CAS Institute of Geochemistry

Kunming, China

CAS Institute of Geochemistry

Kunming, China
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Sh T.,CAS Institute of Geochemistry | Liu C.-Q.,CAS Institute of Geochemistry | Feng C.,Guizhou Institute of Crop Genetic Resources
Journal of Geochemical Exploration | Year: 2012

Antimony (Sb) occurs in the environment both naturally and anthropogenically. Numerous activities cause its anthropogenic accumulation and the release is mainly into the terrestrial environment. Therefore, it is crucial to investigate the fate of Sb in soils at the smelting sites where its deposition is often very high and the land needs to be cleaned up. However, little is known regarding the sorption behavior of environmentally found Sb oxidized states in the soils with different characteristics and compositions. The present study examined solubility and toxicity of Sb from the soils polluted due to the smelting operations. An inhibition of seed growth was used as an indicator of the toxic effect of Sb. Batch adsorption experiments were conducted over the pH range of 3-7 and in different equilibrium concentrations of Sb (III) as a form of the smelter release. The water soluble proportion of Sb was low (0.70-1.63%) compared to its deposition in the surface soils; however, extracted amounts caused a slightly reduced germination rate of wheat seeds with a lighter weight. Nevertheless, the soil soluble Sb concentration did not produce severe toxicity symptoms in the growth of roots and sprouts of the germinated seeds. The effects of Sb (III) and (V) forms were slightly different at the level of 5mg·L -1. In Sb (III) solution the smaller elongation of both sprouts and roots was observed as compared to the control samples while in Sb (V) solution only sprout lengths were shorter. Distribution coefficient (K d) of Sb in soil water system was estimated to be 56mL·g -1 at pH values of 3 and 10-17mL·g -1 at pH of 6-7. Thus, neutral pH increases Sb mobility and its translocation to the plants that should be accounted of in agricultural production and remediation activities. © 2012 Elsevier B.V.

Wang D.,Xiamen University | Zhao Z.,CAS Institute of Geochemistry | Dai M.,Xiamen University
Marine Pollution Bulletin | Year: 2014

This study examined the Pb content and Pb isotopic composition in a sediment core taken from the East China Sea (ECS) shelf, and it was observed that since 2003 the increasing anthropogenic Pb inputs have impacted as far as the ECS shelf sediments. The ECS shelf sediments were generally characterized with low bulk Pb contents (12.5-15.0. μg/g) and relatively lithogenic Pb isotopic signatures (both HCl-leached and residual fractions). However, elevated Pb records along with lighter Pb isotopic signals have occurred in the post-2003 sediments, as a result of a small but increasing anthropogenic Pb contribution from the heavily human perturbed coastal sediments due to the sharply increasing coal consumption in mainland China since 2003. © 2013 Elsevier Ltd.

Sh T.,CAS Institute of Geochemistry | Liu C.-Q.,CAS Institute of Geochemistry | Wang L.,CAS Shanghai Institute of Applied Physics
Microchemical Journal | Year: 2012

This current study examined the fate of antimony (Sb) in the soil environment and its association with soil humic acid (HA). It is anticipated that a significant proportion of Sb is retained in soil organic layer; therefore, the oxidation state of Sb is controlled by the soil HA to some extent which influences Sb solubility and ecotoxicity. Parent HA material as well as prepared HA-Sb (III) composites was investigated by determining elemental composition and by performing nuclear magnetic resonance (NMR) and X-ray absorption fine structure (XAFS) spectroscopy study in order to study Sb coordination to natural macro organic ligand. The Sb (III) binding to soil derived HA mainly contributed to its open chains through carboxyl and hydroxyl moieties as revealed by the 1H and solid state 13C NMR spectroscopy. The protons in carboxylic and hydroxylic groups (those proton signals are characteristic of HAs with different origins) disappeared in the HA-Sb composite; and relative changes were observed in aliphatic proton distribution between the HA samples with and without Sb. The overall patterns of 13C NMR spectra for the investigated samples were analogous to each other; moreover, it was estimated that the cyclic structure of the HA nucleus remained unchanged during Sb (III) association. Based on the absorption edge energy and coordination numbers, Sb oxidation state in a native soil was interpreted as pentavalent, meanwhile the HA-Sb composite contained both Sb (III) and Sb (V). It was shown that HA catalyzes Sb (III) oxidation to Sb (V) but the process was relatively slow. However, XAFS spectra sensitivity was limited when studying the HA-Sb composite that was prepared from the isolated soil HA fraction, so only data on the first shell Sb-O coordination were interpreted. © 2012 Elsevier B.V..

Peng T.,Chinese Academy of science | Peng T.,University of Chinese Academy of Sciences | Peng T.,CAS Institute of Geochemistry | Wang S.-J.,Chinese Academy of science | Wang S.-J.,CAS Institute of Geochemistry
Catena | Year: 2012

Surface runoff and soil loss from 2007 to 2010 related to land use and rainfall regimes in karst hill slopes in Guizhou Province, southwest China, were analyzed. Using the hierarchical clustering method, sixty-one rainfall events under the subtropical monsoon climate condition were classified into 5 types of rainfall regimes according to the depth, maximum 30-min intensity, and duration of rainfall. In our study, we first demonstrated that the amounts of surface runoff and soil loss on the karst hill slopes were very small compared to the non-karst areas, because the dual hydrological structure in the karst region, including ground and underground drainage systems, could influence the processes of rainfall recharge and runoff generation. Most rainfall water was transported underground through limestone fissures and fractures, while little was in the form of surface runoff. Second, the runoff and soil loss were affected by land use management and vegetation cover. Soil loss was intensified in a descending order to five types of land uses: pastureland>burned area>cropland>combination vegetation land>young forestland. Third, the runoff and soil loss exhibited remarkable variances among different rainfall regimes. Large runoff and soil loss were mainly created by heavy rainfall storms with a rainfall depth of more than 40mm and a maximum 30-min rainfall intensity of over 30mmh -1. In addition, rainfall storms with large antecedent precipitations could also produce large runoff and soil loss. These observations indicated that limestone fissures and fractures play important roles in surface runoff generation on karst limestone slopes due to their large storage capacity and high infiltration rate. Lastly, the soil erosion risk in the karst pure limestone slope is quite high and should be paid particular attention, especially in regards to over-grazing because the soil loss created by a single heavy rainstorm in pastureland was 5 times the annual soil loss tolerance. © 2011 Elsevier B.V.

Fan H.,CAS Institute of Geochemistry | Fan H.,Chinese Academy of Geological Sciences | Wen H.,CAS Institute of Geochemistry | Zhu X.,Chinese Academy of Geological Sciences | And 2 more authors.
Precambrian Research | Year: 2013

Abundant bedded chert deposits occurred at the Ediacaran-Cambrian transition interval at the Yangtze Platform, South China. However, there is not a non-controversial and integrated model for the origin of these chert deposits from trace element patterns and oxygen isotopic evidence. To understand the origin and the oceanic environment of these chert deposits, we analyzed the Si isotopic composition, major and trace elements of chert samples from two stratigraphically correlated sections with a depositional age around 542Ma. The relationship between Al2O3 content and Si isotopic values indicated three end-member sources of Si derivation. The most negative δ30Si values (-0.3‰ to -0.5‰) reflect the silicon derived from hydrothermal fluids due to intense tectonic activity. The most positive δ30Si values (up to +1.2‰) could reflect the increase of 30Si in the hydrothermal fluid by precipitation, or the signature of seawater. The medium δ30Si value (+0.2‰ to +0.7‰) could be interpreted as the mixing of the hydrothermal fluid and volcanic materials with negative δ30Si and ambient seawater with positive δ30Si. It is obvious that the injection of Si-rich hydrothermal fluid would affect the δ30Si and trace element distribution of seawater. In addition, we estimated that the δ30Si values of Ediacaran-Cambrian transitional seawater range from +2.2‰ to +3.5‰ based on assumed fractionation factors -2.3‰

Zhao M.,CAS Institute of Geochemistry | Zeng C.,CAS Institute of Geochemistry | Zeng C.,Chinese Academy of Geological Sciences | Liu Z.,CAS Institute of Geochemistry | And 2 more authors.
Journal of Hydrology | Year: 2010

Rainfall, spring stage, water temperature, pH and conductivity in the paired karst spring catchments of Chenqi and Dengzhanhe, which shared the same climatic condition but different land use/land cover (LULC) at Puding, Guizhou Province, SW China, were monitored by two high-resolution multi-parameter auto-recordable instrument of CTDP300 during the hydrological year of September 2007-September 2008. Other monthly hydrogeochemical and carbon isotopic (δ13C) variations in the paired karst catchments during the same hydrological year were also investigated. A thermodynamic model was used to link the continuous data to monthly hydrogeochemical data allowing the calculation of CO2 partial pressure (pCO2) and calcite saturation index (SIc) on a continuous basis. The primary study objective was to understand how the karst processes and karst hydrogeochemistry respond to different LULC, which is essential to assessing the karst-related carbon cycle. Marked seasonal and storm-scale variations were found for pH, conductivity, pCO2, SIc and δ13C of the two springs, indicating that both springs were dynamic and variable systems. However, there were differences in the magnitude and direction of the variations of these features between the two springs. The higher pCO2 and HCO- 3 concentration and lower pH, SIc and δ13C in Chenqi spring than those in Dengzhanhe spring tend to be related to the difference in LULC between Chenqi and Dengzhanhe spring catchments: in the Chenqi spring catchment, there was larger soil cover and the paddy land was located in the discharge area, both of which produced and kept more CO2 (a major driving agent for the karst processes) and lower δ13C in the soil-aquifer system, while in the Dengzhanhe spring catchment area, there was larger bare carbonate rock occurrence and the paddy land was located mainly in the recharge area. Moreover, the pH increased and pCO2 decreased generally in Chenqi spring after rainfall, possibly due to more carbonate dissolution in the larger soil cover rich in limestone fragments in the spring catchment, while the pH decreased and pCO2 increased generally in Dengzhanhe spring after rainfall. All these differences show that soil cover and land use pattern played important roles in the karst processes. In other words, the karst hydrogeochemistry and the karst-related carbon cycle could be regulated effectively by different LULC. In addition, the higher concentrations of Ca2+, SO2/4, Mg2+ and conductivity of Dengzhanhe spring were due to the dissolution of more gypsum and dolomite minerals in the strata of Dengzhanhe spring catchment. Therefore, the karst hydrogeochemical parameters, including pH, conductivity, HCO- 3, Ca2+, Mg2+, SO2- 4, pCO2, SIc, and δ13CDIC, could serve as good indicators of different LULC and the other environmental changes. © 2010 Elsevier B.V. All rights reserved.

Pang X.,CAS Institute of Geochemistry | Pang X.,University of York | Lee X.,CAS Institute of Geochemistry
Atmospheric Environment | Year: 2010

Carbonyl compounds in urban ambient air and street canyons were measured from December 2008 to August 2009 in a mountainous city in southwest China (Guiyang). The formaldehyde yield from the photo-oxidation of isoprene emitted by vegetation was estimated to be in the range of 0.63-3.62 μg m-3 from May to August, which accounted for 28.8-33.4% of ambient formaldehyde. Based on the calculation of photolysis rates and rates of reaction with the OH radical, it was found that photolysis was the predominant sink for formaldehyde and acetone in both summer and winter. For acetaldehyde, photo-oxidation by OH radicals and photolysis were the major sinks in summer while photo-oxidation by OH radicals was the dominant sink in winter. Wet precipitation was found to be an important removal process for the atmospheric carbonyls. In the urban ambient air, the average concentrations of formaldehyde, acetaldehyde, acetone and all carbonyls were 4.8 ± 2.1, 5.7 ± 3.3, 5.1 ± 2.5, and 25.1 ± 9.2 μg m-3 (n = 139), respectively. The average concentrations of these species in street canyons were 18.8 ± 6.5, 9.4 ± 3.2, 10.9 ± 2.1, and 64.1 ± 16.3 μg m-3 (n = 62), respectively. The significantly higher carbonyl levels on weekdays (compared to weekends) highlight the contribution of vehicle emissions to carbonyls in the street canyons. © 2010 Elsevier Ltd. All rights reserved.

Lu H.,CAS Institute of Geochemistry | Lu H.,University of Quebec at Chicoutimi
Acta Petrologica Sinica | Year: 2011

Most fluid inclusion trapped from a homogeneous fluid but some may trapped from a heterogeneous fluids (immiscibility process). In the nature, there are a lot of immiscible processes and systems, including immiscibility between basic magma and felsic magma, magma and hydrothermal fluids; magma and CO2 fluid; saline fluids and CO2 fluid etc. The fluid inclusions trapped from homogeneous and heterogeneous processes are with different characteristics and in somewhat is not easy to be distinguished. The immiscibility process is an important process of mineralization. Especially in the gold deposition, pegmatite formation and porphyry Cu-Mo system.

Chetelat B.,CAS Institute of Geochemistry | Liu C.-Q.,CAS Institute of Geochemistry | Wang Q.,CAS Institute of Geochemistry | Zhang G.,CAS Institute of Geochemistry
Chemical Geology | Year: 2013

We present major and trace element data in suspended particulate matter (SPM) collected in the Changjiang main channel and its tributaries. Suspended sediments are derived from a mafic source related to the Emeishan Large Igneous Province (ELIP) in the Upper Reach and from a more felsic source in the Middle/Lower Reaches. The difference in chemical composition between the two sources has a strong influence on the apparent weathering intensity. Although the apparent loss of soluble elements follows a climatic gradient from the Upper Reach to the Lower Reach, the co-variation of weathering indices with different proxies for igneous differentiation suggests that a lithologic control cannot be ruled out. By taking into account the variability in chemical composition of the parent rocks, we show that river suspended sediments from the upper reach may have not experienced less intense chemical weathering than those transported by rivers from the Lower/Middle Reaches characterized by higher runoff and surface temperature. We argue that the relationships observed for different indices of weathering with climate are probably an artifact and are mainly driven by the change in chemical composition of the sediment's parent-rocks. © 2013 Elsevier B.V.

Tserenpil S.,CAS Institute of Geochemistry | Liu C.-Q.,CAS Institute of Geochemistry
Microchemical Journal | Year: 2011

Soil samples were collected from an antimony smelting site in Guangxi Zhuang Autonomous Region, China, at four locations characterized by different land usage, including two cultivated sites: one formerly cultivated and one uncultivated. Surface soils from all four sites were heavily polluted by toxic metals including antimony (Sb), lead (Pb) and arsenic (As), and their concentrations were, and, respectively. In the uncultivated area metal levels were 1.4-6.2 times higher as compared to the formerly and currently agriculture land. Lower levels at the cultivated sites may have resulted from an accumulation of airborne particles by vegetation and lower contents in the surface soil. However, the elevated mercury (Hg) content may reflect both natural and anthropogenic origins in this smelting site. Soil-derived humic acid (HA) from the smelting site reacted directly with Sb (III) aqueous solutions with concentrations of 12, 71 and 143mg.g-1. The maximum Sb (III) binding to the soil-derived HA was 253-mol.g-1 (added concentration of 71mg.g-1) and showed more binding (up to 50%) at lower Sb content. © 2010 Elsevier B.V.

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