南海海水25℃等温蒸发实验研究

EXPERIMENTAL STUDY OF 25℃ ISOTHERMAL EVAPORATION OF SEA WATER FROM THE SOUTH CHINA SEA

用南海海水在２５℃条件下进行等温蒸发实验，获得了海水蒸发残余液相中不断变化的氢、氧同位素比值及蒸发析出的石膏、泻利盐、光卤石等矿物结晶水中的氢、氧同位素比值，获得酸碱度、氧化还原电位及密度等数据。由于南海海水在化学组成及氢、氧同位素组成上都与平均大洋水非常相近，所得数据可作为研究海相盐类沉积及古海盆地卤水成因的依据．

he water sample has been collected from South China Sea. It is consistentwith the mean ocean water in the contents of major ions as well as H and O isotopes. The isothermal evaporation of the sea water has ben carried out in laboratory, where the evaporadon temperature is strictly controlled at 25℃. During theevaporation, the solid phases of salts separate frem water in the same sequence astEe former researchers reported.The H and O isotope ratios have been determined on both the changing residual water and the crystallization water within the deposited salts (including Gy, EPand Car) in the course of evaporation. The H and O isotope fractionation duringisothermal eyaporation of sea water has been displayed well in the distribution pattern of the isotope data. The enrichment of heavier isotopes continues to the latestage of Halite crystallization. Then, the δ13O and δD reach their highest valuesof 35‰ and 130‰ respectively. When Ep separates, the H and O isotope ratiosbegin dropping and dropping. On the other hind, the H and O isotope ratios ofthe crystallization water within the deposited salts increase from Gy, Ep to Carwhile the evaporation goes on. In addition, pH, Eh and specific weight valueskaye been gauged for the changing residual water during the evaporation, whichhave been contrast with the isotope data.The above result is up-to-date. It could provide a basis to further discussionabout the formation of brine and the process of marine salt deposits.