碱性过硫酸钾法测定水质总氮的影响因素

碱性过硫酸钾氧化法测定总氮时经常出现空白值异常高的现象,本文通过实验研究发现:实验室环境、过硫酸钾的纯度、碱性过硫酸钾溶液存放时间、消解时间、消解温度等因素对测定均有影响.本文对这些因素进行了实验分析并提出了改进意见,对鄱阳湖水样进行了加标回收实验,结果令人满意.     

连续流动分析法测定不同冰冻时间的淡水总氮浓度

采用AA3连续流动元素分析仪对不同冰冻时间的标准水样和自然水样的总氮含量进行了测定。结果表明.供试水样在-20℃条件下冰冻30d的总氮浓度稳定,但自然水样较标准水样波动幅度大。     

多量程原位水质总磷总氮一体式在线监测仪

针对地表水和城镇污水对于总磷(TP)总氮(TN)联合测定的需求,基于国标法提出了联合测定原理,利用顺序注射技术和微控技术建立水质总磷总氮多量程在线监测系统,完成了TP和TN的测定。总磷的测定量程分为0～1.2,1.2～2.5,2.5～5μg·mL~(-1);总氮测定量程分为0～10,10～20,20～40μg·mL~(-1)。测定范围涵盖地表水环境I～V类水和城镇污水处理厂排放标准中总磷、总氮的标准限值。利用交替最小二乘拟合算法建立了总磷与总氮测定的回归模型。实验结果表明,其校正决定系数≥0.996 4,最低检出限分别为0.01μg·mL~(-1)和0.05μg·mL~(-1),重复性相对标准偏差(RSD)分别为1.36%～3.84%、0.78%～3.69%,贵州七大水库实际水样数据比对中,总磷相对误差≤±3.7838%,总氮相对误差≤±3.69%。系统运行稳定,可以精准、高效地分析不同地表水样的总磷总氮,为环境保护和污水排放提供了技术支持,尤其适用于实验室、站房式、便携式在线水质监测。     

测定总氮时影响空白吸光值的因素

针对GB 11894-89测定污水中总氮空白值偏高的情况,分析了碱性过硫酸钾本身以及纯度的影响、消解量、消解温度和时间、去离子水纯度、玻璃器皿的洁净度、碱性过硫酸钾存储时间、环境因素等影响因素,找出了实验出现问题的原因,并进行了校正.     

氢化物发生-原子荧光光谱法测定地表水中锑方法探讨

锑在水中有不同的价态,在弱酸性或中性溶液中易水解,给原子荧光光谱法检测锑带来一定影响.本文通过对地表水进行消解和不消解的比对分析,探讨检测过程中的影响因素,改进和完善原子荧光光谱法测定水样中锑的方法,使其检测结果更准确地反映水样中锑及化合物的浓度.     

火焰原子吸收光谱法测定水中铁的测量不确定度评定

通过对影响测定结果的不确定度因素的分析和量化,评价了火焰原子吸收光谱法测定水样中铁的不确定度。计算得水中铁含量测定结果的扩展不确定度为0.015mg/L(veff=17)。     

流动注射在线消解测定水中总氮

研究了流动注射在线消解测定水中总氮的自动分析方法。方法基于使用电热和紫外在碱性过硫酸钾体系中消解样品,有机形态和无机形态的氮都被氧化为硝酸盐氮,消解效率为93.0%—108.5%。硝酸盐通过镀铜的镉柱还原为亚硝酸盐,亚硝酸盐与4-对氨基苯磺酰胺、N-（1-萘基）乙二胺盐酸盐形成偶氮染料,在540nm处进行测定。方法的线性范围为20.0—2000.0μg.L-1（r≥0.9995）,检出限为8.3μg.L-1,相对标准偏差为0.8%—1.6%;样品测定频率为35样/h,地表水、地下水、自来水等实际水样的加标回收率为95.9%—107.3%。对于污水样品中的总氮测定FIA与国标方法GB 11894-89对比,无显著差异。     

氢化物发生-原子荧光光谱法对水中总硒含量测试方法改进研究

为探寻简单可靠的水中硒测试方法,在采用国标中氢化物发生-原子荧光光谱法测定水样中的硒含量时,对影响水中硒消解的因素如消解温度和盐酸用量等进行了比较,并且确定了一种简易可行的新方法,即水样在100℃消解时加入3mL盐酸。采用3,6和10μg.L-1硒标液测定了方法的精密度和准确度,测试的结果分别是2.96,5.43和9.66μg.L-1,回收率在90.50%～98.67%。同时,用不同方法测试了29个水样中的硒含量,国标中氢化物发生-原子荧光光谱法测定水样中的硒含量的标样的误差为8.95%～25.46%,新方法测定标样的误差为1.33%～3.40%。新方法相对于中华人民共和国标准GB/T 5750.6-2006水中硒测试方法而言,具有操作过程简单、易控制和可靠性强、经济等特点。     

水杨酸功能化聚苯乙烯包覆硅胶复合微粒对银的分离富集性能研究

制备了水杨酸功能化聚苯乙烯包覆硅胶复合微粒,填充微柱后,测定了微柱的穿透曲线和洗脱曲线。将微柱用于低浓度Ag（I）的分离富集测定,研究了各影响因素,优化了实验条件。测定Ag（I）的线性范围为0.020—0.50μg/mL。方法可用于水样中痕量银的测定。     

分散液液微萃取-分光光度法测定环境水样中孔雀石绿

建立了简便、快速、有效的分散液液微萃取-分光光度法测定环境水样中孔雀石绿的分析方法。对萃取剂、分散剂的种类和体积、萃取时间、离心时间、盐浓度等影响萃取效率的因素进行了优化。在优化的萃取条件下,方法的线性范围为8—1000μg/L（r=0.9992）,相对标准偏差（RSD）为4.1%（C=100μg/L,n=6）,检出限为4.20μg/L。对3种实际水样中的孔雀石绿进行测定,加标回收率在74.7%—108.2%之间（n=5）。方法适用于环境水样中的痕量孔雀石绿的检测。     

Magnetic nanoparticles as sorbent for preconcentration and determination of lead in fish and water samples

In the present work, a procedure for the preconcentration and determination of lead trace amounts of lead in fish species and water samples by graphite furnace atomic absorption spectrometry (GF AAS) is proposed, which is based on the batch solid phase extraction of lead ions by modified magnetic nanoparticles. An optimization process was performed using two-level fractional factorial designs (2^4-1) and a Box–Behnken matrix. Four variables (pH of solution, nanoparticles mass, morin mass, and shaking time) were regarded as factors in the optimization. The detection limit of the proposed method was found to be 81.0 ng/l. Six samples of fish and three samples of water (tap, river, and lake) were analyzed for lead. The lead contents ranged in fish from 0.013 to 0.038 μg/g and in water from 7.1 to 9.0 μg/l.     

Using environmental isotopes 2H and 18O for identification of infiltration processes in floodplain ecosystems of the River Elbe

We examined a floodplain area in the middle section of the river Elbe Valley with regard to hydrogeological and hydrological processes using isotopic methods. Over two years, river water and groundwater have been analysed for temporal and spatial chemical and isotopic (delta2H and delta18O) changes. By these methods we assessed the flow dynamics of the river-groundwater infiltration system. At low and mean river stages there is a general hydraulic gradient from the higher areas at the margin of the valley towards the floodplain. During floods river water infiltrates into the adjacent aquifer not primarily through the river banks but first through surface water inflow from north to south, via depressions and gullies from the back of the floodplain. The early stage of river water infiltration is characterized by a sharp decrease in conductivity and in concentrations of SO4(2-) and Cl- in the hydraulically connected shallow aquifer. delta2H and delta18O values show a similar tendency. We observed a significant minimum in stable isotope ratios during the flood in March 1999. Using a simple mixing equation it was calculated that the groundwater in the upper, shallow aquifer consists of around 70% river water in the transition zone (well 13) during flooding.     

Use of isotopes to study floodplain wetland and river flow interaction in the White Volta River basin,Ghana

Floodplain wetlands influence the timing and magnitude of stream responses to rainfall. In managing and sustaining the level of water resource usage in any river catchment as well as when modelling hydrological processes, it is essential that the role of floodplain wetlands in stream flows is recognised and understood. Existing studies on hydrology within the Volta River basin have not adequately represented the variability of wetland hydrological processes and their contribution to the sustenance of river flow. In order to quantify the extent of floodwater storage within riparian wetlands and their contribution to subsequent river discharges, a series of complementary studies were conducted by utilising stable isotopes, physical monitoring of groundwater levels and numerical modelling. The water samples were collected near Pwalugu on the White Volta River and at three wetland sites adjacent to the river using the grab sampling technique. These were analysed for ¹⁸O and ²H. The analysis provided an estimate of the contribution of pre-event water to overall stream flow. In addition, the variation in the isotopic composition in the river and wetland water samples, respectively, revealed the pattern of flow and exchange of water between the wetlands and the main river system.     

基于固有光学量的高光谱数据反演城市河网水质

水体辐射传输模型是水体光谱特性分析的理论基础,水体固有光学量由水体组成决定,与水体表面光场无关。基于统计的半经验算法虽然能获取指定区域水质参数反演结果,但是缺乏物理意义;基于生物光学模型的分析算法,针对城市河网内陆Ⅱ类水体光学特性复杂、空间分布异质性强、水体细小、流动性大等特点,利用高光谱数据,研究基于固有光学量的城市河网水质参数反演模型,对内陆城市浑浊水体光谱特性研究具有重大意义。提出了适用于内陆城市河网水体的改进QAA算法,以获取水体固有光学量,改进包括后向散射估计模型调整和参考波段优化两个方面;计算参考波段总吸收系数、颗粒物后向散射系数等固有光学量,得到浮游植物吸收系数和剔除纯水吸收系数;对浮游植物吸收系数最优波段比值与叶绿素a浓度进行线性回归分析,构建叶绿素a水质浓度反演模型,对剔除纯水吸收系数最优波段比值与悬浮物浓度线性回归分析,构建悬浮物水质浓度反演模型。针对内陆河网Ⅱ类水体,以典型的河网城市嘉兴市为研究区域,获取了研究区域航空高光谱数据,以及水质采样化验数据和水面以上光谱数据等地面准同步测量数据;利用QAA算法和IIMIW算法对实测水面以上光谱进行固有光学量反演,对比分析两个算法并结合城市河网水体特点,提出改进QAA算法;利用改进的QAA算法实现了研究区域水体的固有光学量反演,基于反演的水体固有光学量建立了叶绿素a浓度和悬浮物浓度两项水色参数定量反演模型,反演模型决定系数R2分别为0.64和0.71;并用航空高光谱数据同步区域的4个地面样点实测数据,对反演结果进行验证分析。通过水质参数浓度反演值与实测值的对比,叶绿素a和悬浮物水质浓度反演的平均相对误差分别为9.2%和9.4%,反演得到的叶绿素a和悬浮物浓度分布图,也与城市河网的特点和实际情况相符,为城市河网水质监测提供方法和模型参考。     

基于物联网的城市河道酸碱度远程检测系统的设计

随着城市经济的发展,城市河道水环境受到了严重的污染和破坏,其中水质的酸碱度是水质污染的一个重要指标。由于城市河道水质污染的不确定性,一套能够在野外无人看管的环境下,多节点多范围对河道水质酸碱度实时检测系统成为一种需求。系统中每个采集节点连有pH传感器,采集的pH值数据通过Zigbee模块传给基站,基站将每个节点的数据与时间和地点信息绑定存储到云端数据库。管理人员可以通过网页随时随地了解当前各区域的水质酸碱度情况,如一旦水质出现污染,管理人员可以通过后台了解水质污染的扩散情况和污染源头,可以及时采取措施降低损失。该系统的运用与传统的人工现场取样带回实验室分析的方法相比,不但极大的提高了预警能力而且还大幅降低人力成本。     

Flame Emission Measurement of Alkali and Alkali Earth Metals Using Atomic Absorption Apparatus (2) Determination of Na in River Water

Flame Emission measurement of Na using an ordinary atomic absorption apparatus is performed in order to determine the concentration of Na in the surface water of the river Izumi, which is used for the irrigation of rice field in summer time.

The effect of acids and K on Na emission are studied and found to be eliminated when the proper conditions and positions of the flame is chosen. The recovery ratio of 8 ppm and 200 ppm Na added to the well water and river water, respectively, are found to be within 92–105%. This method can be applied to the routine analysis of Na in river water samples.     

Soft X-ray microscopy and spectroscopy at the molecular environmental science beamline at the Advanced Light Source

We present examples of the application of synchrotron-based spectroscopies and microscopies to environmentally relevant samples. The experiments were performed at the molecular environmental science beamline (11.0.2) at the Advanced Light Source, Lawrence Berkeley National Laboratory. Examples range from the study of water monolayers on Pt(1 1 1) single crystal surfaces using X-ray emission spectroscopy and the examination of alkali halide solution/water vapor interfaces using ambient pressure photoemission spectroscopy, to the investigation of actinides, river water biofilms, Al-containing colloids and mineral–bacteria suspensions using scanning transmission X-ray spectromicroscopy. The results of our experiments show that spectroscopy and microscopy in the soft X-ray energy range are excellent tools for the investigation of environmentally relevant samples under realistic conditions, i.e., with water or water vapor present at ambient temperature.     

水中亚硝酸盐氮测定条件优化

采用紫外分光光度法对嘉陵江水中亚硝酸盐氮的含量进行定量分析。优化测定条件,得最佳测定条件为：氢氧化锌处理水样,1g/L碱性品红2.00mL,反应时间20min。测得水样中亚硝酸盐氮平均含量为2.875mg/L。该方法试剂无毒,操作简便快捷,干扰小,适合水质中亚硝酸盐氮的定量分析。     

水资源时延控制模型及研究

水资源系统是由水资源自然分系统和人工分系统合成的复杂大系统.把设计修建的水资源工程视作安装于自然系统上的一个控制器,同时考虑当前状态量与时延量的制约关系.首次建立了一个由流域、湖泊及引水工程等组成的非线性水资源时延控制数学模型,讨论了该类系统的稳定性、最优控制、次优控制等理论,最后给出次优控制的数值计算及结果.     

Entropy-Based Shear Stress Distribution in Open Channel for All Types of Flow Using Experimental Data

Korean river design standards set general design standards for rivers and river-related projects in Korea, which systematize the technologies and methods involved in river-related projects. This includes measurement methods for parts necessary for river design, but does not include information on shear stress. Shear stress is one of the factors necessary for river design and operation. Shear stress is one of the most important hydraulic factors used in the fields of water, especially for artificial channel design. Shear stress is calculated from the frictional force caused by viscosity and fluctuating fluid velocity. Current methods are based on past calculations, but factors such as boundary shear stress or energy gradient are difficult to actually measure or estimate. The point velocity throughout the entire cross-section is needed to calculate the velocity gradient. In other words, the current Korean river design standards use tractive force and critical tractive force instead of shear stress because it is more difficult to calculate the shear stress in the current method. However, it is difficult to calculate the exact value due to the limitations of the formula to obtain the river factor called the tractive force. In addition, tractive force has limitations that use an empirically identified base value for use in practice. This paper focuses on the modeling of shear-stress distribution in open channel turbulent flow using entropy theory. In addition, this study suggests a shear stress distribution formula, which can easily be used in practice after calculating the river-specific factor T. The tractive force and critical tractive force in the Korean river design standards should be modified by the shear stress obtained by the proposed shear stress distribution method. The present study therefore focuses on the modeling of shear stress distribution in an open channel turbulent flow using entropy theory. The shear stress distribution model is tested using a wide range of forty-two experimental runs collected from the literature. Then, an error analysis is performed to further evaluate the accuracy of the proposed model. The results reveal a correlation coefficient of approximately 0.95–0.99, indicating that the proposed method can estimate shear-stress distribution accurately. Based on this, the results of the distribution of shear stress after calculating the river-specific factors show a correlation coefficient of about 0.86 to 0.98, which suggests that the equation can be applied in practice.