نتایج جستجو برای: no3
تعداد نتایج: 7056 فیلتر نتایج به سال:
Protecting water resources from nitrate-nitrogen (NO3-N) contamination is an important public health concern and a major national environmental issue in China. Loss of NO3-N in soils due to leaching is not only one of the most important problems in agriculture farming, but is also the main factor causing nitrogen pollution in aquatic environments. Three typical intensive agriculture farmlands i...
The opposite orientation of the ester spacers in the rodlike ligands L 4C12 (benzimidazole-OOC-phenyl) and L 5C12 (benzimidazole-COO-phenyl) drastically changes the electronic structure of the aromatic systems, without affecting their meridional tricoordination to trivalent lanthanides, Ln(III), and their thermotropic liquid crystalline (i.e., mesomorphic) behaviors. However, the rich mesomorph...
Polymer electrolyte membranes consisting of Cu(NO3)2 and poly(2-ethyl-2-oxazoline) (POZ) were prepared for SF6/N2 separation. It was anticipated that repulsive forces would be operative between the negative charge of water and the F atoms of SF6 when Cu(NO3)2 in the composite was solvated by water, and that the barrier effect of Cu(2+) ions would be activated. In fact, Cu(NO3)2 solvated by wate...
Five methods for estimating maximum daily and annual nitrate (NO3) and suspended sediment loads using periodic sampling of varying intensities were compared to actual loads calculated from intensive stormflow and baseflow sampling from small, forested watersheds in north central West Virginia to determine if the less intensive sampling methods were accurate and could be utilized in TMDL develop...
A series of platinum(II) complexes of the type [Pt(NN)(pyB)2](NO3)2 (NN = bipy, phen; pyB = 3- or 4-pyridineboronic acid) were successfully prepared and fully characterised by 1D- and 2D-multinuclear NMR spectroscopy and ESI-MS. Using VT 1H NMR spectroscopy, rotational isomers for [Pt(NN)(3-pyB)2](NO3)2 were identified and the free energies of activation for rotation of 3-pyB about the Pt-N bon...
it more susceptible to leaching (Albus and Knighton, 1998). Higher moisture contents will also raise microbial Groundwater and surface water are significant resources for rural activity including mineralization (Skopp et al., 1990). water supplies, and certain agricultural practices may have substantial effects on these resources. An 11-yr study was started in 1989 near The increase in minerali...
The concentration and amounts of NO3-N and TN transported in surface, accelerated subsurface, and subsurface runoff and stream flow draining a 20 ha pasture watershed were measured over a period of 3 yr. A slight decrease and increase of NO3-N and particulate N concentrations, respectively, were obtained with increased flow of the runoff types and stream, due to dilution and increased sediment ...
The Catskill Mountains of southeastern New York receive relatively high rates of atmospheric N deposition, and NO3 concentrations in some streams have increased dramatically since the late 1960s. We measured the chemistry of 39 firstand second-order streams with forested watersheds to determine the variability of nitrogen concentrations within the Catskill Mountain area. We found that some stre...
Leaching of NO3-N from agricultural lands often occurs in well-defined hot spot areas when viewed across geographical regions of hundreds or thousands of km 2 and often appears as areas of high NO3-N concentrations in shallow underlying aquifers. Delineation of high-NO3-N zones can be achieved by combining models such the Nitrate Leaching and Economic Analysis Package (NLEAP) with Geographical ...
The potential for microbially catalyzed NO3(-)-dependent oxidation of solid-phase Fe(II) compounds was examined using a previously described autotrophic, denitrifying, Fe(II)-oxidizing enrichment culture. The following solid-phase Fe(II)-bearing minerals were considered: microbially reduced synthetic goethite, two different end products of microbially hydrous ferric oxide (HFO) reduction (bioge...
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