水库对乌江河流汞生物地球化学循环的影响

本论文的主要研究内容有以下三个方面：（1）蒸馏一乙基化GC-CVAFS法测定天然水体中甲基汞方法的建立及应用；（2）乌江表层河水不同形态汞分布特征的研究；（3）以乌江中上游干流不同年龄水库（乌江渡水库和东风水库）为例，探讨水库对乌江河流汞输送的影响及水库内汞的迁移转化。通过本论文的研究，取得以下成果：1．建立了一种基于蒸馏一乙基化结合气相色谱（GC）一冷原子荧光（CVAFS）测定天然水体中甲基汞的分析方法。水样中甲基汞经蒸馏后与四乙基硼化钠反应生成挥发性的甲基乙基汞，由氮气吹扫捕集于Tenax管，然后由GC-CVAFS测定。该方法的回收率为88.2％-108.4％，平均相对标准偏差为5．4％。取45mL水样测定，方法的最低检出限为0.009ng/L。该方法能准确测定天然水体中甲基汞的含量，步骤简洁、快速，明显优于国内目前使用的其余测定水体甲基汞的方法。2．乌江表层河水总汞的浓度分别为：丰水期659ng/L，枯水期16.9ng/L，明显高于北美和欧洲一些没受污染的河流，表明乌江流域已存在一定程度的污染。乌江河水汞的主要形态为颗粒态汞，其占总汞的比例为丰水期84％，枯水期占52％，乌江河流汞的分布、迁移行为主要受颗粒态物质控制。3．根据输入一输出通量模型，估算出东风水库总汞净通量为-57785.1g/yr，占总汞输入量的40.2％；乌江渡水库总汞净通量为-23273.7g/yr，占总汞输入量的14.0％，两个水库都表现为总汞的“汇”。与总汞相反，两个水库都表现为甲基汞的“源”，东风水库甲基汞净通量为+284.7g/yr，占甲基汞总输入量的4.4％；乌江渡水库甲基汞的净通量为＋6622.0g/yr，占甲基汞总输入量的80.1％。乌江渡水库甲基汞的“源”作用显著大于东风水库。4．乌江渡水库和东风水库水体总汞和甲基汞都呈现明显的季节变化，表现为春季＞冬季、夏季。乌江渡水库水体总汞平均为冬季9.0ng/L、春季16.0ng/L、夏季7.9ng/L；东风水库水体总汞平均为冬季8.2ng/L、春季12.5ng/L、夏季9.4ng/L。水体甲基汞的平均值分别为：乌江渡水库冬季0.74ng/L、春季0.97ng/L夏季0．89ng/L；东风水库冬季0.74ng/L、春季1.12ng/L、夏季0.38ng/L。水库水体甲基汞与总汞之间有相关关系，但未达极显著水平（乌江渡水库，r=0.451*，n=24；东风水库，r=0.471*，n＝27）。水库内汞和甲基汞的形态、含量以及分布受外源性输入、降水稀释、水库初级生产力水平以及水库运行方式等因素控制。5．乌江渡水库和东风水库沉积物总汞明显高于其它未受污染地区水库沉积物总汞。乌江渡水库沉积物总汞含量为254.7±44.3ng/g，东风水库沉积物总汞为171.0±23.0ng/g。两个水库沉积物总汞没有季节变化，且在沉积物垂直剖面上也没有明显的浓度梯度变化。与总汞相反，两个水库沉积物甲基汞在垂直剖面上有明显的梯度变化和季节变化。无机汞的甲基化作用主要发生在沉积物表层5cm以内。沉积物中甲基汞含量受微生物活性影响显著，通常在水库生物生产量和营养物输入量较大时甲基汞浓度也较高。沉积物甲基汞含量在两个水库都表现为冬季＜春季＜夏季，甲基汞含量以及甲基汞占总汞的比例为东风水库＜乌江渡水库。6．沉积物间隙水中无机汞的含量没有显著的季节变化；与此相反，沉积物间隙水中甲基汞浓度表现出明显的季节变化。沉积物间隙水中甲基汞在垂直剖面上的分布趋势与沉积物中甲基汞的分布趋势相一致，沉积物间隙水中甲基汞含量与沉积物中甲基汞含量呈显著性相关（乌江渡水库，r=0.770**，n＝75；东风水库，r＝0.675**,n＝75）。7．沉积物间隙水中无机汞和甲基汞是水体中无机汞和甲基汞的“源，，i但对乌江渡水库和东风水库而言，由于水体深度较大，水力停留时间较短，间隙水中扩散出来的甲基汞和无机汞对水库内水体中相应形态汞含量的影响程度有限。但这种影响作用为甲基汞＞无机汞，乌江渡水库＞东风水库。8．因采集的鱼多为人工饲养鱼（生长速度快、食物链短），两个水库鱼体总汞和甲基汞含量均低于国家食用标准。但乌江渡水库鱼体甲基汞含量以及甲基汞占总汞的比例均高于东风水库。可见，乌江流域水库鱼体甲基汞含量不取决于水库年龄，而受水库内水生食物链底端食物中甲基汞的含量控制。9．通过本论文的研究，得出由于被淹没土壤有机质含量较低，乌江流域水库无机汞甲基化的驱动力为水库内源性输入有机质。在一定的时间范围内，随着水库的发育，水库初级生产力水平的提高，内源性有机质输入量增加，会显著促进沉积物中无机汞的甲基化进程。

长江水环境的地球化学初步研究

1）长江沿程水溶态#delta#~(34)SO~(2-)_4的变化范围为-3.474～+5.938 per thousand，算术平均值为2.254 per thousand；悬浮态#delta#~(34)S之间的变化范围为-4.031 approx +4.580 per thousand。长江中水溶态#delta#~(34)SO~(2-)_4与悬浮态#delta#~(34)S之间存在相关性；2）根据长江中水溶态#delta#~(34)SO~(2-)_4的平均和它的径流量，估算中国河流#delta#~(34)SO~(2-)_4的加权平均值为+2.7 per thousand。结合中国长江、黄河的硫同位素组成和亚洲其它主要河流水溶态SO~(2-)_4的含量，推测亚洲河流的#delta#~(34)SO~(2-)_4加权平均值可能为+5 per thousand；3）长江流域内的区域地质条件决定了河流悬浮物中稀土元素和微量元素的背景含量－－悬浮物中稀土元素和大多数微量元素的含量为东高西低；4）悬浮物中大多数元素的含量随时间的变化基本保护不变，其变化幅度在自然波动范围之内；而砷元素在悬浮物中的含量随时间有明显的增高趋势，这显示了长江流域内的As污染源的增加。

Heat capacities of Al62.5Cu25Fe12.5 quasicrystals and B2 related crystals

The heat capacities of two Al62.5Cu25Fe12.5 samples containing icosahedral quasicrystals and B2 related crystals respectively were measured with a high-precision automatic adiabatic calorimeter over the temperature range of 75-385 K. The heat capacities of both samples increase with temperature. At the low temperature range, the heat capacity of the quasicrystalline sample is higher than that of the B2 approximate. However, the heat capacity of the B2 sample becomes higher above 254.987 K. (C) 1999 Elsevier Science B.V. All rights reserved.

Coleta e criação da lagarta-da-erva-mate, para estudos em laboratório.

2010

Informações meteorológicas de Passo Fundo, RS: janeiro de 2009.

2009

Constructing a myth of purity: the marketing of Welsh water

Roberts, Owen. 'Constructing a myth of purity: the marketing of Welsh water', in: 'A history of Water. Vol. iii: the world of water', (London: I.B. Tauris, 2006), pp.254-268 RAE2008

Quantum Flows as Markovian Limit of Emission, Absorption and Scattering Interactions

Gough, John, (2004) 'Quantum Flows as Markovian Limit of Emission, Absorption and Scattering Interactions', Communications in Mathematical Physics 254 pp.498-512 RAE2008

„Wielka gra” w rozważaniach Josepha Nye’a

W artykule dokonana została analiza percepcji potęgi amerykańskiej wg Josepha Nye’a. Przyrównuje on glob ziemski do Globalnej Szachownicy, na której ma miejsce Wielka Gra, pomiędzy jej uczestnikami. Owa gra toczy się na trzech równoległych płaszczyznach: sektorze siły militarnej, potencjale ekonomicznym oraz „miękkiej sile”. Te trzy sektory tworzą smart power, czyli rozważną potęgę. Zatem każde państwo, jak również pozapaństwowi uczestnicy stosunków międzynarodowych, posiada te trzy zasoby. Jednakże, można ich używać w przeróżny sposób, często nadużywając siły militarnej, kosztem „miękkiego oddziaływania politycznego”. Nie prowadzi to do rozważnej siły, a więc również nie zwiększa bezpieczeństwa na arenie międzynarodowej.

Muestras de productos con y sin esmaltado, elaborados en Guatavita.

19 hojas : ilustraciones, fotografías

Visualising ribosome profiling and using it for reading frame detection and exploration of eukaryotic translation initiation

Ribosome profiling (ribo-seq) is a recently developed technique that provides genomewide information on protein synthesis (GWIPS) in vivo. The high resolution of ribo-seq is one of the exciting properties of this technique. In Chapter 2, I present a computational method that utilises the sub-codon precision and triplet periodicity of ribosome profiling data to detect transitions in the translated reading frame. Application of this method to ribosome profiling data generated for human HeLa cells allowed us to detect several human genes where the same genomic segment is translated in more than one reading frame. Since the initial publication of the ribosome profiling technique in 2009, there has been a proliferation of studies that have used the technique to explore various questions with respect to translation. A review of the many uses and adaptations of the technique is provided in Chapter 1. Indeed, owing to the increasing popularity of the technique and the growing number of published ribosome profiling datasets, we have developed GWIPS-viz (http://gwips.ucc.ie), a ribo-seq dedicated genome browser. Details on the development of the browser and its usage are provided in Chapter 3. One of the surprising findings of ribosome profiling of initiating ribosomes carried out in 3 independent studies, was the widespread use of non-AUG codons as translation initiation start sites in mammals. Although initiation at non-AUG codons in mammals has been documented for some time, the extent of non-AUG initiation reported by these ribo-seq studies was unexpected. In Chapter 4, I present an approach for estimating the strength of initiating codons based on the leaky scanning model of translation initiation. Application of this approach to ribo-seq data illustrates that initiation at non-AUG codons is inefficient compared to initiation at AUG codons. In addition, our approach provides a probability of initiation score for each start site that allows its strength of initiation to be evaluated.