SS4.09 Does Intentional Nutrient Fertilization (N,P And Fe) Foster C Sequestration and/or Increased Fish Fertilization?
Date: Tuesday, June 11, 2002
Time: 12:00:00 PM
Location: Colwood
 
Mortimer, R, , Leeds University, Leeds, United Kingdom, r.mortimer@earth.leeds.ac.uk
Harris, S, , Leeds University, Leeds, United Kingdom, sansha@earth.leeds.ac.uk
KromM, Leeds University, Leeds, United Kingdom, m.d.krom@earth.leeds.ac.uk
Freitag, T, , University of Aberdeen, Aberdeen, United Kingdom, t.Freitag@abdn.ac.uk
Prosser, J, , University of Aberdeen, Aberdeen, United Kingdom, j.prosser@abdn.ac.uk
Davies, I, , FRS., Marine Laboratory, Aberdeen, United Kingdom, daviesim@marlab.ac.uk
Hayes, P, , FRS., Marine Laboratory, Aberdeen, United Kingdom, hayesp@marlab.ac.uk
 
EVIDENCE FOR SUB-OXIC NITRIFICATION IN ORGANIC-RICH MARINE SEDIMENTS BASED ON GEL PROBE AND 16S-rDNA & 16S-rRNA GENETIC ANALYSIS
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Profiles of dissolved nitrate in the pore waters of organic-rich marine sediments obtained using DET-gel probes show in addition to the usual subsurface nitrate maximum due to conventional nitrification-denitrification, much larger non-steady state nitrate peaks (0.6-1 mM) at the boundary between the iron and sulphate reduction zones. The initial observation of this peak was based on Ion Chromatograph measurements. The observation has now been repeated on a different core using a micro Cu/Cd reduction technique. DNA probe signals suggest an abundance of obligate ammonia oxidising bacteria throughout the depth interval sampled (40cm). RNA signals suggest that at least some of this population is active throughout the sub-oxic zones within the sediment. The large non-steady state pore water nitrate peak at the boundary between the iron and sulphate reduction zone is shown to correlate with DNA and RNA anomalies in the community of ammonia oxidising bacteria. These data taken together provide clear evidence for a nitrification-denitrification coupled much deeper into anaerobic sediments than was previous observed.