Ammonia volatilization losses and balance from urea applied to rice on a paddy soil

Ammonia volatilization loss and 15N balance were studied in a rice field at three different stages after urea application in Taihu Lake area with a micrometeorological technique. Factors such as climate and the NH4+-N concentration in the field floodwater affecting ammonia loss were also investigated. Results show that the ammonia loss by volatilization accounted for 18.6%-38.7% of urea applied at different stages, the greatest loss took place when urea was applied at the tillering stage, the smallest at the ear bearing stage, and the intermediate loss at the basal stage. The greatest loss took place within 7 d following the fertilizer application. Ammonia volatilization losses at three fertilization stages were significantly correlated with the ammonium concentration in the field floodwater after the fertilizer was applied. 15N balance experiment indicated that the use efficiency of urea by rice plants ranged between 24.4% and 28.1%. At the early stage of rice growth, the fertilizer nitrogen use efficiency was rather low, only about 12%. The total amount of nitrogen lost from different fertilization stages in the rice field was 44.1%-54.4%, and the ammonia volatilization loss was 25.4%-33.3%. Reducing ammonia loss is an important treatment for improving N use efficiency.     

亚铁对水平潜流人工湿地反硝化作用的影响

亚铁离子可以作为电子供体参与反硝化作用,某些微生物可以通过氧化亚铁离子还原硝酸盐,从而去除污水中的硝态氮.本研究通过在潜流人工湿地中添加Fe2+,分析不同初始Fe2+浓度对反硝化过程的强化效果及不同C/N对Fe2+参与反硝化作用的影响.结果表明,Fe2+的添加可以显著提高人工湿地反硝化能力,进水NO-3-N为30 mg·L-1、C/N为2、水力停留时间为1 d,添加45 mg·L-1Fe2+的人工湿地中硝氮去除率可以提高24%;硝氮去除率随初始Fe2+浓度的增加而增加.C/N与初始Fe2+浓度对反硝化作用都具有显著影响且两者具有交互作用,碳源的存在可以促进Fe2+参与的反硝化作用.     

循环流化床二段燃烧燃煤过程中NO和N2O生成与控制研究

在小型石英循环流化床燃煤装置上,进行NO和N₂O生成与控制研究?研究结果表明:随着二次空气率的提高,NO明显下降,二次风口的位置高,NO的下降速率明显一些;随着二次空气率的提高,N₂O开始升高,但升高到一定程度后,随着二次空气率的提高,反而开始下降?此外,二次风口的位置高,N₂O随二次风变化曲线的上升段和下降段的斜率都略大?      

指数施肥对杉木苗期基质中微生物功能多样性的影响

为向轻型基质容器苗合理施肥,实现苗木养分精准调控提供理论依据,以杉木优良无性系"洋061"轻型基质容器苗为研究对象,设置7个施氮处理[对照(CK,0 mg/株)、常规集中施肥处理(CF1,40 mg/株)、常规分次施肥处理(CF,240 mg/株)、指数施肥(EF1,40 mg/株;EF2,80 mg/株;EF3,12...     

温度和C/N比对生物膜反硝化速率的影响

温度和C/N比是影响生物反硝化速率的2个重要参数,以反硝化生物膜为对象,研究了温度和C/N比对生物膜反硝化速率的影响.实验结果表明,生物膜在25 ℃下的反硝化速率要比13 ℃下的大;C/N比越高生物膜反硝化速率越大.     

N2:O emissions from a cultivated Andisol after application of nitrogen fertilizers with or without nitrification inhibitor under soil moisture regime

IntroductionNitrousoxide (N2 O)isoneoftheenvironmentallyimportanttracegases ,currentlyaccountingfor 2 %—4 %oftotalGreenhouseWarmingPotential (GWP ) .Itisalsoinvolvedinthedepletionofstratosphericozone .SoilhasbeenknownasthemajorsourceofN2 O ,accountingfor 6 5 %oftotalglobalemissions(Prather,1995 ) .Thus,reducingN2 Oemissionsfromsoilsisamaintaskfortheprotectionoftheglobalatmosphere .N2 Oisproducedastheresultofsoilmicrobialprocesses ,primarillybynitrification ,whentheoxidationhappensofNH+…     

Flocculant in wastewater affects dynamics of inorganic N and accelerates removal of phenanthrene and anthracene in soil

Recycling of municipal wastewater requires treatment with flocculants, such as polyacrylamide. It is unknown how polyacrylamide in sludge affects removal of polycyclic aromatic hydrocarbons (PAH) from soil. An alkaline-saline soil and an agricultural soil were contaminated with phenanthrene and anthracene. Sludge with or without polyacrylamide was added while emission of CO₂ and concentrations of NH₄⁺, NO₃⁻, NO₂⁻, phenanthrene and anthracene were monitored in an aerobic incubation experiment. Polyacrylamide in the sludge had no effect on the production of CO₂, but it reduced the concentration of NH₄⁺, increased the concentration of NO₃⁻ in the Acolman soil and NO₂⁻ in the Texcoco soil, and increased N mineralization compared to the soil amended with sludge without polyacrylamide. After 112 d, polyacrylamide accelerated the removal of anthracene from both soils and that of phenanthrene in the Acolman soil. It was found that polyacrylamide accelerated removal of phenanthrene and anthracene from soil.     

废水中氰化物测定方法的探讨

异烟酸—吡唑啉酮比色法检测水中氰化物的标准方法中使用的有机溶剂N,N-二甲基甲酰胺具有一定毒性且显色条件为水浴恒温,操作较繁琐。改进方法为用无水乙醇替代N,N-二甲基甲酰胺作为溶剂且显色条件为室内恒温。通过实验室分析,对比标准方法与改进方法对水中氰化物的测定。结果表明,改进方法的精密度和准确度均满足测定分析要求,同时避免了试剂的二次污染对人体的危害,又在一定分程度上简化了实验操作。     

保护地番茄养分利用及土壤氮素淋失

在施用不同复合肥料的条件下,对保护地蔬菜蕃茄对N、P、K养分的吸收利用及保护地条件下土壤的硝酸盐淋洗进行了研究,结果表明,复合肥的品种及施肥水平对番茄的产量影响不大,与CK相比番茄果实增产12．．7％－18．4％;复合肥N、P养分的当季利用率不足10％,而K素的当季利用率也不超出25％,传统的大水漫灌条件,蔬菜保护地土壤硝酸盐的淋洗状态相当严重,并有可能造成地下水的硝酸盐污染,长期过量施肥及大小漫灌等措施是造成土壤养分累积、硝酸盐淋洗严重、肥料利用率低的根本原因,图2表3参11     

土壤中氧化亚氮的产生及减少排放量的措施

氧化亚氮（N2O）是大气中的一种痕量气体,也是一种重要的温室效应气体,还可使臭氧层遭到破坏。大气中N2O浓度呈不断上升趋势,其上升与人类活动关系极大,对环境的潜在破坏性也愈加严重。土壤是N2O的重要产生源,土壤中的硝化作用和反硝化作用是N2O的主要生成过程。过量施用氮肥、含氮有机物燃烧、毁林开荒等人类活动对N2O释放增加的影响不容忽视。人类应采取各项可行的措施来减少N2O的释放量如提高氮肥利用效率,减少生物体燃烧,退耕还林和保护森林资源等。