A new dynamic for Phosphorus in RIverbed Nitrogen Cycling - PRINCe

RIverbed 氮循环中磷的新动态 - PRINCe

• 批准号: NE/P011624/1
• 负责人: Boyd McKew
• 金额: $ 42.4万
• 依托单位: University of Essex
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2017
• 资助国家: 英国
• 起止时间: 2017 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FP011624%2F1
• 关键词: new; dynamic; Phosphorus; RIverbed; Nitrogen

Humans have learnt how to manipulate and harness the elements that sustain life on Earth (Carbon - C; nitrogen - N and phosphorus - P). Indeed, we have become so skilled at this that we have practically doubled the amount of fixed nitrogen (N) available to us to grow crops and, with current farming practices, we simply couldn't sustain the human population without it. This harnessing of N has come at a considerable cost to the environment, however, particularly rivers, estuaries and coastal seas, where it affects their quality and value as ecosystems. For example, high N loads can enter rivers as run-off from agricultural land to cause algal blooms, oxygen depletion and their general deterioration. Riverbeds can naturally reduce these high N loads and thus provide an important "ecosystem service" globally, not only for the rivers - but also for the estuaries and coastal seas into which they drain. Consequently, riverbeds are recognised hotspots of N cycling, converting ~40% of N-runoff back to inert, atmospheric nitrogen gas (N2) in a process known as denitrification. Here, specialized bacteria (denitrifying bacteria), living in oxygen-free zones of the riverbed, convert N as nitrate, via a number of intermediates, to N2 gas. The nitrate for this process is provided either from terrestrial run-off or from another microbial driven process called nitrification. Nitrification is only active in well-oxygenated environments and converts ammonia to nitrate - via nitrite. This coupling between nitrification and denitrification was, until recently, the consensus view on how fixed N was removed in rivers. However, our findings suggest that another process may also be essential for this overall ecosystem service.This alternative process to denitrification in N2 production is known as anaerobic ammonium oxidation (anammox), whereby nitrite and ammonia are converted more simply to N2 gas. Up until recently, anammox was not considered to be of any importance in well oxygenated rivers. However, our work has already shown that anammox is of greatest significance in permeable riverbeds (gravel and sand-beds), contributing up to 58% of N2 production, and compared to only 7% in impermeable clays. This is very surprising and completely at odds with present knowledge on the function of rivers and factors governing and regulating anammox activity in nature. We can also now demonstrate that the fraction of ammonium that is either fully nitrified to nitrate (ecosystem N conservation) or oxidised to N2 gas (ecosystem N loss) appears to be dependent on phosphorus (P). Where P is higher, more ammonium is recovered as nitrate and where P is scarce a greater fraction is lost as N2 gas - particularly through anammox.Finally, whereas we know that both human derived N and P contribute to the global problem of eutrophication - basically too much plant growth in water - here we are proposing a new antagonistic effect of P and ask whether: 1. By supporting complete nitrification of ammonium to nitrate, does the availability of P actively help to conserve bioavailable N over its removal to inert N2 gas? 2. Could management schemes aimed at removing P from freshwater have both direct and indirect benefits, whereby lowering P actively promotes the removal of fixed N? Currently the role of P in relation to the removal or conservation of fixed N is unknown and that is the main thrust of our new, 'blue-skies' proposal. These permeable riverbeds function as natural biocatalytic filters, hosting microbial communities that, in concert, efficiently remove fixed N. To fully understand and exploit this we need to ask who the main microbes are, how they interact and what regulates their activity? These are the key questions we wish to address in our project. Such understanding could be translated into more efficient wastewater treatment processes and the development of operational best practice for better process control and general management of water resources.

人类已经学会了如何操纵和利用维持地球生命的元素（碳- C;氮- N和磷- P）。事实上，我们已经变得如此熟练，以至于我们可以用来种植作物的固定氮（N）的数量几乎翻了一番，而按照目前的农业实践，没有它我们根本无法维持人类人口。这种氮的利用对环境造成了相当大的代价，但是，特别是河流，河口和沿海海洋，它影响了它们作为生态系统的质量和价值。例如，高氮负荷可作为农田径流进入河流，导致藻类大量繁殖、氧气耗尽和总体恶化。河床可以自然地减少这些高氮负荷，从而在全球范围内提供重要的“生态系统服务”，不仅为河流-而且为河口和沿海海域，他们流入。因此，河床被认为是氮循环的热点，在一个被称为反硝化的过程中，约40%的氮径流转化为惰性的大气氮气（N2）。在这里，生活在河床无氧区的特殊细菌（分解细菌）通过许多中间体将N转化为硝酸盐，转化为N2气体。这一过程中的硝酸盐来自陆地径流或另一种称为硝化作用的微生物驱动过程。硝化作用仅在氧合良好的环境中活跃，并通过亚硝酸盐将氨转化为硝酸盐。直到最近，硝化和反硝化之间的耦合是关于固定氮在河流中如何去除的共识。然而，我们的研究结果表明，另一个过程也可能是必不可少的整体生态系统service.This替代过程中的氮生产反硝化被称为厌氧氨氧化（anammox），其中亚硝酸盐和氨更简单地转化为N2气体。直到最近，厌氧氨氧化物被认为是没有任何重要性，在良好的含氧河流。然而，我们的工作已经表明，厌氧氨氧化是最重要的渗透性河床（砾石和砂床），贡献了高达58%的N2生产，相比之下，只有7%在不渗透的粘土。这是非常令人惊讶的，完全不符合目前对河流功能和自然界中控制和调节厌氧氨氧化物活动的因素的认识。我们现在还可以证明，无论是完全硝化成硝酸盐（生态系统氮保护）或氧化成N2气体（生态系统氮损失）的铵的部分似乎取决于磷（P）。在P较高的地方，更多的铵被回收为硝酸盐，在P稀缺的地方，更大的部分是作为N2气体损失的-特别是通过厌氧氨氧化。最后，虽然我们知道，人类来源的N和P有助于全球性的富营养化问题-基本上太多的植物生长在水中-在这里，我们提出了一个新的拮抗作用的P，并问是否：1。通过支持铵到硝酸盐的完全硝化，P的可用性是否积极地帮助保存生物可利用的N，而不是将其去除为惰性N2气体？2.旨在从淡水中去除磷的管理计划是否具有直接和间接的好处，从而降低磷积极促进固定氮的去除？目前，P在去除或保护固定N方面的作用尚不清楚，这是我们新的“蓝天”建议的主要内容。这些可渗透的河床起到天然生物催化过滤器的作用，容纳微生物群落，共同有效地去除固定N。为了充分理解和利用这一点，我们需要问谁是主要的微生物，它们如何相互作用以及是什么调节它们的活动？这些是我们希望在项目中解决的关键问题。这种理解可以转化为更有效的废水处理工艺和开发最佳操作实践，以实现更好的过程控制和水资源的总体管理。

项目成果

Hydrological properties predict the composition of microbial communities cycling methane and nitrogen in rivers.

• DOI: 10.1038/s43705-022-00087-7
• 发表时间: 2022-01-21
• 期刊: ISME COMMUNICATIONS
• 作者: Clark, Dave R.;Mckew, Boyd A.;Binley, Andrew;Heppell, Catherine M.;Whitby, Corinne;Trimmer, Mark
• 通讯作者: Trimmer, Mark

Mineralization and nitrification: Archaea dominate ammonia-oxidising communities in grassland soils

• DOI: 10.1016/j.soilbio.2020.107725
• 发表时间: 2020-04-01
• 期刊: SOIL BIOLOGY & BIOCHEMISTRY
• 影响因子: 9.7
• 作者: Clark, Dave R.;McKew, Boyd A.;Whitby, Corinne
• 通讯作者: Whitby, Corinne

Relationships between nitrogen cycling microbial community abundance and composition reveal the indirect effect of soil pH on oak decline.

• DOI: 10.1038/s41396-020-00801-0
• 发表时间: 2021-03
• 期刊: The ISME journal
• 作者: Scarlett K;Denman S;Clark DR;Forster J;Vanguelova E;Brown N;Whitby C
• 通讯作者: Whitby C

Extremely halophilic archaeal communities are resilient to short-term entombment in halite.

• DOI: 10.1111/1462-2920.14913
• 发表时间: 2021-07
• 期刊: Environmental microbiology
• 影响因子: 5.1
• 作者: Huby TJC;Clark DR;McKew BA;McGenity TJ
• 通讯作者: McGenity TJ