The secretion of organics by living Microcystis under the dark/anoxic condition and its enhancing effect on nitrate removal
The secretion of organics by living Microcystis under the dark/anoxic condition and its enhancing effect on nitrate removal
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暗/缺氧条件下活体微囊藻的有机物分泌及其对硝酸盐去除的增强作用
DOI：
10.1016/j.chemosphere.2017.12.197
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发表时间：
2018-04-01
期刊：
影响因子：
8.8
通讯作者：
Davis, Timothy Walter
中科院分区：
文献类型：
--
作者：
Chen, Xuechu;Huang, Yingying;Davis, Timothy Walter
近年来的研究表明，藻类分解产生颗粒和溶解性有机碳（DOC），可以增强富营养化湖泊的反硝化作用。然而，活体蓝细菌对富营养化湖泊氮循环的影响仍然是一个未知的问题。本研究探索了一种新的硝酸盐去除机制，这是由活的微囊藻驱动。结果表明，微囊藻对沉积物-水界面硝酸盐的去除有显著的促进作用，其去除率为0.54 d（-1），是未投加微囊藻处理的2.57倍。叶绿素a和Fv/Fm的测定证实了微囊藻对黑暗/缺氧条件的耐受性，恢复实验表明微囊藻在黑暗/缺氧条件下至少能存活7 d。同时，活微囊藻分泌的DOC达到4.55mgC mg（-1）Chl a.这些分泌物是可生物降解的亲水性的，并含有碳水化合物和蛋白质。研究表明，水华期间，下沉的微囊藻细胞可以直接提供DOC作为碳源，从而增强沉积物-水界面的反硝化作用，在研究水生生态系统氮循环时应考虑活体蓝藻与硝酸盐永久去除的相互关系。(C)2018爱思唯尔有限公司版权所有。
Recent studies indicated that the algal decomposition produces particulate and dissolved organic carbon (DOC), and can enhance denitrification in eutrophic lakes. However, the effects of the living cyanobacteria on nitrogen cycling in eutrophic lakes were still an unknown question. This study explores a new underlying mechanism of nitrate removal which is driven by living Microcystis. The results suggested that living Microcystis significantly enhanced the nitrate removal at sediment-water interface, with a nitrate removal rate of 0.54 d(-1), which was 2.57 times higher than the nitrate removal rate in the treatment without the addition of Microcystis. Measurements of Chl a and Fv/Fm confirmed that Microcystis was tolerant to the dark/anoxic condition, and the recovery experiments suggested that Microcystis could survive under such stress conditions for at least seven days. Meanwhile, DOC secreted by living Microcystis reached to 4.55 mg C mg(-1) Chl a. These secretions were biodegradable hydrophilic and contained carbohydrates and proteins. Our study indicated that during blooms, sinking Microcystis cells could directly provide DOC as carbon source, then consequently enhanced the denitrification at sediment water interface, and the interactive relationship between living cyanobacteria and permanent nitrate removal should be taken into account while studying nitrogen cycling in aquatic ecosystem. (C) 2018 Elsevier Ltd. All rights reserved.