Simultaneous measurements of nitrification in the Baltic Sea were made at 10- to 30-m intervals in the months of June and November by three isotope techniques: [N]nitrate dilution, N-serve sensitive [C]bicarbonate incorporation, and [N]ammonium oxidation to nitrite and nitrate. Nitrification rates of 1 to 280 nmol liter day were recorded, and each method showed that the highest rates of nitrifi...

Modern agriculture has promoted the development of high-nitrification systems that are susceptible to major losses of nitrogen through leaching of nitrate and gaseous emissions of nitrogen oxide (NO and N2O), contributing to global warming and depletion of the ozone layer. Leakage of nitrogen from agricultural systems forces increased use of nitrogen fertilizers and causes water pollution and e...

November or before April because soils either are frozen or too wet. Soil temperature at the time of application has been the primary It has been recommended that fall applications of N factor used to predict rates of nitrification and assess the risks associbe delayed until soil temperature has decreased to 10 C ated with losses of N applied in the fall as anhydrous ammonia in the at a depth o...

Two biofilm reactors operated with hydraulic retention times of 0.8 and 5.0 h were used to study the links between population dynamics and reactor operation performance during a shift in process operation from pure nitrification to combined nitrification and organic carbon removal. The ammonium and the organic carbon loads were identical for both reactors. The composition and dynamics of the mi...

Ammonia oxidation is an important process for decreasing ammonia concentrations in wastewater-impacted rivers. Ammonia-oxidizing bacteria (AOB) and archaea (AOA) are re sponsible for ammonia oxidation, which is the first step of the nitrification process. Nitrification and urea hydrolysis were monitored in sediment and water column samples in the Grand River (Ontario), and nitrification inhibit...

Oysters provide a critical habitat, are a food resource for higher trophic levels and support important commercial fisheries throughout the world. Oyster reefs can improve water quality by removing phytoplankton. While sediment denitrification may be enhanced adjacent to oyster reefs, little is known about nitrification and denitrification associated with living oysters and their shells. We mea...

Biochemical processes by chemoautotrophs such as nitrifiers and sulfide and iron oxidizers are used extensively in wastewater treatment. The research described in this dissertation involved the study of two selected biological processes utilized in wastewater treatment mediated by chemoautotrophic bacteria: nitrification (biological removal of ammonia and nitrogen) and hydrogen sulfide (H2S) re...

Composting is the major technology in the treatment of animal manure and is a source of nitrous oxide, a greenhouse gas. Although the microbiological processes of both nitrification and denitrification are involved in composting, the key players in these pathways have not been well identified. Recent molecular microbiological methodologies have revealed the presence of dominant Bacillus species...

A modified oxygen uptake rate (OUR) test for characterizing the performance of integrated fixed-film activated sludge (IFAS) processes was developed while monitoring the startup of a full-scale demonstration facility. Data on total biofilm solids, in-basin nitrification rates, and batch nitrification rates were compared to the OUR test. The data was used to investigate dynamic changes in the ph...

Maintaining effective solids capture and nitrification can determine the success or failure of a recirculating aquaculture system (RAS). Although solids capture and nitrification are often performed sequentially, they are united in floating-bead filters. The use of bead filters in a RAS began at the Dworshak National Fish Hatchery (Cooley 1979). More recently, a bead filter was developed and te...