洛阳市区包气带中污染物自净规律初步研究

包气带是地下水补给和地下水污染的主要通道,因此包气带的性质直接控制了地下水的污染化速度和程度。以洛阳市区洛河河床岩性（以砂砾石为主）以及由亚粘土、亚砂土、中细砂等介质构成的包气带为研究对象,来分析河床和包气带对污染物的自净能力,并对其天然的自净机制进行了简要的分析,结论如下：洛河河床岩性对各种污染物（NO3-除外）的净化能力均达到90％以上;亚粘土、亚砂土、中细砂等包气带介质层对重金属（Cu^2＋、Pb^2＋等）有很强的净化能力,而对Cl、Cr^6＋净化能力则较弱,在短时间内介质中就达到饱和而失去净化能力;在环境条件相近及水文地质条件基本相同的条件下,包气带厚度与地下水的污染程度呈负相关关系;污水经过包气带发生较强的过滤、吸附、离子交换、生物化学降解等作用,能有效地去除污水中的有害物质,防止地下水污染。     

包气带介质截留不同龄垃圾渗滤液中的有机污染物

从渗滤液场龄和包气带岩性两方面着手,研究了不同岩性包气带介质对不同场龄渗滤液中有机污染物的截留作用规律。结果表明:新渗滤液经过以细砂、亚粘土为介质的包气带后,细砂和亚粘土中有机物的质量分数分别从0.70%和0.87%增大至0.80%和1.00%以上,而老渗滤液使细砂和亚粘土中有机物的质量分数降至0.70%和0.50%以下。新渗滤液经过包气带后,包气带介质中有机物的含量增大,而老渗滤液使包气带介质中有机物的含量降低,亚粘土较细砂更容易受到渗滤液污染的影响。即渗滤液性质对包气带介质中有机物含量具有方向性的影响作用,而包气带介质亚粘土比细砂更容易放大这种作用效果。     

应用土柱试验求解地下含水介质弥散系数

污染物质在地下含水介质中的运移,除受渗透系数等水文地质条件的制约外,还受到含水介质弥散系数的控制。污染物的扩散,首先是从包气带开始进行的,浑河冲洪积扇地包气带主要岩性是亚粘土及亚砂土,因此,计算出浑河冲洪积扇包气带的弥散系数,对于认识污染物的运移能力是一项必要的工作。本文利用室内动态土柱装置,模拟包气带岩性环境,以0.05 mol/L的NaCl溶液作为示踪剂,经长时间监测,运用弥散系数计算公式进行求参。计算结果是包气带以亚粘土为主要岩性的弥散系数为0.005 71 m2/d,亚砂土的弥散系数为0.012 47 m2/d。     

泰安市第四系水文地质结构对浅层地下水污染敏感性控制作用研究

通过对泰安市第四系水文地质结构研究发现, 浅层地下水的污染受地层结构的控制, 在包气带岩性及含水层岩性相同的条件下, 包气带的厚度越大, 其防污性能越高, 含水层遭受污染的程度越小; 在地面环境质量及包气带岩性和厚度相近的条件下, 粗砂含水层较粉质粘土含水层更易遭受污染      

垃圾渗滤液有机污染组分在包气带中衰减规律的模拟研究

用若干土柱模拟试验研究了垃圾渗滤液有机污染组分在不同岩性、不同厚度包气带介质中的运移规律,并计算了有机污染组分在包气带中运移的有关水化学迁移参数(阻滞因子R和水化学迁移率E).结果表明,有机污染组分在不同岩性介质中的R值顺序为:粘土＞亚粘土＞砂土,在相同岩性中随着厚度的增加R呈正相关增大.从而为评价和预测垃圾场对地质环境影响提供技术参数,并为垃圾场的选址提供理论依据.     

垃圾渗滤液的特征污染组分在包气带中的迁移转化规律

通过室内土柱实验,研究了垃圾渗滤液的特征污染组分氮、COD在包气带不同介质中的迁移转化特征。实验结果表明,岩性不同的包气带介质是影响氮素、COD迁移转化的重要因素之一,不同介质对氮、COD的净化能力不同;渗滤液对地下水不会造成氮素污染,但会造成有机污染。     

包气带土层对氮素污染地下水的防护能力试验研究

包气带土层能够有效滞留和吸附污染物,是阻隔污染物进入地下水的重要屏障。通过对北京市典型地区包气带土体进行土柱淋溶试验,研究包气带土层对氮素污染地下水的防护能力,实验结果显示,包气带土层对氮素的截污性能具有明显的分段性。粘质粉土对氮素污染地下水具有较强的截留和防护能力,粉砂截留和防护能力相对较差。经计算粘质粉土和粉砂对再生水的净化能力分别为83.3%、29.1%。包气带土层颗粒粒径愈大,污染物浓度高,水动力条件好,包气带土层的防护能力愈差。     

陕北风沙滩地区包气带抗污能力试验研究

为了研究陕北风沙滩地区包气带风积沙的抗污能力,在榆林煤化工厂厂区及其周边地区选择4个试验点,采用双环入渗法,选择渣场炉渣浸出液（Cd、Cr、Cu、Mn、Ni和Pb重金属污染物溶液）进行渣场污水入渗试验,采用人工配置污染物溶液（COD、氨氮、F、石油类和挥发酚）进行了配污试点试验。渣场污水入渗试验过程中,由于水流的冲刷作用,剖面上大部分污染物的含量都小于入渗前的含量;而渗后样的测定结果则表明包气带风积沙对污水中Cr、Cu、Mn、Ni和Pb的净化能力较强。配污试点试验表明包气带对无机污染物的阻滞作用会延缓其对地下水的污染,石油类在包气带中的运移速度缓慢,难以在水流的作用下到达含水层,而COD容易造成地下水污染,挥发酚对含水层的污染能力要小于COD。应考虑采取适当方式降低地下水位,增大包气带厚度,以加强包气带对地下水的保护能力。     

河津市黄河沿岸水源地保护措施分析

河津市黄河沿岸水源地位于河津市境内汾河与黄河汇流处的三角地带,总面积 88 km2,该水源地有良好的贮水构造和充沛的补给来源,是山西铝厂、河津电厂及王家岭煤矿的主要供水水源.从水源地水环境状况来看,对水源地水体造成污染的主要污染源有:北部基岩山区遭受污染的水体对水源地的补给、涧河地表水对水源地的污染、工矿企业对地下水的污染、汾河对水源地的污染.根据水源地污染机理分析,水源地上覆的包气带较薄,岩性主要为细砂和薄层亚砂土,抗污性较差,水源地保护主要应采取防渗、治污及涵养水源的治理方式.保护工程主要包括涧河防渗渠道及水源地周边污水集中排放管道工程、废污水处理工程及绿色生态(水源涵养)工程.     

利用地中渗透仪观测资料进行降雨入渗补给规律分析

利用郑州地下水均衡场地中渗透仪实测资料，分析了降雨入渗补给的年际变化以及入渗补给过程中的滞后现象。通过计算降雨入渗系数，确定了降雨量与入渗量的定量关系，评价了不同降雨量、不同包气带岩性和厚度条件下的入渗补给量。研究表明，地下水埋深较小时，降雨入渗系数随着埋深的增加而增大，1m以下则逐渐减少，3m以下趋于稳定；当包气带岩性单一时，降雨入渗系数随岩性的不同而变化，即砂质土大、粘性土较小，而含有薄层粘土夹层的亚砂土最小。     

包气带岩性结构对地下水生态功能影响特征

西北内陆流域下游区天然植被对地下水生态功能具有强烈依赖性,而包气带岩性结构对地下水生态功能具有明显影响,但是在目前的研究中,缺乏定量分析评判。以甘肃石羊河流域下游天然绿洲区为研究区,基于包气带岩性结构野外调查、室内土柱试验和Hydrus1-D数值模拟,研究包气带岩性结构与地下水耦合作用的生态效应,分析不同岩性结构包气带...     

包气带粘性土层的防污性能试验研究及其对地下水脆弱性评价的影响

大量文献资料分析表明,平原地区地下水脆弱性主控因素为地下水位埋深、包气带土层及其特征,而包气带粘性土层的截污性能及其厚度则又是脆弱性主要的影响因子。试验研究结果显示,粘性土的截污容量大小可以通过模拟淋滤实验测试得出,有效阻隔足额厚度也可计算得出。根据不同粘性土层的截污容量、有效阻隔厚度等,可以评判土层的污染防护能力,并可据此评价平原区地下水的脆弱性。     

Distribution of groundwater salinity and formation mechanism of fresh groundwater in an arid desert transition zone

This study reviews the distribution of groundwater salinity in an arid desert transition zone. By combining field experiments and computer simulation models we make a comprehensive analysis of the formation mechanism of fresh groundwater in relation to the paleogeographic conditions of lithofacies, the geochemical characteristics of the aquifer media, salt deliverability in the vadose zone and prevailing hydrodynamic conditions. The results demonstrate that (1) the lacustrine facies deposition stratum of the Huanhe formation in the Cretaceous system provides a brackish-salt groundwater environment; (2) the average salinity of parent rocks are approximately 440 mg/kg and 4 371 mg/kg in the Quaternary eolian sand and the Cretaceous Huanhe formation respectively, suggesting that parent rocks are the principal controlling factor in the distribution of groundwater quality given that mineral and chemical composition of the eolian sand is simpler than that of the Huanhe formation; (3) average groundwater flow rates are approximately 0.25 m/d and 0.1 m/d in eolian sand and Huanhe formation aquifers respectively, indicating that hydrodynamic conditions play an important role in driving in the formation and evolution of fresh groundwater; (4) The salinity deliverability in the vadose zone overlying the aeolian sand and Huanhe formation aquifers are approximately 15.97 mg/L and 220.42 mg/L respectively, signifying that the combination of lithology and salt content of vadose zone, rainfall infiltration, evapotranspiration and concentration heavily influence the formation, distribution and evolution of groundwater quality. This study can provide a scientific basis for the sustainable development and utilization of groundwater resources in arid areas.     

Assessment of spatial relationship between groundwater pollution vulnerability and quality indices in Kano,Nigeria

Safeguarding groundwater from pollution is largely a global political decision. These decisions are basically supported by DRASTIC (D=Depth to water, R=Recharge, A=Aquifer media, S=Soil media, T=Topography, I=Impact of vadose zone, C=Hydraulic conductivity) analysis. Furthermore, water quality index (WQI) is an effective tool for groundwater quality evaluation and management. This study identifies the relationship between these two indices [i.e., pollution vulnerability index (PVI) and WQI]. The DRASTIC index of the study area was found to be from 60.4 to 178 characterized by very low, low, medium high, and very high vulnerability constituting of 12.88, 24.38, 34.11, 21.99, and 6.63% of the study area, respectively. In addition, the WQI of the area according to the analyzed parameters is between 10.19 and 55.63. It was established that a good correlation (61%) was found to exist between the two indices; which may be an indication that most pollutants present in the groundwater are likely due to anthropogenic activities on the land surface.     

地下水环境容量研究——以郑州市平原岗区为例

同地表水体一样,地下水系统本身也具有一定的纳污能力,即地下水环境容量。目前,国内外真正意义上的地下水环境容量研究开展得非常少,主要是进行了与地下水环境容量相关的地下水溶质迁移理论和试验研究。以郑州市平原岗区为例,分析了污染物在土壤包气带中随下渗水体向下迁移的机理过程,借助数值模型计算了不同岩性和厚度包气带的水环境容量,成果可为地下水污染防治提供科学依据。     

Assessing Groundwater Resource Vulnerability by Coupling GIS-Based DRASTIC and Solute Transport Model in Ajmer District,Rajasthan

Groundwater aquifer vulnerability has been assessed by incorporating the major geological and hydrogeological factors that affect and control the groundwater contamination using GIS-based DRASTIC model along with solute transport modeling. This work demonstrates the potential of GIS to derive a vulnerability map by overlying various spatially referenced digital data layers (i.e., depth to water, net recharge, aquifer media, soil media, topography, the impact of vadose zone and hydraulic conductivity) that portrays cumulative aquifer sensitivity ratings in Kishangarh, Rajasthan. It provides a relative indication of groundwater aquifer vulnerability to contamination. The soil moisture flow and solute transport regimes of the vadose zone associated with specific hydrogeological conditions play a crucial role in pollution risk assessment of the underlying groundwater resources. An effort has been made to map the vulnerability of shallow groundwater to surface pollutants of thestudy area, using soil moisture flow and contaminant transport modeling. The classical advection-dispersion equation coupled with Richard’s equation is numerically simulated at different point locations for assessing the intrinsic vulnerability of the valley. The role of soil type, slope, and the land-use cover is considered for estimating the transient flux at the top boundary from daily precipitation and evapotranspiration data of the study area. The time required by the solute peak to travel from the surface to the groundwater table at the bottom of the soil profile is considered as an indicator of avulnerability index. Results show a high vulnerability in the southern region, whereas low vulnerability is observed in the northeast and northern parts. The results have recognized four aquifer vulnerability zones based on DRASTIC vulnerability index (DVI), which ranged from 45 to 178. It has been deduced that approximately 18, 25, 34, and 23% of the area lies in negligible, low, medium and high vulnerability zones, respectively. The study may assist in decision making related to theplanning of industrial locations and the sustainable water resources development of the selected semi-arid area.     

石家庄市地下水污染及其污染质排放的最优化控制

文章指出不考虑地域、条件,一律采用《工业“三废”排放试行标准》的不合理性。提出了用负荷控制来代替目前采用的污染质排放的浓度控制、总量控制,并从石家庄市地下水污染现状出发,建立了以该市地下环境系统最大限度容纳污染质为目标的线性最优化模型;得出该市防止地下水污染的排放浓度;求得了污水允许渗入量区间和地下水开采模数区间。     

Prediction of 1,2,4-trichlorobenzene natural attenuation in groundwater at a landfill in Kaifeng,China

1,2,4-trichlorobenzene (1,2,4-TCB) is one of the most common pollutants in landfill leachate that impacts shallow drinking groundwater quality; accordingly, the transport mechanism and capacity for remediation of this compound are important to the management of local water resource. In this study, a series of indoor experiments and analytical predictions revealed that the transportation of 1,2,4-TCB in groundwater is similar in medium sand and fine sand. Specifically, the peak time increases with distance between monitoring points and the source point, but the peak relative concentrations decrease with distance, indicating that the concentration of 1,2,4-TCB in groundwater is controlled by adsorption and biodegradation. In addition, transportation of water in a fine sand column was lower than that in a medium sand column; therefore, the adsorption and biodegradation of 1,2,4-TCB in groundwater was lower in the medium sand column. These findings demonstrate that 1,2,4-TCB in groundwater could be removed by natural degradation after about 5 years, but that other methods (permeable reactive barriers, air sparging or biosparging) should be applied in the field to shorten the remediation period and enhance water supply safety around landfill.