Plant nitrogen (N) use is a key component of the N cycle in terrestrial ecosystems. The supply of N to plants affects community species composition and ecosystem processes such as photosynthesis and carbon (C) accumulation. However, the availabilities and relative importance of different N forms to plants are not well understood. While nitrate (NO3-) is a major N form used by plants worldwide, ...

We conducted NO3 – stable isotope tracer releases in nine streams with varied intensities and types of human impacts in the upstream watershed to measure nitrate (NO3 ) cycling dynamics. Mean ambient NO3 – concentrations of the streams ranged from 0.9 to 21,000 lg l NO3 – N. Major N-transforming processes, including uptake, nitrification, and denitrification, all increased approximately two to ...

Nitrate N fluxes from tile-drained watersheds have been implicated in water quality studies of the Mississippi River basin, but actual NO3-N loads from small watersheds during long periods are poorly documented. We evaluated discharge and NO3-N fluxes passing the outlet of an Iowa watershed (5134 ha) and two of its tile-drained subbasins (493 and 863 ha) from mid-1992 through 2000. The cumulati...

Controls of stream water NO3 in mountainous and forested catchments are not thoroughly understood. Longterm trends in stream water NO3 are positive, neutral and negative, often apparently independent of trends in N deposition. Here, time series of NO3 in four small acid-sensitive catchments in southern Norway were analysed in order to identify likely drivers of long-term changes in NO3. In two ...

The coordination behaviour of hexakis(3-pyridyloxy)cyclophosphazene (L) towards divalent metal ions is described. The reaction of L with hydrated metal nitrates afforded [{N3P3(O-C5H4N-3)6}2{Zn(H2O)3(NO3)}2{Zn(H2O)2(NO3)}2]n[NO3]2n·4nH2O·nCH3OH (1), [{N3P3(O-C5H4N-3)6}2{Zn(H2O)3(NO3)}2{Cu(NO3)}2]n[NO3]2n·4nH2O·nCH3CN (2), [{N3P3(O-C5H4N-3)6}2{(NO3)Cd-(μ-(NO3)-Cd(NO3)2(μ-(NO3)Cd(NO3)}]n·2nCH3OH·...

In the Southern Ocean, the nitrogen (N) isotopes of organic matter and the N and oxygen (O) isotopes of nitrate (NO3 ) have been used to investigate NO3 assimilation and N cycling in the summertime period of phytoplankton growth, both today and in the past. However, recent studies indicate the significance of processes in other seasons for producing the annual cycle of N isotope changes. This s...

Nitrate (NO3 ) can contribute to surface water eutrophication and is deemed harmful to human health if present at high concentrations in the drinking water. In grazed grassland, most of the NO3 -N leaching occurs from animal urine-N returns. The objective of this study was to determine the effectiveness of a nitrification inhibitor, dicyandiamide (DCD), in decreasing NO3 ) leaching in three dif...

We determined relative nitrate–nitrogen (NO3-N) loss rates in 100 north–mid-European lakes from late spring to summer by using the exponential function N2 5 N1e2 2 t2), where N1 and N2 are NO3-N concentrations at the beginning (t1) and the end (t2) of the time interval, respectively, and k is the specific NO3-N loss rate. We found that k decreased with increasing lake depth. Adjusting k to the ...

Nitrogen availability directly affects the microalgal metabolism. A thermophilic cyanobacterium named Thermosynechococcus CL-1 was cultivated in a continuous system to evaluate the effects of NO3 fluxes on the biomass production, bioenergy production, and CO2 fixation. The results show that decreasing the NO3 flux to a N-deprived level (1.01 mM/d) enhances the carbohydrate content in TCL-1 to 4...