Determination of rare earth, major and trace elements in authigenic fraction of Andaman Sea (Northeastern Indian Ocean) sediments by Inductively Coupled Plasma-Mass Spectrometry

Downcore variation of rare earth elements (REEs) in the authigenic Fe-Mn oxides of a sediment core (covering a record of last ∼ 40 kyr) from the Andaman Sea, a part of the Indian Ocean shows distinctive positive Ce and Eu anomalies. These positive Ce anomalies (Ce* = 1.1 ∼ 1.8) are ascribed to be due to oxidation of deep sea sediments. The large positive Eu anomalies (i.e., Eu* >1.8 to 3.2) occur within a time span near the glacial/interglacial transition (∼ 7000-14,000 yr BP) which could be due to the past hydrothermal activity or to the effects arising from sea level changes. During glacial times, the Andaman Sea was almost completely isolated due to low sea level, leading to a reduction in sediment supply from the Ayeyarwady River. The variations of metal abundances (i.e., Ca, Al, Mn, and Fe) in the authigenic fraction provided independent information to evaluate the water column physicochemical changes during the glacial/interglacial transition period. The studied sediment core records changes in riverine inputs and reflects depositional changes related to sea level fluctuations and climatic events over the past 40 kyr in the Andaman Sea.     

Influencing factors of 90Sr adsorption onto granite fracture filling material in a high-level radioactive waste disposal site

Journal of Radioanalytical and Nuclear Chemistry - A granite fracture filling material (FFM) collected from a candidate high-level radioactive waste (HLRW) geological disposal was used to evaluate...     

Pressurized-fluid extraction (PFE) of chlorinated paraffins from the biodegradable fraction of source-separated household waste

A method is presented in which pressurized-fluid extraction (PFE) is used for the extraction of chlorinated paraffins (CP) from the biodegradable fraction of source-separated household waste. The conditions that were optimized for high recovery in the extraction procedure were extraction time, temperature, and the use of different solvents and different sample particle sizes. Recoveries of CP from fortified household waste material were over 90%, with only few interferences when cyclohexane was used as solvent. Extraction yields from contaminated samples containing CP were further compared with recoveries obtained by use of Soxtec extraction. The results showed that PFE is a rapid, low-solvent-consuming technique, giving high yields. Received: 13 November 2000 / Revised: 2 March 2001 / Accepted: 7 March 2001     

Pressurized-fluid extraction (PFE) of chlorinated paraffins from the biodegradable fraction of source-separated household waste

A method is presented in which pressurized-fluid extraction (PFE) is used for the extraction of chlorinated paraffins (CP) from the biodegradable fraction of source-separated household waste. The conditions that were optimized for high recovery in the extraction procedure were extraction time, temperature, and the use of different solvents and different sample particle sizes, Recoveries of CP from fortified household waste material were over 90%, with only few interferences when cyclohexane was used as solvent. Extraction yields from contaminated samples containing CP were further compared with recoveries obtained by use of Soxtec extraction. The results showed that PFE is a rapid, low-solvent-consuming technique, giving high yields.     

电感耦合等离子体原子发射光谱(ICP-AES)法测定电镀废弃物中的七种元素

采用HCl-HNO3-HF-HClO4体系溶解试料,电感耦合等离子体原子发射光谱法测定电镀废弃物中的钙、铝、镉、钴、铁、锰、镁七种元素含量。通过加标回收实验,这几种元素的加标回收率为96.1%~102%,相对标准偏差均小于3%(n=7),此方法操作速度快、检测效率高,是一种理想的分析方法。     

Geological interactions and radio-chemical risks of primordial radionuclides 40K, 226Ra,and 232Th in soil and groundwater from potential radioactive waste disposal site in Ghana

Journal of Radioanalytical and Nuclear Chemistry - This study assessed the influence of geological depth and formation on activity concentrations of 232Th, 226Ra and 40K in soil and groundwater,...     

µ-X-ray fluorescence and µ-X-ray diffraction investigations of sediment from the Ruprechtov nuclear waste disposal natural analog site

Results from combined µ-XRF and µ-XRD investigations of a uranium-rich tertiary sediment from a nuclear repository natural analog site in Ruprechtov, Czech Republic, are reported. The goal of the investigations is to identify arsenopyrite from diffraction patterns obtained in As-rich areas of the sample. Arsenopyrite has been revealed to be present in the sediment as thin coatings on the surface of Fe nodules from previous µ-XANES results and observed linear dependencies between Fe and As(0) distributions obtained from µ-XRF measurements. In thin sections of the sediment investigated here we find, however, neither diffraction reflections expected for arsenopyrite nor for other As-sulfides. The As(0) phase is likely present in the form of very small grains, or it is amorphous. Statistical analysis of the µ-XRD data using unsupervised classification and principle component analysis from selected sample areas also indicate that pyrite and siderite, but no arsenopyrite, are the sole diffracting phases. That pyrite and siderite are found in the same sample is an indication that the pH of the sediment environment during diagenesis must have been neutral. This allows us to refine our hypothesis for the mechanism of uranium immobilization.     

Safe disposal of diisopropyl fluorophosphate (DFP)

Diisopropyl fluorophosphate (DFP), a volatile highly toxic enzyme inhibitor, in buffer (pH 3, pH 5, pH 7, pH 9, pH 11, Hank’s, Dulbecco’s, PBS, TBE, and HEPES) or water (10 mM), in DMF solution (200 mM), and bulk quantities can be degraded by adding 1M NaOH. The DFP was completely degraded, as determined by enzymatic assay, and the final reaction mixtures were not mutagenic.     

Sorption of manganese(II) and zinc(II) to soils alluvial in origin

The sorption of manganese(II) and zinc(II) on soil samples collected from Sapporo (Japan) and Tiksi (Russia) was investigated using a radiotracer technique to elucidate the abilities of soil organic matter as a scavenger of heavy metals released to the soil environment. The sorbed amounts of both manganese and zinc metals to organic soil components were estimated to be different on different soils, depending on the pH of aqueous phase. The degree of humification of pertinent soils was suggested as a parameter which could describe the properties of the organic soil matter in complexing with heavy metals.     

地球化学模拟在高放废物地质处置中的应用与发展

随着核能事业的发展,高放废物的处理和处置问题日益突出.其中,研究高放废物在环境介质中的吸附、扩散和迁移行为是获取放射性核素对周围环境和人群健康影响的基础参数的最重要和最直接的途径.近年来,人们利用已有的实验数据及核素的基础热力学和动力学数据,附以相应的数学模型,建立了一些地球化学模拟软件,用于分析核素在地质介质中可能发生的连续性和长期性变化.目前,国内外常用的地球化学模拟软件有十多种.本文从热力学平衡计算原理、种态分布计算方法和表面配位模型假设等几个方面对地球化学模拟软件进行了简要介绍,对近年来地球化学模拟软件在核素种态分布计算和表面配位模型模拟两方面的应用进行了举例分析,并以Ca-U-CO3配合物为例,说明完备的热力学数据对地球化学模拟软件发展的重要性,以期促进我国地球化学模型的应用和发展.     

Chemical upcycling of poly(lactide) plastic waste to lactate ester,lactide and new poly(lactide) under Mg-catalysis condition

Chemical upcycling of end-of-life poly(lactide) plastics to lactide, lactate ester and new poly(lactide) has been achieved by using magnesium bis[bis(trimethylsilyl)amide] [Mg(HMDS)₂] as promoter. Mg(HMDS)₂ showed high efficiency in l-lactide polymerization and poly(lactide) depolymerization. Mg(HMDS)₂/Ph₂CHOH catalytic system displayed high ring-opening selectivity and the characteristic of immortal polymerization. Taking advantage of transesterification, depolymerizations of end-of-life poly(lactide) plastics to lactate ester (polymer to value-added chemicals) and lactide (polymer to monomer) were achieved with high yields. Besides, a new “depolymerization-repolymerization” strategy was proposed to directly transform poly(lactide) into new poly(lactide). This work provides a theoretical basis for the design of polymerization and depolymerization catalysts and promotes the development of degradable polymers.     

Trace elements in surface sediments from Kongsfjorden,Svalbard: occurrence,sources and bioavailability

Concentration levels, potential sources and bioavailability of trace elements in marine sediments from Kongsfjorden (Svalbard Islands, Norwegian Arctic) were assessed and discussed. Surface sediments were collected by a Ponar grab and characterised in terms of mineralogical composition, grain-size distribution, total organic carbon and nitrogen percentage contents, and major and trace elements concentrations. Anthropogenic and natural sources of trace elements were inferred from lead isotope ratios, while the potential metal bioavailability was evaluated by size-fractionation and solid-phase speciation studies and by the analysis of acid-volatile sulphides (AVS) and simultaneously extracted metals (SEM). Concentrations of metals, their enrichment factors and solid speciation patterns collectively indicated that the anthropogenic impact of trace elements in the fjord is generally low, with a minor enrichment with respect to crustal values (by a factor of 2–11) for As, Cr, Ni and V. The lead isotope ratios (²⁰⁸Pb/²⁰⁷Pb: 2.474–2.498 and ²⁰⁶Pb/²⁰⁷Pb: 1.206–1.212) were close to the natural signature except in the outer fjord, due to the influence of the Atlantic marine circulation. Many elements of toxicological concern (e.g. Pb, V, Zn) were enriched in the finest sediment fraction, which was by far the preponderant one, especially in the inner fjord. However, less than 15% of most trace elements (exceptions Cd and Mn) in the finest fraction was actually associated with easily leachable sediment phases. Finally, the high SEM/AVS ratios determined on samples from sites close to the glacier fronts (11–15), due to low AVS content, highlighted that the sediment in that zone cannot remove additional inputs of heavy metals by sulphide precipitation.     

Pollution studies of trace elements in sediments from the Upper Saronikos Gulf,Greece

Seventeen trace elements (As, Ce, Co, Cr, Cs, Eu, Fe, Hg, Hf, La Lu, Rb, Sb, Sc, Sm, Yb and Zn) have been determined by Instrumental Neutron Activation Analysis in sediments from the upper Saronikos Gulf, Greece. It was found that the discharge of industrial and domestic wastes in the Keratsini and Elefsis bays of the upper Saronikos Gulf had led to elevated concentrations of all toxic and other trace elements determined over at least 100 km² of seafloor. Increases above natural level range from 2 fold for rare earths to 200 fold for arsenic.     

Trace elements in sediments and bioaccumulation in European silver eels (Anguilla anguilla L.) from a Mediterranean lagoon (SE Italy)

Samples of surface sediments and tissues (liver and muscle) of commercially available European silver eels (Anguilla anguilla L.) collected from Varano lagoon (Italy) were analysed to determine trace element contents. Univariate and multivariate analyses were performed to highlight both the differences between sampling sites and the influence of channel discharges. Atomic ratios indices for sediment data and biological enrichment factors (BEF) for eel tissues were calculated in order to evaluate the enrichment factor due to human activities. The highest levels of As (11.9?µg?g^?1) and Zn (14.1?µg?g^?1) were observed in the south-eastern zone of the lagoon, which is influenced by urban and agricultural discharges. The low levels of Hg observed in this study (0.04?µg?g^?1) led us to exclude both natural and human local sources of this element. Trace element concentrations of all elements were lower in muscle than in liver tissue. Significant enrichment of Cu and Zn was found in livers.     

Investigation of the vertical distribution of major and trace elements in Matita Lake (Danube Delta) sediments by activation analysis

The vertical profiles of two major elements (Na and Ca) and 24 trace elements (Rb, Cs, Sr, Ba, Sc, La, Ce, Sm, Eu, Tb, Yb, Lu, Th, U, Hf, Nb, Ta, Cr, Fe, Co, Zn, As, Sb and Br) have been investigated by neutron activation analysis in a 2.5 m core collected from the Danube Delta, Matita Lake. The data have been correlated with the concentrations of five major minerals (calcite, dolomite, feldspar, clay and quartz) as determined by X-ray diffration. This study revealed the presence of As, Sb and Br as pollutant microelements.     

Methods and concerns in disposal of nuclear waste from storage vials post recovery

Journal of Radioanalytical and Nuclear Chemistry - The speciation of iodine in environment must be known in order to properly assess its geological fate and to study potential remediation materials...     

Amazon estuary — assessment of trace elements in seabed sediments

The interactive processes operating on the continental shelf adjacent to the river mouth control the amount and the characteristics of the Amazon discharge reaching the Atlantic Ocean. In this study, the distribution of trace elemental concentrations, with emphasis to the rare-earth elements, in sediment cores collected at several stations from the Amazon continental shelf during the falling water period was investigated by instrumental neutron activation analysis. Cores from the terrigenous and blue water zones have relatively uniform REE concentrations throughout the profile. Cerium anomalies for samples of the upper section of the eight stations are consistently positive and of high values (normally >2). Similar variation in the elemental concentration ratios between the seabed sediments and Amazon River suspended sediments was seen for stations located in the biogenic and blue water zones, with an enrichment for Ce, Sm, Fe, Th, and Sc and a depletion for the La, Eu, Tb, Yb, Co, Cr, Cs, Hf, Ta, and Zn. The shale-normalized REE patterns from shelf sediments are enriched in LREE relative to HREE, with enrichment factors varying from 1.5 for stations near the river mouth (terrigenous zone) to 1.9 for stations located far in the blue water zone. Published data for the Amazon River suspended sediment agree remarkably well with this observation of LREE-enrichment.     

Geochemical investigation of alluvial sediments: validation of ICP-OES determination of heavy metals. A case study from the Utrata River Valley (central Poland)

The development and validation of a reliable analytical procedure for the determination of selected metals (Cd, Cr, Cu, Pb, Zn and Mn) in sediments accumulated in the Utrata River (Poland) is described. The aqua regia extraction followed by inductively coupled plasma optical emission spectrometry (ICP-OES) was used for this purpose. The optimized analytical procedure was validated, and adequate quality control actions were implemented in order to provide reliable data. The precision under’ within-laboratory’ reproducibility conditions was estimated from duplicate analysis. Certified reference material (CRM) was used in order to evaluate the accuracy of the results regarding the sewage sludge amended soil CRM 143R. The detection limits for all elements of interest were well-below their content in the investigated sediment samples. The obtained reliable data could be used for assessment of the relationship between human economic activity in the past and the geochemical features of the sediments.