Aquatic Sciences Meeting, Albuquerque 2001
| CS07 Biogeochemical Cycles |
| Date: Thursday, February 15, 2001, Time: 10:30:00 AM |
| Location: Cochiti/Taos |
| Dalsgaard, T, , National Environmental Research Institute, Silkeborg, Denmark, tda@dmu.dk |
| Thamdrup, B, , Institute of Biology, Odense University, Odense, Denmark, bot@biology.sdu.dk |
| ANAEROBIC AMMONIUM OXIDATION IN MARINE SEDIMENTS |
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| The fate of ammonium was investigated in Skagerrak sediment from 700 m depth halfway between Norway and Denmark. Ammonium was oxidised in the anoxic sediment, the oxidant was nitrate and the end product of the process was dinitrogen. When 15N-nitrate and 14N-ammonia was added to the sediment 29N-dinitrogen was formed. This was also the case if 15N-ammonium and 14N-nitrate was added but when 15N-nitrate and 15N-ammonium was added 30N-dinitrogen was formed. This indicates that dinitrogen was formed with one N atom from nitrate and one from ammonium. This process resembles the "Anamox" process known from a waste water treatment plant in Holland but this is to our knowledge the first time anaerobic ammonium oxidation with nitrate has been documented in natural environments. In previous studies oxidation of ammonium to nitrate or directly to dinitrogen with manganese oxides was suggested. Since the Skagerrak sediment is very rich in manganese oxides these possibilities were investigated but no evidence for any such oxidation pathway was found. Current studies of the anaerobic ammonium oxidation and its occurrence in other marine sediments will be discussed. |
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