动态法测试空气净化器甲醛去除性能的研究

通过动态法测试水吸收型空气净化器A和活性炭过滤吸附型净化器B对甲醛的去除性能,探索更为合理的方法以评价空气净化器对气态污染物的去除性能.对净化器A去除甲醛的短期测试结果表明,净化器对甲醛浓度为0.3、0.5、0.8和1 mg/m3的连续空气流均有明显的净化效果,对甲醛的去除速率在0.91～2.78 mg/h之间.对净化...     

甲醛对洋葱根尖细胞的遗传毒性效应

将不同浓度(0.1%、1.0%、1.5%和3%)的甲醛溶液作为诱变剂,分别处理洋葱根尖24、36和48 h.通过常规染色体压片技术,观察洋葱根尖细胞有丝分裂现象.研究甲醛对洋葱根尖细胞有丝分裂指数(MI)和染色体畸变的影响,探讨甲醛的遗传毒性和洋葱作为甲醛污染指示植物的可行性.结果表明:不同浓度的甲醛溶液均能使洋葱根尖...     

鼎湖山大气气态总汞含量和变化特征的初步研究

利用高时间分辨率自动大气测汞仪(Tekran,2537B),于2009.10—2010.4对珠三角背景点鼎湖山大气气态总汞(TGM)进行了连续7个月的野外观测.结果表明,鼎湖山地区TGM的年均含量为(5.54±2.89)ng·m-3,含量明显高于全球大气汞含量的背景值(1.5～2.0ng·m-3)和国内部分地区的背景值,表明该地区大气受到了一定程度的汞污染.监测期间,4月TGM含量最高,11月最低.日变化特征显示白天TGM浓度比晚上高,属典型白天控制型.鼎湖山地区TGM主要受珠三角的区域污染影响,TGM含量变化与大气中NO2、SO2的相关性分析和与用电需求变化对比表明,珠三角人为源(尤其是燃煤的汞排放)对鼎湖山大气TGM有较大的贡献.     

广州市大气气态总汞含量季节和日变化特征

利用高时间分辨率自动测汞仪(tekran 2537B),于2010-11~2011-11对广州市大气气态总汞(TGM)进行了连续1a的观测.结果表明,广州市大气气态总汞的年平均含量为(4.86±1.36)ng/m3,表明该地区受到了一定程度的大气汞污染.TGM浓度按季节表现为:春季>冬季>秋季>夏季.TGM污染呈现春高夏低的现象,气象因素如边界层、静止风是影响其季节分布不同的主要原因.日变化趋势为中午最低,早晚出现2个高峰,边界层和温度对TGM日变化有很大影响.对广州市大气气态汞的可能来源分析结果表明,TGM主要来源于本地人为排放,其中市内燃煤电厂和水泥厂等人为源排放可能是广州市大气气态总汞的主要来源.     

大气硝酸测量方法研究进展

大气中硝酸(HNO3)的生成是排放到空气中氮氧化物(NOx)的主要沉降途径,对降水酸化、二次细颗粒物中硝酸盐的形成以及在研究光化学污染和霾形成等大气复合污染过程之间的联系中具有重要作用.获得高时间分辨率、准确的大气HNO3测量数据对研究和认识大气中NOx的循环机理是十分必要和迫切的.大气中的HNO3浓度低且具有很强的吸...     

基于氨基酸的甲醛吸收净化研究进展

甲醛是室内环境中典型的气态污染物之一,具有致畸性和致癌性.我国室内甲醛污染形势严峻,相关居民健康事件频发,去除室内甲醛对改善室内空气质量,降低人类健康风险十分必要.基于氨基酸吸收的甲醛净化技术以其绿色高效的除醛效率成为最有应用前景的甲醛净化技术,是当前研究的热点.本文总结了近年来基于氨基酸除醛的研究进展,包括:(1)简...     

Formaldehyde Exposure in a Gross Anatomy Laboratory. Personal Exposure Level Is Higher Than Indoor Concentration (5 pp)

Goal, Scope and Background Cadavers for gross anatomy laboratories are usually prepared by using embalming fluid which contains formaldehyde (FA) as a principal component. During the process of dissection, FA vapors are emitted from the cadavers, resulting in the exposure of medical students and their instructors to elevated levels of FA in the laboratory. The American Conference of Governmental Industrial Hygienists (ACGIH) has set a ceiling limit for FA at 0.3 ppm. In Japan, the Ministry of Health, Labour and Welfare has set an air quality guideline defining two limit values for environmental exposure to FA: 0.08 ppm as an average for general workplaces and 0.25 ppm for specific workplaces such as an FA factory. Although there are many reports on indoor FA concentrations in gross anatomy laboratories, only a few reports have described personal FA exposure levels. The purpose of the present study was to clarify personal exposure levels as well as indoor FA concentrations in our laboratory in order to investigate the relationship between them. Methods The gross anatomy laboratory was evaluated in the 4th, 10th and 18th sessions of 20 laboratory sessions in total over a period of 10 weeks. Air samples were collected using a diffusive sampling device for organic carbonyl compounds. Area samples were taken in the center and four corners of the laboratory during the entire time of each session (4-6 hours). Personal samples were collected from instructors and students using a sampling device pinned on each person's lapel, and they were 1.1 to 6 hours in duration. Analysis was carried out using high performance liquid chromatography. Results and Discussion Room averages of FA concentrations were 0.45, 0.38 and 0.68 ppm for the 4th, 10th and 18th sessions, respectively, ranging from 0.23 to 1.03 ppm. These levels were comparable to or relatively lower than the levels reported previously, but were still higher than the guideline limit for specific workplaces in Japan and the ACGIH ceiling limit. The indoor FA concentrations varied depending on the contents of laboratory sessions and seemed to increase when body cavity or deep structures were being dissected. In all sessions but the 4th, FA levels at the center of the room were higher than those in the corners. This might be related to the arrangement of air supply diffusers and return grills. However, it cannot be ruled out that FA levels in the corners were lowered by leakage of FA through the doors and windows. Average personal exposure levels were 0.80, 0.45 and 0.51 ppm for instructors and 1.02, 1.08 and 0.89 ppm for students for the 4th, 10th and 18th session, respectively. The exposure levels of students were significantly higher than the mean indoor FA concentrations in the 4th and 10th sessions, and the same tendency was also observed in the 18th session. The personal exposure level of instructors was also significantly higher than the indoor FA level in the 4th session, while they were almost the same in the 10th and 18th sessions. Differences in behavior during the sessions might reflect the differential personal exposure levels between students and instructors. Conclusion The present study revealed that, if a person is close to the cadavers during the gross anatomy laboratory, his/her personal exposure level is possibly 2 to 3-fold higher than the mean indoor FA concentration. This should be considered in the risk assessment of FA in gross anatomy laboratories. Recommendation and Outlook If the risk of FA in gross anatomy laboratories is assessed based on the indoor FA levels, the possibility that personal exposure levels are 2 to 3-fold higher than the mean indoor FA level should be taken into account. Otherwise, the risk should be assessed based on the personal exposure levels. However, it is hard to measure everyone's exposure level. Therefore, further studies are necessary to develop a method of personal exposure assessment from the indoor FA concentration.     

δ15N-stable isotope analysis of NHx: An overview on analytical measurements,source sampling and its source apportionment

• Challenges in sampling of NH₃ sources for d¹⁵N analysis are highlighted. • Uncertainties in the isotope-based source apportionment of NH₃ and NH₄⁺ are outlined. • Characterizing dynamic isotopic fractionation may reduce uncertainties of NH_x science. Agricultural sources and non-agricultural emissions contribute to gaseous ammonia (NH₃) that plays a vital role in severe haze formation. Qualitative and quantitative contributions of these sources to ambient PM_2.5 (particulate matter with an aerodynamic equivalent diameter below 2.5 µm) concentrations remains uncertain. Stable nitrogen isotopic composition (δ¹⁵N) of NH₃ and NH₄⁺ (δ¹⁵N(NH₃) and δ¹⁵N(NH₄⁺), respectively) can yield valuable information about its sources and associated processes. This review provides an overview of the recent progress in analytical techniques for δ¹⁵N(NH₃) and δ¹⁵N(NH₄⁺) measurement, sampling of atmospheric NH₃ and NH₄⁺ in the ambient air and their sources signature (e.g., agricultural vs. fossil fuel), and isotope-based source apportionment of NH₃ in urban atmosphere. This study highlights that collecting sample that are fully representative of emission sources remains a challenge in fingerprinting δ¹⁵N(NH₃) values of NH₃ emission sources. Furthermore, isotopic fractionation during NH₃ gas-to-particle conversion under varying ambient field conditions (e.g., relative humidity, particle pH, temperature) remains unclear, which indicates more field and laboratory studies to validate theoretically predicted isotopic fractionation are required. Thus, this study concludes that lack of refined δ¹⁵N(NH₃) fingerprints and full understanding of isotopic fractionation during aerosol formation in a laboratory and field conditions is a limitation for isotope-based source apportionment of NH₃. More experimental work (in chamber studies) and theoretical estimations in combinations of field verification are necessary in characterizing isotopic fractionation under various environmental and atmospheric neutralization conditions, which would help to better interpret isotopic data and our understanding on NH_x (NH₃ + NH₄⁺) dynamics in the atmosphere.     

室内空气净化技术应用效果研究进展

综述了过滤技术、吸附技术、静电技术、催化技术、等离子体技术等室内空气净化技术净化颗粒及有害气体效果的研究进展,并统计分析了北京市主流市场上国内外知名空气净化器应用各类净化技术的净化效果.同时,说明了各类技术在实际应用时的不足.最后展望了各类净化技术应用于室内空气净化器的发展趋势.     

生物膜填料塔净化低浓度甲醛废气的动力学模型研究

通过实验及动力学理论分析,对生物膜填料塔系统净化低质量浓度甲醛废气的适用动力学模型进行了研究.生物膜生化反应动力学分析显示,甲醛废气的生物净化有与其他挥发性有机废气(VOCs)不同的生化反应动力学特征,其反应类型判别准数M值远小于1(M=0.004(《)1.0),即生物膜中甲醛的生化反应速率远远小于其在液膜中的扩散速率,为慢速生化降解反应.针对净化低质量浓度甲醛废气的生物膜填料塔实验系统的研究表明,应用"吸收-生物膜"理论模型得到的甲醛净化效率、甲醛生化去除量和出口气体甲醛质量浓度的计算值与实验值之间的相关系数R分别到达了0.87、0.96和0.89,具有很好的相关性;而"吸附-生物膜"理论模型对应的相关系数R分别仅为0.64、0.84和0.64.与"吸附-生物膜"理论模型相比,"吸收-生物膜"理论模型描述甲醛废气生物净化过程具有良好的适用性,研究结果对生物法废气净化技术的相关基础理论研究和工程应用研究具有重要的参考价值.