Rare earth elements in soil and in soil-grown plants

Concentrations of the rare earth elements (REEs) La, Ce, Nd, Sm, Eu, Gd, Tb, Yb and Lu were determined in leaves of 6 plant species (Norway spruce, silver fir, maple, ivy, blackberry, and wood fern), and in pertinent soils and soil extracts, also taken from the same site. The distribution of the individual REEs in plants showed little or no agreement with that in the soil or the soil extracts. Ce had a negative anomaly with respect to the soil in all plants. The REE distribution patterns of fir and spruce were almost identical, but differed profoundly from that of the other species. In most cases, concentration ratios between species were a smooth function of the atomic number of the REE. Very similar results were obtained at 2 additional sites.     

Rare earth elements in soil and plant systems - A review

The rare earth elements (REEs) form a chemically uniform group and include yttrium (Y), lanthanum (La) and the lanthanides cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu). Their average abundance in the Earth’s crust range from 66μg g⁻¹ in Ce to 0.5μg g⁻¹ in Tm and ?0.1μg g⁻¹ in Pm. Recent great improvements in more routine analytical technique, the use of REEs as fertilisers, at least in East Asian agriculture, and the importance of these elements as indicators in both pedological and physiological processes and reactions have contributed to an increased interest in these previously less considered elements in environmental sciences. This review of recent and current literature deals with REEs in primary and secondary soil minerals, concentrations in surface soils, factors influencing adsorption, solubility and transport in soils, including weathering and transformations of REE minerals, and vertical distribution in soil profiles. Reviewed and discussed are also concentrations, distribution and localisation of REEs in plants and plant organs, soil-plant relationships and interactions, effects on plant growth and crop production and their importance in plant physiology and biochemistry. The REEs are found, usually several elements together, as phosphates, carbonates and silicate minerals finely dispersed especially in magmatic and metamorphic rocks. REE concentrations in surface soils of humid climates, such as the A(E)-horizons of Podzols and Laterites, are usually lower than in the parent material, due to higher weathering and leaching rates than of the average soil constituents. Some fractionation may occur due to the formation of more element-specific secondary minerals. Transfer from soil to plant is usually low, but extreme accumulators are found, e.g., among several species of ferns. Roots have generally higher concentrations than shoots. Possible uptakemechanisms of REEs are discussed. Uptake is positively, though often weakly, correlated with soil acidity and easily soluble concentrations of the elements, but rarely well related to their total concentrations in the soil. Under certain conditions, low concentrations of at least some REEs seem to favour plant growth and productivity, but the physiological mechanisms are still not well understood. Some considerations concerning the boundary between essential and non-essential micro nutrients are discussed.     

Rare earth elements in forest-floor herbs as related to soil conditions and mineral nutrition

Mixtures of rare earth elements (REEs) in fertilizers are widely used in Chinese agriculture to improve crop nutrition. REE concentrations in wild-growing plants, especially herbs, are little known. This study describes differences in the concentrations and proportions of REEs in eight forest-floor herbaceous plants and relates these differences to soil and mineral nutrient conditions. REEs studied were yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu). Leaf concentrations of sum REEs differed more than one order of magnitude between species, being highest in Anemone nemorosa (10.1 nmol/g dry mass) and lowest in Convallaria majalis (0.66 nmol/g) from the same site. Leaf concentrations of all REEs correlated positively (p<0.001), as did sum REE with calcium (Ca) and strontium (Sr) concentrations (p<0.001). A negative relationship (r=−0.83, (p<0.001) was measured between phosphorus (P) concentrations and sum REE concentrations in leaves. However, the proportions of the single REEs in the REE sum differed among species. In A. nemorosa, 57% of the molar REE sum was taken by Y+La, and only 21% by Ce. The other extreme was Maianthemum bifolium, with 37% La+Y and 41% Ce. These two species had 2.7–3.0% of the REE sum as heavier lanthanides, compared to 4.1–5.2% in the six other species. No clear relationship between soil properties or REE contents and leaf REE concentrations was detected. For La, however, an overrepresentation in leaves prevailed throughout all species compared to soils, whereas particularly Nd, Sm, and Tb had a lower proportion in the leaves of all species than in their soils. Possible uptake mechanisms of REEs in plants are discussed.     

Rare earth and yttrium elements (REY) patterns of mesostructures of Miaolingian (Cambrian) thrombolites at Jiulongshan,Shandong Province,China

The relationship between the thrombolitic mesostructures and their depositional environments is still poorly understood due to inconsistent results by sedimentary investigation. Rare earth elements plus yttrium (REY) in ancient microbialites have been extensively applied to paleoenvironmental studies owing to their fractionation in different depositional environments. In order to investigate the environmental controls on thrombolitic mesostructures, we present the REY concentrations and patterns of four types of mesostructures of the Miaolingian (Cambrian) thrombolites in the Changhia Formation at the Jiulongshan section, Shandong Province, China. The REY compositions of those thrombolites show two distinctive groups: (1) light REY depleted patterns with negative Ce anomalies in spotted (SM) and layered mesostructures (LM) of thrombolites; and (2) flat patterns with weak Ce anomalies in dendritic (DM) and meshed mesostructures (MM) of thrombolites. Controlling factors analysis reveals that terrigenous detritus inputs have stronger influence on REY in SM and LM. In contrast, early diagenetic porewaters from underlying sediments have more serious impacts on REY concentrations and patterns in DM and MM. Our results clearly indicate that SM and LM were formed under oxic marine settings with minor terrigenous inputs, whereas DM and MM formed under suboxic marine settings suffered from early diagenetic porewater from underlying sediments. This new geochemical evidence suggests that thrombolitic mesostructures were strongly influenced by paleoenvironment, and REY of thrombolites with controlling factors analysis can be utilized as effective proxies for paleoenvironments.     

Concentration and composition of dissolved organic carbon in streams in relation to catchment soil properties

Two adjacent catchments in the Otway Ranges of Victoria, Australia (Redwater and Clearwater) produce water with markedly different concentrations of dissolved organic carbon (DOC) during summer. Water from Redwater Creek had a DOC concentration of 32 mg L^–1, while water from Clearwater Creek had a DOC concentration of 3.8 mg L^–1. Examination of the catchments revealed that while climate, topography, vegetation and land use were similar, the soils were different. The objective of this study was to examine the relationship between the concentration and chemical composition of DOC in stream waters and the nature of soils in the two catchments. Soil mapping determined that clayey soils formed on Cretaceous sediments (Cretaceous soils) occurred throughout both catchments, but that Redwater Catchment also contained a large area (39%) of sandy soils formed on Tertiary sediments (Tertiary soils). The concentration of DOC in forest floor leachate was high in both the Tertiary and Cretaceous areas; however, the concentration of DOC in water draining areas dominated by Tertiary soils was greater than that in water draining areas dominated by Cretaceous soils. Laboratory experiments showed that the Cretaceous soils had higher adsorption capacities for forest floor leachate DOC than the Tertiary soils. The difference in DOC concentrations of the streams was therefore attributed to the difference in adsorption capacity of catchment soils for DOC. Adsorption capacities of the soils were found to be a function of their clay contents and specific surface areas.Solid-state³C nuclear magnetic resonance spectroscopy and pyrolysis-mass spectrometry were used to determine the chemical structure of DOC found in streams and forest floor leachate samples and that remaining in solution after interaction with soil. Chemistry of DOC in forest floor leachate was similar before and after interaction with soil, indicating no preferential adsorption of a particular type of carbon. Thus, differences between the chemical structure of stream DOC and forest floor leachate DOC could be attributed to microbial modifications during its movement through soils and into the streams, rather than losses by adsorption.     

长期喷施稀土对土壤-植物(小麦)系统中稀土元素分布、累积及运移的影响

在我国施用稀土时间最长的黑龙江省花园农场,研究比较了施用稀土12 a和不施稀土的对照处理上小麦和土壤中的稀土元素的分布、累积及运移.结果表明,长期叶面喷施稀土并未造成耕层土壤和下部土层的稀土元素的累积.成熟期小麦植株各部位的稀土元素含量顺序为根>叶>茎、壳;稀土元素主要累积在根部,其次是叶,茎和壳累积较少.喷施处理小麦根部的稀土元素累积量高于对照,叶部也有此趋势,而茎、壳等部位差异不大.根、茎、叶、壳稀土元素分布模式与土壤中相似,与施用的常乐稀土差别较大;长期喷施稀土未曾造成籽粒中稀土元素的明显累积.     

The Rengen Grassland Experiment: relationship between soil and biomass chemical properties, amount of elements applied, and their uptake

The Rengen Grassland Experiment (RGE) was established in the Eifel Mountains (Germany) on a low productive Nardetum in 1941. Since then, the following fertilizer treatments have been applied with a late two-cut system: unfertilized control, Ca, CaN, CaNP, CaNPKCl and CaNPK₂SO₄. We aimed to understand how concentrations of macro (N, P, K, Ca and Mg), micro (Cu, Fe, Mn and Zn) and trace (As, Cd, Cr, Ni and Pb) elements in the plant biomass were affected by long-term fertilizer application, soil chemical properties and biomass production. In 2008, biomass samples from the first cut (early July) and the second cut (mid-October) were collected and analyzed. The simultaneous application of N, P and K decreased nitrogen concentration in the aboveground biomass, but substantially increased biomass production. Late cutting management decreased forage quality in highly productive more than in low productive plant communities. The concentrations of P and K in the plant biomass were positively related to P and K application and, therefore, to plant available P and K concentrations in the soil. The concentrations of some micro (Fe, Mn and Zn) and trace (As, Cd, Cr, Ni and Pb) elements in the plant biomass were negatively correlated with the amount of elements supplied by fertilizers and biomass production, probably because of the dilution effect. Long-term fertilizer application resulted in the accumulation of macro (P, Ca and Mg), micro (Fe and Mn) and trace (As and Cr) elements in the soil, but in many cases this accumulation was not connected with an increase in the concentrations of these elements in the plant biomass. Nutritional status, as indicated by the biomass N:P ratio, was consistent with N or P limitation as indicated by the nitrogen and phosphorus nutrition indices. Furthermore, additional K (co-)limitation was indicated by the N:K and K:P ratios in the biomass from the NP treatment. The results from the RGE indicate that there is no simple positive relationship between the applied elements and their concentrations in the plant biomass.     

Relationships between Population Size, Genetic Diversity and Fitness Components in the Rare Plant Dictamnus albus in Central Germany

An increasing number of studies support the hypothesis that smaller populations face a higher risk of extinction, and declining population sizes are therefore one of the focal points in plant conservation. In small populations, loss of genetic diversity is often related to reduced reproductive fitness. For the rare Dictamnus albus in Central Germany, an earlier study had already confirmed a significant correlation between population size and genetic diversity. In order to assess whether these variables correlate with fitness components, plant height; flower, fruit and seed production; and germination were studied in a total of 11 populations of different size. In the seven populations that were sampled over two consecutive years, differences among populations and among years were tested using a Two-Way ANOVA. Co-linearity among variables was assessed using principal component analysis (PCA), followed by calculating correlations between ordination axes and both population size and genetic diversity. Plant height and flower number were uncorrelated to the other variables and, together with germination, did not show any correlation to either population size or genetic diversity. However, both size and genetic diversity of populations correlated significantly with other PCA axes that reflected reproductive components such as fruit number, seed number, seed fruit ratio, and seed mass. Our results support the idea that reproduction is hampered in small populations and raise concerns over the loss of genetic diversity in D. albus.     

稀土元素对土栖动物群落结构的影响及对蛴螬的生态毒性

采用土施法和OECD推荐的滤纸接触法研究了稀土(ReCl₃·6H₂O)对豆田土栖动物群落结构的影响以及稀土对蛴螬的生态毒性.结果表明,对照与各处理之间动物种类数、主要动物种群数量、多样性指数差异均不显著;急性和慢性毒性试验表明,对照与各处理间的死亡率差异不显著.在稀土有效施用范围内,稀土对蛴螬的生态毒性很小,不会明显改变蛴螬种群结构.     

Rare earth elements (REEs) in PM10 and associated health risk from the polymetallic mining region of Nandan County,China

A total of 26 samples were collected from Dachang, Chehe and Liuzhai in Nandan County, China, in order to investigate the concentrations of rare earth elements (REEs) and associated health risk in particulate matter. The concentrations of REEs in Dachang (23.54 ng/m³), Chehe (20.29 ng/m³) were significantly higher than those in Liuzhai (8.1 ng/m³). The light rare earth elements (LREEs) account for 87.08%, 87.09%, and 86.17% of the total REE burden in PM10 at Dachang, Chehe, and Liuzhai, respectively, indicating that the distribution pattern of REEs in PM10 was characterized by the obvious fractionation of LREEs. Enrichment factor calculation indicated that EFs for La, Ce, Nd, Pr, and Nd in PM10 from Dachang and Chehe were greater than 2, indicating moderate enrichment. Source identification indicated that REEs in PM10 from Dacheng and Chehe originated from anthropogenic activities such as mining and smelting activities, while REEs in PM10 from Liuzhai were associated with natural sources, like soil erosion. Noncarcinogenic and carcinogenic risks associated with the exposure of REEs in PM10 were negligible based on the health risk assessment models. However, greater noncarcinogenic risk for children was found in studied areas compared with the adults.     

携带污染物降解基因的可移动基因元件及其介导的生物修复

可移动基因元件(mobile genetic elements,MGEs)在环境微生物群落中的水平转移是细菌基因组进化和适应特定环境压力的重要机制.在污染土壤和水体中接种携带具有降解基因MGEs的菌株后,随着MGEs的水平基因转移,可使降解基因转移至具有竞争性的土著微生物中并在其中表达,从而不必考虑供体菌在环境中是否能够长期存活.这种由可移动降解基因元件水平转移介导的生物修复为探索新的生物修复途径提供了可行性.本文重点综述了环境样品中携带降解基因MGEs的多样性及其在促进污染物降解过程中的重要作用,介绍了从环境样品中分离代谢MGEs的方法,并列举了在污染土壤、活性污泥、其他生物反应器等生态系统中MGEs水平转移的几个实例.     

Rare earth element, Al, and Sc partition between soil and Caatinger wood grown in north-east Brazil by instrumental neutron activation analysis

Seven representative wood species constituting Caatinger forest in north-east Brazil were chosen to analyze La, Ce, Sm, Eu, Yb, Sc, and Al by instrumental neutron activation analysis (INAA). Soil profiles were prepared where the trees were downed. Then soil and root samples from each horizontal soil layer, as well as the upper part of the wood, ground-level bark, and the bark at 1 m above were collected. In woods, the rare earth element (REE) was found to be mainly accumulated in root, which concentration was in the same order as that of soil. In all samples, concentration of La and Ce were found to be about ten times higher than those of the other REEs. The REE accumulation became higher, in both root and soil, in the order of La, Ce, and Sm. The partition rate of La and Eu was higher from soil to root, whereas Ce tended to be concentrated from root to bark. In the case of bark, there was no tendency of specific REE accumulating from ground level to the upper part. The correlation of La concentration to the other REE was higher in root than that of corresponding soil. Roots also showed higher correlation of REE to Al and Sc than that of soil or bark.     

Damage in beech forests of Schleswig-Holstein (Northern Germany) in relation to forest structure and soil conditions

The knowledge of the relationship between plant communities and soil types presents a valuable interpretation base for damage assessment. As expected, trees growing on unfavourable sites (e.g. on soils with impeded water) react more sensitively to secondary stress factors such as air pollutants than trees on suitable sites. With a declining nutrient supply in the series Elymo-Fagetum, Asperulo-Fagetum, Violo-Quercetum we recognize a corresponding increase of the damage level in the tree layer of these forest communities. However, ecological site parameters are not always sufficient for an explanation of the high damage level of some communities. It is supposed that a specific structure of these communities is responsible for a considerable proportion of severely damaged trees. Particular crown integration in the tree layer of forests and damage levels are closely connected. The influence of forest structure therefore masks the damage components affected by soil conditions.     

南方稀土采矿恢复地土壤稀土元素含量及植物吸收特征

通过野外取样调查和室内ICP-MS测定,研究了福建省长汀县稀土矿治理地土壤和主要植物中稀土元素的含量、分布以及转移特征.结果表明:稀土矿治理地的土壤养分含量较低;土壤中稀土元素的含量为507.40～841.37 mg· kg-1,高于对照地土壤的含量.稀土矿治理地土壤中稀土元素主要为交换态,其含量占总量的61％～98％.稀土矿治理地土壤中稀土元素从原来偏单一的交换态转变为多种形态共存,其中有机态含量显著升高.植物根、茎、叶中稀土元素含量分别为40.27～986.01、5.14 ～ 206.58、6.81 ～ 2364.51mg·kg-1.稀土元素在植物各器官中含量水平除芒萁为叶＞根＞茎,其他植物均表现为根＞叶＞茎.根据不同植物吸收和积累稀土元素的差异,可将矿区治理地植物分为富集型和根部囤积型植物.芒萁属于富集型植物,桉树、高羊茅、宽叶雀稗、木荷和油茶属于根部囤积型植物.     

Density and population estimate of gibbons (Hylobates albibarbis) in the Sabangau catchment, Central Kalimantan, Indonesia

We demonstrate that although auditory sampling is a useful tool, this method alone will not provide a truly accurate indication of population size, density and distribution of gibbons in an area. If auditory sampling alone is employed, we show that data collection must take place over a sufficient period to account for variation in calling patterns across seasons. The population of Hylobates albibarbis in the Sabangau catchment, Central Kalimantan, Indonesia, was surveyed from July to December 2005 using methods established previously. In addition, auditory sampling was complemented by detailed behavioural data on six habituated groups within the study area. Here we compare results from this study to those of a 1-month study conducted in 2004. The total population of the Sabangau catchment is estimated to be about in the tens of thousands, though numbers, distribution and density for the different forest subtypes vary considerably. We propose that future density surveys of gibbons must include data from all forest subtypes where gibbons are found and that extrapolating from one forest subtype is likely to yield inaccurate density and population estimates. We also propose that auditory census be carried out by using at least three listening posts (LP) in order to increase the area sampled and the chances of hearing groups. Our results suggest that the Sabangau catchment contains one of the largest remaining contiguous populations of Bornean agile gibbon.     

Mustelids from Sackdilling Cave (Bavaria,Germany) and their biostratigraphic significance

Sackdilling Cave is a karst fissure filled with a fossiliferous breccia including abundant fossil remains, mostly snails and small mammals. The taxonomic status of mustelid remains from this cave was previously regarded as controversial and, consequently, different authors listed different species from the locality. A detailed revision of the material shows the presence of five mustelid species: Meles sp., Martes vetus, Mustela strandi, Mustela palerminea, and Mustela praenivalis. Among them, especially noteworthy is the presence of the type specimen of Martes vetus. The Sackdilling holotype resembles Martes foina and differs from that of Martes martes in a short and broad viscerocranium; wide and less extended forward incisor row; compressed, short and wide temporal region; large, strongly inflated and convex tympanic bullae; and narrow P3 with weak lingual bulge. Some dental characters are specific for Martes vetus and show some intermediate values between Martes foina than Martes martes. Among them are the P4 protocone length and the M1 trigon length. The revised material from Sackdilling Cave of Mustela palerminea and Mustela praenivalis was compared with that from other Early and early Middle Pleistocene sites of Europe and showed the presence of intermediate characters. Subsequently, based on the entire mustelid assemblage and other faunal elements (mainly rodents), the age of this fauna was estimated as ca. 0.9–0.7 Ma.     

镉的致癌性与食品中镉的生物有效性

镉(Cd)因其广泛的环境污染而成为20世纪人类关注的一种重金属。虽然现在仍不知道镉具有的生理功能,但有证据表明镉是一个具有生物活性的金属。一般人镉暴露的主要途径食品摄入,其次饮水等途径。尽管一些地方病的证据有力支持了镉潜在的致癌特性,但由于环境中化学物质和吸烟等生活习惯与镉暴露之间存在难以区分的致病影响,使镉致病的研究得出了并不一致的结论,引起了镉致癌性的争论。该文通过对人类镉暴露的文献综述,试图理解土壤、食品中镉的生物有效性与疾病,特别是致癌性的关系。值得强调的是文献报道人体内营养元素铁(Fe)、锌(Zn)和钙(Ca)浓度的提高,对减少镉的吸收、减轻镉中毒都具有重要的作用,这也许是我们彻底解决人类镉暴露风险的突破口。     

Linear relation between leaf xylem water potential and transpiration in pearl millet during soil drying

Plant and Soil - Populus can tolerant high concentration Al stress. However, the mechanisms of Mg alleviation to Al toxicity in populus remain unknown. In the present study, adequate Mg was...     

Concentration of 17 trace elements in serum and whole blood of plains viscachas (Lagostomus maximus) by ICP-MS, their reference ranges, and their relation to cataract

The reference ranges of the trace elements Al, As, Be, B, Cd, Co, Cu, Fe, Mn, Mo, Ni, Pb, Li, Rb, Se, Sr, and Zn were determined by inductively coupled plasma-mass spectrometry (ICP-MS) in sera of a group of free-ranging plains viscachas of the pampa grasslands of Argentina. The values were compared with those of a small group of captive plains viscachas of the Zurich Zoo with diabetes and bilateral cataracts. In addition, a method for digestion of whole-blood samples is described for the trace element determination. Significant differences in the concentration of trace elements in the two groups of animals are discussed. No correlation was found between the levels of selenium and of other trace elements compared to the formation of cataracts.     

Antineoplastic potential of curcumin (cooperative study in Bulgaria and Germany)

The unfavorable safety of existing anticancer medications and the issue of multidrug resistance have fuelled the search for novel plant compounds as potential antineoplastic agents. One of the used approaches for identifying perspective candidates is based on ethnopharmacology. Curcumin is the yellow pigment of curry and has being employed in traditional Indian medicine. Within the EU it has the status of food ingredient (E100) and remains in many food additives. It is isolated from Curcuma longa L. and has been reported as NF-κB inhibitor and apoptosis inducer with antioxidant, cholesterol lowering, anti-inflammatory, anti-parasitic, antibacterial and antitumor potential. Curcumin has been shown to exert a wide spectrum of pleiotropic activities including antitumor effects and protection of the normal bone marrow. It possesses antineoplastic activity in various malignant cell lines in vitro, such as cutaneous T cell lymphoma, acute myeloid leukemia and urinary bladder cancer cells. In lymphoma and leukemia cell lines curcumin induces apoptosis as evidenced by caspase activation, PARP cleavage and oligonucleosomal DNA fragmentation. Expression of the myeloid marker CD13 (aminopeptidase N) is associated with faster apoptosis induction. In addition, curcumin causes concentration-dependent glutathione level increase. Application of curcumin in vivo resulted in protection against cisplatin-induced chromosomal aberrations (anticlastogenic effect). This finding reveals curcumin as preferable partner for combinations with antineoplastic agents in order to potentiate their activity and ameliorate the adverse effects. There is a clear need for new curcumin formulations because of its low bioavailability after oral intake. Cutaneous and intravesical curcumin applications remain a possibility for successful clinical use of curcumin.