Strong atmospheric photochemistry in summer can produce a significant amount of secondary aerosols, which may have a large impact on regional air quality and visibility. In the study reported herein, we analyzed sulfate, nitrate, and ammonium in PM2.5 samples collected using a 24-h filter system at suburban and rural sites near four major cities in China (Beijing, Shanghai, Guangzhou, and Lanzh...

Chemically speciated concentrations of PM2.5 (sulphate, ammonium, nitrate, elemental and organic carbon) were simulated in south-west Europe using the three-dimensional air quality model CAMx driven by the MM5meteorological model. The inner domain covered the south-west region of Spain with a high spatial (2 km 2 km) and temporal resolution (1 h). The simulation results were evaluated against e...

BACKGROUND Lack of accounting for proton uptake and secretion has confounded interpretation of the stoichiometry of photosynthetic growth of algae. This is also problematic for achieving growth of microalgae to high cell concentrations which is necessary to improve productivity and the economic feasibility of commercial-scale chemical production systems. Since microalgae are capable of consumin...

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 study of inorganic nutrients dynamics in shallow sediments usually focuses on two main pools: porewater (PW) nutrients and exchangeable (EX) ammonium and phosphate. Recently, it has been found that microphytobenthos (MPB) and other microorganisms can accumulate large amounts of nutrients intracellularly (IC), highlighting the biogeochemical importance of this nutrient pool. Storing nutrient...

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...

Nitrogen is an essential soil nutrient for plants, and lack of nitrogen commonly limits plant growth. Soil nitrogen is typically available to plants in two inorganic forms: nitrate and ammonium. To better understand how nitrate and ammonium differentially affect plant metabolism and development, we performed transcriptional profiling of the shoots of ammonium-supplied and nitrate-supplied Arabi...

Marshall, K. C. (Cornell University, Ithaca, N. Y.) and M. Alexander. Nitrification by Aspergillus flavus. J. Bacteriol. 83:572-578. 1962.-Aspergillus flavus has been shown to produce bound hydroxylamine, nitrite, and nitrate when grown in peptone, amino acid, or buffered ammonium media. Free hydroxylamine was not detected in these cultures, but it was found in an unbuffered ammonium medium in ...

l-Glutamate uptake, thiourea uptake, and methylammonium uptake and the intracellular ammonium concentration were measured in wild-type and mutant cells of Aspergillus nidulans held in various concentrations of ammonium and urea. The levels of l-glutamate uptake, thiourea uptake, nitrate reductase, and hypoxanthine dehydrogenase activity are determined by the extracellular ammonium concentration...

Nitrate, ammonium, total dissolved nitrogen (TDN), dissolved organic nitrogen (DON) and dissolved organic carbon (DOC) concentrations and flux were measured for one year in bulk deposition and throughfall from three stand types (upland deciduous, upland conifer and wetland conifer) on the Boreal Plain, Canada. Annual (November 2006 to October 2007water year) flux rates in bulk depositionwere 80...