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Shikang TAO Xinning WANG Hong CHEN Xin YANG Mei LI Lei LI Zhen ZHOU 《Frontiers of Environmental Science & Engineering》2011,5(3):391-401
ATSI Model 3800 aerosol time-of-flight mass spectrometer (ATOFMS) was deployed for single-particle analysis in Shanghai during the World Exposition (EXPO), 2010. Measurements on two extreme cases: polluted day (1st May) and clean day (25th September) were compared to show how meteorological conditions affected the concentration and composition of ambient aerosols. Mass spectra of 90496 and 50407 particles were analyzed respectively during the two sampling periods. The ART-2a neural network algorithm was applied to sort the collected particles. Seven major classes of particles were obtained: dust, sea salt, industrial, biomass burning, organic carbon (OC), elementary carbon (EC), and NH4-rich particles. Number concentration of ambient aerosols showed a strong anti-correlation with the boundary layer height variation. The external mixing states of aerosols were quite different during two sampling periods because of different air parcel trajectories. Number fraction of biomass burning particles (43.3%) during polluted episode was much higher than that (21.6%) of clean time. Air parcels from the East China Sea on clean day diluted local pollutant concentration and increased the portion of sea salt particle dramatically (13.3%). The large contribution of biomass burning particles in both cases might be an indication of a constant regional background of biomass burning emission. Mass spectrum analysis showed that chemical compositions and internal mixing states of almost all the particle types were more complicate during polluted episode compared with those observed in clean time. Strong nitrate signals in the mass spectra suggested that most of the particles collected on polluted day had gone through some aging processes before reaching the sampling site. 相似文献
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Siqi Zhang Furui He Xiuqin Fang Xinyu Zhao Yuanyuan Liu Gaobo Yu Yang Zhou Yuhong Feng Jiacheng Li 《环境科学学报(英文版)》2022,34(3):55-63
Soil aggregation plays an important role in agricultural production activities. However, the structure of soil aggregation is destroyed by the natural environment and unreasonable farming management, resulting in the loss of water, fertilizers and pesticides in soil. At present, hydrogels have been widely reported to promote the formation of soil aggregation. In this paper, amphiphilic calcium alginate (ASA/Ca2+) was applied to promote the formation of soil aggregation and enhance pesticide retention. Initially, an ASA was obtained through the one-pot Ugi condensation (a four-component green chemical reaction). Then, ASA/Ca2+ hydrogel is prepared by Ca2+ cross-linking. The formation of soil aggregation was determined through the Turbiscan Lab Expert stability analyzer, Confocal Laser Scanning Microscope (CLSM), and Transmission Electron Microscope (TEM). And the effect of soil aggregation on acetamiprid environmental behavior was investigated by adsorption kinetics, adsorption isotherms, and leaching. The results shown that the three-dimensional network structure of ASA/Ca2+ hydrogel can promote the formation of soil aggregation. Aggregate durability index (ADI) was 0.55 in the presence of ASA/Ca2+ hydrogel, indicating that amphiphilic hydrogel can enhance the stability of soil aggregation. The adsorbing capacity of acetamiprid was 1.58 times higher than pure soil, and the release of acetamiprid only about 20% in the presence of ASA/Ca2+ hydrogel. These results would be helpful for the formation of soil aggregation and pesticides adsorption on soil aggregation. Thus, ASA/Ca2+ hydrogel is likely to improve soil quality, simultaneously it can minimize the mobility of pesticides in the agricultural system. 相似文献
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Weiguo Shen Gejin Gan Rui Dong Hu Chen Yu Tan Mingkai Zhou 《Journal of Material Cycles and Waste Management》2012,14(3):228-233
The utilization of the phosphogypsum (PG) as cement retarder is both an economical and an ecological approach to treat this solid waste. Cement using raw PG as retarder has two problems pressing for solution,namely, delaying the setting time and difficulty being fed into the cement mill. The soluble phosphates in PG behave as super-retarder and bring about retarding in the setting process of cement made with PG. Two types of solidified phosphogypsum (SPG) were prepared to solve those two problems. The strength and the water stability of the SPG were good enough to ensure that they may be conveyed easily and fed into the cement mill stably. The cements with SPG had a similar setting time and strength as cement made with natural gypsum (NG). The microstructure of two kinds of SPG were observed with SEM. During factory application of SPG, good techniques and economic benefits were obtained. 相似文献
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为改善聚合物材料的火灾安全性,利用二硫化钼(MoS2)的独特性能,结合纳米复合、催化成炭等设计思路,采用共沉淀法制备CeMnOx-MoS2和CeFeOx-MoS2双金属氧化物-MoS2纳米杂化物,并将其分别应用到2种典型聚合物(聚氨酯和环氧树脂)中.结果 表明:2种杂化物均匀分散在聚合物基体中,可有效延缓聚合物材料的热... 相似文献