兰坪金顶铅锌矿区土壤重金属Zn、Cd分布特征研究

通过连续提取法测定兰坪金顶铅锌区土壤中Zn、Cd的形态含量,笔者等分析了污染物的分布、化学形态的变化。结果表明,金顶矿区土壤中Zn、Cd总量大范围超标,Zn的水溶态含量为n·100μg/g,离子交换态为n·10μg/g,残渣态、活性铁锰态、碳酸盐态和有机结合态含量为n·102μg/g,Cd的水溶态含量为n·10-2μg/g,其他各态基本在同一数量级为n·100μg/g,部分地区Zn离子交换态含量超过国家土壤环境质量标准（Ⅲ级）中总量标准1倍以上,而Cd离子交换态含量平均是Ⅲ级总量标准的5倍,Cd污染要更加严重。污染及形态分布受矿体展布、地形、矿业活动、地表径流等的影响。Zn、Cd的环境有效态（水溶态、离子交换态与碳酸盐态之和）含量比较高,对兰坪矿区及沘江流域具有潜在的危害。     

德兴矿区土壤中铜的地球化学形态及影响因素

土壤中铜的地球化学形态决定了其在环境中的释放、变化形式、迁移规律及生物效应。通过对德兴铜矿及周边地区82件表层土壤样品,采用改进的BCR提取方法测定铜的地球化学形态,了解其区域分布特征,结果表明:(1)德兴地区土壤中酸可溶态的铜≈可还原态铜<可氧化态铜≈残渣态铜,酸可溶态 可氧化态 可还原态的铜平均质量分数为45.07×10-6,较中国土壤背景值全铜的质量分数(22.6×10-6)高,这些活动态的铜易于进入食物链,对人体健康和生态安全构成潜在的威胁,不同形态铜的区域分布特征相似,主要位于采矿和选矿活动区附近;(2)采用改进的BCR方法提取的土壤中铜的酸可溶态和可氧化态和采用EDTA提取的可交换态具有明显的正相关关系,土壤pH值增大时酸可溶态铜的比例降低,土壤TOC含量增加时可氧化态铜的比例增大,而土壤CEC对BCR方法提取铜的形态影响不大。     

云南兰坪金顶铅锌矿区土壤中Pb分布特征

采用连续提取法测定兰坪金顶铅锌矿区土壤中Pb的形态含量,通过地统计方法分析污染物的空间分布、化学形态变化特征,结果表明金顶矿区土壤中Pb大范围严重超标,按照国家土壤环境质量标准(Ⅲ级),Pb的中位值超标1.77倍,平均值超标约19倍。插值分布图显示Pb的污染及形态分布受矿体空间展布、地形变化、矿业活动、地表径流等的影响,其中水溶态Pb受植被和水系影响更大。土壤中Pb形态含量依次为残渣态>碳酸盐态>活性铁锰态>有机结合态>离子交换态>水溶态,环境有效态(水溶态、离子交换态与碳酸盐态之和)含量比较高,对兰坪矿区及沘江流域具有潜在的巨大危害     

土壤样品中镉的形态分析研究

采用改进的Tessier连续提取法对武汉地区的土壤样品中镉的形态进行了分析,结果表明土壤中镉主要以离子交换态形式存在,总体看其顺序为离子交换态(包含水溶态)>碳酸盐结合态>铁锰氧化物结合态>腐殖酸结合态>残渣态>强有机结合态,说明土壤中镉较活泼,易于迁移转化,对植物的可给性大,是环境中的重要污染元素.     

山东沂南土壤-植物系统中硒生物有效性评价

为评价山东沂南富硒土壤中的硒在不同作物中的生物有效性并推测其来源,对研究区的土壤、植物和岩石样品进行对应采集,采用ICP-MS等测试了各样品硒元素的总质量分数和水溶态、弱酸提取态、可还原态、可氧化态、残渣态5种形态分量的质量分数,并对结果进行对比分析。结果表明：土壤硒总质量分数受空间位置及水系约束明显;有效硒质量分数与硒总质量分数正相关,空间分布一致;土壤硒总质量分数与氮、磷质量分数正相关;土壤中硒的存在形态以亚硒酸盐为主。研究区富硒土壤上生长的花生、西瓜和核桃3种作物果实中硒元素富集;富硒土壤中硒的来源与区域地层中页岩、泥岩及上游铁矿相关,推测上述岩石经风化成土及后期水流搬运至黏土及砂质黏土区域被土壤黏土吸附沉积形成富硒区。     

城乡交错区土壤中镉的赋存形态及其生物有效性研究

采用连续形态分析方法研究了重庆市城乡交错区土壤中Cd的形态分布及其与莴笋吸收Cd量的关系.结果表明,研究区土壤和莴笋中Cd污染严重,土壤各形态Cd总体分布特征为:残渣态Cd＞有机质结合态Cd＞离子交换态Cd＞碳酸盐结合态Cd＞铁锰氧化物结合态Cd＞水溶态Cd,其中活性较强的交换态Cd(包括水溶态Cd和离子交换态Cd)比重较大.Cd在土壤中的分布与土壤中的物理性粘粒及粉粒含量密切相关.而在土壤各形态Cd中,离子交换态Cd具有较高的生物有效性.研究区土壤和蔬菜中Cd污染已经较严重,建议加强城乡交错区的环境综合管理.     

金昌市铜镍矿区周围土壤中重金属的迁移特征

对金昌矿区不同区域土壤5~20 cm层中重金属各化学形态及活性态的迁移行为进行了研究,结果表明：土壤中重金属不同化学形态迁移率不同,弱酸提取态、可还原态、可氧化态和残渣态平均迁移率分别为0.13、0.51、0.30和0.54。重金属总量和活性态（包括弱酸提取态、可还原态、可氧化态）迁移率也表现出很大差异,尾矿区土壤Cr总量迁移率较高为0.65,而其活性态迁移率较低为0.26,Ni与Cr迁移特征完全相反,总量迁移率为0.26,而活性态迁移率为0.67;农田土壤中Pb总量迁移率低而活性态迁移率高,Ni与Zn特征相似,总量迁移率高而活性态迁移率相对较低;大棚地土壤中重金属迁移率均较低,Cu和Ni活性态几乎未发生向下迁移。可见,重金属的迁移与其化学形态分布关系密切,与重金属总量的迁移率相比,活性态迁移率能够更有效地反映出土壤中重金属的迁移特征和潜在危害性。     

大型金属矿山不同环境介质中重金属元素化学形态分布特征——以甘肃金昌市和白银市为例

重金属元素在环境介质中的存在形态及各形态比例是决定其迁移性和生物可利用性的重要因素.采用BCR法连续提取过程对大型金属矿山周围土壤和水体沉积物中Cd、Cr、Cu、Ni、Pb和Zn化学形态的分析结果表明,土壤和水体沉积物中不同重金属元素化学形态分布有很大差异.总体而言,Cd以弱酸提取态为主(约占60%),Cr以残渣态为主,占90%以上,Cu以可氧化态为主(约占60%),Ni和Pb以可还原态为主,分别约占50%和60%,Zn以残渣态为主,约占45%.不同区域土壤中重金属元素各形态质量分数之和依次为厂区外围>尾矿坝旁>农田,各形态分布也与总量具有相似的变化趋势.金昌市矿山环境介质中重金属以Cu和Ni为主,白银市以Cd、Cu和Pb为主,重金属元素的生物可利用态和潜在可利用态质量分数高,平均约占各金属,总量的60%～90%,对周围环境具有很大的潜在生态危害性.     

富硒土壤镉的赋存状态

采用7步提取法对某地富硒土壤样品进行镉的形态分析,发现镉质量分数较高,镉平均为0.374 mg/kg,最高为0.943 mg/kg。各形态含量差异较大,基本是残渣态离子交换态铁锰氧化物结合态腐殖酸结合态强有机结合态碳酸盐态水溶态,在7种形态中以残渣态、离子交换态、铁锰氧化物结合态3种形态占主导。     

改进BCR法-电感耦合等离子体发射光谱法测定矿产品堆场土壤中镉砷铅的化学形态

矿产品堆场土壤中重金属在环境中富集,随着元素的迁移、转化及地下水的循环,成为环境污染问题。本文将改进的顺序提取法(BCR)应用于矿产品堆场土壤中Cd、As、Pb的化学形态分析,结合这三种元素的性质,将堆场土壤中Cd、As、Pb分为可交换态、可还原态、可氧化态和残渣态,并利用电感耦合等离子体发射光谱法测定其含量。采用形态分析标准参考物质GBW 07436验证了三步提取态的准确性,并对6个矿产品堆场土壤中Cd、As、Pb形态含量进行分析,三步提取态加上残渣态质量分数之和与重金属总量进行了比较,回收率为85.54%~102.88%。通过对矿产品堆场土壤实际样品分析,Cd、As、Pb三种元素非残渣态含量顺序为Cd(79.40%~94.94%)Pb(24.27%~37.73%)As(22.89%~31.51%),表明Cd元素较为容易进入生物圈。该方法解决了港口堆场土壤中重金属化学形态提取问题,对污染土壤的治理具有指导意义。     

Speciation analysis of metals （Tl, Cd and Pb） in Tl-containing pyrite and its cinder from Yunfu Mine, China, by ICP-MS with sequential extraction

The speciation of heavy metals such as thallium, cadmium and lead existing in pyrite and pyrite cinder was analyzed by ICP-MS with a sequential extraction procedure. The distribution patterns of these metals including exchangeable, reducible, oxidizable and residual fractions were obtained. Tl, Cd and Pb in pyrite and pyrite cinder samples from each extraction step were determined by inductively coupled plasma mass spectrometry (ICP-MS). Under the optimized instrumental conditions, detection limits of Tl, Cd and Pb in different matrices were within the range of 0.006–0.07 μg/L, and the relative standard deviations ranged from 0.8% to 1.2%. The accuracy of Tl, Cd and Pb determination was checked by analyzing two certified reference materials. The results demonstrate that trace Tl, Cd and Pb in the samples can be accurately determined. The sequential extraction results revealed that the percent contents of Tl, Cd and Pb in exchangeable, reducible and oxidizable fractions in pyrite cinder are different from those in pyrite and in pyrite cinder. Tl, Cd and Pb mostly are distributed in residual fraction. Therefore, the mobility of metals in pyrite is higher than that in pyrite cinder. Although distributions of Tl, Cd and Pb in the non-residual fraction are not dominant in pyrite cinder, the total concentrations of them could not be ignored. Consequently, attention must be paid to the risk of potential pollution by pyrite cinder.     

Potential contaminants at a dredged spoil placement site,Charles City County,Virginia, as revealed by sequential extraction

Backfills of dredged sediments onto a former sand and gravel mine site in Charles City County, VA may have the potential to contaminate local groundwater. To evaluate the mobility of trace elements and to identify the potential contaminants from the dredged sediments, a sequential extraction scheme was used to partition trace elements associated with the sediments from the local aquifer and the dredged sediments into five fractions: exchangeable, acidic, reducible, oxidizable, and residual phases. Sequential extractions indicate that, for most of the trace elements examined, the residual phases account for the largest proportion of the total concentrations, and their total extractable fractions are mainly from reducible and oxidizable phases. Only Cd, Pb, and Zn have an appreciable extractable proportion from the acidic phase in the filled dredged sediments. Our groundwater monitoring data suggest that the dredged sediments are mainly subject to a decrease in pH and a series of oxidation reactions, when exposed to the atmosphere. Because the trace elements released by carbonate dissolution and the oxidation (e.g., organic matter degradation, iron sulfide and, ammonia oxidation) are subsequently immobilized by sorption to iron, manganese, and aluminum oxides, no potential contaminants to local groundwater are expected by addition of the dredged sediments to this site.     

Speciation of heavy metals in electroplating industry sludge and wastewater residue using inductively coupled plasma

The speciation of metals in environmental samples is a critical factor in assessing the potential environmental impacts, before their disposal. The distribution and speciation of toxic heavy metals in plating wastewater residues and sludge was investigated for four samples using sequential extraction method. Tessier method was used to fractionate the metal content into exchangeable, acid extractable, reducible and oxidizable fractions. Residual and total metal contents were determined in aqua regia digest. The extracts were analysed for metals using inductively coupled plasma -atomic emission spectrometry. The bioavailable fraction (exchangeable and acid extractable fractions) is comprised less than the other forms. The oxidisable and reducible forms are dominants for all the four samples studied. The major metal constitute in the samples is iron, the wastewater residue contains (12.3 and 7.4 g/Kg respectively on dry basis) and the sludge contains (31.5 and 41.6 g /Kg) respectively. Cr concentration is higher in wastewater residue of second electroplating industry. The descending order of the average total metal contents for these four samples were Fe > Cr > Sn > Zn >Cu > Ni > Mn > Pb > Cd > Ag. Based on the average of absolute values for the four samples the highest bioavailability order of metals is Cr (39 %) in wastewater residues and Zn (32 %) in sludge samples. Metal recovery was good, with < 10 % difference between the total metal recovered through the extractant steps and the total metal determined using aqua regia extract.     

Fractionation of U,Th, Ra and Pb from boreal forest soils by sequential extractions

To determine the mobility of natural radionuclides in boreal forest soil, a five-step sequential extraction procedure was carried out on soil samples taken from various depths down to 3 m on Olkiluoto Island, Finland, where there are plans to construct a spent nuclear fuel disposal repository in the bedrock. The extracted fractions studied were exchangeable, acid-soluble, reducible, oxidizable and tightly bound. It was found that the extractability of most of the radionuclides studied was dependent on the sample grain size and depth. All the elements were concentrated in the smallest grain size samples (<0.063 mm). The extraction behaviour of Th, however, did not vary with sample depth, and only about 10% of the Th was extracted by the time of the final extraction step. Stable Pb and ²¹⁰Pb, as well as Ba and Ra concentrations were strongly correlated in the extractions. Radium and Ba were leached more readily than the other elements; approximately 17% of the total Ra was found in the first fraction extracted, representing exchangeable ions. Uranium was more mobile in the topsoil horizons than in the lower horizons. In the topsoil samples, an average of 51% of the extractable U was leached in the second extraction step, representing the elements soluble in weak acids, whereas only 13% of the U in the subsoil samples was extracted in this step. This is probably due to changes in soil redox conditions lower down the soil profile. The extraction behaviour of Pb and Fe also suggests the presence of more reducing conditions in the deeper soil horizons, because the percentage of extractable Pb and Fe in the oxidizable fraction increased with sample depth.     

铜陵矿区水系沉积物中重金属存在形态特征研究

通过对铜陵水系沉积物重金属形态分析实验,研究了重金属各种形态在沉积物中分布特征。分析结果显示,矿区水系沉积物中Cu、Pb、Zn、Cd等重金属含量都显著的高于对照样品,水系已经受到重金属的污染。提出了防治和改善铜陵地表水环境污染的措施。     

热水解-离子选择电极法测定海相碳酸盐岩中的氟

采用热水解法对样品进行预处理,离子选择电极法简易快速测定海相碳酸盐岩中氟元素的含量。方法检出限为25.1μg/g,精密度(RSD,n=11)为5.28%,回收率为96.5%~107.8%,结果令人满意。     

Characteristics of distribution and chemical speciation of heavy metals in environmental mediums around Jinchang mining city,Northwest China

Heavy metal contamination was the main environmental problem around the Jinchang Ni–Cu mine area of Gansu, Northwest China. The concentration of heavy metals (Cr, Cu, Ni, Pb, and Zn) in various environmental mediums around the Jinchang Ni–Cu mine area were analyzed using atomic absorption spectrometry (AAS). The different chemical speciation of heavy metals was extracted using BCR (European Community Bureau of Reference) sequential extraction procedure, and the concentration of chemical speciation of each heavy metal was measured by inductively coupled plasma-atomic emission spectrometry. The results showed that Cu and Ni were the most important heavy metal pollutants in various mediums including cultivated soils, dust on slagheap surfaces, tailings, and sediments in waste water drains. In the tailings and sediments, the concentrations of Ni were obviously higher than those of Cu, whereas, in the soil and dust, the concentrations of Cu were higher than those of Ni. Analysis of chemical speciation indicated that Cr and Zn were mainly in residual fraction; Cu was mainly in oxidizable fraction; Ni was mainly in reducible fraction and acid soluble fraction; and Pb was mainly in reducible fraction and residual fraction. The extent of contamination of various environmental mediums was different because the heavy metals were derived from different sources. Furthermore, the mobility of various heavy metals was different because of the different distribution of chemical speciation.     

Metal mobility due to storm events on an impacted hillslope in Palmerton,PA

Water samples were collected continuously from perennial springs on a hillslope impacted by historical metal deposition to study the hydrologic and geochemical behavior of a watershed during storm events, and assess the natural attenuation of metals in soil. Water samples were collected throughout storm hydrographs for inorganic chemistry analyses, and a sequential extraction was performed on watershed soil samples. Despite 30 a of natural attenuation at the site, Zn is mobilized into streamwater during storm events, with concentrations ranging from 18 to 452 μg/L. While Cd and Pb concentrations in water samples remained relatively constant, Zn concentration increased corresponding with the peak in the hydrograph indicating this metal is being released from adsorption sites located in an unsaturated zone that is temporarily inundated during storm events. Zinc is held on exchangeable, water and acid soluble sites, and in the reducible fraction, further indicating Zn may be released as a result of the downward movement of water through the soil profile. Equilibrium geochemical modeling predicts Zn desorption with a decrease in pH, which may occur as a result of site re-vegetation. The long legacy of metal emissions from a historical smelting operation will continue to limit the attenuating ability of this site.     

Determination of heavy metals in sediments of the Ergene River by BCR sequential extraction method

Utilizing the sequential extraction procedure (acid soluble, reducible, oxidizable, and residual) proposed by The European Community Bureau of Reference (BCR), the trace metals present in the sediments of the Ergene River, Turkey, were determined. The sediment samples were collected from 10 sampling sites and analyzed to identify the concentrations of cadmium, cobalt, chromium, copper, manganese, nickel, lead and zinc. The flame atomic absorption spectrometer was used for metal determination. The validation of the results was checked by the analysis of the BCR-701 standard reference material. The relationship existing between the sediment characteristics and metal fractions was identified using the correlation analysis. Hierarchical cluster analysis was performed to find out the grouping of the sampling sites based on the similarities of the heavy metals in the bioavailable fraction. When the extractable amounts of heavy metals are considered, the quantity of the mobile fractions (viz., acid soluble, reducible, and oxidizable) of the heavy metals is observed to be higher when compared with that of the immobile fraction (residual). This might be caused by the anthropogenic sources. Besides, it was statistically discovered that the organic matter, pH and clay contents could influence the bonding of the analyte metals in various forms. The cluster analysis revealed three clusters of the sampling stations, with group I (S5-8) and group II (S3, S4 and S9) showing higher environmental risks. The risk assessment code indicated that the highly mobile soluble fractions of Mn, Zn, Cd and Co created a high environmental risk which could result in negative impacts on the aquatic biota.