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1.
Perfluorooctane sulfonate (PFOS), as a potential persistent organic pollutant, has been widely detected in water environments, and has become a great concern in recent years. PFOS is very stable and difficult to decompose using conventional techniques. Sorption may be an attractive method to remove it from water. In this study, the molecularly imprinted polymer (MIP) adsorbents were prepared through the polymerization of 4-vinylpyridine under different preparation conditions in order to remove perfluorooctane sulfonate (PFOS) from water. The MIP adsorbents using perfluorooctanoic acid (PFOA) as the template had good imprinting effects and could selectively remove PFOS from aqueous solution. The sorption behaviors including sorption kinetics, isotherms, and effect of pH, salt, and competitive anions were investigated. Experimental results showed that the sorption of PFOS on the MIP adsorbents was very fast, pH-dependent, and highly selective. The achieved fast sorption equilibrium within 1 h was attributed to the surface sorption on the fine adsorbents. The sorption isotherms showed that the sorption selectivity of PFOS on the MIP adsorbents decreased at high PFOS concentrations, which may be due to the double-layer sorption and the formation of PFOS micelles on the sorbent surface. The sorption of PFOS on the MIP adsorbents was mainly dominated by the electrostatic interaction between the protonated vinylpyridine on the adsorbent surface and the anionic PFOS. The prepared MIP adsorbents can potentially be applied in water and wastewater treatment for selective removal of PFOS.  相似文献   

2.
膜界面探测器(membrane interface probe,MIP)是一种有机污染物的高分辨检测器,已广泛用于污染场地土壤和地下水中挥发性有机污染物污染特征与空间分布的实时原位调查检测. 当前,我国在污染场地土壤的高精度快速筛查技术和装备方面存在较大的需求,但在该领域的自主研发与应用还处于起步阶段. 本文在系统梳理MIP在国内外有机污染场地应用案例的基础上,从文献计量学的角度分析了该领域的研究现状与未来发展态势. 结果表明:自1996年首次有文献报道MIP的应用以来,该领域的发文数量呈逐年增加趋势. 当前,国际上对MIP的研究和应用较多的国家主要为美国和中国. 从已有应用案例来看,MIP主要应用于污染场地中苯系物、卤代烃、石油烃等多种污染物的原位实时检测. MIP的发展主要经历了3个阶段,分别为挥发性有机污染物传感器的研发、场地土壤及含水层污染物的测定,以及探头的联合应用. 其中,MIP与其他多功能探头的有机耦合技术及装备的研发将成为该领域未来研发的重要方向. 基于MIP在场地有机污染物检测中的局限性,并结合我国场地土壤调查的现实需求与关键科学问题,分别从阐明污染物界面传质与扩散机制、设计高性能半透膜材料、研发高精度钻测一体化装备,以及建立相关标准与技术指南等四方面,对我国污染场地土层钻进探测一体化技术与装备的研发需求与发展方向提出了展望.   相似文献   

3.
刚果红分子印迹聚合物纳米微球的合成及吸附性能   总被引:1,自引:1,他引:0  
本研究以刚果红为模板分子,α-甲基丙烯酸(MAA)为功能单体,二甲基丙烯酸乙二醇酯(EGDMA)为交联剂,乙腈为致孔剂,2,2-偶氮二异丁腈(AIBN)为引发剂,采用沉淀聚合法制备了刚果红分子印迹聚合物纳米微球(MIP).通过扫描、透射电镜对聚合物的结构和形貌进行了表征,结果显示制备的MIP微球的粒径在90 nm左右,粒径较为均匀.利用氮气吸附脱附实验测定了聚合物颗粒的比表面积和孔容.并对诸多吸附影响因素以及分子印迹聚合物的吸附能力、选择性和重复利用率进行了分析.结果表明,MIP对刚果红表现出较好的选择性识别能力,可多次循环使用,能用于染料废水中刚果红的选择性吸附.  相似文献   

4.
为了有效处理低浓度抗生素残留废水,以水热法制备的BiOBr为载体,诺氟沙星(NOR)为模板,通过表面分子印迹法制备了BiOBr分子印迹材料(MIP).同时,采用SEM与XRD对制备的材料进行相分析及显微结构分析,并利用XPS、FTIR、BET和UV-Vis DRS对所合成材料的微观结构进行观察.最后,以诺氟沙星(NOR)为目标污染物,对MIP在暗反应下的吸附性能及300 W Xe灯照射下的光催化性能进行测定,并探讨pH、投加量、初始浓度、是否印迹处理对NOR去除的影响.实验结果表明,在pH为中性,MIP投加量为2.5 g·L-1的条件下,MIP对5 mg·L-1 NOR溶液的去除率达到96.2%,且对低浓度(1 mg·L-1)NOR溶液的去除率达到99%.综合表明,本文所制备的MIP适用于低浓度诺氟沙星废水的处理.  相似文献   

5.
本文从桐柏—大别山链南缘及其前陆地区的构造变形研究入手,划分出区内两期两种型式推覆构造,即印支—燕山早期对冲式推覆构造和喜山期背冲式推覆构造。并综合分析了它们的结构,推覆方向和规模等,讨论了它的形成演化机制和油气勘探意义。  相似文献   

6.
LNAPLs污染物在层状非均质多孔介质中的运移试验研究   总被引:1,自引:0,他引:1  
文章通过室内试验研究层状非均质多孔介质中轻非水相液体(Light Non-Aqueous Phase Liquid,LNAPL)的运移机制与分布特性。首先,在二维砂槽上进行LNAPL的入渗试验,试验过程中用数码相机进行拍照,把LANPL的扩散过程以图像的形式记录下来;然后,用AutoCAD对图片进行分析处理,得出不同时刻LNAPL的入渗锋面变化图。结果发现,介质结构突变面改变了LNAPL的迁移模式。在LNAPL由中砂进入细砂层后,由于受到毛细作用的增强,其运移速度加快;而由中砂进入粗砂,受粗砂介质阻滞作用增强的影响,LNAPL运移速度变小。当LNAPL由干砂进入湿润砂体时,由于孔隙水浮托力增大,LNAPL先产生纵向运移,随后以横向迁移的形式在地下水位上部聚积。当达到一定厚度后,LNAPL的压头足以克服浮托力,驱替孔隙水进入砂土孔隙。另外,LNAPL的厚度足够大时,方可克服饱水层受到的浮托力,在地下水位上形成LNAPL池,并因孔隙水向周围砂体排泄,LNAPL池周围的水位上升。  相似文献   

7.
旅游者是乡村旅游发展中的核心要素,但当前研究缺乏从城乡空间转换中的人地关系变迁角度对旅游者进行的思考。以经历城乡生活空间重构的旅游者为研究对象,运用分析多变量交互作用的模糊集定性比较分析方法,探索旅游者乡村游憩影响因素的复杂路径。研究发现:地方情感、怀旧情感、主观规范、知觉行为控制、态度、愿望(欲望)、旅游目的地知名度形成的128种组合中,其中有8个充分性条件构型特定组合路径能够影响乡村旅游者游憩行为;单项中地方情感、怀旧情感、知觉行为控制的一致性相对较高,但都不能构成旅游者乡村游憩影响因素的必要条件;8条旅游者乡村游憩行为影响因素路径条件组合的总体覆盖率约为0.918919,总体一致性约为1,均达到了0.9的阈值标准。其中,地方情感和怀旧情感特性是最关键的影响因素;旅游者具有地方情感、怀旧情感特征时,其他影响因素都可能在“特定情境”下发挥作用。据此提出了生活空间重构旅游者的乡村游憩影响路径模型,揭示了“乡村情感—游憩意向路径”“计划行为—游憩意向路径”“游憩愿望路径”和“情感行为综合路径”四类影响路径的作用机制。旅游从业者可以据此寻找与旅游者游憩最匹配的产品开发解决方案。  相似文献   

8.
对“可耗尽自然资源”的理解-仅指有限的非生命资源还是包括生命资源在内,关涉到GATT第XX(g)条的是用范围。1947年GAAT的起草者的意图是限于非生命资源,墨西哥等发展中国家坚持GATT第XX(g)条的最初含义,WTO专家组认为第XX(g)中术语是进化的,采取有效性的条约解释原则对“可耗尽的自然资源”做出了宽广解释,包括生命资源在内。  相似文献   

9.
The movement of animals in groups is widespread in nature. Understanding this phenomenon presents an important problem in ecology with many applications that range from conservation to robotics. Underlying all group movements are interactions between individual animals and it is therefore crucial to understand the mechanisms of this social behaviour. To date, despite promising methodological developments, there are few applications to data of practical statistical techniques that inferentially investigate the extent and nature of social interactions in group movement. We address this gap by demonstrating the usefulness of a Hidden Markov Model approach to characterise individual-level social movement in published trajectory data on three-spined stickleback shoals (Gasterosteus aculeatus) and novel data on guppy shoals (Poecilia reticulata). With these models, we formally test for speed-mediated social interactions and verify that they are present. We further characterise this inferred social behaviour and find that despite the substantial shoal-level differences in movement dynamics between species, it is qualitatively similar in guppies and sticklebacks. It is intermittent, occurring in varying numbers of individuals at different time points. The speeds of interacting fish follow a bimodal distribution, indicating that they are either stationary or move at a preferred mean speed, and social fish with more social neighbours move at higher speeds, on average. Our findings and methodology present steps towards characterising social behaviour in animal groups.  相似文献   

10.
胶东—京畿地块在古生代并非“铁板一块”。中泥盆一早石炭世,裂解再生临津江—烟南冒地槽带;中、晚石炭世,郯庐海湾仲入成“诸城海湾”,并可能有二叠纪沼泽盆地。中生代运动使胶东地块复杂化。  相似文献   

11.
内分泌干扰物17β-雌二醇荧光分子印迹识别方法   总被引:4,自引:0,他引:4  
17β-雌二醇是近年来人们最为关注的重要内源性内分泌干扰物,它对生态系统和人体健康会产生一定的危害.采用分子印迹技术,通过丹磺酰氯与17β-雌二醇反应,合成出17β-雌二醇荧光标记物;建立了微球法合成17β-雌二醇荧光标记化合物分子印迹微球聚合物的方法,所获得的微球粒径均匀,平均为300~400 nm;分子印迹微球聚合物在不同极性溶剂中对17β-雌二醇荧光标记化合物的结合常数顺序为乙腈>甲醇>水>二氯甲烷,其结合量的差异并不显著,平均值为9.74μmol/g.该分子印迹微球聚合物可用于对复杂介质中17β-雌二醇的快速、简便检测.   相似文献   

12.
王宁  彭胜  陈家军 《环境科学》2014,35(7):2785-2790
蒸汽-空气混合注射法是一种新近发展起来的并具有较好应用前景的包气带非水相液体(NAPLs)污染修复方法.为探讨蒸汽-空气混合注射法的修复过程及机制,本研究采用石英砂模拟包气带松散介质,选取三氯乙烯作为典型污染物,在二维土箱内人工设置不同的污染方式和污染区域,开展混合注射修复实验.结果表明,混合注射有效地改善了SVE法后期出现的"拖尾"现象,其修复过程可分为SVE阶段、蒸汽加强阶段和热量穿透阶段;污染区域零散分布与单一分布相比,热量穿透土箱的时间变短,TCE去除率更高,去除速率更快.污染区域零散分布与单一分布条件下,热量穿透时间分别为60 min、69 min,去除率分别为93.5%、88.2%,去除时间分别为83.9 min、90.6 min,缩短了修复时间;另外,在污染区域单一分布的实验中发生TCE污染羽的积累与下渗现象,降低了TCE去除效率,在污染区域零散分布实验中温度过渡带更宽,温度峰前冷凝的NAPL态TCE减少.  相似文献   

13.
为了克服利用微型动物群落物种变化指示活性污泥运行状态存在的微型动物鉴别误判、分类和统计分析工作量大等问题,通过PCA法的相关性分析判断絮体微观形态参数降维成综合指标的可能性,采用“微型动物运动视频采集+定量图像分析”法表征微型动物的运动速度(平均线速度V和平均角速度W),分析SBR系统中锐利楯纤虫(A.lynceus)等7种自由运动型微型动物的运动速度与污泥絮体微观特性之间的相关性.结果表明:多个污泥絮体微观形态参数之间存在较好的相关性,可降维成2大综合指标(絮体大小密实度(SC)和絮体形状规则度(SR)).絮体SC和SR指标与须足轮虫属(Euchlanis sp.)、凹扁前口虫(F.depressa)和锐利楯纤虫(A.lynceus)的运动速度之间具有较显著相关性(|r|>0.50,P<0.05),因此利用典型的自由运动型微型动物运动速度变化能够快速指示污泥絮体的微观形态变化.  相似文献   

14.
We propose the basic structure of a neuronal circuitry possibly underlying the detection of discontinuities in the optical flow by the visual system of the housefly. The main features of the circuitry are: binocular cells summate elementary movement detectors over a large visual field and inhibit each one of them; inhibition is of the shunting type, with an inhibitory equilibrium potential very near the resting potential. A specific model implementing our proposal accounts for all the behavioral data on relative movement discrimination, including the characteristic dynamics of the response.  相似文献   

15.
Microbial spheres: a novel cyanobacterial–diatom symbiosis   总被引:2,自引:0,他引:2  
Cyanobacteria, algae and bacteria are widespread inhabitants of North Sea microbial mats. Our studies of these populations showed uncommon modes of living and extraordinary structures, which have not been described before. The structures are spherical objects covering a community of cyanobacteria, diatoms and bacteria. The cultivation of these communities in the laboratory and intensive observations of their exceptional movement has led to some spectacular findings. The sphere formations go through different phases with variation in the dominance of different microorganisms. The role of the bacteria is the most important in the first phase, and can be increased by the addition of signal substances. Spheres surrounded by envelopes of unknown composition and permeability appear, with numerous bacteria and sporadic diatoms inside. Then the cyanobacteria penetrate the spheres and arrange themselves at the surface. The communities proliferate over some weeks and are finally released. Laboratory expositions of the microbial communities to different parameters pinpoint the limits of sphere formation. The metabolic products of the sphere communities are concentrated in the spheres and lead to a different kind of compound compared with the surrounding environment. In this way, the microbial communities strongly influence the structure of the sediments. Uncommon circular structures, which develop into spheres between 0.08 and 3 mm in size were found in subcultures of non-axenic filamentous cyanobacteria enrichments from North Sea microbial mats. These filamentous cyanobacteria (Phormidium sp.) together with associated benthic diatoms of the genus Navicula and associated heterotrophic bacteria were held as reproducible synergistic cultures. Phormidium sp. filaments tightly intertwined with each other, formed the surface of the spheres, trapping diatoms inside. The formation of "spheres" was the result of radial and synchronous movements of the cyanobacteria. In old cultures, the direction of the cyanobacterial movement has turned in the opposite direction, away from the sphere. The integrity of large "spheres" was influenced by chemotactic phenomena and maintained by some type of trichome-trichome interaction. This suggests the presence of metabolic secondary products, which attract cyanobacteria and influence their movement in a form of chemotactic response.  相似文献   

16.
童昕  王涛  黄慧婷  王兆龙 《中国环境科学》2018,38(10):3868-3873
基于2014年和2015年环保部发布的省级回收数据,分析了现有传统回收体系下,各省的电子废物回收率变化,发现省级尺度电子废物的回收率呈现较大波动,这与电子废物的跨省流动有密切关系.为此,本文基于现有回收渠道的省际流动网络格局,采用网络分析中的层次聚类方法,揭示全国电子废物流动的区域化特征.结果显示根据区域化特征重新划分市场区,可以使主要市场区的整体回收率波动明显降低,从而为制定合理的回收目标提供参考.针对这一研究结果,提出基于市场区域化特征,建立全国一体化的回收利用市场和差异化的区域性回收目标,有助于充分利用市场机制优化中国电子废物循环利用的空间格局.最后,讨论了生产者主导和处理企业主导两种治理机制对空间优化的潜在影响.  相似文献   

17.
There is potential for synergy between the global environmental conventions on climate change, biodiversity and desertification: changes in land management and land use undertaken to reduce net greenhouse gas emissions can simultaneously deliver positive outcomes for conservation of biodiversity, and mitigation of desertification and land degradation. However, while there can be complementarities between the three environmental goals, there are often tradeoffs. Thus, the challenge lies in developing land use policies that promote optimal environmental outcomes, and in implementing these locally to promote sustainable development. The paper considers synergies and tradeoffs in implementing land use measures to address the objectives of the three global environmental conventions, both from an environmental and economic perspective. The intention is to provide environmental scientists and policy makers with a broad overview of these considerations, and the benefits of addressing the conventions simultaneously.  相似文献   

18.
随着快速城市化以及农村劳动力转移,长三角区域欠发达地区乡村耕地资源利用呈现新特征,从主体角度开展该区域耕地资源利用研究对乡村治理以及农业高质量发展具有重要影响。以江苏盐城和南通为例,通过问卷调查以及结构方程模型,分析农户耕地资源利用行为意向及影响因素。结果表明:苏北沿海地区不同耕地规模农户的耕地利用行为意向存在显著性差异。农户耕地资源利用行为意愿主要直接受到农户户主个人及家庭特征和耕地资源禀赋特征两个因素影响,政策认知以及技术与资金使用对其产生间接影响且程度较弱。苏北沿海地区乡村治理过程中亟需进一步开展农户分类管理与引导,促进耕地适度规模化经营,加强农户技能与政策培训,探索农业服务新模式,促进耕地资源精准管理、农业高质量发展以及乡村振兴等目标实现。  相似文献   

19.
乡村可持续发展与建设是乡村振兴的目标与愿景,也是推进城乡发展一体化、构建可持续城乡融合系统的落脚点,在城市化进程不断加剧背景下,明确乡村发展阶段与状态、测度发展潜力对有效识别乡村未来发展方向和模式、实现乡村可持续发展与建设具有重要意义。以地处淮海经济区核心区的苏北地区为研究对象,以7980个行政村为评价单元研究村域单元的乡村发展状态,通过县域尺度上对城乡发展阶段进行约束,以“差异化+一致性”的思路进行乡村发展潜力的综合测度。研究结果如下:(1)研究区乡村可分为“城镇主导”“城乡联动”和“乡村主导”三类发展阶段,数量占比分别为15.38%、46.15%和38.46%;(2)研究区乡村发展状态指数最大值和平均值分别为6.209和1.714,具有高值区、低值区集聚的特征;(3)研究区乡村发展潜力最大值和平均值分别为2.827和0.923,发展潜力为低、较低、中等、较高和高的评价单元占比分别为4.45%、15.20%、23.22%、35.39%和21.74%;(4)依据乡村发展潜力可将研究区分为“重点挖潜区”“权衡挖潜区”“适度挖潜区”及“重要维护区”四类,建议分别采用“激发隐性活力,缩小区内差距”“以优势要素带动,实现区域权衡发展”“明确发展劣势条件,适度填补潜力空间”及“保持发展模式,实现稳定发展”的发展思路。  相似文献   

20.
淮北平原“四水”转化模型实验研究与应用   总被引:1,自引:0,他引:1  
论文基于野外实验,采用五道沟实验站和杨楼实验区1965-2007年长系列资料,考虑土壤水垂向运动和再分布、冠层截留、蒸发、填洼、大孔隙、潜水排出补给地表水等要素,采用野外实验数据逐步细化和确定参数,提出淮北平原集总式“四水”转化模型,并提出一种新的冠层截留量年内分布确定方法。模型物理意义明确,对资料的要求较低,实用性较强。模型在杨楼流域应用结果表明,模拟流量过程线精度较高,在潜水位变动过线的拟合上效果较优,在径流过程和土壤含水量的拟合上表现较好。通过模型逐年计算统计,得出杨楼实验流域1991-2007年逐年及多年平均“四水”转化定量关系,为该区水文预报和作物水利用提供技术依据。  相似文献   

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