Mercury isotope variations in surface soils in different contaminated areas in Guizhou Province, China

Guizhou Province is known as a heavily Hg-polluted area in China due to its special geochemical background and complicated Hg emission sources.In this study,we investigated the Hg isotope compositions of surface soil samples in the Hg mining area,zinc smelting area,coal combustion area,which are known to be the typical pollution regions of Hg in this province.We also compared the Hg isotopic fingerprints of primary Hg sources,such as hydrothermal Hg-bearing ores,coals and atmospheric Hg samples.According to our study,Hg stored in surface soils in different pollution regions in Guizhou Province displays a wide range of both mass dependent fractionation(MDF,δ202Hg) and mass independent fractionation(MIF,△199Hg).δ 202 Hg varies by 2.0‰ and △199Hg varies by 0.25‰ in the investigated surface soils.This study demonstrated that using a "MDF-MIF" two dimensional Hg isotope system could be particularly useful in discriminating Hg sources in soils.     

Mercury speciation and spatial distribution in surface waters of the Yarlung Zangbo River,Tibet

The Yarlung Zangbo River is the highest river in the world. It flows from west to east through the southern part of Tibet. The mercury (Hg) speciation and distribution in surface waters and soils near the bank of the Yarlung Zangbo River and its two tribu-taries, the Lhasa and Niyang Rivers, were investigated in June 2007. Simultaneously, major water quality parameters were also measured at the same stations. Total Hg (THg) and total methylmercury (TMeHg) concentrations in surface waters of the Yarlung Zangbo River ranged from 1.46 to 4.99 ng/L and from 0.06 to 0.29 ng/L, respectively, representing the background levels in river systems of the Tibetan Plateau. Particulate Hg (PHg) accounted for 69% of the THg, and the two Hg species had a significant relationship (r=0.990, P<0.01). Approximately 61% of the spatial distribution of THg was controlled by the concentrations of total suspended particles (TSP). Reactive Hg (RHg) concentrations ranged from 0.10 to 0.36 ng/L, and this fraction may play a weak role in terms of the transport and fate of Hg in surface waters. Dissolved methylmercury (DMeHg) constituted 71% of the TMeHg and was significantly correlated with TMeHg (r=0.746, P<0.01). The spatial distribution of TMeHg is not strongly affected by environmental factors such as THg, RHg, temperature, pH, dissolved organic carbon (DOC), and TSP. In addition, the inflow of both the Lhasa and Niyang Rivers probably influences the concentrations of THg in surface waters of the mainstream, but such an effect is not obvious for TMeHg.     

负载型TiO2催化剂的制备及其酯交换反应性能

采用水解法制备负载型TiO2／SiO2催化剂,用于苯酚和草酸二甲酯酯交换反应．通过考察催化剂焙烧温 度、载体粒径、催化剂用量、活性组分负载量和反应时间等因素对该酯交换反应的影响,确定出较佳的催化剂制备 工艺及反应条件．负载型氧化钛催化剂在该酯交换反应中表现出活性好、选择性高、催化剂易分离回收等优点．以 550℃焙烧的TiO2／SiO2为酯交换催化剂,TiO2负载量为13％,反应时间2h,反应温度180℃,草酸二甲酯的转化 率、甲基苯基草酸酯和草酸二苯酯的选择性分别为53．1％、72．1％和27．3％．     

High-precision measurement of mercury isotope ratios of atmospheric deposition over the past 150 years recorded in a peat core taken from Hongyuan,Sichuan Province,China

High-precision 210Pb dating technology was applied to a peat core with a time span of about 150 years that was taken from Hongyuan, Sichuan Province, China. The concentrations of total mercury (Hg) and stable isotope compositions of mercury in the peat core were measured using a LUMEX 915 instrument and multi-collector inductively coupled plasma mass spectrometer, respectively. Total mercury (Hg) concentrations in the peat core had a clearly increasing trend from the bottom to top of the core while δ 202Hg ...     

Yb(OTF)3催化2,4-二氨基甲苯与碳酸二甲酯甲氧羰基化合成2,4-甲苯二氨基甲酸甲酯

研究了Yb（OTF），催化剂对2，4-二氨基甲苯（TDA）与碳酸二甲酯甲氧羰基化反应合成2，4-甲苯二氨基甲酸甲酯（TDC）的催化活性，考察了反应温度和反应时间对Yb（OTF），催化活性的影响。在该催化剂的作用下，反应温度453K，反应时间5h时TDA转化率可达100％，TDC的产率达到23、6％，同时考察了Yb（OTF）3催化剂的寿命，经4次重复使用催化剂基本不失活。Ln（OTF）3（Ln=La，Nd，Yb）催化活性的比较表明催化剂Lewis酸性的强弱与TDC的产率成正比。