汞化合物的生物检测技术

为了对环境中的汞污染进行现场检测，需要开发简便、快速、灵敏的分析方法。生物检测技术是其中的一个重要研究方向。在分析中，对现有的汞化合物主要生物检测技术的原理、特点、研究现状及应用前景进行了评价。     

不同制备条件对生物焦汞吸附特性及吸附动力学的影响

为获得生物焦对汞的吸附特性,对不同制备条件下的生物焦进行研究。通过分析生物质种类、制备粒径、制备温度以及制备氧浓度对生物焦吸附汞的影响,并结合其吸附动力学过程,进一步探究吸附机理。结果表明:不同制备条件下生物焦汞吸附特性存在差异;生物焦对汞的物理吸附中,孔隙结构对其具有影响,累积孔体积越大,单位汞吸附量越高,利于生物焦对汞的吸附;与比表面积相比,比孔容积在汞吸附过程中发挥更为重要的作用;化学吸附与物理吸附均在生物焦汞吸附过程中起到重要影响,且化学吸附是其主要的控速步骤。     

松花江三岔河—哈尔滨江段汞污染分布状况的探讨

通过对松花江三岔河—哈尔滨江段水体、底泥、水生生物中总汞和甲基汞污染的研究,基本查清了三岔河—哈尔滨江段水体、底泥、水生生物中总汞和甲基汞含量范围;掌握了此江段汞的污染分布状况;“一松”江水对来自“二松”汞的净化情况;水生生物的汞污染水平与底质和江水汞含量之间的相关性、江水和水生生物含汞量的季节变化;甲基汞与总汞之间的变化关系。为松花江汞污染的防治途径,汞污染分布状况深入研究提供了必要的基础资料。     

汞污染防治仍是全球关注的热点

50年代发生的日本熊本水俣病事件曾一度引起对汞污染的全球性警惕。汞的生物转化和污染控制一直受到研究者的关注。由于汞及化合物是生物积累性毒物 ,直至今日 ,汞污染防治仍是各国关心的难题。联合国环境规划署 (UNEP)最近提出 ,将对世界范围内的汞污染源及其影响作调查研究 ,该项目预计在 2 0 0 3年完成 ,提出汞污染防治建议 ,包括减少或停用汞及其化合物 ,以尽量降低其排放量 ,对预防和控制汞污染技术进行评价 ,并推出汞的替代物。在美国 ,汞的主要污染源是燃煤电厂、废物焚烧和氯碱工业。据悉 ,美国经由大气沉降向全球环境输出的汞较…     

热解吸对污染土壤中不同形态汞的去除作用

选取贵州省万山矿区的汞污染土壤样品进行不同形态汞的热解吸去除行为研究。研究了热解吸过程中∑Hg的去除效果及动力学,以及温度和时间对污染土壤中不同形态汞的去除作用。结果表明,热解吸修复技术可有效去除土壤中的汞,土壤中∑Hg的热解吸过程符合二级动力学方程。固定热解吸时间在10 min时,随着热解吸温度的升高,土壤中水溶态汞、盐酸溶态汞和碱溶态汞含量呈现先下降后上升再下降的趋势,王水溶汞和盐酸溶态汞始终呈现下降趋势,说明不同形态的汞之间发生了转化。热解吸温度为250℃时,随着热解吸时间的增加,环境风险大的水溶态汞、盐酸溶态汞、碱溶态汞和硝酸溶态汞的去除率大幅增加,土壤的有机质损失较少,说明在低温下,延长热解吸时间,对生物毒性强的形态汞有良好的修复效果,且此温度下处理后的土壤更容易恢复农田耕作。     

原位生物修复治理汞害的机制及作用

概述植物、微生物在去除水、土壤中汞污染方面的有效性。介绍微生物固定、转化汞及其化合物的机制以及原位生物修复技术在治理汞害方面的作用     

蓟运河底质中甲基汞分布的变化趋势

一、前言 一些有机汞化合物具有慢性的毒理学性质,它比无机汞更毒。据瑞典科学家Jensen和Jerhelor首先指出,从工农业污染物中进入环境的多种形态的汞,可在天然汞的生态系统中转化成甲基汞.在国内外对沉积物中的汞的生物甲基化和鱼对甲基汞富集的研究工作已有报导。影响汞的生物甲基化的     

高浓度汞污染土壤低温工程性修复复垦的可行性

低温热解技术修复高浓度汞污染土壤(≥100 mg·kg~(-1))工程除汞效果可达70%以上,仍残留20%~30%的惰性汞,是否对农作物安全存在一定风险仍属未知。为此,以低温热解工程性修复前的高浓度汞污染农田土壤为对照,研究修复后土壤在原位大田条件下残留汞的形态变化及对几种常见作物生物产量、质量及汞在植物组织间迁移的影响。结果表明:低温热解过程未对土壤肥力造成影响,经低温热解修复后土壤中有机结合态汞降低64.07%,残渣态汞降低56.38%;高浓度汞污染抑制了作物生长,修复后土壤耕种作物生长状况得以明显改善,作物产量提高了2~3倍;所研究作物可食部分土豆肉、玉米粒及稻米,汞含量分别降低了51.2%、43.8%和53.79%;汞在植株中的分布情况为:根叶茎,残留汞对植株根系的胁迫最为严重,且植株的根和叶汞含量,相比修复前明显降低了2~5倍。     

不同吸附条件下生物炭的汞吸附特性研究

为了获得汞初始浓度、吸附温度以及气氛(O_2、CO_2、SO_2浓度)等不同吸附条件下生物炭的汞吸附特性,对等温和非等温条件下制备的核桃壳生物炭(分别记为WS_(iso)和WS_(var))进行了研究,并利用比表面积和孔隙度分析仪、傅立叶变换红外光谱仪表征生物炭的孔隙结构和表面官能团等微观特性,探究其影响机理。结果表明:WS_(iso)和WS_(var)孔隙结构及表面化学性质不同,其中WS_(iso)的累积孔体积较大,为0.130 8cm~3/g,WS_(var)的含氧表面官能团数量和种类较多;在相同吸附条件下,WS_(iso)的汞吸附效果整体上优于WS_(var);汞初始浓度、CO_2和O_2浓度的升高会对生物炭汞吸附性能起到促进作用;随着吸附温度和SO_2浓度的升高,生物炭的吸附性能有所下降。     

混汞法采金地区的汞污染研究进展

混汞法是一种设备简单、操作简便且应用历史悠久的提金方法 ,在世界范围内得到了普遍使用 ,同时也导致了严重的汞污染。本文介绍了混汞法的流程以及汞的释放过程和释放因子 ;综述了应用混汞法提金的不同国家和地区 ,对由此引发的大气、水体、生物 (包括人体 )和土壤汞污染的研究现状 ,并讨论了采金地区的环境管理政策     

Guidelines for routine mercury speciation analysis in seafood by gas chromatography coupled to a home-modified AFS detector. Application to the Andalusian coast (south Spain)

A home-modified atomic fluorescence detector (mAFS) has been employed for mercury and methylmercury determination in bivalves from the Andalusian coast (south Spain). This modification consists on the inclusion of a quartz flow cell into the detector, which increases the concentration of mercury atoms in the detector and therefore enhances sensitivity about two fold. Two analytical approaches for mercury speciation based on the coupling of gas chromatography on-line pyrolysis and mAFS (GC-Pyro-mAFS) have been tested. The first approach (Method 1) is based on aqueous ethylation followed by extraction into an organic solvent, and the second one (Method 2) in the extraction of monoalkylated mercury as chloride. Method 1 is a rapid procedure but not sensitive enough for the analysis of methylmercury in non-polluted sites (detection limit: 20 ng g(-1) as mercury, wet basis). The second one is quite more sensitive (detection limit: 0.2 ng g(-1), wet weight), but sample treatment is cumbersome and time-consuming. The optimum range for mercury determination for both methods are complementary and exhibit an overlapping measurable concentration range (OMCR) in which methylmercury can be indistinctly determined (75-100 ng g(-1) as mercury, wet basis). The suitability of both methods has been assayed with spiking experiences at levels within the OMCR with good recoveries. Both approaches have been validated with two certified reference materials (BCR-463, mercury and methylmercury in tuna fish; and NIST-2977, organic contaminants and trace metals in mussel tissue). Both procedures have been used for the analysis of three species of bivalve molluscs collected along the Andalusian coast (south Spain), all of them employed for human consumption (Chamelea gallina, Donax trunculus and Scrobicularia plana), and their potential use in routine analysis has been established.     

Relative accuracy testing of an X-ray fluorescence-based mercury monitor at coal-fired boilers

The relative accuracy (RA) of a newly developed mercury continuous emissions monitor, based on X-ray fluorescence, was determined by comparing analysis results at coal-fired plants with two certified reference methods (American Society for Testing and Materials [ASTM] Method D6784-02 and U.S. Environment Protection Agency [EPA] Method 29). During the first determination, the monitor had an RA of 25% compared with ASTM Method D6784-02 (Ontario Hydro Method). However, the Ontario Hydro Method performed poorly, because the mercury concentrations were near the detection limit of the reference method. The mercury in this exhaust stream was primarily elemental. The second test was performed at a U.S. Army boiler against EPA Reference Method 29. Mercury and arsenic were spiked because of expected low mercury concentrations. The monitor had an RA of 16% for arsenic and 17% for mercury, meeting RA requirements of EPA Performance Specification 12a. The results suggest that the sampling stream contained significant percentages of both elemental and oxidized mercury. The monitor was successful at measuring total mercury in particulate and vapor forms.     

International field intercomparison measurements of atmospheric mercury species at Mace Head,Ireland

Eleven laboratories from North America and Europe met at Mace Head, Ireland for the period 11–15 September 1995 for the first international field intercomparison of measurement techniques for atmospheric mercury species in ambient air and precipitation at a marine background location. Different manual methods for the sampling and analysis of total gaseous mercury (TGM) on gold and silver traps were compared with each other and with new automated analyzers. Additionally, particulate-phase mercury (Hg_part) in ambient air, total mercury, reactive mercury and methylmercury in precipitation were analyzed by some of the participating laboratories. Whereas measured concentrations of TGM and of total mercury in precipitation show good agreement between the participating laboratories, results for airborne particulate-phase mercury show much higher differences. Two laboratories measured inorganic oxidized gaseous mercury species (IOGM), and obtained levels in the low picogram m^-3 range.     

Recent advances in mercury speciation analysis with focus on spectrometric methods and enriched stable isotope applications

This paper discusses some recent advances in spectrometric methods and approaches for mercury speciation analysis of environmental samples with focus on isotope dilution techniques for determination of mercury species' concentrations in gaseous samples and reaction rates in soils and sediments. Such analytical data is important inter alia in fundamental research on mercury biogeochemistry and for risk assessments of mercury-contaminated soils and sediments and for designing effective remedial actions. The paper describes how the use of enriched stable isotope tracers in mercury speciation analysis can improve the traceability and accuracy of results, facilitate rational method developments, and be useful for studying biogeochemical processes, i.e. rate of reactions and fluxes, of mercury species. In particular the possibilities to study and correct for unwanted species transformation reactions during sample treatment and to study "natural" transformations of species in environmental samples, or micro- and mesocosm ecosystems, during incubations are highlighted. Important considerations to generate relevant data in isotope tracer experiments as well as reliability and quality assurance of mercury speciation analysis in general are also discussed.     

A practical and simple method in fractional determination of ambient forms of mercury in air

A collecting method to prepare a fractional determination of ambient forms of mercury in air is proposed. Particulate mercury is collected by a glass fiber filter. Sequential trap tubes consist of four long and slender quartz tubes, in which the Chromosorb W treated with HC$\text{l}$ gas for Hg(II), the Chromosorb W treated with 0.1 M NaOH for methylmercury, the silver-wire tip for metallic mercury and the gold plate tip for dimethylmercury are packed. The collection efficiency for these trap tubes was in the range of about 85 ～ 100% at the μg or ng concentration level. With this method, the air was collected by suction at the rate of 1.5 $\text{l}$/min. for about five hours, the detection limit being 0.2 ng Hg/m³. The results indicate that the regional distribution of total mercury in air was considerably greater in the volcanic and hot spring regions. Mercury species was found to be mostly Hg(II), followed by metallic mercury, methylmercury, dimethylmercury and particulate mercury in this order.     

Atmospheric mercury in the Great Smoky Mountains compared to regional and global levels

Improvements in measurement technology are permitting development of a more detailed scientific understanding of the cycling of mercury in the global atmospheric environment. Critical to advancing the state of knowledge is the acquisition of accurate measurement of speciated mercury (gaseous and particulate) at ground research stations in a variety of settings located around the globe. This paper describes one such research effort conducted at TVA's Look Rock air quality monitoring site in Tennessee—a mountain top site (813 m elevation) just west of the Great Smoky Mountains National Park. The Great Smoky Mountains National Park is the largest National Park in the eastern US and it receives environmental protection under a variety of US statutes. Gaseous and particle mercury species along with some additional trace gases were measured at Look Rock during two field studies totaling 84 days in the spring and summer of 2004. Average results for the entire sampling period are: gaseous elemental mercury Hg(0): 1.65 ng m⁻³, reactive gaseous mercury RGM: 0.005 ng m⁻³, particulate mercury Hg(p): 0.007 ng m⁻³. Literature review indicates that these levels are within the range found for other rural/remote sites in North America and worldwide. Reactive and particulate mercury comprised together less than 1%, on average, of total airborne mercury at Look Rock. When compared to the global background mercury literature, the Look Rock measurements demonstrate that the atmospheric mercury levels in the vicinity of the Great Smoky Mountains National Park are clearly dominated by the global atmospheric pool, not by local or regional sources.     

Routine, automated determination of inorganic and total mercury in multimedia using cold vapour atomic absorption spectrometry

A routine, automated analytical method for simultaneous determination of total and inorganic mercury by cold vapour atomic absorption spectrometry in multimedia is described. Excellent accuracy and precision results were obtained with human hair certified reference materials namely, BCR-397 and IAEA-086. The reproducibility relative standard deviation for total mercury was 4% and 22%, respectively. The limit of detection for total and inorganic mercury was 0.2 μg/g hair. The described method has been successfully applied in determination of total and inorganic mercury as well as organic mercury in human hair, urine and fish tissue samples.     

煤中汞及其对环境的影响

本文简要综述了煤中汞的分布规律、赋存状态、成因及燃烧过程中迁移转化和对环境的影响     

Control of mercury vapor emissions from combustion flue gas

GOAL, SCOPE AND BACKGROUND: Mercury (Hg) emission from combustion flue gas is a significant environmental concern due to its toxicity and high volatility. A number of the research efforts have been carried out in the past decade exploiting mercury emission, monitoring and control from combustion flue gases. Most recently, increasing activities are focused on evaluating the behavior of mercury in coal combustion systems and developing novel Hg control technologies. This is partly due to the new regulatory requirement on mercury emissions from coal-fired combustors to be enacted under the U.S. Title III of the 1990 Clean Air Act Amendments. The aim of this review work is to better understand the state-of-the-art technologies of flue gas mercury control and identify the gaps of knowledge hence areas for further opportunities in research and development. MAIN FEATURES: This paper examines mercury behaviors in combustion systems through a comprehensive review of the available literature. About 70 published papers and reports were cited and studied. RESULTS AND DISCUSSION: This paper summarizes the mechanisms of formation of mercury containing compounds during combustion, its speciation and reaction in flue gas, as well as subsequent mobilization in the environment. It also provides a review of the current techniques designed for real-time, continuous emission monitoring (CEM) for mercury. Most importantly, current flue gas mercury control technologies are reviewed while activated carbon adsorption, a technology that offers the greatest potential for the control of gas-phase mercury emissions, is highlighted. CONCLUSIONS AND RECOMMENDATIONS: Although much progress has been achieved in the last decade, techniques developed for the monitoring and control of mercury from combustion flue gases are not yet mature and gaps in knowledge exist for further advancement. More R&D efforts are required for the effective control of Hg emissions and the main focuses are identified.     

Comparative study of hotplate wet digestion methods for the determination of mercury in biosolids

The re-use of biosolids is becoming increasingly popular for land applications. However, biosolids may contain elevated levels of metals and metalloids (including mercury) relative to background environmental concentrations. Consequently, reliable mercury analysis is important to allow classification of biosolids and to determine appropriate options for beneficial uses. This paper reports on a comparative study of 12 hotplate wet digestion methods for their suitability for the determination of mercury in biosolids. The methods were applied to mercury biosolids samples from four localities of two different sewage treatment plants in the State of Victoria, Australia. Samples were also spiked with methylmercury chloride and mercury sulphide to evaluate the Hg recovery in each hotplate digestion method. Aqua regia (HCl:HNO(3)=3:1), reverse aqua regia (HCl:HNO(3)=1:3), nitric, hydrochloric, sulphuric acid and their combinations with or without hydrogen peroxide were studied as wet digestion solutions. The method providing the best mercury recoveries was optimized. Under optimal conditions the corresponding analytical procedure consisted of 1h pre-digestion of 0.4 g biosolids sample with 10 ml reverse aqua regia with temperature increasing to 110 degrees C and 3h digestion at this temperature. In the last 10 min of the digestion step, 2 ml hydrogen peroxide were added to ensure complete decomposition of all mercury containing compounds. After filtering and dilution with deionised water (1:10), the concentration of mercury was determined by cold vapour atomic absorption spectrometry. It is expected, that the wet acid digestion method developed in this study will be also applicable to biosolids from other sewage treatment plants and to other types of solid mercury samples with elevated levels of organic matter.