沉积物样品中痕量元素汞的形态分析研究进展

归纳总结了沉积物中汞形态分析研究进展,内容包括沉积物汞的赋存形态,样品的预处理和不同形态汞的原子光谱法、色谱法、电感耦合等离子体质谱法及联用技术等分析方法,指出了存在的问题和未来的发展方向。     

煤中汞赋存形态及其热解时析出规律研究

利用程序升温热解反应系统,研究了煤中不同形态汞的析出温度,通过积分各析出温度下汞的总析出量来分析各赋存形态的汞所占比例,同时研究了添加CaCl2后抑制煤热解过程中汞析出的机理。结果表明,实验所选煤中汞主要存在三种赋存形态,其析出温度点分别在220、300和400℃;其中,300℃析出的汞所占比例最高,为54.18%,从析出温度分析该部分汞主要以HgS的形式赋存。添加CaCl2对第一和第三赋存形态的汞析出具有抑制作用,改变了其析出温度,对第二赋存形态的汞析出几乎无影响,添加后使得汞析出温度更为集中;抑制析出的主要原因是氧化吸附,添加CaCl2对汞总析出量基本无影响。     

煤中汞赋存形态及其热解时析出规律研究

利用程序升温热解反应系统,研究了煤中不同形态汞的析出温度,通过积分各析出温度下汞的总析出量来分析各赋存形态的汞所占比例,同时研究了添加CaCl₂后抑制煤热解过程中汞析出的机理。结果表明,实验所选煤中汞主要存在三种赋存形态,其析出温度点分别在220、300和400 ℃;其中,300 ℃析出的汞所占比例最高,为54.18%,从析出温度分析该部分汞主要以HgS的形式赋存。添加CaCl₂对第一和第三赋存形态的汞析出具有抑制作用,改变了其析出温度,对第二赋存形态的汞析出几乎无影响,添加后使得汞析出温度更为集中;抑制析出的主要原因是氧化吸附,添加CaCl₂对汞总析出量基本无影响。     

大气中活性气态汞的分析方法和赋存转化

活性气态汞(Reactive gaseous mercury, RGM),在大气环境中通常被认为是气态的氧化汞,主导大气汞沉降过程,对汞的全球循环至关重要。本文详细介绍了RGM的多种采样和分析方法,讨论并比较了当前技术的优势和局限性;对RGM在大气中的生成、赋存、清除等环境过程以及相关的机制进行了梳理,并探究各过程在大气汞循环过程中的贡献。针对当前RGM分析的难点(如赋存浓度低、采集困难)与关键科学问题(如赋存形态与转化),需着力发展实际环境中RGM采集和形态分析的可行方法,进而深入探究其环境行为。大气中RGM的分析方法和环境行为研究是极具挑战性的任务,将是未来大气汞研究的重要内容之一,对于深入理解RGM在大气汞循环过程中的作用具有重要的意义。     

土壤和沉积物中汞形态分析的研究

本文根据各种形态汞氧化还原和溶解性质的差别建立了土壤和沉积物中汞形态分析的系统方法.研究了测定各形态汞的实验条件,考察了各形态汞相互间的干扰情况,并对一些实际样品进行了系统分析.结果表明,所建立的方法可用于土壤和沉积物中汞赋存形态的研究.     

晋城煤中汞的热稳定性与赋存形态的研究

利用程序升温热解反应器─元素汞在线检测系统联用装置,研究了晋城煤中汞的热稳定性以及与热稳定性相关的晋城煤中汞的赋存形态。研究表明,煤中大部分汞与煤中无机矿物质伴/共生,少部分与煤中有机质伴/共生。其中,在200℃~300℃和900℃~1200℃释放的汞与煤中无机矿物质伴/共生,在300℃~600℃释放的汞部分与无机矿物质伴/共生,部分与煤中有机质伴/共生。     

土壤中汞赋存形态及迁移转化规律研究进展

对汞污染的来源、危害、在土壤中的赋存形态、迁移转化规律及其影响因素进行了综述,在此基础上简要介绍了土壤汞污染的治理,提出了存在的问题和有待进一步研究的方向。     

环境样品中痕量锑的形态分析研究进展

总结了近年来环境样品中痕量锑的测定方法研究进展,内容包括水环境体系中锑的赋存形态、传统的样品预处理和分离富集技术、现代仪器在线分离分析技术,并指出了痕量元素锑形态分析存在的问题和未来的发展方向。     

洗选过程对宁武煤中汞迁移和热释放的影响特性

采用逐级化学提取和热分析方法,选取宁武煤田某洗煤厂原煤及洗选产物为研究对象,在汞质量平衡基础上对煤中汞赋存形态进行分类并验证,进而考察了洗选过程对煤中汞迁移行为和热释放的影响特性。结果表明,洗选过程在降低原煤灰分和硫分含量的同时也改变了汞的富集规律,引起了汞的重新分配;样品中汞元素与灰分和硫含量之间的线性相关性分别为0.89和0.99,原煤中汞主要以无机结合态存在,其迁移行为受控于无机矿物质迁移,洗选后矸石总汞绝对含量较原煤增加了322.8%,而精煤汞含量降低至原煤的40%,汞脱除率达到56.4%;洗煤产物中汞富集程度的差异与其在原煤中赋存形态密切相关,其中,矸石中硫化物结合态汞的占比高达56.6%,而精煤和煤泥中有机结合态汞较原煤中均有所提高;相同温度下汞在煤泥中释放率最大,矸石中最小,所有样品中汞至650℃均接近完全析出;煤中汞热释放特性也与其赋存形态密切相关,不同热解温度段汞热释放行为由煤中汞的固有赋存形态所决定,其中,有机结合态汞随有机质分解在300℃已大量逸出,而硫化物结合态汞分解温度主要为400-600℃。     

天然水体中痕量汞的形态分析方法研究

天然水体中汞的含量仅为ng/L级，不仅难以测出，而且在测定过程中极易受到干扰；利用两次金汞齐的预富集方法与原子荧光法结合的技术，作者建立了天然水体超痕量不同形态汞的准确分析方法；该方法的检出限达到了0．02ng／L，实验平均回收率为101%；该方法也适用于其它低汞含量水样(包括稀释后的污水及化工废水)中汞的形态分析。     

Application of a Carbon Paste Electrode Modified with a Schiff Base Ligand to Mercury Speciation in Water

A carbon paste electrode, modified with benzylbisthiosemicarbazone is used for mercury speciation in water samples. Mercury ion is selectively accumulated on the electrode surface at open circuit and its analysis was performed by cyclic voltammetry or square‐wave voltammetry (SWV). A detection limit of 8 μg L^?1 (3σ) was found for 15 min of accumulation using SWV as measurement technique. The effect of several metallic ions and organic substances on voltammetric signal is examined. For speciation purposes, a ligand competition methodology between ligands in solution and electrode is used. Model mercury complexes are characterized as a function of their dissociation kinetics. The method was applied to mercury speciation in water samples from the Jarama River in Madrid.     

Sample treatment selection for routine mercury speciation in seafood by gas chromatography–atomic fluorescence spectroscopy

A general analytical strategy for mercury speciation in seafood samples has been proposed to increase sample throughput. This consists of the initial determination of total mercury content, and then mercury speciation using gas chromatography coupled to atomic fluorescence spectroscopy. The appropriate sample treatment for mercury speciation is selected between a method based on aqueous ethylation with sodium tetraethylborate (Approach A: a rapid methodology for samples with methylmercury concentrations between 150 and 2000 ng g^?1) and another one based on the determination of organomercury chlorides (Approach B: a much more time‐consuming methodology, applicable to samples with methylmercury at 1.2–200 ng g^?1). Both procedures have been used together for the analysis of bivalves and fish samples. Copyright © 2005 John Wiley & Sons, Ltd.     

The Speciatipn of Mercury in Soil and Sediment

A systematic procedure for speciation of mercury in soil and sediment was established Experimental conditions were optimized,and interference between different species was studied.The procedure was applied to practical samples and the results obtained were satisfactory.     

Characterization of mercury species in soils by HPLC-ICP-MS and measurement of fraction removed by diffusive gradient in thin films

The properties and behaviour of Hg depend on both the oxidation state and the chemical form: the bioavailability, toxicity, persistence and accumulation of mercury in the food web are strongly influenced by chemical speciation. The present work aims to determine the chemical forms of mercury present in soil and to evaluate the fraction of mercury in soil solution available to plants. In order to do this, we analyzed eight samples of contaminated soils with Hg concentrations ranging from 1.31 to 21.7 mg kg⁻¹, collected from different depths (0–10 and 40–50 cm) close to an abandoned industrial site in Val Basento (southern Italy). Two innovative analytical techniques were used: HPLC–ICP-MS and diffusive gradient in thin films (DGT). The analytical procedure was validated using ERM 580-certified sediment and spiked samples in the case of HPLC–ICP-MS, and by a performance test in the case of DGT. In all samples, the only species found in soil and soil solution was MeHg⁺ and Hg²⁺. In soil, the MeHg⁺/Hg_tot ratio ranged from 0.05% to 0.82%; total mercury in soil solution was less than 0.01% of total mercury in soil. The percentage of MeHg⁺ in soil solution varied considerably (from 0% to 50%), with a maximum concentration of 0.02 mg L⁻¹. The root available concentration evaluated by DGT is comparable to the total mercury content of the soil solution measured by HPLC–ICP-MS. The DGT results suggest that all mercury in solution is available for uptake in DGT, and that mercury is supplied from soil to solution. However, for all samples the soluble and root available (DGT-labile) fractions of mercury are generally very low with respect to the total mercury concentration. This study confirmed that both HPLC–ICP-MS and DGT techniques are suitable tools for the estimation of Hg root availability and in assessing the risk from contaminated soils.     

Sequential extraction and thermal desorption of mercury from contaminated soil and tailings from Mongolia

Mercury forms in contaminated environmental samples were studied by means of sequential extraction and thermal desorption from the solid phase. The sequential extraction procedure involved the following fractions: water soluble mercury, mercury extracted in acidic conditions, mercury bound to humic substances, elemental Hg and mercury bound to complexes, HgS, and residual mercury. In addition to sequential extraction, the distribution of mercury species as a function of soil particles size was studied. The thermal desorption method is based on the thermal decomposition or desorption of Hg compounds at different temperatures. The following four species were observed: Hg⁰, HgCl₂, HgS and Hg^(II) bound to humic acids. The Hg release curves from artificial soils and real samples were obtained and their applicability to the speciation analysis was considered.      

Speciation Analysis of Mercury in Water and Human Urine Using Gas Chromatography-Mass Spectrometry after Solid Phase Disk Extraction

In recent years, there has been growing interest in the field of mercury speciation analysis. Mercury speciation analysis of water or urine matrices are necessary for solving various environmental, biological or clinical problems. Due to the complexity of sample matrices and the low levels of mercury species, an extraction step, such as liquid-liquid extraction or solid phase cartridge extraction, is required for Hg speciation analysis to isolate and enrich analyte species from sample matrices. As a new experimental configuration, disks or membranes for solid phase extraction (SPE) have been utilized in recent years for the preparation of many different organic and environmental samples. However,the literature survey revealed that solid-phase disk extraction has received little attention in the field of elemental speciation analysis.     

高效液相色谱-原子荧光光谱法应用于不同营养级鱼肌中汞的形态分析

汞是环境中最具威胁的元素之一,各形态汞的毒性不同,并且会随食物链的传递积累. 因此,同时检测鱼肌中不同形态的汞含量,并分析其在不同生境及营养级的差异性具有相当重要的研究价值. 通过高效液相色谱-原子荧光光谱联用法改变流动相中甲醇的浓度、光电倍增管负高压、空心阴极灯电流、还原剂及载流的浓度等条件,优化了不同汞形态组分的分离程度和响应值. 在优化的试验条件下,将鱼肌样品经离心、过柱、洗脱等步骤处理后,由液相色谱分离,最终通过原子荧光法检测提取溶液中3种汞形态. 结果表明,二价汞、甲基汞、乙基汞在0.2~10.0 μg/L质量浓度范围内线性关系良好,相关系数均大于0.999 9,方法检出限在0.39~0.82 μg/kg之间,平行样品相对标准偏差(RSD)均小于4.0%. 方法前处理简单,准确度高,适用于鱼肉中汞的形态分析. 方法应用于不同生境、不同营养级的鱼肌样品检测,可观察到不同营养级样品结果明显的差异性及同类样品间的相关性.     

Comparison of physicochemical speciation procedures with metal toxicity to chlorella pyrenoidosa

Metal speciation as measured by anodic stripping voltammetry (ASV), adsorption on a resin with adsorbed hydrated aluminium oxide, and dialysis with receiving resins is compared with the toxicity of the metals to the freshwater green alga Chlorella pyrenoidosa Chick. In the presence of natural and synthetic ligands, similar labile fractions of metals were obtained for ASV at three electrodes (hanging mercury drop electrode, mercury film electrode and Nafion-coated mercury film electrode). The toxic fractions determined by ASV and bioassay were in reasonable agreement for zinc, cadmium and copper, and alteration of the analytical conditions provided some measure of agreement for lead. The resin with adsorbed hydrated aluminium oxide correlated well with bioassay for copper, but over-estimated lead toxicity and under-estimated cadmium toxicity. Dialysis with receiving resins under-estimated metal bioaccumulation in the presence of ligands. Metal speciation analysis for water samples gave higher toxic fractions for metals in samples of polluted river water and road runoff samples than those found in pristine river water.