土壤重金属生物有效性的评价方法

土壤重金属污染已成为人们广泛关注的全球性的环境问题之一。重金属生物有效性已成为污染生态学研究的前沿。对国内外土壤重金属生物有效性评价方法的研究进展作了简要综述，并对今后的研究作了展望。     

重金属有效态与土壤环境质量标准制订

制订合适的土壤环境质量标准是评价土壤健康质量及食品安全的核心问题,而土壤重金属有效态对制定土壤环境质量标准具有重要意义。土壤重金属有效态主要指植物有效态,它与重金属形态关系密切。影响土壤重金属有效态的因素很多,主要包括:土壤pH值、氧化还原电位、CEC、有机质含量、粒径组成(黏粒含量)、铁铝锰氧化物含量、植物种类、土壤微生物、土壤温度的高低、重金属来源等。化学试剂浸提法是测量重金属生物有效性的常用方法,所用化学试剂主要有三类:弱(稀)酸、络合剂和中性盐,中性盐由于对土壤pH值影响小而受到重视。我国现行土壤质量标准采用土壤重金属总量和pH两个因素为依据,但是不少学者认为,该标准仅适用于重金属有效态较高的土壤,而不能反映重金属有效态含量较低土壤的实际状况。     

化学钝化法修复重金属污染土壤研究进展

化学钝化修复是通过往土壤中加入钝化剂,以调节和改变重金属在土壤中的物理化学性质,使其发生氧化还原、沉淀、吸附、螯合、抑制或拮抗等一系列反应,降低其在土壤环境中的生物有效性和可迁移性,从而减少这些重金属元素对动植物的毒性.这种方法因投入低、效率高、修复快速、操作简单等优点,对大面积污染土壤的修复具有较好的应用前景.文中系统地综述了土壤重金属污染现状、危害、来源、特点及化学钝化修复技术的类型、作用机理、影响因素、修复实例,并分析了化学钝化技术的研究现状、存在的问题及未来的发展方向.     

土壤环境生态对重金属元素迁移影响分析

作物中重金属元素主要来自土壤，其含量与作物种类和土壤环境有关。土壤中重金属元素含量、土壤pH值、Eh值、土壤化学组成、土壤质地等环境因素都影响作物中重金属元素含量。土壤pH值和Eh值影响重金属元素的活动性。重金属元素的水溶态容易被作物吸收，而难溶态和被土壤胶体固定的重金属元素，不能被作物吸收。同种作物重金属元素含量的差异主要取决于土壤环境。     

土壤重金属生物地理地带性分异研究获进展

<正>中科院地理资源所研究人员在土壤重金属生物可给性地理地带性分异领域取得重要进展,相关成果发表于《环境科学与污染研究》。生物可给性一般指污染物在生物传输或生物反应中被利用的程度。重金属元素的生态与健康毒性在很大程度上取决于其生物可给性含量而非总量,因此以重金属可给性含     

冲积平原区土壤中重金属元素的存在形态分析

采用0.1mol／L氢氧化钠浸提腐殖酸的方法,将土壤中的腐殖酸及与腐殖酸结合的重金属元素分离出来;分别用分光光度法、原子荧光光谱法、等离子质谱法测定样品中腐殖酸及重金属元素的含量;初步测定结果显示：与腐殖酸结合的重金属元素是冲积平原区表层土壤中重金属元素的1种重要存在形态,而且可能是土壤中重金属污染元素主要的存在形式。     

浅谈重金属元素在土壤中的迁移及黏土矿物对其修复作用

重金属元素在土壤中的存在形式有多种,且迁移能力各不相同,而影响重金属元素形态的因素是土壤p H、土壤植物根际环境,重金属元素迁移的过程还受到土壤类型、含水量以及土壤中有机和无机配体的影响。黏土矿物具有良好的吸附作用,它主要是通过离子交换、配合反应和共沉淀反应来修复土壤中的重金属污染。     

涡旋提取-石墨炉原子吸收光谱法测定土壤中有效态镉

土壤作为农业生产的重要载体,是保障农产品质量安全的关键源头。近年来,随着经济的快速发展,土壤中重金属污染问题日益凸显,已成为世界性的重大环境问题之一。目前针对土壤中重金属的调查分析大多处于总量水平,这并不能全面地评价重金属的生态风险,因为土壤-重金属-生物体之间存在复杂的动态相互作用,土壤中只有部分重金属能被生物体吸收,这部分能被生物体吸收利用的元素以特定的形态存在,这种特定的形态被称之为有效态。土壤中重金属能否被植物吸收主要取决于该元素的有效态[1],因此土壤中重金属有效态含量的测定,对评价和控制其生物毒害作用具有更实际的意义。镉是生物蓄积性强、具有"三致"作用的剧毒元素,会通过食物链富集到人体,从而对人体健康造成危害[2]。目前我国暂未制定土壤中有效态镉的限量标准,关于土壤中有效态镉含量测定方法的研究也较少[3-5],国家标准方法 GB/T 23739-2009(S)《土壤质量有效态铅和镉的测定原子吸收法》前处理采用振荡器低效提取,提取时间长,试剂用量大,提取液根据含量高低选用火焰原子吸收光谱仪或者石墨炉原子吸收光谱仪,操作较繁琐,无法满足批量样品快速分析的要求。文献[3-4]采用超声提取-电感耦合等离子体质谱法,前处理操作简单,但仪器成本较高,方法应用的推广有一定的局限性,且由于土壤样品基体复杂,容易堵塞雾化器导致仪器故障。     

定南县废弃稀土矿区土壤中重金属元素Pb、Cr和Cu的测定

为了解废弃稀土矿土壤及周边土壤的重金属污染及对环境的影响,采用HNO3-HClO4湿法消解土壤样品,用原子吸收分光光度计及标准曲线法对消解样品中的重金属元素Pb、Cr、Cu含量进行了测定。根据国家土壤环境标准评价这3种重金属元素在该土壤中是否超标及超标程度。结果表明,赣州市定南县废弃稀土矿区及周边土壤中铅含量严重超标;矿区及周边土壤Cr含量未见超标;周边土壤铜含量接近超标。可见该废弃稀土矿区重金属元素污染以Pb为主,建议在土壤植物修复过程中着重考虑对Pb元素的清除。     

方波阳极溶出伏安法同时测定水样中微量的铅和镉

重金属元素在水和土壤中很难降解且具有富集性,往往长期积累在生物体内,直接影响人类生存环境、危机人类健康.其中,铅和镉是生态环境中最常见和最主要的污染元素.     

Spectrophotometric determination of traces of several metals in ferrous and nonferrous metals and alloys after isolation by iodide extraction

Methods are presented for the determination of traces of lead, cadmium, indium, bismuth, copper, and antimony in most of the important metals and alloys used in industry. The trace metals are isolated by hexone extraction of their iodides from 5% hydrochloric acid solution and then determined spectrophotometrically. The attractive feature of the proposed procedures is that the method used for each of the trace metals is applicable to all of the matrix metals and alloys being considered.     

Trace Metal Speciation and Research in Marine Geochemistry

Abstract

In order to precise the origin and behaviour of trace metals associated with coastal marine sediments, marine geochemists frequently utilize various methods of sequential extraction. The main objective is to test the potential mobility / stability of particulate metals in the natural environments. Several examples are presented in the article, namely: i/ Exchangeable Pb from podzolic soils of the drainage basin of a lagoon which sediments and phreatic waters are for a large part inherited from the surrounding soils; ii/ Evolution of particulate metals in an estuary; iii/ Mobility of metals at the sea bottom interface; iv/ Role of amorphous components of estuarine sediments and suspended matter; v/ Effects of dredging activities on solubility of metals in an estuary; vi/ Behaviour of heavy metals in lagoons.

Main results obtained from the extraction procedures are described, as well as particular difficulties encountered when applying some classical methods.     

Grundzüge der Deformationsprozesse in Metallen

The physical principles of our present understanding of the elastic, the anelastic, and the plastic deformation of metals are discussed. The following specific cases are considered in details.

1. Elastic deformation due to one of the following processes. Energy elasticity, vibrational entropy elasticity, anomalies in the elastic behaviour resulting from lattice instability or ferromagnetism. This behaviour is compared with the entropy and energy elasticity of polymers.
2. Anelastic deformation due to one of the following mechanisms. Difussion of solute atoms and/or point defects, dislocation relaxation, dislocation resonance interaction between dislocations and other lattice defects, migration of grain boundaries, phase boundaries or domain walls.
3. Plastic deformation of pure metals by cooperative shear, dislocation motion, mechanical twinning, martensitic transformations and by diffusion. The effect of alloying on these processes is discussed in the case of solid solutions, ordered alloys and precipitation hardened materials. The dominant deformation modes of polymers are different from those of metals because metals are formed by atoms with relatively isotropic interatomic forces, whereas polymers generally consist of long chains characterized by a strong anisotropy in chemical bonding. This difference makes the deformation stress of polymers and metals depend differently on temperature, pressure, and deformation rate. An other characteristic difference between the deformation of polymers and metals is that metals deform plastically, whereas a large fraction of the so-called plastic deformation of polymers is really anelastic.

     

西南山地煤矿区耕地土壤-农作物重金属富集及健康风险评价

为了解西南某典型山地煤矿区周边农田土壤、农作物重金属的富集情况及对当地人群健康的影响程度,采集矿区周边农田土壤样品和对应的农作物样品,测定重金属Cr、Mn、Zn、As、Pb的含量。运用Nemero指数法、潜在风险指数法对土壤重金属的污染程度进行评价;采用靶标危害系数法(THQ)评价农作物重金属对人体的健康风险。结果显示,Cr、Mn、Zn、As、Pb分别是背景值的1.81、1.90、2.89、1.30、0.86倍,处于轻度污染级别,轻微危害程度。农作物重金属Cr、Pb和As含量的超标情况较严重,Zn的含量超标相对较小。各农作物富集的重金属对人体的健康风险大小为：高粱>玉米>白菜>葱>辣椒。农作物重金属对儿童健康的危害均达到了慢性中毒;对成人健康的影响,高粱处于慢性中毒,其它农作物重金属处于产生较大影响的危害程度。农作物重金属与土壤重金属的相关性分析表明,农作物重金属的含量与土壤重金属全量并无线性关系;各重金属在农作物中的转移能力不同;Pb,As在农作物中的转移能力较大,而Cr相对较小。鉴于矿区重金属的富集情况,应尽快采取修复治理措施,为保证当地人群健康,建议当地居民不再食用和种植富集重金属严重的高粱、玉米农作物。     

新墙河区草本植物重金属含量的测定

用HNO3∶HClO4=4∶1(V/V)混酸消解草本植物后,采用原子吸收光谱(AAS)法测定样品中铅、砷、镉、铜、锌。结果表明:方法加标回收率94.7%~100.3%,相对标准偏差0.8%~8.7%。草本植物各不同部分重金属含量有所不同;新墙河流域草本植物重金属含量相对偏高,新墙河的一条支流油港河比另一条支流沙港河重金属污染严重,是新墙河的主要污染来源。该法用于草本植物重金属含量的测定快速、灵敏、重现性好。     

Occurrence of Selected Metals in Wastewater Effluent and Surface Water in Ireland

Metals occur naturally in the environment and as constituents of the Earth’s crust. They have many uses, and metals such as iron, copper, and zinc are widely used in industries. Elevated levels of metals in the environment also occur as a result of human activities (municipal, residential, and traffic–related activities). A list of 15 metals chosen for this study included priority substances and those listed in the European Union Water Framework Directive 2000/60/EC. The concentrations of heavy metals in the environment are affected by several factors that must be taken into account when monitoring heavy metals released into the environment through wastewater treatment plants (WWPTs). This work examines the concentrations of metals found in WWPTs and the effects of treatment type on dissolved metal concentrations. Effluent samples were collected from the outflow of nine WWPTs in Dublin and Cork, Ireland from July 2009 to June 2011. All samples were found to contain priority metals that exceeded environmental quality standards in several cases. We present the frequency of occurrence and concentrations of metals in effluents of studied WWPTs and discuss relationships between the occurrence of heavy metals, the influence of factors such as industrial inputs, levels of treatment at WWPTs, and percentage urban area in an agglomeration. The results of this study are an indication that WWPTs may be contributing to the high levels of heavy metals found at discharge points back into river systems.     

Validation of the methods for heavy metal speciation in soils and sediments

The knowledge of the chemical forms of metals is used to assess their availability and uptake by plants, and in sediments the forms of metals determine their transport and mobility in the aquatic media. This information may be obtained by determining chemical forms of metals (speciation) or different phases in which the metals are bound, obtained by applying extraction schemes. The analytical methods used include different steps and all of them must be validated. We report here the recommendations to minimize the errors in this kind of analysis. For validation the use of Certified Reference Materials (CRMs) and the participation in interlaboratory exercises are highly recommended.     

Determination of trace metal complexes by natural organic and inorganic ligands in coastal seawater.

It is well-documented that organic compounds form strong complexes with most metals in aquatic systems, and that seawater is a complex medium which contains a large variety of organic and inorganic ligands, including colloidal matter. We suggest that most trace metals are complexed in seawater and that some inorganic metals complexes are either labile or not stable. In contrast, metal-organic complexes are often stable and need various and specific treatments to be dissociated. In this paper we try to illustrate a good tendency of some trace metals to be complexed by organic ligands in seawater. A solid-phase extraction method was applied using a C18 column as a resin that is able to separate metals complexed by neutral organic ligands, and the chelamine resin to separate metal species that are present as labile inorganic complexes. The determination of total dissolved metal concentrations was achieved by formatting a metal-8-hydroxyquinoline complex, followed by adsorption on C18 columns and ICP-AES analysis.     

Diantipyrilmethane as complex-forming reagents in the thin-layer chromatographic determination of metals

Summary The efficiency of diantipyrilmethane used as a reagent for the chromatographic separation of metals, including titanium, zirconium and hafnium, rare earth elements, transition and platinum metals is shown. The peculiarities of the chromatographic behaviour of metal diantipyrilmethanates and the mechanism of their retention in TLC are discussed. Methods were developed for the determination of metals based on complex formation directly in the sorbent layer or by liquid extraction. The chromatographic separation takes place in silica gel thin layers with elution by organic solvent-mineral acid mixtures. The metals are determined by densitometric or spectrophotometric methods. After the complexes are isolated from the layer. The procedures are characterized by simplicity, efficiency, and a rather high selectivity. They were used to analyze steels, alloys, industrial solutions and other samples.     

准东煤中碱金属的赋存形式及其在燃烧过程中的迁移规律实验研究

对新疆煤采用三步化学提取实验(蒸馏水洗、醋酸铵洗、稀盐酸洗)以分析其碱金属赋存特性,对水溶的阴离子进行了离子色谱分析。分别检测了在不同温度、不同停留时间下准东煤灰的碱金属量,并用Factsage软件模拟该煤灰中碱金属的析出形式。结果表明,煤中的钠主要是水溶钠,钾主要以不可溶钾存在,水溶碱金属主要以水合离子形式的氯化物存在。准东煤中碱金属在400~600℃析出最快,主要是水溶态碱金属的释放,碱金属的释放主要发生在燃烧后期。灰中碱金属在高温下会与烟气中的成分发生反应,主要产物是氯化物以及氢氧化物。在700℃钠对准东煤中低温共融物的形成有很大贡献。