Influence of haze pollution on water-soluble chemical species in PM2.5 and size-resolved particles at an urban site during fall

To investigate the influence of haze on the chemical composition and formation processes of ambient aerosol particles,PM_(2.5) and size-segregated aerosol particles were collected daily during fall at an urban site of Gwangju,Korea.During the study period,the total concentration of secondary ionic species(SIS) contributed an average of 43.9% to the PM_(2.5) ,whereas the contribution of SIS to the PM_(2.5) during the haze period was 62.3%.The NO_3 and SO~(2-)_4 concentrations in PM_(2.5) during the haze period were highly elevated,being 13.4 and 5.0 times higher than those during non-haze period,respectively.The PM,NO~-_3,SO~(2-)_4,oxalate,water-soluble organic carbon(WSOC),and humic-like substances(HULIS) had tri-modal size distributions peaks at 0.32,1.0,and 5.2 μm during the non-haze and haze periods.However,during the non-haze period they exhibited dominant size distributions at the condensation mode peaking at 0.32 μm,while on October 21 when the heaviest haze event occurred,they had predominant droplet mode size distributions peaking at 1.00 μm.Moreover,strong correlations of WSOC and HULIS with SO~(2-)_4,oxalate,and K+at particle sizes of 1.8 μm indicate that secondary processes and emissions from biomass burning could be responsible for WSOC and HULIS formations.It was found that the factors affecting haze formation could be the local stable synoptic conditions,including the weak surface winds and high surface pressures,the long-range transportation of haze from eastern China and upwind regions of the Korean peninsula,as well as the locally emitted and produced aerosol particles.     

What happens when you trust your supervisor? Mediators of individual performance in trust relationships

To understand how trust in supervisor translates into individual job performance, we hypothesize that trust in supervisor facilitates positive psychological conditions of meaningfulness, safety, and availability, which in turn predict individual job performance. We assert that each of the three mediating paths in our model represents a distinct mechanism by which trust in supervisor contributes to individual job performance. We test our hypotheses with 206 supervisor–subordinate dyads and find that trust in supervisor contributes to job performance through psychological availability and psychological safety but not psychological meaningfulness. By examining three different psychological mechanisms within the same frame, we provide a test that compares and contrasts the uniqueness of the three pathways. Our findings suggest practical ways for managers to build trust with subordinates and guidance for the design of productive work conditions. Copyright © 2012 John Wiley & Sons, Ltd.     

Analysis of Conditions and Organization of Work of Notebook Computer Users

Abstract

Aim. The aim of this study was to evaluate working conditions with a notebook computer (notebook) as a potential cause of musculoskeletal disorders. Material and methods. The study had 2 stages. The first one was a questionnaire survey among 300 notebook users. The next stage was an expert analysis of 53 randomly selected workstations. The questionnaire survey included questions about the participants, their working conditions, work organization and also duration of work with a notebook. Results and conclusions. The results of the research showed that most examined operators used a notebook as a basic working tool. The most important irregularities included an unadjustable working surface, unadjustable height of the seat pan and backrest, unadjustable height and distance between the armrests and no additional ergonomic devices (external keyboard, docking station, notebook stand or footstool).     

高效絮凝菌的培养条件优化

从呼和浩特市污水处理厂筛选分离了1株高效絮凝剂产生菌YS2,通过培养条件优化试验确定了该菌株产絮凝剂的最佳培养条件:碳源为蔗糖、氮源为脲、N/C为2.5∶1、初始pH值为6.0、培养温度为30℃。絮凝试验表明:该菌株产生的生物絮凝剂对高岭土悬浊液有良好的絮凝效果,絮凝率达到95%。絮凝活性分布试验表明其絮凝活性全部存在于离心沉降物中,而上清液没有絮凝活性。16S rDNA测序鉴定其为克雷伯氏菌G。     

南京冬季典型霾天气过程多元对比分析

选取2017～2020南京地区冬季3个典型霾天气过程,综合分析了霾天气过程中污染物、气象要素以及边界层条件等影响机制与特征变化.结果表明,3次过程中,AQI指数峰值分别为304(严重污染)、227(重度污染)与176(中度污染),且与PM2.5、PM10浓度变化基本趋于一致,PM25与PM10比值基本都大于0.7;污染...     

“5·12”地震前后都江堰市地表覆盖状况变化分析

本文以应用遥感技术,对“5·12”地震都江堰区域地表覆盖状况进行分析评价。选取都江堰市基于2007年的LandsatTM影像和2010年HJ-1卫星CCD影像,通过面向对象和目视解译相结合的方法,提取了草地、河流、旱地、水田、建设用地等9类生态类型环境覆盖信息。结果表明：“5·12”汶川地震对地表生态环境的变化较大,北...     

Characterization of biological responses under different environmental conditions: A hierarchical modeling approach

A natural river system is organized as a nested hierarchy of interconnected habitats with specific environmental conditions to which the biological community has adapted. Due to this hierarchical structure, identifying the role of different stressors on the biological community is a formidable task. Efforts trying to link stressors to biological integrity have always been bound to the geographic scale of the selected study area, leading to scale-specific results. In this research, an attempt is made to lift this limitation and develop a hierarchical, scale-sensitive methodology that can identify the significant environmental stressors to the biological community at different scales. Sites with similar background environmental conditions are clustered using self-organizing maps (SOM). This is used to identify stressors which affect the biological community throughout the area of study - called environmental gradients or large-scale stressors. Subsequently, these clusters of similar observations (sampling sites) are progressively sub-divided using environmental variables with a significant but localized effect on the biological community - called small-scale stressors. A parent group of sites is split only when the resulting sub-groups have significantly different biological responses. At the end of this recursive sites decomposition procedure, the original set of observations is organized as a tree of environmentally homogeneous groups of observations characterized by unique biological responses to multiple stressors with different geographic extents. The developed hierarchical analysis methodology has been validated using a large-size dataset of environmental observations from the State of Ohio. Our results show that habitat degradation and increased nutrient loading are the large-scale stressors with a widespread impact in Ohio. Other stressors, such as heavy metals, pH or nitrate concentrations have significant albeit localized effects on biological integrity.     

乌鲁木齐市可吸入颗粒物污染水平及其与气象因素的相关性分析

为了解可吸入颗粒物污染水平与气象因素之间的关系,从2008年9月—2010年2月采集乌鲁木齐市可吸入颗粒物样品,并对其随时间的变化特征及其与气象因素之间的相关性进行了统计分析。结果表明,采样时间内可吸入颗粒物中PM2.5和PM2.5-10的质量浓度的范围分别为38.2~468.7μg/m3和20.8~243.1μg/m3,平均浓度分别为134.2μg/m3和69.2μg/m3。可吸入颗粒物同时受几种气象因素的影响,其浓度与温度、能见度、风速呈负相关,与湿度呈正相关。     

京津冀地区城市臭氧污染趋势及原因探讨

采用Kolmogorov-Zurbenko（KZ）滤波分析了2013~2018年京津冀地区13个城市的臭氧最大日8h滑动平均（O₃-8h）序列,评估污染趋势并探讨原因.KZ滤波分离出的O₃-8h短期、季节和长期等3个分量分别占原始序列总方差的32.7%、63.9%和3.4%,各分量之间相互独立;以滤除了中短期过程影响的长期分量进行比较,京津冀地区远高于柏林、巴黎和伦敦等欧洲城市,与美国洛杉矶20世纪90年代初和最近4年状况相当,普遍低于上海和南京等长三角主要城市.但是,2013~2018年京津冀地区各城市臭氧污染加剧显著,长期分量升高速率达2.31~7.12 μg·（m³·a）^-1,均值为4.97 μg·（m³·a）^-1,快于长三角地区.拟合结果提示,臭氧浓度升高受气象条件影响不大（贡献比均值约为9.6%）,主要由大气污染排放变化造成（90.4%）,将该排放变化拆分为PM_2.5下降和臭氧前体物排放变化两项,其贡献比均值分别是27.3%和63.1%,其中北京-廊坊-天津城市带PM_2.5下降对臭氧升高贡献较大,分别为50.8%、32.5%和36.7%,衡水则达到48.6%.PM_2.5浓度降低已成为北京、衡水等地臭氧升高的最关键因素,这意味着需进一步减少前体物排放,以抵消PM_2.5降低导致臭氧增加的反作用.需要指出,该结果尚待实验和模型模拟验证.     

2014~2017北京市气象条件和人为排放变化对空气质量改善的贡献评估

2014～2017年北京地区霾日数和污染日数逐年减少,PM_(2.5)、PM_(10)、SO_2和NO_2年平均质量浓度下降,污染程度缓解,采暖期中的11～12月尤为明显.针对空气质量的显著改善,从气象条件的改善和减排措施两方面进行探讨分析,并结合数值模式和大数据挖掘技术实现气象和排放对大气污染贡献率的定量化研究.结果表明,2017年与过去3 a相比,平均风速增加7. 9%,≥3. 4 m·s~(-1)的风速频次最高(10. 6%),≥70%湿度日占比最小(25. 1%);其中,采暖期与过去3 a同期相比,小风日数减少8. 6%、大气环境容量指数和通风指数平均增加约11%,边界层高度以3. 2%·a~(-1)的速率升高,尤其11～12月各要素改善更显著,且该时段内2014年各因子变化与2017年相似.非采暖期(4～10月)累积降水量558. 3 mm,仅次于2016年,有利于污染物的清除和湿沉降.利用WRF-CHEM对霾和污染频发的12月进行模拟发现,气象要素的改变导致2017年12月北京PM_(2.5)质量浓度较2014～2016年同期分别降低5%、38%和25%.因缺少政府实际施行的减排方案,无法利用WRF-CHEM量化气象和减排的具体贡献率,因此借助大数据挖掘算法,基于K近邻算法(KNN)和支持向量机(SVM)模型对气象和减排对空气质量改善的贡献进行评估,结果显示2017年减少的霾日和重污染日,65. 0%归因于减排的贡献,35. 0%归因为气象条件的改善.可见,气象与生态环境部门应继续加强数据开放共享,科学开展气象条件预报与减排评估.