Formation and Transport of Atmospheric Aerosol over Athens, Greece

The effects of meteorology on ambient aerosol concentrations and aerosol transport, within the Greater Athens Area during the summer period, was investigated. Measurements of size fractionated anions and cations were made at two sites (inland at Ag. Stefanos and on the coast at Pireas) within the Greater Athens Area. The wind regime exhibited a distinctinfluence such that the sea-breeze circulation strongly enhanced the formation of secondary aerosols. For sulphate the difference in concentration between the two sites was,on average, 8 times greater on sea-breeze days compared with Etesian days (warm days with NE winds). During `normal' days,any differences in concentrations were possibly due to localemissions. Elevated concentrations in the fine mode were detectedat both sites during the sea-breeze days. The sea-breezecirculation enhances the development of secondary aerosolswhich was clearly shown at the inland site. Nitrous acid,hydrochloric acid and particulate nitrate, sulphate andammonium increase during sea-breeze days. Elevated levelsof nitrate, 4 m diameter, were particularly observedon the days with a strong sea-breeze circulation. Sulphatewas well correlated with both sulphur dioxide and ammoniumsuggesting the production of NH₄HSO₄/(NH₄)₂SO₄ aerosols, formedthrough the neutralisation of NH₃ with sulphuric acids.Ammonium sulphate was found to be the major ammoniumcomponent in Athens.     

充装条件对水基热气溶胶灭火剂燃速影响规律的研究

水基热气溶胶灭火剂是以替代哈龙为目的而研制的新一代灭火制；主要论述了充装量，充装密度，燃烧器结构等充装条件对水基热气溶胶灭火剂燃烧速度的影响规律，并分析了充装量，充装密度，燃烧器结构影响燃烧速度的原因。     

The Precautionary Principle: Scientific Uncertainty and Omitted Research in the Context of GMO Use and Release

Commercialization of genetically modified organisms (GMOs) have sparked profound controversies concerning adequate approaches to risk regulation. Scientific uncertainty and ambiguity, omitted research areas, and lack of basic knowledge crucial to risk assessmentshave become apparent. The objective of this article is to discuss the policy and practical implementation of the Precautionary Principle. A major conclusion is that the void in scientific understanding concerning risks posed by secondary effects and the complexity ofcause-effect relations warrant further research. Initiatives to approach the acceptance or rejection of a number of risk-associated hypotheses is badly needed. Further, since scientific advice plays a key role in GMOregulations, scientists have a responsibility to address and communicate uncertainty to policy makers and the public. Hence, the acceptance of uncertainty is not only a scientific issue, but is related to public policy and involves an ethical dimension.     

电热原子吸收法测定大气中微量元素镉

用HNO_3—HClO_4硝解聚氯乙烯膜,用石墨炉原子吸收法直接测定大气颗粒物中的镉,方法准确度使用标准物质,在选定的条件下,相对误差0.011％,变异系数为10.83％,回收率在90.2～101.6％,方法操作简便测定速度快。     

寒区湿地软土固结变形特性试验研究

软土的成因不同,其工程性质存在着一定的差异,路基的固结沉降也不一样。为了研究寒区湿地软土固结变形特性,弄清其固结和次固结系数变化规律,对两类软土进行了单向固结压缩试验。试验结果表明,软土在不同的固结压力作用下,其孔隙比-时间对数曲线展布特征有较大的不同,说明固结压力对寒区湿地软土的主、次固结的划分有影响;寒区湿地软土主固结系数随固结压力的增大而减小,次固结系数随固结压力的增大而增大,最后两者都趋于稳定。     

城市污水二级处理出水中沙门氏菌的PCR检测

建立了一种利用PCR检测城市污水二级处理出水中沙门氏菌的方法.采用膜吸附-洗脱法浓缩二级出水水样中的沙门氏菌,通过选用一对涵盖性和特异性均较强的引物139和141,对浓缩后的沙门氏菌进行PCR检测.利用正交试验法,对沙门氏菌PCR体系进行五因素四水平的试验,建立了沙门氏菌PCR的最佳体系.通过梯度PCR考察了退火温度对检测结果的影响,选择65℃作为退火温度,优化后沙门氏菌PCR体系的检测灵敏度可达0.314ngL.通过对已知细菌浓度的水样进行检测,确定了该法检测水样中沙门氏菌的灵敏度为2130CFUL.与传统MPN法的相比,该法在检测效果和检测效率上都优于MPN法.     

Eperimental study of photooxidation products of ethylbenzene

Smog chamber experiments were performed to investigate the composition of products formed from photooxidation of aromatic hydrocarbon ethylbenzene.Vacuum ultraviolet photoionization mass spectrometer and aerosol time-of-flight mass spectrometer were used to measure the products in the gas and particle phases in real-time.Experimental results demonstrated that ethylphenol,methylglyoxal,phenol,benzaldehyde,and 2-ethylfurane were the predominant photooxidation products in both the gas and particle phases.However,there were some differences between detected gas phase products and those of particle phase,for example,2-ethylfurane,ethylglyoxylie acid,nitroethylbenzene,3,4-dioxopentanal and ethyl-nitrophenol were only existing in the particle-phase.The possible reaction mechanisms leading to these products were also discussed and proposed.     

Ecophysiological responses of winter wheat seedling to aerosol wet deposition of Xi’an area, China

Aerosol leads to 30% reduction in solar radiation reaching the earth’s surface, and a similar reduction in crops yield for both wheat and rice. To determine the effect of aerosol wet deposition on crops, aerosol samples were collected in September, 2006 at Xi’an urban suburb (34?44 N, 109?49 E), and wheat seedlings were treated with aerosol of different concentrations in laboratory conditions. Changes in physiological and biochemical parameters of wheat seedlings were measured. In comparison with the control, the activities of superoxide dismudase (SOD) and catalase (CAT) and the concentration malondialdehyde (MDA) and oxidized glutathione (GSSG) of wheat seedlings increased progressively with increasing concentrations of added aerosol, while the opposite trend was seen for the activities of nitric oxide synthase (NOS), the concentrations of glutathione (GSH) and nitric oxide (NO), and the ratio of GSH/GSSG. When the seedlings were treated with the aerosol of 1 and 2 mg/L, the coleoptile elongation, shoot elongation and biomass accumulation were increased, the effect at treatment of 2 mg/L was most significant. However, aerosol treatments with rates of 3 and 4 mg/L resulted in a decrease in coleoptile elongation, shoot elongation and biomass accumulation in seedlings, and significant effect was for the treatment of 4 mg/L. Hence, lower concentrations of aerosol wet deposition were in favor of crops growth, but its higher concentrations could result in deleterious effects for crops and decreased crops growth.     

巷道内粉尘二次飞扬规律的数值模拟研究

针对巷道中沉积粉尘二次飞扬的现象,利用数值模拟的方法对粉尘二次飞扬进行了研究,分析了巷道内粉尘二次飞扬的极限风速与扬尘粒径之间的关系,从而为矿井通风除尘提供一定参考依据,给矿井工人创造良好的工作环境。     

Acute effects of chlorpyryphos-ethyl and secondary treated e uents on acetylcholinesterase and butyrylcholinesterase activities in Carcinus maenas

The acute effects of commercial formulation of chlorpyrifos-ethyl (Dursbanr®) and the secondary treated industrial/urban effluent (STIUE) exposure on acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) activities in hepatopancreas and gills of Mediterranean crab Carcinus maenas were investigated. After 2 d of exposure to chlorpyriphos-ethyl, the AChE activity was inhibited in both organs at concentrations of 3.12 and 7.82 μ/L, whereas the BuChE was inhibited only at higher concentration 7.82 μ/L of commercial preparation Dursbanr®. The exposure of crabs to Dursbanr® (3.12 μ/L) showed a significant decrement of AChE activity at 24 and 48 h, whereas the BuChE was inhibited only after 24 h and no inhibition for both enzymes was observed after 72 h. Moreover, a significant repression of AChE activity was observed in both organs of C. maenas exposed to 5% of STIUE. Our experiments indicated that the measurement of AChE activity in gills and hepatopancreas of C. maenas would be useful biomarker of organophosphorous (OP) and of neurotoxic effects of STIUE in Tunisia.