Ammonium concentrations in produced waters from a mesothermic oil field subjected to nitrate injection decrease through formation of denitrifying biomass and anammox activity.
Community analysis of a mesothermic oil field, subjected to continuous field-wide injection of nitrate to remove sulfide, with denaturing gradient gel electrophoresis (DGGE) of PCR-amplified 16S rRNA genes indicated the presence of heterotrophic and sulfide-oxidizing, nitrate-reducing bacteria (hNRB and soNRB). These reduce nitrate by dissimilatory nitrate reduction to ammonium (e.g., Sulfurospirillum and Denitrovibrio) or by denitrification (e.g., Sulfurimonas, Arcobacter, and Thauera). Monitoring of ammonium concentrations in producing wells (PWs) indicated that denitrification was the main pathway for nitrate reduction in the field: breakthrough of nitrate and nitrite in two PWs was not associated with an increase in the ammonium concentration, and no increase in the ammonium concentration was seen in any of 11 producing wells during periods of increased nitrate injection. Instead, ammonium concentrations in produced waters decreased on average from 0.3 to 0.2 mM during 2 years of nitrate injection. Physiological studies with produced water-derived hNRB microcosms indicated increased biomass formation associated with denitrification as a possible cause for decreasing ammonium concentrations. Use of anammox-specific primers and cloning of the resulting PCR product gave clones affiliated with the known anammox genera "Candidatus Brocadia" and "Candidatus Kuenenia," indicating that the anammox reaction may also contribute to declining ammonium concentrations. Overall, the results indicate the following: (i) that nitrate injected into an oil field to oxidize sulfide is primarily reduced by denitrifying bacteria, of which many genera have been identified by DGGE, and (ii) that perhaps counterintuitively, nitrate injection leads to decreasing ammonium concentrations in produced waters.
Shartau
Sabrina L Cornish
SL
Petroleum Microbiology Research Group, Department of Biological Sciences, University of Calgary, 2500 University Dr. NW, Calgary, Alberta T2N 1N4, Canada.
Yurkiw
Marcy
M
Lin
Shiping
S
Grigoryan
Aleksandr A
AA
Lambo
Adewale
A
Park
Hyung-Soo
HS
Lomans
Bart P
BP
van der Biezen
Erwin
E
Jetten
Mike S M
MS
Voordouw
Gerrit
G
D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D044822:Biodiversity; D018533:Biomass; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D054892:Metagenome; D008969:Molecular Sequence Data; D009566:Nitrates / Q000378:metabolism*; D009691:Nucleic Acid Denaturation; D010084:Oxidation-Reduction; D010802:Phylogeny; D000644:Quaternary Ammonium Compounds / Q000032:analysis*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012988:Soil Microbiology; D013440:Sulfides / Q000378:metabolism; D014867:Water / Q000737:chemistry*
D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D009566:Nitrates; D000644:Quaternary Ammonium Compounds; D012336:RNA, Ribosomal, 16S; D013440:Sulfides; D014867:Water