2026-04-07 東京大学,滋賀県琵琶湖環境科学研究センター,国立環境研究所
研究成果の概要（原著論文より改変）。
Q10は温度が10℃上昇したときに有機物の分解速度が何倍になるかを示す値です。陸域起源の古い有機物の方が温度への感受性が高いことが明らかになりました。
＜関連情報＞
- https://www.aori.u-tokyo.ac.jp/research/news/2026/20260407.html
- https://www.sciencedirect.com/science/article/pii/S0043135426004227
温暖化条件下における深層温帯湖での老朽化した堆積有機物の分解：実験的アプローチ Decomposition of Aged Sedimentary Organic Matter in a Deep Temperate Lake Under Warming Conditions: An Experimental Approach
Wataru Nakamura, Yasuhiko T. Yamaguchi, Shish Muhammad Soyaib, Sho Ogasawara, Eiso Inoue, Koichi Shimotori, Yosuke Miyairi, Yusuke Yokoyama
Water Research Available online: 11 March 2026
DOI:https://doi.org/10.1016/j.watres.2026.125740
Highlights
- Radiocarbon traced the age of decomposed sedimentary organic matter
- Aged organic matter decomposed faster at higher water temperatures
- Warming enhances the decomposition of aged allochthonous organic matter
- Land management could help reduce lake hypoxia under global warming
Abstract
Although lakes are major reservoirs for organic matter (OM), global warming may accelerate the decomposition of sedimentary OM. Enhanced OM decomposition under warming intensifies carbon cycling in the biosphere and can lead to ecosystem degradation through deoxygenation. However, it remains unclear whether this temperature-driven increase in decomposition primarily involves modern OM or aged OM. In this study, we applied a novel approach that integrates radiocarbon (Δ14C) analysis with aerobic incubation experiments using undisturbed sediment cores collected from the largest lake in Japan. This approach enabled us to examine directly whether warming accelerates the decomposition of aged OM in aquatic sediments. The age of decomposed OM was estimated by measuring the Δ14C in the dissolved inorganic carbon (DIC) of the overlying water before and after incubation. At the current hypolimnetic temperature of 8°C, the Δ14C value of decomposed OM was −43.6 ± 50.8‰, which is comparable to the surface lake water DIC value. However, the Δ14C values decreased with increasing temperature, reaching −182.3 ± 31.1‰ at 18°C. Monte Carlo simulations estimating the temperature sensitivity of modern OM and aged allochthonous OM indicated that aged allochthonous OM exhibits higher temperature sensitivity. This finding supports the carbon quality to temperature hypothesis. These results suggest that reducing anthropogenic erosion and implementing other land-based management measures could help slow the progression of lake deoxygenation under climate warming.
