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991.
Unraveling the size distributions of surface properties for purple soil and yellow soil 总被引:1,自引:0,他引:1
Soils contain diverse colloidal particles whose properties are pertinent to ecological and human health, whereas few investigations systematically analyze the surface properties of these particles. The objective of this study was to elucidate the surface properties of particles within targeted size ranges(i.e. 10, 1–10, 0.5–1, 0.2–0.5 and 0.2 μm) for a purple soil(Entisol) and a yellow soil(Ultisol) using the combined determination method. The mineralogy of corresponding particle-size fractions was determined by X-ray diffraction.We found that up to 80% of the specific surface area and 85% of the surface charge of the entire soil came from colloidal-sized particles( 1 μm), and almost half of the specific surface area and surface charge came from the smallest particles( 0.2 μm). Vermiculite,illite, montmorillonite and mica dominated in the colloidal-sized particles, of which the smallest particles had the highest proportion of vermiculite and montmorillonite. For a given size fraction, the purple soil had a larger specific surface area, stronger electrostatic field, and higher surface charge than the yellow soil due to differences in mineralogy.Likewise, the differences in surface properties among the various particle-size fractions can also be ascribed to mineralogy. Our results indicated that soil surface properties were essentially determined by the colloidal-sized particles, and the 0.2 μm nanoparticles made the largest contribution to soil properties. The composition of clay minerals within the diverse particle-size fractions could fully explain the size distributions of surface properties. 相似文献
992.
Effects of aeration method and aeration rate on greenhouse gas emissions during composting of pig feces in pilot scale 总被引:8,自引:0,他引:8
The aim of this study was to uncover ways to mitigate greenhouse gas(GHG) emissions and reduce energy consumption during the composting process. We assessed the effects of different aeration rates(0, 0.18, 0.36, and 0.54 L/(kg dry matter(dm)·min)) and methods(continuous and intermittent) on GHG emissions. Pig feces and corn stalks were mixed at a ratio of 7:1. The composting process lasted for 10 weeks, and the compost was turned approximately every 2 weeks. Results showed that both aeration rate and method significantly affected GHG emissions. Higher aeration rates increased NH3 and N2O losses,but reduced CH4 emissions. The exception is that the CH4 emission of the passive aeration treatment was lower than that of the low aeration rate treatment. Without forced aeration,the CH4 diffusion rates in the center of the piles were very low and part of the CH4 was oxidized in the surface layer. Intermittent aeration reduced NH3 and CH4 losses, but significantly increased N2 O production during the maturing periods. Intermittent aeration increased the nitrification/denitrification alternation and thus enhanced the N2 O production. Forced aeration treatments had higher GHG emission rates than the passive aeration treatment. Forced aeration accelerated the maturing process, but could not improve the quality of the end product. Compared with continuous aeration, intermittent aeration could increase the O2 supply efficiency and reduced the total GHG emission by 17.8%, and this reduction increased to 47.4% when composting was ended after 36 days. 相似文献
993.
Uranium-reducing bacteria were immobilized with sodium alginate, anthraquinone-2,6-disulfonate(AQDS), and carbon nanotubes(CNTs). The effects of different AQDS-CNTs contents, U(Ⅳ) concentrations, and metal ions on U(Ⅳ) reduction by immobilized beads were examined. Over 97.5% U(Ⅵ)(20 mg/L) was removed in 8 hr when the beads were added to 0.7% AQDS-CNTs, which was higher than that without AQDS-CNTs. This result may be attributed to the enhanced electron transfer by AQDS and CNTs. The reduction of U(Ⅵ) occurred at initial U(Ⅵ) concentrations of 10 to 100 mg/L and increased with increasing AQDS-CNT content from 0.1% to 1%. The presence of Fe(Ⅲ), Cu(Ⅱ) and Mn(Ⅱ)slightly increased U(Ⅵ) reduction, whereas Cr(Ⅵ), Ni(Ⅱ), Pb(Ⅱ), and Zn(Ⅱ) significantly inhibited U(Ⅵ) reduction. After eight successive incubation-washing cycles or 8 hr of retention time(HRT) for 48 hr of continuous operation, the removal efficiency of uranium was above 90% and 92%, respectively. The results indicate that the AQDS-CNT/AL/cell beads are suitable for the treatment of uranium-containing wastewaters. 相似文献
994.
放射源在线监控管理系统的应用探讨 总被引:1,自引:0,他引:1
为进一步强化放射源全程动态管理,提升核与辐射科学监管水平,放射源在线监控管理系统被作为一种有效手段得以广泛应用。以扬州市为例,介绍了该系统构成和功能要求,从科学化、实用化方向对系统在实际应用中存在的突出问题逐一分析并提出了"一企一策,多措并举"的解决办法。事实验证放射源在线监控管理系统的应用必须结合企业实际情况和监管实际要求不断改进,才能提升核与辐射环境监管工作的信息化水平,加强辐射污染事件的快速反应能力,有效降低放射源丢失、盗窃事故的发生率。 相似文献
995.
不利的地理气象条件,产业、能源结构不合理,汽车尾气超标排放,城市扬尘严重,法规不健全及群众环保意识薄弱导致了河北省连续出现大范围、重污染、持续时间长的雾霾天气。为此,河北省采取了削减煤炭消费、产业结构转型升级、控制机动车污染、加强区域联防联控等治理措施。目前河北省治污仍面临着结构调整、经济方式转变历时长,资金和环境科技支撑能力不足,人员安置难等困难,建议通过实施京津冀生态文明建设一体化规划,借鉴欧美发达国家的先进经验,争取更多资源和资金支持来进一步提升治理效果。 相似文献
996.
Liu Yuanyuan Gao Fengyu Yi Honghong Yang Chen Zhang Runcao Zhou Yuansong Tang Xiaolong 《Environmental science and pollution research international》2021,28(3):2549-2571
Environmental Science and Pollution Research - Nitric oxides (NOx, which mainly include more than 90% NO) are one of the major air pollutants leading to a series of environmental problems, such as... 相似文献
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