Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China.
Fujian Provincial Key Laboratory of Marine Ecological Conservation and Restoration, Xiamen 361005, China.
Environ Sci Technol. 2022 Jun 21;56(12):9112-9122. doi: 10.1021/acs.est.2c01535. Epub 2022 Jun 10.
Under climate change scenarios, the contribution of macroalgae to carbon sequestration has attracted wide attention. As primary producers, macroalgae can release substantial amounts of dissolved organic carbon (DOC) in seawater. However, little is known about the molecular composition and chemical properties of DOC derived from macroalgae and which of them are recalcitrant DOC (RDOC) that can be sequestered for a long time in the ocean. In the most intensive seaweed (kelp) farming area (Sanggou Bay) in China, we found that kelp mariculture not only significantly increased DOC concentration, but also introduced a variety of new DOC molecular species, many of which were sulfur-containing molecules. A long-term DOC degradation experiment revealed that those DOC with strong resistance to microbial degradation, i.e., RDOC, account for approximately 58% of the DOC extracted from kelp mariculture area. About 85% (3587 out of 4224 with different chemical features) of the RDOC molecular species were steadily present throughout the long-term degradation process. 15% (637 out of 4224 with different chemical features) of the RDOC molecular species were likely newly generated by microorganisms after metabolizing macroalgae-derived labile DOC. All these stable RDOC should be included in the blue carbon budgets of seaweed.
在气候变化情景下，大型藻类对碳固存的贡献引起了广泛关注。作为初级生产者，大型藻类可以在海水中释放大量的溶解有机碳（DOC）。然而，人们对来源于大型藻类的 DOC 的分子组成和化学性质知之甚少，也不知道哪些是具有较强抗微生物降解能力的难降解 DOC（RDOC），这些 RDOC 可以在海洋中长时间被封存。在中国最大的海藻（海带）养殖区（桑沟湾），我们发现海带养殖不仅显著增加了 DOC 浓度，而且引入了多种新的 DOC 分子种类，其中许多是含硫分子。一项长期的 DOC 降解实验表明，那些具有较强抗微生物降解能力的 DOC，即 RDOC，占从海带养殖区提取的 DOC 的大约 58%。在长期的降解过程中，约 85%（具有不同化学特征的 4224 种中有 3587 种）的 RDOC 分子种类稳定存在。15%（具有不同化学特征的 4224 种中有 637 种）的 RDOC 分子种类可能是微生物在代谢来源于大型藻类的易降解 DOC 后新生成的。所有这些稳定的 RDOC 都应包含在海藻的蓝色碳预算中。
