Low nitrogen availability in the high Arctic represents a major constraint for plant growth, which limits the tundra capacity for carbon retention and determines tundra vegetation types. The limited terrestrial nitrogen (N) pool in the tundra is augmented significantly by nesting seabirds, such as the planktivorous Little Auk (Alle alle). Therefore, N delivered by these birds may significantly ...

The seasonal nutrient mass balance of the dominant seagrass of the Mediterranean, Posidonia oceanica (L.) Delde, was evaluated in NE Spain in order to test the hypothesis that the effect of seasonal nutrient imbalance can be reduced by the reutllization of internal nutrient pools. To this end we investigated the seasonal and age-dependent variability of nitrogen and phosphorus concentration of ...

Symbioses between sponges and algae are abundant in the nutrient-poor waters of tropical reefs, yet very little is known of the nutritional interactions that may promote this abundance. We measured nitrogen flux between the sponge Haliclona cymiformis and its symbiotic partner, the rhodophyte Ceratodictyon spongiosum, and assessed the potential importance of this flux to the symbiosis. While th...

Traditional models of chemostat systems looking at interactions between predator, prey and nutrients have used only a single currency, such as energy or nitrogen. In reality, growth of autotrophs and heterotrophs may be limited by various elements, e.g. carbon, nitrogen, phosphorous or iron. In this study we develop a dynamic energy budget model chemostat which has both carbon and nitrogen as c...

As for the East Asian countries, the total amount of government debt in Korea has risen sharply over the following several years in the wake of the Asian financial crisis. The purpose of this paper is to assess whether the current levels of government debt are sustainable for a severely attacked country, namely, Korea. Under the intertemporal budget constraint model, the study tests for fiscal ...

[1] The biogeochemistry of continental shelf systems plays an important role in the global elemental cycling of nitrogen and carbon, but remains poorly quantified. We have developed a high-resolution physical-biological model for the U.S. east coast continental shelf and adjacent deep ocean that is nested within a basin-wide North Atlantic circulation model in order to estimate nitrogen fluxes ...

In PNAS (1), we highlight changes in the balance of oxidized and reduced nitrogen contributions to US reactive nitrogen (N) deposition. Successful reductions in nitrogen oxides (NOx) emissions combined with modest growth in ammonia emissions have now tipped the balance in most regions toward deposition of reduced N species, ammonia and ammonium. Liu et al. (2) respond, making two main points. F...

Observations of the temporal and spatial distribution of N,.O in solution are not yet sufficient topermit quantitative assessment of the role of the ocean in the budget of atmospheric N,.O. Consideration of the global nitrogen cycle suggests hat the land should be the primary source of N20. The gas is removed in the atmosphere by photolysis and by reaction with O(•D), and there may be additiona...

Measurements of the N2 produced by denitrification, a better understanding of non-canonical pathways for N2 production such as the anammox reaction, better appreciation of the multiple environments in which denitrification can occur (e.g. brine pockets in ice, within particles outside of suboxic water, etc.) suggest that it is unlikely that the oceanic denitrification rate is less than 400 Tg N...

Abstract Based on rare and original in situ measurements together with published data, we estimate a complete nitrogen (N) budget for semi-arid Sahelian grazed grassland located Dahra (Senegal) 2014 2017. Nitrogen inputs include biological fixation, dry wet atmospheric deposition, input from livestock manure. outputs nitric oxide (NO) nitrous (N 2 O) emissions soils, NO ammonia (NH 3 ) biomass ...