Ben Fisher

Ben Fisher

Profile

I am a Masters by Research student in Earth Sciences, focusing on Biogeochemistry. Broadly, I am interested in how biological processes can have global environmental impacts and inversely, how the changing planet may affect living organisms. I am a Biologist by training with most of my biological interest focusing on the microbial processes associated with organic carbon in nutrient limited environments. I now use a wide range of biological, chemical and geological technqiues to better understand the geochemical conditions that result from microbial degredation, forming the basis of my research project. 

Research interests

Implications of Carbon:Iron interactions for organic matter preservation and global climate systems. 

All living matter in the Ocean is eventually degraded upon death and becomes buried in sea floor sediment. A large portion of this is dissolved organic matter (DOM), comprised of carbon, which is accessible by heterogenous bacteria in the upper oxic layers and can be aerobically respired. Despite this microbial activity, organic matter continues to be preserved and appears inacsessible to bacteria. Different mechanisms for organic matter preservation have been proposed, with one of the main focuses being on mineral based protection, whereby metal oxides sorbed to organic matter protect the carbon from degredation. Iron (hydr)oxides are one of the most common minerals studied due to their environmental ubqiuity and defined presence in sediment, they typically enter the ocean through aerosols or as an impurtiy from ice sheet melt. Organic matter preservation has wide implications for global carbon budgets, with the ocean being the major carbon sink for anthropogenically released carbon dioxide. I work with samples retrieved from the Barents Sea in the Arctic Ocean which represents one of the most radically changing environments on earth as a result of climate change, this poses interesting questions for carbon:iron interactions due to an increase in surface area for photosynthetic plankton to produce organic carbon and increased iron liberation from ice sheet melt. Large scale geoengineering projects, namely ‘Iron fertilisation’ have aimed to exploit precieved organic matter preservation mechanisms to increase atmopsheric carbon dioxide draw down, with limited succsess. While the extent of carbon preservation is now well understood, the mechanisms are less so. In part this is due to a diffuclty in quantification and specicifity of chemical extraction techniques. My project aims to further understanding of this mechanism by adressing three key questions:

  • How can an extraction technique be refined to quantitivley extract reactive iron hydr(oxides) (i.e do current methods extract all of the present iron).
  • Does organic matter preservation via carbon:iron interactions persist with sediment depth. 
  • Do high concentrations of iron in pore water have any relation with historical climate/atmopsheric carbon dioxide. (i.e can iron burial be a proxy for carbon burial). 

My project is conducted as part of the larger MINORG and ChAOS (NERC) research. 

Twitter: @BenFisher_

Qualifications

  • BSc Biological Sciences - University of Exeter (2019)

Research groups and institutes

  • Earth Surface Science Institute
  • Cohen Geochemistry