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841.
大同市空气中多环芳烃与人尿中1-羟基芘的分析 总被引:4,自引:0,他引:4
用GC~2/MS和HPLC鉴定出大同市空气中的多环芳烃化合物35种.对大同市不同功能区空气中苯并(a)芘(BaP)和人尿中1-羟基芘同步采样分析.结果表明,不同功能区BaP浓度有显著差别:采暖期浓度急剧增加,城区浓度为对照点的17倍,日均值达330ng/m~3.人尿中1-羟基芘的浓度与空气中BaP的浓度显著相关.采暖期城区尿中1-羟基芘的几何均值为1.86μmol/mol肌酐,非采暖期为1.14μmol/mol肌酐,均较北京市的均值高出五倍多.证明大同市由于直接燃煤,造成空气中多环芳烃的严重污染. 相似文献
842.
Protczak A Trzeszczynski J 《Environmental science and pollution research international》2002,9(6):377-380
In the last years, a continuous increase of the O3 concentration has been recorded in the lower atmospheric layers. Photochemical reactions with NO(x), CO and organic compounds are the main sources of O3 in the troposphere. In this work, an attempt was made to determine the impact of alkenes on the O3 concentration in the troposphere. A study on the gas-phase reactions of 03 with 1-hexene, 1-heptene and 1-nonene was made. The reactions were carried out at room temperature under atmospheric pressure. Ozone was formed by the ultraviolet radiation emitted by a mercury lamp, in order to simulate the atmospheric conditions. The changes with time in the concentration of O3, 1-alkenes and formed aldehydes were investigated. Qualitative and quantitative analyses were done by means of the gas chromatography and colorimetry. The following products were identified: pentanal from 1-hexene; hexanal from 1-heptene; oktanal from 1-nonene. For each of the reactions, HCHO was also determined as a product. The reaction rate constants were calculated and obtained in units of 10(-17) cm(-3) molecule(-1) s(-1): 1.94-0.99 for 1-hexene, 5.54-4.51 for 1-heptene and 1.54-0.76 for 1-nonene. Based on the results obtained, an explanation of O3 concentration variations in the planetary boundary layer can be given. Last year a considerable increase of O3 concentration on the roads of Western Europe was recorded. This increase could have resulted from the decrease of alkene concentration in the air due to common use of the catalytic converters in cars. The unsaturated hydrocarbons rapidly oxidize on the catalyst. In Eastern Europe, where the amount of cars equipped with catalytic converters is smaller than in Western Europe, the alkene content in the exhaust fumes results in a decrease of the O3 concentration in the troposphere. 相似文献
843.
844.
Professor D. J. H. Brock Lilias Barron Susan Holloway W. A. Liston S. G. Hillier M. Seppala 《黑龙江环境通报》1990,10(4):245-251
A set of 21 early maternal serum samples (19 first-trimester and two at 14 weeks) from pregnancies resulting in a child with Down syndrome was matched for gestation and length of storage with 63 samples from unaffected pregnancies. The concentrations of alpha-fetoprotein (AFP), unconjugated oestriol (uE3), human chorionic gonadotrophin (hCG), pregnancy-specific β1–glycoprotein (SP1), and placental alkaline phosphatase (PALP) were measured. The ratios of the medians for Down syndrome pregnancies compared with the medians for controls were AFP 0·71, uE3 0·67, hCG 1·43, SP1 0·79, and PALP 0·92. Although the differences between the medians for affected and unaffected pregnancies were not significant, the trends for AFP, uE3, and hCG confirm earlier findings on first-trimester samples. 相似文献
845.
AdiagnosticexperimentoftheinfluenceofCO_2onwinterwheatWangChunyi;BaiYueming;WenMin(ChineseAcadernyofMeteorologicalSciences,Be... 相似文献
846.
IntroductionThesolventextractionisoneofthemethodsfortreatmentofhighconcentrationwastewatercontainingphenol(Koreman,1978;Lanouett?.. 相似文献
847.
Lawrence E. Susskind 《Environmental Impact Assessment Review》1985,5(2):157-163
Traditional approaches to the siting of potentially hazardous but regionally necessary facilities are often ineffective and lead to drawn-out legal disputes ultimately satisfactory to none of the parties. Research at MIT over the last decade has indicated five factors that may solve the siting puzzle. Application of these principles do not guarantee that a decision will not be disputed but may enhance the possibility of a wise and durable agreement. 相似文献
848.
异烟酸-吡唑啉酮光度法测定氰化物的方法研究 总被引:1,自引:0,他引:1
研究了用次氯酸钠代替氯胺 T为活性氯试剂进行测定的方法 ,比较了这两种试剂对测定条件、结果的影响 ,且对蒸馏预处理方法进行了改进 ,并提出了在蒸馏预处理及异烟酸 -吡唑啉酮分光光度法测定过程中的注意事项 相似文献
849.
运用灰色系统理论建立灰色模型GM,对该模型进行了检验和残差修正。并用其模型分析和预测乌鲁木齐市1994=1998年大气降水pH值。 相似文献
850.