砷形态在湖水中垂直分布的研究

本文以天津水上公园湖泊作为研究现场，通过采样分析，研究了湖水中砷酸盐、亚砷酸盐、一甲基胂酸盐和二甲基胂酸盐的垂直分布及其影响因素。结果表明水上公园湖泊中砷酸盐是溶解态砷的主要存在形式，其垂直分布与悬浮物、叶绿素ａ、磷酸盐的浓度、水文等诸因素密切相关；一甲基胂酸盐含量保持相对稳定；光致转化是影响水中亚砷酸盐垂直分布差异的一个因素。     

大同盆地富砷地下水的水化学与地球化学研究

为弄清大同盆地地下水中影响砷的迁移、富集的主要地球化学与生物地球化学过程,为区域供水安全提供指导作用,针对高砷地下水系统开展了水文地球化学与含水层沉积物全岩地球化学研究;并在此基础上探讨了研究区高砷地下水成因。结果表明,研究区高砷地下水为偏碱性、强还原环境,砷含量为0.31～452μg·L-1,主要以砷酸盐形式存在,地下水中砷与三价铁的浓度有显著的相关性。高砷含水层沉积物中有机质、铁与砷含量表现出显著相关性。以上结果说明,碱性还原环境有利于地下水中砷的富集;微生物参与下,沉积物相有机质的氧化和Fe氧化物/氢氧化物的还原过程是本区高砷地下水形成的主控因素。     

天然湖水表面微层砷,磷酸盐,悬浮颗粒物及藻类富集现象的研究

本文利用自制的玻璃板表面微层水采样器采集并分析了天津水上公园湖水表面微层中砷的四种不同形态：亚砷酸盐、砷酸盐、一甲基刖酸盐、二甲基刖酸盐，以及溶解态总磷、总磷、县浮颗粒物和藻类的富集情况，初步探讨了它们在湖水表面微层富集的原因，结果表明，它们在湖水表面微层中均有不同程度的富集现象，其中以总磷、悬浮颗粒物和藻类尤为明显，它们在湖水表面微层的富集除了也大气物理运动过程的生物活动有关外，还与采样站位有关     

植物砷吸收与代谢的研究进展

砷(As)作为一种植物非必需的类金属元素广泛存在于自然界中,砷过量摄人不仅会对植物生长产生毒害作用,而且在植物的可食部位累积并通过食物链对人体健康构成威胁.生长介质中的砷酸盐(五价砷)一般是通过磷酸盐转运蛋白被植物吸收的,而亚砷酸(三价砷)和没有解离的甲基化砷则主要是通过质膜上的水通道蛋白被植物吸收的.在植物体内五价砷...     

芳烃混合物溶解规律的研究

本文利用双波长紫外分光光度法测定了多种组成的芳烃混合物在水相的溶解度,发现有机相中共存物质的组成及相互作用对它们各自的水溶解度具有重要影响。实验表明:液-液混合物表现出接近理想溶液的溶解行为;固-固混合物的溶解行为比较复杂,结构相近的固-固混合物的溶解行为接近理想溶液,而结构不相近的固-固混合物中各组份的溶解度与纯物质的溶解度接近;完全相溶的液-固混合物经固/液逸度比校正后,表现出接近理想溶液的溶解行为,本文还利用UNIFAC官能团法估算了芳烃混合物的溶解度,理论预测和实验值吻合很好。     

反相色谱-电感耦合等离子体质谱联用技术快速测定大米中无机砷

建立了反相高效液相色谱-电感耦合等离子体质谱联用技术(HPLC-ICPMS)测定大米中砷酸盐、亚砷酸盐、一甲基砷酸和二甲基砷酸的分析方法.采用安捷伦Zorbax SB-Aq色谱柱,使用己烷磺酸钠/柠檬酸体系为流动相,结合反向色谱的快速分离特点在4 min内完成5种砷形态化合物的分离.进样量为5μg·L-1时,砷酸盐、一甲基砷酸、亚砷酸盐、二甲基砷酸和砷甜菜碱对应的检出限分别为0.095、0.108、0.153、0.230、0.590μg·L-1.1.0μg·L-1的混合标准溶液连续测定10次,5种砷形态化合物的峰面积相对标准偏差(RSD)分别为2.8%、3.0%、3.0%、3.2%和3.5%.     

不同施肥处理对水稻根表铁和砷形态的影响

采用XAFS研究盆栽试验砷污染土壤中添加不同肥料后,苗期水稻根表铁膜和砷的矿物学特征.Fe的K边EXAFS谱表明,铁膜主要由2-line水铁矿组成,还有少部分针铁矿和赤铁矿等晶体矿;As的EXAFS谱显示,除了KNO3和K2SO4处理外,其余处理的铁膜中砷以三价砷为主.KNO3处理显著减少了水稻根表铁膜的形成,而且抑制了水稻对砷的吸收.不同的肥料可以影响铁膜中砷的存在形态.     

沉积物间隙水溶解态磷和铁（Ⅱ）高分辨同步分析方法的研究

沉积物具有高度的空间异质性,尤其在沉积物-水界面附近的微环境中,溶质在微小尺度上可能存在强烈的浓度梯度分布,需要借助高分辨的获取技术才能表征。本研究发展了一种沉积物微界面溶解态反应性磷（Dissolved Reactive Phosphorus,DRP）和溶解态铁（Ⅱ）的同步分析方法。利用分辨率为4 mm、平衡时间仅为2 d的微型间隙水平衡装置（Peeper装置）获取微量间隙水（～100μL·样品-1）,采用384微孔板微量比色法分别测定同一间隙水样品中的DRP和溶解态铁（Ⅱ）的质量浓度,单一指标所消耗的间隙水体积由5 mL减少到仅～40μL,检出限分别为0.009和0.017 mg·L-1,精密度为1%～7%,均与常规方法相近。将该分析方法应用到太湖两个湖区的沉积物中,同步获得的微界面溶解态磷和铁（Ⅱ）的分布较好地反映了两者的关系。     

砷胁迫下水磷耦合对不同磷效率水稻根表铁膜及其各部位砷含量的影响

为探索缓解水稻砷毒害的农艺措施,以耐低磷水稻99011和低磷敏感水稻99012为材料,通过土培试验,研究水分、磷用量及其交互作用对不同砷浓度酸性土壤中水稻根表铁膜以及植物体内砷分配的影响。结果表明,节水灌溉(干湿交替)明显减少水稻根表铁膜量,降低铁膜、根系、秸秆、颖壳和精米中的砷含量。与30mg·kg-1P2O5相比,180mg·kg-1P2O5能明显减少两个品种水稻的根表铁膜量以及根系和秸秆中的砷含量;对耐低磷品种铁膜砷含量影响不大,但显著降低磷敏感品种铁膜砷含量;在50mg·kg-1砷处理中增加磷用量对水稻颖壳砷含量影响不大,在100mg·kg-1砷处理时能显著降低颖壳砷含量;增加磷用量可明显增加耐低磷品种的精米砷含量,降低磷敏感品种的精米砷含量。水、磷交互效应主要受水分效应的影响。加砷处理后,相同处理下耐低磷品种的根表铁膜量和铁膜中的砷含量显著高于磷敏感品种,而根系、秸秆、颖壳和精米中的砷含量则相反。研究表明,可以通过节水灌溉,并根据砷污染程度和植物磷营养特性确定适当的磷肥用量,从而减少砷在水稻体内的累积,提高食品安全。     

地下水砷污染形成机制研究进展

地下水砷污染是全球饮用水的主要威胁之一,目前全世界有超过一亿人受砷污染地下水问题的困扰.因此,深入研究地下水砷污染的形成机制,对预测地下水中砷的分布及解决地下水砷污染问题具有重要意义.本文在归纳总结前人相关研究的基础上,综述了关于地下水砷污染形成机制的不同解释及最新研究进展,重点阐述了铁氧化物还原溶解释放砷机制,并详细...     

In vitro assessment of arsenic mobility in historical mine waste dust using simulated lung fluid

Exposure studies have linked arsenic (As) ingestion with disease in mining-affected populations; however, inhalation of mine waste dust as a pathway for pulmonary toxicity and systemic absorption has received limited attention. A biologically relevant extractant was used to assess the 24-h lung bioaccessibility of As in dust isolated from four distinct types of historical gold mine wastes common to regional Victoria, Australia. Mine waste particles less than 20 µm in size (PM₂₀) were incubated in a simulated lung fluid containing a major surface-active component found in mammalian lungs, dipalmitoylphosphatidylcholine. The supernatants were extracted, and their As contents measured after 1, 2, 4, 8 and 24 h. The resultant As solubility profiles show rapid dissolution followed by a more modest increasing trend, with between 75 and 82% of the total 24-h bioaccessible As released within the first 8 h. These profiles are consistent with the solubility profile of scorodite, a secondary As-bearing phase detected by X-ray diffraction in one of the investigated waste materials. Compared with similar studies, the cumulative As concentrations released at the 24-h time point were extremely low (range 297 ± 6–3983 ± 396 µg L^?1), representing between 0.020 ± 0.002 and 0.036 ± 0.003% of the total As in the PM₂₀.     

Rate of dissolution of diatom silica walls in seawater

The solubility and dissolution rate of silica were investigated using cell walls prepared from two species of diatoms, Thalassiosira decipiens and Rhizosolenia hebetata forma semispina. The solubility (C _e) as a function of temperature (T, °C) can be described by the following equation: C _e (SiO₂ mg l^-1)=67.8+1.48 T. The first-order reaction equation without the surface-area term was considered to be reasonable in estimating the dissolution rate of biogenic silica in the ocean system. The rate of dissolution differed not only from one species to another but also from one portion to another portion of the same wall. The rate constants of dissolution in the ocean system were estimated to range in the order of from 10^-1 to 10^-9 per hour.     

铬酸钠晶体中铝酸钠杂质的分离

重点研究了含有杂质氢氧化钠和铝酸钠的酸钠晶体中铬酸钠和铝酸钠溶解动力学，洗涤一定组成的混合晶体的结果表明，两者在溶解动学方面具有很大差别，铬酸钠能迅速达到溶解平衡，而铝酸钠极易形成过程饱和溶液，且有一定的稳定性。     

Dissolution behavior of metals from particulate matter emissions

Exposure to air particulate matter (PM) is linked to numerous health effects. In order to improve the understanding of the role of its metallic components, their solubility was examined by using serial short-contact dissolutions totalling 1?h and additional sequential contact periods of 1, 4, and 8 days. The dissolution experiments were performed in solutions containing the main biological electrolytes. ICPMS determinations were used to quantify the dissolved metals. The total compositions were determined after closed vessel microwave digestion. Large variations in the rate and completeness of the dissolutions were observed. Fast and extensive dissolutions within the short-contact time (e.g., Zn, Cd) as well as slow dissolutions persisting during the last contact period (e.g., Ni, Cu, Sb, Pb) were found for smelting emissions. The multi-element determinations also made it possible to identify relationships between dissolution of different metals and define gradual composition changes of residual PM. When comparing with dissolutions performed in de-ionized water, similar major fractions were observed at short-contact time for minor components of smelting or combustion emissions (e.g., V, Ni, Cd), suggesting a preponderance of easily available forms at the surface of the relatively inert particle cores. The use of these time sequential methods may help in (1) modeling metal partitioning in biological media and (2) investigating the causes of adverse effects attributed to air PM.     

Characterization, dissolution and solubility of synthetic svabite [Ca5(AsO4)3F] at 25�C45��C

Svabite is a secondary arsenate mineral, calcium fluoride arsenate [Ca₅(AsO₄)₃F], in the apatite group of phosphates. Its dissolution and subsequent release of aqueous species play an important role in the cycling of arsenic and fluoride in the environment, but the thermodynamic and kinetic properties of svabite dissolution have never been investigated. In the present study, svabite was prepared by precipitation and characterized by various techniques, and then dissolution of synthetic svabite was studied at 25, 35 and 45°C in a series of batch experiments. In addition, the aqueous concentrations from the batch dissolution were used to calculate the solubility product and free energy of formation of svabite. The results of the X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy analyses indicated that the synthetic, microcrystalline svabite with apatite structure used in the experiments has not changed after dissolution. For the dissolution of svabite [Ca₅(AsO₄)₃F] in ultrapure water, F⁻ ions were initially found to dissolve preferentially when compared with calcium and arsenate. Preferential dissolution of arsenate when compared with that of calcium was also observed. Dissolution of svabite in aqueous medium appeared to be always non-stoichiometric at the beginning, but when a dissolution equilibrium or steady state was reached at 25 and 35°C, the solid dissolved almost stoichiometrically. The release of calcium, arsenic and fluoride to solution increased with decreasing temperature. The mean K _sp value was calculated for Ca₅(AsO₄)₃F of 10^−39.21 (10^−39.18 ~ 10^−39.24) at 25°C; the free energy of formation ΔG _f ^o [Ca₅(AsO₄)₃F] was −5210.46 kJ/mol.     

松毛虫遗传多样性研究中AFLP反应体系的建立

以油松毛虫为材料,对T4 DNA连接酶不同用量、预扩增中的Mg~(2+)浓度、dNTP浓度、引物浓度以及选择性扩增巾的预扩增产物稀释倍数、Mg2~(2+) 浓度、dNTP浓度、引物浓度和Taq酶浓度进行了比较分析.最终建立了适合松毛虫的AFLP反应体系.用优化的AFLP反应体系,以油松毛虫、赤松毛虫和马尾松毛虫为材料筛选引物,从81对引物组合中筛选出10对多态性高的引物组合.图9参17     

Maintenance of coelomic fluid pH in sea urchins exposed to elevated CO2: the role of body cavity epithelia and stereom dissolution

Experimental ocean acidification leads to a shift in resource allocation and to an increased [HCO₃ ^?] within the perivisceral coelomic fluid (PCF) in the Baltic green sea urchin Strongylocentrotus droebachiensis. We investigated putative mechanisms of this pH compensation reaction by evaluating epithelial barrier function and the magnitude of skeleton (stereom) dissolution. In addition, we measured ossicle growth and skeletal stability. Ussing chamber measurements revealed that the intestine formed a barrier for HCO₃ ^? and was selective for cation diffusion. In contrast, the peritoneal epithelium was leaky and only formed a barrier for macromolecules. The ossicles of 6 week high CO₂-acclimatised sea urchins revealed minor carbonate dissolution, reduced growth but unchanged stability. On the other hand, spines dissolved more severely and were more fragile following acclimatisation to high CO₂. Our results indicate that epithelia lining the PCF space contribute to its acid–base regulation. The intestine prevents HCO₃ ^? diffusion and thus buffer leakage. In contrast, the leaky peritoneal epithelium allows buffer generation via carbonate dissolution from the surrounding skeletal ossicles. Long-term extracellular acid–base balance must be mediated by active processes, as sea urchins can maintain relatively high extracellular [HCO₃ ^?]. The intestinal epithelia are good candidate tissues for this active net import of HCO₃ ^? into the PCF. Spines appear to be more vulnerable to ocean acidification which might significantly impact resistance to predation pressure and thus influence fitness of this keystone species.     

Effect of aging time on the availability of freshly precipitated ferric hydroxide to coastal marine diatoms

Cell growth and iron uptake of the coastal marine diatoms Chaetoceros sociale and Thalassiosira weissflogii were studied in the presence of short-aged amorphous ferric hydroxide (am-Fe(III)) media. These were prepared by aging for 1 day, 3 days, and 3 weeks after adding a small amount of ferric iron acidic stock solution to autoclaved filtered seawater and were experimentally measured in culture experiments at 10°C for C. sociale and 20°C for T. weissflogii. The order of cell yields for both species was: 1-day aged am-Fe(III) >3-day aged am-Fe(III) >> 3-week aged am-Fe(III) media. The iron uptake rates by C. sociale during 0–1 day in 1 day and 3-day aged am-Fe(III) media were about two-thirds and one-fourths, respectively, lower than that in the direct Fe(III) input medium containing C. sociale into which an acidic Fe(III) stock solution was added directly. The longer aging time of am-Fe(III) in media results in reducing the supply of bioavailable iron in the media by the slower dissolution rate of am-Fe(III) with the longer aging time. These results suggest that the chemical and structural changes of freshly precipitated amorphous ferric hydroxide with short aging time affect their ability, such as iron solubility and dissolution rate to supply bioavailable iron for the phytoplankton growth. The chemical and structural conversion of solid iron phases with time is one of the most important processes in changing the supply of available iron to marine phytoplankton in estuarine and coastal waters and in iron fertilization experiments.     

土壤中金属的生物可给性及其动态变化的研究

土壤中金属的生物可给性常应用于人体健康风险评价，如能准确地判定土壤中金属在胃肠阶段不同时间的溶出动态，研究者就可以更好地分析其对人体的健康风险。本文采集5种不同地区的重金属污染的土壤，利用改进的PBET方法，分别在胃阶段的20、40、60、80 min以及小肠阶段的1、2、3、4、5 h时取样并分析，探究土壤中8种金属元素（As、Al、Cd、Cr、Fe、Mn、Ni、Pb）的生物可给性和溶出动态，探讨造成金属溶出动态变化的影响因素，对其溶出机理进行初步探究。研究结果表明，Fe、Al的生物可给性较低，并且在胃肠阶段差异较小。与胃阶段相比，土壤中Pb、Cd的生物可给性在小肠阶段明显降低，而As、Mn、Cr、Ni的生物可给性在小肠阶段均升高。升幅最大的两个元素是Ni、Cr，其小肠阶段的平均生物可给性分别升高61.4%、29.9%。在溶出量随时间变化方面，在胃阶段，假定1 h时溶出率为100%。20 min时，土壤中Fe、Ni的平均溶出率较低，分别为59.3%、56.8%，其他6种金属元素的平均溶出率在71.2%~79.5%。As、Cd、Pb的溶出速率是先快后慢，Cr和Ni的溶出速率是先慢后快，而Fe、Mn、Al的溶出速率基本保持不变。在小肠阶段，假定4 h时溶出率为100%。Al、As、Cd、Mn的溶出率基本不变。1 h时，土壤中Cr（土壤A除外）、Ni的平均溶出率最低，分别为31.5%、32.7%，而5 h时，Fe、Cr、Ni的溶出率还在升高。由此可见，土壤中不同金属元素的生物可给性以及溶出动态是有明显差异的。     

Potassium carbonate-based ternary transition temperature mixture (deep eutectic analogues) for CO2 absorption: Characterizations and DFT analysis

•Addition of hindered amine increased thermal stability and viscosity of TTTM. •Addition of hindered amine improved the CO₂ absorption performance of TTTM. •Good the CO₂ absorption of recycled solvents after two regenerations. •Important role of amine group in CO₂ absorption of TTTM confirmed by DFT analysis. Is it possible to improve CO₂ solubility in potassium carbonate (K₂CO₃)-based transition temperature mixtures (TTMs)? To assess this possibility, a ternary transition-temperature mixture (TTTM) was prepared by using a hindered amine, 2-amino-2-methyl-1,3-propanediol (AMPD). Fourier transform infrared spectroscopy (FT-IR) was employed to detect the functional groups including hydroxyl, amine, carbonate ion, and aliphatic functional groups in the prepared solvents. From thermogravimetric analysis (TGA), it was found that the addition of AMPD to the binary mixture can increase the thermal stability of TTTM. The viscosity findings showed that TTTM has a higher viscosity than TTM while their difference was decreased by increasing temperature. In addition, Eyring’s absolute rate theory was used to compute the activation parameters (ΔG*, ΔH*, and ΔS*). The CO₂ solubility in liquids was measured at a temperature of 303.15 K and pressures up to 1.8 MPa. The results disclosed that the CO₂ solubility of TTTM was improved by the addition of AMPD. At the pressure of about 1.8 MPa, the CO₂ mole fractions of TTM and TTTM were 0.1697 and 0.2022, respectively. To confirm the experimental data, density functional theory (DFT) was employed. From the DFT analysis, it was found that the TTTM+ CO₂ system has higher interaction energy (|ΔE |) than the TTM+ CO₂ system indicating the higher CO₂ affinity of the former system. This study might help scientists to better understand and to improve CO₂ solubility in these types of solvents by choosing a suitable amine as HBD and finding the best combination of HBA and HBD.