Element-Enrichment Factors in Lichens from Terceira, Santa Maria and Madeira Islands (Azores and Madeira Archipelagoes)

In this study, more than 20 minor and trace elements have been determined by INAA (instrumental neutron activation analysis), in different species of lichens in three Portuguese islands of the Central North Atlantic (Santa Maria, Terceira, and Madeira Islands). The foliose species Parmotrema bangii, Parmotrema robustum, Parmotrema crinitum, Flavoparmelia caperata, Platismatia glauca, and the fruiticose species Ramalina canariensis, Ramalina farinacea, Ramalina implectens, Ramalina pusilla, Cladonia furcata, Cladonia coniocraea, Usnea dasaea, Usnea esperantiana, were the collected species. Samples of superficial soils were also collected and the fraction below 64 m was analysed. The enrichment factors relative to this fraction using Al as the normalising element were calculated. Fruiticose and foliose lichens displayed different EF values concerning bromine and potassium. The first was more enriched in the foliose species while the latter was more enriched in the fruiticose species and was assigned to the physiological response. Enrichment was found for Mg, Cs, As, Hg, Na, Zn, and Cl, in all the species. Lichen-based concentration patterns were shown for Na, Al, Cl, Br, Sb, Ce, and Hg and compared to similar patterns in Portugal mainland. In general, the patterns compared well except for Cl, Na, and Br. Background levels of the epiphytic lichens collected in the islands were obtained.     

An Examination of the Oxidation of Elemental Mercury in the Presence of Halide Surfaces

Recent field investigations in polar regions, and over the ocean, have suggested that elemental mercury (Hg⁰) can be photochemically oxidized in the presence of reactive halogen species that are formed in the presence of salt particles, typically through a reactive catalytic cycle involving ozone destruction. Furthermore, these studies have suggested that the Hg⁰ oxidation reaction involves the reaction with reactive bromine species such as Br, BrO, and Br₂. To investigate these reactions in more detail, we performed experiments using a quartz reactive chamber so that the oxidation of Hg⁰, and the formation of ionic Hg products, could be examined in detail under different reaction scenarios, but at realistic levels of Hg. To examine if the reactions were enhanced by the presence of deliquescent salt surfaces, as has been postulated to be the case for the formation of reactive halogens, one surface of the cell was coated with either NaCl or NaBr for some experiments. In addition to laboratory experiments with a Xenon lamp, outdoor experiments under natural light were also conducted. The results of these studies showed that oxidation of Hg⁰ did not occur in the dark, except in the presence of a deliquescent NaBr salt surface. The rate of oxidation was slow in the absence of salt surfaces, and in the absence of low wavelength light (<324 nm). In the presence of NaCl surfaces, oxidation rates were at least two orders of magnitude faster, but the rate was further increased in the presence of NaBr, by a further factor of 25. With outdoor light, while the rates of oxidation were lower, the results were similar overall. The results are discussed in terms of the reactions occurring and the mechanisms of Hg⁰ oxidation. Finally, the implications of these reactions to the overall global Hg cycle are discussed.     

Vertical distribution of phosphorus and P-dissolving/decomposing bacteria in the sediment of Guanting reservoir

In this study, we determined pH, phosphorus content and the number of P-dis- solving/decomposing bacteria in relation to the depth in the sediment of Guanting reservoir in Beijing. The pH value was slightly increased from 8.0 in the surface to 8.5 in the bottle (69 cm in depth) of sediment. The highest P content, 1269 mg/kg, was detected in the 35 cm layer, followed by the 5 cm (993 mg/kg) and 69 cm (580 mg/kg) layers. The number of inorganic P-dissolving bacteria varied from 6(102 to 8(104 and the organic P-discomposing bacteria were from 1.9(103 to 6.3(104 per gram sediment in different depths, which were counted under 28℃ and 20℃ ( pH7.5 and 8.5. The number of P-dissolving/discomposing bacteria was directly correlated to the P content in each layer of sediments. The analysis of P-dissolving/decomposing ability of bacteria showed that some of these bacteria were also capable of accumulating P intracellularly. The intracellular P-accumulation was more efficient at lower temperature; in contrast, the activity of P-dissolving/decomposing was stronger at higher temperature. So the content of dissolved P in water body, or quality of water, could be affected by the change of temperature via the regulation of bacterial activity. On the basis of 16S rDNA sequencing, the 13 efficient P-dis- solving/decomposing bacteria were identified as Bacillus spp., Bacterium sp., Microbacterium sp., Paenibacillus sp. and Pseudomonas sp.     

芽孢杆菌HBS4还原亚硒酸钠为单质硒的实验研究

利用从油藏中分离的芽孢杆菌HBS4在兼性厌氧情况下作用于剧毒物质亚硒酸钠,36 h后1～11mM的样品中均出现了大量红色颗粒沉淀物.生物显微镜观察发现,在很多细菌内部出现一颗到多颗红色的圆形颗粒,排列方式有单链、双链、弧线和无规则排列,并且在细胞周围释放有游离态的红色颗粒.XPS测试红色沉淀物发现四价硒全部还原为零价硒.实验还发现添加葡萄糖对单质硒的产量有很大的促进作用.     

Fourier-transform Infrared Spectroscopy (FTIRS), a New Method to Infer Past Changes in Tree-line Position and TOC using Lake Sediment

This study tests the hypothesis that Fourier-transform infrared spectroscopy (FTIRS) of lake sediments can be used to infer past changes in tree-line position and total organic carbon (TOC) content of lake water. A training set of 100 lakes from northern Sweden spanning a broad altitudinal and TOC gradient from 0.7 to 14.9 mg/l was used to assess whether vegetation zones and TOC can be modelled from FTIR spectra of surface sediments (0–1 cm) using principal component analysis (PCA) and partial least squares (PLS) regression. Preliminary results show that FTIRS of lake sediments can be used to reconstruct past changes in tree line and the TOC content of lake water, which is hardly surprising since FTIRS registers the properties of organic and minerogenic material derived from the water mass and the drainage area. The FTIRS model for TOC gives a root mean squared error (RMSECV) of calibration of 1.4 mg/l (10% of the gradient) assessed by internal cross-validation (CV) yielding an R_cv² of 0.64. This should be compared with a near-infrared spectroscopy (NIRS) and diatom transfer function for TOC from the same set of lakes, which have a R_cv² of 0.61 and 0.31, and RMSECV of 1.6 and 2.3 mg/l, respectively. The FTIRS-TOC model was applied to a Holocene sediment core from a tree-line lake and the results show similar trends as inferences from NIRS and pollen from the same core. Overall, the results indicate that changes in FTIR spectra from lake sediments reflect differences in catchment vegetation and TOC, and that FTIRS-models based on surface-sediment samples can be applied to sediment cores for retrospective analysis.     

High exposure of Chinese mercury mine workers to elemental mercury vapor and their increased hair methylmercury levels： A preliminary report

Objectives： To assess the exposure to elemental mercury （Hg0） vapor and methylmercury （MeHg） among mercury mine workers in an area of Guizhou Province, China. Methods： Urine total mercury （THg） and hair THg and MeHg were measured in 26 mercury miners and smelters （i.e., exposed group）, and 52 control subjects （unexposed group）. Results： The mine workers showed high geometric mean THg concentrations in urine （258 ng/mL, 226 μg/g creatinine） and hair （20.0 μg/g）. The urine Hg level of smelters, in particular, was extremely high （338 μg/g creatinine in urine）. The highest urine THg reached 4580 μg/g creatinine. THg concentrations in urine and hair showed a significant correlation in the exposed group （r=0.62）, indicating the adhesion of HgO vapor to hair. However, no such significant correlation was found in the control group.     

安徽蒙城尉迟寺遗址地层的磁化率与元素地球化学记录研究

通过磁化率和地球化学元素的因子分析法和比值法分析提取出尉迟寺遗址地层记录的环境演变信息。本区5050aBP以前的新石器时期为暖湿的气候环境;大汶口文化阶段气候总体偏干冷,存在数次波动;从大汶口至龙山文化期间,本区气候发生了较为明显的变化,由干冷转向温湿,这为水稻生产提供了有利条件,也促进了龙山文化的繁荣。在5050aBP之前及4620aBP、4700aBP前后可能都发生过冷干事件。     

土壤圈在全球变化中的意义与研究内容

土壤圈是地圈系统的重要组成部分，它处于地圈系统，即气圈、水圈、生物圈与岩石圈的交界面，是最活跃、最富生命力的圈层。土壤圈的物质循环是全球变化中物质循环的重要内容，因此，研究土壤圈及其物质循环的结构与功能，对全球变化，特别对全球土壤变化有密切关系。土壤圈在全球土壤变化中的研究内容包括：土壤圈与地圈各圈层的物质循环；水土资源的时空变化；土壤肥力变化与农业持续发展，区域治理与环境建设等，这些都是全球土壤变化，特别是中国全球变化的主题，应引起高度重视。     

Reconstructing the iron cycle from the horizontal distribution of metals in the sediment of Baldeggersee

In Baldeggersee, the distributions of solid phase Fe, Mn, V, Cr, As and Mo were determined in different sediment strata, deposited under various deep-water oxygen conditions. Iron concentrations are correlated with water depth when an anoxic sediment is in contact with an oxic water column. Benthic redox gradients trigger iron transport towards the deepest site (geochemical focusing) and loss of iron from the shallower parts through the outflow. Fe cycling in the lake is inhibited by oxygen penetration into the sediment. Vanadium and arsenic can be used as tracers for the internal Fe cycle. Their distribution patterns are highly correlated with iron. In case of a stable oxycline in the deep water, Mo is enriched in the sediment and correlates with Mn. The horizontal distribution patterns of Fe, V, As and the correlation of Fe and Mn with trace metals are promising proxy indicators for the reconstruction of deep-water oxygen conditions during deposition.