兰州地区大气污染的化学组成及来源解析

为探究大气污染的特征,于2020年5月—2021年4月在中国西北部的兰州市区采集了总悬浮颗粒物样品227个,利用离子色谱仪、热/光碳分析仪对主要水溶性离子、元素碳(EC)和有机碳(OC)的质量浓度进行了测定.结果显示,兰州地区大气总悬浮颗粒物质量浓度均值为(376.7±974.8)μg·m^-3,高于国家环境空气质量二级标准(NAAQS),呈昼低夜高的变化特征主要是由于兰州地区夜间大气多处于静稳状态导致的污染物累积效应.水溶性阴、阳离子按质量浓度排序为NO₃^->SO₄^2->Cl^-、Ca²⁺>NH₄⁺>Na⁺>K⁺>Mg²⁺,其中二次离子(NO₃^-、SO₄^2-、NH₄⁺     

过硫酸盐去除石灰土介质中汽油BTEX的效果及乙醇的影响

为了认识岩溶区石灰土含水介质中化学氧化联合生物降解去除燃油苯系物的效果,以汽油中的苯、甲苯、乙苯和二甲苯(BTEX)作为污染物,通过批实验研究过硫酸盐(PS)联合硝酸盐去除汽油BTEX的效果,并认识不同浓度乙醇(EtOH)存在时带来的影响及化学氧化与反硝化联合修复的可能性.结果表明,在35 d内各组的BTEX去除率均达到91.00%以上,PS化学氧化能有效地去除BTEX.在不含EtOH及含EtOH初始浓度为500和5000 mg·L^-1的情况下,BTEX浓度在第65 d时分别为未检出、0.226 mg·L^-1、0.243 mg·L^-1,去除率分别为99.98%、99.00%、98.70%,其中,苯的去除率分别为99.98%、97.01%、93.32%.随着EtOH浓度的增加,苯的去除受到抑制,EtOH对BTEX的化学氧化具有阻碍作用.石灰土介质中高铁含量对PS具有活化能力,高含量有机质能促进PS分解,并导致pH值回升,出现反硝化作用和硫酸盐还原作用,有利于生物降解作用的恢复.     

精细化工固定源废气采样时机的选择探讨

以某医药企业某产品生产过程为实例,综合各工段生产步骤、时间、废气产生情况及估算的污染物浓度等因素,绘制各污染因子排放规律图,从而确定各污染因子排放浓度(排放量)最大的1 h为最佳采样时机。     

核化危害源项反演技术现状及研究展望

源项反演对缓解和遏制核化危害源、精准预测核化危害时空传输和扩散情况、辅助作战行动和保障决策等具有十分重要的意义.本文从源项反演应用平台和源项反演关键算法(包括欧拉方法、拉格朗日方法、深度学习等)两个方面,对国内外核化危害源项反演技术的现状和二者间的差距进行了总结与分析.研究指出,利用深度学习提高反演精度和速率、从单污染...     

生态修复工程实施后对土壤理化性质改善效益初探

通过监测和田地区生态修复项目实施后所取得生态效益的结果表明,生态修复项目实施后,由于项目区风速降低,温度和相对湿度的变化减少,提高了植被盖度,降低了风蚀量,促进了成土作用的进行,从而逐渐改善了土壤的理化性质。     

高速公路交通噪声预测模型探讨

针对我国当前广泛使用的2种高速公路噪声预测模型《06规范》预测模型与《09导则》预测模型在预测时比较研究,重点利用环境现状监测数据分别对2种模型验证与对比分析.结果表明,2种模型预测值与实测值相差3dB ～5dB,车流量＞ 300辆/h,《09导则》更接近实测值;在夜间车流量＜300辆/h,《06规范》更接近实测值,2种模型结合采用《06规范》计算的车速,距离衰减考虑车流量的大小,在此基础上应用《09导则》,预测结果与实测值更为接近.     

化工装置停工放空过程中VOCs排放及估算方法

通过分析化工企业典型开、停车过程的排污节点,表明停车过程中大气挥发性有机污染物主要来自装置退料结束后挂壁、底部滞留和内部空间蒸气等滞留在设备内部的残余物料。在总结化工装置停工放空过程中大气挥发性有机物来源的基础上,讨论并提出大气污染排放量估算方法。     

黄河中上游能源化工区大气污染跨界环境影响分析

对黄河中上游能源化工区近地面和边界层顶气象流场及该区域大气污染长距离输送产生的跨界环境影响趋势特征进行了分析。结果表明,该区域近地面和边界层顶的流场总体上为西北向东南流动,大气污染物长距离输送可能影响的区域主要为华中地区;区域冷空气的活动对其大气污染物的清除起重要作用;通过CALPUFF模型的模拟结果表明,该区域SO2的影响程度和范围明显大于NO2,在区域内部存在污染物浓度较高的区域,但未对区外造成显著跨界环境影响。     

Structural equation model analysis for the evaluation of overall driving performance: A driving simulator study focusing on driver distraction

Objective: The present research relies on 2 main objectives. The first is to investigate whether latent model analysis through a structural equation model can be implemented on driving simulator data in order to define an unobserved driving performance variable. Subsequently, the second objective is to investigate and quantify the effect of several risk factors including distraction sources, driver characteristics, and road and traffic environment on the overall driving performance and not in independent driving performance measures.

Methods: For the scope of the present research, 95 participants from all age groups were asked to drive under different types of distraction (conversation with passenger, cell phone use) in urban and rural road environments with low and high traffic volume in a driving simulator experiment. Then, in the framework of the statistical analysis, a correlation table is presented investigating any of a broad class of statistical relationships between driving simulator measures and a structural equation model is developed in which overall driving performance is estimated as a latent variable based on several individual driving simulator measures.

Results: Results confirm the suitability of the structural equation model and indicate that the selection of the specific performance measures that define overall performance should be guided by a rule of representativeness between the selected variables. Moreover, results indicate that conversation with the passenger was not found to have a statistically significant effect, indicating that drivers do not change their performance while conversing with a passenger compared to undistracted driving. On the other hand, results support the hypothesis that cell phone use has a negative effect on driving performance. Furthermore, regarding driver characteristics, age, gender, and experience all have a significant effect on driving performance, indicating that driver-related characteristics play the most crucial role in overall driving performance.

Conclusions: The findings of this study allow a new approach to the investigation of driving behavior in driving simulator experiments and in general. By the successful implementation of the structural equation model, driving behavior can be assessed in terms of overall performance and not through individual performance measures, which allows an important scientific step forward from piecemeal analyses to a sound combined analysis of the interrelationship between several risk factors and overall driving performance.     

Virtues and humanitarian ethics

This paper analyses the contribution of virtue ethics, the study of good character traits, to the humanitarian context. It argues that a virtue ethics perspective paints a realistic picture of the use of ethical standards in morally complex circumstances. Virtuous relief workers can employ standards in their thinking, but they are also committed to professional excellence that goes beyond any formal code. The concept of virtue ethics places a stress on moral development, which can be facilitated by role models that impart modest and feasible ideals. However, virtue ethics cannot provide simple guidelines on how to resolve difficult situations. It is possible that two virtuous persons can disagree on what should be done in a particular instance. In addition, a virtue ethics perspective emphasises the need for both individuals and organisations to discuss the actual purpose of relief work in order to pinpoint the virtues of a good relief professional.