Chemical modification of pyroclastic rock by hot water: an experimental investigation of mass transport at the fluid–solid interface

Hydrothermal water–(pyroclastic) rock interactions were examined using flow-through experiments to deduce the effect of mass transport phenomena on the reaction process. A series of experiments were conducted over the temperature range 75–250°C, with a constant temperature for each experiment, and at saturated vapour pressure, to estimate the apparent rate constants as a function of temperature.
Based on the chemistry of analysed solutions, the water–rock interaction in the experiments was controlled by diffusion from the reaction surface and by the existence of a surface layer at the rock–fluid interface, which regulated the chemical reaction rate. The reaction progress depended to a high degree on flow velocity and temperature conditions, with element abundances in the fluid significantly affected by these factors. Mass transport coefficients for diffusion from the rock surface to the bulk solution have been estimated. Ca is selectively depleted under lower temperature conditions ( T  < 150°C), whereas Na is greatly depleted under higher temperature conditions ( T  > 150°C), and K reaction rates are increased when flow velocity increases. Using these conditions, specific alkali and alkali earth cations were selectively leached from mineral surfaces. The 'surface layer' comprised a 0.5–1.8 mm boundary film on the solution side (the thickness of this layer has no dependence on chemical character) and a reaction layer. The reaction layer was composed of a Si, Al-rich cation-leached layer, whose thickness was dependent on temperature, flow velocity and reaction length. The reaction layer varied in thickness from about 10⁻⁴ to 10⁻⁷ mm under high temperature/low fluid velocity and low temperature/high fluid velocity conditions, respectively.     

An experimental and modeling study of Na-rich hydrothermal alteration

Sodic alteration assemblages including clinoptilolite, mordenite, analcime and Na‐montmorillonite were locally observed in sediments in the eastern part of the Hachimantai geothermal region, northeast Japan. This study investigated the mechanisms of sodic enrichment in the sediments during alteration. Kinetic results for water/rock interaction experiments are reported here. Batch‐type experiments were conducted at 150–250°C under saturated vapor pressure. Pyroclastic rocks dissolved incongruently in these experiments, and the solubility and dissolution rates among elements varied as follows: the apparent steady‐state concentrations of major elements are Si > Na ? K > Ca > Al and the order of the dissolution rates is Si > Al > Na ? K > Ca. Na had the highest steady‐state concentration and fastest dissolution rate of the alkali and alkali earth metal ions. Based on surface analysis of plagioclase, dissolution was effected via a reaction layer of Na‐montmorillonite on the mineral surface. Additionally, a reaction model constructed based on the experimentally observed reaction mechanism quantitatively explains the dissolution behavior. These results show that Na‐montmorillonite can be precipitated by pyroclastic rock/meteoric water interactions without seawater involvement: the Na is derived from the host rocks.     

青铜器锈蚀结构组成及形态的比较研究

采用X射线衍射(XRD)、扫描电镜(SEM)、X射线电子能谱(EDS)和金相显微镜(OM)等方法,分析比较了染有“粉状锈”与未染“粉状锈”的典型青铜残片的锈蚀产物的矿物组成、腐蚀层分层结构及金相组织。结果发现,未染有“粉状锈”的青铜样品腐蚀层一般分为二层,外层是二价铜化合物,合金组织中未见α (α δ)组织,锈蚀产物中不含碱式氯化铜;而染有“粉状锈”的青铜样品都含有碱式氯化铜,其断面腐蚀层分三至四层,且每层锈体的结构和元素组成各不相同,在靠近合金基体层的锈层中发现了大量的CuCl存在。结果表明,青铜文物表面锈蚀覆盖层的致密性、空气中的湿度及锈层中CuCl层状分布的存在,是青铜器表面“粉状锈”形成和发展的根本原因。     

中国北方干燥地区出土糟朽漆器加固材料及修复方法

为探索一种适合于我国北方干燥地区出土糟朽漆器保护的材料和方法,从而解决这类漆器的保护问题。通过试验比较,以水、乙醇和丙三醇作为中国古代北方干燥地区出土漆器漆皮的回软修复材料;选用乳液型粘合剂与纸、绢、古代木材作为回软漆皮的加固材料;选用聚乙二醇乙醇溶液与Paraloid B72丙酮溶液为渗透加固剂,对三件糟朽漆器加固取得很好的效果。实验表明,本方法为中国北方干燥地区出土糟朽漆器的保护修复,提供了一种科学易行的方法和材料。     

基于旅游行为的旅游目的地空间层次与管理

关于旅游目的地的空间研究比较丰富,视点主要在于经济与地理空间。但是,旅游业是市场导向非常明显的行业,从旅游行为角度研究旅游目的地的空间层次更具有现实意义,对指导旅游目的地的开发和管理更具有操作性。本论文从旅游行为导向、管理方便性角度,融入社区理念,提出了新的旅游目的地解读,将其划分为三个空间层次,即游览服务区、社区服务区和社会服务区,并分析了它的空间层次结构关系和主要要素。论文最后从规范管理角度提出管理层次与关系。     

史前漆膜的分析鉴定技术研究

研究了漆膜分析的三种主要方法：裂解质谱,红外光谱,裂解色谱。通过大量实验比较了各种方法的适应性和可靠性,建立了以裂解色谱／富里叶红外光谱联用技术来鉴定漆膜,并对影响裂解反应的因素及色借条件进行了深入的研究,获得了可以重复,具有特征性的漆膜高分辨裂解色谱图,同时对裂解色谱图中主要组分作了定性鉴定,提高了裂解色谱法分析漆膜的可靠性。该方法具有灵敏度高,样品用量小,共存杂质影响小,操作简便等优点。应用核分析技术对河姆渡,良诸庙前遗址出土的二件红色涂料样品进行了鉴定。分析结果证实了河姆渡出土的红色涂料木碗上的涂料是我国至今发现的最早的生漆漆膜。     

Degradation processes in colourless Roman glass: cases from the Bocholtz burial

A group of Roman glass objects from the Bocholtz burial in the SW of Limburg (The Netherlands) was found to have been subject to varying degrees of degradation. Many of the 25 colourless glass objects were fragmented to pieces <0.1 cm (“sugared”), whereas the three transparent blue-green glass objects were in near-pristine state. Analyses using SEM, XRF and EDS revealed that the fragmentation was the direct result of the intense leaching of Na₂O from the glass structure and its replacement with water. The resulting gel layers with low-Na₂O contents and large amounts of water are sensitive to cracking when they dry out. Thin-walled glass appears to be less sensitive to cracking from the resulting stress than thick-walled glass. Local differences in the moisture regime during burial also influence the severity of the glass degradation. Glass with low concentrations of CaO seems to be the most sensitive to this form of degradation. The typical blue-green Roman glass is less sensitive as it generally has considerably higher concentrations of CaO.     

康熙朝雕漆初探

康熙朝有无雕漆,一直悬而未决。本文通过对故宫博物院所藏7件雕漆作品的造型、漆色、雕工、装饰纹样、款识等多方面的分析,认为康熙朝有雕漆,并推断为苏州制造。     

清雕漆描金宝座材料与工艺研究

为了了解清雕漆描金宝座的材料和工艺,对胎体制作切片进行了显微镜观察,确定了其种属;采用傅里叶红外光谱分析法分析了红漆,图谱与桐油很相近,由此可确定调漆工艺中加入了桐油。另外,结合文献,初步复原了此宝座的髹漆工艺。此研究对宝座以后的保护及清代家具及漆器的制作工艺具有参考价值。     

秦俑陶质彩绘原始工艺和剥落过程的探索性研究

为了制作陶俑彩绘的仿真样品,探索失传两千年的秦人制作陶质彩绘的原始工艺,根据已知的各种信息,探讨了秦俑彩绘制作的传统工艺,包括生漆添加猪血的作用、生漆层的配方、颜料层的配方、生漆层和颜料层的制作方法、基底陶块的选择等。制作了陶俑彩绘的仿真样品:生漆层厚度为35~68μm;颜料层厚度:红色20~50μm,白色55~70μm、绿色50~70μm、蓝色55~65μm,与秦俑生漆层和彩绘层的真实厚度相近。生漆层中猪血的最适应比例为4%,颜料层中所用粘合剂适宜浓度:明胶:水为1:32,蛋清:水为1:2。仿真样品经过加速老化破坏循环后,可以大体重现彩绘从陶块上起翘脱落的过程。研究结果为进一步研究病害机理,开展彩绘加固或回贴实验等研究提供了基础方法。