Contrasting impact of elevated atmospheric CO2 on nitrogen cycle in eutrophic water with or without Eichhornia crassipes (Mart.) Solms
Contrasting impact of elevated atmospheric CO2 on nitrogen cycle in eutrophic water with or without Eichhornia crassipes (Mart.) Solms
复制标题
大气二氧化碳浓度升高对含有或不含凤眼莲（Mart.） Solms 的富营养化水体中氮循环的影响对比
DOI：
10.1016/j.scitotenv.2019.02.224
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发表时间：
2019
影响因子：
9.8
通讯作者：
Yan Shaohua
中科院分区：
文献类型：
--
作者：
Shi Man;Li Jiangye;Zhang Weiguo;Zhou Qi;Niu Yuhan;Zhang Zhenhua;Gao Yan;Yan Shaohua
大气CO2浓度升高是一种必然趋势，通过微生物活动对水生态系统中相互关联的碳氮循环产生重大影响。富营养化已成为世界范围内内陆沃茨的一种常见营养状态，但CO2浓度升高如何影响富营养化水体中的N循环，以及植被恢复如何减少N2 O排放仍是未知数。我们进行了实验，以调查环境和升高的大气CO2（a[CO2]，e[CO2]; 400，800 μmol chairmol −1）的影响，有和没有浮动水生植物，凤眼莲crassipes（Mart.）索尔姆斯，用15 N示踪法研究富营养化水体中的N转化。e[CO2]对硝化作用有一定的抑制作用，主要是由于藻类与硝化菌之间对溶解性无机碳的竞争。e[CO2]促进了富营养化水体的反硝化作用和N2 O排放，而植物却不生长，导致温室效应加剧，形成恶性循环。然而，生长的水生植物，凤眼莲，略有促进硝化作用，但减少了N2 O排放量从富营养化水体中的e[CO2]条件下，从而削弱了负效应[CO2]对N2 O排放。在本试验中，氮的转化除受e[CO2]和植物存在的影响外，还受pH、DO和藻类密度等多种因素的影响。pH值可以通过藻类的光合作用和呼吸作用进行调节，缓解由e[CO2]引起的水体酸化，从而为硝化和反硝化微生物提供一个合适的pH值范围。夜间藻类呼吸可以消耗DO并增加水中反硝化功能基因（nirK、nosZ）的丰度，这也被认为是影响反硝化和N2 O排放的关键因素。本研究阐明了由e[CO2]引起的温室效应是如何介导水生生态系统中氮的地球化学循环的，以及植被恢复是如何减轻温室气体排放的。
The elevation of atmospheric CO2is an inevitable trend that would lead to significant impact on the interrelated carbon and nitrogen cycles through microbial activities in the aquatic ecosystem. Eutrophication has become a common trophic state of inland waters throughout the world, but how the elevated CO2affects N cycles in such eutrophic water with algal bloom, and how vegetative restoration helps to mitigate N2O emission remains unknown. We conducted the experiments to investigate the effects of ambient and elevated atmospheric CO2(a[CO2], e[CO2]; 400, 800 μmol﹒mol−1) with and without the floating aquatic plant,Eichhornia crassipes(Mart.) Solms, on N-transformation in eutrophic water using the15N tracer method. The nitrification could be slightly inhibited by e[CO2], due mainly to the competition for dissolved inorganic carbon between algae and nitrifiers. The e[CO2] promoted denitrification and N2O emissions from eutrophic water without growth of plants, leading to aggravation of greenhouse effect and forming a vicious cycle. However, growth of the aquatic plant,Eichhornia crassipes, slightly promoted nitrification, but reduced N2O emissions from eutrophic water under e[CO2] conditions, thereby attenuating the negative effect of e[CO2] on N2O emissions. In the experiment, the N transformation was influenced by many factors such as pH, DO and algae density, except e[CO2] and plant presence. The pH could be regulated through diurnal photosynthesis and respiration of algae and mitigated the acidification of water caused by e[CO2], leading to an appropriate pH range for both nitrifying and denitrifying microbes. Algal respiration at night could consume DO and enhance abundance of denitrifying functional genes (nirK,nosZ) in water, which was also supposed to be a critical factor affecting denitrification and N2O emissions. This study clarifies how the greenhouse effect caused by e[CO2] mediates N biogeochemical cycle in the aquatic ecosystem, and how vegetative restoration mitigates greenhouse gas emission.