Several aspects of the topography of the membrane-bound respiratory nitrate reductase (EC 1.7.99.4) of Escherichia coli have so far been explored (Kemp et al., 1975; Boxer & Clegg, 1975; Jones &Garland, 1977,1978; MacGregor &Christopher, 1978). Nevertheless, the location of the nitrate-binding site has not yet been positively identified. Garland et al. ( 1 9 7 5 ~ ) noted that the rate of passi...

One of the ultimate goals of ion chromatography is to determine both anions and cations found in samples with a single chromatographic run. In the present article, recent progress in ion-exclusion/ion-exchange chromatography for the simultaneous determinations of inorganic anions and cations are reviewed. Firstly, the principle and the control for the simultaneous separation and detection of ...

1 Nitrification is an important microbial process in humid tropical ecosystems because of its effects on potentials for nitrogen loss via nitrate leaching and denitrification and on the hydrogen ion cycle. Nitrification rates in humid tropical soils vary markedly among different forest types but in general appear to increase following disturbance. Proximal controls on nitrifiers include ammoniu...

Surfactant-Modified MFI-Zeolite Nanosheets (SMZN) were used for the first time as anion-exchangers, in the case of nitrate ion removal. The SMZN material is characterized by high anionic exchange capacity and removal efficiency compared to classical SMZ prepared from clinoptilolite. The SMZN material is easily regenerated and could be probably employed to remove other anionic pollutants.

Abbreviations: CYA: czapek yeast extract agar DEPT: distortionless enhancement by polarization transfer DMF: dimethylformamide EIMS: electron-ionization mass spectrometry EtOAc: ethylacetate G25N: 25% glycerol nitrate agar HMBC: heteronuclear multiple bond correlation HMQC: heteronuclear multiple quantum coherence MEA: malt extract agar MIC: minimum inhibitory concentration NMR: nuclear magneti...

The aerodynamic gradient method is widely used for flux measurements of ammonia, nitric acid, particulate ammonium nitrate (the NH3-HNO3-NH4NO3 triad) and other water-soluble reactive trace compounds. The surface exchange flux is derived from a measured concentration difference and micrometeorological quantities (turbulent exchange coefficient). The significance of the measured concentration di...

background: surface water and groundwater pollution with various forms of nitrogen such as ammonium and nitrate ions is one of the main environmental risks. the major objectives of this study were to evaluate the capacity of natural zeolite (clinoptilolite) to remove no3- and nh4+ from polluted water under both batch and column conditions. methods: the laboratory batch and column experiments we...

Measurements of surface total carbon dioxide (TCO2) , alkalinity, and calculated pCO2, along with water column nutrients and hydrography, were made on two cruises to the Ross Sea polynya (NBP 94-6, November-December 1994 and NBP 95-8, December 1995 to January 1996). The polynya experiences an intense phytoplankton bloom during a short period of open water conditions from mid-December to midFebr...