Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, 238 Songling Road, Qingdao 266100, PR China.
Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, 238 Songling Road, Qingdao 266100, PR China; National Marine Hazard Mitigation Service, Beijing 100194, China.
Sci Total Environ. 2024 Dec 1;954:176360. doi: 10.1016/j.scitotenv.2024.176360. Epub 2024 Sep 18.
The biogeochemical processes of amino acids in the Southern Yellow Sea (SYS) have become more dynamic under the influence of the world's largest-scale green tide. The potential relationship between amino acids and green tides has not been effectively assessed, despite its critical importance for exploring dissolved organic matter (DOM) cycling processes in marginal seas. In this study, three cruises were conducted to analyze the concentrations and compositions of total hydrolyzed amino acids (THAAs) in the SYS during the spring, summer, and autumn of 2019. The bioavailability potential of DOM was evaluated using the degradation index (DI) and THAA nitrogen normalized yield (THAA (%DON)) (DON as dissolved organic nitrogen). The variation dynamics of amino acid indicators during different stages of green tide were further explored. The results showed that the THAA concentrations and DOM bioavailability in the SYS were considerably influenced by biological processes. The THAA concentrations (0.96 ± 0.34 μmol L) exhibited the lowest mean values in the summer, while the DI values (0.106 ± 0.461) and mean THAA (%DON) values (18.20 ± 6.58 %) were the highest during this season. The distribution of amino acid indicators in the summer (the late-tide stage) was regulated by the green tide mechanism, and kept pace with the green tide floating region. In comparison with the waters in south of 35° N, the THAA concentrations and DI values experienced significant seasonal variations (p < 0.05) in north of 35° N, with the highest DI values (1.217) observed in the green tide aggregation area. This indicates the transformation of nutrient sources for Ulva prolifera in the late-tide stage and its impact on DOM bioavailability. Thus, as a potential feedback indicator of green tides, the study of amino acids is meaningful for understanding the occurrence of green tides and the source-sink pattern of organic nitrogen.
在世界上最大规模的绿潮影响下，南黄海（SYS）的氨基酸生物地球化学过程变得更加活跃。尽管评估氨基酸与绿潮之间的潜在关系对于探索边缘海溶解有机物质（DOM）循环过程至关重要，但尚未对此进行有效评估。在这项研究中，于 2019 年春季、夏季和秋季进行了三次巡航，以分析 SYS 中总水解氨基酸（THAA）的浓度和组成。使用降解指数（DI）和 THAA 氮归一化产量（THAA（% DON））（DON 为溶解有机氮）评估 DOM 的生物利用潜力。进一步探讨了绿潮不同阶段氨基酸指标的变化动态。结果表明，SYS 中的 THAA 浓度和 DOM 生物利用度受生物过程的显著影响。THAA 浓度（0.96±0.34μmol L）在夏季的平均值最低，而 DI 值（0.106±0.461）和平均 THAA（% DON）值（18.20±6.58%）在该季节最高。夏季（晚潮阶段）氨基酸指标的分布受绿潮机制的调节，并与绿潮漂浮区保持同步。与北纬 35°以南的水域相比，北纬 35°以北的 THAA 浓度和 DI 值经历了显著的季节性变化（p<0.05），在绿潮聚集区观察到最高的 DI 值（1.217）。这表明在晚潮阶段，Ulvaprolifera 的营养源发生了转变，以及其对 DOM 生物利用度的影响。因此，作为绿潮的潜在反馈指标，氨基酸的研究对于理解绿潮的发生以及有机氮的源汇格局具有重要意义。
