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土遗址和壁画遗址可溶盐主要为NaCl和Na_2SO_4,其中Na_2SO_4是破坏程度最严重的盐。一般认为,硫酸钠只有在温度、湿度变化时才不稳定,才发生得失结晶水引起的晶型及体积变化。为研究土质文物盐害的形成机制及内在原因,调研了全国几处典型土遗址和壁画遗址的盐害状况并取样分析。分析发现:1)土遗址和壁画遗址中硫酸钠的形貌、结构是动态变化的(无论在任何极端干燥环境甚至真空条件下);2)环境因素如温度、相对湿度的变化只是加剧上述变化进程。硫酸钠结晶析出时,其体积膨胀约4倍。这一系列的过程,深刻影响着硫酸钠的相变复杂性和对依存土质文物本体的破坏性。本工作从微观和宏观两个层面探讨了这些发现,并通过不同盐分(不同浓度氯化钠、硫酸钠)侵蚀破坏模拟试验、不同温度条件下模拟试验、不同相对湿度下模拟试验,从宏观层面印证了上述微观机制在土遗址和壁画遗址本体的外在表现。本研究发现土遗址中硫酸钠的形貌、结构是动态变化的,该工作弥补了以往研究和认识上的局限。本研究将对阻止、延缓及预测土质文物盐害的发生、发展提供科学参考。
The soluble salts of earth and mural sites are mainly NaCl and Na_2SO_4, among which Na_2SO_4 is the most destructive salt. It is generally believed that sodium sulfate is unstable only when the temperature and humidity are changed, and changes in crystal form and volume caused by the loss of water of crystallization occur. In order to study the formation mechanism and the internal causes of salt damage of soil relics, the salt damage status of several typical soil sites and mural sites in China was investigated and sampled. The analysis shows that: 1) The morphology and structure of sodium sulfate in soil sites and mural sites are dynamic (no matter in any extreme dry or even vacuum conditions); 2) The change of environmental factors such as temperature and relative humidity only aggravate the above changes process. When sodium sulfate crystallizes out, its volume expands about 4 times. This series of processes has a profound impact on the complexity of the phase transition of sodium sulfate and its destructiveness to the ontology of dependent soil relics. This work explores these findings from the micro and macro levels, and through different salt (different concentrations of sodium chloride, sodium sulfate) erosion damage simulation test, different temperature conditions simulation test, different relative humidity simulation test, from the macro level Which confirms the external manifestation of the above micro-mechanism on the site of the earth and murals. The study found that the morphology and structure of sodium sulfate in the earth’s ruins are dynamic. This work makes up for the limitations of previous research and understanding. This study will provide a scientific reference for preventing, delaying and predicting the occurrence and development of soil relics salt damage.