Anchen Kehler

Name: Anchen Kehler

Project title: Soil Phosphine: The Missing Link in the Global Phosphorus Cycle 

Where based: Rothamsted Research and Lancaster University


At undergraduate level, I studied BSc (Hons) Chemistry at Plymouth University where I found the environmental aspects of the degree particularly interesting.  This led me to continue my studies with an MSc in Marine Sciences; made possible by receiving a scholarship from the University of Plymouth. Both my BSc and MSc research projects had a high focus on biogeochemical cycles and impacts surrounding environmentally significant elements and compounds, as well as involving many aspects of analytical method development.  These themes are what drove my interest towards my current Ph.D. as they run strongly throughout my project.

Project description:

Soils are a crucial sink and source in numerous biogeochemical cycles including the nitrogen cycle – an element that’s integral to complex life and crop growth. Nitrous oxide (N2O) is of particular interest because it is a powerful greenhouse gas (approximately 300 times more potent than carbon dioxide) and it depletes ozone in the stratosphere. Microbial activity is predominantly responsible for its release and the factors that impact these communities such as land use and soil moisture have been studied within short time frames. However, my project explores how historical soil moisture (weeks-months) and management (years-decades) might influence the microbial response to fertiliser application and the resulting N­2O emissions. The ultimate goal is to understand how these emissions can be reduced through changing agricultural practices.

Additional personal information: 

The occurrence of Phosphine in the natural environment and its role in the biogeochemical cycling of Phosphorus has been in dispute for many years, due to a poor characterization of its biogenic methods of production.  It is generally understood that microbial activity is a key factor for the release of natural Phosphine gas into our atmosphere at the soil-air interface.  However, there is no definitive pathway that has been identified for this process. We also remain unaware of just how environmentally significant Phosphine is or how likely it is going to become in the coming years as it has already been indirectly linked to increasing the greenhouse effect, as well as having regular interactions with prominent greenhouse gases such as CO2 andCH4. My project will have, as its primary objective, the testing of the hypothesis that methods of biological Phosphine production are dominant over chemical mechanisms; with the secondary objective of identifying the optimal conditions for the natural release of Phosphine.  To achieve this, I will aim to devise and optimise a methodology for the capture and analysis of natural Phosphine gas so that Phosphine levels in wetland locations around the UK can be quantified. Ultimately, I intended to revise the conceptual model for the soil Phosphorus cycle with a quantitative estimation of the role of Phosphine formation in soils and the underlying controlling mechanisms.

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