永定河冲洪积扇地下水中硝酸盐来源的同位素识别

硝酸盐(NO_3~-)是北京地下水的主要污染物之一。本文分析了永定河冲积扇不同部位第四系地下水的水化学和氮、氧同位素特征,识别了地下水中NO_3~-的主要污染源,并定量评价了各种源的贡献。研究区地下水的NO_3~--N浓度介于1.32~37.44 mg/L,80%的地下水样NO_3~--N浓度超过我国《生活饮用水卫生标准》(20 mg/L)。地下水的δ15N-NO_3~-值介于+9.38‰~+16.96‰,均值12.87‰,δ18O-NO_3~-值介于+3.13‰~+21.18‰,均值+10.39‰,结合反硝化作用的识别,推断地下水中NO_3~-主要来自粪肥,部分来自NO_3~-化肥和大气降水。采用氮、氧同位素和物质平衡混合模型定量评价表明,粪肥对地下水NO_3~-的贡献为58%~81%,据此提出了保护和改善地下水水质的建议。     

氮元素降解随流速的变化规律研究

本文介绍了采用循环环境水槽试验对流速对氮元素降解过程的影响进行的研究。研究中,分别监测了不同流速条件下水体的氨氮、硝酸盐(NO_3~--N)、亚硝酸盐(NO_2~--N)浓度随时间的变化过程,并分析了pH随流速变化对氮元素主要降解过程的影响。结果表明:实验水体pH主要受氮元素迁移转化的影响,其值的变化与氨氮、硝酸盐(NO_3~--N)、亚硝酸盐(NO_2~--N)的浓度变化显著性相关,其与流速同样关系紧密,无论是氨化反应占主导阶段,还是硝化、反硝化反应占主导的阶段,均是流速越大,pH越高。     

氢氧稳定同位素对东平湖枯水期水环境的指示作用

为掌握东平湖枯水期水环境质量,采集氢氧稳定同位素样品分析了氢氧同位素分布、氘盈余(d值)和富营养化状况,揭示了枯水期蒸发作用和人为因素对湖泊水质的影响,结果表明:(1)单因子评价法反映出东平湖枯水期富营养化现象严重,水体中COD、TN和TP含量平均值分别为16.92mg/L、0.80mg/L和0.31mg/L,接近重富营养化;(2)枯水期δD和δ18 O呈现出从湖区的东南向西北逐渐增加的规律,而氘盈余值则表现出与δD和δ18 O比值相反的空间分布。湖水的氘盈余在-4.77‰～-12.48‰之间,d值严重偏负,说明水体的蒸发作用较强烈;(3)枯水期湖水的δ18 O、δD与COD、pH、EC、呈显著相关性,反映出蒸发分馏对COD等含量的影响;而水中TN、TP含量与δD和δ18 O比值无显著相关性,其含量的大小一定程度是受人为因素影响的。     

好氧颗粒污泥低温反硝化除磷的影响因素研究

以模拟城市生活污水为原水,在低温条件下研究SBAR反应器中好氧颗粒污泥反硝化除磷的效能。采用多组平行试验考察了pH、NO_3~-—N、NO_2~-—N、碳源类型对反硝化除磷的影响。结果表明:用乙酸钠作为碳源,pH控制在7±0.1,初始硝酸盐浓度为5 mg/L,或初始亚硝酸盐控制在15～30 mg/L时,有较理想的脱氮除磷效果。     

MBR-RO组合工艺生产直接饮用再生水的试验研究

采用膜生物反应器-反渗透(MBR-RO)组合工艺处理生活污水的过程中,MBR出水污染指数(SDI)在2.5~3.5之间,符合RO膜元件进水要求,且添加10mg/L阻垢剂后能有效控制RO膜的结垢问题。MBR-RO组合工艺的产水水质良好,其中常规水质指标COD_(Mn)浓度0.05mg/L、NH_4~+-N浓度0.15mg/L、NO_3~--N浓度2.82mg/L、NO_2~--N浓度0.7mg/L、TP浓度0.12mg/L,TOC浓度0.51mg/L,参照国家《生活饮用水卫生标准》中主要的73项指标分析,产水达到饮用水水质标准。本研究结果表明,采用MBR-RO组合工艺生产直接饮用再生水是可行的。     

南方低山丘陵区小流域不同土地利用方式下面源污染分布特征

南方低山丘陵地区经水土保持综合整治后,水土流失得到了有效遏制,但面源污染问题依然突出。研究小流域面源污染的空间分布规律,对面源污染的治理尤为重要。以松溪河小流域为南方低山丘陵区典型代表,结合实地调研,选择小流域内最具有代表性的3种土地利用类型各自汇水范围内的水塘及松溪河下游和小流域出口处作为采样点,利用2016年6-11月采集的3次水样,分析不同土地利用类型对总氮(TN)、铵态氮(NH_4~+—N)、硝态氮(NO_3~-—N)、总磷(TP)空间分布的影响。结果表明:总氮是小流域水体主要污染物,小流域出口处总氮浓度最高,为0.90～3.15 mg/L;居民点和农田对小流域面源污染贡献最高,这是因为南方低山丘陵小流域近年来经济发展较快,社会经济活动频繁但基础设施建设相对滞后;硝态氮浓度与总氮浓度的空间分布特征较一致,硝态氮、铵态氮与总氮在时间上的变化趋势相同;小流域氮素面源污染受到降雨的显著影响,磷素面源污染受到施肥习惯的影响。     

秦岭山区商洛市大气降水化学组成特征及来源分析

为了解秦岭山区城市大气降水化学组成与来源,2018年1-12月共收集商洛市有效降水样品40个,分析了p H、电导率(EC)和主要离子浓度(F~-、Cl~-、NO_3~-、SO_4~(2-)、NH_4~+、K~+、Na~+、Ca~(2+)和Mg~(2+))。结果表明:商洛市降水p H和电导率的加权平均值分别为6.76和34.35μS/cm,降水总离子浓度加权平均值为452.89μeq/L;主要阴离子为SO_4~(2-)和NO_3~-,分别占总阴离子浓度的59.20%和31.93%,主要阳离子为NH_4~+和Ca~(2+),分别占阳离子浓度的39.21%和33.87%,中和因子(NF)也表明二者中和能力最强;总离子浓度冬季高,夏秋季低,呈现明显的季节变化特征;相关分析表明NH_4~+、Ca~(2+)与SO_4~(2-)、NO_3~-之间相关系数均大于0.7,说明商洛大气中存在着NH_4NO_3、Ca(NO_3)_2、(NH_4)_2SO_4、CaSO_4和NH_4HSO_4等物质;富集因子计算表明,SO_4~(2-)和NO_3~-主要来自人为活动,Ca~(2+)、Mg~(2+)和K~+主要来自陆源的岩石土壤风化,Cl~-主要来自于海洋源。     

黄土塬区浅层地下水化学特征及其碳循环意义

对甘肃省灵台县独店镇秋射村黄土剖面浅层地下水的水化学组成、溶解无机碳(DIC)、溶解有机碳(DOC)、颗粒有机碳(POC)等进行了取样分析,对其δ~(13)CDIC和δ~(13)CPOC的特征及其控制因素进行了探讨,并评估了降雨补给过程中的碳酸盐风化碳汇强度。结果表明,研究区地下水的水化学类型为HCO3-Ca·Mg型,其方解石饱和指数SIC大于0,已经饱和,但尚未达到大规模沉淀的程度。研究区黄土浅层地下水的DIC变化范围为5.25~5.45mmol/L,DOC含量为0.59~0.62mg/L,明显低于地表水体;而POC稍高,这是因为黄土颗粒物的混入造成。泉水和井水的δ~(13)CDIC变化范围在-9.19‰~-8.90‰之间,其较高的δ~(13)C与碳酸盐风化-沉积过程中反复的碳同位素交换有关。而δ~(13)CPOC变化范围在-19.99‰~-18.87‰之间,与黄土有机碳同位素特征基本一致。地下水中的HCO-3、Ca2+和Mg2+主要来源于碳酸盐的化学风化。根据风化反应的离子平衡关系,计算得到研究区的风化碳汇为2.82mmol/L,即每有1L的降水入渗到零通量面以下,就会产生2.82mmol的碳汇。     

基于水化学和环境同位素的准格尔煤田地下水循环特征

为揭示准格尔煤田地区地下水循环特征,运用水化学技术、水汽轨迹模型和环境同位素等方法分析不同水体水化学特征、环境同位素特征、大气降水主要来源、地表水及地下水转化关系。结果表明:地表水矿化度低,呈弱碱-偏碱性,水化学类型以HCO_3·SO_4·Cl-Ca型水为主;地下水整体矿化度低,偏弱碱性,主要以HCO_3-Na·Ca型、Cl-Na型、HCO_3-Ca·Mg型、HCO_3·Cl-Na型水为主;黄河水δ(D)平均值为-79.6‰、δ(~(18)O)平均值为-10.47‰,第四系地下水δ(D)平均值为-66.25‰、δ(~(18)O)平均值为-9.1‰,白垩系地下水δ(D)值为-70.6‰、δ(~(18)O)值为-9.3‰,石炭-二叠系地下水δ(D)平均值为-77.07‰、δ(~(18)O)平均值为-9.9‰,寒武-奥陶系地下水δ(D)平均值为-75.73‰、δ(~(18)O)平均值为-10.06‰;大气降水受极地气团和季风影响,主要来源为西风带水汽、地表水和地下水水汽蒸发再循环;断层带、褶皱轴部裂隙带为不同含水层间主要导水通道,大气降水和黄河为地下水主要补给来源;高承压水头寒武-奥陶系岩溶裂隙水越流补给第四系松散孔隙水和砂岩裂隙水,第四系松散孔隙水通过地层间不整合接触面裂隙发育带向下补给石炭-二叠系砂岩裂隙水,黄河水对寒武-奥陶系地下水的补给比例受地质构造发育的影响较大。     

改性凹凸棒土/纳米铁复合材料去除地下水NO_3~--N的研究

采用液相还原法制备改性凹凸棒土/纳米铁复合材料(简称复合材料),考察了该复合材料的稳定性及其作用下"三氮"(NO_3~--N、NH_4~+-N、NO_2~--N)的变化情况,阐明了地下水环境因素(DO、温度、光照)对复合材料去除NO_3~--N的影响。模拟地下水环境时,3种材料去除NO_3~--N的反应活性顺序为:复合材料纳米铁改性凹凸棒土,且复合材料作用下NH_4~+-N的转化率低,几乎无NO_2~--N生成。DO、温度对复合材料去除地下水NO_3~--N的影响较大;而光照和黑暗环境下,地下水中NO_3~--N的去除率及NH_4~+-N、NO_2~--N的生成量均无明显差异。研究成果旨在为NO_3~--N污染地下水工程修复提供理论依据和技术支撑。     

Call for Papers

正As the eldest and most distributed professional journal of water industry,Water Wastewater Engineering(W WE)gained very wide acceptance from the colleagues working in this field in this country since start publication in 1964.Now it is administrated by the Ministry of Construction of the People’s Republic of China and sponsored by the China Civil Engineering Society etc.     

库水波动下库岸边坡地下水浸润线解析解及误差分析

解析法是库岸边坡地下水浸润线计算中便于实际应用的方法,但该方法须基于若干假定并对潜水运动基本方程线性化后才能求解。针对各假定和线性化过程建立不同的地下水渗流数学模型,用解析法和有限元法解答上述数学模型,分析各误差大小及其规律。结果表明：库岸垂直处理带来的误差要小于方程线性化处理和不考虑非饱和渗流带来的误差,而且它们都随渗透系数变大而减小;在三峡库区库水调度情况下,假定库水位等速变化带来的误差对大多岸坡而言可以忽略;计算库岸边坡地下水浸润线时,解析法只适用于水位变化幅度相比含水层厚度较小,且几何边界规则、岩土结构简单、岩土体渗透性较好时的情况。     

Changes in Summer Irrigated Crop Area and Water Use in Southeastern Turkey from 1993 to 2002: Implications for Current and Future Water Resources

Changes in summer irrigated cropland acreage and related water use are estimated from satellite remote sensing and ancillary data in semi-arid Southeastern Turkey where traditionally dry agricultural lands are being rapidly transformed into irrigated fields with the help of water from the Euphrates-Tigris Rivers. An image classification methodology based on thresholding of Landsat NDVI images from the peak summer period reveals that the total area of summer irrigated crops has increased three-fold (from 35,000 ha to over 100,000) in the Harran Plain between 1993 and 2002. Coupled analysis of annual irrigated crop area from remote sensing and potential evapotranspiration based estimates of irrigation water requirements for cotton indicate a corresponding increase in agricultural water use from about 370 million cubic meters to over one billion cubic meters, a volume in accordance with the state estimates. These estimates have important implications for understanding the rapid changes in current agricultural withdrawals in Southeastern Turkey and form a quantitative basis for exploring the changes in future water demands in the region. For example, expansion of irrigated lands have led to a steady decrease in potential evaporation due to increased roughness and decreased humidity deficit in the Harran Plain. Assuming that the changes in future evaporation conditions will be of similar nature, water use for irrigation is expected to decrease over 40 percent in future irrigation sites. Incorporating this decrease in overall planning of the irrigation projects currently under construction should lead to improved management, and by extension, sustainability of water resources in the region.     

浅谈优化Vray渲染在制作三维场景的应用研究

用Vray三维渲染引擎来渲染三维场景,其质量和速度是由一些影响因素和参数设置决定的,不同的参数和因素,可以得出不同的三维渲染效果.因此,分析、优化三维渲染质量和速度的影响因素,正确、合理的选择参数对提高Vray最后渲染阶段的质量和速度非常重要.     

固结、渗流和沉积控制方程研究

本文从两相流体动力学的守恒方程出发，考虑固相、液相的相对运动，推导了可以考虑场的不均匀性和流体压缩性的统一形式的控制方程，并对方程所基于的物理概念和相互联系进行了必要的分析。通过对方程适当形式的表达，可导出用于大、小变形固结、渗流和沉积的简化方程，显示了在不同领域的三个理论存在一定的统一性。方程推导过程并未对本构关系加以限制，适用范围较广。依据实际问题的要求，作了不同形式的简化。     

四川省及重庆市中型水电站效益分析

该文分析了四川省及重庆市几座中型水电站的调查材料表明：四川省及重庆市中型水电站不仅在川渝主网和地方电网中起着很大的作用，并具有巨大的社会效益，同时还有综合利用效益，说明修建中型水电站的优越性．     

Site modelling methods for detecting hydrologic alteration of flood frequency and flood duration in the floodplain below the carlyle dam,lower Kaskaskia River,Illinois, USA

Reports concerning the influence of dams on river hydrology vary among researchers, interest groups and government agencies. These often contradicting statements may occur because changes in hydrology caused by dams are distinct for each dam and river watershed. The objective of this research was to use site specific techniques to determine if the 1967 installation of the Carlyle Dam, lower Kaskaskia River, Illinois, altered flood frequency and duration within the forested floodplain located below the dam. Results indicated a decrease in flood duration and frequency, and a decrease in annual flood frequency variation at a site 6.4 km below the dam. Pre‐dam versus post‐dam differences in flood frequency and duration at the site 32.2 km below the dam were related to climate rather than dam effects. Although dam impacts are a concern, this research shows that distance downstream from the dam and downstream tributary and watershed characteristics should be considered before assuming that the dam has changed hydrologic parameters for portions of rivers. This research also indicates that areas of the lower Kaskaskia River may still maintain hydrologic ecological integrity, and could be targeted for restoration and adaptive management purposes. Hydrologic modelling combined with river gage and on‐site well measurement techniques presented in this study could provide detailed flood frequency and duration information for land use, sociological and geomorphological questions in focus areas within river floodplains. Copyright © 2008 John Wiley & Sons, Ltd.     

Statistical tools for thermal regime characterization at segment river scale: Case study of the Ste‐Marguerite River

Suitable thermal fish habitats are constrained by both maximum and minimum temperature tolerances. A multivariate and geostatistical approach was developed to estimate stream thermal characteristics at the river segment scale. Data from 22 temperature‐monitoring stations during summer 2007 were used to estimate monthly maximum temperature as well as thermal characteristics such as the number of events, the cumulative degree–days and the associated duration over specific temperature thresholds of 19 and 21°C. The probability of exceeding these temperature thresholds has also been interpolated. The methodology relies on the construction of a multivariate space using physiographic and hydrological characteristics of gauging stations as inputs in a canonical correlation analysis (CCA). A geostatistical interpolation technique, ordinary kriging, was subsequently used to perform interpolation in the physiographical space constructed using CCA. Results from this study were obtained for thermal characteristics estimated into two different interpolation spaces: (1) a 7 metrics space, and (2) an 8 metrics space. Cross‐validation technique has been performed and satisfactory results were obtained. Kriging thermal characteristics (magnitude and duration) into the 7 metric space for a 19°C threshold exceedance leads to best results with Relative Root Mean Square Error (RRMSE) ranging between 9.66 and 15.08%. The study shows that kriging in a multivariate space is a promising tool for water resources managers, especially in cases where risk mapping for lethal or sub‐lethal temperature thresholds may be required for a specific fish species. Copyright © 2010 John Wiley & Sons, Ltd.     

掺MgO混凝土的宏细观试验研究

利用MgO膨胀剂的延迟微膨胀效应能显著提高大体积混凝土的力学性能,产生的预压应力还能有效提高大体积混凝土抵抗温度开裂的能力,但目前对其微观机理研究不多。采用宏观与微观相结合的方式,研究了不同活性指数、不同掺量的MgO混凝土的力学性能,利用SEM/EDS微观分析手段揭示了MgO对混凝土性能影响的作用机理。试验结果表明：MgO取代部分水泥掺入混凝土中,混凝土的力学性能降低;掺量为4%~5%时,活性指数为100s的MgO混凝土的膨胀率大于活性指数为50 s的MgO混凝土;MgO混凝土的膨胀特性与Ca,Si,Mg,Al等元素的分布情况有关,掺入的MgO将改变界面区Ca,Si,Mg元素的富集特性,Ca元素和Mg元素更易于在界面区富集,导致混凝土宏观力学性能的降低。     

基于MIDAS软件探讨施工工序对深基坑稳定性的影响

基于武汉地铁名都站深基坑工程与水文地质勘察资料,建立了三维工程地质仿真计算模型。依据名都站深基坑开挖支护方案,利用有限元软件MIDAS的摩尔-库仑本构模型,对武汉地铁名都站深基坑施工过程中,不同施工工序下每步开挖之后,基坑的变形情况做仿真模拟计算,并对比分析其对基坑稳定性的影响。结果表明：基坑围护结构的变形情况与施工工序有很大的关系,施工工序越合理,上部土体变形越小,反之越大。因此,在基坑工程的施工过程中,要注重施工步骤的划分与合理安排,从而保证基坑工程的安全。研究成果为以后武汉地区基坑工程的施工设计提供了值得借鉴的经验。