Nitrous oxide and nitrogen gas production in the Arabian Sea - a process and community based study

阿拉伯海的一氧化二氮和氮气生产——基于过程和社区的研究

基本信息

批准号：
NE/E01559X/1
负责人：
Mark Trimmer
金额：
$ 54.51万
依托单位：
Queen Mary University of London
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2011
资助国家：
英国
起止时间：
2011 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FE01559X%2F1
关键词：
Nitrous oxide nitrogen gas production

项目摘要

The element nitrogen (N) is key to life on Earth and it is continually being cycled between the atmosphere, biomass (animals, plants, microbes) and back to the atmosphere following death and decay. At the centre of this N cycling, on the land and in the sea, are a wide variety of microscopic organisms known as bacteria. In the atmosphere N exists largely as N2 gas but also in much smaller amounts as nitrous oxide (N2O) which is a potent greenhouse gas. Processes which remove N, as N2, can regulate the growth of plants and, indirectly, the balance of carbon dioxide (CO2) in the atmosphere and, hence, affect climate. Large areas of the global ocean are fully oxygenated or 'saturated' with oxygen (O2) but some parts are not. For example, the Black Sea completely lacks any O2 below 90 m and others such as the Benguela upwelling off south western Africa are also devoid of O2 / both these areas have oxygen minimum zones or OMZ. It is these O2 'starved' regions or OMZ that are significant for both N removal and N2O production in the global ocean. Our interest lies in that of the OMZ of the Arabian Sea which, due to its large size (that of France and Germany combined), plays a significant role in global N cycling / responsible for 20 % of N2O production and 30 % of N removal in the global ocean. While the significance of the Arabian Sea in the global N cycle is known, the metabolisms responsible for N2 and N2O production were, and are still in part, unclear. Recently, by looking a bit closer and in conjunction with N tracers (15N isotopes), we were the first to actually measure N2O production in the central Arabian Sea. Further, we demonstrated that most (>95 %) of the N2O produced could be explained simply by one pathway i.e. the metabolism of nitrite (NO2-) to N2O in the absence of O2. In addition, we measured N removal via two known paths of N2 production e.g. N2 from denitrification and N2 from anaerobic ammonium oxidation (anammox). However, a substantial portion of the N2 is coming from somewhere else and we have evidence that this extra new path of N2 production is directly coupled to the metabolism of decaying biomass. However, it is not as simple as this. One pathway of N2O formation requires some complexity to generate the high and low concentrations of N2O characteristic of the OMZ in the central Arabian Sea. Again, our 15N tracers uncovered some of this by showing that the ratio of N2 to N2O production during the metabolism of NO2- (NO2- to NO to N2O to N2) is not fixed and appears to be 'flexible'. For example, where water column N2O concentration is high, we measured a low ratio of N2 to N2O production from NO2- and vice versa where water column N2O concentration was low. Although this 'flexible' ratio explains the majority of N2O and helps redefine our understanding of N2O production in oxygen minimum zones / why this ratio should change is unknown. In this project we aim to characterise the water column at selected sites in the central Arabian Sea in terms of, for example, N2O, O2 and the bacteria driving the N-cycle. We will experimentally manipulate contrasting waters to test if the ratio of N2 to N2O production is 'fixed' or 'flexible', screen for N2 production coupled to organic matter and analyse the active bacteria involved in the metabolism of these gases by using molecular or 'genetic' techniques. A better understanding of the key processes and bacteria involved in these complex metabolisms in such an important area as the Arabian Sea should help the scientific community build better predictive climate models.

氮 (N) 元素是地球上生命的关键，它不断在大气、生物质（动物、植物、微生物）之间循环，并在死亡和腐烂后返回大气。在陆地和海洋中，氮循环的中心是各种各样的微生物，即细菌。大气中的氮主要以氮气形式存在，但也以一氧化二氮 (N2O) 的形式存在，而一氧化二氮 (N2O) 是一种强效温室气体。以 N2 形式去除氮的过程可以调节植物的生长，并间接调节大气中二氧化碳 (CO2) 的平衡，从而影响气候。全球海洋的大片区域已完全充氧或被氧气 (O2)“饱和”，但有些部分则不然。例如，黑海 90 m 以下完全缺乏氧气，其他地区（例如非洲西南部的本格拉上升流）也缺乏氧气/这两个地区都有氧气最低区或 OMZ。正是这些氧气“饥饿”区域或 OMZ 对于全球海洋中的 N 去除和 N2O 产生具有重要意义。我们感兴趣的是阿拉伯海的 OMZ，由于其规模较大（法国和德国的总和），它在全球氮循环中发挥着重要作用/负责 20% 的 N2O 生产和 30% 的氮去除在全球海洋中。虽然阿拉伯海在全球氮循环中的重要性是众所周知的，但负责产生 N2 和 N2O 的新陈代谢仍然部分不清楚。最近，通过更仔细地观察并结合 N 示踪剂（15N 同位素），我们是第一个实际测量阿拉伯海中部 N2O 产量的人。此外，我们证明大部分（>95%）产生的 N2O 可以简单地用一种途径来解释，即在没有 O2 的情况下亚硝酸盐 (NO2-) 代谢为 N2O。此外，我们还测量了通过两条已知的 N2 生产路径（例如：来自反硝化的 N2 和来自厌氧氨氧化（anammox）的 N2。然而，很大一部分氮气来自其他地方，我们有证据表明，这条额外的新氮气生产途径与腐烂生物质的新陈代谢直接相关。然而，事情并不这么简单。 N2O 形成的一种途径需要一定的复杂性才能产生阿拉伯海中部 OMZ 特有的高浓度和低浓度 N2O。我们的 15N 示踪剂再次揭示了其中的一些情况，显示 NO2- 代谢过程中 N2 与 N2O 产生的比率（NO2- 到 NO 到 N2O 到 N2）不是固定的，并且似乎是“灵活的”。例如，当水柱 N2O 浓度较高时，我们测量到 NO2- 产生的 N2 与 N2O 的比率较低，反之亦然，当水柱 N2O 浓度较低时。尽管这种“灵活”的比例解释了大部分 N2O 的产生，并有助于重新定义我们对氧气最低区 N2O 产生的理解，但为什么这个比例应该改变尚不清楚。在这个项目中，我们的目标是描述阿拉伯海中部选定地点的水柱特征，例如 N2O、O2 和驱动氮循环的细菌。我们将通过实验操作对比水来测试 N2 与 N2O 产生的比例是“固定”还是“灵活”，筛选与有机物相关的 N2 产生，并通过使用分子或“分析”来分析参与这些气体代谢的活性细菌。遗传'技术。更好地了解阿拉伯海这样一个重要地区的复杂新陈代谢的关键过程和细菌，应该有助于科学界建立更好的预测气候模型。

项目成果

期刊论文数量（5）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Nitrous oxide as a function of oxygen and archaeal gene abundance in the North Pacific.

DOI：
10.1038/ncomms13451
发表时间：
2016-12-01
期刊：
NATURE COMMUNICATIONS
影响因子：
16.6
作者：
Trimmer, Mark;Chronopoulou, Panagiota-Myrsini;Maanoja, Susanna T.;Upstill-Goddard, Robert C.;Kitidis, Vassilis;Purdy, Kevin J.
通讯作者：
Purdy, Kevin J.

Remineralization of particulate organic carbon in an ocean oxygen minimum zone.