Application of ion chromatography to the determination of water-soluble inorganic and organic ions in atmospheric aerosols

A simple, sensitive and convenient ion chromatography(IC) method was established for the simultaneous determination of twelve water-soluble inorganic anions(F -, Cl -, NO - 2, NO - 3, SO 2- 3, SO 2- 4, PO 3- 4), and fifteen water-soluble organic ions(formate, acetate, MSA, oxalate, malonate, succinate, phthalates, etc.) in atmospheric aerosols. The linear concentrations ranged from 0.005 μg/m 3 to 500 μg/m 3(r = 0.999—0.9999). The relative standard deviation(RSD) were 0.43%—2.00% and the detection limits were from 2.7 ng/m 3 to 88 ng/m 3. The proposed method was successfully applied to the simultaneous determination of those inorganic ions and organic ions in PM 2.5 of Beijing.

On-line Measurement of Water-Soluble Ions in Ambient Particles

Combining the system of rapid collection of ambient particles and ion chromatography, the system of rapid collection of fine particles and ion chromatography （RCFP-IC） was established to automatically analyze on-line the concentrations of water-soluble ions in ambient particles. Here, the general scheme of RCFP-IC is described and its basic performance is tested. The detection limit of RCFP-IC for SO4^2-, NO3^-, NO2^-, Cl^- and F- is below 0.3μg m^-3. The collection efficiency of RCFP-IC increases rapidly with increasing sized particles. For particles larger than 300 nm, the collection efficiency approaches 100%. The precision of RCFP-IC is more than 90% over 28 repetitions. The response of RCFP-IC is very sensitive and no obvious cross-pollution is found during measurement. A comparison of RCFP-IC with an integrated filter measurement indicates that the measurement of RCFP-IC is comparable in both laboratory experiments and field observations. The results of the field experiment prove that RCFP-IC is an effective on-line monitoring system and is helpful in source apportionment and pollution episode monitoring.

Diurnal variations of water-soluble ions in PM_(2.5)in Shanghai

Thirty-six daily time interval PM2.5 samples were collected in different seasonal dates in urban Shanghai, and the concentrations of four anions （Cl- , NO3-, SO4^2-, C2O4^2-） and five cations （NH＋, Na＋, K＋, Ca2＋, Mg2＋） were analyzed with ion chromatography. Sulfate, nitrate and ammonium were found to be the dominant species, accounting for about 80% of the total ions. The daily nitrate to sulfate mass ratio ranged from 0.31 to 0.82, indicating that coal combustion was still the main pollution source in Shanghai. The equivalent ratio of ammonium to stun of nitrate and sulfate showed fixed diurnal variation pattern in all the sampling days with higher values in the nighttime, suggesting that fine particles in the night were more neutralized. The oxalate to sulfate ratio was lower in the winter sampling days than that in hotter summer and autumn sampling days. Oxalate was significantly correlated with sulfate in winter sampling days, but not in the summer and autumn, suggesting that the formation mechanism of oxalate and sulfate was similar in winter, however different in hot days.

Concentrations,sources,and influential factors of water-soluble ions of atmospheric particles in Dunhuang Mogao Grottoes,a world heritage site in China

Atmospheric particle pollution is one of the major factors leading to degradation of ancient wall paintings,particularly heritage sites in arid and semi-arid regions.However,current systematic research on the changes,sources,and influential factors of atmospheric particulate matter and its water-soluble ion concentrations is not sufficient.Thus,the major water-soluble ion concentrations,sources,and influential factors of atmospheric particles PM_(2.5) and PM_(10)(particulate matter with an aerodynamic equivalent diameter≤2.5 and 10.0μm,respectively,in ambient air)were collected from Cave 16 and its ambient exterior environment in the Dunhuang Mogao Grottoes,China,between April 2015 and March 2016.Results showed that the concentrations of PM_(2.5) and PM_(10) inside and outside the cave were the highest in March 2016 and the lowest in December 2015.The higher particle concentration from March to May was related to the frequent occurrence of sand and dust events,and the lower particle concentration from June to September was associated with good diffusion conditions,increased precipitation,and an established cave shelterbelt.The concentration of particulate matter inside the cave was affected by the concentration of particles in the air outside the cave.Ca2+,NH+4,Na+,Cl-,and SO2-4were the main components of the total ions of PM_(2.5) and PM_(10) both inside and outside the cave.The total ions inside the cave were frequently affected by the disturbance of tourists'activities during the peak tourist season from May to August.Under the influence of dust,the total concentrations of Cl-,SO2-4,Na+,NH+4,and Ca2+in particles of different sizes inside and outside the cave increased,and the concentrations of Cl-,SO2-4,Na+,and Ca2+decreased during precipitation period.Backward air mass trajectory analysis suggested that the pollutants were mainly from Xinjiang,China.The pollutant sources of air particulates are straw burning,secondary pollution sources,soil dust,dry spring rivers,and tourist activities.

Real-Time Observation on Water-Soluble Ions of PM_(2.5)in Beijing under the Influences of Different Air Masses in Summer

To further understand the variations of water-soluble ions in PM2.5 in Beijing,the authors observed their concentrations continuously and in high temporal resolution by the system for rapid collection of fine particles and ion chromatography(RCFP-IC) during 12–18 July 2010.These results combined with those of earlier backward trajectory research are used analyzed to determine the causes of concentration changes in water-soluble ions under the influences of two kinds of air masses in summer.The results indicate that concentrations of NO3-,SO42-,and NH4+ were influenced strongly by the continental air mass than by the marine air mass.Cl- and Na+ were not changed significantly.Because the sources of K+,Mg2+,and Ca2+ are mainly concentrated on land,their concentration levels were slightly higher under the control of continental air mass than that of the marine air mass.Variations of NO2- during the observation differed from those of other ions;its concentration was significantly higher under the influence of marine air mass.Moreover,the authors obtain the diurnal variations of eight water-soluble inorganic ions including NH4+,K+,Mg2+,Ca2+,Cl-,NO2-,NO3-,and SO42-.Diurnal variations of NH4+,NO3-,and Cl- showed single peak,which appeared before noon,while SO42- showed two peaks that appeared during rush hours.Those of Mg2+,Ca2+,and K+ showed single peak that appeared in the afternoon.That of NO2- showed with a peak appearing at sunrise and a valley appearing at sunset.

Influence of Basicity on the Formation of Cluster Ions/Adduct Ions for Organic Ammonium Halides by Positive Secondary Ion Mass Spectrometry

ＩｎｆｌｕｅｎｃｅｏｆＢａｓｉｃｉｔｙｏｎｔｈｅＦｏｒｍａｔｉｏｎｏｆＣｌｕｓｔｅｒＩｏｎｓ／ＡｄｄｕｃｔＩｏｎｓｆｏｒＯｒｇａｎｉｃＡｍｍｏｎｉｕｍＨａｌｉｄｅｓｂｙＰｏｓｉｔｉｖｅＳｅｃｏｎｄａｒｙＩｏｎＭａｓＳｐｅｃｔｒｏｍｅｔｒｙＦＵＨｕａ，...

Sheath structure in plasma with two species of positive ions and secondary electrons

The properties of a collisionless plasma sheath are investigated by using a fluid model in which two species of positive ions and secondary electrons are taken into account. It is shown that the positive ion speeds at the sheath edge increase with secondary electron emission（SEE） coefficient, and the sheath structure is affected by the interplay between the two species of positive ions and secondary electrons. The critical SEE coefficients and the sheath widths depend strongly on the positive ion charge number, mass and concentration in the cases with and without SEE. In addition, ion kinetic energy flux to the wall and the impact of positive ion species on secondary electron density at the sheath edge are also discussed.

Characteristics of Aerosol Pollution Under Different Visibility Conditions in Winter in a Coastal Mega-City in China

To investigate chemical profiles and formation mechanisms of aerosol particles in winter haze events,comprehensive measurements including hourly concentrations of PM2.5 and water-soluble inorganic ions and related gasphase precursors were conducted via an online monitoring system from January to March of 2016 in Shenzhen,a coastal mega-city in south China.In this study,high concentrations of PM2.5,NO2 and lower levels of O3 were observed during haze periods in comparison with clear days(Visibility>15 km).The major secondary ionic species were NH+4、NO-3 and SO2-4,which varied significantly on haze and clear days.The ratio of NO-3/SO2-4 in haze days was greater than that on clear days and tended to be larger when air pollution became more serious.At the same time,compared with previous studies,it has been found that the ratio has been increasing gradually in Shenzhen,indicating that the motor vehicle exhaust emissions have a more and more important impact on air quality in Shenzhen.Sulfur oxidation rate(SOR)and nitrogen oxidation rate(NOR)was higher during the haze period than that in clean days,indicating efficient gas to particle conversion.Further analysis shows that high concentrations of sulfate might be explained by aqueous oxidation,but gas-phase reactions might dominate nitrate formation.This study also highlights that wintertime nitrate formation can be an important contributor to aerosol particles,especially during haze periods.

Hydrochemical Characteristics and Ion Transfer of Rainfall of Betula Platyphylla Secondary Forest in Xiaowutai Mountain

In order to study hydrochemical characteristics and ion transfer of annual rainfall of Betula platyphylla secondary forest,water samples of rainfall,throughfall,stemflow,litter infiltration water and slope runoff of Betula platyphylla secondary forest in the early growth stage,fastgrowing stage and growth decline stage in Shanjiankou watershed of Xiaowutai Mountain and nine indexes of pH,Ca^2+,Mg^2+,K+,Na+,Zn^2+,Mn^2+,Fe^2+ and Cu^2+ were determined.The results showed that:①The annual rainfall was weakly alkaline,and the ion concentration in different stages was obviously different.According to the ratio of the maximum concentration to the minimum concentration of the same ion,the rank was Mg^2+ > Mn^2+ >Na+ > K+ > Ca^2+ > Cu^2+ > Fe^2+ > Zn^2+.②Compared with the rainfall in the same period,in the early growth stage,Mg^2+,Mn^2+,Na+,K+,Ca^2+,Fe^2+ and Zn^2+ showed leaching loss in each distribution process.In the fastgrowing stage,Ca^2+,Mn^2+ and Fe^2+ showed leaching loss in each distribution process;Mg^2+ showed absorption,Na+ showed leaching loss in slope runoff and showed absorption in other process.K+ showed leaching loss in stemflow and showed absorption in other process.Zn^2+ showed absorption in stemflow and slope runoff and showed a little leaching loss in other process.In the late growth stage,Ca^2+,Mg^2+,Zn^2+,Mn^2+ and Fe^2+ showed leaching loss in each distribution process;Na+ and Cu^2+ showed absorption;K+ showed absorption in stemflow and showed leaching loss in other process.Most of the rainfall and metal ions in Betula platyphylla secondary forest were intercepted by litter layer.

Feedback model of secondary electron emission in DC gas discharge plasmas

Feedback is said to exist in any amplifier when the fraction of output power in fed back as an input.Similarly,in gaseous discharge ions that incident on the cathode act as a natural feedback element to stabilize and self sustain the discharge.The present investigation is intended to emphasize the feedback nature of ions that emits secondary electrons（SEs）from the cathode surface in DC gas discharges.The average number of SEs emitted per incident ion and non ionic species（energetic neutrals,metastables and photons）which results from ion is defined as effective secondary electronemission coefficient（ESEEC,Eg）.In this study,we derive an analytic expression that corroborates the relation betweenEg and power influx by ion to the cathode based on the feedback theory of an amplifier.In addition,experimentally,we confirmed the typical positive feedback nature of SEEfrom the cathode in argon DC glow discharges.The experiment is done for three different cathode material of same dimension（tungsten（W）,copper（Cu）and brass）under identical discharge conditions（pressure：0.45 mbar,cathode bias：-600 V,discharge gab：15 cm and operating gas：argon）.Further,we found that theEg value of these cathode material controls the amount of feedback power given by ions.The difference in feedback leads different final output i.e the power carried by ion at cathode（Pi C￠∣）.The experimentally obtained value of Pi C￠∣is 4.28 W,6.87 W and9.26 W respectively for W,Cu and brass.In addition,the present investigation reveals that the amount of feedback power in a DC gas discharges not only affect the fraction of power fed back to the cathode but also the entire characteristics of the discharge.

A depressant for marmatite flotation:Synthesis,characterisation and floatation performance

This study synthesised a zincic salt(ZS)as a depressant for marmatite-galena separation.The effect of ZS on the flotation of marmatite and galena was investigated through micro-flotation tests.88.89%of the galena was recovered and 83.39%of the marmatite was depressed with ZS dosage of 750 mg·L^(−1)at pH=4.The depression mechanism of ZS on marmatite was investigated by a variety of techniques,including adsorption measurements,Fourier transform infrared(FTIR),X-ray photoelectron spectroscopic(XPS)analysis,and time of flight secondary ion mass spectrometry(ToF-SIMS).Results of adsorption tests and FTIR reveal that ZS adsorbed on marmatite surface and impeded the subsequent adsorption of butyl xanthate(BX).The results of XPS and ToF-SIMS indicate that the ZnO_(2)^(3-)released by ZS could be chemisorbed on the marmatite surface and depress marmatite flotation.

The Distortion of Energy Deposit Distribution of (12)～C Ions in Water

The transport process of 12C ions in water was studied with SRIM code and Geant4 toolkit. The SRIM results indicate that the transverse diffusion of 12C ion beam causes distortion of energy deposit along the beam direction. The distortion becomes more notable as the transverse diffusion increases. The simulation results of Geant4 indicate that the influence of secondary fragments on energy deposit distribution would be the main factor causing the distortion in higher energy range. In the region adjacent to the beam line where the contribution from 12C ions domi- nates, the contributions from secondary fragments are ignorable. The further from the beam axis the region locates, the larger the contributions from secondary fragments, until the contributions from secondary fragments are ignorable. The further from the beam axis the region locates, the larger the contributions from secondary fragments, until the contributions from secondary frag- ments exceed that of 12C. Among all the secondary fragments, the contributions of H, He and B ions are mostly notable. It is also found that some positron-emitting secondary fragments could be very useful for position emitting tomography （PET）.

The spatial and temporal distribution and characteristics of inorganic ion concentrations of TSP in the Tarim Basin

Based on Total Suspended Particulates （TSP） observations of Tazhong, Tikanli, Kashi and Minfeng in 2009, combined wa- ter-soluble inorganic ion analyses, this paper studied the spatial and temporal distribution of TSP in the Tarim Basin and analyzed concentration characteristics. The results are as follows： （1） monthly average TSP concentrations shows a similar trend in Tazhong, Tikanli, Kashi and Minfeng with peak values in April-May and low values in November-December. As for the quarter average mass concentration trends, spring has the highest value, followed by summer and autumn, and winter is the lowest; （2） total annual concentration trend of water-soluble inorganic ions in TSP is as follows： Tazhong 〉 Tikanli 〉 Minfeng 〉 Kashi. SO4^2- concentra- tions are 58%, 50%, 54% and 51% of total ion concentration; Ca^2＋ concentrations are 13%, 16%, 16% and 11%; Na^＋ concentra- tions are 12%, 13%, 10% and 12% and Cl^- concentrations are 12%, 16%, 11% and 22%, respectively. Therefore, sulfate, calcium, sodium and chloride ions are the main inorganic components of TSP in the Tarim Basin; （3） the correlation coefficients of anions and cations in Tikanli, Minfeng, Kashi and Tazhong are 0.99, 0.99, 0.25 and 0.91, respectively; the average anion concentrations are 2.57, 2.12, 2.15 and 3.02 times the average cation concentrations, indicating that ions were unbalanced; （4） SO4^2-/NO3^- ratio is much larger than the ratio of coal-fired emissions SO4^2-/NO3^-, thus the impact of fixed emission sources in the four regions on the atmosphere is far greater than that of mobile emission sources.

Ion Nonthermality Induced Nonlinear Dust Acoustic Wave Propagation in a Complex Plasma in Presence of Weak Secondary Electron Emission from Dust Grains

In this paper we have investigated the effect of ion nonthermality on nonlinear dust acoustic wave propagation in a complex plasma in presence of weak secondary electron emission from dust grains. Equilibrium dust charge in this case is negative. Dusty plasma under our consideration consists of inertialess nonthermal ions, Boltzman distributed primary and secondary electrons and negatively charged inertial dust grains. Both adiabatic and nonadiabatic dust charge variations have been taken into account. Our analysis shows that in case of adiabatic dust charge variation, at a fixed non-zero ion nonthermality increasing secondary electron emission decreases amplitude and increases width of the rarefied dust acoustic soliton whereas for a fixed secondary electron yield increasing ion nonthermality increases amplitude and decreases width of such rarefied dust acoustic soliton. Thus shape of the soliton may be retained if strength of both the secondary electron yield and the ion nonthermality are increased. Nonadiabatic dust charge variation shows that, at fixed non-zero ion nonthermality, increasing secondary electron emission suppresses oscillation of oscillatory dust acoustic shock at weak nonadiabaticity and pronounces monotonicity of monotonic dust acoustic shock at strong nonadiabaticity. On the other hand at a fixed value of the secondary electron yield, increasing ion nonthermality enhances oscillation of oscillatory dust acoustic shock at weak nonadiabaticity and reduces monotonicity of monotonic dust acoustic shock at strong nonadiabaticity. Thus nature of dust acoustic shock may also remain unchanged if both secondary electron yield and ion nonthermality are increased.

Impact of Winter Transit Air Masses on the Sources and Composition Characteristics of Atmospheric Pollution in Hengyang

Through the integration and analysis platform of particulate matter components,a preliminary comparison was conducted on the pollution contribution of the three winter transit air masses in December to environmental quality,and the changes and related relationships of water-soluble ions and particulate matter elements were analyzed.The results showed that winter transit air masses had a significant impact on the air quality in Hengyang.In the quantitative comparison of the primary pollutant contribution during the transit period of air masses,local sources and transit sources each accounted for half,and the impact of transit source on ambient air quality was much greater than that of seasonal base increase.Fine particulate matter was closely related to secondary ions,and particulate matter was closely related to primary ions.The transit of air masses promoted the improvement of secondary ion conversion rate,and the unit increment of fine particulate matter was greater than that of particulate matter.During the transit period,the mass concentrations of most water-soluble ions and most particulate matter elements maintained synchronous growth,with a superimposed effect.The composition ratio of organic carbon and nitrate ions increased,while the composition ratio of ammonia and sulfate ions decreased.Both disposable ions and secondary conversions in the composition of PM_(2.5)had increases and decreases.The high conversion rate of nitrate and the high composition ratio of ammonia radical in Hengyang indicated that transportation source factors had a significant impact on the local environmental quality of Hengyang.

京郊设施土壤盐分累积及组成变化特征

针对北京市郊区设施土壤存在次生盐渍化的问题,以房山、延庆、密云、大兴、昌平地区规模化设施园区为研究对象,采用田间随机取样的方法,对5个地区主要栽培类型的设施园区土壤盐分累积和组成变化进行研究,以期为设施栽培的科学管理和高效施肥提供参考。结果表明,79%的点位土壤全盐量≥2.0 g/kg,69.3%的点位电导率≥50 mS/m,次生盐渍化趋势明显;监测园区的盐分离子均有一定程度的富集,不同地区盐分离子累积存在一定差异;除HCO_(3)^(-)外,K^(+)、Na^(+)、Ca^(2+)、Mg^(2+)、Cl^(-)、SO_(4)^(2-)、NO_(3)^(-)的累积在一定程度上均造成了土壤的次生盐渍化,其中阳离子以Ca^(2+)、Mg^(2+)为主,阴离子以SO_(4)^(2-)、NO_(3)^(-)为主;京郊设施土壤盐分组成主要以硝酸盐和硫酸盐的形式存在。针对北京郊区存在盐分累积现象,建议开展有机肥料的筛选和品质质量检测,同时加强水肥管理,避免加重土壤次生盐渍化程度。设施生产中不仅要注重经济效益,更应该关注土壤的健康状况,以实现设施生产可持续的发展目标。

阴离子密堆二次电池正极材料中离子宿住迁移与能量存蓄机制晶体化学新探索

在二次电池电极材料中,有一类性能优良的材料具有阴离子密堆或近密堆方式构筑的晶体结构。宿住阳离子在密堆留下的空隙空间中宿住、迁移,从而实现能量转换与存储。相关过程微观机理的研究由于涉及原子尺度的微观结构辨析和电子层面的分析,实验研究难度较大。因此,更多是通过晶体学理论分析与晶体场理论和量子力学第一性原理计算结合展开。已有的理论从过渡金属配位体晶体场分析展开,但宿住离子宿住迁移中电子相互作用关注相对不足。本文根据已有的实验事实,在精准描述最具代表性的阴离子(氧离子)面心立方紧密堆积(FCC)结构中空隙空间准确形态和微分几何方法准确解析空腔真实体积的基础上,结合空隙空腔独特形态,对经典晶体学中Pauling第一规则的分析方法作了拓展。根据新的理解,提出了宿住阳离子在空隙空腔宿住和徒迁拓扑形变新模式,及其可能拥有的电子形态学新特征,提出了空隙空腔中宿住阳离子体积与密堆阴离子半径间的新关系。为了进一步说明住宿离子电子形态特征,通过第一性原理计算获得了典型FCC结构LiMn_(2)O_(4)尖晶石中电子密度等势图,构造了锂离子宿住四面体空隙空腔的电子密度等势特征分布的三维形态,与晶体学分析中获得的电子形态新特征变化一致。通过夹在两个密排面间的{110}面族电子云密度分布分析,首次清晰地揭示了LiMn_(2)O_(4)中锂离子的“S”形徒迁途径,及其对附近锰离子配位多面体电子云密度分布的影响。依据宿住离子脱/嵌新特征,提出阴离子拓扑多面体晶体场对宿住阳离子电子云压缩发生拓扑变形实现能量转换储蓄的新思路,据此计算了典型紧密堆积构造的电极材料新的理论能量密度,并和传统方法计算的理论值进行了比较,二者十分接近,为从晶体学和量子力学理解二次电池能量储存提供了新视角。

酸岩反应过程模拟实验及残酸离子变化规律——以大庆油田为例

酸岩反应复杂,反应过程中会产生大量离子,可能随着pH值升高生成二次沉淀,从而影响酸化效果,因此分析酸岩反应过程中离子变化规律是酸化配方的技术关键。选取盐酸、土酸与大庆油田储层岩屑模拟酸岩反应,通过反应后酸液pH值梯次调控,模拟油层条件下酸岩反应进程及离子浓度变化规律。结果表明,pH值调节过程稀释倍数对残酸中金属离子浓度变化影响小,可不做考虑,放置时间以6 h为最佳;Ca^(2+)、Fe^(3+)、Al^(3+)是盐酸残酸产生二次沉淀的主要离子,Ca^(2+)、Fe^(3+)、Al^(3+)、Si^(4+)是土酸残酸产生二次沉淀的主要离子。在对酸岩反应机理及二次沉淀产生原因分析的基础上,自主研发了能减少酸岩反应二次沉淀的酸液——高络合酸,通过将高络合酸与土酸残酸进行定量对比和评价,验证了高络合酸具有抑制二次沉淀生成的效果,为提高酸化效果提供了新的思路。

赤泥中稀土提取与分离技术研究进展

稀土元素被誉为“工业维生素”,具有优异的磁、光、电性能。随着新能源汽车等新兴行业对稀土需求量的不断增加,稀土资源日益紧缺,从二次资源中回收稀土已成大势所趋。作为一种重要的二次资源,赤泥的产量高、堆存量大、稀土含量较高。本文介绍了赤泥中稀土元素的赋存状态,概述了从赤泥中提取分离稀土元素的湿法浸出工艺和火法-湿法联合工艺;介绍了溶剂萃取法和离子交换法两种分离工艺的研究现状,对比分析了不同处理工艺的优缺点,并通过比较不同工艺的优劣,指出降低回收成本、提高环境效益是未来赤泥资源化利用研究的重要方向。

离子轰击二次发射电子枪束流引出问题的仿真与实验研究

为应对电子束荧光技术对电子枪的需求,本文开展了离子轰击二次发射电子枪的研究工作。首先介绍了离子轰击二次发射电子枪的工作原理,将工作过程划分为离子产生及引出、二次电子产生和引出两个部分并展开理论分析;基于辉光放电原理建立了简化的空气放电仿真模型,利用Comsol软件获得了正离子密度及其分布;对于加速室内的二次电子发射过程采用静电聚焦的方式聚焦电子束,利用Comsol软件基于Nelder-Mead算法获得二次电子引出的最佳结构参数;最后,搭建了电子枪原理样机,实验结果表明:采用空气作为工作气体,利用气体放电产生的正离子轰击金属铝使其发射二次电子,最终获得了加速电压为20 kV,束流强度为16 mA的电子束,完成了此类电子枪的原理验证并为性能提升工作奠定基础。