We compared growth kinetics of Prorocentrum donghaiense cultures on different nitrogen (N) compounds including nitrate (NO3 ), ammonium (NH4 ), urea, glutamic acid (glu), dialanine (diala) and cyanate. P. donghaiense exhibited standard Monod-type growth kinetics over a range of N concentraions (0.5–500 mmol N L for NO3 2 and NH4 , 0.5–50 mmol N L for urea, 0.5–100 mmol N L for glu and cyanate, ...

[1] Longitudinal and diel measurements of dual isotope composition (dN and dO) in nitrate (NO3-N) were made in the Ichetucknee River, a large ( 8 m s ), entirely spring-fed river in North Florida, to determine whether isotopic variation can deconvolve assimilatory and dissimilatory removal. Comparing nitrate concentrations and isotope composition during the day and night we predicted (1) daytim...

Animal manures are a valuable resource, providing readily available plant nutrients ; however, runoff from lands receiving animal manure has been shown to contribute to water pollution. Understanding the loss of nutrients from slow release fertilizers, such as animal manure, after application is critical in determining and designing practices to reduce and/or control the temporal availability a...

Riparian ecosystems, through their unique position in the agricultural landscape and ability to influence nutrient cycles, can potentially reduce NO3 loading to surface and ground waters. The purpose of this study was to determine the fate of NO3 in shallow groundwater moving along a lateral flowpath from a grass seed cropping system through an undisturbed mixed-species herbaceous riparian area...

Maximization of short-rotation forest plantation yield requires frequent applications of nutrients, especially nitrogen (N). Whole-plant growth is known to be sensitive to the proportion of ammonium to nitrate (NH4:NO3). However, the extent to which N form affects root growth, branching and morphology is poorly understood, and these variables may have substantial impacts on plant nutrient and w...

1997). Ferguson et al. (2002) found reduction in soil nitrate concentration due to variable rate fertilizer N High levels of residual soil NO3–N can contaminate ground water application in only 3 out of 12 site-years as compared by leaching through the soil. Our objective was to reduce the level and spatial variability of residual soil NO3–N while maintaining optiwith uniform N application. Mac...

We measured the metabolites of NO [nitrite (NO2-) and nitrate (NO3-)] in urine from Ethiopian patients suffering from leprosy. The urinary level of NO2-/NO3- in a group of healthy Ethiopians was 1020 +/- 471 microM (n = 22). Leprosy patients in reversal reaction had significantly higher levels of NO2-/NO3- (1817 +/- 492 microM, p < 0.001, n = 12) than both the control group and leprosy patients...

Wet tropical forests growing on highly weathered soil, depleted in rockderived nutrients, yet rich in nitrogen (N), may respond quite differently to anthropogenic N inputs than those growing on younger soils low in N. We evaluated the effects of firsttime and long-term N additions on the pattern and regulation of hydrologic N losses from wet tropical forests located at the extreme ends of a soi...