三峡库区重庆段几种土壤元素全量与其有效态含量的相关关系分析

利用重庆市沿江经济带地球化学调查所得土壤分析数据,研究了三峡库区重庆段土壤中元素的丰缺状况及其全量与有效态含量的相关关系。在进行相关关系分析时,主要考虑了不同土壤类型和土壤的pH值两个因素。结果表明,研究区B、Cu、Mn、Zn、K、Fe元素全量现状水平充足;N、P、Mo元素全量现状水平缺乏;有效态B、Mo、P、Zn含量缺乏;有效态Cu含量丰富;有效态Mn、N、Fe和速效K含量充足。元素有效态含量易受土壤类型和土壤的pH值影响,在很大程度上受土壤类型影响较大。在研究区的四类土壤类型中N、Mn元素全量与其有效态含量相关关系较好;P元素在石灰土和水稻土中其全量和有效态含量相关关系显著。     

Composition and variability of soil solutions as a measure of human impact on protected woodland areas

A study was made of the sandy and loamy soils of the woodland areas of the Wielkopolski National Park (Poland) affected by acid rain. The basic properties of the soils were determined, revealing their strong acidification, poor buffering power, and the possibility of aluminium release. An analysis was made of the content of soluble, exchangeable, organic, amorphous, and free forms of aluminium. The concentration of exchangeable aluminium exceeded that of the form dissolved in soil water several times to tens of times. In soil solutions Ca/Al ratios in some horizons show very low values that could induce a nutrient deficit. In the sandy profiles the ratio even drops below the critical level of 0.1. In the surface horizon the dominant cation at all the sites is the aluminium ion. An analysis of anions shows a dominance of sulphate and chloride ions. In autumn nitrites were recorded at all depth levels, while in spring only in the surface layers. The highest fluoride concentrations were found to occur in profiles situated the closest to the emission source of fluorine compounds. The markedly higher concentrations of ammonium than nitrate ions can lead to increased acidification and eutrophication of the soil.     

A Unified Approach to Phytosiderophore Natural Products

This work reports on the concise total synthesis of eight natural products of the mugineic acid and avenic acid families (phytosiderophores). An innovative „east-to-west“ assembly of the trimeric products resulted in a high degree of divergence enabling the formation of the final products in just 10 or 11 steps each with a minimum of overall synthetic effort. Chiral pool starting materials (l -malic acid, threonines) were employed for the outer building blocks while the middle building blocks were accessed by diastereo- and enantioselective methods. A highlight of this work consists in the straightforward preparation of epimeric hydroxyazetidine amino acids, useful building blocks on their own, enabling the first synthesis of 3’’-hydroxymugineic acid and 3’’-hydroxy-2’-deoxymugineic acid.     

Innovative Formulations of Phosphate Glasses as Controlled-Release Fertilizers to Improve Tomato Crop Growth,Yield and Fruit Quality

Three phosphate glass compositions, VF1, VF2, and VF3, containing macro and micronutrients with different [K₂O/(CaO+MgO)] ratio, were formulated to be used as controlled release fertilizers for tomato crop, depending on their chemical durability in water and their propriety with respect to the standards of controlled-release fertilizers. This study investigated the influence of [K₂O/(CaO+MgO)] ratio variation on glass properties. For this, the elaborated glasses have undergone a chemical characterization using inductively coupled plasma atomic emission spectroscopy, a thermal characterization using differential thermal analysis, a physicochemical characterization based on density and molar volume measurements, and a structural characterization using Raman spectroscopy, Fourier-transform infrared spectroscopy, and X-ray diffraction. In addition, the chemical durability was determined by measuring the percentage of weight loss and the pH. Results revealed that the glass structure and composition have the mean role in controlling the release of nutrients in water. By increasing [K₂O/(CaO+MgO)] ratio, the dissolution rates of the glasses increased due to the shrinking in the rate of crosslinking between phosphate chains, accompanied with a diminution in transition and crystallization temperatures, and an increase in the molar volume. An agronomic valorization of VF1 and VF2 glass fertilizers, which showed dissolution profiles adequate to the criteria of controlled-release fertilizers, was carried out to evaluate their efficiency on tomato crops. These glass fertilizers improved soil mineral content and tomato performances in comparison to the control and NPK treatments with the distinction of VF2. The results highlight the effectiveness of these smart fertilizers toward their potential large-scale application to improve crop production and quality for high nutritional value foods.     

电感耦合等离子体质谱(ICP-MS)法测定土壤中的有效钼

准确快速测定土壤中的有效钼,是评价土壤肥力的重要指标,对指导作物生产有重大意义。本文采用草酸-草酸铵溶液浸提土壤样品,待测浸提液稀释5倍后通过电感耦合等离子体质谱法在氦气模式下测定土壤中有效钼的含量,建立了土壤中有效钼高灵敏度分析的检测方法。选择103Rh为内标元素,校正仪器在测定过程中引起的信号飘移。对两种前处理方式进行比较,确定了震荡30 min、放置过夜的浸提方法浸提效果更好且更利于大批量样品的分析。使用震荡30 min、放置过夜的浸提方法对5个土壤标准物质有效钼进行前处理,其测定值均在标准值范围内;分别在无气体模式和氦气模式下比较了浓度为0mg/L、1mg/L、2mg/L、5mg/L、10mg/L、50mg/L的Mn对5ug/L 95Mo测定浓度的影响,结果表明氦气模式下的动能歧视可有效去除95Mo测定过程中的多原子离子的干扰,氦气模式测定有效钼明显优于无气体模式;分别对待测溶液稀释5倍和未稀释的内标回收率趋势进行监测,发现未稀释的样品内标回收率随着测量样品数的增多呈下降趋势,而稀释5倍对基体干扰的消除有显著效果。对5个土壤样品分别重复测定6次,其RSD均小于4.1%;线性相关系数为1.0000;方法检出限为0.0012 mg/kg。综上,该方法测定土壤有效钼结果准确,重现性好,灵敏度高,且适合大批量样品的分析。     

微流池多光程土壤有效态氮磷测定方法研究

农业面源氮磷污染是当前地表水体污染主要来源,而土壤有效态氮磷测试大都依赖于流动分析仪在实验室完成,无法满足个性化土壤有效态氮磷现场测定需求。建立了一种微流池多光程的土壤有效态氮磷测定技术,通过柔性化参数设置,实现不同土壤有效态氮磷测试规范和现场测试。以广东省韶关市农业科学研究所和北京市农林科学院提供的26个样品为例进行有效态铵态氮、硝态氮和磷测定验证。实验结果表明,微流池多光程土壤有效态氮磷测定方法中有效态铵态氮、硝态氮和磷的检出限(LOD)分别为0.0086、0.0094和0.0078 mg/L,相对标准偏差(RSD)分别为0.80%、5.7%和0.90%,加标回收率在92.0%~103%,平均单样品测试时间6 min。测试过程自动化,极大地提升了土壤有效态氮磷测定效率和测试结果准确性,为农业面源污染防治提供技术支撑。     

High-temperature (GC)2/MS investigations

The analysis of low volatile compounds by (GC)²/MS using high-temperature stable glass-capillary columns and a commercially available GC/quadrupole MS instrument is described. It will be shown that no special modifications or procedures are required in analyzing organic compounds exceeding carbon numbers of 50. The application to industrially and naturally occuring high boiling mixtures will be discussed.     

Emission phenomena in electrochemical systems: Investigation of solvated and delocalized electrons in polar media

The principles of using the results of studies of emission phenomena in electrochemical systems for determination of the energy levels of excess (solvated and delocalized) electrons in electrolyte solutions are formulated. The energy characteristics of excess electrons in hexamethylphosphoric triamide have been estimated on the basis of data obtained by the author and literature data (results of photo- and thermoelectron emission measurements and equilibria studies in solutions of solvated electrons). The energy levels of solvated electron and bi-electron, their photoionization energies and solvent reorganization energies have been found. The nature of the absorption spectra is discussed.     

环境样品中生物可利用态镉的反相离子对-HPLC-荧光检测

镉是一种有毒的重金属元素 ,是生态环境中最常见和最主要的污染元素之一 [1] .目前 ,用于镉的测定方法主要有原子吸收法 [2 ]、ICP- MS法 [3]和荧光分光光度法 [4 ] ,但这些方法由于灵敏度或者选择性的限制以及来自基体的严重干扰等问题 ,常常在实际样品测定中遇到困难 .高效液相色谱及其联用技术的发展使复杂样品中痕量元素的测定得以实现 [5～ 7] .本文将长链的阳离子表面活性剂十六烷基三甲基溴化铵 ( HTMAB)作为离子对试剂 ,8-羟基喹啉 - 5 -磺酸 ( HQS)作为在线配位及荧光衍生试剂 ,建立了镉的离子对色谱检测方法 ,并应用于土壤…     

污泥的异重流化床燃烧机理研究

采用异重流化床燃烧技术 ,在一内径为Φ60mm的小型热态流化床上进行了污泥的凝聚结团特性及燃烧特性试验 ,得到了污泥在异重流化床炉内的水分蒸发及挥发分析出过程。对不同污泥燃烧过程的可用能进行分析。选取了宁波污泥在TGD - 50 0RH差示热天平上进行了热重法 (TG) ,微商热重法 (DTG) ,热差分析 (DTA)等分析 ,得出污泥的差热曲线 ,归纳出污泥的动力学参数和方程。