Geochemical study of hydrothermal solution using chemical elements as tracer.

海水和沉积物样品在1984-1986年间由R/V采集。来自马里亚纳海槽和冲绳海槽的“东海-大阪丸”，那里的热液喷发已被“阿尔文”和“新海-2000”证实。分析了海水中的营养物质、溶解氧、甲烷、常量元素和锰，以及沉积物中的几种化学成分。钠、钾、镁、钙与盐度的比值从表层到底层是一致的，在底层略有增加。马里亚纳海槽海水柱中锰的浓度范围为0.71~2.48nmo1/kg，表现为表层高、下层低、底层又增加的规律。86年3月冲绳海槽水中锰的含量为0.18-3.64nmo1/kg，从中部约700m到底部约1500m呈急剧上升趋势。86年11月，在冲绳海槽底部上方观察到锰浓度异常，约为5nmo1/kg。这些锰含量异常可能与热液活动有关。冲绳海槽甲烷浓度在30-50nl/L之间，在底部以上略有增加。根据Fe-Mn-(Ni+Cu+Co)x10的三角图推测这两个海槽的沉积物具有热液特征。冲绳海槽沉积物孔隙水中总碳酸盐和磷酸盐的平均浓度分别为4.06和9.29 mm/L，高于沉积物上方的海水。

Sea water and sediment samples were collected in 1984-1986 by R/V. "Tokai-Daigaku Maru" from the Mariana and the Okinawa Troughs,where hydrothermal eruption has been confirmed by "Alvin" and "Shinkai-2000". Nutrients,dissolved oxygen,methane,major elements and manganese in sea water, and several chemical components in the sediments were analysed. The ratios of Na,K,Mg and Ca versus salinity were uniform the surface to the bottom waters and showed a slight increase just above the bottoms. Manganese concenteation in seawater columns in the Mariana Trough ranged 0.71-2.48 nmo1/Kg,and was high in the surface and low in the lower layer and then increased again in the bottom. Concenteation of manganese in the Okinawa Trough waters on March'86 ranged 0.18-3.64 nmo1/Kg, showing sharp increases from the middle,about 700m,to the bottom,about 1500 m,layers. Anomalies of manganese concentration,about 5 nmo1/Kg,were observed just above the bottoms in the Okinawa Trough on November'86. These anomalies of manganese concentration may be related to the hydrothermal activity. Methane concentrations in the Okinawa Trough ranged 30-50nl/l and showed a slight increase above the bottoms. The sediments in these two Troughs were presumed to be of the hydrothermal characteristics from the triangle diagram of Fe-Mn-(Ni+Cu+co)x10. Average concentrations of total carbonate and phosphate in the pore waters of the sediments in the Okinawa Trough were 4.06 and 9.29 mM/l resp.,These values being higher than those in seawater just above the sediments.