Geochemical features of heavy metals in core sediments of northwestern Taihu Lake, China

Sequential core sediments from northwestern Taihu Lake in China were analyzed for grain size, organic carbon and heavy metal content. The sediments are composed of organic-poor clayey-fine silts. The chemical speciations of Cu, Fe, Mn, Ni, Pb, and Zn were also analyzed using the BCR sequential extraction procedure. Cu, Fe, Ni, and Zn are mainly associated with the residue fraction; Mn is concentrated mainly in exchangeable/carbonate fraction and residue fraction; and Pb mainly in Fe/Mn oxide fraction and organic/sulfide fraction. The exchangeable/carbonate fractions of Cu, Fe, Ni, Zn and Pb are lower. The fractions of Ni, Pb and Zn bound to the Fe/Mn oxide have significant correlations with reducible Mn; the organic/sulfide fractions of Cu, Mn, Ni, Pb, and Zn have significant correlations with TOC. The extractable fractions of Cu, Mn, Ni, Pb, and Zn are high at the top 4 cm of the core sediments as compared to those in the deeper layers, showing the anthropogenic input of heavy metals is due to rapid industrial development. The heavy metal pollution history of the sediments has been recorded since the late 1970s, determined by the result of ^137Cs dating.     

Contamination and bioavailability of heavy metals in sediments from the Yangtze River Delta Region

The Yangtze River Delta Region is one of the most important economic development areas in China. In the process of its industrialization and urbanization, a great deal of wastewater is poured into rivers, lakes and coasts. Researches on contamination and bioavailability of heavy metals can help us to assess the ecological risks in the aquatic environment of the Yangtze River Delta. The samples were collected from three environmental compartments including the Yangtze River, Taihu Lake, and the south coast of Jiangsu. The concentrations of heavy metals were determined by ICP-MS. Metal speciation was determined by the sequential extraction procedure modified based on Tessier＇s scheme. Among the seven elements of Cu, Pb, Zn, Cr, Cd, Co, Ni detected, the contents of Cr, Zn did not vary significantly, while Cd and Pb varied significantly. Compared to the background values （loess in the basement）, all metals detected except Co, Cr exceeded the background level. Cd had the greatest exceeding values, reaching 2 to 7 times. Ni and Pb were followed. The contents of Zn were comparatively high in lake sediments, especially in the lake bays. Ni was enriched in fiver sediments and Cu was highest in sediments from the Yangtze River estuary. Cd and Pb were concentrated in the coastal sediments. Comparatively, in space, Cr was associated with the carbonate fractions in the bay of lake. Cu-bound Fe-Mn oxides and Ni in residual form were highest in the open lake. In the river environment, Fe/Mn oxide-bound Pb, exchangeable Cd were the highest fractions. In the estuary environment, Pb and Zn bound carbonates, Cd-bound Fe-Mn oxides are the largest fractions. Cd in the exchangeable fraction, Cu-bound Fe-Mn oxides had the larger proportions in the coast. In general, the bioavailability of Cu and Cd were high in lake environment, the available Pb, Cd were remarked in river environment, and Pb and Zn were easily assimilated by creatures in estuary.     

Comparison of components and distribution of heavy metals in sediments, suspended particulate matter and surface coatings in natural waters

Solid phases, such as surface coatings （SC）, suspended particulate matter （SPM） and deposited sediments （DS）, contribute to the pool of heavy metals in natural waters. Their existing and forming conditions lead to potential differences in enrichment capacity of pollutants, chemical compositions and crystals. In this study, the contents of heavy metals in SC, SPM and DS were determined by GF-AAS after digestion with a mixture of concentrated HNO3 and HClO4. The selective extraction method was employed to remove Fe, Mn oxides and organic matters and associated heavy metals （Cu, Pb, Zn）. X-ray diffraction analyses were performed to characterize the crystals in the samples. The results showed that no significant difference in the contents of Fe-oxides in DS, SPM and SC was found, but the contents of Mn-oxides and organic matter follow the order of SC〉SPM〉DS. The significant crystal characters were observed in DS, SPM and SC, and the kinds of minerals and crystallization degree follow the order of DS〉SC〉SPM. In addition, quartz was the most important matter of crystals in the solid phases. Enrichment capacity follows the order of SPM〉SC〉DS for Pb, Cu and Zn. Organic matter was the major sorbent for Cu, and Mn oxides and organic matter played an important role in the enrichment of Zn. However, Pb was absorbed mainly by Fe oxides. Moreover, compared with Fe oxides and organic matter, Mn oxides had a great enrichment capacity for these metals. Although DS, SPM and SC were formed in the same water system, contents of chemical components, crystals and enrichment capacities to heavy metals were obviously different.     

Speciation and potential remobilization of heavy metals in sediments of the Taihu Lake, China

The species of Cu, Pb, Zn, Cd and Cr in sediments of the Taihu Lake, China, have been analyzed using the sequential chemical extraction method. Variations in the chemical fractions of these metals and their geographic distributions have also been studied. For all five metals, the residual fraction is highest but the exchangeable fraction is lowest among all the fractions. Compared to other metals, Cd has the highest percentage in the exchangeable fraction, and Cr is associated mainly with the residual fraction. Cu in the organic fraction and Pb in the Fe-Mn fraction are the important species, whereas the lowest percentages are found for Cd in the organic fraction, Cu in the Fe-Mn oxide fraction and Pb in the carbonate fraction. With respect to spatial differences, the total contents in the non-residual fractions of the metals in bay sediments are found to be higher than those in other sediments. The fractions of Cd, Cu and Cr showed significant variations in different regions. The fractions of Pb and Zn, however, did not show significant variations in spatial distribution, suggesting different amounts and different paths of anthropogenic input for the metals. Comparisons of the metal speciation indicated that Cd might be the most bioavailable metal, followed by Pb.     

Bioavailability of heavy metals in urban particles

Urban particles, as one of the toxic air pollutants, are important issues concerning air quality and public health, especially in large cities like Guangzhou （China）. Toxicological studies implicated heavy metals （particularly water-soluble metals） as a health hazard of particles. Once absorbed into human lung tissues, heavy metals are likely released from the particles and do harm to human body even in low concentrations. Thus, evaluating the bioavailability of heavy metals in urban particles is quite necessary. The particle samples used in this study were collected from a building roof in Guangzhou. Three different methods, sequential extraction procedure and two leaching tests, were employed to investigate the bioavailability of heavy metals in the particles. The sequential extraction scheme is specific for analyzing the chemical speciation of metals in particles, which consists of four fractions： F1： soluble and exchangeable metals; F2： carbonates, oxides and reducible metals; F3： bound to organic matter, oxidisable and sulphidic metals; and F4： residual metals. Leaching tests, GB 5086.2-1997 and TCLP, are standard methods developed by China-EPA and US-EPA and widely used in evaluating the toxicity of solid wastes. They were applied to gain additional information about more easily mobilized form of metal. Heavy metals in extraction solution, including Cu, Zn, Pb, Cd, Cr, and Ni, were analyzed by ICP-MS. According to the data from the total concentration analysis, the relative contents of 6 heavy metals in particles follow the order of Pb〉Zn〉Cu〉Cr〉Ni〉Cd. The results of sequential extraction showed that more than 50% of Cu, Zn and Cd were distributed in the F1, F2, and F3. This indicated that the bioavailability of Cu, Zn and Cd in the particles is much higher than that of Pb, Cr, and Ni. Leaching tests revealed that the concentrations of heavy metals in leachate are relatively lower than the regulatory level. The results of TCLP are much higher than those of GB 5086.2-1997, mainly due to the low pH value of the extraction fluid.     

Relationship between heavy metals and clay mineralogy of the modern sediment of salt marsh at the east coast of Wadden Sea, Denmark

Salt marshes play a significant roll in the marine and coast ecological systems. They can function as a sink for pollutants that would otherwise be harmful to the environment. Our investigation is mainly focused on clay mineralogy of the salt marsh sediment, metal associations in the environment of the modern （centennial） salt marsh sediment and possible relation between these metal associations and clay minerals involved. The studied salt marsh is located in the Skalingen Peninsula, West Denmark. About 85 percent of the deposited materials, including the heavy metals, was imported from the North Sea while only a small quantity of the materials was transported through the Varde River whose mouth is located about 10 km from the salt marsh, at the opposite side of the lagoon. A 25 cm high monolithic profile of the salt marsh sediment was collected and was cut into 1-cm slices. The rate of sediment accumulation, detailed grain size distribution, clay mineralogy, dating of the profile （^210Pb and ^137Cs）, content of organic matter as well as 17 metals： K, Ca, Ti, Mn, Fe, V, Cr, Co, Ni, Cu, Zn, Br, Rb, Sr, Y, Zr, Nb were investigated. Principal components and factor analyses demonstrated strong positive loadings for most of the studied metals, fine grain fractions as well as organic matter, indicating a close relation among these components. Mn, Fe, Ni, Cu, Zn, Rb were found best correlated to the clay fraction （〈2 microns）, which comprises primarily illite, kaolinite, minor chlorite and lesser smectite/illite mixed layer.     

Trace metal geochemistry of core sediments between Visakhaptanam and Kakinada, along the eastcoast of India

Six sediment core samples collected from the innershelf of the east coast of India between Visakhapatnam and Kakinada were analyzed for major （Al ＆ Fe） and trace metals （Cu, Co, Ni, Cd, Pb, Zn, Mn ＆ Cr） to study the processes that regulate their concentrations in coastal sediments and to evaluate the metal contamination due to anthropogenic interference. High concentrations of Fe （5%-7%） are attributed mainly to the fine texture and its proximity to the source, maflc rocks. Positive correlation of Fe with Mn in all the cores indicates the influence of early diagenetic process. Positive correlations between Co, Ni, Zn and Cd among themselves and with Fe indicate their adsorption to ferromanganese oxides and involvement in geochemical processes. Further normalization of metals to Al indicates that the sediments are depleted in Mn ＆ Zn and relatively enriched in Cd, Co, Ni, Pb ＆ Cr, which also confirms that the origin of these sediments is of geological rather than biogenic importance. The Geo-accumulation （Igeo） values calculated for Ni, Pb, Co, Cd, Zn ＆ Cr are more or less near to unity （Igeo≥1）, indicating no industrial metal pollution. Pollution Load Index （PLI） values （1-2） calculated for the trace metals confirm the above findings.     

Mineralogy, geochemistry and release of heavy metals in wastes from indigenous zinc smelting in Northwest Guizhou

Environmental impact resulting from mining activities is serious and ubiquitous all over the world, and it has become one of the important aspects in environmental geochemistry. The environment was seriously damaged by wastes from historical zinc smelting in Northwest Guizhou. The geochemical distributions of Pb and Zn in the different grain-size fractions of wastes indicate that the coarser particles show similar or even higher heavy metal concentrations than finer ones in the samples, although the concentrations of heavy metals tend generally to increase as the size fractions get finer. The heavy metal contents are very high, with maximum values of 31631, 57178, 2367 and 311.5 mg/kg for Pb, Zn, Cu and Cd, respectively. It is also shown that the residual fraction of Pb is less than that of Zn, accounting for 0.39%-15.75% and 14.3%-46.2%, respectively, of the total, and this is likely relative to Zn-silicate minerals formed from smelting. Although the relative partitioning of Pb and Zn is very low （0.03%- 1.3.% for Pb; 0.03% -3.3% for Zn）, the exchangeable fraction of the waste contains large amounts of heavy metals （1.5%-385 μg/g for Pb; 3-590 μg/g for Zn）. Heavy metals in exchangeable forms have the highest solubility to give the highest potential bioavailability in contrast to other chemical forms. Mineralogical study indicates that the wastes were found to be highly heterogeneous materials, dominated by quartz, feldspar, carbonatite, iron or/and aluminum vitric compounds and a few secondary mineral phases, and their contents vary with the type of smelting wastes. The secondary minerals formed from smelting and sequentially weathering are the major chemical phase for heavy metals. Complex composition of many phases and substitution of elements suggested that many of the phases were found to be non-stoichiometric compounds. Pb was found to be the main Pb phase in the wastes by precipitation or/and adsorption.     

The Compositions of Six Chinese Ordinary Chondrites and Element Distributions in Their Different Phases

Six Chinese ordinary chondrites (four of them have fallen in recent years and the trace element abundances have not yet been reported for the other two) were examined.The contents of 21 elements (Na,Cr,Mn,Sc,Se,Zn,Br,Ni,Fe,Co,Ir,Cu,Ga,As,Au,Sb,Os,W,Re,Pt,and Ru)in the magnetic fractions and 20 elements (Na,K,Ca,Sc,Cr,Mn,Fe,Co,Ni,Zn,Se,Br,La,Sm,Eu,Yb,Lu,Ir,Au,and As) in the non-magnetic fractions were de-termined by INAA. The results indicate that the 5 H-group chondrites show almost no difference in composition,but they are different from the Zhaodong L-group chondrite in elemental abundance.As a normalized element(relative to CI),the concentrations of Ga in the magnetic fractions can be used to classify ordinary chondrites(H-,L- and LL-group).The bulk composition and modal weight of each component calculated from element concentrations in different phases are in good agreement with the bulk rock analyses presented in the literature.     

Heavy metal concentrations in water and surface sediments of Maharlou Lake, SE of Shiraz, Iran

The main objective of this study is to evaluate trace metal distribution and identify their sources in the Maharlou Lake. Trace metals （Cr, Co, Ni, Cu, Zn, Cd, Pb） and major elements （A1, Ca, Fe, K, Mg, Mn, Na, P） were investigated in water and surface sediments. There was a negative relationship between the depth of water and heavy metal concentration. Metal concentrations in water and sediment samples show a high variability and decrease in this order： Al〉Fe〉Ni〉Co〉Pb〉Zn〉Cu〉Mn〉Cd. In the northern parts of the lake, especially at the inflow of drains and the Khoshk River of Shiraz City, metal concentrations are higher in both water and sediment samples. In order to assess the heavy metal enrichment in sediment samples, trace metal concentrations were normalized for Al. Except for Mn, all metals are enriched relative to average crust and average sedimentary rocks. Also, the results showed that stations located at the northern coast of the lake, have higher enrichment factors （EF） than the other stations. The results of this study showed that the Khoshk River and other drains are the main pollutant sources of the Maharluo Lake.     

Visible and near infrared reflectance spectroscopy for measuring soil heavy metal content as a quick method

Conventional methods for investigating soil heavy metal contamination based on raster sampling and chemical analysis are time consuming and relatively expensive. Reflectance spectroscopy within the visible-near-infrared （VNIR） region is known for being rapid, convenient, and accurate. Due to low abundance, heavy metals in soils cannot exhibit their inherently spectral features. The objective of this study were （1） to examine the possibility of reflectance spectra as a rapid method to assess Ni, Cr, Cu, Hg, Zn, As, Pb, and Cd in soils, and （2） to explore the mechanism by which to predict spectrally featureless heavy metals. Two research areas located in the south （120 samples） and north （61 samples） of Nanjing City were researched. Reflectance spectra of the samples were recorded on a Perkin-Elmer Lambda 900 spectrophotometer. Partial least-square regression （PLSR） approach was used to develop calibration equations between the spectral data and measured values for heavy metals. The prediction results of the two areas were consistent. Except for Cd all the other elements could be successfully predicted using the reflectance spectra. The prediction accuracy for Ni, Cr, and Cu was highest, while that for Hg and Cd was lowest. In order to further explore the physicochemical mechanism behind the relations between reflectance spectra and heavy metals, one more principal component analysis （PCA） was done for nine elements （eight heavy metals and Fe）. The results of PCA for the both areas were also consistent. Loading plot of factors 1 and 2 from the results of PCA showed that Ni, Cr and Cu, the prediction accuracy of which was highest, were clustered together with Fe. For the other elements that were less correlated with Fe, their prediction accuracy was also lower than that of the three elements. Fe is spectrally active and can exhibit its absorption features. Therefore, the inter-correlation between heavy metals and spectrally active total Fe is the major mechanism by which to predict spectrally featureless trace metals. This study for the two areas showed the potential of reflectance spectra to predict microelements in soils.     

Fine-particle Mn and other metals linked to the introduction of MMT into gasoline in Sydney, Australia： Results of a natural experiment

PM2.5 particulates were analyzed using accelerator-based ion beam methods for a suite of 21 species （H, C, Na, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Br, Pb） to evaluate the contribution to Sydney air associated with the introduction of MMT as a replacement for Pb. MMT was discontinued in 2004. Teflon filters continuously sampled for 7 years from 1998 to 2004 were analyzed from two sites： a suburb （Mascot） close to the Central Business District [CBD （n=718）] and a high trafficked area, and a relatively rural （background） setting, ～20 km west of the CBD （n=730）. Mean Mn concentrations in air at the background site increased from 1.5- 1.6 ng/m^3 to 〈2 ng/m^3 at the time of the greatest MMT use whereas those at Mascot increased from about 2 to 5 ng/m^3. From the maximum values, the Mn showed a steady decrease at both sites concomitant with the decreasing use of MMT. Lead concentrations in air at both sites decreased from 1998 onwards, concomitant with the phase out of leaded gasoline in 2002. A high correlation was obtained for the relationship between Mn in air and lead replacement gasoline （LRG） use （R2 0.83） and an improved correlation for Mn/Al＋Si＋K and LRG use （R2 0.93）. With Mn concentrations normalized to background values of Al＋Si＋K to account for the lithogenically-derived Mn, the proportion of anthropogenic Mn was -70%. Changes for Mn and Pb in the particulates are attributed to the before-during-after use of MMT and decreasing use of Pb in gasoline.     

Distribution and sequential extraction of some heavy metals in urban soils of Guiyang City,China

Sixty-two soil samples collected from different functional zones of Guiyang were analyzed for total concentrations and sequential extraction of Cr, Cu, Pb, Zn and Cd by ICP spectrometry. The average total concentrations ofCr, Cu, Pb, Zn and Cd in the soils of Guiyang were 92.9, 51.6, 44.1,139.3 and 0.28 mg/kg, respectively. The soils have been polluted by Cr, Cu, Pb, Zn and Cd to some extent in comparison with the background values of Guiyang. Significant differences were recognized in the concentrations of Cr, Cu, Pb, Zn and Cd in different functional zones. As for the sequential extraction, Cr, Cu and Zn were present mainly in the residual fraction, and Pb was present mainly in the oxidizable fraction. The reducible fraction of Cd accounts for 47.5%, and the residual fraction is lowest. The mobility and bioavailability of heavy metals follow the order of Cd〉Pb〉Cu〉Cr〉Zn.     

Heavy metal contamination in the sediment of the Second Songhua River

The Second Songhua River was subjected to a large amount of untreated effluent from petrochemical industries in Jilin City in the 1960s to the 1970s. The objectives of this study were to investigate the mercury and other heavy metal contamination in the sediment of the river. The river bottom sediment was sampled from the river segment between Jilin City to Haerbin City in 2005. Total concentrations of Hg, Cd, Cu, Cr, Pb, Zn, Ni, As, Sc, and major cations （A1, Fe, Mg, Ca, K, Na） in the sediment were measured by atomic fluorescence spectrometer, ICP-MS, and ICP-OES, respectively, following digestion with various acids. We found the concentrations of most elements in the uncontaminated sediment were significantly correlated to those of Sc.     

Enrichment of heavy metals in coal gangue by puff balls and mechanism research

Coal gangue with/without wild puff balls growing on or covering up were analyzed by means of inductively coupled plasma atomic emission spectrometry （ICP-AES） and atomic fluorescence spectrometry （AFS） to detect the contents of heavy metal elements in the plants. Seven heavy metals were chosen to do the experiments, which showed that the puffballs have strong enrichment capacity for heavy metals （As, Pb, Mn and Ni）. The highest enrichment level was Mn, 220.3 mg/kg （dry weight） for puffball fruiting bodies, and the highest As, Cr and Pb enrichment levels for puffball mycelium were 111,265.3 and 86 mg/kg, respectively. Cd, Mn and Ni could transfer from puffball mycelium to its fruiting bodies, while As, Cr, Pb and Co mainly accumulated in the mycelium. The contents of five organic acids （tartaric acid, glycolic acid, lactic acid, citric acid and malic acid） in puffballs were determined with high performance liquid chromatography. With water, ethanol and ethyl acetate as solvents, the puffball extracts performed dissolution reactions with coal gangue, in which the water extract （containing a large amount of organic acids） was most effective in releasing heavy metals, especially As, Pb, Cr, Mn, Co and Ni from coal gangue. As a pioneer species, puff balls absorbed the hazardous trace elements in coal gangue matrix to reduce its eco-toxicity, on the other hand, it raised the pH value of coal gangue, improving the vegetation growing conditions for coal gangue matrix to a certain extent and laying the foundation for ecological restoration of coal gangue dumps.     

Lead isotope and trace metal characteristics of particulates accumulated on vehicular tunnel ceilings in Hong Kong and Guangzhou, SE China

Ever-increasing accumulation of trace metals in the environment is a serious health concern. This is a valid apprehension particularly in urban settings where the population and the level of trace metal contamination are increasing rapidly. Hong Kong and Guangzhou are the most populated cities in the region of the Pearl River Delta, the fastest growing economic region in the world. In unconfined urban compartments, particulates deposited on the earth surface such as road dusts and gully sediments are good indicators to assess the level of trace metal contamination. In such locations, however, source partitioning of the pollution, which is essential to assess and then reduce the potential environmental risk, is a difficult task. This is mainly due to the complexity and variability of site-specific natural and anthropogenic conditions. This leads us to focus on the particulates accumulated in relatively confined settings, such as vehicular tunnels. Our recent studies demonstrated that particulates accumulated on the ceiling of tunnels are useful to characterize particulates mainly derived from traffic related activities. With this in mind, Pb isotope ratios and trace metal contents of the ceiling dusts from the Cross-Harbor Tunnel （CHT） in Hong Kong and the Pearl River Tunnel （PRT） in Guangzhou were characterized and compared with each other in order to evaluate the environmental impact of traffic derived inorganic pollutants in the region. The ceiling dusts from both tunnels were dominated by silt-sized particles （〈63 μm） which are significantly freer than those of road dusts, usually larger than （〉200 μm）. In general, Cr, Ni, Pb and especially Cu contents of the ceiling dusts from CHT were noticeably higher than those from PRT. This was partly attributed to longer residence time of particulates in CHT, which has been operating since 1976, while the PRT was open to public in 1996. On the other hand, Co, Fe, Mn and Zn contents of the ceiling dusts from CHT were similar to those from PRT, while Ca and Mg contents were noticeably lower.     

XANES analysis of the mechanisms of arsenic removal in biological iron and manganese treatment unit

Biological iron and manganese removal utilizing indigenous iron and manganese oxidizing bacteria （IRB hereafter） in groundwater can also be applied to arsenic removal according to our pilot-scale test. The arsenic removal probably occurred through sorption and complexation of arsenic to iron and manganese oxides formed by enzymic action of IRB. We investigated the chemical properties of iron and manganese oxides in IRB floc and the valence state of arsenic sorbed to the floc to clarify the mechanisms of the arsenic [especially As （Ⅲ）] removal. The floc samples were collected from two drinking water plants using IRB （Jyoyo and Yamatokoriyama, Japan）, and our pilot - scale test site where arsenic and iron removal using IRB is under way （Mukoh, Japan）. The Jyoyo and Yamatokoriyama IRB floc samples were subjected to As （Ⅲ） and As（Ⅴ） sorption experiments. The elemental composition of the floc samples was measured. XANES spectra were collected on As, Fe and Mn K-edges at synchrotron radiation facility Spring 8 （Hyogo, Japan）. FT-IR and the X-ray diffraction spectra of the samples were also obtained. The IRB floc contained ca. 35 % Fe, 0.3%-3.5% Mn and 2%-6% P. The samples were highly amorphous and contained ferrihidrites and hydrated iron phosphate. According to XANES analyses of IRB, As associated with IRB was in ＋5 valence state when As （Ⅲ） （or As （Ⅴ）） was added in laboratory sorption test, Fe in ＋3 valence state, and Mn a mixture of＋3 and ＋4 valence states. Small shift was observed in the XANES spectra of IRB on As K-edge as the equilibration time of the sorption experiment was increased. Gradual oxidation of a small amount of As （Ⅲ） associated with IRB or change in arsenic binding with sorption site were the probable mechanism.     

Environmental impacts from mining at Taojiang Mn ore deposit, central Hunan, China

The Taojiang Mn ore deposit was exploited in the early 1960s, and waste rocks were developed since then. Because the Mn ores were hosted within the metal-enriched black shales （Peng et al., 2004）, the continuous mining has led to the exposure of an immense quality of black shales, which might cause serious impacts on environments. The present study deals with this environmental issue with samples from the waste rocks, and from the surrounding soils and surface water. The mineralogy of the waste rock was studied using EMPA, then a large number of elements in all waste rock, soil, and water samples were analyzed at a wide range of concentrations with high accuracy using an Elan6000 ICP-MS machine at Guangzhou Institute of Geochemistry, Chinese Academy of Sciences. The waste rock is composed mostly of black shales, with minor Mn carbonates. Both black shales and Mn carbonates of the waste rock contain many sulfide minerals, mainly pyrite, with minor galena, sphalerite, chalcopyrite, and others. The waste rocks are enriched in many metals including Sc, V, Cr, Co, Ni, Fe, Mn, Cu, Zn, Pb, Th, U, Mo, Sb, Sn, Tl, and others, and the metals are mostly hosted within the sulfides. Weathering of waste rocks might cause emission of the following metals： V, Cd, Ni, Th, U, Mo, Sb, Tl, Sc, Cr, Cu, Zn, Sn, and minor Co, and Pb. The surrounding soils are highly enriched in Cr, Co, Cu, Zn, Mn, Mo, Cd, Tl, and Pb, with the enrichment factors of 2.67.3.8, 7.26, 7.27, 8.2, 5.7, 13, and 5.4, respectively. The element ratios （Rb/Cs, Fe/Mn, Nb/Zr, Hf/Zr, and Ba/Sr） and REE distribution patterns of the soils are similar to those of the waste rocks and bedrocks.     

Research on natural plants in the lead/zinc mine in northwestern Guizhou Province

A study of soils and four flourish plants in the heavy metal polluted area by lead/zinc mine in northwestem Guizhou Province. In this study four plants were collected, the species were： Sambucus Chinensis Linn, lxeris gracilis （DC.） stebb, Buddlej daxidii Franch.ex.sinarum lmp. and Senecio scandens. The fractions of heavy metals in the soil were distinguished by the short sequential extraction procedure （I. Maiz, 1997）, the available fractions and residual fractions of heavy metals in the soil could be separated. The plant digestion was effected by means of the microwave digest system （Durali Mendil, 2004）. In each step Pb, Zn and Cd were analyzed by FAAS. This study analyzed the heavy metals （Pb, Zn, Cd） contents of the soil and plant. It is found that the contents in the plant increased linearly with heavy metal concentrations in soil. The concentrations of Pb, Zn, Cd in the four plants follow the order of Zn〉Pb〉Cd. Sambucus Chinensis Linn and lxeris gracilis （DC.） stebb were proved to have good metal-enrichment and transport ability for heavy metals in the soil.     

Occurrence and migration of hazardous trace elements in coals from Guizhou Province, China

Coals from Guizhou Province, Southwest China, attract many researchers＇ attention for their high concentrations of hazardous trace elements, sulphur and mineral components. Trace elements in coals have diverse modes of occurrence that will greatly influence their migration in the process of coal preparation. Mode of occurrence is also important in determining the partitioning during coal combustion. The coal floatation test by progressive release was used to study the migration of trace elements and mineral components in the process of froth floatation. Inductively coupled plasma mass spectrometry （ICP-MS） was used to determine the absolute concentrations of trace elements including As, Be, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, Sb, Se, Th, U, V and Zn in the parent coals and the floatation fractions. Precise determination of the mineral matter percentage in coals was obtained by low-temperature ashing. The mineral compositions in coals were quantified using Rietveld-based X-ray diffraction analysis package on low-temperature ash. Scanning electron microscope equipped with energy dispersive X-ray detector was used to provide information on the forms of occurrence of mineral components in coal. Five floatation fractions were obtained from the pulverized coal samples. The contents of trace elements and mineral components decrease from the first tailings to the last cleaned coal. The concentrations of trace elements and mineral components in parent coals and different floatation samples show that trace elements and mineral components are mainly concentrated in the first tailings samples. Nearly 60% of mineral components are enriched in the first tailings, whereas less than 1.3% remains in the cleaned coal. The ratio of sixteen trace elements concentrations in the first tailings to the corresponding concentrations in the cleaned coal ranges from 1.6 to 22.7. Quantitative mineralogical analysis results using the full-profile general structure analysis system （GSAS） showed that the main compositions of LTA include quartz, calcite, kaolinite, pyrite, chlorite, montmorillonite, illite, anatase and pyrite.