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排序方式: 共有1442条查询结果,搜索用时 156 毫秒
161.
Chuanliang Fu Long Chen Boling Li Zhipeng Wu Qingjie Zhao Qiuyue Wang Hailong Wang Bhupinder Pal Singh Weidong Wu 《环境科学学报(英文版)》2022,34(11):77-89
This work was to study composition characteristics and the subsequent effect on the lead (Pb) binding properties of dissolved organic matter (DOM) derived from seaweed-based (SWOF) and chicken manure organic fertilizers (CMOF) during a one-year field incubation experiment using the excitation-emission matrix-parallel factor (EEM-PARAFAC) and two-dimensional correlation spectroscopy (2DCOS) analysis. Results showed that high aromatic and hydrophobic fluorescent substances were enriched in CMOF-derived DOM and SWOF-derived DOM and enhanced over time. And phenolic groups in the fulvic-like substances for SWOF-derived DOM and carboxyl groups in the humic-like substances for CMOF-derived DOM had the fastest responses over time, respectively. Moreover, both non-fluorescent polysaccharides and fluorescent humic-like substances or fulvic-like substances with aromatic (C=C) groups first participated in the binding process of Pb to SWOF-derived DOM on day 0 and 180 during the lead binding process. In contrast, humic-like substances associated with aromatic (C=C) and phenolic groups gave a faster response to Pb binding on day 360. Regarding CMOF-derived DOM, the fulvic-like substances associated with aromatic (C=C) and carboxylic groups displayed a faster response to Pb ions on day 0. Nonetheless, polysaccharides and humic-like associated with phenolic groups had a faster response on days 180 and 360. It is noteworthy that the polysaccharides, which participated in Pb binding to CMOF-derived DOM, posed a higher risk of Pb in the environment after 360 days. Therefore, these findings gave new insights into the long-term applications of commercial organic fertilizers for the amendment of soil. 相似文献
162.
Vapor wall losses can affect the yields of secondary organic aerosol. The effects of surface-to-volume (S/V) ratio and relative humidity (RH) on the vapor-wall interactions were investigated in this study. The oxygenated volatile organic compounds (OVOCs) were generated from toluene-H2O2 irradiations. The average gas to wall loss rate constant (kgw) of OVOCs in a 400 L reactor (S/V = 7.5 m−1) is 2.47 (2.41 under humid conditions) times higher than that in a 5000 L reactor (S/V = 3.6 m−1) under dry conditions. In contrast, the average desorption rate constant (kwg) of OVOCs in 400 L reactor is only 1.37 (1.20 under humid conditions) times higher than that in 5000 L reactor under dry conditions. It shows that increasing the S/V ratio can promote the wall losses of OVOCs. By contrast, the RH effect on kgw is not prominent. The average kgw value under humid conditions is almost the same as under dry conditions in the 400 L (5000 L) reactor. However, increasing RH can decrease the desorption rates. The average kwg value under dry conditions is 1.45 (1.27) times higher than that under humid conditions in the 400 L (5000 L) reactor. The high RH can increase the partitioning equilibrium timescales and enhance the wall losses of OVOCs. 相似文献
163.
164.
Miscanthus for Renewable Energy Generation: European Union Experience and Projections for Illinois 总被引:1,自引:0,他引:1
Heaton Emily A. Long Stephen P. Voigt Thomas B. Jones Michael B. Clifton-Brown John 《Mitigation and Adaptation Strategies for Global Change》2004,9(4):433-451
Mitigation and Adaptation Strategies for Global Change - 相似文献
165.
Wan Kailiang Long Wenjun 《中国人口.资源与环境(英文版)》2007,5(4):42-48
The issue of agricultural insurance subsidy is discussed in this paper aiming to make it provided more rationally and scientifically. It is started with the connection between agricultural insurance and financial subsidy. It is really necessary and crucial to implement the financial insurance due to the bad operational performance, especially in the developing countries. But the subsidy should be provided more rationally because financial subsidy has lots of negative effects. A model in competitive insurance markets developed by Ahsan et al (1982) and a farmers' decision model are developed to solve the optimal subsidized rate. Finally, the equation is got to calculate it. But a quantitative subsidized rate is not made here because the calculation should be under some restricted conditions, which are always absent in the developing countries. So the government should provide some subsidy for the ex ante research and preparation to get the scientific probability and premium rate. 相似文献
166.
Jilai Gong Long Chen Guangming Zeng Fei Long Jiuhua Deng Qiuya Niu Xun He 《环境科学学报(英文版)》2012,24(7):1165-1173
This study describes a new effective adsorbent for cadmium removal from aqueous solution synthesized by coating a shellac layer, a natural biodegradable and renewable resin with abundant hydroxyl and carboxylic groups, on the surface of iron oxide magnetic nanoparticles. Transmission Electron Microscopy (TEM) imaging showed shellac-coated magnetic nanoparticle (SCMN) adsorbents had a core-shell structure with a core of 20 nm and shell of 5 nm. Fourier Transform Infrared Spectroscopic analysis suggested the occurrence of reaction between carboxyl groups on the SCMN adsorbent surface and cadmium ions in aqueous solution. Kinetic data were well described by pseudo second-order model and adsorption isotherms were fitted with both Langmuir and Freundlich models with maximum adsorption capacity of 18.80 mg/g. SCMN adsorbents provided a favorable adsorption capacity under high salinity conditions, and cadmium could easily be desorbed using mild organic acid solutions at low concentration. 相似文献
167.
描述了散货码头粉尘污染现状,分析比较了几种常用的积尘清扫方法。为了有效清扫散货码头的积尘,提出采用集中式真空吸尘系统。文章从系统形式、水力计算方法和工程实例等方面简单介绍了集中式真空吸尘系统。印尼Paiton燃煤电厂码头工程设计采用了集中式真空吸尘系统进行积尘清扫,工程建成投产一年多来,积尘清扫效果明显,有效地降低了粉尘污染。实例说明,真空吸尘是解决散货码头积尘清扫问题较为有效的方式。 相似文献
168.
采用中心聚类、M-K检验等方法,以内蒙古地区为例,利用全球Pacific Decadal Oscillation(PDO)、Multivariate ENSO Index(MEI)等大空间尺度数据以及内蒙古及其周边70个气象站1951~2016年平均最低气温、平均气温、平均最高气温、风速、大气压等站点数据,定性、定量揭示变暖停滞的变化特征及其对影响因子变化的响应.结果表明:研究区各分区3类气温在1981~1993年间发生升温突变,此后1998~2008年间陆续发生变暖停滞.不同类型气温在不同分区与各影响因子的相关性优劣有所不同,如平均最低气温与AMO、PDO、MEI、太阳总辐射、风速、大气压的相关性最好,平均气温次之,平均最高气温最差;西部区气温与AMO、PDO、MEI、太阳总辐射相关性较好,中部区气温则与AMO、风速相关性较好等.整体上,1990s~2000s,随各分区AMO上升驱缓、PDO处于正位相阶段但呈下降趋势或处于负位相时、MEI值与太阳总辐射下降、风速、大气压、相对湿度的持续下降/上升及之后的趋势转变,各分区气温发生变暖停滞,如当AMO开始整体进入上升趋缓阶段,风速持续减小8~13a,倾向率达到-0.26~-0.11m/(s·10a)时,平均气温发生变暖停滞.平均最低气温对3类影响因子变化的响应最敏感,平均气温次之.气温变暖停滞是多种影响因子共同作用的结果.本研究丰富了该方面研究成果,对气候变化研究及防灾减灾等有一定借鉴意义. 相似文献
169.
目的研究在机体两侧螺旋桨声波干涉状态下,机体假件表面的降噪效果。方法通过模拟双螺旋浆在机体两侧的分布结构,以壳体结构模拟机身壁板,两侧对称布置电机驱动的螺旋桨旋转台,搭建双桨干涉试验平台,控制螺旋桨运行状态,测量机身表面声压级分布,得到螺旋桨旋转平面内机身外表面的声压级分布规律。通过对比单桨运行状态与双桨干涉状态测点的声压级,验证双桨干涉对机体的降噪效果。结果双桨干涉具有明显的降噪效果,尤其是机体45°方向测点降噪效果最明显。与单桨运行状态相比,双桨对消状态下,最大降噪量为1.84 dB,靠近螺旋桨旋转中心测点(0°测点)声压级降低1.58 dB,机体最上方测点(90°)噪声略有上升,声压级增加0.29dB。结论双桨同时运行状态下,降低了机体表面一定区域的声压级,且对其余区域声压级增加较小,通过控制双桨运行状态能达到降噪的目的。 相似文献
170.
基于大田试验的铅镉复合污染土壤中甜糯玉米低积累特性 总被引:1,自引:0,他引:1
为筛选适合在铅(Pb)、镉(Cd)复合污染土壤种植的低积累特性甜糯玉米品种,选取39个玉米品种,通过大田试验,研究其籽粒和秸秆对Pb和Cd的富集特性和差异.将玉米产量、富集系数和基于土壤Pb和Cd风险阈值的方法作为筛选低积累玉米品种的评价指标.结果表明,不同品种玉米的产量、籽粒和秸秆的Pb和Cd含量之间存在显著差异(P<0.05).籽粒对Pb和Cd的富集系数分别为0.00003~0.00230和0.01~0.15,秸秆对Pb和Cd的富集系数分别为0.003~0.065和0.64~4.28.通过对不同玉米富集系数的聚类分析,综合不同品种玉米的土壤Pb和Cd风险阈值得出,惠甜5号、新美甜818和玉糯9号可在Pb和Cd含量超风险管制值的耕地安全生产,天贵糯937和金萬糯2000可在Cd含量超风险筛选值的耕地安全生产.惠甜5号、新美甜818和玉糯9号作为Pb和Cd复合低积累品种,适宜在广西铅镉复合污染土壤上推广种植,天贵糯937和金萬糯2000作为籽粒低积累、秸秆Cd高积累品种,建议将其作为植物修复资源加以利用. 相似文献