共查询到18条相似文献，搜索用时 171 毫秒
1.
重非水相液体(Dense Non-Aqueous Phase Liquid,DNAPL)与水相的界面面积是影响DNAPL在地下水中溶解速率的关键参数。通过设计二维砂箱实验,运用界面分配示踪法测定DNAPL残余饱和态下的界面面积。为量化分析保守示踪剂Br~-的存在对实验结果的影响,共进行两组实验,Br~-和界面分配示踪剂的注入方式分别为依次注入和同时注入。结果表明:(1)两组实验测定的固液相分配系数K_d值分别为0.079 m L/g和0.142 m L/g,表明Br~-的存在增大了介质对界面分配示踪剂的吸附作用;(2)两组实验测定的单位体积多孔介质中界面面积值分别为215 cm~2和237 cm~2,表明Br~-的存在增大了DNAPL与水相交界面对界面分配示踪剂的吸附作用;(3)在本实验范围内(Br~-浓度C_(Br)≤200mg/L),K_d值与Br~-浓度呈良好的线性关系(K_d=0.00032C_(Br)+0.0798),可用于对砂介质的K_d值进行估算和验证。 相似文献
2.
目前,刻画场地重非水相液体（dense non-aqueous phase liquid, DNAPL）污染常用的钻孔取样和井间分溶示踪试验方法成本高昂。相比而言,单井注抽试验节省经费,且对污染源区的扰动少,但该试验方法推估DNAPL残留量的准确性尚未得到定量验证。针对该问题,基于数值方法分析了示踪剂类型、注抽速率、污染源区结构等因素对单井注抽试验推估DNAPL残留量精度的影响。结果表明：（1）选用分溶系数比2,2-二甲基-3-戊醇（2,2-dimethyl-3-pentanol, DMP）低的己醇进行示踪,示踪剂回收更加充分,推估污染物残留量的平均精度增幅可达35.11%;(2)当注入速率从100 m3/d提高至130 m3/d、抽出速率从120 m3/d提高至150 m3/d,示踪剂接触的污染源区面积更大,均质源区对应的污染物残留量平均精度从42.45%提高到60.26%,非均质源区对应的平均精度从27.69%提高至48.72%;(3)污染源区结构复杂程度的增加会阻碍示踪剂的运移,非均质源区对应的平均精度比均质源区降低了13.15%;(4)单井注抽示踪试验更适用于离散状为主的污染源... 相似文献
3.
重非水相液体(dense nonaqueous phase liquid,DNAPL)污染土壤和地下水的问题已引起广泛关注,研究其在不同粒径多孔介质及其界面的运移特征形态是确定污染区域、修复治理土壤和地下水环境的前提。文章通过室内试验研究多孔介质界面对DNAPL运移与分布特性的影响。首先在二维砂槽上进行DNAPL污染物的入渗试验,试验过程中用数码相机拍照,将DNAPL扩散过程以图像的形式记录下来;然后用AutoCAD对图片进行处理,绘制出DNAPL迁移过程的锋面变化图。结果表明:DNAPL入渗过程中,迁移主要受到重力作用与毛细作用的控制,毛细作用力随着介质粒径的增大逐层减小,重力作用逐渐起主导作用使污染物入渗速度逐层增大;介质结构影响DNAPL的迁移形态,介质粒径逐层增大,DNAPL污染物的渗流面与指进扩散宽度逐层减小,扩散方式由面状变为指状;在不同粒径介质界面介质结构发生突变时,DNAPL迁移锋面线曲率也相应变大,此时DNAPL的迁移呈现“凸”型特征,另外,不同的界面横向扩散的滞留宽度不同,随着介质粒径的增大,界面的横向扩散宽度相对变短。 相似文献
4.
重非水相污染物(DNAPL)在地下介质中运移和分布受多种因素控制,包括DNAPL本身的物理化学性质,土的性质,泄漏条件等等。由于介质的非均质性,使得多相流运移行为更为复杂。基于地下水随机理论构建渗透率随机场,采用蒙特卡罗方法探讨泄漏速率对非均质饱和介质中DNAPL运移的影响。数值结果表明,在泄漏总量一定的情况下,泄漏速率越低,介质非均质性对DNAPL运移的影响程度越高。反之,DNAPL的渗漏速率越高,小尺度地层的非均质性影响越低。由于DNAPL运移过程中在垂直方向受重力的影响,污染羽在空间上的质心位置(一阶矩)以及展布范围(二阶矩)在垂直方向上的变异程度要高于水平方向。 相似文献
5.
对于重非水相污染场地,传统的钻孔取样方式因经费和取样个数的限制,往往无法准确估计含水层中重非水相污染物的残留量。井间分溶示踪法费用较低,且不会对污染源区造成破坏,可适用于推估重非水相污染物残留量,但目前该方法的准确性尚未得到验证。本文基于数值模拟方法探讨了示踪剂注入速率、示踪剂类型以及污染源区结构等多因素对井间分溶示踪估计重非水相污染物残留量准确性的影响。数值算例结果表明:井间分溶示踪实验估计重非水相污染物残留量的误差小于15%;降低示踪剂的注入速率使得分溶性示踪剂在非水相和水相流体间作用更充分,能够提高井间分溶示踪估计重非水相污染物残留量的精度,实验中示踪剂注入速率由500 m3/d降为250 m3/d后,多种情景的平均精度由91.68%提高至93%;选取低分溶系数的示踪剂有利于提高示踪剂的回收率,从而提高推估精度,实验中示踪剂由2,2-二甲基-3-戊醇改为己醇后,平均精度由87.83%提高至96.85%;复杂的重非水相液体污染源区结构易于出现示踪剂绕流等现象,导致井间分溶示踪估计重非水相污染物残留量的误差增大,实验中含水层由均质变为非均质后,平均精度由93.03%变为91.65%。重非水相污染场地调查时,建议结合数值模拟方法选择适宜的示踪剂和示踪剂注入速率,以提高污染场地的刻画精度。 相似文献
6.
实验研究了W、Sn、Be、Nb、Ta在不同压力(150 MPa、100MPa和50 MPa)、温度(850℃和800℃)条件下,于水饱和含P过铝质岩浆体系(P2O5分别为0.32%、1.98%、4.91%和7.78%)中流体-熔体间的分配.研究结果显示,W、Sn、Be、Nb、Ta在流体/熔体相间的分配系数Di＜0.1,表明它们强烈分配进入熔体相.W、Nb、Ta在流体/熔体相间的分配显示压力相关性随压力降低而降低. 相似文献
7.
将描述示踪剂为非保守、瞬时投源条件下的一维河流水团示踪试验的解析表达式进行2次适当的变形,分别得到一个二元和一元线性方程。对二元线性方程应用相关系数极值法,可以推导出计算河流横断面平均流速的公式;利用直线图解法或一元线性回归法能够计算出一元线性方程中的2个常数值,据此可以计算河流的纵向离散系数DL与示踪剂的一级反应速率常数k。与现有的数据分析方法相比较,该方法具有:(1)适用于示踪剂为非保守的情况;(2)利用一组野外试验数据可以同时计算河流离散系数DL、河流横断面平均流速V与示踪剂的一级反应速率k常数3个参数值;(3)全部数据分析过程可以程序化,由计算机完成等特点。 相似文献
8.
锡的成矿与花岗岩有着密切关系。为深入了解不同的岩浆组成及流体变化对锡分配行为的影响,以不同化学组成的凝胶和不同的流体分别作为初始固液相,进行了锡在流体与花岗质熔体间的分配行为实验研究。实验温度为850℃,压力为100 MPa。结果显示,当液相为0.1 mol/L的HCl时,熔体组成的变化对锡的分配行为有着明显的影响,锡在流熔体间的分配系数DSn随熔体中碱质(Na2O K2O)含量、钠钾(Na/K)和碱铝(AlK/Al)摩尔比的增加而减小;在固相(富钾过碱质熔体)不变的前提下,DSn随流体相中HCl浓度的增加而增大,而流体相中HF及K 、Na 浓度的改变对DSn影响不大;流体Cl-浓度和酸度升高有利于锡分配进入流体相。 相似文献
9.
韩智颖王锦国崔孜铭杨蕴 《地质灾害与环境保护》2022,(3):71-77
选定氯苯为典型DNAPL建立理想的地表污染泄漏多相流运移模型,利用TOUGH系列软件TMVOC模块进行数值模拟,探讨地下水动力、介质非均质性及两种因素协同作用时对DNAPLs运移和分布的影响。研究结果表明:(1)水力梯度增大了DNAPL水平和垂向运移速率;当水平向水力梯度过大时,反而导致垂向速率减小。(2)透镜体主要发挥阻滞作用,绕过透镜体后,下游侧污染指入渗深度明显大于上游侧;水力梯度的存在进一步增强介质非均质性的影响,产生更多集聚和绕流,形成不规则的污染指和污染池交替组合形态。 相似文献
10.
硅酸盐熔体和流体中金的性质及行为研究进展 总被引：1，自引：0，他引：1
岩浆演化过程中岩浆—流体阶段发生的相转变过程控制了元素在两相之间的分配行为。作为与岩浆热液活动有密切成因联系的金矿床,其在硅酸盐熔体和流体中的性状及两相间的分配行为是控制该类矿床成矿的重要物理化学因素。介绍了金在流体、熔体中的性状,论述了其在流体/硅酸盐熔体间的分配行为不仅受温度、压力、氧逸度等物理化学条件的影响,还受流体组分(阴离子、阳离子)、熔体组成(Na2O+K2O/Al2O3,Na/K,SiO2,NBO/T)的制约;最后对目前实验研究存在的问题、改进方法以及今后的研究方向进行了探讨。 相似文献
11.
Quantification of the saturation degree of nonaqueous phase liquid in the vadose zone using hydrocarbon partitioning tracers 总被引：1，自引：1，他引：0
Partitioning tracer tests, as an alternative to the core sampling method, were conducted to quantify the degree of saturation
of water and nonaqueous phase liquids (NAPL) in the vadose zone. Hydrocarbon gases, which have less effect on global warming
than conventional tracers, were used as partitioning tracers. Column tests using CH4, C3H5, and C4H10 as non-partitioning and partitioning tracers were performed to determine the retardation factor and partition coefficient
of the tracer into water and NAPL. The retardation factors of these tracers were estimated to be in the range of 1.0–7.0 based
on breakthrough curves of the tracers. The partition coefficient of C3H5 to water and diesel phase was calculated to be 0.57 and 8.45, respectively. For a heavier tracer, C4H10, the partition coefficient to the water and diesel phases was 1.2 and 40.5, respectively. The average value of water and
diesel saturation estimated from column tests agreed well with known values in unsaturated soil. A residence time longer than
7.5 h within soil pores was found to provide local equilibrium partitioning of the tracer to the diesel phase. The concentration
of tracer had no effect on the partitioning process. 相似文献
12.
Pollution source characterization by the Partitioning Interwell Tracer Test method requires the assessment of the partitioning coefficient of the tracers with the pollutant. Experiments conducted on batch tests (static) and laboratory columns (dynamic) indicated a partitioning kinetics between the reactive tracer (4-methyl 2-pentanol) and the organic phase (trichlorethene); the partitioning coefficient decreases when the flow velocity through the porous medium increases. This partitioning kinetics has been confirmed by the interpretation of the tracer breakthrough curves with a first-order kinetic transfer model. To cite this article: M. Bohy et al., C. R. Geoscience 336 (2004). 相似文献
13.
选用四氯乙烯（PCE）作为典型DNAPL污染物,以NaCl作为地下水中溶解盐代表,研究盐度对DNAPL在饱和多孔介质中运移和分布的影响。通过批次实验测定NaCl水溶液/石英砂/PCE三相体系下的接触角和界面张力,结果表明,PCE在石英砂表面的接触角随着水中NaCl浓度的增大而减小,而PCE和NaCl水溶液的界面张力随着NaCl浓度的增大而增大,尤其当氯化钠浓度较高时（>0.1 mol/L）,影响程度更为显著。在此基础上,采用透射光法监测不同介质情景下DNAPL在二维砂箱中的运移和分布,定量测定DNAPL在介质中的饱和度。实验结果表明,地下水盐度的增加将促进DNAPL的垂向入渗,减少被截留在运移路径上的DNAPL量,使得DNAPL运移路径及累积形成的池状DNAPL（pool）向水流方向偏移。在均质多孔介质和含有透镜体的非均质多孔介质中,随着盐度的增加,DNAPL在横向和垂向上的展布均呈现出增加趋势,导致污染源区变大,且介质中以离散状存在的DNAPL量明显增加。 相似文献
14.
Partitioning tracer method for quantifying the residual saturation of refined petroleum products in saturated soil 总被引：1，自引：1，他引：0
The effective site assessment is crucial to the successful remediation of the subsurface contaminated with light nonaqueous
phase liquids (LNAPLs). Recent studies showed that large spatial volumes of the subsurface contaminated with LNAPLs could
be investigated with the partitioning tracer method. This study investigated the applicability of the partitioning tracer
method for detecting and quantifying refined petroleum products in a saturated aquifer containing alluvial soil or weathered
granite soil. In the batch-partitioning experiments, the partition coefficients of alcohol tracers between the petroleum mixture
and water were measured, and they were found to be increased in proportion to the boiling points of the alcohol tracers when
the molecular weights of the alcohol tracers were similar. The sorption isotherm experiments indicated that a considerable
amount of 4-methyl-2-pentanol was sorbed into Jumunjin sand (JS) or weathered granite soil (WGS). In the column experiments,
it was confirmed that the partitioning tracer method could be used as a method for detecting the presence of the petroleum
mixture in saturated soil, and the residual saturation of the petroleum mixture in the soil column prepared by firstly contaminating
with the petroleum mixture and secondly saturating with water was measured higher than that in the soil column prepared by
firstly saturating and secondly contaminating. The highest accuracy of estimation using the partitioning tracer method was
found for 2-ethyl-1-butanol and the lowest accuracy was found for 4-methyl-2-pentanol. 相似文献
15.
Analytical closed-form solutions for assessing pumping cycles,times, and costs required for NAPL remediation 总被引：2，自引：0，他引：2
R. Chesnaux 《Environmental Geology》2008,55(7):1381-1388
An analytical solution is given to evaluate the number and duration of pumping cycles required for the remediation by pumping
of contaminants, both single component and multi-component non-aqueous phase liquids (NAPLs), when no free product is present
in the system. The method can be applied in a homogenous medium if the contamination zones have been delineated and residual
total NAPL concentrations assessed. Based on the principle of the NAPL partitioning in unsaturated or saturated porous media,
analytical closed-form solutions are provided for both cases of remediation by pumping in saturated and unsaturated conditions:
“pump-and-treat” and “soil vapor extraction”. In each case we determine the number of pumping cycles required to reach the
residual required concentration of NAPL (for example, according to health-based standards), considering one or more chemicals
simultaneously present in an aquifer. The method requires information on the aquifer saturation state and the properties of
the chemicals of interest. Calculations are based on the assumption of equilibrium partitioning of chemicals between the pore
water, the soil solids, and the soil gas (in the case of unsaturated conditions), and no presence of a NAPL phase. 相似文献
16.
在二维均质饱和孔隙介质中利用光透法与高密度电阻率法定量监测重非水相液体(DNAPL)的运移过程与饱和度。 将光透法与高密度电阻率法相结合,进行高密度电阻率法对 DNAPL 在饱和多孔介质中渗流过程的定量监测。在二维砂箱 中进行 DNAPL 的入渗试验,应用光透法与高密度电阻率法进行动态监测,分别利用 CCD 相机、LCR 数字电桥采集数据。 光透法的数据处理采用“水-DNAPL”两相中 DNAPL 饱和度的计算公式。而高密度电阻率法的数据处理是将获得的电阻值 数据转化为电阻率值,然后利用 Archie 公式获得重非水相液体的饱和度空间分布。Archie 公式中参数β值本文采用与光透法 相结合的新方法来获取,克服了传统方法获取β值时存在的困难。根据不同时刻的饱和度空间分布可以估算注入砂箱内的 DNAPL 总量,并将其与实测的入渗量进行对比。结果表明,与光透法结合后的高密度电阻率成像法能定量监测饱和孔隙介 质中 DNAPL 的入渗过程,且估算的 DNAPL 入渗量与实测值比较吻合,提出的基于光透法计算β值的新方法是有效且可行的。 相似文献
17.
Victor Ryzhik 《Computational Geosciences》2007,11(1):1-8
Spreading of a non-aqueous phase liquid (NAPL) denser than water (DNAPL) lens (mound) in the unsaturated zone of double-porosity
aquifer above an impervious plane boundary is investigated. The double-porosity aquifer is conceptualized as a fracture network
surrounding pervious blocks. Vertical gravity equilibrium is assumed to prevail in each one of the two media, fractures and
blocks. Through vertical integration, two coupled partial differential equations for the DNAPL content in each medium are
obtained. The mass exchange rate between high- and low-permeability media is considered as a function of NAPL content. The
dominant effect is gravity, whereas capillary forces are negligible. Analytical solutions for one-dimensional and axisymmetric
problems of mound spreading are obtained. 相似文献
18.
重非水相（DNAPLs）是地下水常见的有机污染物,理解其运移机制对于污染物修复具有重要意义。为解释实验中多孔介质润湿性对DNAPL的流动速度及残余饱和度的影响,使用多相流相场法,在构造的二维孔隙中模拟DNAPL液滴的下落过程。结果表明：模拟能准确刻画多相流界面的不稳定性,重现与实验室尺度相似的现象。文章提出的双界面模型相较于以往的微观模型能够更好的解释介质润湿性对DNAPL运移的影响。DNAPL的下落速度受前后界面共同影响,而饱和度主要由后界面决定。同时,润湿性对运移的影响大小受制于多孔介质的非均质性。 相似文献