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Wang Y.,Nanjing Normal University | Wang Y.,Jiangsu Center For Collaborative Innovation In Geographical Information Resource Dev And Applied | Yang H.,Nanjing Normal University | Yang H.,Jiangsu Center For Collaborative Innovation In Geographical Information Resource Dev And Applied | And 4 more authors.
Science of the Total Environment

Natural inputs and anthropogenic influences on lakes and their catchments are reflected in the sediment record. In the present study, the extractable organic compounds from sediments in the Chaihe catchment of the Dianchi watershed were analyzed to characterize source inputs. Results show that the sediments are dominated by odd numbered n-alkanes (n-C16-n-C33), maximizing at n-C17, n-C29 and n-C31. Aliphatic hydrocarbon may be composed of terrestrial plants and bacteria. The values of δ13C27, δ13C29 and δ13C31 of n-alkanes exhibit a range from -33.27‰ to -25.46‰, from -35.76‰ to -28.47‰ and from -33.67‰ to -27.42‰, respectively and three records strongly covary with depth, falling within the range of C3 plants in the study area. An isotopic model revealed C3 plant contribution to sedimentary organic matter (OM) ranging from 40.75% to 97.22%. The values of ACL27-33, CPI27-33, OEP, Paq, Pr/Ph, (C27+C29)/2C31, (C21+C23+C25)/3C17 and nC26 -/nC27 + are consistent with the C3 plant predominance. A constant CRS model gave the accumulation rates ranging from 2.69 to 8.46mma-1 spanning 1885-2010. It was concluded that OM transport in the Chaihe catchment was influenced strongly by human activities resulting in enhanced eutrophication. © 2014 Elsevier B.V. Source

Wang J.,Nanjing Normal University | Liu Q.,Nanjing Normal University | Zhang J.,Nanjing Normal University | Zhang J.,Jiangsu Provincial Key Laboratory of Materials Cycling and Pollution Control | Cai Z.,Nanjing Normal University
Acta Agriculturae Scandinavica Section B: Soil and Plant Science

Land-use and management practices can affect soil nitrification. However, nitrifying microorganisms responsible for specific nitrification process under different land-use soils remains unknown. Thus, we investigated the relative contribution of bacteria and fungi to specific soil nitrification in different land-use soils (coniferous forest, upland fields planted with corn and rice paddy) in humid subtropical region in China. 15N dilution technique in combination with selective biomass inhibitors and C2H2 inhibition method were used to estimate the relative contribution of bacteria and fungi to heterotrophic nitrification and autotrophic nitrification in the different land-use soils in humid subtropical region. The results showed that autotrophic nitrification was the predominant nitrification process in the two agricultural soils (upland and paddy), while the nitrate production was mainly from heterotrophic nitrification in the acid forest soil. In the upland soils, streptomycin reduced autotrophic nitrification by 94%, whereas cycloheximide had no effect on autotrophic nitrification, indicating that autotrophic nitrification was mainly driven by bacteria. However, the opposite was true in another agricultural soil (paddy), indicating that fungi contributed to the oxidation of NH4 + to NO3 −. In the acid forest soil, cycloheximide, but not streptomycin, inhibited heterotrophic nitrification, demonstrating that fungi controlled the heterotrophic nitrification. The conversion of forest to agricultural soils resulted in a shift from fungi-dominated heterotrophic nitrification to bacteria- or fungi-dominated autotrophic nitrification. Our results suggest that land-use and management practices, such as the application of N fertilizer and lime, the long-term waterflooding during rice growth, straw return after harvest, and cultivation could markedly influence the relative contribution of bacteria and fungi to specific soil nitrification processes. © 2014, Taylor & Francis. Source

Zhi J.,Nanjing Normal University | Yu X.,Nanjing Normal University | Bao J.,Jiangsu Provincial Key Laboratory of Materials Cycling and Pollution Control | Jiang X.,Jiangsu Provincial Key Laboratory of Materials Cycling and Pollution Control | Yang H.,Engineering Laboratory for Energy System Process Conversion & Emission Control Technology of Jiangsu Province
Korean Journal of Chemical Engineering

Titanium dioxide (TiO2) and Mn-doped TiO2 (Mn(x)-TiO2) were synthesized in a sol-gel method and characterized by BET surface area analysis, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Gasphase elemental mercury (Hg0) oxidation and capture by the Mn-doped TiO2 catalyst was studied in the simulated flue gas in a fixed-bed reactor. The investigation of the influence of Mn loading, flue gas components (SO2, NO, O2, and H2O) showed that the Hg0 capture capability of Mn(x)-TiO2 was much higher than that of pure TiO2. The addition of Mn inhibits the grain growth of TiO2 and improves the porous structure parameters of Mn(x)-TiO2. Excellent Hg0 oxidation performance was observed with the catalyst with 10% of Mn loading ratio and 97% of Hg0 oxidation was achieved under the test condition (120 °C, N2/6%O2). The presence of O2 and NO had positive effect on the Hg0 removal efficiency, while mercury capture capacity was reduced in the presence of SO2 and H2O. XPS spectra results reveal that the mercury is mainly present in its oxidized form (HgO) in the spent catalyst and Mn4+ doped on the surface of TiO2 is partially converted into Mn3+ which indicates Mn and the lattice oxygen are involved in Hg0 oxidation reactions. © 2016 Korean Institute of Chemical Engineers, Seoul, Korea Source

Wang J.,Nanjing Normal University | Zhu B.,CAS Chengdu Institute of Mountain Hazards and Environment | Zhang J.,Nanjing Normal University | Zhang J.,Jiangsu Provincial Key Laboratory of Materials Cycling and Pollution Control | And 6 more authors.
Soil Biology and Biochemistry

In this study, a 15N tracing incubation experiment and an in situ monitoring study were combined to investigate the effects of different N fertilizer regimes on the mechanisms of soil N dynamics from a long-term repeated N application experiment. The field study was initiated in 2003 under a wheat-maize rotation system in the subtropical rain-fed purple soil region of China. The experiment included six fertilization treatments applied on an equivalent N basis (280 kg N ha-1), except for the residue only treatment which received 112 kg N ha-1: (1) UC, unfertilized control; (2) NPK, mineral fertilizer NPK; (3) OM, pig manure; (4) OM-NPK, pig manure (40% of applied N) with mineral NPK (60% of applied N); (5) RSD, crop straw; (6) RSD-NPK, crop straw (40% of applied N) with mineral NPK (60% of applied N). The results showed that long-term repeated applications of mineral or organic N fertilizer significantly stimulated soil gross N mineralization rates, which was associated with enhanced soil C and N contents following the application of N fertilizer. The crop N offtake and yield were positively correlated with gross mineralization. Gross autotrophic nitrification rates were enhanced by approximately 2.5-fold in the NPK, OM, OM-NPK, and RSD-NPK treatments, and to a lesser extent by RSD application, compared to the UC. A significant positive relationship between gross nitrification rates and cumulative N loss via interflow and runoff indicated that the mechanisms responsible for increasing N loss following long-term applications of N fertilizer were governed by the nitrification dynamics. Organic fertilizers stimulated gross ammonium (NH4 +) immobilization rates and caused a strong competition with nitrifiers for NH4 +, thus preventing a build-up of nitrate (NO3 -). Overall, in this study, we found that partial or complete substitution of NPK fertilizers with organic fertilizers can reduce N losses and maintain high crop production, except for the treatment involving application of RSD alone. Therefore, based on the N transformation dynamics observed in this study, organic fertilizers in combination with mineral fertilizer applications (i.e. OM, OM-NPK, and RSD-NPK treatments) are recommended for crop production in the subtropical rain-fed purple soils in China. © 2015 Elsevier Ltd. Source

Xiao X.,Nanjing Normal University | Xiao X.,Chongqing Technology and Business University | Sheng Z.,Nanjing Normal University | Sheng Z.,Jiangsu Provincial Key Laboratory of Materials Cycling and Pollution Control | And 4 more authors.
Catalysis Science and Technology

MnOx-CeO2/graphene (MnOx-CeO2/GR) catalysts prepared by a hydrothermal method with different mass ratios of graphene (0-0.45 wt%) were investigated for the low-temperature selective catalytic reduction (SCR) of NOx with NH3. The as-prepared catalysts have been characterized systematically to elucidate their morphological structure and surface properties by XRD, SEM, TEM, BET, XPS, H2-TPR, NH3-TPD and FT-TR. It was found that the environmentally benign MnOx-CeO2/GR (0.3 wt%) catalyst exhibited excellent NH3-SCR activity and strong resistance against H2O and SO2, which is very competitive for application in controlling NOx emission from flue gas. On the basis of the catalyst characterization, the high specific surface areas, the uniform distribution of active sites, and the interaction of manganese and cerium oxide species played key roles in the excellent catalytic performance of MnOx-CeO2/GR and resulted in improved SO2 tolerance. © The Royal Society of Chemistry 2016. Source

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