青藏高原东部表土磁化率特征与环境意义

现代表土磁化率与气候因子关系的研究是黄土古气候重建的重要内容,在黄土高原地区取得了重要进展,但在青藏高原地区相对不足。在青藏高原东部系统采集了106个表土样品,分析了其磁化率的变化特征;并通过表土磁化率与气候因子的相关分析,讨论了气候因子对高原东部现代表土低频磁化率和频率磁化率的影响。结果表明：研究区表土磁化率特征主要受到温度和降水量的影响,水热组合差异影响表土磁化率值的高低。低频磁化率与气候因子的相关性较弱,总体上与温度的相关性优于降水量,可能表明其与气候因子的关系比较复杂;频率磁化率百分比与降水呈较好的正相关关系,表明该指标对降水量的变化更为敏感,可以用于青藏高原东部的古降水定量重建。     

武汉市东湖周边近地表土壤磁化率特征及其环境意义

测量了武汉市东湖周边3个采样区60个土壤样品的磁化率及24个代表样品的重金属元素质量分数,对土壤磁化率和重金属元素质量分数进行了相关分析与聚类分析,探讨应用土壤磁化率参量及测量技术对大范围区域污染环境评价的指示意义.结果表明,土壤磁化率与重金属元素Ca、Cu、Pb、Sr、Zn质量分数显著相关,相关系数分别高达0.930,0.836,0.864,0.879和 0.879;重金属元素Ba、Cr、Fe、Mg、Mn质量分数与磁化率中度-弱相关,相关系数分别为0.447,0.303,0.557,0.528,0.333.聚类分析结果表明,不同采样区地表土壤的污染源之间存在一定差异.这些结果为应用土壤磁化率(尤其是原位磁化率)测量技术在该区进行大尺度和高精度环境评价提供了基础.     

Field and dual magnetic susceptibility proxies for heavy metal pollution assessment in the urban soil of Al-Karak City, South Jordan

A total of 115 urban soil samples collected on grid bases from Al-Karak, South Jordan, were investigated for their field and dual-frequency magnetic susceptibility (χ _field, χ _d) and heavy metal content using Bartington susceptibility meters and ICP-MS. The upper soils have higher magnetic susceptibility values than lower soils, and large particles contain more heavy metals and higher magnetic susceptibility than smaller particles. This might be attributed to the lack of pedogenesis due to arid climate influence. Within the upper soil all heavy metal showed positive significant correlation with upper soil low-frequency χ _dlf. This was evident from the distribution maps produced by Surfer 9.0 for χ _dlf and heavy metals. The results showed that higher χ _dlf is associated with traffic-dominated sites more than other areas. The frequency-dependent susceptibility (χfd %) falls between 2 and 10 %, which indicate the presence of admixture of fine supermagnetic particles. Mildly correlation exists between χfd % and χ _dlf, which implies that soils contain anthropogenic multi-domain grains. Selected samples have been analyzed for their mineral constituents; the results indicate the presence of magnetite as the main magnetic mineral. This confirms the anthropogenic source of pollution mainly from the vehicle-related materials. The results indicate the applicability of magnetic susceptibility for pollution detection.     

贵阳城市土壤重金属元素形态分析

选取贵阳市62个代表性的表层土壤样品,分析了其重金属元素的含量和存在形态.结果表明,贵阳城市土壤中5种重金属元素(Cr、Cu、Pb、Zn和Cd)的含量较高,且变化较大.表层土壤中Cr、Cu、Zn主要以残渣态形式存在,Pb主要以可氧化态形式存在.Cd可还原态含量高达47.5%,残渣态含量最低,说明Cd较活泼,具有潜在的环境影响能力.     

Correlation between magnetic susceptibility and distribution of heavy metals in contaminated sea-floor sediments of Hong Kong Harbour

 Magnetic susceptibility measurements were conducted on 24 vibrocores obtained from an area located off the northeastern coast of Lantau Island in Hong Kong. High intensities of magnetic susceptibility were detected in the uppermost sections of the majority of the cores. Several magnetic parameters measured for one of the cores suggest that the variations in the magnetic characteristics over depth are mainly due to varying concentrations of the magnetic minerals. Since a strong correlation has been found between magnetic susceptibility and the heavy metals Pb, Cu, Zn and Cr, an anthropogenic contamination origin is thought to be the cause. The present study shows that magnetic susceptibility is a fast, inexpensive and non-destructive method for the detection and mapping of contaminated sediments. Received: 12 August 1997 · Accepted: 18 November 1997     

Environmental magnetic and geochemical characteristics of Chennai coastal sediments,Bay of Bengal,India

In this study, environmental magnetic, heavy metal and statistical analyses were conducted on 21 surface sediments collected from Chennai coast, India, to examine the feasibility of heavy metal pollution using magnetic susceptibility. The Chennai coastal sediment samples are dominated by ferrimagnetic minerals corresponding to magnetite-like minerals. The percentage of frequency dependent magnetic susceptibility reflects the presence of super-paramagnetic/single domain magnetic minerals in Chennai harbour, Cooum and Adayar rivers sediments. High pollution load index in sample E1, E2, CH7, C11, C12 and A16 is mainly due to anthropogenic activities such as, harbour activities, Cooum and Adayar rivers input and industrial effluent. Factor analysis shows that the magnetic concentration dependent parameters (χ, χ _ARM and SIRM) covary with the heavy metal concentrations, suggesting that the input of magnetic minerals and heavy metals in Chennai coastal sediments are derived from the same anthropogenic sources. Strong correlation obtained between pollution load index (PLI) and concentration dependent parameters (χ, χ _ARM and SIRM) for the polluted samples with magnetic susceptibility excess of 50×10^− 8 m³kg^− 1. Significant correlations between heavy metals and magnetic susceptibility point out the potential of magnetic screening/monitoring for simple and rapid proxy indicator of heavy metal pollution in marine sediments.     

磁化率对土壤重金属污染的指示性研究——以沈阳新城子区为例

通过对399件表层土壤磁化率参数与化学组成的分析测试,较系统地总结了沈阳新城子区土壤磁化率特征,并初步进行了磁化率对土壤重金属污染的指示研究。结果表明:(1)不同土壤类型中磁化率差异较大,棕壤中由于人为作用较大,其均值最高。不同堆积类型中磁化率差别较大,洪积物和残坡积物中平均值最高,冲积物中最低。不同农作物对元素的需求不一样导致磁化率的含量变化范围存在着区别。(2)土壤的磁化率与土壤中Cd、Pb、Hg、Cu、Zn等重金属元素含量呈显著正相关,且与土壤pH值呈显著负相关关系,能反映出土壤酸化的状况,对土壤污染程度有较好的指示性。(3)利用磁化率可以快捷地划分污染区。     

Spatial distribution and contamination assessment of heavy metals in urban topsoil from inside the Xi’an second ringroad, NW China

The paper reports the spatial distribution and contamination level of heavy metals (Co, Cr, Cu, Mn, Ni, Pb, Zn and V) in urban topsoil from the interior area of the second ringroad of Xi’an city, China, based on X-ray fluorescence spectroscopy measurements. Geostatistical analysis shows that Co, Cu, and Pb have similar spatial distribution patterns. Heavy traffic density mainly contributed to the high concentrations of Co, Cu and Pb. The spatial distribution of Cr coincides with the industrial activity, whereas the spatial distribution of Zn differs from other heavy metals. The high concentrations of Zn coincide with heavy traffic and high population density. For Mn, Ni and V, natural factors are important in controlling their distribution. The calculated geoaccumulation indices indicate that urban topsoil inside the Xi’an second ringroad was uncontaminated by Cr, V, Mn and Ni, while Pb, Cu, Co and Zn are classified as uncontaminated to moderately contaminated with means of 0.64, 0.46, 0.26 and 0.21, respectively. The Nemero synthesis pollution index of these heavy metals revealed that the topsoil inside Xi’an second ringroad has been heavily contaminated due to anthropogenic activity.     

Soil metal pollution from former Zn–Pb mining assessed by geochemical and magnetic investigations: case study of the Bou Caid area (Tissemsilt,Algeria)

Former zinc and lead mines that have been operating for half a century are located in the massif of Bou Caid (Tissemsilt, Algeria). Hazardous heavy metals emitted from the mines are abundant in the surrounding soil and cause strong metal pollution in the region. This paper investigates the extent of lead and zinc mine activity derived pollution by characterizing both magnetic and geochemical properties of samples collected in the vicinity of the mines. The results of the magnetic study show the coexistence of magnetic minerals such as magnetite, hematite and goethite. Analyses on surface soils and weathered rocks suggest that hematite and goethite have ore-related lithogenic origins. Magnetic susceptibility shows a positive correlation with lead content when present in low-to-medium concentrations (< ~500 mg/kg). At higher lead concentrations, there is no correlation with magnetic susceptibility. The relationship between magnetic susceptibility and zinc content is not straightforward. These observations are explained by the higher affinity of Pb to iron oxides at lower pollution levels and their preferential bonding to carbonates when Pb and Zn contents are extremely high, as demonstrated by Iavazzo et al. (J Geochem Explor 113:56–67, 2012) in a study of former Zn–Pb mine in Morocco. Based on the general features of the spatial maps of field-measured magnetic susceptibility, mass-specific magnetic susceptibility, Pb and Zn contents, it is concluded that field magnetic measurements provide a good qualitative proxy of pollution spread out of the mining galleries, while laboratory measurements afford a more detailed investigation of the links between iron oxides and the main heavy metals in the ore.     

中国东部表层土壤磁化率特征及其指示意义

磁化率是环境磁学研究中较常用、较易获得的指标之一,但其解释和意义又最为复杂.对采自中国东部从北到南涵盖中国主要气候带的风化-成壤成因的79个表层土壤样品进行高、低频磁化率和非磁滞剩磁测试并分析其与降水量、年均温等气候参数的关系.结果表明:(1)发育于不同类型母岩的风化-成壤成因表层土壤磁学性质之间存在显著差异,各磁化率参数与气候条件参数之间的关系大不一样,在大空间尺度进行磁学与气候条件的关系研究时,必须充分考虑地质背景与母岩类型的差异.(2)发育于花岗岩的表层土壤非磁滞剩磁磁化率与年降水量和年均温间呈显著负相关关系;而发育于玄武岩的表层土壤非磁滞剩磁磁化率与年降水量呈显著正相关关系.被广泛认可的黄土-古土壤序列磁化率与成壤的关系不一定适用于大空间尺度的其他气候区域.(3)在风化-成壤过程中,磁性颗粒有变细的趋势,但降水强度增大时,一些超细颗粒较易被搬运离开原地,单一磁学参数结果难以反映气候条件及环境变化.(4)风化-成壤成因表层土壤非磁滞剩磁磁化率能较好地反映风化成因土壤的风化程度,但风化-成壤表层土壤磁学性质变化的机制特别是对相应土壤剖面的磁性矿物迁移转化有待深入研究.      

Magnetic properties and heavy metal content of sanitary leachate sludge in two landfill sites near Bandung,Indonesia

Magnetic properties and heavy metal content of landfill leachate sludge samples from two municipal solid waste disposal sites near Bandung, West Java, Indonesia, and their correlation with heavy metals are studied in the present work. Leachate was found to be sufficiently magnetic with mass-specific magnetic susceptibility that varies from 64.8 to 349.0 × 10⁻⁸ m³ kg⁻¹. It is, however, less magnetic than the soils around the landfill sites. The magnetic minerals are predominantly pseudo-single domain and multidomain magnetite. Leachate samples from the older but inactive disposal site, Jelekong, are found to be more magnetic than that from Sarimukti, the younger and active site. The enhancement of leachate due to the soil-derived ferrimagnetic particles is possibly the same for both Sarimukti and Jelekong. The fact that strong correlation between magnetic parameters and heavy metals is observed in Jelekong but is absent in Sarimukti suggests that the use of magnetic measurement as a proxy measurement for heavy metal content in leachate is plausible provided that the magnetic susceptibility exceeds certain threshold value. Moreover, the accumulation of magnetic minerals and heavy metals in leachate might depend on the activity and the age of landfill site.     

Assessment of heavy metals contamination in urban topsoil from Changchun City,China

Due to the rapid urbanization and industrialization that has occurred in China over the last few decades, metals have been continuously emitted into the urban environment and now pose a serious threat to human health. Indeed, there is a growing concern over the potential for pollution of urban soils with heavy metals. Therefore, an extensive soil survey was conducted in urban areas of Changchun, China, to evaluate the current status of heavy metal contamination in soils and to evaluate its potential sources. A total of 352 samples of urban soils were collected from urban areas of Changchun using a systematic sampling strategy in which one sample per km² was taken (0 ~ 20 cm). The levels of Cu, Pb, Zn and the major elements (Mn, Al₂O₃, CaO, Fe₂O₃, MgO, SiO₂, K₂O and NaO) were then determined by X-Ray fluorescence spectrometry (XRF), while the level of Cd was determined by graphite furnace atomic absorption spectrometry (GF-AAS), and the Hg and As concentrations were determined by atomic fluorescence spectroscopy (AFS). The results indicated that, when compared with the background values of topsoil in the Changchun region, the topsoil in urban areas were enriched with metals, particularly Cu, Cd, Zn, Pb and Hg. The results of correlation coefficient analysis showed that Hg, As, Cd, Cu, Pb and Zn were significantly positive correlated with each other, while Cr and Mn formed another group. Moreover, significantly positive correlations were observed between pH and Zn, Pb, Cu, Cd, As and Hg, indicating that pH influences the distributions of these metals in urban soils in Changchun. Principal component analysis (PCA) was conducted to identify sources of heavy metals and the results revealed distinctly different associations among the trace metals and the major elements in the urban soils. The concentration of Cr appeared to be controlled by the parent material (natural sources), while Cu, Pb and Zn were mainly from vehicle emissions, with Zn primarily coming from vehicle tires. Additionally, Hg and As primarily originated from coal combustion, while Cd was mainly associated with industrial sources. According to the pollution index (PI) of each metal, the overall levels of metal pollution were not especially high, but there were clearly contaminated sites concentrated in the central and northeast portion of the studied region. The Nemerow integrated pollution index (NIPI) of the seven metals also indicated that urban soils in Changchun city were classified as having low level of pollution.     

泉州城市表层土壤中金属元素来源分析

采集了泉州市47个城市表层土壤样,用ICP-MS检测技术,研究了土壤中26种重金属元素的富集特征、环境风险及污染来源。富集因子结果显示,与泉州市土壤背景值相比,Li、Ni、Co、Cu、Zn、Sr、Cd、Sn、Sb、Pb、Ta在城市表层土壤中的富集因子大于1,而Ti、V、Cr、Fe、Mn、Ga、Ge、As、Rb、Y、Nb、Cs、Bi、Th、U的富集因子小于1。从功能区上看,工业区污染最为严重,其次依次为农业区、商住区、城市绿地、交通区。环境风险指数表明,泉州市城市表层土壤中重金属污染具有极高的环境风险,达到极高风险级别的样品占48.9%。采用多元统计分析方法对土壤样品中各金属元素来源进行解析,结果表明,研究区城市表层土壤中金属元素总体可分成5类：①交通运输类（Sn、Pb、Sb、Bi）;②工业因子类（Cr、Co、Ni、Fe、Mn）;③自然因子类别（Ga、Ge、Ti、V、Cu）;④混合因子类别（Zn、Cd、Sr、Th、U、Y、As、Cs、Nb、Ta、Rb）;⑤生活垃圾因子类别（Li）。     

泥河湾盆地沉积物粒度组分与磁化率变化相关性研究

以泥河湾盆地郝家台剖面为例,分析沉积物粒级组分与磁化率大小变化的相关性。从厚约 12 2m的剖面选取 80 0多个样品,分别测试从 0.2～ 5 0 0 μm各个粒度区间颗粒的百分含量和质量磁化率。通过计算它们之间的相关关系,认为湖相沉积物磁化率的变化与 0.2～ 35 μm间细粒物质的含量,特别是与 0.2～ 7.5 μm区间悬浮物质的含量反相关,而与 35～ 5 0 0 μm间较粗粒物质的含量正相关。这种相关性与顶部的黄土堆积刚好相反,反映了二者之间磁化率不同的变化机制。据此可认为以外源碎屑输入为主的湖泊中,沉积物磁化率的变化主要受控于外源铁磁性矿物,它反映了湖水面的升降,蕴涵着一定的古气候信息。     

Heavy metals in Xuzhou urban roadside topsoils (China): magnetic characterization and enrichment mechanism

Heavy metal contamination is prevalent in urban areas where soil represents a significant sink. Urban topsoil samples were collected and metal concentrations including Pb, Zn, Cu, Cd, Ni and Co were measured by inductively coupled plasma mass spectrometry. All analyzed metals showed elevated concentrations compared to local background concentrations with the exception of Co. Cadmium was the metal most enriched in the analyzed area, presenting enrichment factor, on average, of 16.5. Mineral magnetic concentration parameters (χlf and SIRM) exhibited significant relationships with Pb, Zn, Cu and Cd, respectively. Zinc, Co and Ni exhibited a substantial build-up in the finest particles (<28 μm). Enrichment was positively correlated with carbonate complexation constants (but not bulk solubility products) and suggests that the dominant mechanism controlling metal enrichment in these samples is a precipitation of carbonate surfaces that subsequently adsorb metals.     

Geochemical and mineral magnetic characterisation of urban sediment particulates,Manchester, UK

Urban sediments are part of a complex system in which particulates accumulate potentially toxic pollutants, ultimately posing a threat to urban water-bodies and public health. It is therefore important to recognise sources, signatures and pathways of urban particulates. Urban sediment samples were analysed from both inner and outer city road surfaces of Manchester, UK. High metal concentrations, coupled with the largely ferrimagnetic multi-domain (MD) mineral magnetic composition of the particulates, indicate inputs of anthropogenic origin, primarily particulates derived from automobiles, as being the dominant source to the urban sediment system. Iron and Pb concentrations show a clear spatial trend, whereby concentrations are enhanced in the inner city samples. Lead concentrations for inner and outer city samples average 354 and 185 μg g⁻¹, respectively. Iron concentrations for inner and outer city samples average 11302 and 6486 μg g⁻¹, respectively. Sequential extraction analysis shows the metals Mn, Fe, Zn and Pb are largely associated with the reducible fraction, whereas Cu is largely associated with the oxidisable fraction. Zinc is the only metal showing significant association with the exchangeable fraction (up to 33%), suggesting that it may be the most susceptible metal to mobilisation during runoff. Metal fractions identified as showing larger associations with the reducible and oxidisable fractions will continue to be vulnerable to mobilisation as a result of changes in ambient pH and/or redox conditions. Mineral magnetic concentration parameters, such as the saturation isothermal remanent magnetisation (SIRM), together with hysteresis parameters such as the coercive force and interparametric ratios (such as (B_o)_cr/H_c and IRM_-100mT/SIRM) show that ferrimagnetic MD minerals dominate the Manchester urban sediments. Average results for frequency-dependent susceptibility as a percentage (2%) suggest that the composition of these Manchester sediments is not dominated by soil-derived material, and therefore magnetically coarser, anthropogenically-derived material is dominant. Unlike Pb and Fe concentrations, mineral magnetic characteristics of the Manchester urban sediment samples exhibit no significant spatial variation.     

Geostatistical analyses and fractionation of heavy metals in urban soil from industrial district in Weinan, NW China

The concentrations of metals (Pb, Cr, Ba, Zn, V, Mn, Co, Cu, Ni and As) in 38 soil samples collected from the industrial district in Weinan (NW China) were determined by wavelength dispersive X-ray fluorescence spectrometry. The magnetic parameters of soil including low-/high-frequency susceptibility and frequency-dependent susceptibility were measured. The modified three-step BCR sequential extraction procedure was used to evaluate mobility, availability and persistence of trace elements in urban soil samples. Multivariate (principal component analysis, clustering analysis and correlation analysis) and geostatistical analysis (ArcGIS tools) were applied to the obtained data to evaluate the analytical results and to identify the possible pollution sources of metals as well as geo-spatial distributions. The results revealed that the sampling area was mainly influenced by two main sources: (1) Ba, Cu, Pb, Cr and Zn were mainly derived from industrial sources, which combined with coal combustion as well as traffic factor. The mobility sequence based on the sum of the BCR sequential extraction stages was: Pb (53.79 %) > Zn (51.78 %) > Cu (50.96 %) > Ba (42.59 %) > Cr (18.47 %). Pb was the metal predominantly associated (~46.86 %) with the form bound to Fe/Mn oxides, and the highest percentage of Zn was exchangeable and carbonate-bound fraction. Cu was present mainly in organic fraction, while the residual fraction was the most dominant solid phase pool of Cr (~81.53 %) and Ba (~57.41 %). (2) Mn, V, Co, As and Ni in the study area were consistently from natural sources. The analysis of enrichment factors indicated that urban soils in Weinan City were classified as having significant enrichment by Ba, Cu, Pb, Cr and Zn. The overall results proposed the future tactics for Weinan environment quality control on a local scale that concerned not only the levels of risky, but also the industrial emission abatement techniques as well as urban setting.     

北京市昌平区钻孔岩芯的磁化率与粒度组份变化的相关性研究

以昌平区钻孔岩芯为例,分析沉积物粒级组分与磁化率大小变化的相关性。从厚约150 m的剖面选取590多个样品,分别测试从0.5~500 μm各个粒度区间颗粒的百分含量和磁化率。通过计算它们之间的相关关系,认为湖相沉积物磁化率的变化与0.5~30 μm间细粒物质的含量,特别是与0.5~10 μm区间悬浮物质的含量反相关,而与65~500 μm间较粗粒物质的含量正相关。这种相关性与黄土沉积刚好相反,反映了二者之间磁化率不同的变化机制, 蕴涵着一定的古气候信息。     

Use of multivariate statistical analysis to determine the relationship between the magnetic properties of urban topsoil and its metal, S, and Br content

Multivariate statistical analysis has been used for detailed examination of the relationship between the magnetic properties of Xuzhou urban topsoil, for example concentration-dependent properties (mass magnetic susceptibility (χ), susceptibility of anhysteretic remanent magnetization (χ _ARM), saturation isothermal remanent magnetization (SIRM), soft remanent magnetization (SOFT), and frequency-dependent magnetic susceptibility (χ _FD)) and feature-dependent properties (S _{−100 mT} ratio, SIRM/χ ratio and F _{300 mT} ratio), and the concentrations of metals (Ti, Fe, Cr, Al, Ga, Pb, Sc, Ba, Li, Cd, Be, Co, Cu, Mn, Ni, V, Zn, Mo, Pt, Pd, Au, As, Sb, Se, Hg, Bi, Ag, and Sn), S, and Br in the soil. The results show that SIRM/χ ratios correlate best with the heavy metals (Hg, Cr, Sb, As, and Bi) which are mainly derived from coal-combustion emissions whereas χ _FD correlates best with the metals (Al, Ti, V, Be, Co, Ga, Mn, and Li) which principally originate from soil parents. Concentration-dependent magnetic properties (χ _ARM, χ, SIRM, and SOFT) correlate well with elements (Se, Pb, Cu, Zn, Fe, Ag, Sc, Ba, Mo, Br, S, Cd, Ni, etc.) which are mainly derived from road-traffic emissions. For the same chemical element, χ _ARM, SIRM, and SOFT values are frequently better correlated than χ values, and χ _ARM values are the best indicators of the concentrations of these elements associated with traffic emissions in this study area. In addition, S _{−100 mT} ratios significantly correlate positively with Se, Sc, Pb, Cu, Zn, Mo, and S whereas F _{300 mT} ratios only correlate positively with Pt and negatively with Fe. These results confirm the suitability of different magnetic properties for characterizing the concentrations of heavy metals, S, and Br in Xuzhou urban topsoil.     

Heavy metal pollution and soil magnetic susceptibility in urban soil of Beni Mellal City (Morocco)

The assessment of anthropogenic impact in the urban environment can be evaluated according to heavy metal contents of soils such as Pb, Cu, Zn, Cd and Fe. These elements have more affinity to establish metallic bond with ferrous material leading to enhancement of soil magnetic susceptibility. The objective of this study was to undertake joint magnetic and geochemical investigations of road-side urban soil materials to address the environmental pollution of Beni Mellal city that has been subjected to environmental stress, due to population overpressure and related urbanization. Twenty three soils magnetic susceptibility profiles were made along 5 km peripheral national road (N8) in Beni Mellal. The magnetic survey reported here for the first time on this City’s topsoils tries to establish the link between magnetic properties and the content of heavy metals. High magnetic susceptibility values and high contents of heavy metals were found near the paved edge of the road and within the place reserved as large engine park. Magnetic extracts of highly polluted areas and unpolluted soil (olive plantation) were analyzed by SEM coupled with RDX in order to discriminate anthropogenic magnetic spherules and pedo-lithogenic magnetite-like minerals. Magnetic mineralogy determined by Mössbauer spectroscopy suggests the presence of hematite, magnetite and goethite in highly polluted areas. The iron oxides and especially goethite are efficient in incorporating and/or adsorbing foreign ions.