滴灌施肥灌溉的水氮运移数学模拟及试验验证

基于土壤水分运动的动力学方程和溶质运移的对流-弥散方程，建立了不同土壤中地表滴灌施硝酸铵（NH4NO3）时水分和硝态氮运移的数学模型及边界条件。利用商业化软件HYDRUS-2D对模型进行了求解。为了验证所建立的模型，分别在壤土和砂土两种土壤上进行了不同滴头流量、灌水量和肥液浓度下的湿润距离、土壤含水率和硝态氮分布试验。模拟结果与试验数据的对比表明，利用HYDRUS-2D求解所建立的模型得到的湿润距离随时问的变化过程、土壤含水率和硝态氮分布与实测值吻合良好。因此，HYDRUS-2D软件可以作为预测滴灌施肥灌溉条件下水分和氮素在土壤中运移的有效工具。     

Simulation of water and nitrogen dynamics in soils during wastewater applications by using a finite-element model

A mathematical model was developed to simulate water movement, mass transport, and nitrogen transformations in soils during wastewater applications. The model is one-dimensional and based on the Galerkin finite-element method. The submodel of mass transport of nitrogen incorporates the convection-dispersion processes of ammonium and nitrate nitrogen, nitrification, denitrification, ammonium exchange and uptake of ammonium and nitrate ions. The accuracy and validity of the proposed model was examined by comparison with an explicit-implicit finite-difference model results. The model was used for simulation of water and nitrogen dynamics during wastewater application in homogeneous and multi-layered soils under different N concentration, rate, duration and scheduling of application.     

不同氮源对黄花鸢尾净化富营养化水体的影响

利用水生植物床系统研究了不同氮源(硝酸盐、亚硝酸盐、铵盐)对黄花鸢尾(Iris pseudoacorus)去除水体氮磷营养盐效率的影响,同时对植物的生长量、水体中叶绿素a含量、黄花鸢尾对氮磷的吸收利用以及氮循环细菌的分布和氧化亚氮的通量进行了综合研究。结果表明:黄花鸢尾对硝酸盐氮具有优先选择性,而对氨氮的去除效果较差。从植物总氮、总磷吸收量来看,3种氮源中硝酸盐氮>亚硝酸盐氮>氨氮;从氮循环菌分布和N2O释放量来看,硝酸盐氮>氨氮>亚硝酸盐氮。一定范围内,植物对营养盐的吸收随营养盐浓度增加而增加,但水体中营养盐浓度过高则会抑制植物的生长,浓度为80 mg/L的硝酸盐氮,亚硝酸盐氮和氨氮都对黄花鸢尾生长有抑制作用,尤其是高浓度氨氮溶液中,植物的湿重明显减少,因此,黄花鸢尾更适宜治理硝酸盐污染的水体。     

Model-based optimisation of the biological performance of a sidestream MBR.

A model-based optimisation of the operation in view of the biological performance in terms of nitrogen (N) and phosphorus (P) removal of a pilot-scale side-stream MBR has been performed by means of a two-tier scenario analysis. The methodology uses two different scenario analyses to simulate the effect of three degrees of freedom in the MBR system: (1) DO set-point in the aerobic reactor, (2) sludge residence time and (3) internal recirculation rate. The scenarios are simulated using a calibrated ASM2d MBR model. Effluent quality, in terms of nitrate, ammonia and phosphate, is used to select the best scenario. It proved to be a compromise between nitrogen and phosphorus removal as these are linked. A 42% reduction in ammonium and a 32% reduction in nitrate concentration were achieved. Phosphate removal is partly sacrificed (39% increase) compared to the standard operation.     

Effect of didecyl dimethyl ammonium chloride on nitrate reduction in a mixed methanogenic culture.

The effect of the quaternary ammonium compound, didecyl dimethyl ammonium chloride (DDAC), on nitrate reduction was investigated at concentrations up to 100 mg/L in a batch assay using a mixed, mesophilic (35 degrees C) methanogenic culture. Glucose was used as the carbon and energy source and the initial nitrate concentration was 70 mg N/L. Dissimilatory nitrate reduction to ammonia (DNRA) and to dinitrogen (denitrification) were observed at DDAC concentrations up to 25 mg/L. At and above 50 mg DDAC/L, DNRA was inhibited and denitrification was incomplete resulting in accumulation of nitrous oxide. At DDAC concentrations above 10 mg/L, production of nitrous oxide, even transiently, resulted in complete, long-term inhibition of methanogenesis and accumulation of volatile fatty acids. Fermentation was inhibited at and above 75 mg DDAC/L. DDAC suppressed microbial growth and caused cell lysis at a concentration 50 mg/L or higher. Most of the added DDAC was adsorbed on the biomass. Over 96% of the added DDAC was recovered from all cultures at the end of the 100-days incubation period, indicating that DDAC did not degrade in the mixed methanogenic culture under the conditions of this study.     

考虑残留氮对非稳定流场硝态氮淋失贡献的传递函数模型

本文通过引入溶质迁移距离的概率密度函数的修正系数，将Jury等提出的模拟非稳定流条件下土壤保守溶质运移的传递函数模型理论扩展到考虑土壤剖面存在残留氮分布的土壤中，构造了一个能估算表施和残留氮对土壤硝态氮淋失动态贡献的传递函数模型。通过与野外地中渗透计实验资料的对比，表明该模型具有一定的仿真精度，模拟的土壤硝态氮累积淋失量的相对误差小于15%。     

考虑残留氮对非稳定流场硝态氮淋失贡献的传递函数模型Ⅰ.地中渗透计验证

本文通过引入溶质迁移距离的概率密度函数的修正系数，将Jury等提出的模拟非稳定流条件下土壤保守溶质运移的传递函数模型理论扩展到考虑土壤剖面存在残留氮分布的土壤中，构造了一个能估算表施和残留氮对土壤硝态氮淋失动态贡献的传递函数模型。通过与野外地中渗透计实验资料的对比，表明该模型具有一定的仿真精度，模拟的土壤硝态氮累积淋失量的相对误差小于15％。     

滴灌系统运行方式对砂壤土水氮分布影响的试验研究

以一种砂粒含量高达95%的砂土为对象，开展了滴灌施肥灌溉条件下，灌水器流量、灌水量和系统运行方式对水分、硝态氮和铵态氮分布影响的室内试验。灌水器流量的变化范围为0.5～2.0L/h，灌水量为6～7.7L；系统运行方式包括不同灌水和施肥次序组成的4种方案。研究结果表明，径向和垂直湿润距离随灌水量的增加呈幂函数关系增加；灌水量相同时，随灌水器流量的增大，灌水器周围的土壤含水率增加，垂直湿润距离减小，而径向湿润距离变化不大；灌水器流量一定时，垂直湿润距离随灌水量的增大而明显增加。对氮素分布的测试结果表明，硝态氮在湿润体边界存在累积现象；铵态氮在灌水器附近出现浓度高峰，且铵态氮集中在灌水器周围15cm范围内。滴灌施肥灌溉系统运行方式对硝态氮在土壤中的分布影响明显，建议采用最初用灌水施肥总时间的1/4灌水，再用1/2时间施肥，最后用1/4时间冲洗管道的运行方式，以便将施入土壤的氮素最大限度地保留在作物根区内，防止硝态氮淋失。     

Development of a new type of anaerobic digestion process equipped with the function of nitrogen removal.

In order to develop a new type of anaerobic digestion process equipped with a nitrogen removal function, denitrification of nitrate nitrogen (NO3-N) in anaerobic acidogenesis of organic fraction of municipal waste (OFMSW) was investigated by two semi-continuous reactors. Reactor 1 and Reactor 2 were fed by 3% and 7% of solids concentration of synthetic garbage, respectively. Generation of nitrogen gas (N2) and ammonium nitrogen (NH4-N) was simultaneously observed in the low load of nitrate (NO3-N) (below 0.68 g NO3-N/L). In Reactor 1, ammonium nitrogen generation decreased as the addition of nitrate increased. Finally, the increase of the addition of nitrate resulted in the increase of acetic acid production.     

层状土壤条件下地下滴灌水氮运移模型及应用

基于土壤水分运动的动力学方程和溶质运移的对流-弥散方程,考虑地下滴灌灌水器流量随时间的变化,建立了层状土壤地下滴灌施用硝酸铵(NH4NO3)条件下水氮运移的数学模型。利用均质砂土(S)、均质壤土(L)、上砂下壤(SL)和砂土夹层(LSL)四种土壤的试验数据对模型进行了验证。结果指出,考虑土壤中灌水器流量随时间变化可稍改善土壤含水率和硝态氮的模拟精度。利用验证后的数学模型研究了灌水器流量(1.1、1.75和2.6L/h)、灌水器与犁底层相对位置对地下滴灌水氮分布的影响,模拟结果表明灌水器流量对含水率分布的影响不明显,但灌水器流量的增大可明显增加20~40cm土层硝态氮含量;灌水器与犁底层相对位置对水氮分布影响显著,灌水器位于犁底层中(埋深25cm)土壤表层干土层较薄、水氮向下运移深度较小,有利于减小土壤蒸发和避免水氮淋失。     

A reactive nitrogen budget for Lake Michigan

The reactive (fixed) nitrogen (Nr) budget for Lake Michigan was estimated, making use of recent estimates of watershed and atmospheric nitrogen loads. Reactive N is considered to include nitrate, nitrite, ammonium, and organic N. The updated Nr load to Lake Michigan was approximately double the previous estimate from the Lake Michigan Mass Balance study for two reasons: 1) recent estimates of watershed loads were greater than previous estimates and 2) estimated atmospheric dry deposition and deposition of organic N were included in our budget. Atmospheric and watershed Nr loads were nearly equal. The estimated loss due to denitrification at the sediment surface was at least equal to, and possibly much greater than, the combined loss due to outflow and net sediment accumulation. Within the considerable uncertainty of the denitrification estimate, the budget was nearly balanced, which was consistent with the slow rate of accumulation of nitrate in Lake Michigan (~ 1%/yr). The updated loads were used to force the LM3-PP biogeochemical water quality model. Simulated water column concentrations of nitrate and organic nitrogen in the calibrated model were consistent with available observational data when denitrification was included at the sediment surface at a rate that is consistent with literature values. The model simulation confirmed that the estimated denitrification rate does not exceed the availability of settling organic N mass. Simulated increase (decrease) in nitrate concentration was sensitive to model parameters controlling supply of sediment organic N, highlighting the importance of internal processes, not only loads, in controlling accumulation of N.     

Spatial and Temporal Variation of Ammonium in Lake Superior

Many aspects of Lake Superior's nitrogen cycle are poorly described in spite of the fact that the lake's nitrate concentration has risen dramatically this past century. One important, yet underdescribed parameter is the concentration of ammonium. Here, we present data to resolve spatial and temporal variation along with vertical profiles of ammonium concentration in Lake Superior. Lake-wide average concentrations were low (0.21 μM, n =166) with considerable spatial and temporal variation. During the onset of summer, the western margin of the lake had higher average concentrations than open and eastern parts. Surface layer (<10 m) ammonium concentrations showed an increase from January to October. Relatively higher ammonium concentration in the near bottom waters at a number of sites during August indicated efflux from sediment to be an important process. Subsurface maxima near the thermocline were observed in late August and persisted until September-October suggesting that ammonium might be controlled by food web processes during warm, stratified conditions. The higher potential for ammonium uptake compared to external inputs suggested rapid turnover of ammonium in the lake.     

Effect of solid hold-up on nitrite accumulation in a biofilm reactor--molecular characterization of nitrifying communities.

Biological ammonium oxidation was carried out in two inverse turbulent bed reactors fed with synthetic mineral wastewater containing a high ammonium concentration (100 mg N-NH4+/L). Both reactors were started-up and operated in the same conditions except for the solid carrier concentration: the solid hold-up ratios applied, defined as the ratios of static to expanded bed height, were 0.1 and 0.3 in reactors R10 and R30 respectively. These two solid hold-up ratios generate different particle-to-particle collision frequencies and, therefore, detachment forces. The influence of solid hold-up on biofilm growth and nitrifying performance was studied from a macroscopic (i.e. nitrate and/or nitrite production) and microbiological point of view. After 60 days of operation, both reactors contained the same amount of biomass. However, R10 produced only nitrate while nitrite accumulated in R30. A comparison of microbial populations in the reactors showed that R10 contained both ammonium and nitrite oxidizing populations such as Nitrosomonas and Nitrospira, whereas in R30, ammonium oxidizing populations were much greater than those of nitrite oxidizers. The major ammonium-oxidizing organism was not the same in both reactors.     

影响反硝化除磷与厌氧氨氧化耦合的因素

氧对厌氧氨氧化菌有毒,但在颗粒污泥和生物膜中的厌氧氨氧化菌对氧有较高的耐受能力,并且聚磷菌能消耗影响氧氨氧化菌生长的氧。厌氧氨氧化菌的生长无需有机物的参与,聚磷菌释磷需要吸收有机物,少量有机物的加入对厌氧氨氧化菌的活性影响不大。亚硝酸盐是厌氧氨氧化菌氧化氨的电子受体,较高浓度的亚硝酸盐对反硝化聚磷有抑制作用,但合适浓度的亚硝酸盐(该浓度可以通过驯化来提高)可以作为反硝化聚磷菌吸磷的电子受体。厌氧氨氧化过程中有硝酸盐生成,反硝化聚磷菌能利用这部分硝酸盐。另外,两类菌都适宜于中温略偏碱性的环境。因此,通过创造同时对厌氧氨氧化菌和反硝化聚磷菌有利的微生态环境,发挥两者在脱氮除磷方面的协同耦合作用,达到高度脱氮除磷,是极有前景的废水厌氧(缺氧)处理研究方向。     

Leachate pre-treatment strategies before recirculation in landfill bioreactors.

Nitrified leachate recirculation represents a promising strategy for a more sustainable landfill management. Our objective was to determine the reactions involved in nitrate reduction in municipal solid waste batch biodegradation tests. Anaerobic digestion of waste in the three control reactors showed a good reproducibility. In two test reactors, nitrate was added at various moments of the waste degradation process. We observed that: (1) H2S concentration controlled the nitrate reduction pathway: above a certain threshold of H2S, dissimilatory nitrate reduction to ammonium (DNRA) replaced denitrification. (2) N2O/N2 ratio varied with the organic carbon concentration: the lower the easily biodegradable carbon concentration, the higher the N2O/N2 ratio. (3) N2 was consumed after denitrification. The possibility of a nitrogen fixation reaction in the presence of NH4 is discussed. Nitrified leachate recirculation during acidogenesis should be avoided because of higher H2S production which could induce DNRA.     

重庆市水利建筑工程预算定额小断面石方开挖炸药消耗定额测算研究

为提高重庆水利建筑工程预算定额质量,需要对小断面石方开挖乳化炸药消耗定额进行测算研究。通过对铵梯炸药和乳化炸药性能以及相关行业工程定额炸药耗量的分析,以重庆在建水利建筑工程小断面石方开挖炸药耗量实测数据为验证,拟合分析得到小断面石方开挖铵梯炸药与乳化炸药换算系数。结果显示,将工程中原来使用的铵梯炸药转化为现在使用的乳化炸药,定额耗量理论换算系数约为1.30;小断面石方开挖不同岩石级别的两种炸药耗量换算系数在1.22~1.69之间,断面面积越小,换算系数越大。本测算方法实现了小断面石方开挖定额数据由铵梯炸药向乳化炸药的转化,一定程度上解决了定额耗量比实际耗量显著偏小的问题,可为重庆水利建筑工程定额修订提供参考。     

Feasibility Assessment of Data-Driven Models in Predicting Pollution Trends of Omerli Lake,Turkey

Data-driven models are commonly used in a wide range of disciplines, including environmental engineering. To analyze Omerli Lake’s historic water pollution status, this study monitors data for dissolved oxygen, 5-day biochemical oxygen demand, ammonium nitrogen, nitrite nitrogen, nitrate nitrogen, and ortho phosphate. The quality of the lake water is assessed based on measurements of dissolved oxygen. The collected data are analyzed using regression analysis and artificial neural network models. The main goal of this paper is to reveal the best applicable data-driven model in order to gain forward-looking information regarding the dissolved oxygen level of the lake using other pollution parameters. In order to ascertain eutrophic status, total phosphorus loads for each year are represented on a Vollenweider diagram. Results designate an increasing risk of eutrophication for Omerli Lake in recent years. Results of the data-driven models show that the artificial neural networks model constitutes the best relationship between the dissolved oxygen and other parameters.     

Modeling response of nitrifying biofilm to inhibitory shock loads.

To study the response of nitrifying biofilm to inhibitory shock loads, a lab-scale nitrifying biofilm reactor was operated in ambient conditions. Shock loads of various concentrations of inhibitory compound were applied to the biofilm. Aniline was used as an inhibitory compound. The experimental results were utilized to develop a model for predicting the variation of effluent nitrate concentration from the biofilm reactor for given shock loads of aniline concentration and exposure time both in exposure as well as in recovery phase. Close agreement between model and experimental observation of bulk aniline concentration and effluent nitrate concentration was obtained which indicates the usefulness of the model to estimate bulk aniline concentration and to predict the response of inhibitory shock loads on nitrifying biofilm.     

生物有机肥与水分联合调控下稻田土壤氮素变化规律

为了探究生物有机肥和控制灌溉联合调控下稻田土壤氮素变化的特征和规律,开展了水稻小区种植试验。试验设置2种灌溉模式（常规淹灌（F）、控制灌溉（C））和3种施肥模式（全施化肥（A）、生物有机肥等氮替代15%化学氮肥（B）、生物有机肥等氮替代30%化学氮肥（C））,分析水稻生育期内土壤铵态氮与硝态氮含量的变化特征。试验表明：至水稻分蘖期时,相同灌溉模式下,配施生物有机肥处理的稻田土壤铵态氮含量均值均低于全施化肥处理,降幅为19.85%~48.78%,土壤硝态氮含量均值是生物有机肥等氮替代30%化学氮肥的处理低于全施化肥处理,降幅为15.35%~33.08%;而从水稻拔节期起,相同灌溉模式下配施生物有机肥处理的稻田土壤铵态氮平均含量比全施化肥处理增加了12.71%~56.26%,除FB处理硝态氮含量降低外其余配施生物有机肥处理的土壤硝态氮平均含量比全施化肥处理增加了19.21%~105.80%。控制灌溉的水稻全生育期土壤硝态氮含量显著高于常规淹灌（P＜0.05）,而土壤铵态氮含量则是常规淹灌高于控制灌溉。结果表明：生物有机肥配施化肥有利于水稻分蘖期后土壤铵态氮和硝态氮含量的积累,提升了稻田土壤氮素的养分累积,其中生物有机肥等氮替代15%化肥的效果较好。控制灌溉使得土壤硝态氮含量增加,同时也减少了土壤铵态氮的含量。综合考虑环境与经济效益,控制灌溉与生物有机肥等氮替代15%化肥的稻田水肥管理模式较好。     

基于水质综合指数法的亚热带水源型水库水质评价

为了解亚热带水源型水库——茜坑水库水质状况,基于2016年1月至2020年12月对水库pH值、高锰酸盐指数、五日生化需氧量、粪大肠菌群、氨氮、硝酸盐氮、总氮、总磷、硫酸盐、氯化物、氟化物、铁和锰等13个主要水质指标每月1次的监测数据,通过计算水质综合指数评价了水质状况,并通过多元线性回归优化水质综合指数模型。结果表明：水库水质整体较好,pH值和高锰酸盐指数受浮游植物繁殖影响,部分时段超标,总氮质量浓度偏高,总磷质量浓度和粪大肠菌群数部分时段较高,铁质量浓度的上升趋势应重点关注;表层监测难以全面体现分层对水质的影响,应增加垂向监测,全面掌握水库水质风险;利用由总磷、铁、高锰酸盐指数、氨氮和硝酸盐氮组成的主要污染指标水质综合指数模型可有效进行水质评价和管理。