海水中痕量铂族元素的赋存形态及螯合树脂富集研究进展

海水中铂族元素(PGEs)的含量和赋存形态与其生物地球化学行为及生态风险密切相关,但如何确定海水中PGEs的含量和形态一直是研究的难点.螯合树脂对特定元素和特定配体结构的识别特性为突破这一瓶颈提供了可能.因此,本文综述了海水中铂族元素赋存形态的研究现状,讨论了螯合树脂吸附铂族元素的机理,并对比了不同类型螯合树脂对铂族元素的富集.结果表明: 海水中PGEs的无机络合形态主要由[MCl₃OH^2-]/[MCl4^2-](M=Pt、Pd)及M(OH)₃^{3-n(n=3～6)(M=Rh)组成;螯合树脂对PGEs的不同络合形态有一定的识别性;氮-硫型螯合树脂是研究实际条件下海水中PGEs的理想树脂.}     

环境中人为来源的铂族元素及其迁移转化研究进展

铂族元素(PGEs)在汽车尾气催化转换器(VECs)、工业催化剂和制药学领域的广泛应用,致使PGEs尤其是铂(Pt)、钯(Pd)和铑(Rh)在某些区域已经成为新型环境污染物.由于环境样品中Pt/Pd、Pt/Rh与VECs中活性成分比例有较好的相关性,因此PGEs污染主要来源于应用了铂族金属的VECs.研究显示,过去的30年里,气溶胶、永生态系统(河水、雨水、地下水、海水、沉积物)、土壤、路尘和生物有机体等不同环境介质中PGEs浓度均显著增加.人们普遍认为铂族元素是惰性的,暴露于环境中的PGEs的健康风险很小,但PGEs毒性和生物可利用性的研究表明,在多种生物地球化学过程作用下,人为排放的PGEs易发生迁移,转化为毒性更大的形态,增加生物可利用性,通过食物链传递对人类产生潜在的健康风险.本文对不同环境介质中PGEs来源、分布及生物地球化学行为的最新成果进行了总结,认为PGEs人体健康风险标准制定、PGEs标准物质的研制、近海沉积物中PGEs的研究、PGEs对滩涂贝类的毒性、食物中PGEs的污染现状及人体健康风险评估等是今后PGEs研究的重要领域.     

黑曲霉发酵过程中菌体形态的分析方法建立及应用

丝状真菌(Filamentous fungi)的发酵生产通常具有较高的工业应用价值,但其菌体形态是一个区别于其他非丝状菌的一个重要发酵指标。针对目前形态分析的瓶颈,本研究使用琼脂糖凝胶对黑曲霉菌形进行固定,利用平板实现菌球样本的大量制备,并结合图形处理软件自建自动化处理程序,实现了大量准确可靠的菌体形态参数的获得,大大增加了形态数据处理通量及准确度。应用该方法于黑曲霉发酵生产糖化酶过程中不同供氧水平及剪切水平下菌体形态的研究,通过大量形态数据定量阐明了黑曲霉在不同剪切水平下的分区域形态分布特性,为进一步工业过程的形态优化提供了重要的研究方法。     

发光细菌法测定环境中金属毒性的研究进展

在环境污染物的毒性评价和监测中,发光细菌法是一种具有快速、灵敏和廉价等优点的直接生物测试方法.本文简要回顾了发光细菌法的测定原理及其在水环境中的应用;总结了发光细菌法测定水环境中金属毒性的主要影响因素(如pH、有机无机配体和交互作用);重点评述了发光细菌法在土壤样品金属毒性测定方面的应用、不同提取方法的优缺点以及土壤金属毒性与形态之间的关系;提出今后应加强土壤中金属对发光细菌的毒害机理、土壤环境中发光细菌法标准化以及发光细菌法与其他测试方法的关系等研究.快速、廉价、标准化发光细菌法的建立对土壤环境中金属风险评价和监测具有重要的意义.     

环境与植物中硒形态研究进展

本文综述了近年来在环境及植物中的硒形态研究方面的进展。在土壤和水中各种不同形态硒的分布情况与pH值及其它特性之间的关系;植物中各种有机硒化合物的含量,可能的结构和硫素之间的关系,植物对硒的吸收转化过程等等。     

环境与植物中硒形态研究进展

本文综述了近年来在环境及植物中的硒形态研究方面的进展。在土壤和水中各种不同形态硒的分布情况与ｐＨ值及其它特性之间的关系;植物中各种有机硒化合物的含量,可能的结构和硫素之间的关系,植物对硒的吸收转化过程等等     

水体中铝（Ⅲ）的化学形态及其生态效应的研究进展

本文着重论述了水体中各种铝络合物的形成结构、分布特征和转化规律,分析了当前广泛使用的几类定量鉴别方法,阐明某些形态的铝对生物体及人类的毒性作用和生理功能性障碍等生态效应方面的研究进展。同时提出未来研究的重点领域和方法。     

菌根植物根际环境对污染土壤中Cu、Zn、Pb、Cd形态的影响

采用根垫法和连续形态分析技术,分析了生长在污灌土壤中菌根小麦和无菌根小麦根际Ｃｕ、Ｚｎ、Ｐｂ、Ｃｄ的形态分布和变化趋势。结果表明,下对照土壤相比,菌根际土壤中交换态Ｃｕ含量显著增加,交换态Ｃｄ呈减少的趋势;与非菌根际相比,Ｃｕ、Ｚｎ、Ｐｂ的有机结合态在菌根根际中显著增加,而４种测定金属２的碳酸盐态和铁锰氧化态都没有显著改变,该结果表明,植物根系能影响根际中金属形态的变化,且菌根比无菌根的影响程度大     

积雪草活性成分的分析方法及药理作用研究进展

就近年来国内外对积雪草的化学成分、提取纯化、分析检测方法和药理活性的研究进展作了综述,为积雪草的进一步开发利用提供科学依据。     

农作物体内铅,镉,铜的化学形态研究

本文报道了农作物体内重金属存在的化学形态。用逐步提取法分析了生长在污染土壤上的水稻、小麦的根与叶。结果表明,在两种作物中,根部的铅以活性较低的醋酸可提取态与盐酸可提取态占优势,而叶中的铅以盐酸可提取态占优势。不论根部或叶部,在各种形态镉中,以氯化钠可提取镉所占比例较高,作用较重要。作物体内的铜活性较强,根部以乙醇可提取态占优势,叶中以水提取态占优势。各种结合形态的重金属迁移能力、毒性效应有显著差异。作物体内重金属化学形态特征与其表观毒性效应有密切联系。     

Distribution patterns of Cd,Cu, Mn,Pb and Zn in wood fly ash emitted from domestic boilers

Abstract

Wood fuels being a renewable source of primary energy have been considered environmentally friendly. However, wood combustion in domestic boilers is a source of air pollution. The lack of a dust collection device is the reason why flue gases emit a significant load of particulate pollutants into the air, including heavy metals. The aim of this research was to assess the environmental hazard caused by both emissions of heavy metals during wood combustion in domestic boilers and their chemical forms present in fly ash.

From the various wood fuels burnt in domestic boilers, the fly ash selected for this study came from the combustion of briquettes of softwood from non-polluted areas, and from burning hardwood fuel from trees exposed to pollutants from heavy traffic. The wood fuels satisfy the quality demands determined in the EN 14961 Solid Biofuels - Fuel quality assurances. However, the concentrations of Cd, Cu, Pb and Zn in the fly ash are considerably higher than the appropriate limit values determined for soil improvers. Sequential extraction shows that Cd and Zn are associated mainly with the water leaching and carbonate fractions, regarded as mobile and bioavailable, and pose the potentially greatest hazard to the environment and human health. Cu, Mn and Pb associated with less mobile fractions may not pose a direct air quality hazard but, due to their high concentrations, medium-term and long-term effects on soils and surface and subsurface waters should be considered.     

Synthesis and spectral luminescent characteristics of the porphyrin complexes with the platinum group metals

The syntheses of complexes of natural and synthetic porphyrins with Pt, Pd, Rh, and Ru are reported. Their electronic absorption spectra, phosphorescence spectra, and lifetimes at room temperature both in the presence and in the absence of oxygen were studied. Variations in the nature of the central metal atom and in the substituents in pyrrol and phenyl rings allow the obtaining of metalloporphyrins phosphorescing at room temperature with various phosphorescence excitation and emission spectra.     

Sludge-Derived Cu and Zn in a Humic-Gley Soil: Effect of Dissolved Metal-Organic Matter Complexes on Sorption and Partitioning

A sequential extraction scheme was combined with sorption isotherm analysis in order to investigate sorption of sewage sludge-derived Cu and Zn to the A-horizon of a humic-gley soil as a whole, and to the operationally defined exchangeable (1?M MgCl₂), carbonate (1?M NaOAc), Fe/Mn oxide (0.04?M NH₂OH.HCl), and organic (0.02?M HNO₃+30% H₂O₂) soil fractions. Sorption parameters were compared for a sample of sludge leachate (with 97.4% of Cu and 63.2% of Zn present as dissolved metal-organic matter complexes, as calculated by geochemical modeling involving MINTEQA2 and verified using an ion exchange resin method) with that of a reference solution exhibiting the same chemical characteristics as the leachate, except for the presence of dissolved organic material. Dissolved metal-organic matter complexes were found to significantly (P<0.05) depress sorption to the bulk soil and each fraction. The greatest depression of Cu and Zn sorption was observed for the exchangeable, carbonate, and Fe/Mn oxide fractions, while the organic fraction of the soil was the least affected. This reflects a greater affinity for the exchangeable, carbonate, and Fe/Mn oxide fractions by the free divalent metal (Cu²⁺, Zn²⁺), with sorption by these fractions attributed to cation exchange, chemisorption, and co-precipitation processes. The sorption characteristics of the organic fraction indicated that Cu and Zn sorption by soil organic matter mostly involved dissolved metal-organic matter complexes. This may be attributed to hydrophobic interactions between nonpolar regions of the dissolved metal-organic matter complexes and solid-phase soil organic matter.     

Chemical Extraction of Arsenic from Contaminated Soils in the Vicinity of Abandoned Mines and a Smelting Plant Under Subcritical Conditions

Under subcritical conditions, we studied the chemical extraction of arsenic (As) from contaminated soils that were sampled from the vicinity of abandoned mines and a smelting plant in South Korea. The total initial concentrations of As in the soil samples from the Myungbong and Cheongyang mines and the Janghang smelting plant were 298.6, 145.6, and 103.7 mg/kg, respectively. X-ray photoelectron spectroscopy analysis showed that the species of As identified in the soil was As(+V), including As₂O₅ and AsO₄ ^3? _. At 20°C, only 27.4, 26.5, and 40.1% of the total As was extracted from the Myungbong, Cheongyang, and Janghang soil samples, respectively, with 100 mM of NaOH. As the temperature was increased to 300°C, the extraction efficiencies remarkably increased. However, to achieve the complete extraction of As from the soils, 100 mM of citric acid, EDTA, or NaOH was needed at 200, 250, or 300°C. Extraction with subcritical water at 300°C resulted in incomplete extraction of As from the soils. The results of these experiments indicate that extraction mechanisms other than oxidative dissolution of As(+III) species may be responsible for the enhancement of As extraction. Our results suggest that subcritical water extraction combined with extracting reagents can effectively remediate As-contaminated soil regardless of the As species.     

Effects of storage on the sequential extraction of micronutrients and trace elements in fruit and vegetable residue flour

Abstract

Sequential extraction consists of the use of a number of extractors with different chemical properties that are progressively applied to a sample. The objective of this study was to evaluate the influence of sequential extraction of Cu, Fe, Mn, Mg and Zn from fruit and vegetable residue flour during storage for up to 60 days. The following extractors were applied: 1M calcium chloride, 0.1M acetic acid/5% ammonium acetate (pH 5.0), 0.5M acetic acid and 0.5M hydrochloric acid; the storage times were 0, 30 and 60 days. Storage for up to 60 days did not affect the total content of the metals. However, changes were observed in the chemical structure of the sample, which influenced the profile extraction of the metals. At least five distinct chemical species of each metal were analysed, which could influence the bioavailability and metabolic processes inherent in the sample itself.     

Cumulative Title Index

Abstract

Metal fractionation is a powerful tool for studying the mobility, bioavailability and toxicity of metals in sediments and soils. A seven-step sequential extraction technique was used to determine the potential mobility of selected heavy metals (Fe, Mn, Zn, Cu, Pb, Cd and Ni) in the sediments of Lake Naivasha. Results indicate that residual fraction was the most important phase for the elements Fe, Mn, Cu and Zn. However, Pb and Cd are highly enriched in the non-residual phases. Nickel on the other hand was distributed evenly between the non-residual and the residual fractions.

The total concentrations of the heavy metals suggested a decreasing order of iron ?> manganese ? zinc > nickel > copper ? lead > cadmium. However, the detailed sequential extraction data indicated an order of release or mobility of cadmium > lead ? nickel ? zinc > manganese > copper > iron. The high percentage of Cd and Pb in the mobile fractions suggests high bioavailability of these two elements in the study area and maybe a pointer to anthropogenic input of the two elements in the study area.     

A Site-Specific Approach for the Evaluation of Natural Attenuation at Metals-Impacted Sites

Consideration of monitored natural attenuation (MNA) as a remedy component for metals-contaminated sites can be achieved using a site-specific screening approach, followed by application of one or a series of sequential extraction measurements. Hazardous waste sites contaminated with metals can be screened for the implementation of monitored natural attenuation on the basis of contaminant-specific soil chemical characteristics (i.e., K_d's, solubilities, and nonexchangeable sorbed fraction). Field cases are used to demonstrate the screening approach and to outline the primary considerations involved in accurately applying sequential extraction procedures to support the of MNA for site remediation. The results of these case studies provide strong evidence that site-specific screening and the use of sequential extraction procedures are effective methods for evaluating natural attenuation for metals impacted sites.     

Time evolution of Pb(II) speciation in Pampa soil fractions

Abstract

Soil pollution by heavy metals, particularly lead, is an important environmental concern; the bioavailability of such pollutants is strongly dependent on their chemical form. Here, the speciation of Pb(II) in soil fractions as a function of time shortly after its incorporation is studied, using a selective sequential extraction method. The sample came from an Argentinean Pampas region and was extensively characterised, including Rietveld analysis of the silt+clay fraction XRD pattern to find the major mineral components. Experiments were run twice, once in the winter and once in the summer. The results show different speciation time profiles in both cases, showing faster changes in winter due to the higher water content. The summer experiment corresponds to an earlier stage in the speciation profile evolution compared with winter. The soluble/exchangeable fraction decreases with time in summer but shows a lower and constant value in the winter. A high proportion is found to be adsorbed onto the stable (aluminosilicates+quartz) mineral fraction. The results strongly suggest that, even at a short time following soil pollution with Pb, a high proportion is adsorbed onto the mineral fraction, with only a low fraction being bioavailable. The most stable (mineral incorporated) form is observed to increase with time. Soil water content appears to be more important than temperature in determining the differences between the two.