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The age of ancient iron artifacts can be measured by using carbon component contained in metal iron that was included during the iron producing or iron reprocessing stages. To extract carbon from iron artifacts in a form of CO2, a quartz tube has been used for metal iron combustion at the temperature of 1000°C for about 15 hours. We tested the quartz tube combustion method successfully of metal iron in a fine flake condition of almost 1mm in size. Almost 87 % recovery in average for 24 samples from a standard iron material was attained when metal iron weight is about 25% of CuO used as an oxidizer. The CO2 of about 1mg carbon was changed to graphite and 14C dated with the HVE 14C-AMS system at Nagoya University as well as NEC 0.5MV compact AMS at Paleo-Lab Co. Ltd. One of the common iron artifacts in Japan is Japanese sword, owned traditionally by samurai, a Japanese warrior, and used during battles. At the present time, Japanese swords are one of excellent art collections, and many fake swords exist in the market. Traditionally, Japanese sword has been authenticated by experts based on visual outlook of them and judged real ones out of fakes. A more scientific method was required for judging the original sword. We have analyzed several iron flakes of about 1mm in size collected from Japanese swords in the course of grinding and re-sharpening them. The analyzed swords were believed to have produced in the 5th century and after, by the name of the manufacturer inscribed on the surface of the sword, and/or by the traditional judgment by experts. The obtained 14C dates for the sword samples were calibrated with IntCal20 and compared with the authorized production dates by visual analysis. The 14C ages were almost consistent with the traditional judgments. We consider that 14C dating is a useful tool to certificate the visual judgment of the swords by experts and to accept existing historical documents about them. In addition, iron rust samples are commonly excavated from archeological sites in Japan and in foreign countries. We have tested four rust nail samples from archeological sites in India, to collect carbon component successfully by the quartz tube in the same way as pure metal iron. The nail samples were covered by rust on the surface, but the samples should contain metal portion, because they reacted on the magnetic filed. The carbon content of the rust nails was from 0.2 to 0.5 % in weight ratio, similar to that of pure metal iron samples. The obtained 14C ages were consistent with their archeological chronology.

The Tokachi Plain in Hokkaido, Japan, has always been a stable food supply base for Japan, supported by large-scale agriculture, including dry-field farming, mainly of beans and potatoes and dairy husbandry since 1875. In 2021, the authors performed pollen analysis, AMS14C dating, vegetation and soil property surveys on a 1.6 m deep borehole obtained in a wetland forest at an altitude of 275 m in Memuro-cho, Fushimi, at the foot of the eastern Tokachi side of the Hidaka Mountains in 2002. The study clearly shows the characteristics of vegetation changes. In regard to the changes that occurred in the Fushimi wetland, tephra released from volcanoes in the distance was thickly piled up, changing into a wetland with Lysichiton camtschatcense, on which a cool-temperate deciduous broad-leaved forest was established, and the pollen zone D was formed. The AMS14C age at a depth of 1.44 m is 2310–2112 cal BP ± 2σ (95.4%) (NUTA2-27097). Below this point, in the pollen zone A, coniferous trees receded and deciduous broad-leaved trees predominated. Samples from 1.0 m depth (sample No. 51) to 1.4 m depth (sample No. 69) contain a small amount of Selaginella selaginoides spore (pollen zone B). In addition, the C pollen zone includes a little more spruce (maximum value of 35% at a depth of 72 cm, sample No. 39) and Abies sachalinensis. On the other hand, in Churui, located 40 km southeast of the aforesaid site, the molar teeth and almost the entire bodyʼbone of the Palaeoloxodon naumanni’ were excavated in 1969. The result from the pollen analysis on the stratum 17c-5, performed by Ohe and Kosaka (1972) and Hoshino et al. (2021), where the bones were discovered, indicates that the climate of Churui was milder than that of Fushimi, because there used to be a Fagus crenata forest there. The period turned out to be 120,000 years ago. In recent years, while global warming has become a serious social issue, there was a time in the past when the climate was much warmer., 北海道十勝平野は1875年以降、豆類、馬鈴薯中心の畑作、酪農など大規模農業による日本の食料供給基地である。その日高山脈東部十勝側山麓部にある芽室町伏美の標高275mの湿性樹林で、2002年に深さ1.6mのボーリングコアを得て、花粉分析を行い、2021年AMS14C年代測定と周辺の現在の林相・植生調査・土性調査により花粉種属から林相と林床植生の推移の特徴を明らかにした。伏美湿性地は、遠隔テフラ堆積物が厚く堆積してミズバショウのある湿地となり、この上に落葉広葉樹を主とする冷温帯性の落葉広葉樹林が成立し、花粉帯Dを形成した。深さ1.44mでのAMS14C年代は2310–2112calBP±2σ(94.9%)（NUTA2-27097）であった。この年代測定点の下で針葉樹が減少し落葉広葉樹が優勢である（A花粉帯）。深度1.0m（試料番号51）から深度1.4m（試料番号69）はコケスギランの胞子を少量伴う（B花粉帯）。なお、C花粉帯はトウヒ属やや多く（試料番号39深度72cmで最大値35%）、トドマツもやや多い。一方、ここより南東40kmの近距離にある忠類ナウマンゾウ臼歯とほぼ全身の発掘が1969年に行われ、その骨の産出層準17c-5から得られた花粉分析結果（大江・小坂,1972）と星野ほか（2021）は、ブナを伴い今回の伏美より温暖な気候を示し、その時代は12万年前であった。近年、地球温暖化が社会問題になっているが、より温暖な気候に見舞われていた時代が過去に存在していたのである。

A Model 4130-AMS by High Voltage Engineering Europe B.V., dedicated to 14C measurements was delivered to Nagoya University in 1996/97. Acceptance tests of its performance were completed in 1999, and a routine operation started in mid-2000. The number of targets measured was 330, 1430, 2077, 1003, 1,979, 1679, 1772, 1115, 1339, 866, 1300, 1701, 1449, 1634, 1351, 1741, 1156, 466, 900, 1345, 653 and 1123 in each year from 1999 to 2020, respectively, and total number of targets measured by the end of 2020 is 28,408. The problems in 2020 are; (1) instability of C- beam intensity was a big problem for high statistical 14C measurements. Intensities of C- beam gradually decreased to 1/5 from the begging of 14C measurements in about 15 hours. We could not increase the beam intensity any more, even increasing Cs sputtering ions by heating up the Cs reservoir temperature. We tried to shut the ion source down and power on again, but not successful. However, the ion source was opened and cleaned to successfully recover the ion beam intensity. We applied this method for routine 14C measurements, although it wasted a lot of time; (2) the power supply for the recombinator magnet was out of order. The control of DC current for the magnet did not work well. We replaced a power transistor on the circuit board to repair it; (3) a plunger unit to grasp the target for loading and unloading it to the sputtering position was out of order. The four fingers of the plunger were partly broken and could not grasp targets firmly to move them from carrousel to the sputtering position and back. We replaced it to a new one; (4) because of instability of DC voltage of about 90 [V] supplied for a Y- steerer in the ion source, with the fluctuation of about ±5 [V], C- beam suffered instability in the direction of the beam. A part of the C- beam even hits the wall of the beam line. The power supply for the Y-steerer was repaired; (5) a step of initialization to start up the target handling in the ion source could not work well. A target movement control by computer was out of order. We replaced a X-motion motor that could be broken, and changed 6 units of light-guide cable for communication of signals to control the end parts of the ion source unit. In particular, the replacement of lightguide cables was effective for the successful handling of the targets., 名古屋大学宇宙地球環境研究所では、1997年3月に完納されたHigh Voltage Engineering (HVE)社製Tandetron (Model 4130-AMS)が放射性炭素（14C）測定専用装置として運用されている。最大の特徴は、イオン入射部にリコンビネーターを備えて、炭素の3種の同位体が同時に測定でき、導入された当時は14C測定において高性能を誇っていた。しかし、今になるとる14Cしか測定できない事が利用拡張の妨げになっている面もある。2019年にはわずか653個しか測定できなかった。大きな故障はなかったものの、細かい不具合が重なり、試料の測定が進まなかったことによる。2020年は1123個のターゲットを測定した。しかしこの間も、測定精度に関わる、イオン源の炭素ビーム出力に大きな問題が発生した。炭素ビーム出力の経時変動が顕著になり、測定の始めは、充分な炭素ビーム出力があるものの、数時間を経ると、炭素ビーム出力が低下する。対策として、セシウム溜の温度を上昇させても、あまり効果がなく、炭素ビーム出力は回復しない。この事象が発生して以来、イオン源のターゲット電圧電源、引出電圧電源、シリコン冷却系のパイプの詰まりの有無、セシウムイオナイザー電源、セシウム温度制御装置など、各種の付属装置などの交換を試みてきた。2011年3月上旬にイオン源のX-motorの取替を行い、さらに、光ケーブルの交換を行ったことから、これまでに問題があった症状が出なくなっている。現在のところ、問題は、まだ解決していないが、今後、注意深くテスト・ランを進める必要がある。この間に、最近になって炭素ビームの変動が大きくなり、12C, 13C, 14Cの測定の安定性が問題であった。この問題については、炭素ビームの最上流部にあるイオン源のY軸方向のビーム偏向を制御するY-steerer電源の出力が周期的な変動をしている事が原因となっていることが判明した。過去のデータを調べると、10年前にも小さな変動があり、近年その変動が次第に大きくなってきた。しかし、このAMS 装置では、リコンビネーターを用いて同時測定を行っているため、この電源に起因するビーム強度変動は12C, 13C, 14Cで均等に影響するため、この変動の効果がキャンセルして、14C/12C比の測定には影響をほとんど及ぼさなかった。このY-steerer電源の修理を行うまでに沢山の試料を測定したが、得られた14C年代は、非常に調和的な値であったことから、利用者は安心して頂きたい。初めに、リコンビネーターの悪口を書いたが、有用であった面も挙げられる。

The Karako lowland, located about 13 km west of the Unzen Volcano, has thick bog sediments consisting of peat and mud layers. These sediments are expected to record the activity history of the Chijiwa fault and Unzen Volcano. To detect those histories with high accuracy, we obtained several sediment cores and conducted radiocarbon (14C) dating with AMS. The results were compared with ground penetrating radar cross-sections to examine the formation process of the wetland deposits., 雲仙火山の約13km西方にある唐比低地には泥炭層や泥層からなる湿地堆積物が厚く分布しており、それらの堆積物には千々石断層や雲仙火山の活動履歴が記録されていることが期待される。それらの履歴を精度よく検知するために、複数本のボーリングコアを掘削して放射性炭素年代値を測定した。それらの結果を地中レーダ探査断面と対比して湿地堆積物の形成過程を検討した。

The 10.2 m core sample collected from the Higashinopporo Wetland, the east side of the Nopporo Hills in the central part of the Ishikari Plain, in 1997 has shown the presence of temperate deciduous broad-leaved forests and the continuous appearance of a small amount of Fagus crenata pollen. The authors collected the surface soil and conducted pollen analysis at 30 survey points set in 2020 within a range of 7 km east-west and 6 km northsouth from the three planted Fagus crenata parent tree groups in the Higashi-Nopporo Wetland region. The result indicates that fallen Fagus crenata pollen was confirmed at an appearance ratio of nearly 20% below the crown of the trees, while the ratio was just 0-1% in the south-west direction. The authors reconsidered the survey results obtained from a pollen analysis on the Oxygen Isotope Stage 5e, which was conducted in 1970, when almost a whole fossil of Palaeoloxodon naumanni was excavated in Churui, the Tokachi Plain, the eastern part of Hokkaido. The research has proven that the elephants lived in the period when the climate was warmer than now by 11 degrees or more Celsius and temperate deciduous broad-leaved forests prospered. Sedimentation in peat stratum in the Higashinopporo Wetland began in mean 5917±46 calBP, 1σ (NUTA2-27702), which nearly corresponded to the height of Holocene glacial retreat period, around 6,000 years ago., 石狩平野の中央部にある野幌丘陵の東側、東野幌湿原で1997年に採取した10.2mコアは温帯性落葉広葉樹林の存在を示し、少量のブナ花粉が連続出現していた。この地域には植栽され大木になったブナ親木集団が三つあり、その周りの東西7km、南北6kmの範囲内に2020年に設定した調査地点30カ所で表土を採取し花粉分析した。ブナ大木の樹冠下方では20%近い出現率でブナ落下花粉が存在したが。南~西方向へは0~1%の出現率であった。北海道東部の十勝平野の忠類で1970年にナウマンゾウ化石ほぼ1体分が発掘された時の酸素同位体ステージ5eの花粉分析を再考察した。現在より11ºC以上温暖な温帯性落葉広葉樹林植生が発達していた時代にこのゾウが生きていたことが判明した。東野幌湿原における泥炭層の堆積の始まりは縄文海進最盛期の6,000年前に近い5917±46calBPであった。

Pollen analysis was conducted on a 750 cm long sediment core from a wetland (21°57'01" S, 157°55'41" W) on the shore of Lake Tiriara, Mangaia Island, Cook Islands. The results showed that fern spores were more abundant from the lowest layer, and secondary vegetation elements such as Trema pollen, and weed elements such as Chenopodiacea pollen, also occurred, confirming that deforestation had already occurred. Conversely, native forest elements such as Ficus and Elaeocarpus pollen grains are present, suggesting that some native forests were still intact. Human settlements on the island of Mangaia were initially limited to the coast, but by the 16th century (1500 AD) they had expanded inland. Approximately 16th centuries of inland migration corresponds to a depth of 300 cm. During this time, tree pollen grains such as Ficus almost disappeared, and instead Arecaceae and Poaceae pollen grains, and fern spores rapidly increased. This is thought to be the result of the migration of humans from coastal areas to inland areas and further deforestation. Coconut (Cocos nucifera) and whistling pine (Casuarina equisetifolia), which were probably introduced by Polynesians, are estimated to have been brought to Mangaia Island in 1000 cal AD and 1400 cal AD, respectively. In addition, Caribbean pine (Pinus caribaea) increases from around 1980 cal AD, and this species was planted by the Cook Islands government from 1984 AD to prevent soil erosion, with concordant results., クック諸島マンガイア島のTiriara湖湖畔の湿地（21°57ʻ01“S, 157°55ʻ41“W）から得られた全長750cmのコア堆積物の花粉分析を行った。その結果、約2000年前の最下層よりシダ胞子が多く、二次植生要素のウラジロエノキ属なども出現することから、この時期にはすでに森林破壊が起こっていたことが確認できた。しかし、原生林要素のイチジク属やホルトノキ属も出現しており、原生林はかなり残っていたと思われる。1200~1500cal AD頃を示す深度400~300cmではイチジク属などの木本類花粉はほぼ出現しなくなり、代わりにヤシ科やイネ科、シダ胞子が急増している。沿岸部から内陸部に人類が移動し、さらに森林破壊を行った結果であると考えられる。この時期は考古学的には海岸から内陸に拡散した時期に相当する。この移行期に、イチジク属などの木本類花粉はほぼ出現しなくなり、代わりにヤシ科やイネ科、シダ胞子が急増している。沿岸部から内陸部に人類が移動し、さらに森林破壊が進行した結果であると考えられる。ポリネシア人が移入させたと思われるココヤシやトクサバモクマオウは、それぞれ1000cal ADと1400cal ADにマンガイア島に持ち込まれたと推測される。また、カリビアマツは1980cal AD頃から増加するが、本種はクック諸島政府により土壌侵食を防ぐ目的で1984 ADから植林されており、調和的な結果が得られた。

日本上空の成層圏、および南北両極域の地上基地で採取された大気試料のΔ14CO2を分析し、その時空間変動を明らかにした。成層圏におけるΔ14CO2は、対流圏大気の流入経路の違いを反映して対流圏界面付近から成層圏中部（高度22km以上）まで急増し、それ以上の高度ではほぼ一定値を示した。成層圏中部以上でのΔ14CO2の経年減少率は一定ではなく、宇宙線起源14C生成率推定値との相関が見られた。南北両極域においてΔ14CO2の経年減少が観測された。北極・ニーオルスンで観測されたΔ14CO2の季節変化について原因を考察し、成層圏からの14CO2輸送と陸上生物圏のCO2吸収、そして化石燃料起源CO2放出が季節変化に寄与している可能性を指摘した。さらに炭素循環モデルを用いて現在の対流圏におけるΔ14CO2の経年変動要因を推定した結果、対流圏大気と陸上生物圏及び海洋との14CO2の非平衡状態はほぼ解消し、化石燃料起源CO2の対流圏への放出がΔ14CO2変動の最大の要因であることが明らかになった。

The Kyoho eruption of Shinmoedake volcano in the Kirishima volcano group has been dated to 1716-1717 AD based on descriptions in ancient documents. This period is difficult to calibrate calendar years from radiocarbon (14C) ages, but the correct age can be obtained by applying 14C wiggle-matching. In this study, five tree trunk samples (samples A to E) were collected from three locations at the eastern foot of the Shinmoedake. Annual rings were cut out from sample E into single-year rings and conducted 14C measurement using accelerator mass spectrometry (AMS). To obtain accurate age for the Kyoho eruption, wiggle-matching technique was applied with computer program OxCal 4.4.2. As a result, the age of the outermost annual ring was found to be 1697-1731 cal AD with a confidence interval of 95.4%, which is consistent with the chronology of ancient documents., 霧島火山群、新燃岳の享保噴火は、古文書の記述にもとづいて西暦1716～1717年であることがわかっている。この時期は、放射性炭素（14C）年代から暦年を較正することが難しいが、14Cウィグル・マッチング法を適用することで正確な年代を得ることができる。本研究では、新燃岳東麓の3ヶ所から樹幹試料（試料A～E）を採取した。そのうちの試料Eから1年単位で年輪を切り出し、加速器質量分析計（AMS）を用いて計8点の14C年代測定を行い、OxCalによるウィグル・マッチングから年代を求めた。その結果、最外年輪（枯死）の年代は、95.4%の信頼区間で1697～1731cal ADとなり、古文書の年代とも矛盾しない。