Yang Rui, Chen Shanqiao, Zhang Xiansheng, Su Rongguo, Zhang Chuansong, Liang Shengkang, Han Xiurong, Wang Xiulin, Li Keqiang
Frontiers Science Center for Deep Ocean Multispheres and Earth System, and Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100, China; College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100, China.
College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100, China.
Mar Pollut Bull. 2021 Aug;169:112551. doi: 10.1016/j.marpolbul.2021.112551. Epub 2021 Jun 16.
Increasing human activities have caused the accumulation of dissolved organic nitrogen (DON) in the ocean, which can alter dominant coastal phytoplankton species. However, insights into DON's effects on marine phytoplankton growth are insufficient compared with those of dissolved inorganic nitrogen (DIN), especially regarding the role of specific DON components. Therefore, in this study, the effects of the hydrophilic (Hic) and low molecular weight (LMW) components of two anthropogenic DON sources on the growth and bioavailable nitrogen uptake of phytoplankton were studied using in situ cultural experiments conducted in Jiaozhou Bay, China. Animal-derived DON from domestic and livestock breeding showed a higher bioavailability compared with that of vegetal DON derived from agricultural sources, with bioavailable component proportions of 76% ± 4% and 66% ± 3%, respectively. Both forms of DON could be absorbed by Skeletonema costatum, stimulating it to become the dominant species in the mesocosm ecosystem; the hydrophilic components of DON contributed approximately 75% of the uptake of DON by S. costatum. The bioavailability of LMW DON was significantly (p < 0.05) lower than that of the Hic DON. The high bioavailability of the Hic DON was mainly associated with its protein-like T1 and T2 components, identified using parallel factor analysis on the excitation-emission-matrix spectra, while the low bioavailability of LMW DON was mainly associated with the humus-like A component. The protein-like T2 components may be directly absorbed by algae, while T1 may be transformed through mineralization and algal absorption. Understanding the impacts of anthropogenic DON and its components on phytoplankton will help improve coastal environmental management. More knowledge of the effect of anthropogenic DON on the phytoplankton community structure in coastal waters should be accumulated in the future.
人类活动的增加导致海洋中溶解有机氮（DON）的积累，这可能会改变沿海主要浮游植物的种类。然而，与溶解无机氮（DIN）相比，关于DON对海洋浮游植物生长影响的见解还不够充分，特别是在特定DON组分的作用方面。因此，在本研究中，利用在中国胶州湾进行的原位培养实验，研究了两种人为DON源的亲水性（Hic）和低分子量（LMW）组分对浮游植物生长和生物可利用氮吸收的影响。与农业来源的植物性DON相比，来自家畜养殖的动物性DON具有更高的生物可利用性，其生物可利用组分比例分别为76%±4%和66%±3%。两种形式的DON都可以被中肋骨条藻吸收，促使其成为中尺度生态系统中的优势物种；DON的亲水性组分对中肋骨条藻吸收DON的贡献约为75%。LMW DON的生物可利用性显著低于Hic DON（p<0.05）。Hic DON的高生物可利用性主要与其在激发-发射-矩阵光谱上通过平行因子分析确定的类蛋白T1和T2组分有关，而LMW DON的低生物可利用性主要与类腐殖质A组分有关。类蛋白T2组分可能被藻类直接吸收，而T1可能通过矿化和藻类吸收进行转化。了解人为DON及其组分对浮游植物的影响将有助于改善沿海环境管理。未来应积累更多关于人为DON对沿海水域浮游植物群落结构影响的知识。
