ANOMEALY OF FLUORINE IN A SEDIMENTARY SYSTEM, WESTERN ANTARCTIC OCEAN

Fluorine content in bulk sediment and its pore water in Western Antarctic Ocean is 200～395μg/g and 1.18～1.92ug/ml respectively, far below the average reported previously in the world oceans (540 ug/g and 2.7t~g/ml, respectively). This study also shows that the distribution of fluorine in the sediments of the area is mainly controlled by the chemical composition of the material from the surrounding islands, and the element seems to be mostly incorporated in the hornblende, thus the correlation between the element and the hornblende amount in the sediments can be expressed statistically as following: F=217+ln Vh. The low concentration of fluorine in the pore water is largely due to the weak weathering process on the islands and the precipitation of the element with calcium. It can be indicated well by the lower value of anion-exchangeable (HCO_3~-) F- in the studied area, which is only about one tenth of that in Pacific Ocean and a quarter in South China sea and a half in the sea east of Zhejiang. In a

ANOMALY OF FLUORINE IN A SEDIMENTARY SYSTEM, WESTERN ANTARCTIC OCEAN

Fluorine content in bulk sediment and its pore water in Western Antarctic Ocean is 200-395μg /g and 1.18-1.92μg / ml respectively, far below the average reported previously in the world oceans (540μg / g and 2.7μg / ml, respectively). This study also shows that the distribution of fluorine in the sediments of the area is mainly controlled by the chemical composition of the material from the surrounding islands, and the element seems to be mostly incorporated in the hornblende, thus the correlation between the element and the hornblende amount in the sediments can be expressed statistically as following: F=217+ln Vh. The low concentration of fluorine in the pore water is largely due to the weak weathering process on the islands and the precipitation of the element with calcium. It can be indicated well by the lower value of anion-exchangeable (HCO3-) F- in the studied area, which is only about one tenth of that in Pacific Ocean and a quarter in South China sea and a half in the sea east of Zhejiang . In addition, the decomposition of the organic matter in the sediment will probabally provide fluorine to the pore water, which can be easily captured by the solid phase. Therefore, the possible mechanism of the element's transition and redistribution in the sedimentary system can be preliminarily described as: F_Org Early diagenetic decomposition F_pore water Calcium compounds F_solid phase