The spatial-temporal pattern and influencing factors of negative air ions in urban forests, Shanghai, China

Negative air ions are natural components of the air we breathe Forests are the main continuous natural source of negative air ions （NAI）. The spatio-temporal patterns of negative air ions were explored in Shanghai, based on monthly monitoring in 15 parks from March 2009 to February 2010. In each park, sampling sites were selected in forests and open spaces. The annual variation in negative air ion concentrations （NAIC） showed peak values from June to October and minimum values from December to January. NAIC were highest in summer and autumn, intermediate in spring, and lowest in winter. During spring and summer, NAIC in open spaces were significantly higher in rural areas than those in suburban areas. However, there were no significant differences in NAIC at forest sites among seasons. For open spaces, total suspended particles （TSP） were the dominant determining factor of NAIC in sum- mer, and air temperature and air humidity were the dominant determining factors of NAIC in spring, which were tightly correlated with Shanghai＇s ongoing urbanization and its impacts on the environment. R is suggested that urbanization could induce variation in NAIC along the urban-rural gradient, but that may not change the temporal variation pattern. Fur- thermore, the effects of urbanization on NAIC were limited in non-vegetated or less-vegetated sites, such as open spaces, but not in well-vegetated areas, such as urban forests. Therefore, we suggest that urban greening, especially urban forest, has significant resistance to theeffect of urbanization on NAIC.

Factors influencing the concentration of negative air ions during the year in forests and urban green spaces of the Dapeng Peninsula in Shenzhen, China

Negative air ions(NAIs)benefit the mental and physical health of humans,but rapid urbanization can decrease the abundance of NAIs.Quantifying the spatial and seasonal distribution of NAIs and determining the factors that infl uence the concentration during urbanization is thus essential.In the present study of a typical developing urban district in southern China,negative air ion concentrations(NAICs)in 60 forests sites and 30 urban green spaces were quantifi ed on seven consecutive days in each of the four seasons.Large seasonal variations in NAIC were revealed in forests and urban green spaces with trough values in summer.NAIC progressively decreased from forests to urban green spaces and was infl uenced by local land morphology,vegetation characteristics,and climatic factors.The vast,heavily vegetated northeastern region was the richest area for NAIs,whereas the narrow central region(urbanized area)was the poorest,implying dramatic impacts of urbanization on the spatial distribution of NAIs.The relationship between air temperature and NAIC was better fi tted with a quadratic equation than a linear equation.Moreover,the NAIC was more sensitive to local morphology in urban green spaces than in urban forests,indicating the vulnerability of NAIs in urbanized areas.Therefore,the appropriate design of local urban morphology is critical.

Research on Spatial Changes of Negative Air Ion Concentration in Hefei City

[Objective] The study aimed to discuss the spatial changes of negative air ion concentration in Hefei City. [Method] Based on the observation of air ions, temperature, relative humidity, the spatial changes of negative air ion concentration in different districts of Hefei City were ana- lyzed firstly, then the correlation between negative air ion concentration and meteorological factors was discussed. [ Result] Air cleanliness index （CI） of the parks, residential areas, industrial regions, transport stations and prosperous commercial districts was 0.86, 0.53, 0.37, 0.26 and 0.17 respectively, and the latter two regions suffered mild and moderate pollution separately. Daily variations of negative air ion concentration in the residential areas and parks of Hefei City were obvious, showing U shape, that is, the maximum values appeared in the morning and evening, while the minimum values could be found around 14 ：（30. There was no distinctly regular variation of negative air ion concentration in the prosperous com- mercial districts, transport stations and industrial areas. In Hefei City, the concentration of negative air ions showed an increasing trend from the ur- ban districts to the suburban districts; it was obviously higher in the residential areas and parks with numerous plants and waters compared with the prosperous commercial districts and transport stations. Negative air ion concentration correlated with relative humidity positively and temperature negatively, so the main meteorological factors influencing the negative air ion concentration in Hefei City were temperature and relative humidity. [ Coedusloa] The research could provide scientific references for city planning and greenbelt construction in future.

Oxidative Degradation of 2,4,6-Trichlorophenolin the Presence of Air Ions

2,4,6-trichlorophenol (TCP) was firstly treated with air ions generated by electric discharge, and high dechlorination (53%) was observed after 60 min treatment, indicating that air ions are an efficient dechlorination means and might have a future in the oxidative removal of chlorinated phenols. In addition, a stepwise degradation of TCP, beginning with the formation of a major product 2,6-dichloro-1,4-benzenediol via substitution, is proposed through a detailed analysis of gas chromatography/mass spectrometry.

Effect of a commercial air ionizer on dust mites Dermatophagoides pteronyssinus and Dermatophagoides farinae(Acari:Pyroglyphidae) in the laboratory

Objective:To investigate the short and long tenn efficacy of a commercial air ionizer in killing Dermatophagoides pteronyssinus(D.pteronyssinus)and Dermalophagoides farinae(D.farinae)mites.Methods:The effect of a commercial ionizer on D.pteronyssinus and D.farinae was evaluated in the laboratory,using a specially designed test.Mortality was assessed after 6,16and 24 hours for direct exposure and after 24,36,48,60 and 72 hours for exposure in simulated mattress.New batches of mites were used for each exposure time.Results:LT_(50)for direct exposure of ionizer was 10 hours for D.pteronyssinus and 18 hours for D.farinae.The LT_(50)for exposure in simulated mattress was 132 hours or 5.5 days for D.pteronyssinus and 72 hours or 3days for D.farinae.LT_(95)for direct exposure of ionizer was 36 hours for D.pteronyssinus and D.farinae.Meanwhile,the LT_(95)for exposure in simulated mattress was 956 hours or 39.8 days for D.pteronyssinus and 403 hours or 16.8 days for D.farinae.Conclusions:This study demonstrates the increasing mite mortalities with increasing exposure time of a commercial ionizer and suggests that negative ions produced by an ionizer kill dust mites and can be used to reduce natural mile populations on exposed surfaces such as floors,clothes,curtains,etc.However,there is reduced efficacy on mites inside stuffed materials as in mattresses and furniture.

Generation and Determination of Negative Air Ions

This review intends to cover a range of brief description of the generation mechanisms,the determination of the concentration,and the identification of negative air ions(NAI).This is divided into two parts:(i)it pays attention to the generation of NAI,which contains natural and artificial methods.According to the variation of energy in the environment,different methods based on natural generation are introduced in detail.As for artificial generation of NAI,corona discharge is dominantly elaborated due to its preponderance in convenient to control of the concentration of ions.(ii)it tends to introduce the determination of NAI,containing quantitative and qualitative detection,by using ion counting device and mass spectrometer,respectively.

Spatial Distribution Characteristics of Negative Air Ion Concentrations in Danqinghe Experimental Forest,Harbin City

In recent years, air ions, especially of negative air ion has received a universal attention for its health function. The density of negative air ion has become one of the important indexes that measure the air quality grade. With the air ions counter made in Japan, the spatial distribution characteristics of negative air concentrations at specific time in Danqinghe Experimental Forest were measured and studied, Harbin City, and the air quality was assessed by using ion polarity ration (q) and air ion assessment index (CI). The results showed that at a given time, the average concentrations of negative air ions were different for different forest types, stand origins, tree species and different parts of Balan River. There was a clear difference in ion polarity ration and air ion assessment index, and the air quality in different environments were also quite different.

Distribution Characteristics of Air Anions in Beidaihe in Different Ecological Environments

Qinhuangdao is a provincial municipality under the jurisdiction of Hebei Province and a coastal city in China. Beidaihe is a district under the jurisdiction of Qinhuangdao and is a famous seaside scenic area. Alliance Peak, located in Beidaihe seashore scenic West. Jinshan mouth is the peak of the Union Peak, located in the easternmost Beidaihe waterfront. In this paper, we use the observed data of air negative ions in the Beidaihe, Qinhuangdao, Jinshanzui and Lianfeng Mountains for seven years to study the distribution characteristics of negative air ions in different ecological environments through meteorological observation. Research shows that the annual mean of air anion concentration fluctuates less. The annual mean is 1730 ind·cm-3, and the difference between the highest and lowest concentrations is 535 ind·cm-3. The average air anion concentration was the highest in August at 7785 ind·cm-3 and the lowest in January at 365 ind·cm-3. Negative air ions have obvious spatial characteristics, and negative ion concentrations of the sea and forest air are significantly high. The average annual mean of the sea is 3902 ind·cm-3, and that of the forest is 5403 ind·cm-3. The concentration of air anion changes daily, and daytime concentration is significantly lower than nighttime concentration. The highest peak appears at night or in the morning, while the lowest value appears between noon and afternoon. Inter-annual features and concentration of negative air ions, as well as annual rain days, total rainfall, thunderstorm days, and average relative humidity, are negatively related to the annual average temperature and sunshine hours. However, in the average concentration of negative air ions, the average correlation test of meteorological elements was insignificant. The air anion concentration is negatively correlated with the PM2.5 concentration of fine particulate matter. The concentrations of nitrogen dioxide, sulfur dioxide, and carbon monoxide in the fine particulate matter are negatively correlated with the ozone concentration, which is positively correlated with ozone concentration and is tested by significance. Atmospheric discharge (thunderstorm) can produce a considerable amount of air anion. Air negative ions are an important indicator of air quality, which is of great significance to the living environment. The distribution of negative ions in the study space and its influencing factors in order to provide a basis for air quality assessment in the region and provide references for the long-term research on air anion in different urban areas.

Design and parametric optimization of thermal management of lithium-ion battery module with reciprocating air-flow

Single cell temperature difference of lithium-ion battery(LIB) module will significantly affect the safety and cycle life of the battery. The reciprocating air-flow module created by a periodic reversal of the air flow was investigated in an effort to mitigate the inherent temperature gradient problem of the conventional battery system with a unidirectional coolant flow with computational fluid dynamics(CFD). Orthogonal experiment and optimization design method based on computational fluid dynamics virtual experiments were developed. A set of optimized design factors for the cooling of reciprocating air flow of LIB thermal management was determined. The simulation experiments show that the reciprocating flow can achieve good heat dissipation, reduce the temperature difference, improve the temperature homogeneity and effectively lower the maximal temperature of the modular battery. The reciprocating flow improves the safety, long-term performance and life span of LIB.

Analysis of trace elements in air particulate matters by non-suppressed ion chromatography

The application of non-suppressed ion chromatography for monitoring of trace elements in air particulate matter was studied in the present investigation. The results indicate that the use of microwave acid digestion method is superior in comparison with the conventional thermal acid digestion method as it leads to higher recovery, better reproducibility, lower volatility loss, better protection against environmental contamination and much less digestion time (5 minutes vs. 24 hours). The use of eluent as extractant is shown to reduce the water dip problem in the chro-matogram. The addition of chelating agent in the eluent coupled with UV detection is shown to provide satisfactory chromatographic separation and good sensitivity for the analysis of transition metals present in the air particulate matter. Using the U.S. National Bureau of Standards Reference Material 1648 Urban Particulate Matter as standard for checking, the analytical procedure is shown to give good recovery and reproducibility for the detection of the following cations and anions in air particulate matter: Fe2 Cu, Mn, Pb, Zn, Mg, Na, HN4+, Cl-, NO3- and SO42-. Field test was also performed to check the applicability of the method and the results obtained were discussed in the present paper.

新余市森林游憩区空气负离子与PM_(2.5)动态变化规律及影响因子特征研究

为揭示江西省新余市森林游憩区空气负离子与PM_(2.5)时空分布特征、交互效应及其影响因素,对其森林环境中空气负离子和PM_(2.5)浓度时空分布特征及其与气象因子关系进行测定分析。结果显示:(1)新余市森林游憩区与城市绿地空气负离子年变化趋势总体保持一致,全年中各月份森林空气负离子浓度均显著高于城市绿地;1月、3月和4月城市绿地PM_(2.5)浓度显著高于森林,其他月份差异不明显;夏季6—8月空气负离子和PM_(2.5)浓度分别达到其全年最高值和最低值。(2)森林环境空气负离子浓度随海拔升高呈逐渐上升的趋势,PM_(2.5)含量呈先上升再下降的趋势;随距地面垂直高度的增加,林分中空气负离子浓度先下降再上升后保持不变,PM_(2.5)含量逐渐降低,距地面高10 m处林冠中层具有较高的空气负离子和较低的PM_(2.5)含量。(3)不同季节森林空气负离子与PM_(2.5)浓度均呈显著负相关,与空气气压、温度、相对湿度、风速和风向相关性各不相同。结果表明:新余市森林游憩区夏季、1000 m海拔山地、林冠层中部空气质量最优,是建设森林空气保健、疗养活动的理想场所。

干旱半干旱地区城市公园绿地空气负离子浓度特征及影响因素

为研究干旱半干旱地区城市公园绿地空气负离子浓度(NAIC)特征及影响因素,以呼和浩特市敕勒川公园为对象,于2020—2021年,每个季节选取晴天、晴间多云为主的天气各10 d,同步监测07:00—19:00时段,5种不同结构绿地(乔草型、乔灌型、乔木型、灌草型、乔灌草型)及对照区(CK)空气负离子浓度及PM10、PM2.5、温度、湿度、风速、大气压强、噪声等环境指标。结果表明:不同结构绿地空气负离子浓度季节日变化有所差异;同一季节,复杂结构绿地空气负离子浓度均值较高,不同结构绿地之间空气负离子浓度均值差异不显著;同一结构绿地,夏、秋季空气负离子浓度均值显著高于春、冬季;不同结构绿地空气清洁度夏、秋季较高,空气清洁度评价指数均值分别为0.58~0.78、0.52~0.80。绿地结构、季节对空气负离子浓度影响为主效应,绿地结构×季节对空气负离子浓度交互作用不显著;除此之外,相对湿度、PM10、PM2.5是影响空气负离子浓度的主要因素。

基于结构方程模型的森林生态系统空气负离子影响机制分析

空气负离子(Negative air ion, NAI)是衡量空气质量的重要指标之一,受到植被和环境的共同影响。然而,森林生态系统作为NAI产生的重要来源,森林中的植被和环境之间的相互作用以及对NAI的影响机制和贡献潜力仍难以捉摸。以暖温带森林生态系统中广泛分布的栓皮栎(Quercus variabilis BI.)为对象,基于自动观测设备长期定位观测获取了气象、土壤性质、空气洁净度以及植被光合等数据,利用皮尔逊相关系数分析和偏最小二乘结构方程模型分析了森林植被和环境要素对NAI的影响机制和贡献潜力。结果表明,环境要素和植被光合对NAI的贡献差异显著,植被光合对NAI的贡献潜力为62.65%,环境要素对NAI的贡献率为37.35%。环境要素中太阳辐射和饱和水汽压差的影响程度最大,分别为68.94%和16.55%。植被光合和PM2.5主要通过直接效应影响NAI,而光合有效辐射、紫外辐射、土壤温湿度和饱和水汽压差主要通过间接效应影响NAI。因此,利用结构方程模型可以阐明植被光合与环境要素的变化对NAI的影响趋势,从而全面揭示了森林生态系统中植被产生NAI的作用机制以及环境对NAI的影响趋势,并为评估森林生态系统对NAI的贡献潜力提供理论基础。

扬州城市森林负氧离子分布变化特征及其与气象因素的关系

【目的】分析扬州城市森林空气负氧离子浓度时空变化特征及其与气象因素的关系,为了解扬州城市森林空气负氧离子资源情况提供理论依据。【方法】依托江苏扬州城市森林生态系统国家定位观测研究站,以宋夹城体育休闲公园(城市森林)、茱萸湾风景区(城市近郊森林)和润扬湿地森林公园(城市远郊森林)为研究对象,收集3个区域的2020年1—12月空气负氧离子浓度和林内气象数据,比较不同季节之间负氧离子浓度的差异,分析负氧离子浓度与气象因素的相关性,并利用增强回归树分析各气象因素对负氧离子浓度的贡献率,结构方程模型分析各气象因素对负氧离子的直接和间接影响。【结果】扬州地区城市近郊森林区的空气负氧离子浓度日变化呈单峰型;城市近郊森林区与城市远郊森林区月变化趋势较一致,峰值分别出现在4月和6月。城市近郊森林区不同季节平均负氧离子浓度表现为春季>冬季>夏季>秋季,城市远郊森林区平均负氧离子浓度表现为夏季>冬季>春季>秋季。城市远郊森林区林内负氧离子浓度年平均值(666.87个/cm3)和郁闭度(0.80)低于城市森林区和城市近郊森林区,且森林郁闭度越高其负氧离子浓度的变异系数越小。城市森林区空气负氧离子浓度与风速、气压、空气温度和PM2.5存在显著(P<0.05,下同)或极显著(P<0.01,下同)相关性,城市近郊森林区和城市远郊森林区的空气负氧离子浓度与气压、风速、空气温度、空气湿度、PM2.5、光照强度等林内气象因素存在显著或极显著相关性。选择城市远郊森林区进行气象因素对空气负氧离子浓度的贡献率以及结构方程模型分析,结果表明空气湿度在春季(38.51%)和秋季(47.58%)对空气负氧离子浓度的贡献最大,而PM2.5在夏季(27.87%)和冬季(38.51%)对空气负氧离子的贡献最大;空气湿度对负氧离子浓度有直接正向影响,而光照强度对负氧离子浓度有直接负向影响,风向通过改变PM2.5对负氧离子浓度产生间接影响。【结论】扬州不同区域森林的负氧离子浓度变化规律不尽相同,不同季节和时间对空气负氧离子浓度有明显影响。根据不同区域的负氧离子浓度差异及其表现出的季节变化规律可制定不同的公园游览计划,建议夏季前往城市远郊森林区,春季前往城市近郊森林区游览。

制备条件对乙烯焦油调制包覆沥青性质的影响

以乙烯焦油为原料,采用空气氧化法制得锂离子电池石墨类负极材料用包覆沥青。考察了氧化温度、空气流量和氧化时间对包覆沥青物化性质的影响,并采用元素分析、热重分析、傅里叶变换红外光谱和核磁共振等方法对包覆沥青的物化性质进行了表征。结果表明,提高氧化温度、增大空气流量和延长氧化时间均能提高所制包覆沥青的结焦值和软化点。在氧化温度、空气流量和氧化时间分别为310℃、120 L/h和10 h的最佳制备条件下,可制得具有较高碳含量(w=93.44%)、较高芳香度和较少侧链(以短链为主)的高品质包覆沥青,其软化点、结焦值、喹啉不溶物质量分数和收率分别为258.90℃、70.19%、0.97%和39.99%。改性后石墨负极材料在150次循环后的容量保持率为89.74%。

离子色谱法测定工作场所空气中的草铵膦

用玻璃纤维滤纸采集工作场所空气中的草铵膦,经Metrosep A Supp 5-150型阴离子色谱柱分离,以1.92 mmol/L碳酸钠-0.60 mmol/L碳酸氢钠混合溶液为流动相,用离子色谱法测定。该方法在0 mg/L~1.04 mg/L范围内线性良好,方法检出限为0.012 mg/L,按采集30 L空气计算,最低检出值为0.004 mg/m3。空白玻璃纤维滤纸的加标回收率为93.7%~102%,标准溶液6次测定结果的RSD为0.8%~4.3%。

2020年天津市不同功能区空气负氧离子浓度时空分布及其与气象条件的关系

选用天津市2020年逐小时空气负氧离子和气象观测资料,对森林、湿地、城区3种典型功能区不同季节、不同天气的空气负氧离子浓度变化规律及其与气象要素的关系进行分析。结果表明:空气负氧离子浓度为森林>湿地>城区,夏季>春季>秋季>冬季,雨天最高,雪天最低,森林晴天负氧离子浓度略高于雾天,湿地和城区晴天略低于雾天。空气负氧离子浓度日变化呈双峰型,日变化幅度森林>湿地>城区,夏季>春季>秋季>冬季。空气负氧离子浓度总体与气温、相对湿度、水汽压、过去24 h降水量呈正相关,与气压呈负相关,与能见度相关关系不一致,与风速相关关系不显著。不同季节、不同天气条件的空气负氧离子浓度与气象要素的相关关系存在差异。城区空气负氧离子浓度受人类活动干扰较大,变化规律较森林和湿地更加复杂,与气象要素的相关关系总体较差。

负氧离子技术在汽车布置上的应用研究

近些年,空气质量状况得到了人们的广泛关注和重视。有调研结果显示,汽车车内空间是一个空气质量状况相当恶劣的场所之一,而人们使用汽车已经变得越来越普遍,这就对汽车内的空气质量提出了更多更高的要求。首先,文章介绍了负氧离子技术的作用和原理,特别是对负氧离子技术在汽车内的布置应用进行了研究分析;其次,主要是在车内不同位置布置不同数量的负氧离子发生器,并测试空调出风口和驾乘人员头部区域的负氧离子数量,以此获得负氧离子净化效果与布置位置及数量的关系;最后,测试在选用不同的空调风量和模式的情况下,空调出风口和驾乘人员头部区域的负氧离子数量,可以获得负氧离子浓度与空调风量及模式的关系。研究结果表明,负氧离子发生器布置在空调吹面出风口时,可以带来较好的车内空气质量净化效果,而使用较大风量吹面则会带来较高浓度的负氧离子。该研究结果为负氧离子技术在汽车内的布置应用提供了依据,具有一定的实用价值。

不同植物群落的空气负离子浓度分布特征及其差异分析

植物群落对空气负离子浓度具有直接影响。于2022年4—12月在太原理工大学植物园开展实地观测,选取8种不同类型的植物群落为研究对象,测定空气负离子浓度、空气温度、相对湿度、PM_(2.5)、PM_(10)等指标,分析不同植物群落空气负离子浓度变化差异及其影响因素。结果表明:①不同季节空气负离子浓度的日变化趋势不一致,春季呈上升趋势,其中09:00—10:00和17:00—18:00时段升幅较大,中午时段较为平稳;夏季呈上午上升、中午下降、下午再次上升的变化趋势,并且各植物群落在17:00—18:00时段达到全天最高值;秋季呈现先升高后降低的变化趋势,即早晚时段空气负离子浓度较低,上午10:00—12:00达到全天最高值;冬季变化不明显;②不同植物群落夏季空气负离子浓度值高于春秋两季,且植被组成结构复杂的植物群落高于植被组成结构简单的群落,其中,S4(侧柏Platycladus orientalis+核桃Juglans regia+紫叶李Prunus Cerasifera)和S7(山楂Crataegus pinnatifida)两个植物群落的空气负离子浓度均值高于其他群落;③不同植物群落空气负离子浓度与气象因素的相关关系不一致,总体呈现出与空气温度正相关,与相对湿度、PM_(2.5)和PM_(10)负相关的规律。