南极洲万达盐湖底部现代沉积物中黄铁矿物的发现及其地球化学意义

The discovery and the geochemical significance of pyrite mineral in moden sidments of the bottom of Vanda Lake, Antarctica

作者首次在南极洲万达盐湖底部现代沉积物中发现了自生的黄铁矿颗粒。该发现对解释万达湖还原层湖水中铁离子的垂直迁移具有重要地球化学意义。基于1.目前万达湖还原层湖水的FeS_2活度积(IAP)大于它的热动力溶度积(Ksp)2.该湖还原层湖水的pH—pE数据组落在黄铁矿的pH—pE相图中的黄铁矿相区。相图预测到现在万达湖还原层湖水有析出自生黄铁矿的可能性,而且进一步被X射线衍射分析及电镜扫描等资料证实,湖底沉积物中存在黄铁矿矿物。这样,就有力地解释了还原层湖水中铁离子浓度降低的原因—由于黄铁矿颗粒的形成而迁出了水中铁离子。

The authors found firstly the self—generating pyrite particulate in modern sediments of the Vanda Lake bottom in Antarctica, which has an importmant geoehemjcal signilicance for interpreting the vertical migration of iron ion in the reducing layer of Vanda Lake water. Based on 1.The Ion Activity produet(IAP)of FeS_2 is larger than its thermodynamic solubility product(K_(sp) in redticing layer of the Vanda Lake water at present. 2.The data set of pH—pE in reducing layer Of this Lake enter into the region 0f pyrite phase Of pH—pE phase digram of pyrite mineral, we predjct that the possibility of the self—generating pyrite exists in the reducing layer of Vanda Lake water now, furthermore, that pyrite is present in sediments of the Lake bottom. This possibility has been proved by X—ray diffraction analysis, electron microscopic seanning and photograph. Therefore, the cause that the concentracion of iron ion decreases in the redticing layer of lake water has been powerfully interpreted—Iron ion in water is removed due to the formation of pyrite particulate.