海水蒸发时蒸气相硼的浓度及硼同位素分馏研究

A Preliminary Study of the Boron Concentration in Vapor and the Isotopic Fractionation of Boron During Evaporation of Seawater

本实验目的是研究在空气流的条件下海水－空气界面硼的行为。将２５℃和３５℃的干燥空气流以非冒泡或冒泡的方式通过海水表面或通入海水，采用冰冷凝器和ＫＯＨ溶液浸泡过的纤维素过滤器收集空气流中的硼，当无硼空气流在海水面上通过时，硼会被蒸发而进入空气流中，温度越高，硼含量也较高。空气流通过海水的冒泡试验中，空气流中的硼含量与空气流流量成正比，在此情况下，空气流中的硼主要来自雾化的小液点海水。非冒泡试验中收集的硼同位素分馏表明，较轻的硼同位素１０Ｂ富集在空气流中，表明海水蒸发时，硼同位素分馏主要由动力因素所引起。

A laboratory experiment was undertaken to investigate the behaviour of boron at the sea- water-air interface under air flow conditions. Dried air at 25℃ and 35℃ was passed over or bub- bled through seawater at the same temperature. A combination of ice- chilled condensers and KOH impregnated cellulose fibre filters was used to collect boron from the reacted air. When air stripped of boron was passed over the seawater, boron was found in the reacted air, and its concentration was higher in the higher temperature test. In the tests where air was bubbled through seawater the con- centration of boron in the reacted air was directly proportional tl the air flow rate. In this situation the boron in the reacted air was mainly introduced as a spray of microdroplets. Isotopic analysis of the collected boron in the non-bubbled tests yields fractionation factors which demonstrate that the lighter isotope, 10B,is enriched in the reacted air. This indicates that the isotopic fractionation of boron during evaporation of seawater is mainly caused by a kinetic effect.