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Microbial N 2 O consumption in and above marine N 2 O production hotspots
The ISME Journal ( IF 11.0 ) Pub Date : 2020-12-21 , DOI: 10.1038/s41396-020-00861-2
Xin Sun 1 , Amal Jayakumar 1 , John C Tracey 1 , Elizabeth Wallace 1 , Colette L Kelly 2 , Karen L Casciotti 2 , Bess B Ward 1
Affiliation  

The ocean is a net source of N2O, a potent greenhouse gas and ozone-depleting agent. However, the removal of N2O via microbial N2O consumption is poorly constrained and rate measurements have been restricted to anoxic waters. Here we expand N2O consumption measurements from anoxic zones to the sharp oxygen gradient above them, and experimentally determine kinetic parameters in both oxic and anoxic seawater for the first time. We find that the substrate affinity, O2 tolerance, and community composition of N2O-consuming microbes in oxic waters differ from those in the underlying anoxic layers. Kinetic parameters determined here are used to model in situ N2O production and consumption rates. Estimated in situ rates differ from measured rates, confirming the necessity to consider kinetics when predicting N2O cycling. Microbes from the oxic layer consume N2O under anoxic conditions at a much faster rate than microbes from anoxic zones. These experimental results are in keeping with model results which indicate that N2O consumption likely takes place above the oxygen deficient zone (ODZ). Thus, the dynamic layer with steep O2 and N2O gradients right above the ODZ is a previously ignored potential gatekeeper of N2O and should be accounted for in the marine N2O budget.



中文翻译:

海洋N 2 O生产热点中及以上的微生物N 2 O消耗

海洋是N 2 O的净来源,N 2 O是有效的温室气体和臭氧消耗剂。然而,去除N个2经由微生物N 2 O 2 ö消耗很差约束和速率测量已经局限于缺氧水域。在这里,我们将缺氧区域的N 2 O消耗量测量范围扩展到其上方的尖锐的氧气梯度,并首次通过实验确定了含氧和缺氧海水中的动力学参数。我们发现,在含氧水中,底物亲和力,O 2耐受性和消耗N 2 O的微生物的群落组成不同于下面的缺氧层中的微生物。此处确定的动力学参数用于原位N 2建模O生产和消费率。估计的原位速率与测得的速率不同,这证实了预测N 2 O循环时必须考虑动力学的必要性。来自氧化层的微生物在缺氧条件下消耗N 2 O的速度比来自缺氧区域的微生物快得多。这些实验结果与模型结果吻合,模型结果表明N 2 O消耗可能发生在缺氧区(ODZ)上方。因此,具有陡峭澳动态层2和N 2 ö梯度权利ODZ以上为N的先前忽略的电势关守2 O和应在海洋N为占2 ö预算。

更新日期:2020-12-21
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