城市河流与湖库中痕量有机污染物的研究

通过采用ＧＤＸ－５０２富集,ＧＣ－ＭＳ分析,对城市河流、湖库中的痕量有机污染物进行分析,共检出５８种有机污染物,其中含有多种美国ＥＰＡ公布的重点污染物,从而为痕量有机污染物的研究建立了灵敏度高,分辨率好的测试方法。     

Is being a leader a mixed blessing? A dual‐pathway model linking leadership role occupancy to well‐being

Recent leadership research has drawn greater attention to how the well‐being of leaders influences leadership behaviors, follower performance and well‐being, and overall leadership effectiveness. Yet little attention has been paid to the relationship between occupying leadership positions and job incumbents' well‐being. This research addresses this question by developing and testing a dual‐pathway model. Our model proposes that incumbency in leadership positions is positively related to high levels of both job demands and job control, whereas job demands and job control have offsetting effects on well‐being. Results based on a longitudinal sample revealed that employees who transitioned from nonleadership positions to leadership roles showed trajectories of increasing job demands and job control, whereas such trends were weaker among those who remained in nonleadership positions. Findings from three additional samples generally demonstrated that leadership role occupancy was indirectly related to various indices of psychological and physiological well‐being through job demands and job control. Because the signs of the indirect effects through job demands and job control differed in expected ways, the overall relationship between leadership role occupancy and the well‐being outcomes was generally small and nonsignificant. We discuss research and practical implications of our framework and findings for organizations, employees, and leaders.     

From being diverse to becoming diverse: A dynamic team diversity theory

On the basis of the literature of open systems and team diversity, we present a new dynamic team diversity theory that explains the effect of change in team diversity on team functioning and performance in the context of dynamic team composition. Building upon the conceptualization of teams as open systems, we describe the enlargement and decline of team variety, separation, and disparity through member addition, subtraction, and substitution. Then, focusing on diversity enlargement, we theorize the contemporaneous and lasting effects of team diversity change on team performance change and on team processes and states leading to them. Dynamic team diversity theory expands the focus of team diversity research from teams' being more diverse than others to teams' becoming more diverse than before. It aims to advance team diversity research to be better aligned with the organizational reality of dynamic team composition. We also discuss methodological considerations in subsequent empirical testing of the theory and highlight how the theory and future research may help to guide organizational practice in recomposing work teams.     

Year-round film mulching system with monitored fertilization management improve grain yield and water and nitrogen use efficiencies of winter wheat in the dryland of the Loess Plateau,China

Environmental Science and Pollution Research - Year-round film mulching in winter wheat field facilitates rainwater storage in summer fallow period and reduces water evaporation in growing reason,...     

泥磷液相催化氧化氮氧化物

采用磷化工行业的固体废物泥磷液相催化氧化氮氧化物。实验结果表明,该方法是可行且有效的。随着温度的升高,泥磷吸收液的脱硝效率提高,当温度达到泥磷熔点时脱硝效率最佳。泥磷吸收液的脱硝效率随固液比的增大而有所下降,而随着NO体积分数和气体流量的增大,泥磷吸收液的脱硝效率呈先升后降的趋势。各因素对脱硝率的影响大小顺序为：气体流量>反应温度>固液比>NO体积分数。在反应温度60 ℃、固液比1∶4、NO体积分数0.03%、气体流量0.3 L/min的最佳工艺条件下,反应160 min的平均脱硝率可达97.38%。     

提高自动监控运维管理质量的若干思考

针对排污企业在线自动监控系统管理存在主体责任履行不到位,第三方运维企业人员流动性大且技术素质参差不齐等问题,对照污染源自动监控系统相关法律法规和标准,结合多年的污染源自动监控系统监督核查管理经验,提出排污企业应尽量安装同一品牌同一型号的自动监控设施、建立针对第三方的监督考核机制,运维企业应制定长期有效的管理机制、建立自动监控设施运行动态管理台账等建议,以提升企业自动监控系统管理水平,确保自动监控数据真实、合法、有效,为企业生态环境管理决策提供有力支持。     

Does underweight amplify the relationship between short-term particulate matter exposure and blood pressure in children and adolescents: a large cross-sectional study in a metropolis of China

Environmental Science and Pollution Research - Overweight/obesity modified the effects of ambient particulate matter (PM) exposure on blood pressure (BP). This study aims to assess whether...     

Persistent free radicals in humin under redox conditions and their impact in transforming polycyclic aromatic hydrocarbons

• Regulation of redox conditions promotes the generation of free radicals on HM. • HM-PFRs can be fractionated into active and inactive types depending on stability. • The newly produced PFRs readily release electrons to oxygen and generate ROS. • PFR-induced ROS mediate the transformation of organic contaminants adsorbed on HM. The role of humic substance-associated persistent free radicals (PFRs) in the fate of organic contaminants under various redox conditions remains unknown. This study examined the characterization of original metal-free peat humin (HM), and HM treated with varying concentrations of H₂O₂ and L-ascorbic acid (VC) (assigned as H₂O₂-HM and VC-HM). The concentration of PFRs in HM increased with the addition of VC/H₂O₂ at concentrations less than 0.08 M. The evolution of PFRs in HM under different environmental conditions (e.g., oxic/anoxic and humidity) was investigated. Two types of PFRs were detected in HM: a relatively stable radical existed in the original sample, and the other type, which was generated by redox treatments, was relatively unstable. The spin densities of VC/H₂O₂-HM readily returned to the original value under relatively high humidity and oxic conditions. During this process, the HM-associated “unstable” free radicals released an electron to O₂, inducing the formation of reactive oxygen species (ROS, i.e., ^•OH and ^•O₂⁻). The generated ROS promoted the degradation of polycyclic aromatic hydrocarbons based on the radical quenching measurements. The transformation rates followed the order naphthalene>phenanthrene>anthracene>benzo[a]pyrene. Our results provide valuable insight into the HM-induced transformation of organic contaminants under natural conditions.     

Health risk assessment of groundwater nitrate contamination: a case study of a typical karst hydrogeological unit in East China

Environmental Science and Pollution Research - Nitrate pollution in rivers, lakes, shallow groundwater, and even deep groundwater occurs in many parts of the world. And, it’s essential to...     

产业发展、土地集约利用与城市土地扩张

城市土地扩张速度过快是当前中国社会需要解决的一个重要问题。利用2000～2014年中国30个省会城市的面板数据,实证检验了全国层面和区域层面下,产业发展、土地集约利用与城市土地扩张之间的关系,并重点分析了土地集约利用在其中的中介作用。研究表明:(1)就全国层面看,第三产业规模提升和产业结构升级会抑制城市土地的扩张,土地集约利用在其中发挥部分中介效应,且其对总效应的贡献率分别为10.3%和12.6%;(2)就区域层面看,第三产业规模提升和产业结构升级会通过提高土地集约利用水平对东部城市土地扩张产生间接负向影响;第二产业规模增加对中部城市土地扩张有直接的促进效果;(3)该研究揭示了不同产业发展类型对不同区域城市土地扩张的影响及其中的作用路径,并针对性的提出了一系列政策建议,这对控制我国城市土地的过度扩张具有现实的指导意义。