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海洋や湖の堆積物を対象にした古地磁気学・環境磁気学の研究では，残留磁化や初磁化率のパススルー測定が広く用いられている。パススルー測定では必然的に出力がセンサーの応答曲線によって平滑化や変形を受けるため，堆積物の正確な信号を得るには測定結果のデコンボリューションが必要となる。デコンボリューションの手法は，赤池ベイズ情報量規準(ABIC)を最小化することによって最適な平滑化の条件を得て残留磁化のモデリングを行うことによって改善されてきた。本研究では，同様のアルゴリズムに基づき，まず試料全体に一つの平滑度を設定し，さらに強い磁化率のピークを伴う範囲に第2の平滑度を導入して，初磁化率のパススルーデータのデコンボリューションを行うプログラムを作成した。このプログラムを秋田県田沢湖のUチャネル試料に適用し，デコンボリューションの結果が個別試料の測定値と一致することが確かめられた。しかし，鋭いピークの箇所では誤差を伴う変動が生じており，火山灰やイベント層を含む試料のデコンボリューション手法にはさらに改良が必要なことが示唆された。, Pass-through measurement of remanent magnetization and magnetic susceptibility of U-channel samples is now widely used in paleomagnetic and environmental magnetic studies of marine and lacustrine sediments. Since the output from pass-through measurement is inevitably smoothed and distorted by the response function of the sensors, deconvolution of the measurement result is necessary to obtain accurate signals of the sediment. Methods of deconvolution have been improved by modeling the remanent magnetization as a smoothly changing function by minimizing Akaike's Bayesian information criterion. In this study, we developed deconvolution programs for pass-through magnetic susceptibility data based on the same algorithm, first by using a single smoothness parameter for the entire sample and then introducing an additional parameter for the interval with a strong susceptibility peak. Applying these programs to U-channel samples from Lake Tazawa, Akita Prefecture, it was confirmed that results of the deconvolution well correspond with susceptibility of the discrete samples. However, the interval with a sharp susceptibility peak produced noisy erroneous variation, suggesting that further improvement is necessary for deconvolution of the samples including tephra or event layers.

We reviewed the restults of previous studies on paleoclimate and paleoenvironment in and around the Japanese Islands during the Last lnterglacial period. Sediment cores recovered from deep-sea settings around the Japanese Islands provide valuable information in understanding the ocean paleoenvironment and age framework since marine isotope stage 6. Analyses of pollen, diatoms, and total organic carbon in lake sediments have contributed to clarifying the land climate in detail, in combination with age constraints provided by tephra marker beds. Great progress has been made in tephra stratigraphy and the identification of tephra marker beds, which provide the key to correlating land and marine data, as shown in the case studies on Lake Biwa and the Takano Formation. Because several widespread tephra marker beds are 90 to 100 ka in age, it is possible to reconstruct the paleoclimate of this period at high resolution, both temporally and spatially,integrating local and regional environmental information for both land and marine settings. Such results may be important in the near future for local and global climate forecasting., 更新世後期の最終間氷期を中心に,日本列島陸域および周辺海域の古気候･古環境変動について研究の現状を紹介し,今後の課題を提起した.海洋域では海底コアの多面的な解析が,海洋環境と古気候変動の解明に大きく貢献している.陸域の研究では,長期間に及ぶ連続堆積物を用いた花粉分析や珪藻分析,有機炭素分析によって高精度の古気候復元が試みられている.海域と陸域を繋ぐ鍵として広域テフラの有用性は高く,琵琶湖堆積物や高野層に挟まれた指標テフラは古気候を時間･空間的に結合させて復元する鍵となる.特に指標テフラ密度の高い9 - 10万年前の日本列島とその周辺は,有望な研究対象である.このように,テフラを介して海域と陸域の古気候･古環境情報を比較･統合して,高時間分解能で総合的な古気候復元を行うことは,日本列島の地域性を明らかにするとともに,汎世界的な気候変動のシステムを理解する上でも必要な貢献となる., Article, 地質学雑誌 115(7): 301-310(2009)

Heavy metal concentrations (Pb, Cd, Mn, Ni, Zn and Hg) from surface sediment and those in every 2cm segment of the core sample from Maizuru Bay were examined in 2008. The highest Pb concentration. (2,884μg/g dry) in surface sediment was detected from the sample near the lead battery recycle factory. This concentration was inferior level applied to the environmental index in Norway. It is possible to estimate the times when release of Pb began in this area from the profile of Pb in sediment core. The concentration of Pb in the top of 5cm was clearly higher than in the other lower part of sediment layers. The Pb concentrations in land soil around th lead battery recycle factory not only under the sea but also on the land. It was proved that some antipollution steps which have been taken were not enough.

Risk of the drug resistant bacteria infection has been pointed out by WHO, especially in developing country, recently. Potential influence of pollution by Pharmaceutical and Personal Care Products(PPCPs) is concerned. In addition, Perfluoroalkyl substances(PFASs) such as perfluorooctanesulfonate(PFOS) have received world attention in recent years because of their persistence in environment and potential risk. In this study, we investigated PFASs and PPCPs in river and sediment samples collected from India from 2011 to 2014 . The field survey result was discussed from the viewpoint of different environmental, industrial and social situation between India and developed country.