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苏州城市河道底泥对磷酸盐的吸附与释放特征 总被引：4，自引：0，他引：4
为了探讨苏州古城区河道底泥对磷酸盐的吸附-释放特征,文中分别从改变上覆水的pH值、底泥吸附-释放动力学和等温吸附实验三个方面进行了研究。结果表明:(1)随着上覆水pH值的增大,苏州河道底泥对磷的吸附量逐渐减小;(2)底泥对磷的吸附过程是一个复合动力学过程,通常包括快吸附和慢吸附两个过程。底泥对磷的快速吸附在2h内快速进行,之后为慢吸附过程,到6h左右,基本达到一种动态吸附平衡;底泥对磷释放的动力学过程也包括快释放和慢释放过程。底泥释放磷在1·5h内快速进行,之后进入慢释放过程,磷酸盐含量基本稳定,达到释放平衡;(3)底泥具有较大的吸附磷的能力。随着上覆水的磷酸盐浓度增高,底泥吸附磷酸盐的量也增加。上覆水与底泥的比值越大,底泥对磷的吸附率越小。 相似文献
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为揭示波浪扰动对湖泊底泥磷释放的影响,在波浪水槽中模拟了不同波高情况下扰动对水体、水土界面、底泥间隙水的磷、溶解氧等的影响.结果显示,在大波扰动下,沉积物大量悬浮,水体总磷随之增加,溶解性磷增加却不显著;波浪扰动显著增加了水体和沉积物界面的溶解氧浓度,并增加了溶解氧在沉积物的侵蚀深度;波浪扰动降低了沉积物表层10 cm内间隙水中的磷浓度,而10 cm以下沉积物中间隙水中磷浓度基本保持不变.研究表明,波浪扰动可迅速增加水体中颗粒态的营养盐,但是对于溶解态营养盐,尤其是水体中活性磷浓度的影响,则受沉积物性质、水-沉积物间隙水磷浓度差,以及水-沉积物中氧含量等多方面因素的影响. 相似文献
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《吉林大学学报(地球科学版)》2015,(Z1)
<正>通过控制外源营养盐流入可以降低水体营养盐浓度,抑制蓝藻爆发。目前一些外源控制措施已经用于富营养化水体的修复,并取得一定成效。但是仅仅控制外源污染并不能抑制蓝藻爆发,底泥中营养物质的释放(内源污染)受到人们广泛关注。目前关于富营养化水体内源污染治理机制是抑制底泥中营养物质向上覆水迁移,如:底泥覆盖和底泥疏浚、生态修复等。但是这些措施成本高、时间长,难以大规模应用。本文基于磷是富营养化水体控制因子,研究铜绿微囊藻增值与底泥磷释放关系及其对底泥形态结构的改 相似文献
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北京官厅水库沉积物-水界面磷的分布和迁移特征 总被引：2，自引：0，他引：2
研究官厅水库一个沉积物柱及上覆水体磷的含量和形态特征,指出水体中的磷以颗粒态为主,界面上覆水中磷以无机磷酸盐为主,孔隙水中以有机磷占优势;界面附近湖水中总溶解磷、总无机磷、正磷酸盐和有机磷酸盐从远离界面到界面逐渐升高,孔隙水中总溶解磷、总无机磷、正磷酸盐在界面下10 cm左右达到最大值,有机磷含量由界面向下有增加趋势;计算了沉积物-水界面磷的沉降和扩散通量,分别为1967.5μg/a@cm2和0.5μg/a@cm2,结合沉积物中矿物组成、磷与Fe、Mn、SO2-4的关系,探讨影响磷分布和迁移的影响因素. 相似文献
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长江口及其邻近海域孔隙水地球化学特征 总被引：1，自引：0，他引：1
对长江口沉积物有机碳、总氮、总磷、Fe、Mn、AI及孔隙水和上覆水体中营养盐、Fe、Mn的含量进行了测试,结合早期成岩模型及地球化学热力学分析,探讨了在河口环境中影响孔隙水营养盐和Fe、Mn分布的主要因素,并对沉积物-水界面营养盐扩散通量进行了估算。结果表明,孔隙水中NH4^＋、NO3^-、PO3^4、H4SiO4和Fe、Mn的含量显著高于上覆水体。早期成岩过程是控制长江口沉积物孔隙水营养盐和Fe、Mn分布的主要因素。NH^4＋剖面暗示长江口近岸和远岸海域存在两类不同的生物地球化学过程。孔隙水Fe、Mn剖面暗示在河口环境中其是有机质降解的重要电子受体。在近岸海域MnO2可能是底部NH4^＋ -N移除的重要机制。长江口孔隙水中低磷酸盐与铁及沉积物中磷的形态有关。通量计算结果显示NH4^＋、NO3^-、PO4^3-、地SiO4、Fe和Mn向上覆水体扩散的通量分别为356—3074μmol／（m2·d）、-45．3～62．6μmol／（m2·d）、-0．3～1．7μmol／（m^2·d）、323—3172μmol／（m^2·d）、3．0～10．5μmol／（m^2·d）和35．7～439．5μmol／（m^2·d）。N、P、Si界面通量对上覆水体浮游生物所需营养盐的贡献分别为0．19％～1．65％、0．13％～0．14％和1．2％～12．2％,因此在考虑长江口区域浮游生物所需营养的来源时,沉积物-水界面营养盐扩散通量可以忽略。 相似文献
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以苏州市古城区劣Ⅴ类水体为研究对象,利用模拟试验方法,研究和探讨了水体环境条件(DO、Eh、pH值、温度)变化和疏浚深度对河道底泥氮释放的影响.底泥供试样中NH4+-N与NO3--N含量一般为0.277 g/kg与0.0012g/kg,上覆水体NH4+-N与NO3--N含量一般为6.743 mg/L与1.500 mg/L.试验结果表明:厌氧环境(DO<0.5 mg/L)、强还原环境(Eh<-108 mV)、酸性环境(pH<6.0)及温度升高均有利于底泥中NH4+-N的释放,NO3--N的迁移转化规律则相反;供试样控制疏浚深度5 cm、10 cm、15 cm、20 cm,当疏浚深度15 cm时,泥-水界面向上覆水体中扩散的氮通量最小;疏浚深度、DO和Eh对底泥NH4+-N释放程度的影响大于pH和温度,通过曝气等方式保持水体中适当的溶解氧或使底泥保持较强的氧化电位环境可以有效抑制底泥中NH4+-N的释放. 相似文献
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颗粒运移对蒋家沟土体渗透性影响的试验研究 总被引：4，自引：0，他引：4
对蒋家沟流域泥石流源区两种分散性不同的土(G1土具有强分散性,G2土无分散性)进行室内土柱自滤试验,研究了土柱在常水头(水头为5 cm)渗流过程中颗粒运移对土柱不同部位渗透性的影响。入渗液采用了煮沸过的清水与浓度为1 g/L的悬浮液(悬浮颗粒的粒径范围为1.6～104.74μm)。在清水渗流过程中,两种土样的入口处土层渗透性随着时间而增大,出口处土层的渗透性先增大后减少。在悬浮液渗流过程中,两种土的各土层的渗透性都有下降趋势,但在入口处土层最为显著,G1土样下降了一个数量级以上,G2下降了近两个数量级,且G2土所用时间较G1土短,即G2土的渗透性减少速率更加明显;两土柱中渗透流量都有显著减少。研究表明:土体的分散性在颗粒运移过程逐渐占主导地位,即强分散性土自身颗粒的运移明显,能抵消一部分外来颗粒的积聚堵塞作用。从试验结束后土柱的外观图像观察也发现,入渗的悬浮颗粒在土柱的各个位置都有分布,但主要沉积在入口处,这与土柱各层渗透性的变化相吻合。此外,两种土流失的颗粒都只是集中于渗流的开始阶段,流失颗粒粒径范围集中在数微米至数十微米之间。 相似文献
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天然矿物材料的多孔结构、结构组装和光催化性能 总被引：6，自引：0，他引：6
自然界存在丰富的多孔矿物资源,其孔隙结构使其具有良好的吸附性能,能够吸附聚集水体中的污染物(特别是有机污染物)。在分析天然多孔矿物的孔结构基础上,文中提出了结构组装的概念,即在多孔矿物中进行功能粒子组装,对多孔矿物进行表面修饰、微结构组装(如层状结构矿物的插层)。通过结构组装,在多孔矿物中引进功能粒子(如有光催化性能的TiO2 颗粒)。组装在天然矿物中的功能粒子能够降解聚集在其中的污染物,大幅度提高功能粒子的效果,提高光催化降解的功效,获得性能优异、成本低廉的天然矿物型有机污染物降解材料。此外,在同一矿物材料中复合小孔、中孔、大孔不同大小的孔结构,实现不同大小的孔径组装,也能够扩大光催化剂TiO2 的承载面积,提高吸附性能。经过结构组装的天然多孔矿物材料复合了吸附、光催化等性能,在环境治理特别是有机物污染降解方面有很好的应用价值。 相似文献
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Drinking water supply wells were constructed in the Sabarmati river bed aquifer of Ahmedabad city using radial pipes and
are known as French Collector wells. Contamination of groundwater from one of the French wells near Sabarmati railway bridge
was noticed in 1992. The suspected pollution sources are Duff-nala of Shahibaug and two other sources from slum dwellings
on either side of Sabarmati river. A combined groundwater flow, pathlines and a mass transport model was constructed covering
an area of 9 km2 to analyse the capture zone of the French well under two different scenarios. Aquifer parameters of the river bed aquifer
were available. Dry river bed condition was simulated under scenario I and controlled flow in the river bed was simulated
under scenario II. The groundwater velocity and migration of contaminant particles from sources was analysed in the pathline
model. Total dissolved solids (TDS) concentration contours originating from sources in the mass transport model (MT3D) were
computed by solving an advection-dispersion equation. The computed pathlines and TDS concentration contours indicate likely
migration of contaminant plume from pollutant sources to the French well during 365 days under two scenarios. The model results
confirm the tracer injection studies carried out to know the likely migration of contaminants towards the French well. The
modelling study emphasised the necessity of controlled release of surface water in Sabarmati river bed from Dharoi reservoir
throughout the year.
Received: 28 October 1998 · Accepted: 17 June 1999 相似文献
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M. Fathizadeh Ph.D. H. Fakhraee A. Aroujalian 《International Journal of Environmental Science and Technology》2011,8(4):863-871
In this paper, the photocatalytic decontamination of hexavalent chromium and tri-ethyl phosphate, two important wastewater contaminants, are studied by the ultraviolet / nano-titanium dioxide process. The pH value and synergic effect between the oxidation of tri-ethyl phosphate and the reduction of hexavalent chromium were investigated in different concentrations of tri-ethyl phosphate and hexavalent chromium. Furthermore, the effects of ultraviolet and nano-titanium dioxide were investigated in a solution which contained tri-ethyl phosphate and hexavalent chromium. Results of adsorptions showed that hexavalent chromium was adsorbed better in acidic pH while the better adsorption for tri-ethyl phosphate was occurred in alkalinity pH. The reduction rate of hexavalent chromium was higher in acidic solutions while it was obtained at natural pH for tri-ethyl phosphate. In co-adsorption of hexavalent chromium and triethyl phosphate pollutants, tri-ethyl phosphate slightly increased adsorption of hexavalent chromium, but hexavalent chromium had no influence on the adsorption of tri-ethyl phosphate on nano-titanium dioxide particles. In contrast, triethyl phosphate has an improving effect on the reduction reaction rate of hexavalent chromium which increases with the interaction of the concentration of tri-ethyl phosphate in mixture. The same is true for the oxidation rate of tri-ethyl phosphate. 相似文献
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Prediction of colloid release and transport as affected by reactive species remains a significant challenge for field applications. In this paper, we report experimental and modeling results of ferrihydrite colloid release under the influence of citrate species. Using a 3-plane surface complexation model, equilibrium constants were obtained for the three proposed inner-sphere complexes by fitting a citrate adsorption isotherm on ferrihydrite at pH 4, and a pH adsorption envelop with 0.64 mM citrate. The constants were used in a reactive transport model for simulating reaction fronts of dissolved species during injection of citrate in ferrihydrite-coated quartz columns. Simulation results show that sorption alone may not adequately describe the breakthrough curves. Inclusions of ferrihydrite dissolution and re-adsorption of Fe(III) improve the prediction of dissolved species transport. Additionally, matrix diffusion may be needed for improved prediction. For the release of colloidal iron oxides it was shown that both oxide dissolution and interfacial repulsion controlled the process during complete breakthrough. However, the peak release of colloids, which occurred during the actual breakthrough of dissolved species, was mainly brought about by electric double layer forces. These particles underwent detachment-deposition-detachment cycles along the flow path, and emerged in the effluent with the major reaction front. To quantitatively predict colloid release, a semi-empirical linear correlation was established, linking the calculated electric potential to experimental colloid release rates. The model may be applied to the prediction and scaling of aquifer remediation studies involved in the injection of organic ligands to mobilize particle bound contaminants. 相似文献
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Karst aquifers are very vulnerable to various pollution sources. Among these, landfills can contribute contaminants over long periods. Groundwater quality monitoring is required to assess the impact of a landfill leachate on underlying aquifer water or spring discharge. Tracer tests are useful for selecting the location and frequency of sampling. Three landfill sites in karst areas were studied with tracer tests. Additional insight was accomplished by the comparison of the tracer transfer and the breakthrough curves obtained from these tests with the results of two other tracer tests carried out in the same period in karst areas without a landfill. To explain the differences observed, the hypothesis of increased permeability below the landfill due to the presence of inorganic acids in leachates was further tested. The results of detailed, long-term monitoring of contaminated drip water in the Postojna Cave were used to verify the hypothesis. The analysis of the simultaneously increased content of calcium, magnesium, and contaminants in the drip water indicates a direct correlation between limestone dissolution and contaminants. Increased dissolution increases secondary porosity and thus permeability of the vadose zone resulting in higher vulnerability of underlying aquifers and springs in the vicinity landfills. 相似文献
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The mechanisms for storage of CO2 in rock formations include structural/stratigraphic, mineral, solubility and residual trapping. Residual trapping is very important in terms of both containment security and storage capacity. However, to date, the contribution from residual trapping (i.e. immobilisation of supercritical fluid via capillarity in pore spaces) is still relatively difficult to quantify accurately. Using a laboratory-based testing program, this study demonstrates the feasibility of using reactive ester tracers (i.e. triacetin, propylene glycol diacetate and tripropionin), which partition between a mobile water phase and a stationary supercritical CO2 phase, to quantify the residual CO2 saturation, Sgr, of a rock formation. The proposed single-well test involves injecting these tracers into the subsurface, followed by CO2 saturated water, where the ester tracers slowly hydrolyse to form products with differing partition coefficients. After a suitable period of time, allowing for partial hydrolysis, water containing the tracer mixture is produced from the subsurface and analysed using gas chromatography mass spectrometry (GCMS). A numerical simulator of the tracer behaviour in a reservoir is used to explain the differential breakthrough of these tracer compounds during water production to estimate Sgr. Computer modelling suggests that the use of esters tracers to determine CO2 residual saturation is a potentially robust method. The supercritical CO2/water partition coefficients directly dictate the amount of time that each tracer spends in the CO2 and water phases. As such for modelling of tracer behaviour and estimating Sgr, knowing the tracer partition coefficient is essential; in this paper, the first laboratory study to determine the partition coefficients of these reactive ester tracers is described. 相似文献
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为研究卢氏膨胀岩的胀缩特性,开展了干湿循环作用下膨胀岩的胀缩特性试验研究,并在膨胀岩经历干湿循环后利用扫描电子显微镜（SEM）和氮吸附试验（NA）,从微观的角度分析了膨胀岩吸水膨胀失水收缩的现象,并解释了胀缩特性改变的原因。研究结果表明：卢氏膨胀岩膨胀率随干湿循环次数增加而增大,绝对膨胀率增加25%;收缩曲线出现明显的“收缩拐点”,一般在收缩总时间的20%时出现,这时膨胀岩失水状态由自由水的散失转变为结合水的散失;在膨胀岩第1次胀缩过程中出现裂缝,裂缝为贯通状;在之后的胀缩过程中出现的裂缝较浅且随干湿循环次数的增加裂缝发育逐渐稳定;在干湿循环次数达到6～8次后,卢氏膨胀岩胀缩率达到稳定值,绝对膨胀率稳定在17%,绝对收缩率稳定在9%;微观方面随干湿循环次数的增加,膨胀岩的微观结构中黏土颗粒聚集形态由紧密状态转变为松散状态。此外,试样的孔隙特征随干湿循环次数的增加表现出孔隙总体积逐渐增大、孔径逐渐减小、比表面积逐渐增大的规律。 相似文献
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冻土未冻水含量的低场核磁共振试验研究 总被引：1，自引：0，他引：1
采用低场核磁共振技术测试了冻融循环过程中不同土质、不同NaCl离子浓度饱和试样的未冻水含量,结合T2分布曲线从微细观角度分析了冻融过程中未冻水在孔隙赋存分布情况。试验结果表明：冻结过程可分为过冷度段、快速下降段、稳定段3个阶段,而融化过程仅存在稳定段、快速融化段,并不存在与过冷现象对应的过热现象。冻结时大孔隙的水首先冻结,而融化时孔隙水的增加却是从小孔隙开始的,这是由水分热动力学势能的差异导致孔隙水冻结和融化在时间上的有序性。并且分析了冻融循环中土质类型、离子浓度对未冻水含量的影响,以及探讨了冻融过程出现的滞后现象的原因。 相似文献
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分析了有机污染物在土壤中的迁移转化机理，建立了非平衡吸附作用下渗滤液中有机污染物在土壤中迁移转化的动力学模型，给出了模型的数值解法，模拟出渗滤液在非平衡吸附作用下的污染过程；同时还探讨了模型参数降雨量p，垃圾土土层的厚度h，含水率θ等对有机污染物运移的影响。结果表明：在总的污染源一定的情况下，降雨量的增大和污染土层厚度的增大会使得下层土壤中有机物的浓度降低，为定量研究有机污染物在土壤-水环境系统中分配与归宿提供理论依据，同时也可为监测、治理和恢复地下水污染提供一定的科学根据。 相似文献