Survey and Exploration of Salts Species and Distribution in Laoshan Han Tomb Earthen Sites

Soluble and slightly soluble salts resulted in the efflorescence, flaking, whitening and block off and other serious diseases of earthen site surface in Laoshan Han Tomb Site. In this study, the components and contents of soluble salts at different positions were analyzed by X-ray fluorescence spectrometry (XRF), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and ion chromatography (IC) methods, qualitatively and quantitatively. And the possible mechanism of the damage of salt to the soil structure of the site was proposed. The results showed that the main components of the soluble salts were Na₂SO₄, Na₂SO₄·10H₂O, NaCl, Na₁₂Mg₇(SO₄)₁₃·15H₂O, and the slightly soluble salt were CaSO₄ and CaSO₄·2H₂O. In addition, a small amount of CaCl₂, KNO₃, KCl, MgCl₂, K₂SO₄ and MgSO₄ existed in soil samples. With the increase of the sampling depth, various kinds of salt contents and types gradually decrease. The results indicated that the distribution of salts was closely related to the water movement and the existed environment. The obtained results provide useful information for the conservation of earthen sites.