Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100, China; Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China.
Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100, China.
Sci Total Environ. 2022 Sep 10;838(Pt 1):155878. doi: 10.1016/j.scitotenv.2022.155878. Epub 2022 May 14.
To explore the spatial and temporal distributions of dissolved organic matter (DOM) affected by Ulva prolifera bloom and the regulation of DOM released by the addition of nitrate (NO-N) nutrients, the variation in DOM was analyzed by three cruises in the coastal waters of the southern Yellow Sea (SYS) off Qingdao during a 2018 U. prolifera bloom. A mesocosm experiment was conducted during the decay of U. prolifera. The U. prolifera bloom resulted in higher concentrations of the bulk DOM except for total dissolved amino acids (TDAA), compared with levels recorded during non-bloom periods. Three different fluorescent substances of chromophoric dissolved organic matter (CDOM) were identified, which were also affected by the bloom. Concentrations of total dissolved carbohydrates (TCHO), monosaccharides (MCHO), and polysaccharides (PCHO) peaked during the late bloom, with average levels of 49.78 ± 9.73, 14.23 ± 3.32, and 35.55 ± 9.19 μmol C L, respectively, accompanied by an increase of DOC, indicating release of DOM with U. prolifera decay. In contrast, the concentrations of CDOM and TDAA declined during the late bloom, with averages of 0.10 ± 0.10 m and 1.16 ± 0.82 μmol L, suggesting that the yields of CDOM and TDAA were regulated by the U. prolifera bloom and other mechanism. These findings were confirmed by the mesocosm experiment. DOM production was obviously improved by NO-N addition except for TDAA and CDOM. The release of protein-like CDOM was primarily regulated by NO-N nutrients, however, it was not obvious with humic-like CDOM. Our findings provide evidence supporting the role of U. prolifera blooms in the coastal DOM pool and its significant effect on the marine carbon cycle.
为了探究受浒苔（Ulva prolifera）藻华影响的溶解有机物（DOM）的时空分布及其调控机制，我们分析了 2018 年青岛南部黄海（SYS）海域浒苔藻华期间 3 次航次的 DOM 变化。在浒苔腐烂过程中进行了中尺度实验。与非藻华期相比，浒苔藻华期间 DOM 总体浓度较高，除总溶解氨基酸（TDAA）外，其他 DOM 浓度均较高。还鉴定出三种不同的色溶有机物（CDOM）荧光物质，这些物质也受到藻华的影响。总溶解碳水化合物（TCHO）、单糖（MCHO）和多糖（PCHO）的浓度在藻华后期达到峰值，平均浓度分别为 49.78 ± 9.73、14.23 ± 3.32 和 35.55 ± 9.19 μmol C L，伴随着 DOC 的增加，表明 DOM 随着浒苔的腐烂而释放。相比之下，CDOM 和 TDAA 的浓度在藻华后期下降，平均值分别为 0.10 ± 0.10 m 和 1.16 ± 0.82 μmol L，这表明 CDOM 和 TDAA 的产量受到浒苔藻华的调控以及其他机制的影响。中尺度实验证实了这一发现。除 TDAA 和 CDOM 外，NO-N 加标明显提高了 DOM 的产生。蛋白质样 CDOM 的释放主要受 NO-N 营养物质调控，但对腐殖质样 CDOM 的调控作用不明显。我们的研究结果为浒苔藻华在沿海 DOM 库中的作用及其对海洋碳循环的显著影响提供了证据支持。
