Excess nitrogen (N) caused by straw returning to paddy fields undergoing flooding irrigation deteriorates the water quality. The purpose of this research was use both simulated field and pot experiments explore a new approach using zeolite recycle excess N. results from in stagnant showed N adsorption with different applications (25, 50, 75, 100, 125, 150 g L−1). Pot revealed how reused affecte...

Few studies have quantified the effects of different levels and forms of nitrogen (N) deposition on soil nitrous oxide (N2O) emissions from temperate forest soils. A 5-year field experiment was conducted to investigate the effects of multiple forms and levels of N additions on soil N2O emissions, by using the static closed chamber method at Xi Mountain Experimental Forest Station in northern Ch...

A novel reactor design, coined a high density bioreactor (HDBR), is presented for the cultivation and study of high density microbial communities. Past studies have evaluated the performance of the reactor for the removal of COD(1) and nitrogen species(2-4) by heterotrophic and chemoautotrophic bacteria, respectively. The HDBR design eliminates the requirement for external flocculation/sediment...

Incubation experiment was conducted on four soil types in Nigeria using cattle dung (CD) at the rate of 2.5g/kg soil ( 5 t ha), Urea fertilizer at the rate of 0.1g/kg soil ( 200 kg ha ) and cattle dung (2.5g/kg soil) combined with Urea 0.05g/kg soil (100 kg ha) as treatments. The objective of the experiment was to compare the rate of OC, NH4 – N, NO3 – N and available P release on soils selecte...

The obligately ammonia-oxidizing bacterium Nitrosomonas europaea was incubated in medium containing 50 mM ammonium. Changes in the concentration of nitrite, the pH, and the NH4 and NH2OH-dependent O2 uptake activities of the cell suspension were monitored. The NH4 -dependent O2 uptake activity doubled over the first 3 h of incubation and then slowly returned to its original level over the follo...

OsNRT1.1a is a low-affinity nitrate (NO3 (-) ) transporter gene. In this study, another mRNA splicing product, OsNRT1.1b, putatively encoding a protein with six transmembrane domains, was identified based on the rice genomic database and bioinformatics analysis. OsNRT1.1a/OsNRT1.1b expression in Xenopus oocytes showed OsNRT1.1a-expressing oocytes accumulated (15) N levels to about half as compa...

A freshwater "mussel mortality threshold" was explored as a function of porewater ammonium (NH4+) concentration, mussel biomass, and total nitrogen (N) utilizing a numerical model calibrated with data from mesocosms with and without mussels. A mortality threshold of 2 mg-N L-1 porewater NH4+ was selected based on a study that estimated 100% mortality of juvenile Lampsilis mussels exposed to 1.9...

Both nitrate (NO3-N) and ammonia (NH4-N) concentrations are in general highly variable during a lake’s seasonal cycle. During the growing seasonal peak, such concentrations can be very low due mainly to its’ sequestration by phytoplankton. With the aim to study NO3-N and NH4-N mean concentration variation along the increase of the trophic state of lakes, this study simultaneously analyses the i...

Relatively little is known about the fixed NH4-N status of soils in the semi-arid tropics (SAT) but information is needed in view of its role in N cycling and the N economy of the soils. The distribution of fixed NI-L-N and C/N ratios of soil profiles from two benchmark Vertisols and one Alfisol in the Indian SAT were studied. From 15.9 to 58.6% of the total soil N was present as fixed NHa-N in...