Papers by Keyword: Speciation

Abstract: Pb, Cd contamination is a serious enviroment problem in the process of exploitation and utilization of zinc mine. In this study, the contents and different fractions of Pb, Cd were investigated in a regions of zinc smelting with indigenous method. The results revealed that Pb, Cd pollution were seriously in smelting slags and farmland. The contents of Pb, Cd were 34 times and 9 times as that of the background values of soil. The sequential extraction test showed that 80% of Pb were associated with residual Pb, Fe-Mn oxides bound Pb and Organic bound Pb, while exchangeable fractions Pb was quitely lower.The sequence of Cd fracttions in slags was residual fraction>Fe-Mn oxide-bound>Exchangeable> Carbonate-bound > Organic-bound. The exchangeable fraction Cd in farmland soils was the most and reached 24%~43%. Bioavailability of Cd is very high in the studied area and had huge threat to the crop security and human healthy.

Abstract: Bosten Lake lies in semi-arid of the southern Xinjiang with hot summer, low precipitation and will be salinized and in which water plays a strategic role. The most toxicity trace metal arsenic (As) in lake sediment was taken as an object to study the environment effects when the water is increasingly salinized. Through sampling around the obviously salinity gradient area, the 191 field data were used to analyze the effect of salinity of porewater on the change of As risk to the environment. From the sample distribution between the As speciation (the As in the porewater, the exchangeable fraction and the carbonate fraction of the sedimentary As) vs. EC (salinity index), and ions concentration of Cl^-, SO₄^2-, Na⁺, Mg²⁺, K⁺ and Ca²⁺, it is inferred that the As risk is decreased when the water salinity is increasing.

Abstract: The modified Tessier method was used in the present study to analyze the antimony (Sb) speciation in suspended solids in mining wastewater from Ban-po Antimony Mine in Guizhou province. It was found that the residual fraction and the soluble fraction are the highest and the lowest in the five Sb fractions, accounting for 62.5% and 3% of the total respectively. The order of the five Sb fractions is: the residual fraction > the reduced fraction > the oxidation fraction > the acid-extractable fraction > the soluble fraction. The antimony soluble form in aqueous solution is mainly Sb (V), about 90% of the total. The results from the analysis by X-ray diffraction and scanning electron microscopy showed that the major crystalline forms of suspended solids are K-Mg-Fe-Al-Si-O-H₂O, Cu₃SbS₄, 3CaO·2Sb₂O₅·8H₂O, SiO₂ and the content of antimony element is approximately 2.55%.

Abstract: In this paper, a manual-controlled injection nanometer calcium titanate based on glass fiber filter enricher (MICTE) was prepared, and its application in speciation of Cr (III) and Cr (VI) was studied. The optimum experimental parameters for separation of the Cr (III) and Cr (VI) have been investigated. The results showed that the MICTE had adsorption capacity towards the Cr (III) and Cr (VI). And two forms of chromium show different adsorption capacities at different pH values, Cr (III) could be adsorbed at pH 9, but Cr (VI) cant be adsorbed. Whereas Cr (VI) retained at pH 3, but Cr (III) cant be adsorbed. Therefore, it is possible that the two forms of chromium are complete separated. The Cr (III) and Cr (VI) could be completely eluted with 1 mol·L¹ HCl and 1 mol·L¹NaOH, respectively. The chromium concentration was measured by atomic absorption spectroscopy. A new method for determination of the speciation of chromium in environmental water samples based on the manual-controlled injection enricher and atomic absorption spectroscopy determination was proposed. The method was successfully applied for the determination of Cr (III) and Cr (VI) in environmental waters with satisfactory results.

Abstract: Used tires were subjected to supercritical water and supercritical water with H₂O₂. The distribution of heavy metals (Pb, Mn, Ni, Cu, Zn, Cd, Cr) in used tires and the corresponding residues were analyzed. BCR sequential extraction procedure was applied to examine the speciation of heavy metals mentioned above. The results showed that: the contents of Mn, Zn, Cu, Pb, Cd increased after supercritical water treatment while that of Cr and Ni decreased significantly. The addition of H₂O₂ was beneficial for the increase of heavy metals concentration and sequestration. The sequestration rate of Mn, Zn, Cu, Pb, Cd, Cr reached to 90% after the addition of H₂O₂, and that of Ni was much lower as 40%. The main speciation of Cr and other heavy metals were in residual form and oxidate form respectively. The speciation of all heavy metals were transferred from the unstable forms of weak acid soluble and reducible to relatively stable forms of oxidizable and residual.

Abstract: The speciation of the heavy metals Cu, Cr, and Pb in surface sediment samples collected from Lugu Lake in China was analyzed by European Community Bureau of Reference (BCR) sequential extraction methods. Heavy metal bioavailability was assessed by risk assessment code. This study demonstrates that BCR sequential extraction methods and risk assessment code can be used as valuable tools to assess heavy metal mobility, bioavailability and eco-toxicity. The distribution of Cu, Cr, and Pb in the surface sediment of Lugu Lake showed that all three metals were mainly present in the reducible fraction. The bioavailability of the heavy metals in the surface sediment was in the order Cu > Cr > Pb.

Abstract: In this study, nine samples were collected along the trenches of LANJIAN mine and its water system in order to study the effect of Panzhihua Vanadium Titano-Magnetite on water during mining. Particle sizes of the sediments were analyzed with the laser, mineral composition of the sediments were analyzed with the X-ray diffraction analyzer, the content of CuPbZnHgCdAsCrCoNiMnVTiFe and the Speciation characteristics of part of them were analyzed with the atomic absorption spectrophotometer and ICP-MS. These provide a reference for the environmental governance of mine.

Abstract: The speciation of potentially toxic heavy metal elements Arsenic in waste rocks of mining activities in Xinqiao Pyrite Mine was studied by conducting improved five step sequential extraction method. The arsenic mainly existed in silicate, secondly in deoxidize, and the exchangeable, oxidizable and carbonate modes content were low. When the waste rocks reacted with the acid mine drainage, the arsenic in the deoxidize and oxidizable modes might easily release from the waste rocks. So the arsenic had high environmental risk.

Abstract: The bioavailability and environmental risk of heavy metals in soil depends greatly on their speciation, not total amounts. Different speciation analysis techniques of heavy metals in soil are reviewed and the speciation schemes are considered and discussed in some detail. The present problems remained in the field of environmental science and future trends of speciation analysis of heavy metals in soil are also briefly dealt with.

Abstract: A new method was developed for the speciation of inorganic arsenic in coal samples by liquid chromatography coupled to hydride generation atomic fluorescence spectrometry after microwave-assisted extraction. Effective extract of As(III), As(V) in coal sample was achieved by 1.0molL-1 H3PO4 and 0.1 molL-1ascorbic acid. Under the optimized conditions, the limits of detection were 0.01 ugL-1and 0.02 ugL-1for As(III), As(V). The relative standard deviation were 2.4 %, 3.3 % (c= 20.0 gL-1, n=7). The proposed method was successfully applied for the determination of speciation of inorganic arsenic in coal samples and GBW11117.