Effect of Nitrogen on the Degradation of Cypermethrin and Its Metabolite 3-Phenoxybenzoic Acid in Soil

Increasing use of pyrethroid insecticides has resulted in concerns regarding potential effects on human health and ecosystems. Cypermethrin and its metabolite 3-phenoxybenzoic acid(PBA) have exerted adverse biological impacts on the environment;therefore,it is critically important to develop different methods to enhance their degradation. In this study,incubation experiments were conducted using samples of an Aquic Inceptisol supplied with nitrogen(N) in the form of NH4NO3 at different levels to investigate the effect of nitrogen on the degradation of cypermethrin and PBA in soil. The results indicated that appropriate N application can promote the degradation of cypermethrin and PBA in soil. The maximum degradation rates were 80.0% for cypermethrin after 14 days of incubation in the treatment with N at a rate of 122.1 kg ha-1 and 41.0% for PBA after 60 days of incubation in the treatment with N at a rate of 182.7 kg ha-1. The corresponding rates in the treatments without nitrogen were 62.7% for cypermethrin and 27.8% for PBA. However,oversupplying N significantly reduced degradation of these compounds. Enhancement of degradation could be explained by the stimulation of microbial activity after the addition of N. In particular,dehydrogenase activities in the soil generally increased with the addition of N,except in the soil where N was applied at the highest level. The lower degradation rate measured in the treatment with an oversupply of N may be attributed to the microbial metabolism shifts induced by high N.

Effect of nitrogen on deposition and field emission properties of boron-doped micro-and nano-crystalline diamond films

In this paper,we report the effect of nitrogen on the deposition and properties of boron doped diamond films synthesized by hot filament chemical vapor deposition.The diamond films consisting of micro-grains(nano-grains) were realized with low(high) boron source flow rate during the growth processes.The transition of micro-grains to nano-grains is speculated to be strongly(weekly) related with the boron(nitrogen) flow rate.The grain size and Raman spectral feature vary insignificantly as a function of the nitrogen introduction at a certain boron flow rate.The variation of electron field emission characteristics dependent on nitrogen is different between microcrystalline and nanocrystalline boron doped diamond samples,which are related to the combined phase composition,boron doping level and texture structure.There is an optimum nitrogen proportion to improve the field emission properties of the boron-doped films.

Effect of Treatment Temperature on Iron Nitride Foils Irradiated with Nitrogen Plasma

We investigated the effect of treatment temperature on the magnetic property of iron nitride foils irradiated with nitrogen plasma. The iron nitride foils irradiated with nitrogen plasma were composed of ε-Fe2/3N, γ'-Fe4N and γ nitrogen austenite in α-Fe of the matrix. The saturation magnetization of the iron nitride foils decreased with increasing the surface temperature. The coercive force of the iron nitride foils increased with increasing the surface temperature.

Effect of nitrogen fertilizer on the uptake and utilization of potassium by various rice varieties in purple soil

Nitrogen and potassium are important nutrientelements for rice.Besides supplied by the or- ganic manure,potassium nutrition of ricecomes dominantly from purple soils in Sichuanbasin.Potassium exists abundantly in mineralforms in the purple soils.Availability of soilpotassium for crop depends on the potassiumforms,the uptake ability of crops,and fertiliz-er practices.A pot culture experiment wasconducted to study the kinetics of potassiumuptake in the purple soil(total N 22.64g·kg,total K 24.36g·kg,available N 102.6mg·kg,available K 140.6mg·kg,acidsoluble K 936.0mg·kg,and pH 6.8).Ma-terials used were three Fhybrid rices,Eryou

Nitrogen Plasma Treatment Effect on Graphene Sheeted Vertically Aligned Carbon Nanofibers

Nitrogen plasma treatment effect on GS-CNFs （graphene seeted vertically aligned carbon nanofibers） has been studied. GS-CNFs were grown on nickel coated cupper substrates by DC-plasma CVD （chemical vapor deposition） at relatively low temperature. GS-CNFs were studied by SEM （scanning electron microscopy）, HR-TEM （high-resolution transmission electron microscopy）, XPS and Raman measurements. GS-CNFs are composed of cylindrical shaped having pure graphite sheets with about 5 μm length and nanometer size tips and roots diameter. Nitrogen plasma treatment causes nitrogen chemical etching on the graphene seeted carbon nanofibers were disordered its fine shape and increase the graphetization due to nitrogen incorporation.

Fate of ^(15)N-Labeled Urea Under a Winter Wheat-Summer Maize Rotation on the North China Plain

A field experiment was conducted to investigate the fate of ^15N-labeled urea and its residual effect under the winter wheat （Triticum aestivum L.） and summer maize （Zea mays L.） rotation system on the North China Plain. Compared to a conventional application rate of 360 kg N ha^-1 （N360）, a reduced rate of 120 kg N ha^-1 （N120） led to a significant increase （P 〈 0.05） in wheat yield and no significant differences were found for maize. However, in the 0-100 cm soil profile at harvest, compared with N360, N120 led to significant decreases （P 〈 0.05） of percent residual N and percent unaccounted-for N, which possibly reflected losses from the managed system. Of the residual fertilizer N in the soil profile, 25.6%-44.7% and 20.7%-38.2% for N120 and N360, respectively, were in the organic N pool, whereas 0.3%-3.0% and 11.2%-24.4%, correspondingly, were in the nitrate pool, indicating a higher potential for leaching loss associated with application at the conventional rate. Recovery of residual N in the soil profile by succeeding crops was less than 7.5% of the applied N. For N120, total soil N balance was negative; however, there was still considerable mineral N （NH4^＋-N and NO3^--N） in the soil profile after harvest. Therefore, N120 could be considered ngronomically acceptable in the short run, but for long-term sustainability, the N rate should be recommended based on a soil mineral N test and a plant tissue nitrate test to maintain the soil fertility.