle age class. This biodynamic behaviour is attributed tentatively to a predominant foliar uptake. Concentrations at the various sites differed by a factor of 7. No connection could be found between As concentrations in needles and total As in the soil or pH of the soil. However, the strong correlation between the endogenous and the exogenous concentrations, and differences of As concentrations in needles between different sites are thought to be due mainly to different inputs of As from the atmosphere.     

Arsenic concentrations in successive needle age classes of Norway spruce (Picea abies [L.] Karst.)

Arsenic has been determined in needles of Norway spruce by neutron activation analysis. Trees from 8 sites grown under different soil and environmental situations have been sampled. Trees and needle age classes have been treated individually. Endogenous As concentrations in needles <100 ng/g have been detected. Concentrations increased linearly with the needle age class. This biodynamic behaviour is attributed tentatively to a predominant foliar uptake. Concentrations at the various sites differed by a factor of 7. No connection could be found between As concentrations in needles and total As in the soil or pH of the soil. However, the strong correlation between the endogenous and the exogenous concentrations, and differences of As concentrations in needles between different sites are thought to be due mainly to different inputs of As from the atmosphere.     

Determination of the Contents and Distribution Characteristics of Rare Earth Elements in Solanum lycocarpum from Tropical Ecosystems in Brazil by INAA

We have determined the concentrations of eight REE elements by instrumental neutron activation analysis (INAA) (La, Ce, Nd, Sm, Eu, Tb, Yb, and Lu) in plant leaves of the species Solanum lycocarpum, a typical Brazilian "cerrado" plant widely distributed around the country, and in the soils in which they grow. Three different ecosystems were studied. Very similar chondrite normalized patterns were observed in the soil and in the plant, presenting an enrichment of the light REE, indicating a typical absorption of these elements by this species.     

Distribution patterns of rare-earth elements in biological materials evaluated by radiochemical neutron activation analysis

This study deals with the quantitative determination of eight REE's viz, La, Ce, Nd, Sm, Eu, Tb, Yb, and Lu as an Integral part of a post-irradiation chemical separation scheme for the determination of 14 trace elements in biological materials. REE values are given for NBS Orchard Leaves SRM 1571, NBS Bovine Liver SRM 1577 and Bowen's Kale, as well as for some other biological (reference) materials of plant, animal and human origin. Chondritic-normalized REE patterns of these materials are discussed. It is shown that differentiations in REE-pattern between soil and plant may occur, and also that within the human body different modes of fractionation of REE's take place.     

Transfer of technetium in the soil-rice plant system

In order to assess the behavior of Tc in flooded soil-plant systems, laboratory experiments have been done using^95mTc as a tracer. Two common soil types in Japan, Andosol and Gray lowland soils, were used. Soil-plant transfer factors of Tc in rice grain were very low, i.e. 5×10^–5 for Andosol and 6×10^–4 for Gray lowland soil. It was found that the Tc concentrations in rice plants were influenced by those in soil solutions. Concentrations of^95mTc in both soil solutions decreased rapidly in the early period of cultivation. It was observed that redox-potential (Eh) also decreased markedly following flooding. A relationship was found between the decrease of the^95mTc concentrations in soil solutions and the drop of Eh in the soils. The Tc (VII) added to soil was transformed to insoluble Tc (IV) under the reduced conditions existing in flooded soil.     

土壤发育过程中稀土元素的地球化学指示意义

研究了海南岛北部不同时期喷发的玄武岩上发育土壤中稀土元素的地球化学特征和行为,探讨成土元素的分异及其对土壤发育程序的指示作用。ＲＥＥ总量与成土年龄呈显著正相关,是指示土壤发育程序的良好指标。同时,随土壤发育程度的加深,ＲＥＥ出现分异,土壤中轻稀土逐渐富集,重稀土亏损,伴随的进一步发育,Ｃｅ逐渐向正异常而Ｅｕ向负异常方向演化。     

Silicon determination in plant materials by instrumental epithermal neutron activation analysis

The Si determination with epithermal neutrons using the reaction²⁸Si (n,p)²⁸Al is described. Thermal neutrons are eliminated from the irradiation position with a BN-shield. Two first order interfering reactions with P and with Al necessitate appropriate corrections. The interfering reaction on Al is shown to depend heavily on the hydrogen (H) content of the sample, which therefore must be taken into account. The lower application range in plant samles is estimated to be 500 g g^–1. Reproducibility is <5% in suitable cases, but not as good if the necessary corrections are large. The capacity is 25 samples per 8 h. The method is applied to 3 plant standards (rice, hay and pine needles) and to 47 samples of spruce needles. The applicability to different plant materials is mainly limited by their relative Al, P and Si concentrations. Literature values are use to find plant categories in which Si can be reasonably determined by instrumental epithermal neutron activation analysis (IENA).     

Distribution of rare earth elements in the estuarine and coastal sediments of the Daliao River System, China

The Daliao River System (DRS) estuary in Liaodong Bay features a highly industrial, urbanized, and agricultural catchment. The objective of this study was to determine the content, behavior, and distribution of the rare earth elements (REEs) in the estuarine and coastal sediments. To this end, 35 sediment samples were collected from the estuarine and coastal area and analyzed for REEs, Fe, Al, and Mn. The mean concentrations in mg kg^?1 of the sediments were 33.4 (La), 64.1 (Ce), 7.9 (Pr), 29.0 (Nd), 5.4 (Sm), 1.2 (Eu), 4.2 (Gd), 0.78 (Tb), 4.0 (Dy), 0.84 (Ho), 2.3 (Er), 0.40 (Tm), 2.3 (Yb), and 0.37 (Lu). The REE concentrations in the sediments were significantly correlated with one another (r ²  = 0.959–0.988) and the concentrations of Fe, Al, and Mn (r ²  = 0.768–0.870). The total concentration ∑REE ranged from 73.5 to 203.5 mg kg^?1, with an average of 156.0 mg kg^?1 being observed, and generally higher in the estuarine sediments than in the coastal sediments, most likely due to the salt-induced coagulation of river colloids and subsequently their accumulation at the estuarine bottom. The ratio of light REEs (∑LREE) to heavy REEs (∑HREE) was 9.4. Chondrite-normalized REE distributions were observed to be similar for the estuarine and coastal sediments, riverine suspended particles, and watershed soils of the DRS with higher LRRE enrichment than HREE and greater Eu depletion than Ce depletion. These results demonstrate that neither geochemical processes that carry soils to estuarine sediments nor long-term industrial and agricultural activities alter the distribution or fractionation of the REEs in the study area.     

Analysis of terpenoic composition of conifer needle oils by steam distillation/extraction,gas chromatography and gas chromatography-mass spectrometry

Summary The essential oils of Estonian spruce and pine needles have been analysed by a combination of steam distillation/extraction, GC and GC-MS. According to their monoterpene composition Estonian pines belong to a high carene chemotype with monoterpenes representing up to 85% of total oil. Estonian spruce needle oil contains up to 70% of oxygenated terpenes and more limonene and 1,8-cineole than the same spruce species [Picea abies (L.) Karst.] from other localities.A total of 60 components were identified. Coefficients of variation describe the range of component contents in individual trees within the population.     

Rare earth elements determination and distribution patterns in surface marine sediments of the South China Sea by INAA,Malaysia

Results obtained from the analysis of sediments surface samples taken from rivers mouth and polluted marine environment were analyzed for REE contents to determine the concentrations of La, Ce, Sm, Eu, Tb, Dy, Lu and Yb using instrumental neutron activation analysis. Thirty surface samples were collected from ten sites in the coastal marine sediments of the South China Sea along 957 km stretch of the east coast of Peninsular Malaysia. The samples prepared in the powdered form before irradiating them in a neutron flux of ~4 × 10¹² n cm⁻² s⁻¹ at 750 kW power using the TRIGA Mark II research reactor at Malaysian Institute for Nuclear Technology (MINT). Results of the total concentration are used to establish baseline data in environmental pollution assessment and to develop the correlations between the Ce/Ce* anomalies and the distribution patterns of some the light rare earth elements (LREEs) and the heavy rare earth elements (HREEs). The Chondrite-normalized REE pattern from each site examined and used to explain the sedimentation patterns by anthropogenic activities and by natural processes such as shoreline erosion, weathering deposits. Shale-normalized (NASC) patterns suggest enrichment of LREEs relative to the HREEs with a positive Ce/Ce* anomaly. Validation of the used method was done using a Soil-7 SRM.     

An inexpensive, fast, and reliable method for vacuum extraction of soil and plant water for stable isotope analyses by mass spectrometry

The stable isotopes of water (hydrogen and oxygen isotopes) are of utmost interest in ecology and the geosciences. In many cases water has to be extracted directly from a matrix such as soil or plant tissue before isotopes can be analyzed by mass spectrometry. Currently, the most widely used technique for water is cryogenic vacuum extraction. We present a simple and inexpensive modification of this method and document tests conducted with soils of various grain size and tree core replicates taken on four occasions during 2010. The accuracies for sandy soils are between 0.4‰ and 3‰ over a range of 21‰ and 165‰ for δ¹⁸O and δ²H, respectively. Spiking tests with water of known isotope composition were conducted with soil and tree core samples; they indicate reliable precision after an extraction time of 15 min for sandy soils. For clayey soils and tree cores, the deviations were up to 0.63‰ and 4.7‰ for δ¹⁸O and δ²H, respectively. This indicates either that the extraction time should be extended or that mechanisms different from Rayleigh fractionation play a role. The modified protocol allows a fast and reliable extraction of large numbers of water samples from soil and plant material in preparation for stable isotope analyses. Copyright © 2011 John Wiley & Sons, Ltd.     

Determination of thorium and light rare-earth elements in soil water and its high molecular mass organic fractions by inductively coupled plasma mass spectrometry and on-line-coupled size-exclusion chromatography

Inductively coupled plasma mass spectrometry (ICP–MS) has been used for the determination of thorium and light rare-earth elements (LREEs) in soil and soil water samples from a mineral deposit (Morro do Ferro, Minas Gerais, Brazil). Size-exclusion chromatography (SEC) on-line coupled to ICP–MS and UV-detection was applied to verify possible association/complexation of these elements with organic matter in soil water separated by a centrifugation technique. Concentrations of DOC in soil waters are in the range of 10 to 500 mg L^–1 and correlate with the organic carbon content of the soil (r=0.950; p<0.001). Concentrations of 30 to 40 g L^–1 for the LREEs (La, Ce, Nd) and up to 14 g L^–1 for Th were measured in soil waters of highest DOC content. SEC chromatograms of these waters showed the association of elements with different nominal high-molecular-mass ranges, characteristic of soil humic and fulvic acids: >10,000 Da, with a retention time of about 10 min; 7000 to 8000 Da with retention times of 13 to 15 min; and 2000 to 4000 Da with retention times around 23 min. Elemental peaks associated with dissolved organic matter below 1000 Da were not observed, suggesting that complexation with simple plant organic acids or inorganic ligands is of minor importance in the environment studied in this work.     

土壤-植物体系稀土元素的分异现象

用仪器中子活化分析测定了从同一地点采集的9种不同植物根和叶中8个稀土元素（La,Ce,Nd,Sm,Eu,Tb,Yb和Lu)的含量，研究了稀土元素在植物根、叶及相应母土中的分布特征。结果表明，同一植物的根、叶和母土中稀土分布模式均有较大差异。生长在同一地点不同植物根中稀土分布模式非常相似，而叶中分布规模差别较明显。说明根对单一稀土元素的吸收主要取决于这个元素在土壤中有效态的含量，而在稀土从根到叶的运输和积累过程中出现的分异则由植物自身的结构特征决定。     

Rare earth elements determination and distribution patterns in sediments of a polluted marine environment by instrumental neutron activation analysis

Results obtained from the analysis of sediment core samples taken froma fairly polluted marine environment were analyzed for the REE contents todetermine the concentrations of La, Ce, Sm, Eu, Tb, Dy and Yb using instrumentalneutron activation analysis. Core samples were divided into strata of between2 to 3 cm intervals and prepared in the powdered form before irradiating themin a neutron flux of about 5.0 . 10¹² n . cm ^—2s ^—1 in a Triga Mark II reactor. Down-core concentration profilesof La, Ce, Sm, Eu, Tb, Dy and Yb in 3 core sediments from three sites areobtained. The shale-normalized REE pattern from each site was examined andlater used to explain the history of sedimentation by natural processes suchas shoreline erosion and weathering products deposited on the seabed and furnishingsome baseline data and/or pollution trend occurring within the study area.The shale-normalized REE patterns also showed that LREE in the sediment samplesexhibit enrichment relative to HREE particularly, La and Sm showing enrichmentcompared to the ratios in shale. REE concentrations of 124 µg/g at thesurface of sediment collected at two of the three sites were found to decreaseto 58 and 95 µg/g, respectively. This was of particular interest whenit is used to explain the anomalies occurring in the marine sediment as aresult of geochemical processes over a long period of time. Changes in concentrationsfrom surface to bottom of the sediments ratioed to Sm concentrations and thecorrelation between concentrations of Sm and these elements were also investigatedand correlation coefficients were calculated for all REEs and sites. Validationof the method used was done using a Soil-7 SRM.     

Silicon Isotope Fractionation in Maize and its Biogeochemical Significance

Plants that absorb silicon may induce isotope fractionation that causes relative abundance changes in biogeochemical processes in organisms and environment. Silicon isotopes (²⁸Si, ²⁹Si, and ³⁰Si) were determined with high precision using multicollector inductively coupled plasma mass spectrometer. In the present study, the silicon isotope composition was determined in maize and corresponding soil was collected from Zhejiang Province, China. The δ³⁰Si values were from ?2.7 to 3.3‰ in the plant tissues. The isotope fractionation between precipitated and dissolved silicon was 0.9976 and the silicon isotope fractionation in the plants was appeared to be Rayleigh-like process. The fractionation factors between the whole plants and the soil–water-soluble fractions were estimated to be 0.9989, indicating the presence of biochemical silicon isotope fractionation. The active uptake of silicon appeared to play an important role through which the heavy silicon isotopes were preferentially absorbed and transferred to the aboveground plant tissues. However, the roles of a passive mechanism for silicon uptake could not be ruled out through which the light silicon isotopes preferentially precipitated in various plant tissues.