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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.

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.

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..

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.

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.

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