海水痕量营养盐和金属的分子光谱分析方法研究进展

海洋现场观测是获取海洋环境研究数据的重要途径.鉴于海洋的现场环境严酷复杂,以及采集、储存和运输海水样品的困难,海洋化学参数的现场和原位检测一直为海洋学家所追求,成为海水分析技术的研究热点.通过综述近年来海水痕量营养盐和重要痕量金属的分子光谱分析方法的研究进展,从灵敏度和测定范围等方面,总结痕量营养盐（活性磷、亚硝氮、硝氮、铵态氮）和痕量金属（铁、锰、铜、铝）的分析技术,侧重于现场和原位测定方法,聚焦于分光光度法、荧光法和化学发光法等适用于海洋现场的光学检测方法的研究情况,同时展示这些方法及相应仪器在岸基实验室、船基实验室、海洋走航分析以及原位长期观测中的应用实例;并对现存的关键问题及可能的解决方案进行探讨,对本领域今后的发展方向做出展望.     

不同分子量草源DOM与重金属的相互作用

将采集自徒骇河聊城河段沉水植被生长区的DOM分为3个分子量级别：<0.7 μm DOM、<500 kDa DOM、<100 kDa DOM,通过三维荧光结合平行因子分析（EEM-PARAFAC）和荧光滴定法探讨水体中不同分子量DOM的荧光特征及其与重金属（Cu²⁺和Pb²⁺）的络合作用.结果表明：草源DOM的有机碳主要储存在分子量<100 kDa组分中.PARAFAC分析得出4个荧光组分,分别为类色氨酸组分C2、C4,以及酪氨酸组分C1和类腐殖质组分C3.草源DOM主要以分子量<100 kDa的类色氨酸组分C2和酪氨酸组分C1为主.二维相关光谱（2D-COS）表明,与类腐殖物质相比,类蛋白物质优先与Cu²⁺与Pb²⁺发生猝灭,DOM中不同分子量组分与Cu²⁺与Pb²⁺的猝灭顺序未发生改变.在与Cu²⁺结合的过程中,不同 分子量中类腐殖质组分C3的络合常数（logK_a）大于类蛋白组分C1、C2,表明类腐殖质组分的金属结合能力强于类蛋白质组分;随着分子量级别的降低,组分C3的logK_a值逐渐增大（3.47<3.59<3.73）,表明低分子量（<100 kDa）中的类腐殖质与Cu²⁺具有更高的结合能力.不同分子量DOM中,类蛋白组分C1、C2、C4在分子量<0.7 μm DOM中的logK_a值均最高,表明高分子量（<0.7 μm）的类蛋白质更容易与Cu²⁺结合,而Pb²⁺与各组分结合出现了荧光增强或猝灭的现象.DOM-Cu²⁺与DOM-Pb²⁺结合表现出不同的结合规律,反映出金属种类与DOM结合的异质性与复杂性.     

H-ZSM-5分子筛吸附-氧化NOx的研究

针对湿法脱硫后船舶尾气特点,考察了3种不同硅铝比的H-ZSM-5分子筛对船舶脱硫后尾气中NO_x的吸附-氧化过程及其影响因素,并采用TPD研究了干气下不同硅铝比的分子筛吸附饱和后的脱附情况.结果表明:干气条件下,硅铝比低的分子筛具有较好的吸附效果;硅铝比高的分子筛具有较好的抗水性,但从干气到饱和湿度下,硅铝比为300的分子筛的NO氧化率从36%降至18%;干气下,低温有利于分子筛的吸附-氧化;分子筛用量增加能够增加其对NO_x的吸附效果和氧化效果.TPD结果表明:NO和NO2共吸附在分子筛上,3种分子筛中脱附出的NO_x中NO2均占脱附总量的80%以上,但在600℃时,NO_x在分子筛上脱附仍不完全.     

雾天气下二次气溶胶均质成核生长过程

二次气溶胶的核化过程涉及分子杂乱运动和碰撞,在分子间的范德华力作用下,大气环境系统中产生分子聚合,形成分子团、胚胎和核.基于此建立二次气溶胶核化和生长模型,并且采用颗粒群平衡模拟和多重蒙特卡洛方法,对雾天气下水汽均质同分子核化及H₂O-H₂SO₄均质异分子核化的过程开展热力学和动力学数值研究. 结果表明:在水汽均质核化过程中,当水汽过饱和比从2增至10时,水汽的成核速率增加约73个数量级,形成临界胚胎所需的分子数降低了97.3%. 而对于H₂O-H₂SO₄均质异分子核化过程,在环境温度271.15 K,气态H₂SO₄分子数浓度为5×107cm-3条件下,当RH(相对湿度)由80%增至100%时,二次气溶胶成核速率增加1.4倍;在气态H₂SO₄分子数浓度较高、RH较大时,核化形成的临界胚胎粒径较小. 经过均质核化生长后,二次气溶胶粒径处于1.5～3.5 nm.      

Online single particle analysis of chemical composition and mixing state of crop straw burning particles: from laboratory study to field measurement

Fresh straw burning (SB) particles were generated in the laboratory by the combustion of rice straw and corn straw. The chemical composition and mixing state of the fresh SB particles were investigated by an Aerosol Time-of-Flight Mass Spectrometer (ATOFMS). Based on the mass spectral patterns, the SB particles were clustered into four major types: Salt, Organic Carbon (OC), Elemental Carbon (EC), and internally mixed particles of EC and OC (EC-OC). In addition, particles containing ash, polycyclic aromatic hydrocarbons, heavy metals or nicotine were also observed. Physical and chemical changes of the SB particles immediately after the emission were analyzed with highly time-resolved data. During the aging processes, the average particle size increased steadily. Freshly emitted organic compounds were gradually oxidized to more oxygenated compounds in the OC-containing particles. Meanwhile, an important displacement reaction (2KCl+ SO42−→ K₂SO₄ + 2Cl⁻) was observed. The marker ions for SB particles were optimized and applied to identify the SB particles in the ambient atmosphere. The fluctuation of the number fraction of ambient SB particles sorted by ATOFMS agrees well with that of water soluble K⁺ measured by an online ion chromatography, demonstrating that the optimized marker ions could be good tracers for SB particles in field measurements.     

Trace metals used as natural markers for discriminating some karstic freshwaters near Trieste (Italy)

Some heavy metals have been determined using voltammetry in freshwaters forming part of a karstic hydrological system (the Timavo River, north of Trieste), during attempts to characterize and discriminate the different sources of the springs. The trace elements can be considered natural markers, with lead appearing to be the most discriminating variable. Non parametric statistics and cluster analysis were used to estimate the significance of the determined parameters with respect to the considered ecosystem.     

Acute effects of low-dose cypermethrin on male rat cells

Effects of synthetic pyrethroid insecticide α-cypermethrin were investigated following intradermal dose (5–50 mM) of cypermethrin to male albino Wistar rats. Glucose, protein, cholesterol, triglycerides, urea, uric acid, creatinine, hemoglobin, blood RBC, and WBC content were determined 6 h after pesticide administration. Biochemical parameters and blood cell count changed significantly in treated rats at all doses. Low-dose cypermethrin affected early biochemical changes in rats.     

土壤中抗生素的生态毒性及其分子生物标志物技术的研究进展

抗生素作为抑菌或杀菌药物被广泛应用于畜禽养殖中。不能完全被机体吸收的抗生素经由畜禽排泄物直接进入环境。随着耐药基因和超级病菌的出现,抗生素产生的环境问题引起了广泛关注。土壤是环境中抗生素最主要的累积场所之一,对土壤中抗生素的生态毒性及其分子生物指示指标的研究具有重要意义。本文在总结国内外相关研究的基础上,阐述了抗生素对土壤中微生物、动物和植物所产生的毒性以及分子生物标志物在土壤抗生素污染研究中的应用,并对未来的研究工作进行了展望。     

Hepatitis B virus infection among health care workers in Public Teaching Hospitals in Khartoum State, Sudan

Background

Hepatitis B virus (HBV) infection is a global public health problem. It is estimated that there are more than 300 million HBV carriers in the world.

Aim

The study aimed to examine the sero-prevalence of hepatitis B virus (HBV) markers among health care workers (HCWs) in Public Teaching Hospitals in Khartoum State, in the year 2004.

Methods

The study is an observational, cross sectional, facility-based study. It was conducted on stratified two-stage cluster random sample of 843 subjects. The study followed non-parametric statistical methods, using Z-test for single proportion.

Results

Among the 843 subjects tested for all HBV markers (Anti-HBc, HBsAg, HBsAb, and HBeAg), the prevalence of Anti-HBc, HBsAg, HBsAb, and HBeAg was found to be 57% (CI 95%:53-60%), 6% (CI 95%:4.0-8.0%), 37% (CI 95%:34-40%) and 9% (CI 95%:7-11%) respectively. P < 0.05.

Conclusion

Seroprevalence of all HBV markers (P < 0.05) was found to be significantly high, while the rate of immunity against HBV infection was low among health care workers In Public Teaching Hospitals in Khartoum State, Sudan.     

聚氨酯合成革厂空气中挥发性有机物的成分谱

采用吸附管采样和二次热解吸-GC-MSD联用技术研究了珠江三角洲地区3个典型聚氨酯(PU)合成革厂不同车间空气中挥发性有机物(VOCs)的含量和成分谱.结果表明,主要检出卤代烃、氯苯类、芳香烃类、酯类、酰胺类和酮类等6类共15种VOCs化合物,其中生产车间VOCs总浓度高达(15.300±0.964)mg/m3,而半成品车间、树脂原料车间和厂边界分别为(12.047±0.977)mg/m3,(1.912±1.281)mg/m3, (1.980±0.522)mg/m3;生产车间和半成品车间的VOCs特征轮廓图谱较相似,特征化合物均为甲苯、乙酸乙酯和2-丁酮;而树脂原料车间的特征化合物为甲苯、苯和苯乙烯.源成分谱研究得出该类污染源排放的VOCs分子标志物为乙酸乙酯,其百分比含量最高,达到36.32%± 16.62%.