土壤中重金属元素电感耦合等离子体质谱定量分析方法的研究

分别采用HNO3-HF、HNO3-HF-HCl和HNO3-HF-H2O2三种消解体系,通过微波和PTFE密封罐电热板对土壤标准物质进行前处理,采用电感耦合等离子体质谱(ICP-MS)对样品中的重金属元素Cr、Ni、Cu、Zn、As、Cd和Pb进行定量分析。探讨了前处理试剂(主要为HNO3、HCl和HF)以及土壤基体效应对Cr、Ni、Cu、Zn、As、Cd和Pb定量分析的影响。研究结果表明,前处理试剂对Cr、Ni、Cu、Zn、As、Cd和Pb的定量分析具有不同程度的影响;对于土壤基体,在三种消解体系下均可观察到基体抑制效应;采用PTFE密封罐电热板消解方法前处理,待测元素及相同元素不同同位素的方法空白和检出限均较低,效果整体优于微波消解法。特别是HNO3-HF-HCl消解体系,通过选用52Cr、60Ni、65Cu、66Zn、75As和206Pb等同位素,重金属元素Cr、Ni、Cu、Zn、As、Cd和Pb的测定值均能保证在标准值的允许误差范围内,可以满足大批量土壤样品中重金属元素同时定量分析的需要,为高效准确地开展土壤的风险评估以及为土壤的修复治理提供科学依据。     

土壤—作物系统中重金属元素的地球化学行为

对我国部分土壤和作物中重金属元素的分布特征作了概括性的论述，指出重金属元素的富集或贫化与成土母质、土壤环境等因素密切相关。母质母岩中元素含量高则相应土壤中该元素富集；土壤偏碱性或氧化条件下，重金属元素的有效性低；重金属元素通常富集于土壤表层0-20cm层位。不同种类的粮食、蔬菜对土壤中重金属元素具有不同程度的吸收和富集能力，叶类菜比茎类菜对重金属具有更强的吸收和富集能力，粮食作物的根比籽粒含重金属更多。对已污染的土壤大多采用生物修复和生态修复方法。     

北京平原区两年内土壤中五种重金属元素化学形态变化及生物有效性

为了监测北京市平原区2015年和2016年土壤中5种重金属As、Cd、Hg、Pb、Zn化学形态的变化趋势,运用Tessier连续提取法对土壤重金属进行了形态分析,并对影响重金属元素生物有效性的因素进行研究。结果表明,2年内研究区表层土壤重金属元素的形态变化微弱,有效态含量以Cd元素最高,达到45.67%,故潜在生态危害性最大;其次为Zn元素,达12.16%,其中碳酸盐结合态占比虽大,但由于研究区土壤呈偏碱性,Zn元素的迁移能力较弱,潜在危害性较小;As、Hg、Pb均以难迁移态存在,故潜在危害性也较小。土壤重金属元素的生物活性系数及迁移系数分别为:CdZnPbAsHg和CdAsZnPb=Hg,其中Cd元素2年的生物活性系数和迁移系数最高,展现出较强的生物活性和迁移能力,其余重金属元素的活性系数和迁移系数较低,潜在危害性较弱。影响重金属元素生物有效性的因素较复杂,以重金属元素全量为主,p H、有机质、CEC等理化性质次之。     

平阴县土壤中重金属元素异常成因研究

通过对平阴县周边及其西部农田区采样调查,平阴县周边元素异常具有异常衬度较高,富集系数大等特征,西部农田区异常具有各元素套合关系好,多数异常衬度不高,富集系数小的特点。结果表明,西部农田区异常是以As,Cd为主要成分的异常,元素含量与SiO2,Al2O3,Fe2O3等常量组分间具有显著的相关性,随SiO2含量的增加而降低,随Al2O3,Fe2O3含量的增加而增加,说明土壤常量组分及其所决定的土壤质地是导致异常形成的主要因素;而平阴城区异常是以S,Hg,As,Zn,Mn等元素为主的异常,是典型的人为综合因素（化工烟尘、工厂污水、生活垃圾）产生的异常。     

山东省平阴县土壤中重金属元素异常成因

为改善平阴县生态环境,为农业区划、环境保护和地方病防治等领域提供全新的地球化学资料和科学依据,开展了平阴县生态地球化学调查。调查发现,平阴县周边及其西部农田区有As、N i、Cd、Cr、F、Cu、Mn、S、Hg等以重金属为主的元素异常,平阴县周边元素异常具有异常衬度较高、富集系数大等特征,西部农田区异常具有各元素套合关系好、多数异常衬度不高、富集系数小的特点。研究结果表明,西部农田区异常以As、Cd为主要成分,元素含量与S iO2,A l2O3,Fe2O3等常量组分间具有显著的相关性,随S iO2含量的增加而降低,随A l2O3,Fe2O3含量的增加而增加,说明土壤常量组分及其所决定的土壤质地是导致异常形成的主要因素;而平阴城区异常以S、Hg、As、Zn、Mn等元素为主,是典型的受人类综合污染而产生的异常。     

长寿地区土壤重金属元素污染特征及评价

为查明长寿城区及周边区域表层土壤中As、Cd、Hg等8个重金属元素的污染情况,进行土壤测量结果显示,区内Cr、Hg、Ni等大部分元素的平均含量高于三峡库区深层土壤背景值,Hg、Pb的后期叠加作用最为强烈;除Hg外,其余7个元素含量间存在显著正相关,其中Cr、Ni最为显著;随着p H值增加,Ni、Cr、Cd、Cu含量显著增加;单因子污染指数评价和内梅罗综合指数评价均显示研究区内土壤环境质量总体较好,污染区域较少,以轻度污染-中度污染为主,重污染约占全区面积的0.3%,Hg元素为研究区内最主要的污染元素。     

磷石膏堆周围农田土壤中重金属元素形态研究及评价

磷石膏在自然堆放过程中,由于淋滤、风化等作用,一些重金属元素进入土壤后会对周围土壤造成污染。土壤一旦遭受重金属的污染,一般很难消除,进入土壤的重金属具有滞后性、隐蔽性和长期性,使堆放点周围土壤重金属污染愈来愈严重。重金属通过溶解、沉淀、凝聚、络合、吸附等各种反应,形成不同的化学形态,最终通过     

烟台市土壤环境质量现状及重金属元素分布迁移规律

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,发现土壤主要污染因子是Cd、As、Hg、Cu、Pb、Zn等重金属元素,工矿三废排放是土壤重金属的主要来源;过量施用化肥和工矿污染形成的酸雨使区内土壤明显酸化,土壤根系土中镉等元素在酸性环境中活化迁移能力明显增强,有毒重金属镉等通过土壤-水-植物活化迁移量大,经食物链向人体中转移危险性增大。土壤重金属污染和土壤酸化成为烟台市域内两项重大的生态环境问题,为土地污染防治提供了科学依据。     

土壤中重金属元素Pb、Cd地球化学行为影响因素研究

通过研究湖南洞庭湖地区水稻土中Pb、Cd与土壤有机质、粘粒和pH值的关系,结果表明,(1)土壤中有机质含量与Cd、Pb有着显著的正相关性,土壤中有机质含量增加可明显降低Cd和Pb的离子态和可交换态含量。(2)随着粘粒含量增加,Pb和Cd离子可交换态占全量的比值略有增加,这说明粘粒表面吸附的Pb和Cd容易进入植物体中,对生态系统安全具有危害的组分。(3)Cd离子交换态与土壤pH值呈显著相关关系,土壤酸化使Cd的离子交换态比例上升,可直接导致农作物中Cd含量增加,防止土壤酸化是控制Cd对生态系统危害的有效途径;Pb的离子交换态与全量的比值与pH值具有显著的相关性,对于Pb污染严重的土壤,保持土壤pH值在弱酸性至弱碱性范围,防止土壤酸化和盐碱化,可以降低Pb危害。土壤有机质含量、pH值等是控制重金属元素地球化学行为的重要因素之一。     

合肥市土壤重金属元素异常及其生态效应

通过对合肥市及其周边地区表层土壤重金属元素异常空间分布特征的分析，查明了生活和工业排污是形成Hg、Cd、Pb、Zn异常的主要原因；相对于深层土壤，表层土壤具有明显的富集特征，自地表向下重金属元素含量呈迅速下降趋势。探讨了土壤重金属元素全量与有效量、土壤pH值的关系，土壤重金属元素有效度大小排序为：Cd〉Pb〉Zn〉Hg，Cd、Pb有效量与全量相关性显著，且与pH值呈负相关，随着土壤cd、Pb元素全量的增加以及土壤不断酸化，其生态风险将显著增大。异常区土壤重金属的累积已造成部分蔬菜重金属超标，进而影响到蔬菜食用安全性，因此，加强土壤环境质量保护，对保证合肥市社会经济可持续发展具有重要意义。     

土壤粒级中重金属元素的形态分析与环境风险评价

研究评价不同粒级组分中重金属的活性和潜在环境风险,对3个地区土壤颗粒的分析表明,重金属在土壤中分布并不均匀,随着颗粒粒径的减小,重金属Cu、Cd元素及有机质的浓度有不断增高的趋势。线性分析显示,Cu、Cd元素浓度与有机质的浓度显著相关。形态分析表明,Cd主要以环境高活性的形态存在,其次以低活性的形态存在,环境惰性的形态仅占极小部分,Cu主要以低环境活性和环境惰性的形态存在,高环境活性的形态只占小量,Cu在土壤中的存在形态可能与土壤性质有关。     

Comparison of different methods for assessing heavy metal contamination in street dust of Xianyang City, NW China

Street dust is one of the important indicators that reflect the status of urban environmental pollution. There are many studies of heavy metals contamination of street dust in capital cities; however, little attention has been paid to this kind of study in medium cities, including China. The dust samples were collected in the district of traffic crossroads in Xianyang city, Shaanxi Province. Pb, Cd, Cu, Ni, Zn, Cr and Mn concentrations were determined using atomic absorption spectrometry (AAS). The results indicate that the concentrations of heavy metals are higher than the background values of soils in Shaanxi Province. The contamination level of heavy metals is assessed by potential ecological risk index (E _r), geoaccumulation index (I _geo), enrichment factor (EF) and pollution index (Pi). The low I _geo, EF, E _r, Pi and PI_n (integrated pollution index) for Mn in street dusts indicate an absence of distinct Mn pollution. The high EF, Pi and PI_n of Cu and Zn indicate that there is considerable Cu and Zn pollution. It is suggested that more attention should be paid to heavy metals contamination of Cu and Zn. The assessment results of Pi and PI_n suggest that Pb, Ni and Cr present strong pollution; however, their EFs indicate that they cause moderate pollution and their I _geo indicates that they are unpolluted to moderately polluted. The contamination class value with different assessing methods is of the order: Pi ≈ PI_n > EF > I _geo > E _r.     

江西鄱阳湖地区不同酸度土壤的重金属元素和有益元素化学形态分布特征研究

通过对江西省鄱阳湖地区樟树-奉新、抚州-九江以及东乡-彭泽三条生态大剖面的表层土壤和农作物根系土的采集和土壤pH值、9个重金属元素全量和化学形态含量、13个营养有益元素有效态含量的分析测试,获得了极为丰富的数据,进而分析研究了土壤中重金属元素形态分布特征、全量与形态含量的相关性、形态随土壤pH变化规律,并提出了防治土壤酸化及其负效应的建议.     

土壤中重金属形态分析方法研究

介绍了一种重金属形态分析连续多级提取新方法,用国家一级标样进行试验研究,并用国际标样做对比研究,表明该方法具有分组合理、更接近自然状态、操作简便易行、数据稳定可靠的特点,可为土壤环境中的重金属形态的研究及其环境危险评价提供更精确的元素信息。     

Characterization of heavy metal contaminated soils in Northern Cyprus

The Lefke region of Northern Cyprus was a site of intense copper mining and smelting activities until the 1970s, which produced large tailings. This study was initiated to characterize the heavy metal contamination of soils of the area and to assess the influence of this site on the surface seawater quality along the coastline. Soil and seawater samples were collected and analysed. Copper and arsenic concentrations exceeded the limits for 'extremely polluted' soils for some samples, which can be classified as 'polluted' by zinc, cadmium and lead. The results showed that seawater was seriously polluted by chromium, nickel and copper in the vicinity of the smelting facility. Copper and iron concentrations increased tenfold after rainfall (wet period), indicating the contribution of tailings to marine pollution. There is an urgent need for remediation treatment for the site.     

加筋土不同计算方法之间的关系

加筋土中筋材与土的关系与钢筋混凝土中钢筋与混凝土的关系类似。两者的计算方法也具有相似性。等效附加应力法根据附加节点力计算方法的不同分别对应整体式和组合式方法。钢筋混凝土中经典的整体式和组合式方法构成了等效附加应力法的理论基础。反过来,从等效附加应力的角度分析,虽然分离式、整体式、组合式3种方法的单元刚度矩阵不同,但在本质上其实是一致的,区别主要在于边界上等效附加节点力的分配有所不同。（整体式和分离式可看作是特殊的组合式。）等效附加应力法的思想揭示了3种方法内在的处理原理,并且能够用于解释3种方法计算结果异同的原因。借鉴接触面的研究成果,选择合适的应变比例系数计算方法,也能在整体式和组合式方法中考虑筋材和土的滑移情况     

Comparative analysis of heavy metal concentration in secondary treated wastewater irrigated soils cultivated by different crops

The use of treated urban wastewater for irrigation is a relatively recent innovation in Botswana and knowledge is still limited on its impact on soil heavy metal levels. The aim of this study is to analyze and compare heavy metal concentration in secondary wastewater irrigated soils being cultivated to different crops: olive, maize, spinach and tomato in the Glen Valley near Gaborone City, Botswana. The studied crop plots have been cultivated continuously under treated wastewater irrigation for at least 3 years. Most crop farms have sandy loam, loamy sand soils. Based on food and agriculture organization, heavy metal threshold values for crop production have been studied. Results showed that the wastewater irrigated soils in the Glen Valley have higher cadmium, nickel and copper than desirable levels, while the levels of mercury, lead and zinc are lower than the maximum threshold values recommended for crop production. The control sites show that the soils are naturally high in some of these heavy metals (e.g copper, zinc, nickel) and that crop cultivation under wastewater irrigation has actually lowered the heavy metal content. Comparing between the crops, mercury and cadmium levels are highest in soils under maize and decline linearly from maize to spinach to olive to tomato and control site. By contrast, concentrations of the other metals are at their lowest in maize and then increase from maize to spinach to olive to tomato and to control site.     

地质样品中铂族元素的分析测定方法

文中阐述并归纳了近年地质样品中铂族元素的分离、富集及测试方法方面的最新进展。铂族元素本身的超痕量性,要求实验过程中对空白值的控制,干扰元素的扣除和检测限的降低更为严格,同时要克服块金效应。文中对消解过程中常用的火试金法、酸溶、碱熔方法和卡洛斯管法(Carius tube),分离富集过程中的Te共沉淀和离子交换法,测试手段中的原子光谱法、中子活化法和等离子质谱法等方法的最新进展进行了总结。由于复杂的地质样品中PGE的浓度范围不一、赋存形式多样,要求在具体样品分析过程中灵活地搭配使用各种分离富集和检测方法,结合笔者所在实验室在实验过程中发现的问题,对各种不同类型地质样品中铂族元素的分离富集、样品处理及测定方法也进行了总结。     

珠江三角洲潜在生态风险:土壤重金属活化

珠江三角洲典型土壤模拟酸雨提取实验表明，土壤酸缓冲能力为菜园土大于水稻土大于赤红壤。酸化过程早期，铝铁胶体吸附共沉淀导致重金属溶出量增长不明显甚至下降；进一步酸化时，多数元素溶出量与加入酸量呈显著正相关。计算表明，在pH=4．5的酸雨作用下，溶液中Hg、Mn、Pb、Fe(以Fe2O3表示)浓度已超出Ⅱ级地表水标准，Cu、Zn大大高于渔业用水标准。可见，土壤元素活化溶出对水体生态环境有潜在的危害。     

Utilization of fly ash for stabilization/solidification of heavy metal contaminated soils

Pozzolanic-based stabilization/solidification (S/S) is an effective, yet economic remediation technology to immobilize heavy metals in contaminated soils and sludges. In the present study, fly ash waste materials were used along with quicklime (CaO) to immobilize lead, trivalent and hexavalent chromium present in artificially contaminated clayey sand soils. The degree of heavy metal immobilization was evaluated using the Toxicity Characteristic Leaching Procedure (TCLP) as well as controlled extraction experiments. These leaching test results along with X-ray diffraction (XRD), scanning electron microscope and energy dispersive X-ray (SEM–EDX) analyses were also implemented to elucidate the mechanisms responsible for immobilization of the heavy metals under study. Finally, the reusability of the stabilized waste forms in construction applications was also investigated by performing unconfined compressive strength and swell tests. The experimental results suggest that the controlling mechanism for both lead and hexavalent chromium immobilization is surface adsorption, whereas for trivalent chromium it is hydroxide precipitation. Addition of quicklime and fly ash to the contaminated soils effectively reduced heavy metal leachability well below the nonhazardous regulatory limits. Overall, fly ash addition increases the immobilization pH region for all heavy metals tested, and significantly improves the stress-strain properties of the treated solids, thus allowing their reuse as readily available construction materials. The only potential problem associated with this quicklime–fly ash treatment is the excessive formation of the pozzolanic product ettringite in the presence of sulfates. Ettringite, when brought in contact with water, may cause significant swelling and subsequent deterioration of the stabilized matrix. Addition of minimum amounts of barium hydroxide was shown to effectively eliminate ettringite formation. Overall, due to the presence of very high levels of heavy metal contamination along with sulfates in the solid matrices under study, the results presented herein can be applied to the management of incinerator and coal fly ash, boiler slag and flue gas desulfurization wastes.