Change of air quality and its impact on atmospheric visibility in central-western Pearl River Delta

Ambient air quality data, including atmospheric visibility, of Foshan city, a highly polluted city in the Pearl River Delta (PRD), and data obtained by the On-line Air Pollutant Exhaust Monitoring Network (OAPEMN), recently established by the National Emission Monitoring and Control Network for major industrial enterprises, were analyzed and are reported here for the first time, revealing the change in air pollution patterns and its impact on visibility degradation in the last decade. Reduced visibility of less than 8 km (after elimination of rainy and foggy periods) was found 22% of the time from 1998 to 2008, accompanied by elevated levels of pollutants, especially SO₂ and PM₁₀, in comparison with that of other developed cities. However, PM₁₀ showed a steady decreasing trend (0.004 mg m^???3 year^???1) during 2001?C2008, in contrast to the noticeable increase in ambient NO₂ concentrations from ~0.020 mg m^???3 before 2005 to above 0.050 mg m^???3 afterward. Multiple regression analysis revealed that the percentage of reduced visibility strongly correlated with PM₁₀ concentration, suggesting that visibility degradation was directly proportional to the loading of particles. Moreover, the fairly significant correlation between reduced visibility and NO₂ concentration also implied that the impact of primary emissions of NO₂ and enhanced secondary pollutants, formed via photochemical processes in the atmosphere, could not be ignored. The decreased PM₁₀ levels were obviously the predominant factor for the improvement in visibility (5.0% per 0.01 mg m^???3) and were likely due to the implementation of stricter air pollution control measures for industrial exhaust, which also resulted in reduced SO₂ pollution levels in the recent 2 years. In particular, the OAPEMN records showed an overall enhanced SO₂ removal by 64% in major industrial sectors. The continuous increase in road traffic and lack of efficient NO _x control strategies in the PRD region, however, caused an increase in ambient NO₂ concentrations.     

电子废弃物拆解厂排放多溴联苯醚和重金属的吸入性健康风险评估

以江苏某典型正规电子废弃物拆解厂为研究对象,在实测排放源数据的基础上,采用Calpuff大气扩散模式模拟其排放的多溴联苯醚(PBDEs)和重金属Pb、Cd大气浓度的区域与局部空间分布,进而对所排放PBDEs、Pb和Cd导致的健康风险进行评估.研究结果表明:在气象条件最为不利的情景下,污染物在东北、西南方向污染物扩散行为显著.PBDEs、Pb和Cd在区域空间范围的大气浓度最大值分别为3×10~(-6)、8.6×10~(-5)和3.6×10~(-6)μg·m~(-3),而局部范围的浓度则会高出一个数量级;其中BDE-209对于PBDEs的大气浓度贡献可达77%.在局部范围内,以HQ表达的PBDEs和Pb健康风险数值均在10~(-3)以下,非致癌健康风险极低;BDE-209和Cd的终生致癌风险最大值为1.10×10~(-12)与6.32×10~(-7),致癌风险可以忽略.该评估表明,正规操作的电子废弃物拆解厂的大气污染物不会对公共健康造成不可控风险.     

降低煤气吹脱解吸剩余氨水中碱耗量的研究

针对目前煤气吹脱解吸法处理焦化剩余氨水的过程中,碱的耗量较高的现状,结合具有专利技术的复合解吸塔,通过现场中试试验,研究了增加保温装置,改变加碱的位置,并适当增加了废水的停留时间的影响。最佳操作条件为:中位加碱,吹脱次数n=3,煤气温度T g=70℃,废水温度T w=90℃,pH=11,表面活性剂加入量ρ=10 mg/L,气液比q=350∶1,处理后的废水氨氮含量为248.2 mg/L,氨氮去除率可达到92.75%。最终的碱耗量为5.9 kg/m3,比原来的碱耗量降低了46.36%。     

Photocatalytic degradation of C. I. Reactive Red 24 solution with K6SiW11O39SnII

Environmental friendly materials, K₆SiW₁₁O₃₉Sn (SiWSn), was synthesized. SiWSn photocatalytic decomposition of C. I. Reactive Red 24 (RR24) with the UV-lamp (253.7 nm, 20 W), Xenon lamp filtered less than 390 nm light (500 W) and sun light was investigated. The results showed that RR24 solution could be effectively decolorized with the SiWSn photocatalyst. The photocatalytic degradation efficiency of RR24 with SiWSn was affected by the initial concentration of RR2 solution, the amount of SiWSn and the photolysis time. It is demonstrated that the process of photodegradation of RR24 with SiWSn is a pesudo first-order reaction, which can be described by Langmuir-Hinshelwood equation. Hydroxyl radicals and holes are both the main oxidants in the photocatalytic reaction of RR24 with SiWSn.     

改性GAC联合H2O2去除氨苄青霉素钠的研究

文章研究了用Fe（NO3）3NaOH改性的活性炭联合过氧化氢对水溶液中氨苄青霉素钠的处理效果．确定了它们的优化处理条件,并对两者的处理效果作了相应比较。在T=30℃,pH：3．0,青霉素初始浓度为200mg／L条件下,投加5．0g／LFe（N03）3改性活性炭和80mg/LH202,反应120min后,COD、TOC去除率分别可以达到88．5％和77．9％;在T=30℃,pH=70,青霉素200mg／L条件下,投加8．0g／LNaOH改性活性炭和80mg／LH202,反应120rain后,COD、TOC去除率分别可以达到85．2％和76．4％。     

电子鼻预处理装置的开发及适用性研究

针对气敏传感器的信号响应受气体湿度影响较大的问题,开发了一套用于快速检测和实时监测土壤中挥发性氯代烃污染的电子鼻的预处理装置.优选了干燥剂的材质,评价了最适干燥剂的除湿性能和对氯代烃化合物的吸附情况;把预处理装置与电子鼻联用,通过与气相色谱（GC）检测结果的比较,评价了其用于土壤通风净化过程监测的适用情况.结果表明：①以无水氯化钙和卤代烃分离管搭配组合的干燥装置效果最佳,湿度去除率达99%以上,电子鼻各传感器的基线值与对照组接近;②上述干燥剂连续通入湿度为75%的空气,90 min内湿度几乎可完全去除,120 min内湿度去除率保持在95%以上,对传感器的基线影响较小.③预处理装置未造成检测气体的吸附损耗,通入干燥预处理装置前后的挥发性氯代烃气体浓度差异只有3%～5%;④在土壤通风脱附过程的检测中,通气湿度98%以上的情况下,预处理装置在120 min内对湿度去除率达99%以上;电子鼻与GC对四氯乙烯污染物的检测结果线性拟合判定系数R2〉0.99（n=18）,表明配以干燥预处理装置的电子鼻能够较好地适用于土壤修复过程监测.     

发动机缸体开裂失效分析

目的研究发动机缸体出现开裂失效原因。方法通过化学成分分析、力学性能分析、断口扫描分析、显微组织分析、能谱分析及低倍缺陷分析测试手段,对发动机缸体的开裂模式及失效原因进行分析。结果发动机缸体原材料中Si元素超标,导致晶界析出较多的Al Si Cu及Al2Cu脆性相,在开裂区域组织存在过热过烧现象,两个原因导致组织晶间结合力大大降低。同时,在开裂区域存在热节效应,低倍疏松和缩孔较集中的现象,为热裂纹形成及继续扩展提供了有利条件。结论通过不断改进设计工艺,控制原材料成分及调节浇注参数,大大减小了热裂纹出现概率,在后序批量生产中,未发现类似失效样件。     

Assessing the life cycle study of alternative earth-retaining walls from an environmental and economic viewpoint

Environmental Science and Pollution Research - This research aims to assess the sustainability of the most common earth-retaining walls (Gravity Walls and Cantilever Walls) in terms of...