Underestimated input of terrestrial dissolved organic carbon to the ocean
Abstract
The contribution of terrestrial dissolved organic matter (DOM) to the ocean has been an enigma for decades. Tracking terrestrial DOM in the ocean has proven challenging due to factors such as the instability of terrestrial biomarkers, indistinguishable carbon isotopes from biogeochemical fractionation, and similar chemical composition between terrestrial and oceanic DOM. Here, we show that the terrestrial contribution to oceanic organic carbon pools is 1.7 to 2.5 times higher than previously assumed, highlighting the need to adjust global carbon cycle models. We derive these estimates by bridging high-performance liquid chromatography with ultra-high resolution mass spectrometry to investigate the presence of terrestrial molecules that are transported from rivers to the ocean and estimate their contribution to oceanic DOM. We identified 269 molecular formulae (MF) that are likely transported from land to the ocean. These formulae exhibited resistance to biological and photochemical degradation in incubation experiments, and were widely distributed in global rivers, marginal seas, and open oceans, suggesting that they are ubiquitous in inland and ocean waters and have a similar source. By relating the abundances of terrestrially derived MF to dissolved organic carbon concentrations, and radiocarbon measurements, we estimated that 16.7 to 25.0% of oceanic DOM is likely derived from rivers.
Article Details
Journal Info
Proceedings of the National Academy of Sciences
National Academy of Sciences
Authors (15)
Yuanbi Yi
Department of Ocean Science and Center for Ocean Research in Hong Kong and Macau, The Hong Kong University of Science and Technology
Andrew J. Tanentzap
Chen He
State Key Laboratory of Heavy Oil Processing, College of Chemical Engineering and Environment, China University of Petroleum
Julian Merder
Department of Global Ecology, Carnegie Institution for Science
Helena Osterholz
Marine Chemistry, Leibniz Institute for Baltic Sea Research Warnemünde
Hongyan Bao
State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University
Jeffrey A. Hawkes
Department of Chemistry for Life Sciences, Uppsala University
Ruanhong Cai
Department of Ocean Science and Center for Ocean Research in Hong Kong and Macau, The Hong Kong University of Science and Technology
Si-Liang Li
Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University
Quan Shi
State Key Laboratory of Heavy Oil Processing, College of Chemical Engineering and Environment, China University of Petroleum
Sheng Xu
Chuanlun Zhang
Department of Ocean Science and Engineering, Shenzhen Key Laboratory of Marine Archaea Geo-Omics, Southern University of Science and Technology
Cong-Qiang Liu
Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University
Meixun Zhao
Frontiers Science Center for Deep Ocean Multispheres and Earth System of the Ministry of Education, Institute for Advanced Ocean Study, Ocean University of China
Ding He
Department of Ocean Science and Center for Ocean Research in Hong Kong and Macau, The Hong Kong University of Science and Technology