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991.
Tu Chuang Mu Xianzhong Wu Yufeng Gu Yifan Hu Guangwen 《Environment, Development and Sustainability》2022,24(8):10089-10117
Environment, Development and Sustainability - The undergoing rapid urbanization is bringing dramatic economic development and social improvement for cities, but also a series of problems associated... 相似文献
992.
993.
Mingqiang Huang Weijun Zhang Xuejun Gu Changjin Hu Weixiong Zhao Zhenya Wang Li Fang 《环境科学学报(英文版)》2012,24(5):860-864
Secondary organic aerosol (SOA) formed from Cl-initiated oxidation of toluene was investigated in a home-made smog chamber. The size distribution and chemical composition of SOA particles were measured using aerodynamic particle sizer spectrometer and the aerosol laser time-of-flight mass spectrometer (ALTOFMS), respectively. According to a large number of single aerosol diameter and mass spectra, the size distribution and chemical composition of SOA were obtained statistically. Experimental results showed that SOA particles created by Cl-initiated oxidation of toluene is predominantly in the form of fine particles, which have diameters less than 2.5 m (i.e., PM2.5), and glyoxal, benzaldehyde, benzyl alcohol, benzoquinone, benzoic acid, benzyl hydroperoxide and benzyl methyl nitrate are the major products components in the SOA. The possible reaction mechanisms leading to these products are also proposed. 相似文献
994.
LUCC是影响陆地植被碳循环的重要因子之一。采用2000、2005和2009年3期遥感影像解译及运用GIS技术提取芜湖市2000-2009年的土地利用变化数据,根据前人对植被NPP的研究成果,计算芜湖市土地利用变化对生态系统中植被碳储量的影响。结果表明:在2000-2005年,耕地大量转化为林地、草地大量转化为耕地等使其植被碳储量净增加了4.43×103~22.14×103t;2005年-2009年,林地大量的转移为耕地、建筑用地,耕地转为水域、建设用地等使其植被碳储量净减少了72.34×103~289.38×103t。研究结果显示,芜湖市植被碳储量总体呈减少趋势,且林地是影响芜湖市植被碳储量的主要因素。 相似文献
995.
996.
Zhiming Gu Quanyuan Cai Yan Liu Fengsheng Li 《Journal of Polymers and the Environment》2013,21(2):479-486
The electrochemical degradation of chitosan using Ti/Sb–SnO2 electrode was studied in this work. The experimental results showed that as a non-active electrode with high oxygen potential, Ti/Sb–SnO2 electrode had a good efficiency for degrading chitosan. The kinetic behavior of electrochemical degradation of chitosan using Ti/Sb–SnO2 electrode and the function relationship between experimental parameters and degradation rate constant were also investigated. The kinetic analysis revealed that this electrochemical process using Ti/Sb–SnO2 electrode obeyed the zeroth–order reaction kinetics under the experimental conditions examined. The degradation rate constant at Ti/Sb–SnO2 electrode had the linear relationship with 1.13 power of current density, ?1.36 power of initial concentration of chitosan and 0.19 power of concentration of acetic acid, The temperature dependences of the degradation rate constant could be expressed by the Arrhenius equation. The concentration of sodium acetate had a negligible influence on the degradation rate constant. 相似文献
997.
Effects of Wood Fiber and Microclay on the Performance of Soy Based Polyurethane Foams 总被引:1,自引:0,他引:1
Various polyurethane (PU) foams were prepared by in situ reaction of isocyanate and soy-based polyol. The effects of wood fiber and microclay on the foam morphologies, mechanical properties and thermal behaviors of PU foams were investigated. NCO index had fundamental impacts on the influences of wood fiber and microclay on the performance of PU foams. The reinforcement behavior of flexible foams was different to that of both semi-rigid and rigid foams. Both fiber and microclay improved the compressive strength at a high NCO index of 140–250, and contributed to relative high decomposition temperatures. Unlike the compressive strength, the tensile strength was decreased due to the amount of hard polyurea formation from secondary reactions at the highest NCO level. In addition, wood fiber had different reinforcement mechanism from microclay. Wood fiber desired to form chemical bonds during foaming while microclay had potential to form physical insertions. This difference was expressed by the change of their thermal degradation temperature. 相似文献
998.
The P concentration in Norton Creek which drains cultivated Histosols in Quebec showed median concentration exceeding up to 14 times the environmental guideline of 0.03 mg total P L(-1). The aim of this study was to develop environmental and agronomic thresholds using soil tests to provide a tool for P management in Histosols. Soil samples were collected from Histosols across Quebec (82) and in fertilizer trials (66) to calibrate soil test methods against the degree of P saturation (DPS(OX)) using the acid-oxalate method and setting alpha(m) = 0.4, and the water-extractable P (P(W)) (Sissingh, 1971). The field trials on crop response to added P were conducted with carrots (8), potatoes (11), onions (10), Chinese cabbage (7), celery (10), and lettuce (20). Relative yields were computed as yield in control without P divided by highest yield with added P. The Mehlich III (M-III) P extraction was more closely related (r(2) = 0.73) to DPS(OX) than the Bray 1 method (r(2) = 0.62) and the Florida extraction method (r(2) = 0.53). The [P/(Al+gammaFe)](M-III) ratio as index of P saturation (IPS(M-III)) was the most closely related to DPS(OX) (r(2) = 0.88) setting gamma = 5. The critical [P/(Al+5Fe)](M-III) ratio of 0.05 at DPS(OX) = 0.25 and P(W) = 9.7 mg P L(-1) was validated by an independent study from North Carolina. The soil group (low- vs. high-IPS(M-III) soils) significantly influenced crop response to added P. Critical agronomic IPS(M-III) values were found between 0.10 and 0.15. Those environmental and agronomic benchmarks are instrumental for managing the P in vegetable-grown Histosols. 相似文献
1000.
Xu G Wang Q Gu Q Cao Y DU X Li F 《Journal of environmental science and health. Part. B》2006,41(2):189-199
Low-density polyethylene (LDPE) film residues left in farmlands due to agricultural activities were extensively investigated to evaluate the present pollution situation by selecting the typical areas with LDPE film application, including Harbin, Baoding, and Handan of China. The survey results demonstrated that the film residues were ubiquitous within the investigated areas and the amount reached 2,400-8,200 g ha(-1). Breakage rates of the film residues were almost at the same level in the studied fields. There were relatively small amounts of film residues remaining in neighboring farmland fields without application of LDPE film. The studies showed that the sheets of LDPE residues had the same oxidative deterioration, which was probably due to photodegradation instead of biodegradation. The higher molecular weight components of the LDPE film gradually decreased, which were reflected by the appearance of some small flakes detached from the film bodies. LDPE films in the investigated fields gradually deteriorated and the decomposing levels developed with their left time increasing. The degradation behaviors of LDPE films were confirmed by using Fourier transform infrared (FTIR), scanning electron microscopic (SEM), and gel permeation chromatography analyses. 相似文献