火焰原子吸收光谱法分析沉积物中重金属元素的形态

采用原子吸收光谱法研究了金沙江攀枝花段水系沉积物中重金属的形态及分布特征。研究发现,各重金属的形态以残渣态为主,离子交换态含量很少。同时说明原子吸收光谱法完全可以用来研究重金属形态特征,在环境研究中具有重要意义。     

沉积物中重金属形态分析方法研究进展

介绍近年来国内外对沉积物中重金属的研究概况,以及重金属形态分离方法和监测方法的最新进展,对国内外常用的沉积物中重金属的形态分析提取方法如Tessier法、Forstner法和BCR法进行了比较,概述了重金属形态分离检测方法。     

连续萃取法研究海湾养殖区沉积物中重金属形态

以连续萃取法研究海湾养殖区沉积物中重金属(Cd, Cu, Pb, Zn)的形态,将重金属分离为酸溶态、还原态、有机质结合态、硫化物结合态和残渣态.分别采用基体匹配法和内标法消除高盐基体对电感耦合等离子体光谱法(ICP-OES)和质谱法(ICP-MS)分析结果的影响.对海洋沉积物标准物质分析结果表明,样品稀释后测定值与标准值一致.比较了本连续萃取法和BCR法对沉积物样品中重金属形态的提取结果,并考察了萃取剂的选择性.实验表明,本方法可用于有机质污染和富营养化环境沉积物中重金属形态分析,特别是有机质结合态和硫化物结合态的分析.     

微波消解-石墨炉原子吸收法测定沉积物中重金属的全量及形态

优化了微波消解沉积物样品前处理方法,选择了HNO3-HF体系。以沉积物标准物质(GBW07436)为参照对象,选用HNO3-HF微波消解提取重金属全量,采用BCR三步法提取重金属形态,建立了石墨炉原子吸收光谱法(GFAAS)测定As,Cd,Pb,Cr,Cu,Mn,Zn,Ni,Co 9种重金属全量及形态的方法。结果表明,重金属全量测定结果误差为-4.58%~7.33%,BCR形态结果误差为-7.9%~11.6%,符合质控误差范围要求。各重金属形态之和提取率为88.96%~109.36%。对于含多种重金属的沉积物样品,微波消解-GFAAS分析可作为其重金属形态与总量研究的一种分析手段。     

象山港沉积物对重金属Fe和Mn的吸附特征

对象山港不同站点的沉积物对重金属铁、锰的吸附特征进行了研究,考察了阳离子交换量、有机质含量对铁、锰的吸附能力的影响。吸附动力学实验表明,沉积物对铜和锌的吸附量随着铁、锰的初始含量增加而增大,但分别都在40 min和30 min左右达到吸附平衡;热力学实验结果表明,不同沉积物对铁、锰的热力学吸附过程符合Freundlich等温方程,各站点沉积物对铁的吸附能力由强到弱依次是S02,S25,S17,S10,S12,D03,D08,各站点沉积物对锰的吸附能力由强到弱依次是S02,S25,S17,S12,S10,D03,D08;影响因素实验表明,有机质的含量是影响沉积物对重金属铁吸附能力的主要影响因素之一,而沉积物对锰的吸附能力与阳离子交换量存在一定的关联性,有机质的含量几乎不影响沉积物对锰的吸附能力。因此,沉积物对重金属铁、锰的吸附系数K并不与其中单个理化性质有明显的相关性,这说明沉积物对铁、锰的吸附强度受多种沉积物理化性质控制。     

海湾河口表层沉积物中重金属形态连续萃取方法的优化研究

采用单一萃取程序对建立的重金属形态连续萃取方法的萃取条件进行优化.分别以Ca和Mg、Fe、有机质(OM)和酸可挥发性硫(AVS)作为萃取剂释放酸溶态、还原态、有机质结合态和硫化物结合态等重金属目标形态的表征参量,考察萃取剂对相应目标形态的萃取能力和选择性.分别根据表征参量和重金属在萃取溶液中的含量变化确定最优萃取时间和萃取样液比.结果表明,优化萃取条件后,萃取剂对目标形态重金属均有很强的释放能力.酸溶态萃取剂对其它非残留态影响很小;还原态萃取剂除对酸溶态有少量提取外,对其它形态影响较小;有机质结合态萃取剂对硫化物结合态有少量萃取,对其它形态影响较小.硫化物结合态在酸溶态、还原态和有机质结合态之后萃取,避免了对这三种形态的影响.优化后的连续萃取方法对重金属形态有较好的选择性,可对海湾和河口表层沉积物中重金属的目标形态进行较为合理地分离和评价.     

缺氧沉积物中重金属形态连续萃取方法的稳定性研究

考察了海水养殖区域缺氧沉积物中重金属形态连续萃取法萃取过程中溶液pH值、温度变化和胶体形成对形态分离结果的影响。结果表明,连续萃取法Step1萃取酸溶态时,萃取液pH值的轻微升高使Pb和Zn的萃取结果明显降低;Step2萃取还原态时,萃取液pH值明显升高对重金属的萃取结果影响很小;Step3萃取有机质结合态时,萃取液pH值的降低对重金属萃取结果影响较小(除Pb外)。由于连续萃取法中各步萃取反应的热力学过程不同,Step1和Step2萃取后溶液温度轻微升高而在Step3中溶液温度稍微降低,溶液温度变化(<2.5℃)对重金属形态的影响很小。在Step1、Step2和Step4萃取过程中胶体的形成和存在,对萃取液Cd、Zn和Cu有明显的吸附影响;而在Step3萃取中萃取剂的分散作用有效控制了溶液中胶体的形成。因此采用连续萃取方法评价沉积物中的重金属形态时,控制萃取液pH值和胶体形成有利于提高萃取结果的稳定性和准确性。     

表层沉积物(生物膜)非残渣态组分的选择性萃取分离及其吸附铜/锌的特性

采用化学萃取技术对表层沉积物(生物膜)的非残渣态组分(铁、锰氧化物及有机质)进行了分离, 并研究了表层沉积物(生物膜)非残渣态和残渣态组分吸附铜、锌的特性. 结果表明, 0.1 mol/L NH2OH·HCl+0.1 mol/L HNO3, (NH4)2C2O4-H2C2O4缓冲溶液和体积分数为30%的H2O2可选择性地萃取分离表层沉积物(生物膜)非残渣态的锰氧化物、铁锰氧化物和有机质, 萃取率为63.15%～97.59%, 同时对非目的组分影响较小; 表层沉积物(生物膜)及其各组分对铜的吸附能力均大于对锌的吸附能力, 且生物膜及其各组分对铜、锌的吸附能力均高于表层沉积物及其相应组分对铜、锌的吸附能力; 表层沉积物(生物膜)非残渣态组分对铜、锌的吸附能力均大于残渣态组分, 且非残渣态组分中锰氧化物的单位吸附能力最强, 其次是铁氧化物, 而有机质的单位吸附能力较弱, 比锰氧化物低2个数量级, 说明生物膜对水体中痕量重金属的迁移转化作用强于表层沉积物, 而表层沉积物(生物膜)中金属(铁、锰)氧化物对水中痕量重金属起主要控制作用.     

胶州湾表层沉积物重金属分布特征及污染评价

为评价胶州湾跨海大桥的建设对其沉积物中重金属分布的影响,于2009年7月采集了黄海胶州湾11个站位的表层沉积物,测定了沉积物中的重金属含量.结果显示,胶州湾沉积物重金属污染程度较低,Hg、Cu、Pb、Zn、Cd、Ni、Co、Mn 8种重金属的平均含量分别为0.031、19.05、12.7、51.14、0.055、17....     

大气颗粒物重金属形态分析

重金属作为大气颗粒物中重要有毒组分之一,其总量和存在形态与颗粒物重金属的健康风险密切相关。因此,颗粒物重金属形态分析对深入研究大气污染健康效应具有非常重要的意义。本文从以下四个方面对近年来国内外相关研究进行了归纳总结:(1)模拟体液、BCR、Tessier、Chester等逐级顺序提取方法被广泛用于重金属操作定义形态分析;(2)色谱-质谱联用技术和新型功能化材料用于重金属形态选择分析以及X射线吸收精细结构谱(XAFS)原位形态表征技术可以获取重金属价态、化合态、原子簇结构信息;(3)重金属形态粒径分布特征复杂,受多种因素影响,倾向于富集在细颗粒物中;(4)重金属形态时空分布具有很强的区域性,社会发展、工业来源、气候条件是主要影响因素,夏冬季节和雾霾天气危害性较大。     

Distribution and speciation of metals in surface sediments of Taranto [corrected] gulf (Ionian Sea, Southern Italy)

Concentrations of metals (Al, Fe, Ti, Ni, Mn, Cr, Zn, Cu, Pb) were determined in surface sediments from Taranto gulf (Ionian Sea, Southern Italy) in order to assess the distribution and the bioavailability of metals. Total metal content and speciation of Fe, Ni, Mn, Zn, Cu and Pb were determined. Sediment cores were also sampled in some stations of particular interest. The analytical results show that metals distribution does not show significant variations in relation to depth. Metal distribution in the Taranto gulf is mainly influenced by industrial wastes from Taranto town, by rivers of the Basilicata region and by prevailing anticlockwise marine currents. These factors cause an accumulation of metals in the sediments near to the coasts of Calabria. The statistical analysis, effected by HCA and PCA methods, can be considered a good starting point in order to classify sediment samples and to locate accumulation areas. Metal speciation shows that Fe, Ni and Zn are present in sediments mainly as sulphides, Mn is present principally in an ion-exchange form or bound to carbonate, while Cu and Pb are mainly present in the fraction bounds to humic acids.     

煎煮对几种特色南药中重金属元素含量和形态影响

考察了几种特色南药中重金属(Cd,Cr,Cu,Fe,Mn,Ni,Pb,Sr,Zn)的含量状况,并采用形态连续萃取法分析重金属在药材中的形态分布,研究了药材煎煮时药材中重金属的释放及煎煮过程对药材中重金属形态分布的影响。结果表明,几种南药中Cr,Pb,Zn的含量较高,且巴戟天中的重金属总量高于限量标准;原药材中Cr,Cu,Mn,Ni,Pb和Zn主要存在于有机态和残留态,Fe和Sr主要存在于残留态。煎煮使南药中大量重金属迁移到药汤中;药汤中Cu,Mn,Cr,Pb和Zn主要来自于其在药材中的可交换态、碳酸盐结合态和有机态,而药汤中Sr,Ni和Fe不仅包含其非残留态,更多来自于它们的残留态。为减少药汤中重金属,对于Cu,Mn,Cr,Pb和Zn既要控制在药材中的总量,且需降低它们在药材中的非残留态含量;对于Fe,Ni和Sr则主要是控制其在药材中的总量。     

耐高盐碱蓬对湿地土壤中金属元素的富集特征研究

基于秦皇岛滨海湿地人工种植耐高盐碱蓬修复工程试验,通过分析湿地土壤沉积物及耐高盐碱蓬中不同金属元素的含量与变化,研究了耐高盐碱蓬对金属元素的富集特征。结果显示:湿地沉积物中Fe、Mn、Cr、Pb和Zn的浓度较高,分别为8 210. 94、110. 04、8. 78、8. 25、10. 95 mg/kg,Cd的浓度最低,平均值为0. 022 mg/kg,湿地试验区土壤中同一金属元素变异程度较小,分布较均匀。碱蓬体内重金属含量根据采集地点的不同有差异,但与各站位中土壤的重金属分布特征存在正相关性;其中碱蓬内Fe、Mn、Zn、Cu的平均含量相对较高,且Fe、Mn、Ni、Cu、As、Cd、Pb元素在碱蓬根中的平均含量高于茎叶,而Cr在茎中的平均含量最高,Zn和Mo在叶中的含量最高。碱蓬的根、茎、叶对Cd的富集效果最好,其次为Mo、Cu,对Fe、Mn、Zn、As和Pb的富集效果相对较差,说明碱蓬对沉积物中不同金属元素的富集移出率存在差异。金属元素在碱蓬中的转移系数研究表明,Mo、Zn、Cd和Mn等元素可由根部转移到叶中,而Fe、Ni、Pb、As和Cu等金属元素固定在根部,该研究可为利用碱蓬修复湿地重金属污染提供理论基础。     

Heavy-metal distribution in river waters and sediments around a "firefly village", Shikoku, Japan: application of multivariate analysis.

River water and sediment samples were collected at the same site in a vicinity of an abandoned mine, and the concentrations of major elements and heavy metals were determined. The chemical correlations were observed by principal component analysis (PCA), and the samples were classified by cluster analysis (CA) based on the PCA scores. The PCA results presented a macroscopic viewpoint of covariance structure, i.e., the chemical elements could be classified into three groups: 1) major elements and heavy metals in the river water, 2) Cd, Fe and Mn in the sediments, and 3) Cu and Zn in the sediments. The CA results implied a similarity of chemical compositions in most parts of the study area, except the ranges close to the abandoned copper mine. At the mixing location of mining water with natural river water, major elements and cadmium showed simple physical mixing (conservative mixing). Other heavy metals (Cu, Fe, Mn and Zn) showed the massive precipitation at the mixing event. The PCA structure was mainly interpreted in terms of the mixing process between mining water and diluted natural river water.     

Distribution of heavy metals of agricultural soils of central Greece using the modified BCR sequential extraction method

The state of heavy metal (Cd, Cu, Ni, Zn, Pb, and Cr) pollution was studied, in 440 texturally different soil profiles in Thessaly, an intensely cultivated region in Central Greece. The study was carried out in 2004 and 2005 on 220 soil samples for each year. Soil samples were classified in three soil orders: Endisols, Alfisols, and Vertisols according to the Soil Taxonomy System. The pseudo-total concentrations of heavy metals were determined by the aqua regia procedure. Heavy metals were also determined after division into four fractions by sequential extraction with (a) acetic acid (exchangeable and specifically adsorbed metals), (b) a reducing agent (bound to Fe/Mn hydroxides), (c) an oxidizing agent (bound to soil organic matter), and (d) aqua regia (bound to mineral structures, residual). The concentrations of all the metals studied were higher in the topsoil (0–30?cm) and lower in the second soil layer (30–60?cm). Concentrations of 70–82% of Cd, 39–64% of Cu, 41–69% of Ni, 29–51% of Zn, 75–89% of Pb, and 52–87% of Cr were found in the first two fractions. Cd appeared to be the most mobile of the metals studied, while Cu and Zn were found in forms associated with soil organic matter. The chemical partitioning patterns of Pb and Cr indicated that these metals are largely associated with the Fe–Mn hydroxides, while Cr was also found in the residual fractions. Significant correlations between heavy metals fractions and soil physicochemical parameters were obtained and discussed.     

Analysis of heavy metals in road-deposited sediments

Road-deposited sediments were analysed for heavy metal concentrations at three different landuses (residential, industrial, commercial) in Queensland State, Australia. The sediments were collected using a domestic vacuum cleaner which was proven to be highly efficient in collecting sub-micron particles. Five particle sizes were analysed separately for eight heavy metal elements (Zn, Fe, Pb, Cd, Cu, Cr, Al and Mn). At all sites, the maximum concentration of the heavy metals occurred in the 0.45-75 μm particle size range, which conventional street cleaning services do not remove efficiently. Multicriteria decision making methods (MCDM), PROMETHEE and GAIA, were employed in the data analysis. PROMETHEE, a non-parametric ranking analysis procedure, was used to rank the metal contents of the sediments sampled at each site. The most polluted site and particle size range were the industrial site and the 0.45-75 μm range, respectively. Although the industrial site displayed the highest metal concentrations, the highest heavy metal loading coincided with the highest sediment load, which occurred at the commercial site. GAIA, a special form of principal component analysis, was applied to determine correlations between the heavy metals and particle size ranges and also to assess possible correlation with total organic carbon (TOC). The GAIA-planes revealed that irrespective of the site, most of the heavy metals are adsorbed to sediments below 150 μm. A weak correlation was found between Zn, Mn and TOC at the commercial site. This could lead to higher bioavailability of these metals through complexation reactions with the organic species in the sediments.     

Characterization of Metals in Surface Sediments from Xiaoyang River,Jiangsu, China

Some metal species and fractions have high affinity to anthropogenic activities, making it feasible to characterize the spatiotemporal characteristics of human-induced degradation of ecosystems. The accumulation of Fe, Mg, Mn, Zn, Cu, Cr, Ni, and Pb, their fractions, physiochemical parameters, and nutrients was evaluated in the surface sediments at 11 sites on the Xiaoyang River in urban and suburban locations in Jiangsu, China for the assessment of pollution. The sediment quality was evaluated based on sediment quality guidelines, enrichment factors, geoaccumulation index, potential ecological risk index, and risk assessment code. Principal component analysis and cluster analysis were used to identify the sources of the metals. The total concentrations of metals, enrichment factors, and geoaccumulation indices demonstrated that all sites were significantly polluted with Zn and significantly to moderately polluted by Cu, Pb, and Ni. Moreover, higher metal enrichment was present downstream through downtown Sheyang due to extensive human activities. However, the potential ecological risk indices and risk assessment codes revealed high bioavailability and toxicity of Pb in this region. These results indicated that the metal fraction showed higher susceptibility. The accuracy of the ecological risk assessment was evaluated in the river, indicating a heavy anthropogenic impact.     

Speciation of heavy metals in sediments of the lagoon of Venice collected in the industrial area

In this study a procedure of sequential extraction of metals from sediments was applied to samples from the lagoon of Venice. Compared to the measurement of total concentrations, the knowledge of metal partitioning among sediment phases can help in estimating the risk posed by metal polluted sediments and give information on contamination sources and on the factors that influence metal enrichment in sediments. The results permitted to estimate for each metal the percentage of the total content that could be potentially remobilized from sediments, owing to changes in environmental conditions. The immediately available fraction represented in general a low proportion of the total content. An important proportion of most metals (except for Zn, Cd and Cu) was associated to residual phases and therefore was not expected to be released under the normal environmental conditions. The large amounts of metals bound to Fe-Mn oxides/hydroxides confirmed the strong scavenging efficiency of this phase. The carbonate phase was the preferential associative form for Pb, Cd and Zn, whereas Cu was bound in prevalence to the organic matter/sulphide phase.     

Ecological risk assessment of sediment in wastewater discharging area by means of metal speciation

This study was designed to evaluate the influence of wastewater discharge to the marine ecosystem after treatment plant construction. Heavy metal concentrations in sediment and bioavailability of the metals were analyzed and ecological risks were assessed using the results. Metal speciation for sediments collected in the wastewater discharging area was measured by a Shimadzu AA-680 atomic absorption spectrometer. The distribution of the metals among various geochemical phases was determined. Biological samples collected and analyzed were four species of crustacea, four species of bivalve, and seven species of fish. Exchangeable fraction of superficial sediment (0–2 cm layer) was Zn 35.09%, Ph 5.30%, Cu 0.86%, Cr 0.01% and Fe 0%. However, exchangeable fraction of deep layer sediment (15–20 cm) was not detected for all metals analyzed. Deeper sediments were found to have more residual fraction, and bioavailable phases decreased by depth, which provides an indication of the seriousness of wastewater discharge effect in this enclosed bay. The chemical concentrations observed to be associated with biological effects were sorted. The comparisons were made with regard to the potential for adverse biological effects. The potential of adverse biological effects in the sediments of wastewater discharge site was estimated as Zn 69.8%, Pb 35.8%, Cu 29.1%, and Cr 21.1%, respectively. Mullet (Mugil cephalus) among biological samples had the highest concentration of Zn in the muscle and liver organs. The bioconcentration factors (BCFs) of Zn by the mullet, mussel, oyster and crab were the highest among heavy metals determined. This result was well related to 81.6% of bioavailable phase Zn and 69.8% of adverse biological effects for the surface sediment.