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Zhang C.,Southwest University | Zhang C.,Chongqing Key Laboratory of Agricultural Resources and Environment | Zhang Y.-H.,Southwest University | Wang Y.-M.,Southwest University | And 5 more authors.
Huanjing Kexue/Environmental Science | Year: 2017

Four typical coal-fired power plants in Chongqing, representing two different boiler types (circulating fluidized bed boiler and pulverized coal boiler), were chosen to investigate mercury emission characteristics through a mercury mass balance method by analyzing mercury contents in all input and output raw materials in order to accurately estimate mercury emissions. The results showed coal with mercury concentrations ranging (80.77±6.39)-(266.83±4.71) μg·kg-1 could be a significant contributor of input mercury in these four studied power plants. Most mercury output from these power plants entered into solid waste with high proportion of mercury entering the fly ash in CFB plants and entering the fly ash and desulfurization gypsum in PC plants. Mercury removal efficiencies of studied plants were in the range of 72.89%-96.05%, and these efficiencies in CFB plants were higher than those in PC plants. The mercury emission factors for EFelectricity and EFcoal of these four plants were 4.66-29.47 μg·(kW·h)-1and 8.55-71.77 mg·t-1, respectively. The mercury emission was also calculated to be 6.13-429.17 g·d-1. Mercury emissions from coal-fired power plants were associated with the content of mercury in coal, boiler type, generation load, pollution control equipment, and so on. To control the mercury emissions, more attention should be paid to improving the generation load, increasing the mercury removal efficiency of flue gas cleaning equipment, and strengthening the supervision of solid waste re-utilization. © 2017, Science Press. All right reserved.


Zhang C.,Southwest University | Zhang C.,Chongqing Key Laboratory of Agricultural Resources and Environment | Wang Y.,Southwest University | Zhang Z.,Southwest University | And 5 more authors.
Journal of Residuals Science and Technology | Year: 2015

A systematic survey of heavy metals and As concentrations in vegetables and soil in Chongqing was carried out to assess their potential health risks to local people. The results indicated that the Cr, Cd, Pb and As levels in some vegetables exceeded the Chinese safety standard of pollutants in food. The total carcinogenic risks of the heavy metals and As in 10 kinds of vegetables were all over the standard limits provided by USEPA and ICRP. Therefore, great attention should be paid to the issues of the heavy metals and As pollution in vegetables and the corresponding soil. © 2015 DEStech Publications, Inc.


Zhang Y.-H.,Southwest University | Zhang C.,Southwest University | Zhang C.,Chongqing Key Laboratory of Agricultural Resources and Environment | Wang D.-Y.,Southwest University | And 4 more authors.
Huanjing Kexue/Environmental Science | Year: 2015

To preliminarily discuss the mercury emission characteristics and its mass balance in each process of the iron and steel production, a typical iron and steel enterprise was chosen to study the total mercury in all employed materials and estimate the input and output of mercury during the steel production process. The results showed that the mercury concentrations of input materials in each technology ranged 2.93-159.11 μg·kg-1 with the highest level observed in ore used in blast furnace, followed by coal of sintering and blast furnace. The mercury concentrations of output materials ranged 3.09-18.13 μg·kg-1 and the mercury concentration of dust was the highest, followed by converter slag. The mercury input and the output in the coking plant were 1346.74 g·d-1±36.95 g·d-1 and 177.42 g·d-1±13.73 g·d-1, respectively. In coking process, mercury mainly came from the burning of coking coal. The sintering process was the biggest contributor for mercury input during the iron and steel production with the mercury input of 1075.27 g·d-1±60.89 g·d-1 accounting for 68.06% of the total mercury input during this production process, and the ore powder was considered as the main mercury source. For the solid output material, the output in the sintering process was 14.15 g·d-1±0.38 g·d-1, accounting for 22.61% of the total solid output. The mercury emission amount from this studied iron and steel enterprise was estimated to be 553.83 kg in 2013 with the emission factor of 0.092 g·t-1 steel production. Thus, to control the mercury emissions, iron and steel enterprises should combine with production practice, further reduce energy consumption of coking and sintering, or improve the quality of raw materials and reduce the input of mercury. © 2015, Science Press. All right reserved.


Ma T.,CAS Nanjing Institute of Soil Science | Ma T.,Hubei University of Arts and Science | Zhou L.,Chongqing Solid Wastes Management Center | Chen L.,Shanghai Research Institute of Chemical Industry | And 5 more authors.
Journal of Agricultural and Food Chemistry | Year: 2016

Excessive use of antibiotics potentially threatens human health, agricultural production, and soil phytoremediation. This arouses concern over the potential adverse effects of a commonly used antibiotic, oxytetracycline (OTC), on plants used for soil remediation and possible stimulation of antibiotic resistance genes in soils. A greenhouse experiment was conducted to investigate different rates (0, 1, 5, and 25 mg kg-1) and frequencies (one single high and daily low application) of OTC addition to soil on phytoremediation of a heavy metal contaminated soil by Sedum plumbizincicola and/or Medicago sativa (alfalfa). After 90 days both Cd and Zn were substantially removed by phytoextraction into S. plumbizincicola shoots especially at the high OTC (25 mg kg-1) treatment which also led to inhibition of antioxidative enzyme activities in both plant species. Soil microbial activity decreased significantly with the addition of OTC, and this was ameliorated by planting alfalfa and S. plumbizincicola together. OTC at <5 mg kg-1 increased the biomass of both plant species, but the frequency of OTC addition had no effect on the rate of metal removal. Alfalfa exhibited greater detoxification ability and effectiveness in soil microbial activity promotion than S. plumbizincicola with intercropping. Phytoremediation by alfalfa and S. plumbizincicola in association can both promote the removal of heavy metals and also alleviate the toxic effects of pollutants on plants and soil microbes even at relatively high soil OTC concentrations. © 2016 American Chemical Society.


Zhou X.,Southwest University | Zhang J.-Y.,Southwest University | Zhang J.-Y.,Neijiang Normal University | Wang D.-Y.,Southwest University | And 4 more authors.
Huanjing Kexue/Environmental Science | Year: 2016

Mercury removal from aqueous solutions of HgCl2 was studied by indoor simulation experiments, and the effects of three different diameter of particles of Nano-TiO2 (Nano-Titanium Dioxide) at different dosage, pH, adsorption time and the initial concentration of Hg2+ on the mercury adsorption from simulated wastewater were investigated. The single factor experiments showed that the optimal conditions were: 7.5g·L-1 of 5 nm TiO2 or 2.0g·L-1 of 100 nm TiO2, pH 8.0, initial concentration of Hg2+15 mg·L-1, adsorption time 5 min, and under these conditions the adsorption rates reached 99.5% and 99.3%, relatively. When the content of 25 nm TiO2 was 10g·L-1, and the other conditions were pH 8.0, initial concentration of Hg2+ 15mg·L-1, adsorption time 60 min, the adsorption rate was 62.8%. The Hg(II) removal effects of the TiO2 particles with different diameters followed the order of 100 nm TiO2>5 nm TiO2>25 nm TiO2. Component adsorption results showed that the 5 nm TiO2 component adsorption effect was superior to its single adsorption effect, while there was little difference between 100 nm TiO2 component adsorption effect and its single adsorption effect. The results of orthogonal experiments indicated that the influencing factors of the adsorption rate followed the order of pH>the initial concentration of Hg2+>time>dosage. The optimal experiment scheme was: pH 8.0, a dosage of 100 nm Nano-TiO2 of 2.0 g·L-1, an initial Hg2+ concentration of 25 mg·L-1 and adsorption time of 10 min. Under the experimental conditions, the maximum adsorption rate reached 99.9%, at the same time, the equilibrium concentration of Hg(II) was 0.033 mg·L-1<0.05 mg·L-1, below the current enterprise rules of water pollutants in mercury emissions limits. In addition, the maximum adsorptive capacity was 26.95 mg·g-1. The adsorption isotherm was in line with the Langmuir isotherm equation, indicating that the Hg(II) uptake by 100 nm Nano-TiO2 was typical monolayer adsorption. © 2016, Science Press. All right reserved.


Wang Y.R.,Chongqing University | Lia W.P.,Chongqing University | Liaob S.G.,Chongqing Solid Wastes Management Center
ECS Transactions | Year: 2010

In this study, electrodeposition of Pb on polycrystalline Cu surface has been investigated by cyclic voltammetry (CV). Simultaneous in real time ellipsometry (SE) have been performed to study the characterization and morphological evolution of the Pb layer. The results demonstrated that the rate at which deposition thickness is increasing is going up and revealed that thin Pb deposition layer has already acquired at all the polarization process. So the Cu substrate is not optically ignored during the total polarization process. ©The Electrochemical Society.

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