The top clinometer is a newly developed payload tool which enables a submersible vehicle to directly measure orientation of planar geological structures (e.g. bedding planes, faults) on seafloor outcrops. It consists of a disc and central vertical bar, both graduated at 1 cm scales, and a handle. On seafloor outcrops, the disc is placed on the geological surface of interest by a manipulator, and is captured by a still camera. The orientations are determined via simple onboard graphic analyses of the images obtained and the submersible log data. Strike and dip of the surface structures are routinely calculated by a macro program within a Microsoft Excel worksheet. Theoretical and laboratory tests suggest errors of the measurements in the same order as magnetic clinometer compasses commonly used for on-land geological surveys. Camera installation angles to the submersible Shinkai 6500 were also calibrated based on on-deck tests during R/V Yokosuka YK08-05 and YK10-13 Leg2 cruises. Results of three practical measurements suggested that speed of the operation depends heavily on the time spent looking for the target surfaces and the time for communication between operators and scientists. Besides these factors, a measurement can be taken in as little as five minutes. This simple and quick method improves the quality of structural measurements for submarine geology.

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海洋地球研究船「みらい」では,採水にニスキン−X採水器を取り付けたCTD採水システムを使用している. ニスキン−X採水器は蓋閉用のスプリングが採水器外側に配置され, ボトル内部へのゴムや微量金属による汚染を極力排除できる仕組みとなっている. 通常, 一次生産量測定用のサンプリングには海水サンプルへの微量金属等の汚染防止を徹底するため, 内部にテフロンコーティングを施し, ボトル内部及び部品各種を酸洗浄した採水器をクリーンニスキンとして使用している. クリーンニスキンとその他のノーマルニスキンで採水した場合に, 実際に一次生産量に差が生じるのかを確かめたところ, ノーマルニスキンで採水した場合に一次生産量測定値が激しく低下した. その差を生じる原因を把握するための追加実験を行うと, ノーマルニスキンで使用しているニトリルゴム製Oリングが一次生産を阻害していることが明らかとなった.

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During the interval from 4.9 to 4.1-3.7 Ma in the early Pliocene, extinct fossil freshwater diatom species Aulacoseira praeislandica and near-shore marine fossil diatom species Koizumia tatsunokuchiensis are abundant at DSDP Site 436 on the abyssal floor far east over the Japan Trench as sediment trap. The close correspondence of abundances of two characteristic diatom groups with occurrence of coarse volcanic debris, increase of eolian material, and large numbers of fecal pellets in the early Pliocene sediment at Site 436 suggests deposition by the settled water column after being transported to the area through the Kuroshio-Kuroshio Extension system driven by winds and the atmosphere by the typhoons during a warming climate interval. The early Pliocene is considered to be the warmest interval and a period of reduced latitudinal thermal gradients. Tropical cyclones (hurricanes and typhoons) and ocean wind-driven circulations are simulated by modeling studies to have increased during the early Pliocene because of a vast pole-ward expansion of the tropical warm pool that associated with expanded El Niño-like conditions. And the Pliocene coral records support that stronger winds in the tropical Pacific act as a possible driving force of the western Pacific warm pool. Tropical storms in the early Pliocene increased ocean vertical mixing and transported heat pole-wards. Atmosphere-ocean circulations are considered as efficient media for the upwelling and transportation. The Pliocene extinct freshwater and near-shore marine diatoms at Site 436 may have been derived from the continent or/and sea bottom by atmosphere-ocean dynamics along frontal boundaries moved northward off Japan during the warm early Pliocene.

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「かいこう7000 II」は, 深度7000mまで潜航可能なRemotely Operated Vehicle (ROV) である. 「かいこう7000 II」はランチャーとビークルの2つで構成され, 母船とランチャーは1次ケーブル, ランチャーとビークルは2次ケーブルで繋がれている. 従来の構成では, 1次ケーブルにはシングルモード (SM : Single Mode) 光ファイバが採用され, 2次ケーブルにはマルチモード (GI : Graded Index) 光ファイバが採用されていた. このGIの伝送量は, ハイビジョン映像等の大容量データを伝送するには不十分で, 大容量通信に適したSMへの換装が求められていた. そこで, 海洋研究開発機構では2009年よりSMを採用した2次ケーブルへの換装を進め, 2011年2月の海域試験での通信試験において「かいこう7000 II」の光伝送経路のSM化を達成した. SM化により, 伝送容量が飛躍的に向上し, ハイビジョン映像等の大容量の通信が可能となった. 本報告では, 「かいこう7000 II」の光伝送経路の概要と, 2011年2月に行われた海域試験の結果について報告する.

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