Project description
Methane-related iron reduction impact on biogeochemical cycles
About one third of annual naturally produced methane emissions reach the atmosphere. Iron oxide limits methane emissions when sulfate concentrations are low. However, methane-iron couplings in established sediments are not entirely understood. Significant iron oxide reduction has been observed in many aquatic sediments at depths well below its expected redox zone. The EU funded MERIR project will study the unexplored mechanisms of methane related iron reduction in the methanogenic zone and their impact on global biogeochemical cycles. The project will elucidate the active involvement of aerobic methanotrophs in iron-coupled anaerobic oxidation of methane and analyse the unusual reactivity of iron minerals towards reduction and its effects on sedimentary magnetism.
Objective
About one-third of annual methane (CH4) emissions to the atmosphere originate from natural, nonanthropogenic
sources. However, if all the naturally produced methane actually did reach the atmosphere, its
levels would increase by an order of magnitude, dwarfing anthropogenic CO2 emissions. Fortunately, natural
scavengers of this methane near its production zone limit its release. One of these scavengers, iron (Fe) oxide,
can become a major sink for methane when sulfate concentrations are low. Methane-iron couplings in
established sediments, however, are poorly understood. Specifically, significant iron oxide reduction has been
observed in many aquatic sediments at depths well below its expected redox zone, where methane is produced
by methanogenesis, often accompanied by decreases in methane concentrations. These observations challenge
our understandings of iron-methane couplings and microbial players in the deep methanogenic zone and their
impacts on the carbon, iron and other cycles. I aim in the proposed research to elucidate the unexplored
mechanisms of methane-related iron reduction (MERIR) in the methanogenic zone of established
sedimentary profiles under various environmental conditions and their impact on global biogeochemical
cycles. I will resolve two striking yet unexplained phenomena: (1) the active involvement of aerobic
methanotrophs in iron-coupled anaerobic oxidation of methane (AOM), and (2) the unusual reactivity
of iron minerals toward reduction that is accompanied by intensive authigenic magnetite precipitation, and
the effects of this mineralogy change on sedimentary magnetism. My expertise will enable me to achieve the
objectives of this interdisciplinary proposed work using novel approaches from different fields. The project
will likely lead to breakthroughs in our understanding of microbial survival strategies, reveal novel pathways
for aerobic methanotrophs, and change our perspectives on iron mineral reactivities and sedimentary
magnetism.
Fields of science
Keywords
Programme(s)
Funding Scheme
ERC-COG - Consolidator GrantHost institution
84105 Beer Sheva
Israel