基于土壤汞形态归趋的健康风险评估方法

土壤汞污染是一个全球性关注问题,矿产资源开采、化工生产和燃煤发电等均造成了不同程度的土壤汞污染,合理评估汞污染场地的健康风险是场地开发再利用的关键.对土壤中汞的形态归趋研究总结表明,由于汞的特殊物理化学性质,并受土壤等环境因素的影响,导致其在土壤中具有复杂的化学形态和变化过程.汞在土壤中的不同化学形态归趋对其毒性效应、生物有效性和暴露途径产生显著影响.基于土壤汞总量的风险评估方法忽略了土壤中不同化学形态汞对毒性、生物有效性和暴露途径的影响,导致高估土壤汞污染的健康风险.针对基于土壤汞总量的风险评估存在的问题,提出了基于土壤汞形态归趋的土壤汞污染健康风险评估理论,并构建基于土壤汞形态归趋-有效剂量-健康效应的土壤汞污染的精细化风险评估技术体系框架:①土壤不同形态汞的测定与表征方法;②汞形态归趋预测模型;③暴露分析与暴露量计算;④有效剂量（生物可给性或生物有效性）测定;⑤风险表征;⑥基于不同形态汞的场地土壤污染风险筛选值和修复目标制定.该方法体系从理论上解决了传统基于土壤汞总量的风险评估方法存在的问题,实际应用中面临的主要问题和今后重点发展方向:①研发可商业化的土壤汞化学物组分分析仪及土壤汞蒸气的原位测定方法;②结合中国场地土壤特点,开展土壤中汞的形态归趋模拟的模型研究,弥补现阶段土壤汞化合物形态分析方法的欠缺;③研发和建立土壤汞的生物可给性和有效性的标准测试方法技术;④本土化的土壤汞筛选值的确定.      

三维荧光光谱研究溶解有机质与汞的相互作用

随着荧光光谱技术的进展,三维荧光光谱被广泛应用于研究各种天然水体中溶解有机质(包括腐殖质)的各种环境行为.本文利用三维荧光光谱和荧光猝灭滴定技术研究河流溶解有机质与Hg(Ⅱ)的相互作用.结果表明,溶解有机质中含有的3种类型荧光基团都能够不同程度地被Hg(Ⅱ)猝灭,并采用非线性回归分析拟合出Hg(Ⅱ)与3种荧光基团之间的条件稳定常数.pH值对Hg(Ⅱ)-DOM体系具有显著影响.Cl^-对Hg(Ⅱ)-DOM体系具有强烈的竞争作用.Ca(Ⅱ)能够使Hg(Ⅱ)-DOM体系荧光增强,而Mg(Ⅱ)对之影响很小.此外,Cu(Ⅱ)与Hg(Ⅱ)都是DOM的荧光猝灭剂,但是其猝灭机理存在差异.     

基于乡镇尺度的西南重金属高背景区土壤重金属生态风险评价

西南地区土壤重金属具有天然的高背景属性,在重金属高背景区开展生态风险评价和识别重金属潜在来源具有重要意义.以往工作主要以区域尺度的调查工作为主,调查精度难以满足空间规划和自然资源管理的需求,迫切需要在乡镇尺度上进行生态风险评价.云南省宣威市热水镇是典型的碳酸盐岩覆盖区,重金属来源复杂,潜在生态风险较高.本文在热水镇采集土壤表层样品(0～20 cm)1 092件,分析表层土壤中8种重金属(Cd、 Cr、 As、 Hg、 Pb、 Cu、 Zn和Ni)含量,采用统计学、地理信息系统、地累积指数、生态风险指数和正定矩阵因子分析模型(PMF)等方法开展生态风险评价和重金属源解析.研究发现,土壤中重金属Cd、 Cr、 Cu、 Hg、 Ni和Zn含量平均值和中位数均超过云南省土壤背景值,Cd、 Cr、 Cu和Ni平均含量均超过《土壤环境质量农用地土壤污染风险管控标准》(GB 15618-2018)规定的筛选值.地累积指数结果表明,研究区表层土壤污染最严重的是Cu,其次是Cr和Cd.土壤重金属Cr、 As、 Pb、 Cu、 Zn和Ni多以残渣态存在,多来自于地质背景,生物有效性较低,Hg的潜在有效组分较高,但是Hg全量较低,污染风险较小.Cd生物有效性比例较高,易于进入土壤溶液并被农作物吸收,是研究区污染风险最高的重金属元素.土壤重金属潜在生态风险指数统计结果显示,生态风险较低、中等生态危害和强生态危害比例分别为44.23%、 54.40%和1.37%,无很强生态危害样品,贡献率最高的元素为Cd和Hg,贡献率分别为34.62%和34.33%.PMF结果显示研究区重金属来源包括人类日常活动来源、自然来源、煤矿开采及交通排放引起的综合污染源和农业生产来源,各种来源的贡献率分别占9.29%、 53.67%、 11.23%和25.81%.PMF可以有效识别和量化污染物来源,为政府部门进行土地规划提供重要的参考依据.     

Study on the simultaneous reduction of methylmercury by SnCl2 when analyzing inorganic Hg in aqueous samples

Mercury (Hg) is among the most concerned contaminants in the world. It has three major chemical forms in the environment, including Hg⁰, Hg^2 +, and methylmercury (MeHg). Due to their differences in toxicity, mobility, and bioavailability, speciation analysis is critical for understanding Hg cycling and fate in the environment. SnCl₂ reduction-atomic fluorescence spectrometry detection is the most commonly used method for analyzing inorganic Hg. However, it should be noted that MeHg may also be reduced by SnCl₂, which would result in the overestimation of inorganic Hg. In this study, the reduction of MeHg by SnCl₂ in both de-ionized (DI) water and four natural waters was investigated. The results showed that MeHg could be reduced by SnCl₂ in DI water whereas this reaction was hard to occur in tested natural waters. By investigating the effects of water chemical characteristics (dissolved organic matter, pH and common anions and cations) on this reaction, SO₄^2 ? was identified to be the dominant factor prohibiting SnCl₂ induced MeHg reduction in natural waters. SO₄^2 ? in natural waters was evidenced to be reduced to S^2 ? by SnCl₂ and the generated S^2 ? can complex with MeHg to form MeHgS^? which is hard to be reduced by SnCl₂. Findings of this study indicate that the effect of MeHg reduction by SnCl₂ on inorganic Hg analysis is negligible in natural waters; however, at simulated experimental systems without SO₄^2 ?, SO₄^2 ? should be added as protecting agents to prevent MeHg reduction when analyzing inorganic Hg if it would not cause any other unwanted effects.     

Photo-induced transformations of Hg(Ⅱ) species in the presence of Nitzschia hantzschiana,ferric ion,and humic acid

Effects of algae Nitzschia hantzschiana, Fe(Ⅲ) ions, humic acid, and pH on the photochemical reduction of Hg(Ⅱ) using the irradiation of metal halide lamps (λ 365 nm, 250 W) were investigated. The photoreduction rate of Hg(Ⅱ) was found to increase with increasing concentrations of algae, Fe(Ⅲ) ions, and humic acid. Alteration of pH value affected the photoreduction of Hg(Ⅱ) in aqueous solution with or without algae. The photoreduction rate of Hg(II) decreased with increasing initial Hg(Ⅱ) concentration in aqueous solution in the presence of algae. The photochemical kinetics of initial Hg(Ⅱ) and algae concentrations on the photoreduction of Hg(Ⅱ) were studied at pH 7.0. The study on the total Hg mass balance in terms of photochemical process revealed that more than 42% of Hg(Ⅱ) from the algal suspension was reduced to volatile metallic Hg under the conditions investigated.     

Understanding the risks of mercury sulfide nanoparticles in the environment: Formation, presence, and environmental behaviors

Mercury (Hg) could be microbially methylated to the bioaccumulative neurotoxin methylmercury (MeHg), raising health concerns. Understanding the methylation of various Hg species is thus critical in predicting the MeHg risk. Among the known Hg species, mercury sulfide (HgS) is the largest Hg reservoir in the lithosphere and has long been considered to be highly inert. However, with advances in the analytical methods of nanoparticles, HgS nanoparticles (HgS NPs) have recently been detected in various environmental matrices or organisms. Furthermore, pioneering laboratory studies have reported the high bioavailability of HgS NPs. The formation, presence, and transformation (e.g., methylation) of HgS NPs are intricately related to several environmental factors, especially dissolved organic matter (DOM). The complexity of the behavior of HgS NPs and the heterogeneity of DOM prevent us from comprehensively understanding and predicting the risk of HgS NPs. To reveal the role of HgS NPs in Hg biogeochemical cycling, research needs should focus on the following aspects: the formation pathways, the presence, and the environmental behaviors of HgS NPs impacted by the dominant influential factor of DOM. We thus summarized the latest progress in these aspects and proposed future research priorities, e.g., developing the detection techniques of HgS NPs and probing HgS NPs in various matrices, further exploring the interactions between DOM and HgS NPs. Besides, as most of the previous studies were conducted in laboratories, our current knowledge should be further refreshed through field observations, which would help to gain better insights into predicting the Hg risks in natural environment.     

Functionalized CMK-3 mesoporous carbon with 2-amino-5-mercapto-1,3,4-thiadiazole for Hg(II) removal from aqueous media

Ordered mesoporous carbon（CMK-3） was synthesized and functionalized with 2-amino-5-mercapto-1,3,4-thiadiazole groups（AMT-OCMK-3） for Hg（Ⅱ） removal from aqueous solution. The modified CMK-3 was characterized by X-ray diffraction, N2adsorption-desorption isotherm, scanning electron microscopy and Fourier transform infrared spectroscopy. The effects of solution pH, contact time, initial Hg（Ⅱ） concentration and matrix effect were studied. The adsorption data were successfully fitted with the Langmuir model, exhibiting high adsorption capacity of 450.45 mg/g of AMT-OCMK-3. In the solid-phase extraction system a series of experimental parameters such as sample flow rate, sample volume,eluent volume and concentration of the eluent solution have been investigated and established for preconcentration of Hg（Ⅱ） in aqueous solution. The results showed that the enrichment factor for Hg（Ⅱ） was 250, the precision（relative standard deviation（RSD）, %） for six replicate measurements was 2.05% and the limit of detection for Hg（Ⅱ） was achieved at0.17 μg/L.     

硒和生物炭联合施用降低稻米甲基汞累积的研究

汞矿区土壤汞污染是造成水稻及其他作物中汞累积的主要原因,尤其是稻米中甲基汞的累积已成为当地居民甲基汞暴露的重要途径之一。本文针对含汞废水排放所造成的稻田汞污染情形,分别进行了模拟实验和盆栽试验,探究无机硒、生物炭、硒和生物炭联合施用对降低稻米甲基汞累积的作用效果。结果表明,无论向土壤中添加无机硒,还是生物炭,抑或是两者的组合均能有效降低土壤中甲基汞含量,且随着硒添加量的增加,其相应处理组土壤甲基汞含量不断降低。盆栽试验表明稻米中甲基汞含量因硒或生物炭的添加降低62%～73%（硒处理）、88%（生物炭处理）和90%～91%（硒+生物炭处理）,表明了硒和生物炭共同施用的作用效果要好于单独施用硒的作用效果。这种效果可能与生物炭降低了土壤中甲基汞的生物可利用性有关。总之,本研究为原位修复控制稻田汞污染风险提供了可能途径。     

Adsorptive removal of heavy metal ions from industrial effluents using activated carbon derived from waste coconut buttons

Removal of heavy metal ions from industrial effluents by the activated carbon prepared by steam activation of waste coconut buttons through batch adsorption process.     

地表环境汞污染的生物修复技术及展望

汞（Hg）及其化合物是一类重要的全球污染物，环境中高浓度的汞会对生态系统和人类健康造成严重危害。《关于汞的水俣公约》正式生效后，汞生产量、使用量和排放量将得到有效控制。然而历史排放汞导致的污染问题依然会对自然环境造成长期的生态风险，因此在减排的同时也亟需开发、发展有效治理汞污染的方法。本文总结了汞污染生物修复的技术及应用原理，分析了基于生物修复原理运用合成生物学手段改造生物将其运用到汞污染修复的优势和潜力，最后探讨了汞污染合成生物学修复应重点关注的问题和前沿研究方向。     

Hg在玲珑金矿区典型农田土壤中的吸附特征研究

采集烟台玲珑金矿区不同性质的土壤,通过吸附解析实验研究了矿区2种典型农田土壤对重金属汞的吸附特征.等温吸附-解吸实验结果表明,酸性土壤对Hg（Ⅱ）的平均吸附率高于中性土壤,中性土对Hg（Ⅱ）的最大吸附量为156.9μg/g,酸性土达到201.38μg/g.2种土壤结合Hg（Ⅱ）的解吸量和解吸率都较低,且酸性土的解吸率（...     

基于双模型的星云湖沉积物重金属溯源及风险评价

为了解星云湖沉积物中重金属污染现状,并为湖区污染防治提供理论依据,通过分析湖区表层沉积物中Cu、Zn、Pb、Ni、Cr、Cd、As、Hg等重金属含量,研究了其风险特征及污染来源组成.结果表明:①仅Ni、Cu含量尚未超过星云湖的背景值,其余元素均出现累积,Hg含量是星云湖背景值的2.13倍,潜在生态风险最高.②星云湖沉积物中重金属的空间分布与入湖河流和湖盆地势相关,表现出由河流输送向湖心扩散的趋势,高浓度区均分布在湖心深水区和特定河口位置,Hg的分布异于其他元素,呈西北湾>南部>中部的特征.③西北湖湾潜在生态风险最高,Cd、As是主要贡献元素.④星云湖沉积物中重金属主要来自自然源（占比为43.32%）、工业源（占比为25.89%）、农业源（占比为20.52%）和交通源（占比为10.27%）.研究显示,星云湖自然源重金属污染贡献最大,人为源相对较低,但湖区重金属污染处于较高水平.星云湖的重金属污染生态风险可能会持续加剧,其中Hg是污染防控的重点.      

贵阳市燃煤烟气中汞在大气中传输的数值模拟

利用中尺度非静力大气化学模式(MESO-NHC),以及目前大气中臭氧(O₃)和氢氧基(OH)对汞氧化的研究成果,研究贵阳市原煤燃烧产生的大气汞传输,以及φ(大气汞)对Hg0的干沉积速率,OH与元素汞(Hg0)的反应率常数的敏感性. 结果表明:①模拟区内实际大气中φ(Hg0)为局地人为排放源和自然排放源共同作用的结果,二者所占比例大致相当. ②由于化学和沉积特性不同,φ(Hg0),φ〔Hg(Ⅱ)〕和φ(HgP)随着与排放源距离增加而衰减的程度存在差异,排放源对附近地区φ(大气汞)及各种形态汞所占比例影响较大;在远离排放源的地方,大气中的Hg(Ⅱ)和HgP主要来自于Hg0不断的氧化作用. ③φ(大气汞)表现出2种不同的垂直分布特征,在一定高度以下φ(Hg0)随高度线性递减,而在该高度之上直到对流层顶φ(Hg0)几乎保持同样的数值;φ〔Hg(Ⅱ)〕和φ(HgP)随高度的变化遵循指数递减规律. φ(Hg0)随高度和与排放源距离增加而衰减的程度不及φ〔Hg(Ⅱ)〕和φ(HgP),主要是由于Hg0通过化学反应和沉积而离开大气的量少,能较充分通过平流扩散和垂直输送作用输送到离排放源较远和较高的地方. ④排放源附近φ(大气汞)较高的地方φ(大气汞)对Hg0的干沉积速率敏感性较高,而φ(大气汞)较低的地方其敏感性较低. ⑤φ(大气汞)对Hg0被OH氧化的反应率常数(k)的变化普遍很敏感,在较大的反应率常数kHg-OH3.55×10-14×e294/T情况下,Hg0所占比例偏低,而Hg(Ⅱ)和HgP所占比例偏高,与监测结果偏差较大;在kHg-OH2.94×10-14情况下模拟结果更为合理.      

Effects of methyl-, phenyl-, ethylmercury and mercurychlorid on immune cells of harbor seals （Phoca vitulina）

Mercury (Hg) is present in the marine environment as a natural metal often enhanced through human activities. Depending on its chemical form, Hg can cause a wide range of immunotoxic e ects. In this study, the influence of methyl-, ethyl- and phenylmercury as well as mercurychloride on immune functions was evaluated. Two parameters of cellular immunity, proliferation and mRNA cytokine expression of interleukin-2, -4, and transforming growth factor , were investigated in harbor seal lymphocytes after in vitro exposure to Hg compounds. While all Hg compounds had a suppressive e ect on proliferation, di erences between juvenile and adult seals were found. Lymphocytes from juveniles showed a higher susceptibility to the toxic e ect compared to lymphocytes from adults. Furthermore, the degree of inhibition of proliferation varied among the four Hg compounds. The organic compounds seem to be more immunotoxic than the inorganic compound. Finally, for the cytokine expression of methylmercury-incubated lymphocytes, timedependent changes were observed, but no dose-dependency was found. Marine mammals of the North Sea are burdened with Hg, and lymphocytes of harbor seals may be functionally impaired by this metal. The present in vitro study provides baseline information for future studies on the immunotoxic e ects of Hg on cellular immunity of harbor seals.     

Biochar affects methylmercury production and bioaccumulation in paddy soils: Insights from soil-derived dissolved organic matter

Biochar has been used increasingly as a soil additive to control mercury (Hg) pollution in paddy rice fields. As the most active component of soil organic matter, soil dissolved organic matter (DOM) plays a vital role in the environmental fate of contaminants. However, there are very few studies to determine the impact of biochar on the Hg cycle in rice paddies using insights from DOM. This study used original and modified biochar to investigate their effect on DOM dynamics and their potential impact on methylmercury (MeHg) production and bioaccumulation in rice plants. Porewater DOM was collected to analyze the variations in soil-derived DOM in paddy soils. The results showed that the addition of biochar, whether in original or modified form, significantly reduced the bioaccumulation of MeHg in rice plants, especially in hulls and grains (p<0.05). However, MeHg production in soils was only inhibited by the modified biochar. Biochar addition induced a significant increase in DOM's aromaticity and molecular weight (p<0.05), which decreased Hg bioavailability. Furthermore, enhanced microbial activity was also observed in DOM (p<0.05), further increasing MeHg production in the soil. Thus, the effect of biochar on the fate of Hg cycle involves competition between the two different roles of DOM. This study identified a specific mechanism by which biochar affects Hg behavior in rice paddy soil and contributes to understanding the more general influence of biochar in agriculture and contaminant remediation.     

A GFP-based bacterial biosensor with chromosomally integrated sensing cassette for quantitative detection of Hg(II) in environment

A mercury biosensor was constructed by integrating biosensor genetic elements into E. coli JM109 chromosome in a single copy number, using the attP/attB recombination mechanism of λphage. The genetic elements used include a regulatory protein gene (merR) along with operator/promoter (O/P) derived from the mercury resistance operon from pDU1358 plasmid of Serratia marcescens. The expression of reporter gene gfp is also controlled by merR/O/P. Integration of the construct into the chromosome was done to increase the stability and precision of the biosensor. This biosensor could detect Hg(II) ions in the concentration range of 100-1700 nmol/L, and manifest the result as the expression of GFP. The GFP expression was significantly different (P ≤ 0.05) for each concentration of inducing Hg(II) ions in the detection range, which reduces the chances of misinterpretation of results. A model using regression method was also derived for the quantification of the concentration of Hg(II) in water samples.     

Volcanic mercury in Pinus canariensis

Mercury (Hg) is a toxic element that is emitted to the atmosphere by both human activities and natural processes. Volcanic emissions are considered a natural source of mercury in the environment. In some cases, tree ring records taken close to volcanoes and their relation to volcanic activity over time are contradictory. In 1949, the Hoyo Negro volcano (La Palma-Canary Islands) produced significant pyroclastic flows that damaged the nearby stand of Pinus canariensis. Recently, 60 years after the eruption, we assessed mercury concentrations in the stem of a pine which survived volcano formation, located at a distance of 50 m from the crater. We show that Hg content in a wound caused by pyroclastic impacts (22.3 μg kg^?1) is an order of magnitude higher than the Hg concentrations measured in the xylem before and after the eruption (2.3 μg kg^?1). Thus, mercury emissions originating from the eruption remained only as a mark—in pyroclastic wounds—and can be considered a sporadic and very high mercury input that did not affect the overall Hg input in the xylem. In addition, mercury contents recorded in the phloem (9.5 μg kg^?1) and bark (6.0 μg kg^?1) suggest that mercury shifts towards non-living tissues of the pine, an aspect that can be related to detoxification in volcanism-adapted species.     

封闭式城市生活垃圾填埋场向大气释放汞的途径

利用自动测汞仪和动力学通量箱技术,对武汉市某生活垃圾填埋场封闭的扩建部分向大气释放汞的途径进行了研究.结果发现,封闭式垃圾填埋场释放汞的途径主要是通过地表,而排气筒的释放很小.观测期间地表汞的释放强度平均为(192.5±245.3)ng·(m²·h)^-1,比世界背景区域高出1～2个数量级.释放过程具有明显的昼夜变化规律,白天高于夜间,并在午间达到峰值.光照强度与汞释放通量间的相关性最高,达到0.77,说明Hg(Ⅱ)的光致还原作用是挥发态Hg0生成的主要途径.垃圾填埋场排气筒释放的气体中Hg0的平均浓度为7.0～68.9 ng.m^-3,远低于运行中的垃圾填埋场,并且流速也很小.     

大气汞的自然来源研究进展

大气汞在全球汞循环中占有极其重要的地位,对大气汞的研究是近15年来汞生物地球化学领域的热点,其中大气汞的来源又是大气汞循环演化过程研究的关键。大气汞的来源分为人为源和自然源。与人为汞源不同,大气汞的自然来源影响因素较多,对其认识的复杂性更强,进行准确的认识需进行大量的研究工作。本文综述了近十几年来大气汞自然来源的研究工作,对大气汞的各种自然来源及其影响因素进行了介绍,并对该领域未来的研究作了展望,希望能对以后的工作起一定的参考作用。     

万山汞矿区地表与大气界面间汞交换通量研究

采用动力学通量箱与高时间分辨率大气自动测汞仪联用技术对万山汞矿区不同季节、不同地表与大气界面间汞交换通量和大气汞含量进行了测定.结果显示,受人为活动和地表强烈释汞的影响,万山地区大气汞含量高出背景区1～3个数量级,在冶炼厂附近平均值可达1 101.8 ng/m³,最低平均值达17.8 ng/m³,显示万山汞矿区已遭受较严重的大气汞污染.万山汞矿区土壤与大气界面汞交换非常强烈,土壤向大气的释汞通量最高可达27 827 ng/(m².h),大气汞干沉降通量最高可达9 434ng/(m²·h).万山汞矿区土壤与大气汞交换通量主要受光照强度、大气汞含量影响.光照在土壤释汞过程中起促进作用,而较高的大气汞含量则抑制了土壤向大气的释放,并导致大气汞强烈的干沉降.不同的地表类型对地表释汞影响较大,植被覆盖土壤释汞通量显著低于无植被覆盖地区,而冶炼后的矿渣堆则成为大气汞的净源.