Mo Shansheng, Liu Zhongli, Hao Yuanhao, Hertkorn Norbert, Wang Hanzhe, Zhang Chenyang, Korshin Gregory, Ni Jinren, Yan Mingquan
College of Environmental Sciences and Engineering, Peking University, Beijing, 100871, China.
Institute of Ocean Research, Peking University, Beijing, 100871, China.
Nat Commun. 2025 Jun 4;16(1):5202. doi: 10.1038/s41467-025-60510-0.
Understanding the dynamics of marine dissolved organic carbon (DOC) is essential for predicting its role in carbon cycling and its response to climate change. Here, we unveil molecular transformations of marine chromophoric dissolved organic matter (CDOM) across the global ocean using Ultraviolet-visible spectroscopy. Significant variability in CDOM composition within the epi- and mesopelagic layers ( < 1000 m) correlates with physicochemical parameters, driven by irradiation, primary production, biological activity, transport, and riverine inputs. In the bathypelagic layer (1000-5000 m), up to 18.2% of highly conjugated molecules transform into low-molecular-weight CDOM, despite stable DOC concentrations. This dynamic process sustains biomass production and respiration in deep ocean, contributing a carbon flux of 3-24 Pg C yr-up to an order of magnitude more than the fast-sinking particulate organic carbon flux. Our findings offer insights into the molecular transformation of deep-ocean DOM and underscore the need to reassess the bathypelagic DOC pool's role in the global carbon cycle.
了解海洋溶解有机碳（DOC）的动态变化对于预测其在碳循环中的作用及其对气候变化的响应至关重要。在此，我们利用紫外可见光谱揭示了全球海洋中海洋发色溶解有机物（CDOM）的分子转化。上层和中层（<1000米）内CDOM组成的显著变化与物理化学参数相关，这是由辐射、初级生产、生物活动、运输和河流输入驱动的。在深层（1000 - 5000米），尽管DOC浓度稳定，但高达18.2%的高度共轭分子会转化为低分子量CDOM。这一动态过程维持了深海中的生物量生产和呼吸作用，贡献了3 - 24Pg C yr-1的碳通量，比快速下沉的颗粒有机碳通量高出一个数量级。我们的研究结果为深海DOM的分子转化提供了见解，并强调了重新评估深层DOC库在全球碳循环中作用的必要性。
