Hydrous manganese dioxide adsorbing humic acid： controlling trihalomethane formation

Effectiveness of hydrous manganese dioxide (δMnO2) adsorbing humic acid under different conditions and its subsequent effects on trihalomethane (THMs) formation have been studied. Humicacid removal increases with higher pH and residual TOC decreases from 3.63 mg/L to 1.68 mg/L with pH increasing from 5.5 to 8.5 at 3.0 mg/L δMnO2; δMnO2 exhibits good potential of removing humic acid and the adsorbing potential as high as 1 mg TOC/mg δMnO2 is achieved; the fractional reduction of humic acid with higher molecular weight is about 30% higher than that with lower molecular weight. δMnO2 adsorption obviously reduces subsequent THMs formation; more significant THMs formation reduction is observed for humic acid with higher molecular weight. δMnO2 adsorption is an important factor that contributes to humic acid removal and THMs formation reduction in permanganate pre-oxidation process.     

磁改性海泡石对水源水中腐殖酸的吸附性能

为去除水源水中的腐殖酸(HA),自制磁改性海泡石(MSEP)并对其物化性能表征,研究MSEP对水源水中腐殖酸的吸附、脱附行为。结果表明,MSEP比表面积为25.354 m~2/g,比饱和磁化强度为32.36 A·m~2/kg。MSEP对HA的吸附等温线可用Langmuir方程拟合,吸附动力学符合准二级动力学方程。     

腐殖酸改性及其对镉的吸附特性

对腐殖酸改性前后表面理化性质的改变及其对水中镉离子的吸附性能进行了研究。结果表明,改性后腐殖酸比表面积和孔结构均有明显改善,吸附能力增强。吸附实验结果表明:随着pH的增大,改性后腐殖酸对镉离子的吸附量增加,在pH约为6时,吸附效率达到最大并趋于稳定; 改性后腐殖酸对镉离子的吸附最高可达20 mg/g,吸附等温线用Langmuir模型拟合最佳。吸附再生实验表明,改性腐殖酸吸附剂具有不易损失、易再生的特点,可以循环使用。     

复合胶体作用于Sr在花岗岩裂隙填充物中吸附行为研究

放射性废物地质处置过程中,核素在固液界面的吸附行为对核废物安全处置具有重要影响。本文以高放废物处置场花岗岩裂隙填充物为研究对象,通过批实验和微观表征技术研究了复合胶体作用下Sr在花岗岩裂隙填充物中的吸附规律。结果表明:腐殖酸胶体与针铁矿胶体结合成为有机–无机复合胶体的方式,主要依靠针铁矿胶体中所含羟基与腐殖酸胶体中所含羧基发生配位体交换反应,复合胶体以针铁矿胶体为主导,腐殖酸附着在针铁矿胶体表面;pH和固液比对复合胶体体系对Sr的吸附行为影响较大;通过改变溶液中Sr离子初始浓度进行等温吸附方程的拟合表明,该吸附体系的吸附为单层吸附且反应更快。结果可为放射性废物处理场中Sr的吸附行为提供科学规律认识。      

腐殖酸对污灌土壤中Cu、Cd、Pb、Zn形态影响的研究

选用白银地区污灌土壤为供试样品,在土样中分别加入腐殖酸、EDTA、柠檬酸三钠和乙酸,采用连续浸提法对比研究了外源腐殖酸对污灌土壤中有毒重金属不同形态的影响.实验结果表明,在污灌土壤中添加腐殖酸可改变土壤对重金属不同形态的吸持能力,使具有直接生物毒性的重金属可溶态急剧减少60%~80%,重金属氧化物结合态、碳酸盐结合态及有机结合态增加,从而降低重金属在土壤中的流动性、活性和生物可利用性.     

嗜酸乳杆菌表面疏水性对其亚油酸异构酶酶活的影响

研究碳源、氮源、生长时间以及生长温度对嗜酸乳杆菌细胞表面疏水性及其亚油酸异构酶酶活力的影响.通过Minitab15软件进行嗜酸乳杆菌亚油酸异构酶酶活力对其表面疏水性的回归分析,结果表明,嗜酸乳杆菌菌体表面疏水性与其亚油酸异构酶酶活成正相关关系,回归方程为:y=1.5500x+78.163.R2=0.7507说明模型有较高的拟合度,显著性分析P(0.003)P(0.05),结果显著,可作为响应预测.     

Detection of stratospheric ozone intrusions by windprofiler radars

Stratospheric ozone attenuates harmful ultraviolet radiation and protects the Earth's biosphere. Ozone is also of fundamental importance for the chemistry of the lowermost part of the atmosphere, the troposphere. At ground level, ozone is an important by-product of anthropogenic pollution, damaging forests and crops, and negatively affecting human health. Ozone is critical to the chemical and thermal balance of the troposphere because, via the formation of hydroxyl radicals, it controls the capacity of tropospheric air to oxidize and remove other pollutants. Moreover, ozone is an important greenhouse gas, particularly in the upper troposphere. Although photochemistry in the lower troposphere is the major source of tropospheric ozone, the stratosphere-troposphere transport of ozone is important to the overall climatology, budget and long-term trends of tropospheric ozone. Stratospheric intrusion events, however, are still poorly understood. Here we introduce the use of modern windprofiler radars to assist in such transport investigations. By hourly monitoring the radar-derived tropopause height in combination with a series of frequent ozonesonde balloon launches, we find numerous intrusions of ozone from the stratosphere into the troposphere in southeastern Canada. On some occasions, ozone is dispersed at altitudes of two to four kilometres, but on other occasions it reaches the ground, where it can dominate the ozone density variability. We observe rapid changes in radar tropopause height immediately preceding these intrusion events. Such changes therefore serve as a valuable diagnostic for the occurrence of ozone intrusion events. Our studies emphasize the impact that stratospheric ozone can have on tropospheric ozone, and show that windprofiler data can be used to infer the possibility of ozone intrusions, as well as better represent tropopause motions in association with stratosphere-troposphere transport.     

Global distribution of peroxyacetyl nitrate

Nitrogen oxides (NOx) have a central role in the chemistry of the atmosphere, especially in key processes relating to ozone, hydroxyl-radical (OH) and acid formation. High reactivity of NOx (lifetime of 0.5-2 days) precludes hemispheric-scale transport and it has been proposed that non-methane hydrocarbons present in the troposphere can transform NOx into its organic forms principally as peroxyacetyl nitrate (PAN). PAN is highly stable in the colder regions of the middle and upper troposphere and can provide a mechanism for NOx storage and transport. Once transported, PAN and its homologues can easily release free NOx in warmer atmospheric conditions. PAN is probably ubiquitous and its concentrations could exceed those of NOx in clean tropospheric conditions. Here we present the first view of the global distribution of PAN based on extensive shipboard and aircraft measurements. PAN is more abundant in the Northern than in the Southern Hemisphere and in the continental than in the marine troposphere. In contrast to its behaviour in polluted atmospheres, PAN mixing ratios in winter greatly exceed those in summer. These measurements provide a basis for assessing the significance of PAN as a reservoir of NOx and for extending and validating reactive nitrogen chemistry theory in the troposphere.     

霉菌生命活动对黄腐酸结构及生理活性的影响

为研究霉菌生长对腐植酸组分中黄腐酸分子的结构的影响，考察了经过霉菌生化作用的黄腐酸的化学组成和结构及其对植物生长的促进作用。结果表明，经过霉菌处理的黄腐酸的化学组成和结构都发生一系列变化：羧基含量减少，酚羟基含量增加，而烽醌基没有明显的变化，黄腐的Ｅ４／Ｅ６值下降。     

腐植酸类降滤失剂的研究进展

综述了腐植酸类物质修复污染土壤的机理及研究进展,分析了腐植酸类降滤失剂的降滤失机理,对腐植酸类降滤失剂进行了分类,剖析了腐植酸降滤失剂研制开发和应用中存在的问题,探讨了腐植酸类降滤失剂的主要发展趋势及应用方向.     

不同配比氮素形态对添加玉米秸秆白浆土有机碳官能团的影响

采用近边X射线吸收精细结构光谱及定量分析方法,对施入同等氮素用量、不同氮素形态组合n(NH+4)∶n(NO-3)=4,1,1∶4条件下添加玉米秸秆白浆土的有机碳(SOC)官能团进行系统分析.结果表明:添加任何形态的氮素均有助于微生物对混以秸秆白浆土SOC的矿化;氮素以铵硝等比例添加在促进SOC矿化分解方面更具优势,有利于白浆土富里酸组分的形成和积累,使其腐殖酸活性提升较大;硝态氮占优的氮素形态配比更有益于微生物在短期内对SOC的分解转化,微生物多以消耗C—OH获取能量,对于芳香碳也有一定累积作用,提高了SOC分子的整体复杂程度;铵态氮占优的氮素使微生物更易消耗SOC官能团中的羧基,促使其降解形成更多的醇羟基C—OH;混以玉米秸秆白浆土SOC官能团的主要类型有芳香烃C■C和C—H、脂肪烃、羧基C■O、醇羟基C—OH及石墨型C■C.     

枯草芽孢杆菌发酵生产腐植酸条件研究

以枯草芽孢杆菌为生产菌株,在蔗渣发酵培养基的基础上,采用一次回归正交试验,对腐植酸发酵过程中接种量、通气量(搅拌次数)、温度及时间4个因素对腐植酸产量的影响情况进行分析.试验结果表明,发酵时间的影响最为显著;所得到的回归方程有效且可信度高,回归方程为:y=4.6844+0.03251+0.0208A-0.041 9θ+0.202 5D,其中发酵时间、接种量和通气量与腐植酸产量呈正相关、与温度呈负相关.     

天然水体主要本底成分对催化臭氧氧化草酸的影响

采用浸渍法制备了Fe2O3负载活性炭（Fe2O3/AC）催化剂,考察了Fe2O3/AC催化臭氧氧化草酸的活性以及天然水体主要本底成分对Fe2O3/AC催化臭氧氧化草酸的影响. 结果表明,臭氧氧化草酸过程中Fe2O3/AC显示了良好的催化活性,草酸的去除主要基于催化贡献. HCO3-、CO32-及腐殖酸对Fe2O3/AC催化臭氧氧化草酸体系均有抑制作用. HCO3-和CO32-加入使催化臭氧氧化体系pH升高,进而降低Fe2O3/AC催化臭氧氧化草酸的活性. 此外,HCO3-和CO32-也是羟基自由基抑制剂,HCO3-、CO32-对体系的抑制作用从侧面验证Fe2O3/AC催化臭氧氧化草酸遵循羟基自由基机理. 腐殖酸加入体系后,与草酸形成竞争吸附和竞争氧化,从而抑制草酸的降解.     

Heterogeneous chemistry in the atmosphere of Mars

Hydrogen radicals are produced in the martian atmosphere by the photolysis of water vapour and subsequently initiate catalytic cycles that recycle carbon dioxide from its photolysis product carbon monoxide. These processes provide a qualitative explanation for the stability of the atmosphere of Mars, which contains 95 per cent carbon dioxide. Balancing carbon dioxide production and loss based on our current understanding of the gas-phase chemistry in the martian atmosphere has, however, proven to be difficult. Interactions between gaseous chemical species and ice cloud particles have been shown to be key factors in the loss of polar ozone observed in the Earth's stratosphere, and may significantly perturb the chemistry of the Earth's upper troposphere. Water-ice clouds are also commonly observed in the atmosphere of Mars and it has been suggested previously that heterogeneous chemistry could have an important impact on the composition of the martian atmosphere. Here we use a state-of-the-art general circulation model together with new observations of the martian ozone layer to show that model simulations that include chemical reactions occurring on ice clouds lead to much improved quantitative agreement with observed martian ozone levels in comparison with model simulations based on gas-phase chemistry alone. Ozone is readily destroyed by hydrogen radicals and is therefore a sensitive tracer of the chemistry that regulates the atmosphere of Mars. Our results suggest that heterogeneous chemistry on ice clouds plays an important role in controlling the stability and composition of the martian atmosphere.     

Polymer grafting modification of the surface of nano silicon dioxide

Based on the composite modification technology of the surface of nano silicon dioxide by non-soap emulsion polymerization, it is verified that there are polymer grafted on the surface of nano silicon dioxide. The modification mechanism and the bonding status on the surface of nano silicon dioxide after modification were suggested via the results of the infrared spectrum, transmission electronic microscope photograph and X-ray photoelectron spectrum. The hydroxyl formed by hydrolyzing of silane coupling agent reacts with hydroxyl on the surface of nano silicon dioxide to form Si-O-Si bonds by losing water molecules and hence the double bonds are introduced onto the surface of nano silicon dioxide. The surface of nano silicon dioxide is grafted with polymer through free radical polymerization between the double bonds on the surface of nano silicon dioxide and styrene under the action of initiating agent. The dispersibility of nano silicon dioxide and the controllability of surface modification of nano silicon dioxide can be greatly improved by the modification process.     

水稻田土壤及其提取物对腐殖酸和芘的吸附性能

分析了青紫泥和黄筋泥两种不同地区的水稻田土壤及其提取物对亲水性有机物腐殖酸和疏水性有机污染物芘的吸附性能,得出以下实验结果：水稻土壤类型对腐殖酸或芘的吸附持留能力无显著影响;土壤及其提取物对腐殖酸的吸附性能强弱依次为原土>黑碳>无机矿物;对芘的吸附性能原土和黑碳比较接近,Freundlich方程及其吸附解吸分配系数（Kf）能更好地反映出二者对芘的吸附性能;水稻土壤及其黑碳的亲水/疏水性能是二者对腐殖酸和芘吸附性能强弱的主要决定因素.     

Effect of calcium ion on the adsorption of dissolved humic acid onto TiO2 particles in water

In order to clarify the role of HA (humic acid)-TiO2 adsorption in the photocatalytic process, a series of experiments were performed to investigate the adsorption mechanisms in the absence or presence of calcium according to the intermolecular interaction force theory. Based on the experimental results, the models of adsorption mechanism were designed, which were useful in explaining the phenomena that happened during adsorption processes. The adsorption of humic acid onto the TiO2 particles was desperately pH-dependent; however, calcium could increase the amount of adsorption, which was mainly attributed to the calcium ion bridging. The effects of calcium concentration and TiO2 dosage on the adsorption process are also discussed.     

Reduction of soil carbon formation by tropospheric ozone under increased carbon dioxide levels

In the Northern Hemisphere, ozone levels in the troposphere have increased by 35 per cent over the past century, with detrimental impacts on forest and agricultural productivity, even when forest productivity has been stimulated by increased carbon dioxide levels. In addition to reducing productivity, increased tropospheric ozone levels could alter terrestrial carbon cycling by lowering the quantity and quality of carbon inputs to soils. However, the influence of elevated ozone levels on soil carbon formation and decomposition are unknown. Here we examine the effects of elevated ozone levels on the formation rates of total and decay-resistant acid-insoluble soil carbon under conditions of elevated carbon dioxide levels in experimental aspen (Populus tremuloides) stands and mixed aspen-birch (Betula papyrifera) stands. With ambient concentrations of ozone and carbon dioxide both raised by 50 per cent, we find that the formation rates of total and acid-insoluble soil carbon are reduced by 50 per cent relative to the amounts entering the soil when the forests were exposed to increased carbon dioxide alone. Our results suggest that, in a world with elevated atmospheric carbon dioxide concentrations, global-scale reductions in plant productivity due to elevated ozone levels will also lower soil carbon formation rates significantly.     

稀土元素与腐殖酸在水合氧化铁体系中的吸附机制

实验考察稀土元素(La3 、Ce3 、Ho3 、Yb3 )在水合氧化铁表面的吸附动力学过程,对比研究腐殖酸对吸附机制的影响.当腐殖酸与稀土元素共存时,腐殖酸通过化学吸附优先占据氧化铁表面的吸附点位,颗粒物表面特性因覆盖有机膜而得到修饰.初期的动力学过程主要表现为腐殖酸的竞争吸附,随后转变为吸附态腐殖酸对稀土元素的表面结合.轻稀土因较强的结合能力而比重稀土易于被吸附去除,这与天然水体中发生的稀土元素分异现象保持一致.     

AN FTIR SPECTROSCOPIC STUDY OF LOW TEMPERATURE PLASMA TREATED WOOL FABRIC

FTIR-ATR technique with second-order derivative measurement was used for assessing the amount of oxidation products of cystine present on the plasma-treated wool fabric surface. In this paper, three non-polymerising gases namely oxygen, nitrogen and 25% hydrogen/75% nitrogen gas mixture were used for the plasma treatment of wool fabric. The oxidation products of cystine studied included S-sulphonate, cysteic acid, cystine monoxide and cystine dioxide. The variations of the amount of these products as a function of treatment time were studied. Experimental results showed that the oxygen plasma could produce a large amount of oxidation products of cystine on the wool fabric surface followed by nitrogen plasma and gas mixture plasma.