The contribution of ammonification to N2O emissions from soils

该项目将研究一种名为氨化的细菌过程在土壤中一氧化二氮(N2O)排放中的意义。N2O可能是最广为人知的麻醉剂“笑气”。然而，从全球范围来看，N2O的排放可不是闹着玩的，因为它是一种强有力的温室气体，可以在大气中持续数百年。这种气体的全球排放量每年都在增加，其中很大一部分来自生物来源。这非常令人担忧，因为这种气体参与了全球变暖和平流层臭氧的破坏。因此，了解细菌氨化过程中N2O释放的酶过程、这些过程的调节以及负责N2O释放的微生物的性质是至关重要的。然后，就有可能提出对土壤-植物系统的适当管理，以减少排放并改进现有的模式。这一点很重要，因为适当的氨化缓解策略可能不同于另一种称为反硝化的细菌过程，后者也可能导致N2O排放。在这里，我们将涵盖从产生气体的纯化酶到土壤中含有这些酶的复杂群落的氨化器中N2O排放的整体情况。我们将使用酶分析和稳定同位素技术来确定这一过程中的氨化速率和N2O的产生，并将使用分子技术来研究土壤中的氨化种群。

This project will investigate the significance of a bacterial process called ammonification in the emmission of nitrous oxide (N2O) from soils. N2O is perhaps most commonly known as the anaesthetic 'laughing gas'. However in global terms emissions of N2O is no laughing matter as it is a potent green house gas that can persist in the atmosphere for hundreds of years. The global emmissions of this gas are rising yearly and much of this is from biological sources. This is of great concern due to the involvement of this gas in global warming and the destruction of stratospheric ozone. Thus it is vital to understand the enzymatic processes that underlie N2O release, the regulation of these processes and the nature of the microorganisms responsible for the nitrous oxide release during bacterial ammonification. It will then be possible to propose appropriate management of the soil-plant system to mitigate emissions and to improve existing models. This is important as appropriate mitigation strategies for ammonification are likely to differ from another bacterial process called denitrification that can also lead to N2O emmission. Here we will encompass the whole picture of N2O emission in ammonifiers from the purified enzymes that produce the gas to complex communities that harbour these enzymes in soil. We will use enzyme analysis and stable isotope techniques to determine ammonification rates and N2O production during this process, and will use molecular techniques to investigate ammonifying populations in soil.