有機物の分子構成が空間距離とともに予測可能に変化することを発見(New Study Reveals Dissolved Organic Matter Molecular Communities Change Predictably With Spatial Distance)

2025-11-07 中国科学院(CAS)

中国科学院・南京地理与湖沼研究所の研究チームは、大西洋・太平洋・南極海などから得た800件を超える海水サンプルをFT-ICR質量分析で解析し、溶存有機物(DOM)の分子組成が地理的距離や深度に応じて規則的に変化することを明らかにした。水塊間の距離が大きいほどDOM組成の差は拡大する一方、深海や高緯度域では変化が小さく、長寿命分子が残る「化学的同質化」が進むことが示された。また、上層では温度・塩分・炭素供給などの環境要因が主要因であるが、深層では輸送制限など距離に基づくプロセスの影響が強かった。研究チームは、これらの結果が海洋炭素貯留の将来予測に重要であり、温暖化により深海での有機物保存が強まり、炭素シンク機能が増す可能性を指摘している。

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地球規模の海洋における溶存有機物の化学地理学に向けて Toward the Chemogeography of Dissolved Organic Matter in the Global Ocean

Jianjun Wang,Ang Hu,Yifan Cui,Sarah Bercovici,Xiancai Lu,Jay Lennon,Janne Soininen,Yongqin Liu,and Nianzhi Jiao
Environmental Science & Technology  Published: October 20, 2025
DOI:https://doi.org/10.1021/acs.est.5c02477

Abstract

有機物の分子構成が空間距離とともに予測可能に変化することを発見(New Study Reveals Dissolved Organic Matter Molecular Communities Change Predictably With Spatial Distance)

Dissolved organic matter (DOM) comprises a diverse mixture of organic molecules, playing a critical role in marine biogeochemistry and Earth’s climate. However, the ecological patterns and drivers of DOM composition at the global scale and their variation across compound classes remain unclear. Here we quantify the compositional turnover of over 800 DOM samples covering the surface waters to the deep across the global ocean, using distance–decay relationships based on an ultrahigh-resolution mass spectrometry data set. Molecular compositions become increasingly dissimilar to greater geographical distances in both horizontal and vertical dimensions. The observed turnover rates, consistent across biochemically labile and recalcitrant compound classes, progressively decrease toward the deep ocean and high latitudes, indicating a trend of chemohomogenization. The geographical distribution is jointly influenced by horizontal spatial distance, water depth, and physicochemical environments, which suggests that both stochastic and deterministic processes shape the DOM composition homogenization, effectively acting as a “carbon homogenizer”. This study unravels geographical patterns of DOM compositional turnover in the global ocean from an ecological perspective, deepening understanding of the forthcoming biogeochemical changes under global warming.

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