排序方式: 共有39条查询结果,搜索用时 15 毫秒
21.
YANG Yu-huan CHEN Hao~* PAN Gang State Key Laboratory of Environmental Aquatic Chemistry Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing China. 《环境科学学报(英文版)》2007,(12)
Adsorption/desorption in a new Zn(Ⅱ)-TiO_2 adsorption system was investigated at different particle concentrations(C_p).TEM,SEM and XRD analyses revealed that the TiO_2 particles were an aggregation of nano-sized(approximately 10 nm)pure anatase-type TiO_2. Adsorption experiments were carried out with particle concentrations of 100,400 and 1000 mg/L,and their adsorption isotherms were found to decline successively,showing an obvious C_p effect.Desorption experiments indicated that adsorption in this system was irreversible,and the irreversibility increased with increasing C_p.These phenomena could be explained by the MEA(metastable equilibrium adsorption)theory and the C_p effect could be modeled well with an MEA-Freundlich-type C_p effect isotherm equation. This study may help understand environmental behavior of contaminants on ultrafine natural particles. 相似文献
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IntroductionOrdosPlateauliesinthesouthwestofInnerMongoliaandbelongstoamulti playerandcomplicatedecogeographicaltransitionzone ,namely ,itisatransitionzoneofatmospherecircle ,climate ,geologyandgeography ,vegetationandnaturalbelt ,biota ,industryandculture .I… 相似文献
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LI Zhe SHEN Lin-tao HUANG Wei~* XIE Ke-chang Key Laboratory of Coal Science Technology Ministry of Education Shanxi Province Taiyuan University of Technology Taiyuan China. 《环境科学学报(英文版)》2007,19(12)
The catalyst of Fe-Mo/ZSM-5 has been found to be more active than Fe-ZSM-5 and Mo/ZSM-5 separately for selective catalytic reduction (SCR) of nitric oxide (NO) with NH_3.The kinetics of the SCR reaction in the presence of O_2 was studied in this work.The results showed that the observed reaction orders were 0.74-0.99,0.01-0.13,and 0 for NO,O_2 and NH_3 at 350-450℃,respectively. And the apparent activation energy of the SCR was 65 kJ/mol on the Fe-Mo/ZSM-5 catalyst.The SCR mechanism was also deduced. Adsorbed NO species can react directly with adsorbed ammonia species on the active sites to form N_2 and H_2O.Gaseous O_2 might serve as a reoxidizing agent for the active sites that have undergone reduction in the SCR process.It is also important to note that a certain amount of NO was decomposed directly over the Fe-Mo/ZSM-5 catalyst in the absence of NH_3. 相似文献
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针对我国水源地藻类污染日趋严重等问题,利用前期分离获得的溶藻菌Streptomyces sp.HJC-D1研究固定化微生物技术强化污染水源水除藻以及脱氮性能。结果表明,对照组和试验组的水体叶绿素a平均去除率分别为(71.66±5.35)%和(80.94±4.36)%,NH4+—N的平均去除率为(77.76±2.83)%和(72.36±3.18)%,而高锰酸盐指数(CODMn)平均去除率为(24.99±1.52)%和(18.74±1.38)%;不同曝气条件的影响研究发现,曝气/停曝时间比2:4、曝气量60 L.h-1工况下,系统CODMn和NH4+—N去除率均有所提高,相比对照组NO3-—N积累更为明显;水力停留时间(HRT)变化对系统NH4+—N、CODMn等的去除影响不大,但缩短HRT时叶绿素a去除率有所降低;分析反应器内填料表面微生物相发现,试验组填料表面有溶藻菌富集,推测对照组除藻主要通过填料对藻类的吸附去除,而试验组则是藻类吸附在填料表面后通过溶藻微生物实现藻类去除。 相似文献
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采用营养液培养法和二因素完全实验设计,在5 mg.L-1Cr(Ⅵ)、Ni复合污染条件下对22种植物进行筛选实验,选取富集量较高且生长较快的旱伞草Cyperus alternifolius,分析其对Cr(Ⅵ)、Ni的累积规律及生理生化效应。结果表明:(1)在Cr(Ⅵ)、Ni复合污染胁迫下,旱伞草生长状况良好,对铬、镍具有较高的富集能力;(2)在Cr(Ⅵ)、Ni复合污染下,Cr(Ⅵ)抑制旱伞草对Ni的吸收,Ni促进旱伞草对Cr的吸收;(3)分别在单因素Cr(Ⅵ)、Ni的胁迫下,SOD和CAT活性随着Cr(Ⅵ)、Ni质量浓度(0-50 mg.L-1)的增加都是先上升后下降,MDA总体都呈增加的趋势;(4)在Cr(Ⅵ)胁迫下,旱伞草地上部富集总铬的含量较高,但六价铬含量较低,对Cr(Ⅵ)的转化率最大可达到97.00%。研究表明,旱伞草是一种修复Cr(Ⅵ)、Ni污染很有潜力的物种。 相似文献
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生物有机肥对香蕉枯萎病及根系分泌物的影响 总被引:3,自引:0,他引:3
生物有机肥通过调节微生物群落多样性来改善土壤生态环境,而根际微生物生态环境变化取决于根系分泌物的种类和数量.研究通过盆栽试验和离位溶液培养法研究了生物有机肥对香蕉枯萎病及香蕉根系分泌物的影响.结果表明,生物有机肥对香蕉枯萎病的防病效果高于有机肥和不施肥处理,生物有机肥和有机肥防病效果分别达到55.4%和28.5%;香蕉根系分泌物中低分子量有机酸包括草酸、苹果酸和反丁烯二酸,以草酸为主,ρ(草酸)占ρ(有机酸总量)的百分比为83.6%~93.0%;生物有机肥比有机肥更显著降低香蕉根系分泌物中ρ(苹果酸)、ρ(反丁烯二酸)和ρ(有机酸总量),不同处理处理根系分泌物的ρ(有机酸)依次为:有机肥>生物有机肥>不施肥;生物有机肥处理的氨基酸种类和质量浓度最大,有机肥次之,生物有机肥处理中根系分泌物的ρ(γ-氨基丁酸)、ρ(β-丙氨酸)、ρ(a-氨基丁酸)、ρ(谷氨酸)、ρ(天冬氨酸)和ρ(磷酸丝氨酸)均显著高于有机肥和不施肥处理;生物有机肥处理的主要氨基酸[各氨基酸质量浓度占ρ(氨基酸总量)的百分比大于5%]有磷酸丝氨酸、苏氨酸、γ-氨基丁酸、乙醇氨和肌肽,其中ρ(磷酸丝氨酸)和ρ(γ-氨基丁酸)显著高于不施肥和有机肥处理;香蕉枯萎病病情指数与ρ(磷酸丝氨酸)、ρ(丝氨酸)、ρ(异亮氨酸)呈显著负相关,相关系数分别为-0.99、-0.98和-0.95,与ρ(鹅肌肽)呈极显著正相关,相关系数为1.00.生物有机肥降低了根系分泌物中有机酸的质量浓度,增加了氨基酸的种类和质量浓度,且香蕉枯萎病病情指数与根系分泌物中一些氨基酸质量浓度存在显著相关性,这可能是生物有机肥在香蕉枯萎病防治中起作用的原因之一. 相似文献
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大连市区大气氮湿沉降研究 总被引:1,自引:0,他引:1
雨水的主要成分是水并含有低浓度的含氮化合物,降落在春夏秋3季的雨水对植物生长有一定的影响.雨水除满足植物生理生态需水外,也为植物提供了一定的氮营养.确定雨水中的含氮量多少时空分布状况对植物生长状况的影响不论从环境科学还是植物生长科学都有一定的意义.通过2009—2010年对位于我国辽东半岛最南端的大连市区的雨水连续收集,利用流动分析仪测定雨水中的活性氮化合物含量及变化趋势,可能对生态环境有一定的影响.结果表明:两年的降雨次数分别为34和51次,降雨量分别为687.55和630.22 mm,介于常年年平均降雨量(550~950 mm)的范围内.雨水的总含氮量分别为22.94和41.65 kg·hm-2,总无机含氮量分别为17.67和18.67 kg·hm-2,其中,前1年铵态氮和硝态氮的通量分别为7.99和9.68 kg·hm-2;后1年铵态氮和硝态氮的通量分别为7.72和10.95 kg·hm-2,降雨量大的7和8月份氮沉降通量大,氮沉降通量的变化趋势与降雨量一致.降氮强度各月分布不均,2年的月平均值分别为0.42和0.55 mg·L-1·h-1,总氮的沉降强度按季节排序为冬季>秋季>春季>夏季.随降雨沉降的活性氮化合物可以作为植物生长的氮源,每年平均沉降的总氮相当于使用69.15 kg·hm-2的尿素.一般来说雨水中的无机氮化合物能被植物直接利用,含量多少对不同生态系统产生不同的影响;在农田生态系统有利于作物和杂草的生长,在江河湖海边缘有利于植被的生长,产生富营养化.大连市区2年的月平均降氮质量浓度为4.90 mg·L-1,已远远超出富营养水体中氮质量浓度的阈值,周边水体存在富营养化的隐患. 相似文献
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鸡粪与麦秆混合厌氧发酵环境中各因子响应关系研究 总被引:2,自引:0,他引:2
为了探究发酵过程中各因子之间的相互响应关系,以鸡粪和麦秆为发酵原料,利用Canoco4.5软件对鸡粪/麦秆不同比例混合发酵条件下不同发酵阶段内各因子进行分析,以阐明各发酵阶段内因子间的相互影响关系.结果表明:当鸡粪/麦秆以5∶5的比例混合时,能获得最佳单位甲烷产量(90.56 m L·g-1,以VS计).在整个发酵过程中甲烷产气速率表现为先升高再降低的趋势,将其根据产气速率的大小划分为3个阶段,分别为第Ⅰ阶段(预备期)、第Ⅱ阶段(高峰期)、第Ⅲ阶段(消退期).不同发酵阶段影响单位甲烷产量的主效因子有一定的差异性,其中,第Ⅱ阶段的主效因子为发酵基质的C/N,第Ⅲ阶段为p H值.各发酵阶段因子间相关性各异,第一阶段因子间相关性最强,此后相关性逐渐降低.因此,针对不同阶段各主效因子分别进行控制,能够有效提高发酵效率. 相似文献
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BI Xiao-yi WANG Peng~* JIANG Hong XU Huan-yan SHI Shu-jie HUANG Jun-li Research Center for Green Chemistry Technology School of Municipal Environmental Engineering Harbin Institute of Technology Harbin China. 《环境科学学报(英文版)》2007,(12)
The catalyst of CuO_x/Al_2O_3 was prepared by the dipping-sedimentation method usingγ-Al_2O_3 as a supporter.CuO and Cu_2O were loaded on the surface of Al_2O_3,characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS).In the presence of CuO_x/Al_2O_3,the microwave-induced chlorine dioxide(ClO_2) catalytic oxidation process was conducted for the treatment of synthetic wastewater containing 100 mg/L phenol.The factors influencing phenol removal were investigated and the results showed that microwave-induced ClO_2-CuO_x/Al_2O_3 process could effectively degrade contaminants in a short reaction time with a low oxidant dosage,extensive pH range.Under a given condition(ClO_2 concentration 80 mg/L,microwave power 50 W,contact time 5 min,catalyst dosage 50 g/L,pH 9),phenol removal percentage approached 92.24%,corresponding to 79.13% of COD_(Cr) removal.The removal of phenol by microwave-induced ClO_2-CuO_x/Al_2O_3 catalytic oxidation process was a complicated non-homogeneous solid/water reaction, which fitted pseudo-first-order by kinetics.Compared with traditional ClO_2 oxidation,ClO_2 catalytic oxidation and microwave-induced ClO_2 oxidation,microwave-induced ClO_2 catalytic oxidation system could significantly enhance the degradation efficiency.It provides an effective technology for the removal of phenol wastewater. 相似文献
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