N2O emissions from different cropping systems and from aerated,nitrifying and denitrifying tanks of a municipal waste water treatment plant

Nitrous oxide emissions, nitrate, water-soluble carbon and biological O₂ demand (BOD₅) were quantified in different cropping systems fertilized with varying amounts of nitrogen (clayey loam, October 1991 to May 1992), in an aerated tank (March 1993 to March 1994), and in the nitrification-denitrification unit (March to July 1994) of a municipal waste water treatment plant. In addition, the N₂O present in the soil body at different depths was determined (February to July 1994). N₂O was emitted by all cropping systems (mean releases 0.13–0.35 mg N₂O m^-2 h^-1), and all the units of the domestic waste water treatment plant (aerated tank 0–6.2 mg N₂O m^-2 h^-1, nitrification tank 0–204,3 mg N₂O m^-2, h^-1, denitrifying unit 0–2.2 mg N₂O m^-2 h^-1). During the N₂O-sampling periods estimated amounts of 0.9, 1.5, 2.4 and 1.4 kg N₂O–N ha^-1, respectively, were released by the cropping systems. The aerated, nitrifying and denitrifying tanks of the municipal waste water treatment plant released mean amounts of 9.1, 71.6 and 1.8 g N₂O–N m^-2, respectively, during the sampling periods.The N₂O emission were significantly positively correlated with nitrate concentrations in the field plots which received no N fertilizer and with the nitrogen content of the aerated sludge tank that received almost exclusively N in the form of NH ₄ ⁺ . Available carbon, in contrast, was significantly negatively correlated with the N₂O emitted in the soil fertilized with 80 kg N ha^-1 year. The significant negative correlation between the emitted N₂O and the carbon to nitrate ratio indicates that the lower the carbon to nitrate ratio the higher the amount of N₂O released. Increasing N₂O emissions seem to occur at electron donorto-acceptor ratios (C_H2_O or BOD₅-to-nitrate ratios) below 50 in the cropping systems and below 1200–1400 in the waste water treatment plant. The trapped N₂O in the soil body down to a depth of 90 cm demonstrates that agricultural production systems seem to contain a considerable pool of N₂O which may be reduced to N₂ on its way to the atmosphere, which may be transported to other environments or which may be released at sometime in the future.Dedicated to Professor J.C.G. Ottow on the occasion of his 60th birthday     

城市污水处理厂污泥处理处置及利用浅析

污泥的处理处置与利用是当今面临的重要问题.文章分析了我国污泥处理的现状,介绍了污泥的组成、性质,讨论了污泥处理处置的各种方法及利用方式,最终得出了污泥的材料化利用是污泥处置的理想途径的结论.     

内浮顶罐下沉浮盘的改造

为提高内浮顶罐浮盘的抗沉能力，将钢制浮盘改造为铝质浮盘，叙述了具体的施工步骤及实际应用中应注意的事项。实践证明此改造方案效果较佳，可供借鉴。     

长江中下游(湖北段)低丘滩地的综合治理与开发

选择鄂州，石首，松滋，浠水4县市作为试验点，进行了低丘和滩地的立地划分，开发模式，适地适树，抑螺植物选择及良种壮苗快繁等技术的研究。并将滩地扬树优良无性系选育截杆扦 插造林等技术组装成扬树产业化技术体系。通过本项研究技术成果的应用，极大地改善了长江中下游（湖北段）低丘滩地的生态环境，并促进了区域经济的可持续发展，同时该技术成果还为整个长江中下游低丘滩地的综合治理与开发提供了科学数据和理论依据。     

城市污泥处理处置及资源化研究进展

我国是一个经济基础较为薄弱、可耕地有限的农业大国,而污泥中富含植物生长必需的有机质、腐殖质和矿质元素,本文首先介绍了将污泥作为栽培基质部分或全部替代土壤,将污泥制成复合或生物复合肥料与无机或有机基质混配为复合基质等的可行性;然后指出使污泥处置与污泥稳定化、减量化、无害化及资源化相结合将成为解决城市污泥问题的最终出路。     

呼和浩特市城市垃圾管理决策系统研究

本文在总结国内外对城市垃圾处理技术发展情况的基础上，根据呼和浩特市垃圾处理的现状及其中存在的问题．以visualj^ 6．0应用程序为核心，结合Photoshop、Access，Fxbase和FIaSh等软件，构建了呼和浩特市垃圾管理决策系统平台。该平台包括垃圾处理、垃圾现状、垃圾预测及系统信息4个模块．并且通过初步运行表明，本系统可以实现基于垃圾产生量、处理技术、处理方法的较为理想的资源配置决策。     

光合细菌研究概况及其应用进展

对光合细菌的分类，分布，结构成分，生理代谢及营养和环境条件做了介绍，对光合细菌的应用做了系统的概述。     

某拱顶油罐基础沉陷的修复与试水

通过对某泵站一座1×10~4m~3拱顶油罐基础沉陷修复方案和施工,及充水试验情况的介绍,说明此次油罐基础沉陷处理的方法得当,并收到良好的效果。此次储罐基础沉陷的处理方法简单,只切割底板,处理下沉地基省时、省力、节省费用。     

环舱式内浮顶油罐倾斜的处理

１４２号罐更新为环舱式内浮顶油罐后，罐体发生倾斜，由于浮盘较重，因此，现场分步正油罐罐体，先使倾斜一边的浮盘支柱落到罐的基础上，用空气吹砂法砂法矫正油罐主体；再用千斤顶顶起浮盘，修补罐底，然后试水，合格后恢复油罐附件，纠斜收到了预期效果。     

农业气象服务信息的分布式处理

叙述了使用运行于计算机网络上的应用气象信息服务系统远程分布式采集、编制和发布农业气象服务信息的方法，阐述了确保应用气象信息分布式处理效果的措施。