abstractabout 30 to 50 percent of applied nitrogen fertilizers leached from soil to ground waters which can causes environment contamination and various human health problems. the rotation type can affect nitrogen mobility rate, so it is necessary to study effect of rotation type in on nitrogen movement. in order to evaluate effects of three main rotations in khuzestan province on inorganic for...

We examine the formation of nitrate and ammonium on five types of externally mixed pre-existing aerosols using the hybrid dynamic method in a global chemistry transport model. The model developed here predicts a similar spatial pattern of total aerosol nitrate and ammonium to that of several pioneering studies, but separates the effects of nitrate and ammonium on pure sulfate, biomass burning, ...

the microalgae, dunaliella salina was isolated from maharlu salt lake, south east of shiraz, iran. the isolated strain was identified by both morphological and physiological markers. the complete its region (its1 + its2) including the 5.8s rdna gene used as molecular marker confirmed our identification. growth and cell proliferation, total chlorophyll and carotenoid contents were determined in ...

A basic tenet of nitrogen utilization in phytoplankton is that ammoniuln inhibits nitrate uptake. Consequently, it is generally believed that little or no nitrate uptake occurs at ammonium concentrations above ca 1 yM. A thorough review of field studies shows that the reduction of nitrate uptake rate in the presence of ammonium is rarely so severe, and that it is a highly variable phenomenon. T...

Lambir Hills National Park in Malaysian Borneo is composed of dipterocarp tree species which specialize on different soil types. Although the mechanisms contributing to this distribution of tree species are unknown, one hypothesis is that tree species at Lambir differ in their preferences for different nitrogen forms. In this study we investigated (1) whether clay soil and sandy loam soil types...

Synthesis of wild-type Neurospora crassa assimilatory nitrate reductase is induced in the presence of nitrate ions and repressed in the presence of ammonium ions. Effects of several Neurospora mutations on the regulation of this enzyme are shown: (i) the mutants, nit-1 and nit-3, involving separate lesions, lack reduced nicotinamide adenine dinucleotide (NADPH)-nitrate reductase activity and at...

In the manufacturing of ammonium nitrate, a condensate containing ammonia and ammonium nitrate is obtained. The concentrations of these species are in practically all cases too high for direct discharge into a water recipient. At some plants, some of the dilute ammonium nitrate solution can be spread out on adjacent farmland, as it is a fertilizer, but commonly, nitric acid is added to this str...