莫高窟崖体可溶盐分布特征研究

Distribution of soluble salts in the cliff strata of the Mogao Grottoes

通过对莫高窟崖面不同高度取样,运用经典溶液化学的研究方法,调查研究莫高窟崖体中所含硫酸钠(Na2SO4)和氯化钠(NaCl)以及中溶盐硫酸钙(CaSO4.2H2O)的分布。经过水化学分析,浸出液的水化学类型主要为SO4.Cl—Ca.Na型,离子为引起壁画疱疹、粉层起甲、颜料层粉化、颜料层片状脱落、壁画地仗酥碱的主要成分。同时,查明了莫高窟崖体物质组成,数据显示,崖面砾岩以大孔隙为主,渗透性变化范围广,有利于盐分溶液渗透。分析结果表明,莫高窟崖体上盐分随高度的分布规律受地表淋滤下渗和历史上风积沙掩埋期的毛细上升等综合因素影响,且后一种作用引起的盐分聚集有可能是底层洞窟壁画病害的主要原因。

Taking the salt distribution of the Mogao Grottoes cliff as the research object,this paper utilizes the classical solution chemistry method to study the occurrence of soluble salt such as sodium sulfate（Na2SO4）,sodium chloride（NaCl） and calcium sulphate（CaSO4）.Based on the analysis of the solution chemistry at different heights of the Mogao Grottoes cliff,the aqueous solution of the cliff rock is composed of a typical chemical composition and is of Ca.Na—SO4.Cl type.The composition of the Mogao Grottoes cliff is also investigated,and results show that the permeability of the cliff conglomerate changes greatly,which is helpful in the migration of water and salt.Research results indicate that the salt distribution with height is affected by leach infiltration and capillarity in the sand buried period,and the capillarity possibly causes the salt migration of the Mogao Grottoes mural diseases.