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Description of PhD

Title:  Volcanogenic sulfate and fluoride deposition- Effects on peatland gas fluxes and soil chemistry

Supervisor(s):  Dr. Pierre Delmelle and Vincent Gauci (Open University)

TAC:  Prof. Mike Ashmore, Prof. Malcolm Cresser and Dr. Sylvia Toet

Funding:  NERC

Description of Thesis

Recently, a link has been found between volcanic deposition of sulphate (SO₄) and the suppression of methane (CH₄) emissions from peatlands.  This link stems from the widely accepted idea that acid rain SO₄ additions to peatlands can cause a shift in microbial communities as SO₄ reducing bacteria out-compete methanogens for substrates, which, results in a suppression of CH₄ emission.  However, volcanic emissions contain other chemically reactive species that are potentially harmful to the environment. For example, a single volcano like Mt. Etna, Sicily, releases more hydrogen fluoride than all industrial activities in Europe. Thus, gaseous and particulate Fluoride (F) emissions from volcanoes certainly constitute a steady or intermittent source of F emission and deposition into the environment both close to the source and within fallout range of large eruptions. The objective of my research is to investigate the proposed link between volcanic depositions of SO₄, both alone and in combination with F, and CH₄ suppression in peatlands.  This investigation has been carried out using a long-term mesocosm experiment to look at the effects of volcanic SO₄ and F on peatlands not only looking at CH₄ emissions but also soil respiration, photosynthesis and soil solution chemistry.  This research will provide a greater understanding of the effects of volcanogenic F and SO₄ deposition on carbon (C) cycling in peatlands from temperate countries which will have important implications for evaluating the role of volcanic activity in influencing the terrestrial C cycle and hence climate.

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