土壤中砷的形态分析和生物有效性研究进展

土壤砷污染是当今全球十分严重的环境与健康问题之一。土壤砷形态及生物有效性研究是开展污染诊断、评估环境健康风险及开展砷污染土壤修复的重要依据。目前土壤砷形态的研究方法包括化学选择性提取操作定义法、溶剂提取仪器测定或吸附材料选择性分离法和同步辐射X射线近边能谱（XANES）直接测定法，这些方法相互结合在土壤砷的形态转化研究中发挥着重要作用。目前关于生物有效性研究存在多种方法并存的局面，化学提取法相对经济、方便，但存在很大的局限性，往往不能真实反映土壤砷的有效态含量，只能作为环境危害程度识别的参考；植物指示法需选择敏感性植物方能有效地指示土壤砷对环境与健康的潜在危害；土壤动物与微生物指示法代表了未来开展砷污染早期预警的发展方向，具有广阔的应用前景。模拟肠胃液提取法(In Vitro Gastrointestinal Method)比较接近动物或人体对土壤砷污染的真实吸收状态，在环境健康风险评价中发挥着重要作用。目前国外已发展出采用兔、仔猪和猴的动物模型以研究经口摄入的生物有效性砷，但尚不清楚哪种动物模型更能准确反映砷对人体的生物有效性。     

铁硫化物矿物对地下水中砷的净化作用

<正>砷及其化合物是环境中的高毒物质,它们主要通过水体暴露危害人体健康(肖唐付等,2001;王薇等,2005),长期饮用高砷水,会引起黑脚病、神经痛、血管损伤以及增加心脏病发病率,肝肿大甚至发生肝硬化。世界卫生组织1993年修订     

小分子有机酸与砷络合的光谱特征

<正>砷(As)是有毒的类金属元素,普遍存在于大气、土壤、岩石以及水体中。人类活动,如:对矿石的开采冶炼、化工生产以及杀虫剂的使用等都会造成砷在环境中的积累[1]。目前全球性的砷环境健康风险主要来源于地下水中砷的长期低剂量暴露,因此关于砷在地下水体中迁移转化规律的研究,对砷污染控制显得     

砷的地球化学特征与研究方向

砷的毒性在古代就因砒霜而广为人知,国际癌症研究会将砷列为第一类致癌物。目前,世界上有数以百万计的人受到砷中毒的威胁,砷污染事件在世界范围都有报道。环境中的砷的来源很复杂,有自然因素引起的砷污染(主要是地质成因砷污染),也有人为活动带来的砷污染,还有二者共同作用形成的砷污染。此外,砷还可以通过各种自然的地球化学过程和生物过程进行迁移转化,直接或间接对人和动物等产生危害。文章从砷的来源与分布、砷的毒性和危害、砷的迁移转化、生物在砷循环中作用的新认识等方面进行论述,并针对目前国内外砷污染研究现状,提出在已有研究基础上,建议在河套地区进一步开展砷元素地球化学及人体健康关系研究。     

水稻对砷吸收的机理及控制砷吸收的农艺途径研究进展

全世界约一半人口以大米为主食,亚洲人口主食对水稻的依赖程度甚至超过90%。当前全球各地均存在不同程度的砷(As)污染,水稻容易在籽粒中积累砷,从而使砷通过食物链进入人体,威胁人体健康。水稻中砷含量水平为几个到几百个ng/g不等,砷从土壤进入水稻的过程涉及复杂的物理化学过程和形态转化,最终主要以砷酸、亚砷酸及砷的巯基、甲基配位等形态储存于大米中。田间水管理、施肥以及添加土壤改良剂等方法都可以控制稻田农田生态系统中水稻对砷的吸收,但是每种技术都有其优势和局限性。水稻农田生态系统中砷生物地球化学及水稻对砷的吸收和代谢等诸多因素都影响着水稻及谷粒中砷的浓度。综合考虑农艺活动对土壤中pH、氧化还原条件、有机质结构和共存元素等因素的影响,考虑不同的地域特征和经济因素,是在生产实践中实现控制水稻对砷吸收的关键。综合运用多种农艺方法进行水稻耕作是未来控制水稻吸收砷的重要途径;新型农艺方法在控制水稻吸收砷过程中的应用,气候变化对大米吸收砷的影响,以及非破坏原位与活体分析技术在砷形态分析中的应用,是未来在全球尺度上更科学有效地控制大米中的砷含量、降低人体砷暴露风险的关键,也是未来的重点发展方向和艰巨挑战。     

利用体外方法评估不同淋洗剂对土壤中砷的淋洗效果及其健康风险

土壤砷污染已成为我国严重的环境问题,淋洗法是修复土壤砷污染较为有效的手段之一。文中以砷污染土壤为研究对象,运用2种环境友好的淋洗剂KH2PO4和草酸进行振荡淋洗实验,探究两种淋洗剂对不同砷污染土壤的淋洗效果,在此基础上,通过2种不同的体外方法 (physiologically based extraction test,PBET;in vitro gastrointestinal,IVG),探索其生物可给性及对人体的健康风险。结果显示,KH2PO4和草酸对土壤中砷有不同程度的去除,草酸对土壤砷的去除率较高,平均去除率为54.3%。运用PBET方法得到的土壤砷的生物可给性高于IVG方法,KH2PO4淋洗后土壤砷的生物可给性高于草酸。与草酸相比,KH2PO4淋洗会在一定程度上增加土壤砷的健康风险。不同in vitro方法对不同淋洗剂修复后效果有不同的评估结果,应该根据不同的淋洗剂选择较为保守的体外方法来评估淋洗后土壤的生物可给性及健康风险。     

山东省烟台地区土壤重金属的生态效应——以砷为例

烟台市是山东半岛蓝色经济区核心城市之一,通过对山东省烟台市生态地球化学资料的系统整理,研究土壤重金属污染现状与分布迁移规律,发现土壤主要污染因子是As、Cd、Hg、Cu、Pb、Zn等重金属元素污染,工矿三废排放是土壤重金属污染的主要原因;主要致污因子砷是环境中毒性最大的有害元素之一。土壤-苹果树体系中As迁移及形态转化规律为:植物根系吸收土壤中的砷,并在根部发生了AsⅤ→AsⅢ的还原作用,由植物的根部向上迁移过程中,AsⅢ的比例逐渐降低。砷在根系土-植物体系中的分布为:根系土>根>叶子>茎>苹果。     

煤矿塌陷区复垦土壤环境质量评价

通过对煤矿塌陷区复垦土壤采样测试,研究土壤中重金属铜、锌、镉、汞、砷、铅、铬的含量对土壤环境的影响。研究结果表明:按单因子污染指数法和内梅罗综合污染指数法,结合国家土壤环境质量标准对复垦土壤的质量进行评价:研究区内土壤环境质量良好,基本上可以达到国家土壤环境质量二级标准,安全清洁级别;参照《无公害食品蔬菜产地环境条件标准》、《绿色食品产地环境质量标准》和《有机农业生产基地环境质量标准》,对复垦土壤的农用环境进行评价:研究区内土壤全部达到绿色食品产地环境质量标准,如果选择合理的修复方法,对部分有轻微污染的土壤进行,则可以达到有机农业生产基地环境质量标准;以潜在生态危害指数RI分析,复垦区内土壤重金属潜在生态危害指数相对较低,复垦区农业生产具有良好的发展前景。     

高砷含水层沉积物矿物学特征及砷的活化

利用X射线衍射和X射线荧光分析、沉积物序列提取试验及矿物饱和度的计算,对采自江汉平原中部沙湖地区典型高砷含水层钻孔沉积物样品矿物学进行了分析,并讨论了控制含水层中砷释放和迁移的地球化学机制.对矿物在沉积物与土壤中的分布及组成的对比分析,在一定程度上指示了矿物赋存环境和/或高砷水形成的环境背景:土壤与沉积物中高岭石以低于其他3种粘土矿物的含量普遍存在,指示了含水层沉积物形成过程江汉平原存在一定的湿热古气候环境;沉积物绿泥石含量低于土壤中绿泥石,恰恰反映了土壤比沉积物略强的碱性环境;沉积物中黄铁矿的存在,显示了含水层局部的强还原性环境,指示地下水中广泛存在的Fe2+容易与二价硫发生沉淀并结合砷.砷主要以无定形铁锰氧化物结合态(平均在31％以上)形式存在,其次以碳酸盐和有机质结合态存在.无定形铁锰氧化物的还原溶解可能是控制砷迁移到地下水中主要的地球化学机制.相对高含量的绿泥石容易在含水层中发生风化,其溶解过程可以将铁释放到地下水中,从而成为影响地下水中砷活化的潜在因素.     

硫酸盐还原作用调控下砷的环境地球化学行为

<正>天然环境中砷的形态转化与环境的化学条件和生物条件密切关联,铁与硫是影响砷环境行为的重要元素,尤其微生物硫酸还原作用对砷的形态转化具有重要的调控作用。本研究以淹水土壤为例研究了厌氧微生物作用下砷,铁,硫元素的环境行为,及次生产物的相互作用下砷的再分配过程,重点考察硫酸盐还原作用对砷环境行为的影响。研究发现在加硫和无硫添加体系中微生物还原作用都造成了体系中85%以上砷酸盐被转化为亚砷酸盐。在无硫添加体系中微生物促进了砷的释放,释放的砷以是亚砷酸盐为主要形态,在培养     

西藏搭格架高温热泉中砷的地球化学异常及其存在形态

西藏搭格架高温热泉是我国大陆少有的大型间歇性喷泉,砷元素作为对人类威胁极大的环境问题普遍存在于热泉之中,搭格架高温热泉中砷元素质量浓度最高已达到了9.75 mg/L,其对地表水和浅层地下水的污染不容忽视。硫代砷是富含硫化物热泉中砷的存在形态之一,鉴于国内相关研究较少,本文对西藏搭格架地热区的热泉样品进行了水化学分析,并利用水文地球化学模拟软件PHREEQC开展了对热泉中砷元素存在形态的地球化学模拟。结果表明：西藏搭格架热泉中砷元素的存在形态有亚砷酸盐、砷酸盐和硫代砷,其中亚砷酸盐与砷酸盐是砷的主要存在形态,且在pH影响下两者之间存在相互转化关系;各种硫代砷按质量浓度由高至低依次为一硫代砷酸盐、三硫代砷酸盐、二硫代砷酸盐、一硫代亚砷酸盐、四硫代砷酸盐;硫代砷形态占总砷浓度比例主要受热泉中硫化物质量浓度、Eh（氧化还原电位）和pH等因素的控制,在硫化物质量浓度总体偏低的情况下,硫化物质量浓度的上升可促进其他形态的砷向硫代砷形态转化,强还原性环境有利于硫代砷形态的存在;此外,在中性环境下,硫代砷占总砷浓度比例随pH上升亦有上升趋势。     

煤中砷的赋存状态

砷是煤中常见的有害微量元素,由于其丰度较低,定量研究其赋存状态一直很困难。近年来,采用逐级化学提取实验方法对煤中不同赋存状态的砷进行了定量研究,综合分析这些研究可得出以下结论：①煤中砷的赋存状态包括硫化物态砷、有机态砷、砷酸盐态砷、硅酸盐态砷、水溶态和可交换态砷。总体上,硫化物态砷＞有机态砷＞砷酸盐态砷＞硅酸盐态砷＞水溶态和可交换态砷,但在不同的煤样品中,也表现出较大的差异性。②一般而言,煤中大部分砷存在于含砷黄铁矿中,含砷黄铁矿中的砷含量与黄铁矿的成因或类型有关。煤中的砷酸盐态砷主要与铁氧化物和氢氧化物共生;硅酸盐态砷主要进入粘土矿物晶格。③在砷含量较低的煤样品中,有机态砷含量较高,其中在褐煤和低煤级烟煤中,可提取出与腐殖酸和富里酸结合的砷。当前还难以确认有机态砷的化学结构。④贵州特高砷煤中砷的赋存状态较为复杂,在某些样品中与氧结合的有机态砷为主要的赋存状态。     

Role of Quaternary stratigraphy on arsenic-contaminated groundwater from parts of Middle Ganga Plain,UP–Bihar,India

Late Quaternary stratigraphy and sedimentation in the Middle Ganga Plain (MGP) (Uttar Pradesh–Bihar) have influenced groundwater arsenic contamination. Arsenic contaminated aquifers are pervasive within narrow entrenched channels and flood plains (T₀-Surface) of fine-grained grey to black coloured argillaceous organic rich Holocene sediments (Newer Alluvium). Contaminated aquifers are often located close to distribution of abandoned or existing channels and swamps. The Pleistocene Older Alluvium upland terraces (T₂-Surface) made up of oxidized yellowish brown sediments with calcareous and ferruginous concretions and the aquifers within it are free of arsenic contamination. MGP sediments are mainly derived from the Himalaya with minor inputs from the Peninsular India. The potential source of arsenic in MGP is mainly from the Himalaya. The contaminated aquifers in the Terai belt of Nepal are closely comparable in nature and age to those of the MGP. Arsenic was transported from disseminated sources as adsorbed on dispersed phases of hydrated-iron-oxidea and later on released to groundwater mainly by reductive dissolution of hydrated-iron-oxide and corresponding oxidation of organic matter in aquifer. Strong reducing nature of groundwater is indicated by high concentration of dissolved iron (11.06 mg/l). Even within the arsenic-affected areas, dugwells are found to be arsenic safe due to oxyginated nature.     

Arsenic in groundwater affected by phosphate fertilizers at São Paulo, Brazil

. This paper studies metalloid mobility in soils produced by conventional farming methods. The mobility of arsenic in soils depends on several factors including redox potential, soil mineralogy, pH, and the presence of other anions that compete with As for soil retention sites, for example, phosphate. Phosphate enhances the mobility of As in soils by competing for adsorption sites. Arsenic may accumulate in soil through the application of fertilizers. Ingestion of inorganic arsenic contained in drinking water is known to cause cancer. Studies were carried out in an area of Jundiaí, São Paulo in Brazil with high arsenic levels in natural water from domestic wells. The mobility of arsenic in the soil of Jundiaí was studied in the period 1998–2001. The application of phosphate fertilizers on a wide scale is a common agricultural practice. Based on data from the field and laboratory experiments, the deterioration of soil and groundwater quality is a result mainly of fertilizer use due to excessive P application, overdosing of soil with phosphate, and undesirable additions of arsenic in P fertilizers.     

A geochemistry study of arsenic speciation in overburden from Mae Moh Lignite Mine, Lampang, Thailand

The aim of this study was to investigate the geochemical characteristics of arsenic in the solid material samples of the Mae Moh Mine and also the Mae Moh power plants fly ash samples were systematically studied. Arsenic concentration in overburden, coal lignite and fly ash are variable (depending on source of solid samples). The results show that the strata of overburden, J seam of coal and fly ash are rich in arsenic and also relatively soluble from fly ash; it occurs as a surface precipitate on the ash particle. The experimental study on speciation in the strata also indicates that the arsenic speciation of Mae Moh solid samples are mainly arsenate, As (V), which are approaching exceed 80%. Arsenic content in the main of overburden is in the range of 14.3–888.8 mg/kg, which is larger than the arsenic background soil values. Solid materials polluted wastewater; the arsenic speciation was present predominantly as arsenate in the surface water of a series of Mae Moh solid materials basins.     

Arsenic hyperaccumulation by brake ferns and their potential in phytoremediation

Municipal solid waste incinerator （MSWI） fly ash is world-widely defined as hazardous waste because of its high concentration of heavy metals and high toxic equivalents of dioxin-like compounds. Therefore, if not properly disposed, it would pose a risk of being released into the environment including soil and groundwater. Heavy metals in the MSWI fly ash are considered as the most dangerous component owing to their leaching characteristics and migration capability. To get a better knowledge of their releasing behavior, it is important to assess the potential environmental mobility of heavy metals in MSWI fly ash and to investigate the factors affecting their leaching characteristics. Fly ashes from four MSW incinerators were characterized and leaching of heavy metals according to both Chinese HVEP and USA TCLP were performed. A geochemical modeling computer program, PHREEQC （version 2） was used to calculate the equilibrium concentration, the speciation and possible precipitation of heavy metals in the leaching systems. In the modeling, the heavy metals, Cd, Cr, Cu, Ni, Pb, Zn, were input as master aqueous species in solutions, while the major and accessory components, Ca, Na, K, Cl, S, etc., were defined as finite solids. The agreement between the experimental results and the modeling ones varies for different metals as well as for different fly ashes. In general, the fitness of the modeling for different heavy metals is： Pb〉Zn〉Cd〉Cu. The modeling is excellent for fly ashes with low calcium but high chloride content, or with high concentration of heavy metals, which favor the implicit postulation of component input in the modeling, i.e., high availability of heavy metals.     

Arsenic Levels in Groundwater from Quaternary Alluvium in the Ganga Plain and the Bengal Basin, Indian Subcontinent: Insights into Influence of Stratigraphy

Late Quaternary stratigraphy and sedimentation in the Ganga Alluvial Plain and the Bengal Basin have influenced arsenic contamination of groundwater. Arsenic contaminated aquifers are pervasive within lowland organic rich, clayey deltaic sediments in the Bengal Basin and locally within similar facies in narrow, entrenched river valleys within the Ganga Alluvial Plain. These were mainly deposited during early-mid Holocene sea level rise. Arsenic was transported from disseminated sources as adsorbed on dispersed phases of hydrated-iron-oxide. These were preferentially entrapped as sediment coatings on organic-rich, fine-grained deltaic and floodplain sediments. Arsenic was released later to groundwater mainly by reductive dissolution of hydrated-iron-oxide and corresponding oxidation of sediment organic matter. Strong reducing nature of groundwater in the Bengal Basin and parts of affected middle Ganga floodplains is indicated by high concentration of dissolved iron (maximum 9-35 mg/l). Groundwater being virtually stagnant under these settings, released arsenic accumulates and contaminates groundwater. The upland terraces in the Bengal Basin and in the Central Ganga Alluvial Plain, made up of the Pleistocene sediments are free of arsenic contamination in groundwater. These sediments are weakly oxidised in nature and associated groundwater is mildly reducing in general with low concentration of iron (<1 mg/l), and thus incapable to release arsenic. These sediments are also flushed free of arsenic, released if any, by groundwater flow due to high hydraulic head, because of their initial low-stand setting and later upland terraced position.     

Arsenic in the Muteh gold mining district, Isfahan, Iran

Following the appearance of symptoms of arsenic toxicity in the inhabitants of villages in the Muteh gold mining region, central Iran, the concentration of this element in various parts of biogeochemical cycle is investigated. For this purpose, rock, groundwater, soil, plant, livestock hair and wool, and human hair samples are collected and analysed. Total arsenic content ranges from 23 to 2,500?mg/kg in rock samples, 7?C1,061???g/l in water, 12?C232?mg/kg in soil, 0.5?C16?mg/kg in plant samples, 4.10?C5.69?mg/kg in livestock hair and wool, and 0.64?C5.82?mg/kg in human hair. Arsenic concentration in various parts of biogeochemical cycle near the gold deposit in a metamorphic complex, and also close to the gold-processing plant, is very high and decreases exponentially with increasing distance from them. Arsenic concentration in water from a well close to the Muteh gold mine is above 1?mg/L. Arsenic in hair samples taken from local inhabitants is above the recommended levels, and the control samples in Shahre-Kord city. Arsenic concentration is higher in male population and correlates positively with age. It is suggested that arsenic resulting from the decomposition of ore mineral such as orpiment (As₂S₃), realgar (As₂S₂) and arsenopyrite (FeAsS) is responsible for polluting natural resources and the human intake via drinking water and the food chain. Gold mining and processing has undoubtedly enhanced the release of arsenic and intensified the observed adverse effects in Muteh area.     

内蒙古河套地区多目标区域地球化学调查成果及其意义

报道了内蒙古河套地区多目标区域地球化学调查结果及其对当地资源勘察、古湖泊环境、城市污染和地方病研究等方面的意义。调查结果显示,河套地区土壤主要富集Mg、Ca等碱性物质,西部狼山一带的多金属矿区应重视Ga、Ge、Tl等分散元素矿床的研究,乌拉山到大青山一带是寻找绿岩型金矿的有利地区。-20目粒级的土壤元素含量反映了河套地区的元素地球化学特征,同时不同成土母质决定了不同的元素富集与贫化特征,狼山山前冲积扇中是一套以多金属及分散元素为主的异常组合。河套地区的城市区内存在Pb、Hg、C、Ag、Au、P、Cd等元素异常的共同特征。古湖泊区与现代乌梁素海均表现F、Mo、U、CaO、MgO、Sr、C、I为正异常、S iO2为负异常的特征。同时现代乌梁素海沉积物中富集有机碳、N、P、Se,pH值较低;古湖泊则相反。河套地区氟中毒区与古湖泊、古河道以及白垩系地层分布范围一致,发病程度与高氟地下水含量呈正比关系。砷中毒与砷的全量和As3+共同作用有关,砷的价态对砷中毒产生影响,As3+含量越高,病况越严重。