The relationship between the accumulation of nitrate in the soil and its concentration in groundwater and in various plant systems is still not fully understood, but it indicates a high correlation between nitrate leaching and environmental and managerial factors. In this study in order to model the movement of nitrate in the soil profile and loss of fertilizer in the root zone using NLEAP GIS ...

Sugar beets (Beta vulgaris L. cv F58-554H1) were grown hydroponically in a 16-h light, 8-h dark period at a photosynthetic photon flux density of 0.5 mmol m-2 s-1 for 4 weeks in half-Hoagland culture solution containing only nitrate-nitrogen. Half of the plants were then transferred to half-Hoagland solution with ammonium-nitrogen (7.35mM), while the other half continued on 7.5 mM nitrate. Grow...

The hydrothermal vent tubeworm Riftia pachyptila lacks a mouth and gut and lives in association with intracellular, sulfide-oxidizing chemoautotrophic bacteria. Growth of this tubeworm requires an exogenous source of nitrogen for biosynthesis, and, as determined in previous studies, environmental ammonia and free amino acids appear to be unlikely sources of nitrogen. Nitrate, however, is presen...

Inorganic nitrogen is commonly found in three different forms: Ammonia (NH4), nitrite (NO2), and nitrate (NO3). Ammonia is a principle form of nitrogen found in urban wastewater and runoff especially from pastures and feedlots. According to Kadlec and Knight (1996), ammonia, or ammonium nitrogen, is the preferred nutrient form for most wetland plants because of its importance in plant growth. A...

Diatoms are a dominant group of eukaryotic phytoplankton that contribute substantially to global primary production and the cycling of important elements such as carbon and nitrogen. Heterotrophic bacteria, including members of the gammaproteobacteria, are commonly associated with diatom populations and may rely on them for organic carbon while potentially competing with them for other essentia...

A baseflow survey of 41 tributary creeks investigated the tiansport of alrazine, nilrate-nitrom chloride and sulfate in two 5,000 ha Jasper County, Iowa watersbeds. The waterskds comprise a long-tam paired shldy to evaluate the effects of largesale conversion of row nop to prairie in Walnut creek watershed compared to highly agricultural Squaw creek watershed. Discharge and chemical concentrati...