Dissolved organic nitrogen (DON) produced by the nitrogen-fixer Trichodesmium sp. has the potential to serve as a nitrogen source for the red tide dinoflagellate Karenia brevis. Dissolved organic matter (DOM) from laboratory cultures of Trichodesmium sp. was isolated, concentrated and then supplied as a nutrient source to K. brevis cells collected from the Gulf of Mexico. K. brevis abundance in...

Nitrogen isotope values from coral tissue collected over depth-light gradients are reported from Jamaica and Zanzibar. The Jamaica suite consists of multiple specimens of three coral species (Montustrea annularis, Porites astreoides, and Agaricia agaricites) sampled at increasing depths. For each species, combined tissue/zooxanthellae 615N decreases significantly with decreasing availability of...

in this study the effect of nitrogen form and different oxygen levels on growth and development and macronutrients concentrations in lettuce plants was investigated. this investigation showed that sole ammonium application caused fresh and dry weight reduction of shoot and root in lettuce plant. but different oxygen levels had no effect on them. nitrogen concentration of shoot was higher in amm...

[1] We measured dN signatures of macrophytes and particulate organic matter (POM) in six estuaries and three freshwater ponds of Massachusetts to assess whether the signatures could be used as indicators of the magnitude of land-derived nitrogen loads, concentration of dissolved inorganic nitrogen in the water column, and percentage of N loads contributed by wastewater disposal. The study focus...

The leachate contains dissolved and suspended organic and inorganic, toxic or chemicals pollutants. Leachate can contaminate groundwater, surface water and soil. It can further have detrimental health effects on human being. This study sets out to investigate the effects of land treatment of municipal landfill’s leachate on the natural reduction of nitrogen and phosphorous density existing in t...

In the context of the global nitrogen cycle, the importance of inorganic nitrate for the nutrition and growth of marine and freshwater autotrophic phytoplankton has long been recognized. In contrast, the utilization of nitrate by heterotrophic bacteria has historically received less attention because the primary role of these organisms has classically been considered to be the decomposition and...

Next to N2 gas, the largest pool of reduced nitrogen in the ocean resides in the enormous reservoir of dissolved organic nitrogen (DON). The chemical identity of most of this material, and the mechanisms by which it is cycled, remain fundamental questions in contemporary oceanography. Amino acid enantiomeric ratios in the high molecular weight fraction of DON from surface and deep water in thre...

In an investigation of the mechanism responsible for the transport of water through Si02 thin films, we have performed tracer diffusion measurements involving network 0 demonstrating the importance of oxygen exchange between the Si02 network and molecularly dissolved water. We have found that in the presence of water, bound network oxygen diffuses through Si02 as a constituent of molecularly di...