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...

In a wheat/maize rotation system, nitrogen (N) accounts for large proportion of basal fertilizer, but soil N loss and the resulting environmental risk simultaneously exist worldwide. This study applied different urease/nitrification inhibitors together with fertilizers investigated their effects on level grain yield. Six stabilizing combinations consisted two urease (HQ NBPT) three nitrificatio...

Nitrate was formed from ammonium at pH 3.2 to 6.1 in suspensions of a naturally acid forest soil; the maximum rates of formation occurred at ca. pH 4 to 5. Nitrate was also formed from soil nitrogen in suspensions incubated at 50 degrees C. Autotrophic nitrifying bacteria could not be isolated from this soil. Enrichment cultures produced nitrate in a medium with beta-alanine if much soil was ad...

Carbon disulfide has long been recognized as a potent inhibitor of nitrification, and it is the likely active component in several nitrification inhibitors suitable for field use. The effects of this compound on Nitrosomonas europaea have been investigated, and the site of action has been determined. Low concentrations of CS2 (less than 400 microM) produced a time-dependent inhibition of ammoni...

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...

Urethanes have marked physiological activity in plants and animals. Lefevre (1939) found that phenyl urethane affects wheat germination, and subsequently Templeman and Sexton (1946) showed that a variety of urethanes suppress the germination of wheat and oats without affecting charlock. The most active urethanes (for example, isopropylphenylcarbamate;ethylphenylcarbamate) are effective at a con...

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...