The contribution of ammonification to N2O emissions from soils

该项目将研究一种被称为氨化作用的细菌过程在土壤中氧化亚氮（N2O）排放中的重要性。一氧化二氮可能是最常见的麻醉剂“笑气”。然而，从全球范围来看，一氧化二氮的排放可不是闹着玩的，因为它是一种强效的温室气体，可以在大气中存留数百年。这种气体的全球排放量每年都在上升，其中大部分来自生物来源。由于这种气体与全球变暖和平流层臭氧的破坏有关，这一点引起了极大的关注。因此，了解N2O释放背后的酶促过程、这些过程的调节以及细菌氨化过程中负责氧化亚氮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，后者也会导致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排放的全部情况。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产量，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.