土壤中砷吸附机理及其影响因素研究进展

土壤中砷(As)的生物可利用性、迁移、转化及归宿在很大程度上依赖于其在土壤中的吸附反应.本文首先概述了土壤中As污染物的主要形态、价态及其与吸附的关系,较为系统地介绍了土壤中As吸附的主要影响因素和土壤中As吸附机理等方面的最新研究进展,并重点对X-射线吸收精细结构光谱(XAFS)、红外光谱(IR)等现代分析技术和方法在As吸附研究中的应用和进展进行了论述.由于土壤组分与结构的复杂性,As在环境介质中的吸附机理研究目前仍集中在单纯矿物上的吸附行为,为As在土壤中的吸附研究提供了理论基础.X-射线吸收精细结构光谱及红外光谱研究结果证明As在土壤中的吸附主要与含Fe、Al等矿物结合,形成以双齿双核结构为主的配位结构;其吸附机理与土壤矿物及As污染物的价态、吸附浓度等有关,主要包括表面络合反应和表面沉淀作用:但是土壤中As吸附机理研究还需要进一步深入研究.文章最后分析了有关土壤中As吸附研究的发展趋势和重要动向.     

土体元素活化发展方向初探

土体中氮、磷、钾等营养元素的寄存量大,植物无法直接吸收利用。为了减少肥料施入,活化土壤中惰性态营养元素,研究新的元素活化方法十分必要。目前,光能、太阳能、超声波以及生物质能够在一定程度上活化土壤元素,但对活化机理以及活化技术研究并不深入,因此提出从元素活化机理、能态对元素的活化影响以及元素活化的装备研发与技术集成这三方面探索土体元素活化未来的发展。     

保存过程对土壤生化指标的影响及保存土样的应用

土壤样品的生化指标反映了样品采集时期的生态与环境信息,具有极为重要的科学研究价值。样品的生化指标在保存过程中是否发生变化,是保存样品应用中应关注的重点问题。本文总结了各类土壤生化指标在不同保存条件、保存时间下的变化,表明长期保存的土壤样品适用于全量元素含量测定、土壤微生物群落结构分析、DNA/RNA序列分析、土壤污染物分析和土壤酶活性的比较研究,而土壤速效成分以及呼吸、硝化等代谢过程相关指标则不宜采用保存土样。土样长期保存应采用风干、磨口玻璃瓶密封、常温保存的方式。保存土样应用过程中应注意避免取样、分析时的环境污染,采用合适的分析测试技术,并考虑不同类型土壤保存效应的差异。随着分析技术的发展,保存土样中更多的历史环境信息将得以发掘,发挥出更大的科研价值。     

应用氢氧同位素技术研究土壤水的原理与方法

土壤水是联系地表水、地下水和生物地球循环的纽带,在水资源的形成、转化及消耗过程中有重要作用,与农业、水文、环境等领域都有密切关系。氢氧同位素技术利用了自然水体中氢氧同位素组成来标记水循环过程,可以更加灵敏和准确地揭示许多其他技术很难获取的水文过程信息如入渗、蒸发、蒸散和渗透等,从而为进一步研究土壤水分的垂直迁移、滞留时间以及植物对土壤水的吸收利用机理等提供了重要依据。因此,土壤水中稳定同位素可以作为一种天然的示踪剂来追踪降水-土壤水-地下水之间的转化乃至土壤-植物-大气界面的输送和循环过程。     

同步辐射XAFS技术在元素研究中的应用

综述了同步辐射XAFS的基本原理和优点及其在若干研究领域元素测定中的应用。     

激光诱导击穿原子光谱在土壤分析中的应用

土壤分析是土壤学研究及应用的前提和基础,传统化学土壤分析方法逐渐不能适应现代土壤学海量信息数据快速获取的需求。激光诱导击穿光谱作为一种全新的、反映土壤组成元素原子信息的光谱技术,其无需对样品进行复杂前处理,可实现原位、快速、多元素连续在线检测,每条光谱记录土壤样本独一无二的特征,可以视为土壤“指纹”,成为现代土壤分析的有效技术之一。首先介绍和分析了激光诱导击穿原子光谱的原理、光谱获取的主要影响因素、光谱数据处理的化学计量学方法等;然后阐述和梳理了基于激光诱导击穿光谱技术在土壤分析方面的应用成果和进展,包括土壤鉴定、土壤养分评估、土壤重金属测定、微观/介观尺度土壤原位表征等;最后讨论和总结了激光诱导击穿光谱技术在土壤分析中所面临的挑战及其应用展望。     

同步辐射X射线吸收精细结构(XArS)技术在元素研究中的应用

综述了同步辐射XAFS的基本原理和优点及其在若干研究领域元素测定中的应用.     

高光谱在土壤重金属信息提取中的应用与实现

以建设一套基于光谱数据的土壤重金属信息提取系统为研究目标,总结了土壤重金属指标及其光谱学机理。在软件技术和数据库技术支持下,实现了土壤重金属光谱信息管理、处理、分析和应用。研究表明:土壤重金属元素在其特征波段上所显示的光谱特性,经过光谱预处理、变换和定量化提取,能够为建模提供理论依据。在计算光谱统计特征量基础上,采用光谱分析法,自动检索土壤重金属光谱特征位置。以东北黑土地机载高光谱CASI和SASI数据为例,计算了硒、锰和铁等元素的含量,最高硒元素含量达到了80.767 mg kg~(-1)。随着植被覆盖率的提升,硒、锰、锡和锌元素的含量随之升高,说明水稻吸收了部分金属元素,对特征波段反射率产生了影响。     

某放射性污染区盐生植物对~(137)Cs的吸收研究

植物修复技术适用于大面积、低活度的放射性污染治理,在一些大面积放射性污染区具有潜在的应用前景。本研究在某放射性典型污染区域取样,测量了该区域盐生植物及其生长土壤的137Cs含量,以生物富集系数(BC值)为指标,分析了不同核素土壤分布、K元素含量等因素对BC值的影响。研究结果表明,污染区植物对137Cs的吸收BC值在10-5~10-2数量级之间,多数区域由于核素分布不均匀而引起BC值下降,均匀分布则有利于核素的吸收。另外,BC值还与土壤K元素含量呈负相关。     

土壤空间变异研究进展

本文主要综述了土壤空间变异研究的进展,包括土壤水分特征及状态参数、物理性质、化学性质、重金属及其它元素的空间变异研究。讨论了尺度效应及套合结构模型在空间变异研究中的应用和研究进展,指出应根据不同研究目的采用不同的研究方法,并确定恰当的研究尺度,分析统计结果应结合区域生态系统进行分析。     

Neighbors' Perceptions of Mushroom Farms At the Rural/Urban Interface

Changes at the rural/urban interface are presenting new challenges for many mushroom farms, who increasingly find themselves the subject of public complaints from nonfarming neighbors. Identifying the type and extent of neighbors concerns is important for farmers and local officials to respond appropriately. This study examined neighbors' perceptions of mushroom farms in Chester County, Pennsylvania, the nation's most productive mushroom producing area. Telephone interviews with 601 neighbors found about 23 percent of neighbors reported having a concern. Odors were the most common concern, held by 14 percent of respondents (and being 36 percent of all concerns). Neighbors were less likely to have concerns if they were aware of the mushroom farm before moving to the area, and more likely to have a concern if the farm changed operation after they moved. (Ed. Note: Data provided in this analysis of neighbors' attitudes are valuable to operators of composting facilities.)     

凝胶型保水缓释氮肥形貌结构及盐分的影响

采用环境扫描电镜和红外光谱观察和解析凝胶型保水缓释氮肥的形貌及物理结构和化学特征。结果表明,保水缓释氮肥干样品相结构是一个整体不均匀而局部较均匀的凝胶。保水缓释氮肥凝胶吸水膨胀体为透明的水凝胶,具有网络结构和孔隙,这是其存贮水分的物理空间。盐分影响或破坏保水缓释氮肥的物理和化学结构,破坏程度为氯化钠小于氯化钙,氯化钙对保水缓释氮肥网络物理结构的破坏用蒸馏水洗涤几乎不可逆转。因此,提高保水缓释氮肥的耐盐性是提高保水缓释氮肥吸水倍率的重要因素。     

基于可视化类库的植株三维形态配准方法及点云可视化

精确的植物三维静态形态结构模型有助于植物空间结构相关的各种研究,是虚拟植物、植物建模等问题研究的一个重要方面。研究植物生长过程中的三维信息的获取可以获得作物生长过程中各参数的动态数据,可为精细农业植物生长模型建立等提供依据。该文以植物为研究对象,介绍了虚拟植物及植物三维可视化的研究现状,讨论了植物叶片三维可视化的可行性及必要性。针对植物三维点云的采集与处理上,讨论了三维扫描仪的精度测定方法,并针对基于基准体的植株点云配准问题,提出采用基准体点云平均法向量计算的方法,去除了部分基准体表面的噪声点,提高了植株体的配准精度;采用迭代最近点（iterative closest point,ICP）算法,对植株叶片进行进一步的高精度配准。最后采用基于可视化类库VTK(visualization toolkit)实现了植物点云配准与三维可视化。     

利用X射线CT研究多尺度土壤结构

土壤结构影响着土壤中的各种物理、化学和生物学过程。近年来,X-射线CT已经发展为研究土壤结构的主要手段。本文首先介绍X射线CT的基本原理,然后总结了主要的CT类型及其在土壤结构研究中的应用。在此基础上,举例介绍了医用CT、工业显微CT和同步辐射显微CT在大土柱（直径100 mm,高200 mm）、小土柱（直径30 mm,高30 mm）和团聚体（直径5 mm）结构研究中的应用,利用CT图像的处理和分析方法,分析了不同大小样品的孔隙分布特征,讨论了综合利用不同类型CT研究不同尺度土壤结构的方法。     

Technological classification of basque cider apple cultivars according to their polyphenolic profiles by pattern recognition analysis

The polyphenolic compositions of 31 Basque cider apple cultivars were determined in pulp, peel, and juice by high-performance liquid chromatography--diode array detection analysis of crude extracts and after thiolysis. Data sets, consisting of individual polyphenol concentrations, total procyanidin content, and the average degree of polymerization of procyanidins, were evaluated by multivariate chemometric techniques, to develop decision rules for classifying apple cultivars technologically into bitter and nonbitter categories. A preliminary study of the data structure was performed by cluster analysis and principal component analysis in each apple material. Bitter apple varieties presented higher contents of flavan-3-ols and/or dihydrochalcones than nonbitter cultivars. Different classification systems for the two categories on the basis of the chemical data were obtained applying several supervised pattern recognition procedures, such as linear discriminant analysis, K-nearest neighbors, soft independent modeling of class analogy, partial least-squares, and multilayer feed forward artificial neural networks. Excellent performance in terms of recognition and prediction abilities for both categories (100% of hits) was achieved in every case (pulp, peel, or juice). Polyphenolic profiles of apple pulp, peel, or juice provide enough information to develop classification criteria for establishing the technological group of apple cultivars (bitter or nonbitter).     

Public health concerns for neighbors of large-scale swine production operations

This article provides a review and critical synthesis of research related to public health concerns for neighbors exposed to emissions from large-scale swine production operations. The rapid industrialization of pork production in the 1990s produced a generation of confined animal feeding operations (CAFOs) of a size previously unseen in the U.S. Recent research and results from federally sponsored scientific symposia consistently indicate that neighbors of large-scale swine CAFOs can experience health problems at significantly higher rates than controlled comparison populations. Symptoms experienced by swine CAFO neighbors are generally oriented toward irritation of the respiratory tract and are consistent with the types of symptoms among interior confinement workers thathave been well documented in the occupational health literature. However, additional exposure assessment research is required to elucidate the relationship of reported symptoms among swine CAFO neighbors and CAFO emissions.     

Shining light on the differences in molecular structural chemical makeup and the cause of distinct degradation behavior between malting- and feed-type barley using synchrotron FTIR microspectroscopy: a novel approach

The objective of this study was to use advanced synchrotron-sourced FTIR microspectroscopy (SFTIRM) as a novel approach to identify the differences in protein and carbohydrate molecular structure (chemical makeup) between these two varieties of barley and illustrate the exact causes for their significantly different degradation kinetics. Items assessed included (1) molecular structural differences in protein amide I to amide II intensities and their ratio within cellular dimensions, (2) molecular structural differences in protein secondary structure profile and their ratios, and (3) molecular structural differences in carbohydrate component peak profile. Our hypothesis was that molecular structure (chemical makeup) affects barley quality, fermentation, and degradation behavior in both humans and animals. Using SFTIRM, the protein and carbohydrate molecular structural chemical makeup of barley was revealed and identified. The protein molecular structural chemical makeup differed significantly between the two varieties of barleys. No difference in carbohydrate molecular structural chemical makeup was detected. Harrington was lower than Valier in protein amide I, amide II, and protein amide I to amide II ratio, while Harrington was relatively higher in model-fitted protein alpha-helix and beta-sheet, but lower in the others (beta-turn and random coil). These results indicated that it is the molecular structure of protein (chemical makeup) that may play a major role in the different degradation kinetics between the two varieties of barleys (not the molecular structure of carbohydrate). It is believed that use of the advanced synchrotron technology will make a significant step and an important contribution to research in examining the molecular structure (chemical makeup) of plant, feed, and seeds.     

Glomalin-related soil protein contains non-mycorrhizal-related heat-stable proteins, lipids and humic materials

Glomalin is reportedly a stable and persistent protein produced in copious quantities by mycorrhizal fungi and may be an important pool of organic N in soil. Glomalin-related soil protein (GRSP), however, is only operationally defined by its extraction method, and has been only poorly characterized at best. The goal of this study was to characterize the molecular structures within GRSP. Synchrotron-based X-ray absorption near-edge structure (XANES) spectroscopy and pyrolysis field-ionization mass spectrometry (Py-FIMS) revealed that GRSP contains a consortium of proteins along with many impurities. Employing proteomic techniques, we found that glomalin itself may be a thioredoxin-containing chaperone; however, no homologies with proteins or DNA of mycorrhizal origin were detected. Proteomics techniques further revealed that this fraction contains large amounts of soil-related heat-stable proteins and proteins of non-mycorrhizal origin. Results of this research show that the current extraction procedure that defines GRSP yields a mixture of compounds and thereby overestimates glomalin stocks when quantified using the Bradford assay. The chemical nature of glomalin has yet to be conclusively determined; it is unlikely that the chemical structure of glomalin can be elucidated from the mixture extracted as GRSP. Instead, an investigation into the specific biochemistry of immunoreactive assays currently used to define GRSP, followed by proteomic characterization of monoxenic mycorrhizal cultures may be required to advance our understanding of the chemical nature and agronomic significance of GRSP in soils.     

海岸带土地利用模拟结果对元胞邻域的响应研究

通过元胞自动机（Cellular Automata,CA）动态模拟能够重建和预测复杂系统的全局结构及其演变。海岸带土地利用变化模拟是CA应用研究的重要领域之一。元胞邻域及其组合作为CA的必要组成部分,对海岸带模拟结果有显著影响。以半径为1,2和3的Moore邻域为例,测试并分析了模拟结果对元胞邻域的响应。研究表明:这种影响表现在3个方面:分别是元胞数量、空间形态和不确定性。小范围邻域组合模拟结果形态真实、不确定性较低,但是模拟变化容易过早终止;大范围邻域组合模拟结果形态真实性较差、不确定性较高,但是模拟结果能够保持延续。针对具体的模拟案例,元胞邻域的选择需要结合影响系统演变的全局因素而确定。模拟结果的响应特征不仅适合海岸带土地利用模拟,也适合其他类型的空间系统演变模拟。     

应用~(13)C核磁共振技术研究土壤有机质化学结构进展

土壤有机质化学结构对准确评价土壤有机质的稳定性及其在土壤中的功能具有重要意义。土壤有机质化学结构的研究方法中,固态~(13)C核磁共振波谱技术(Solid-state ~(13)C-NMR spectroscopy)具有独特优势,对土壤有机质化学结构的解析更贴近真实状态,近年来已取得诸多新进展和新突破。综述了近年来应用~(13)C-NMR测定土壤全土、团聚体和密度组分、腐殖质组分的有机碳化学结构特征,分析了影响化学结构变化的因素。不同气候条件、植被类型、土地利用管理方式、土壤类型、土壤有机碳含量的全土中有机碳化学结构比较相似,均表现为烷氧碳比例最高,其次为烷基碳和芳香碳,羧基羰基碳比例最低。土壤有机碳主要来源于外源植物残体,植物残体化学结构的相似性可能是导致土壤有机碳化学结构相似的主要原因,环境条件、土壤自身属性和微生物活性的差异使土壤有机碳化学结构产生微小差异。土壤颗粒及化学组分间的有机碳分子结构差异较大,大颗粒有机碳中烷氧碳比例最高,小粒径及与矿物颗粒结合的有机碳中烷基碳和羧基羰基碳比例更高,粉黏粒和腐殖酸组分的有机碳化学结构在土壤类型间差异较大。今后的研究重点应更多地关注土壤有机质来源的定量化分析、土壤微生物对土壤有机碳组分和结构稳定性的贡献及调控机制、土壤有机碳稳定性的生物物理化学保护机制、空间大尺度环境因子/土壤生态过程与微观尺度的有机碳化学分子结构的耦合作用机制、跨学科的多种土壤有机碳化学分子结构测定辨识技术等方面的研究。