Methode zur Bestimmung des Ammoniakstickstoffes in Gewässern

For the spectrophotometrical determination of ammonia in surface water the reaction with hypochlorite and thymol in alkaline solution is used. Compared with other techniques, expenditure is low, the reagents are stable for a long period of time and the reaction is little dependent on external conditions. In 2 cm cuvettes there can be determined 0.05… 0.5 mg/l ammonia nitrogen. Comparative investigations carried out at nine sites in the area of the lake Balaton have revealed concentrations of 0.2… 0.7 mg/l ammonia nitrogen.     

Degradation Pathway of the Photochemical Oxidation of Ethylenediaminetetraacetate (EDTA) in the UV/H2O2-process

The degradation pathway for the oxidation of EDTA in the UV/H₂O₂-process was investigated. In absence of iron ions, the mineralization of EDTA is dominated by the reaction of the HO-radicals generated by the photolysis of H₂O₂. The organic degradation products iminodiacetate (IMDA), glycinate, oxamate, glyoxylate, oxalate and formate, and the inorganic degradation products carbon dioxide, ammonia, nitrate, nitrite, and cyanate were found. In the presence of iron ions, photolytic decarboxylation processes inside the complex get an important role during degradation, and the organic degradation products ethylenediaminetriacetate (ED3A), ethylenediaminediacetate (EDDA), ethylenediaminemonoacetate (EDMA) were also found. By combining product studies with balances of carbon and nitrogen, the degradation pathway in the UV/H₂O₂-process could be elucidated. The degradation of EDTA was fast (k_deg = 0.012 s^–1), and no toxic degradation products were identified. Therefore, the process is well suited for the elimination of EDTA in water treatment.     

Atmospheric nitrogen deposition to the North Sea

The groups of nitrogen components that contribute most to the eutrophication of the sea are ammonia, nitrogen oxides and their respective reaction products. The emission of ammonia is mainly from animal husbandry, whereas the emission of nitrogen oxides is mainly from combustion processes. Ammonia reacts in the atmosphere to form particulate ammonium. Nitrogen oxides react to form nitric acid, nitrous acid, particulate nitrate and peroxyacetyl nitrate. The various nitrogen components have different physical and chemical properties. Therefore, their dry and wet deposition velocities differ. The dry deposition velocity of gas to the sea depends on its solubility, reactivity, concentration in seawater and the wind speed. The dry deposition velocity of a particle depends on its size and the wind speed. The wet removal rate is a function of meteorological conditions. For a gas it further depends on the solubility and reactivity of the gas. For a particle, it further depends on the particle's ability to act as a condensation nucleus for particles. The total deposition of ammonia and its reaction products to the North Sea is about 140 kt N a⁻¹. The total deposition of nitrogen oxides and their reaction products is about 200 kt N a⁻¹.     

Nitrifikation – Grundlagen des Stoffwechsels und Probleme bei der Nutzung von Ammoniakoxidanten

Nitrification – Fundamentals of the Metabolism and Problems at the Use of Ammonia Oxidizers From an ecological point of view, a great problem results from the release of increasing amounts of inorganic and organic nitrogen compounds. Apart from gaseous nitrogen compounds, such as the greenhouse gas N₂O, soluble nitrogen compounds such as ammonium cause difficulties. In recent years, great progress has been made regarding the reduction of the emission of sulfur and phosphorus compounds. Since there are no effective strategies for the decrease of nitrogen releases, the emission of such compounds has even been increasing. Therefore, great efforts are being made to eliminate the soluble nitrogen compounds in particular, for example in wastewater treatment plants. A decisive meaning befits the chemolithoautotrophic ammonia oxidizers. This review focuses on the ecological consequences of the release of ammonia in particular, the metabolism of the ammonia oxidizing microorganisms under consideration of the latest research results, and the problems that arise in the context of using these bacteria for the removal of ammonia.     

大型浅水湖泊沉积成岩模型不确定性与敏感性分析——以氮为例

随着太湖流域控源截污和面源整治的推行,底泥释放成为太湖不可忽视的污染源.本文基于EFDC模型构建太湖沉积成岩模型以动态模拟底泥释放过程,以氨氮和硝态氮为水质目标,采用拉丁超立方抽样抽取沉积成岩模型的18个参数进行不确定性分析,采用标准秩逐步回归法进行敏感性分析.结果表明：对于大型浅水湖泊,沉积物-水界面的硝化作用、反硝化作用和扩散过程对底泥氮的释放影响很大,太湖氮浓度的不确定性有明显的时空差异,并且受藻类生长影响;随藻类生长生化反应参数的敏感性逐渐减弱,动力参数的敏感性逐渐增强,氨氮的主要敏感参数为孔隙水扩散系数和最优硝化反应速率,贡献率分别是41.68%和37.82%,硝态氮的主要敏感参数为孔隙水扩散系数和表层反硝化作用反应速率,贡献率分别是29.15%和42.34%,这些参数的取值需予以着重考虑.本研究识别出太湖底泥氮释放的关键物化过程,为模型调参提供优先级并给出优化区间,对减小模型的不确定性、提高模型精度有参考意义,为定性指导大型浅水湖泊底泥释放的室内实验模拟提供依据.     

Characteristics of two novel cold- and salt-tolerant ammonia-oxidizing bacteria from Liaohe Estuarine Wetland

To achieve a better contaminant removal efficiency in a low-temperature and high-salt environment, two novel strains of cold- and salt-tolerant ammonia-oxidizing bacteria (AOB), i.e., Ochrobactrum sp. (HXN-1) and Aquamicrobium sp. (HXN-2), were isolated from the surface sediment of Liaohe Estuarine Wetland (LEW), China. The optimization of initial ammonia nitrogen concentration, pH, carbon–nitrogen ratio, and petroleum hydrocarbons (PHCs) to improve the ammonia-oxidation capacity of the two bacterial strains was studied. Both bacterial strains showed a high ammonia nitrogen removal rate of over 80% under a high salinity of 10‰. Even at a temperature as low as 15 °C, HXN-1 and HXN-2 could achieve an ammonia nitrogen removal rate of 53% and 62%, respectively. The cold- and salt-tolerant AOB in this study demonstrated a high potential for ammonia nitrogen removal from LEW.     

滇池表层沉积物铵态氮吸附特征

为研究滇池内源污染特征,2013年利用GIS软件针对滇池全湖布设36个采样点,采集表层沉积物,研究滇池表层沉积物铵态氮(NH_4+-N)吸附特征,同时分析沉积物的理化性质对NH_4+-N吸附特性的影响.结果表明:滇池表层沉积物对NH_4+-N的吸附量在前2 h之内呈增长趋势,吸附速率较大,之后沉积物对NH_4+-N的吸附量不随时间变化而变化,基本达到平衡,最大吸附速率均发生在0~5 min内;不同区域表层沉积物NH_4+-N最大吸附速率平均值表现为:外海南部湖心区外海北部草海,最大吸附量平均值表现为:湖心区外海南部外海北部草海,吸附效率平均值表现为:外海北部草海湖心区外海南部;沉积物对NH4+-N的吸附量与NH_4+-N的初始浓度大致呈线性关系,并且低浓度下表现出很好的吸附/解吸特征;滇池表层沉积物NH_4+-N的吸附解吸平衡浓度(ENC0)高于上覆水中NH_4+-N浓度,表明沉积物中NH_4+-N有向上覆水中释放的风险,沉积物在很长一段时间内起到水体污染"源"的作用;ENC0与沉积物中总氮、NH_4+-N含量呈显著正相关,本底吸附量和有机质总量呈显著负相关,沉积物吸附NH_4+-N主要受有机质的影响.     

The biogeochemistry of a manganese-rich Scottish sea loch: Implications for the study of anoxic nitrification

The anoxic oxidation of ammonia by manganese oxides is a newly recognised pathway for the production of N₂ in sedimentary environments, potentially contributing a significant loss of nitrogen from the world's oceans. Due to the complex recycling of redox species in marine sediments this process is difficult to discern in the natural environment, and is consequently poorly understood. The potential for anoxic nitrification coupled to manganese reduction was investigated through field research and laboratory incubation experiments. Field data from Loch Fyne, a manganese-rich site, did not provide conclusive evidence for anoxic nitrification, although minor accumulation of nitrate was observed in anoxic pore-waters. Incubation of Loch Fyne sediments showed anoxic nitrification to occur, with accumulation of both nitrate and nitrite coincident with removal of ammonia under anoxia, although these observations were not reproduced in repeat experiments. The laboratory evidence for anoxic nitrification confirms the reaction is possible in marine sediments; however, the wider significance of anoxic nitrification remains uncertain. Contrary to previous assumptions about anoxic nitrification, results suggest the reaction may not be dependent on total manganese concentrations and may be inhibited by conventional heterotrophic manganese reduction in manganese-rich sediments.     

Dynamische Modellierung des pH-Einflusses bei der Nitrifikation hochbelasteter Abwässer Dynamic Modelling of the pH Influence in Nitrification of Highly Concentrated Wastewater

Wastewater with high ammonia concentrations is produced by many industries, e.g. in the production of fertilizer and explosives and in the agricultural and food industry. A direct discharge into rivers and lakes has to be avoided: Oxidation of ammonia requires 4.56 g DO/g NH⁺₄-N and results in a decrease of dissolved oxygen concentration. Moreover, nitrate stimulates the proliferation of algae, with regard to the eutrophication of natural waters. For municipal wastewater with an ammonia concentration less than 50 mg/L NH⁺₄-N nitrification is a standard process. However, the removal of higher loaded industrial effluents still poses many questions. Recently, lab-scale and pilot-scale investigations show remarkable advances in the increase in nitrification efficiency and in the stabilization of the process. But because of changing flowrates and concentrations, the aid of advanced control algorithms is necessary. Some of the most important variables of biochemical reactors can be determined only with difficulty, at times only with off-line measurements. Model-aided measurement approaches try to determine these variables indirectly from easily measured variables. An experimentally-proved reactor model is required. Therefore, a dynamic model of nitrification in ideally mixed reactors is proposed based on mass balances for the components ammonia. nitrite, nitrate. dissolved oxygen DO, carbon dioxide, pH. nitrosomonas and nitrobacter. The biological reaction rates consider oxygen limitation and substrate inhibition. The process model presented is tested by lab scale experiments using an aerated stirred tank reactor and a fluidized bed reactor. Conformity between the predictions of the model and the observed data was positive. It has been shown that the nitrite oxidation by nitrobacter is the most sensible step in nitrification.     

硝态氮对库区水体藻类和细菌群落的影响

水体富营养化极易引起湖泊水库如藻类水华等水生态系统环境问题。氮素作为初级生产力的限制性生源要素之一,认识其在水华形成过程中潜在作用至关重要。本研究选取胶东半岛低碳高氮水库水体进行模拟实验,通过添加不同剂量硝态氮,探究高硝态氮输入对库区水体藻类和细菌群落结构的影响。结果表明:(1)当硝态氮作为唯一氮源,随着培养时间延长,硝态氮浓度显著下降,亚硝态氮和氨氮浓度逐渐升高,表明微藻和细菌共同作用可能将硝态氮转化为亚硝态氮和氨氮;(2)当硝态氮浓度为6 mg/L时,藻类叶绿素a浓度达到最高值,随着硝态氮浓度升高,叶绿素a浓度则会降低;(3)添加硝态氮后,蓝藻门成为优势藻类,绿藻门次之;变形菌门相对丰度显著升高。研究结果为低碳高氮类水体暴发蓝绿藻水华及有效防控提供理论依据和技术支撑。     

北京市北运河沉积物对氮、磷的吸附/解吸动力学特征

选取北运河土沟、榆林庄及和合站3个典型河道断面,进行河道0~60 cm深度沉积物对氨氮、磷酸盐的吸附/解吸批平衡静态试验研究,采用多种动力学模型分析北运河沉积物对氮、磷的吸附/解吸动力学特性,提出适用于北运河沉积物吸附/解吸特性的动力学模型,并对模型参数的主要影响因素进行探讨.结果表明:1)北运河典型断面各深度的沉积物对氨氮和磷酸盐的吸附/解吸过程总体呈现3个阶段:快反应阶段—慢反应阶段—平衡阶段;在0~0.5 h的快反应阶段可完成吸附或解吸总量的60%,且对氮、磷的吸附速率大于解吸速率.2)北运河各断面对氨氮与磷酸盐的平衡吸附量表现为S(榆林庄)S(土沟)S(和合站);对氨氮的平衡解吸量表现为S(土沟)S(榆林庄)S(和合站),对磷酸盐的平衡解吸量表现为S(和合站)S(土沟)S(榆林庄),沉积物对氨氮和磷酸盐的吸附以化学吸附为主,平衡吸附与解吸量随断面深度的增加而减小,0~20 cm表层沉积物对氮、磷的吸附能力较强.3)Lagergren二级动力学模型对各深度沉积物的吸附/解吸过程拟合最优,模型参数公式为k2=S-0.369max+0.163;qe=0.022 Smax+18.077 Kf+41.947.通过模拟得出在400 mg/L氮、磷浓度下吸附于沉积物中的氮、磷污染物会随着解吸过程释放52%~80%的氨氮和6%~42%的磷酸盐,可能不仅二次污染上覆水体,还随河水下渗从而对地下水质形成潜在污染风险.     

Global modelling study (GSM TIP) of the ionospheric effects of excited N2, convection and heat fluxes by comparison with EISCAT and satellite data for 31 July 1990

Near-earth plasma parameters were calculated using a global numerical self-consistent and time-dependent model of the thermosphere, ionosphere and protonosphere (GSM TIP). The model results are compared with experimental data of different origin, mainly EISCAT measurements and simultaneous satellite data (N_e and ion composition). Model runs with varying inputs of auroral FAC distributions, temperature of vibrationally excited nitrogen and photoelectron energy escape fluxes are used to make adjustments to the observations. The satellite data are obtained onboard Active and its subsatellite Magion –2 when they passed nearby the EISCAT station around 0325 and 1540 UT on 31 July 1990 at a height of about 2000 and 2200 km, respectively. A strong geomagnetic disturbance was observed two days before the period under study. Numerical calculations were performed with consideration of vibrationally excited nitrogen molecules for high solar-activity conditions. The results show good agreement between the incoherent-scatter radar measurements (N_e, T_e, T_i) and model calculations, taking into account the excited molecular nitrogen reaction rates. The comparison of model results of the thermospheric neutral wind shows finally a good agreement with the HWM93 empirical wind model.     

Preliminary15N studies on atmospheric nitrogenous trace gases

Preliminary nitrogen isotope data for ammonia from animal urine, fuel combustion, fertilizer use and fertilizer factories have been measured or estimated. It turns out that direct nitrogen isotope measurements of atmospheric ammonia at Jülich are in the expected range calculated from the ranges of different sources. For deposition of atmospheric ammonium in Jülich-rain a depletion in¹⁵N with respect to atmospheric ammonia has been found which is explained by isotope fractionations during rainout and washout. In correspondence with this fractionation model are nitrogen isotope data of rain-ammonium from coastal areas, which are enriched in¹⁵N due to the fact that sea water acts as a sink for atmospheric ammonia.For Jülich rain-nitrate a pronounced seasonal trend has been detected with lower¹⁵N data in spring and summer than in autumn and winter. This trend is interpreted by different nitrogen isotope data of anthropogenic and natural nitric oxides which have been measured or estimated from isotope fractionation effects during nitrification and denitrification reactions in soils. It should be possible to get better global estimations for anthropogenic and natural nitric oxides from nitrogen isotope measurements.     

东巢湖沉积物水界面氮、磷、氧迁移特征及意义

以东巢湖近城市湖湾沉积物为研究对象,在沉积物氮、磷营养盐分析的基础上,采用沉积物柱状芯样静态释放模拟法定量评估研究区域沉积物—水界面氨氮、溶解性活性磷酸盐营养盐释放潜力,利用微电极非损伤测定技术获得沉积物—水微界面溶解氧(DO)剖面分布及微界面DO消耗和扩散特征.结果表明:东巢湖近城市湖湾沉积物氮、磷污染物蓄积量较高,受TN、TP污染程度较重.沉积物内源氨氮、磷酸盐释放明显,平均释放速率分别达到32.44 mg/(m~2·d)和1.25mg/(m~2·d),区域内沉积物已成为水柱中氮、磷营养盐的污染源.研究区域上覆水体处于好氧状态,沉积物—水微界面平均DO穿透深度(OPD)达到5.3 mm,平均DO扩散通量为4.56 mmol/(m~2·d),表现出良好的DO扩散能力.沉积物内源氨氮和磷酸盐释放能力与表层沉积物TN/TP物质含量及沉积物—水微界面DO穿透深度有关,在沉积物氮、磷污染较重的情况下,DO穿透深度越低越有利于氮、磷污染物从沉积物向上覆水体释放.     

基于洱海水生态特征的流域最大日负荷总量控制

基于洱海水生态历史数据及现状资料,采用概率密度分布曲线法及水生生物基准相结合的方式计算洱海总氮(TN)、总磷(TP)、高锰酸盐指数(COD_(Mn))和氨氮(NH_3-N)的控制目标,目标值分别为0.36、0.026、4和0.28 mg/L.再根据该水质目标,得到洱海的最大日负荷(TMDL)总量.TMDL总量采用线性规划法计算,其中污染物响应系数矩阵通过MIKE 21二维水质模型计算所得.安全容余(MOS)则通过一阶误差分析法确定.经过一系列的计算,最终确定洱海的TMDL总量控制计划.计算结果表明,洱海TN、TP、COD_(Mn)和NH_3-N的TMDL总量分别为2005.989、149.671、19258.844和1348.119 kg/d,其MOS所占比例分别为6.152%、5.570%、4.380%和5.021%,表明洱海农业面源污染为该流域主要的污染形式,其允许最大排放量约占全部允许排放量的90%左右.     

The system iron-enstatite-water at high pressures and temperatures—formation of iron hydride and some geophysical implications

The system iron-enstatite-water was investigated at pressures around 5 GPa and at temperatures ranging from 1000 to 1200°C, using several different kinds of starting materials. Quenched samples showed the coexistence of iron, olivine and pyroxene. Synthesis of the Fe-containing olivine in the run products proves that a series of reactions, Fe + H₂O → FeH_x + FeO and FeO + MgSiO₃ → (Mg, Fe)₂SiO₄, have taken place. Spherical “balls of iron” were observed in the 1200°C run. This strongly indicates that the melting temperature of iron decreased by ～ 500 K by the possible dissolution of hydrogen. Following geophysical implications are derived from these experimental results. If water was retained in the hydrous minerals in the primordial material, the iron-water reaction is expected to occur throughout the core-formation process. The reaction product FeH_x will melt and then sink to form a proto-core and iron oxide will be dissolved in the Earth's mantle. The dissolution of hydrogen in the Earth's core is a natural consequence of the core-formation process.     

Modeling of aircraft exhaust emissions and infrared spectra for remote measurement of nitrogen oxides

Infrared (IR) molecular spectroscopy is proposed to perform remote measurements of NO_x concentrations in the exhaust plume and wake of aircraft. The computer model NIRATAM is applied to simulate the physical and chemical properties of the exhaust plume and to generate low resolution IR spectra and synthetical thermal images of the aircraft in its natural surroundings. High-resolution IR spectra of the plume, including atmospheric absorption and emission, are simulated using the molecular line-by-line radiation model FASCODE2. Simulated IR spectra of a Boeing 747–400 at cruising altitude for different axial and radial positions in the jet region of the exhaust plume are presented. A number of spectral lines of NO can be identified that can be discriminated from lines of other exhaust gases and the natural atmospheric background in the region around 5.2 µm. These lines can be used to determine NO concentration profiles in the plume. The possibility of measuring nitrogen dioxide NO₂ is also discussed briefly, although measurements turn out to be substantially less likely than those of NO. This feasibility study compiles fundamental data for the optical and radiometric design of an airborne Fourier transform spectrometer and the preparation of in-flight measurements for monitoring of aircraft pollutants.     

辽宁省大伙房水库及入库河流水质空间特征与河库水质关系

入库河流与水库存在空间上的连续性,河流污染物输入是水库水质恶化的主要原因,对大伙房水库及其入库支流61个采样点的水质状况进行调查,并运用聚类分析和主成分分析对大伙房水库及入库支流的水质空间特性和主要污染物进行分析.聚类分析显示,按照水质相似性将大伙房水库及入库支流水质可分为上游区、下游区和库区3个典型空间区域.分别对3个区域进行主成分分析,结果显示:入库支流上游区和下游区水质主要影响因素为氨氮、总氮和化学需氧量,库区影响水质的主要因素为温度、p H值、浊度、溶解氧、电导率、氨氮和总氮.对上游、下游和库区水质均有显著影响的因子为氨氮和总氮,上游区、下游区和库区氨氮浓度均值分别为0.06、0.10和0.19 mg/L,总氮浓度均值分别为0.13、0.16和0.26 mg/L.入库河流下游区对水库水质影响较大,受社河和浑河污染物输入的影响,大伙房水库水质在空间上呈现社河入库区水质优于浑河入库区水质.并且库区氨氮和总氮浓度均与距岸边距离呈负相关,溶解氧和p H值均与距入库口距离呈负相关,表明入库河流污染物输入和环库区面源污染均对大伙房水库水质产生一定影响.     

The planetary scale distribution of telluric currents and the effect of the equatorial electrojet: An investigation by canonical GDS

The planetary scale distribution of electrical currents in the Earth is still largely unknown. The role of the oceans for long period (hours to days) inducing electromagnetic fieldsB _e of external origin has been investigated by several authors, while the role of telluric current channelling, from the planetary viewpoint, is still far from a satisfactory understanding. Canonical geomagnetic depth sounding (GDS) analysis can yield locally a direction parallel to the strike of a telluric current density flowing in a region around the recording site and which also has the property of being the most relevant source for the internal origin fieldB _i observed at the given site at the given frequency. The use of such local information from 64 geomagnetic observatories is discussed here in a study to infer evidences of (a) the role of the polarization properties ofB _e and (b) the role of the telluric current channelling within conductivity anomalies relevant to the planetary scale circuitry. The results show clear evidence of the influence of the equatorial electrojet on the polarization ofB _e in a latitudinal band between ±(15°–20°) latitude. There is also evidence that theB _e associated with the equatorial electrojet produces telluric currents which flow at a much shallower depth than the skin depth to be expected in the case of a plane Earth. This implies that the Parkinson planes in these regions reflect the conductivity structure underground more than the polarization ofB _e due to the equatorial electrojet. Further, it clearly appears that some regular planetary scale pattern of telluric currents plays a more significant role than current channelling within some conductivity anomalies of fixed strike close to some geomagnetic observatories. Finally, the number of observatories used in this study appears to be insufficient to deduce any information concerning a seasonal evolution of the telluric current pattern on a planetary scale.     

Untersuchungen zum Schadstoffpotential von Wasserwerksschlämmen

Investigation on the Pollution Potential of Waterworks Sludges Several contaminated sludges from water treatment plants with known or estimated concentrations of trace elements were investigated for their leaching characteristics and long-term stability using standard and advanced test procedures. Potentially hazardous elements in the sludge are zinc, nickel, and arsenic with concentrations of up to 1.2 g/kg dry matter (mass). Preliminary sorption tests with synthetic sludge components like iron hydroxide, manganese oxide, silicate clay minerals, and chitine powder as a model organic component showed that Cu is associated with the organic phase wheras arsenic is predominantly bound to the iron oxide minerals. The recently suggested pH_stat test procedure was used to assess the leaching characteristics of metals at typical pH values. This procedure was compared with the DEV-S4 test, the current standard test in Germany, consisting of a simple lixiviation of the solids with water, without pH control. The pH_stat test yields results which are much better to interprete than those obtained by the DEV-S4 procedure. The iron and manganese sludges are well buffered against changes in pH and redox potential so that low pH values and/or reducing conditions can hardly occur. Thus, in deposited material a sudden leaching of heavy metals is unlikely and due to the presence of iron and manganese oxides the pentavalent arsenic is protected against conversion into the highly mobile trivalent form at neutral to low pH. Co-deposition with reducing organic matter and alkaline stabilisation material or waste (like fly ash) could influence the binding properties and should be strictly avoided.