共查询到20条相似文献，搜索用时 15 毫秒
1.
Integrated surface electrical resistivity and electromagnetic (EM) surveys were conducted in a hard-rock terrain of Southwestern
Nigeria in the vicinity of active oxidation sewage treatment ponds. The aim was to detect soil contamination due to the spread
of sewage effluent, locate possible leachate plumes and conductive lithologic layers, and access the risk of groundwater pollution
in the vicinity of the sewage-ponds. Dipole–dipole resistivity profiling and very low frequency (VLF) data were acquired at
10-m intervals along five 200-m long east-west geophysical traverses. Resistivity sections obtained revealed four subsurface
geologic layers comprised of lateritic clay, clayey sand/sand, weathered/fractured bedrock, and competent bedrock. A distinct
low resistivity zone corresponding to the contamination plume (labeled B) was delineated from all the resistivity sections.
This low zone extends into the weathered bedrock and possibly suggests contamination of this layer. The filtered real component
of the processed VLF data detected three distinct anomaly zones that are representative of fractured zones filled with conductive
fluids and/or lithologic boundaries that possibly serve as conduits for the movement of contaminated effluents. The results
obtained from the two methods suggest possible contamination of the subsurface soil layers and groundwater in the vicinity
of the sewage-ponds. The existence of this contaminated plume poses a serious threat to the ecosystem and health of the people
living in the vicinity of the sewage-ponds. 相似文献
2.
Wasiu Olanrewaju Raji Ifedolapo Gbadesere Obadare Marry Abiodun Odukoya Lukman Mobolaji Johnson 《Arabian Journal of Geosciences》2018,11(7):144
Three years after the oil spillage and pipeline explosion that claimed about 100 human lives at Ijegun Community of Lagos–Nigeria, a combination of carefully designed 2D Electrical Resistivity Profilling and Vertical Electrical Sounding methods was deployed to map and characterise the subsurface around the contaminated site. Data acquired were processed, forward modelled and tomographically inverted to obtain the multi-dimensional resistivity distribution of subsurface. The results of the study revealed high resistivity structures that indocate the presence of contaminant (oil plumes) of different sizes and shapes around the oil leakage site. These high resistivity structures are absent in the tomograms and resistivity-depth slices computed for Iyana—a linear settlement not affected by oil spillage. The five geo-electric layers and the resistivities delineated in the area are the top soil layer, 220–670 Ωm; clayey sand layer, 300–1072 Ωm; top sand layer, 120–328 Ωm; mudstone/shale layer, 25–116 Ωm and the bottom sand layer, 15–69 Ωm. The base of the first four geo-electric layers corresponds to 3.9, 8.4, 27.2 and 34.6 m respectively. The two groundwater aquifers delineated correspond to the third and fifth geo-electric layers. The top aquifer has been infiltrated by oil plumes. The depth penetrated by the oil plume decreases from 32 m to about 24 m across the survey profiles from the two ends. It was concluded that the contaminant plumes from the oil spillage are yet to be completely degraded as at the time of the study. It is recommended that the contaminated site be remediated to remove or reduce the contaminant oil in the subsurface. 相似文献
3.
Mohammed S. Fnais 《Arabian Journal of Geosciences》2011,4(7-8):1051-1066
Integrated geophysical techniques including resistivity image, vertical electrical sounding (VES), and seismic refraction have been conducted to investigate the Wadi Hanifah water system. The groundwater in Wadi Hanifah has problems caused by the high volumes of sewage water percolating into the ground. The combination of VES, resistivity image, and seismic refraction has made a valuable contribution to the identification of the interface between the contaminated and fresh water in Wadi Hanifah area. The contaminated groundwater has lower resistivity values than fresh groundwater due to the higher concentration of ions which reduces the resistivity. Resistivity image and sounding in this area clearly identified the nature of the lithological depth and proved useful at identifying water-bearing zones. Fresh groundwater was found in the study area at a depth of 100 m within the fractured limestone. Water-bearing zones occur in two aquifers, shallow contaminated water at 10 m depth in alluvial deposits and the deeper fresh water aquifer at a depth of about 100 m in fractured limestone. The interface between the contaminated water (sanitary water) and fresh water marked out horizontally at 100 m distance from the main channel and vertically at 20 m depth. 相似文献
4.
《China Geology》2019,2(4):501-511
With the adjustment of industrial structure, many high pollution enterprises will gradually shut down. This process will produce a large number of high-risk pollution plots and cause a series of environmental problems. In this study, geophysical detection and direct push technology were applied to investigate soil and groundwater pollution in a typical brownfield in Zhenjiang, Jiangsu province, China. The results showed that Chlorotoluene and its ramification were the main pollutants for the brownfield. Pollution decreased with depth and was quite uneven in the brownfield. Production and wastewater treatment areas were heavily polluted, where volatile organic compounds contaminated and semi-volatile organic compounds were found 12 m and 15 m below the land surface, respectively. About 18880 m3 groundwater was contaminated. This study is significant to develop a geological survey work mode for the postindustrial era. 相似文献
5.
Mohamed Metwaly Eslam Elawadi Sayed S. R. Moustafa Nassir Al Arifi Mohamed El Alfy EKab Al Zaharani 《Environmental Earth Sciences》2014,71(2):827-835
Groundwater contamination is one of the most significant problems in arid countries. Al-Quwiy’yia region is an example of an area where the groundwater is contaminated as a result of infiltration of waste water in low-lying areas adjacent to inhabited zones. Such contamination poses significant environmental threats for the surrounding environment and groundwater. Surface observations and spatial distribution of contamination observed in the shallow aquifer indicate that the main contamination sources were from sewage as well as from waste water dumping. However, the main source of water supply for the whole area is groundwater abstracted from the relatively shallow aquifer. Therefore, the transient electromagnetic method (TEM) and 2D electrical resistivity tomography (2D ERT) have been applied close to the waste water dump site to characterize the response of pollution plumes. Both of these geoelectrical techniques are sensitive to electrical conductivity as well as to other physical properties, which are greatly influenced by the polluted groundwater. Therefore, it is possible to profile the contamination plumes, both vertically and horizontally, in the vicinity of the measured stations. The ERT profiles gave detailed information about the lateral distribution of the contaminated groundwater, whereas the TEM demonstrated the vertical extensions. 相似文献
6.
Electrical surveys have routinely been taken to map and monitor groundwater contamination. In 1994-1996, various electrical surveys were applied to investigate contaminant distributions in the ground at the Nanjido landfill. The geophysical survey data were compared with other available information, particularly boring data. Interpretations of electrical survey data show low resistivity zones below 10 ohm-m which appear to be zones fully saturated with leachate. Annual variations of resistivity anomalies clearly indicate that resistivities and thicknesses of layers contaminated by leachate become lower and thicker in and around the Nanjido landfill during one year. In particular, mean thickness of saturated layers with leachate increased by about 3-6 m/year and the resistivity of bedrock decreased. It seems obvious that ground contamination by leachate is in progress. In the area northeast of the landfill, no evidence of bedrock contamination is indicated. Soundings made at one year intervals in this area do not show any evidence of further ground contamination by leachate. From these results, it appears that contamination of the weathered zone and bedrock is in progress mainly southwest of the Nanjido landfill. 相似文献
7.
Robson Willians da Costa Silva Walter Malagutti Filho 《Environmental Earth Sciences》2012,66(5):1371-1383
This paper presents the results of electrical resistivity methods in the area delineation that was potentially contaminated by liquefaction products, which are also called putrefactive liquids in Vila Rezende municipal cemetery, Piracicaba, São Paulo, Brazil. The results indicate a depth of water table between 3.1 and 5.1 m, with two groundwater direction flows, one to the SW and another to the SE. Due to the contamination plumes, which have the same groundwater direction flow, as well the conductive anomalies observed in the geoelectric sections, the contamination suspicions in the area were confirmed. The probable plume to the SE extends beyond the limits of the cemetery. The location of the conductive anomalies and the probable contamination plumes showed that the contamination is linked with the depth of the water table and the burial time. Mapping using the geostatistical method of ordinary kriging applied to the work drew structural characteristics of the regional phenomenon and spatial behavior of the electrical resistivity data, resulting in continued surfaces. Thus, this method has proved to be an important tool for mapping contamination plumes in cemeteries. 相似文献
8.
Hydrochemical and isotopic researches were conducted in El-Sadat City groundwater system to identify groundwater alteration,
recharge, residence time and extent of pollution. The groundwater salinity gradually increases as the groundwater moves from
northeastern to southwestern parts of the city. Groundwater generally shows mineralization decreasing with depth, indicating
that the possibility of recent water penetration far below the surface is limited. Shallow groundwater has an elevated level
of nitrate, which is attributed to anthropogenic sources due to intensive agricultural activity. The limit of high nitrate
water may mark the maximum penetration of groundwater from the surface, which is found in depths <100 m. The northeastern
and southwestern industrial areas are highly contaminated by some heavy metals, which may originate from some local industrial
effluents. The sewage oxidation ponds seem to show no effect on groundwater; hence, these ponds are not a point source for
these heavy metals. Dissolved ions depict five different hydrochemical facies, and stable isotopes define the recharge mechanisms,
the origin of groundwater and the hydraulic confinement of deep groundwater. The deep groundwater is untritiated and has long
residence times (in the order of thousands of years). Three different hydrochemical groups have been recognized and mapped
in El-Sadat City, based on the chemical and isotopic information of the groundwater. These groups have different levels of
contamination. The deep groundwater samples are significantly less impacted by surface activities and it appears that these
important water resources have very low recharge rates and would, therefore, be severely impacted by overabstraction. The
extensive exploitation of groundwater for drinking water supply would shortly be reflected by a gradual decline of the groundwater
table in El-Sadat City. Amelioration of groundwater quality requires further management strategies and efforts in the forthcoming
years. 相似文献
9.
A 480-square-mile region within Will County, in northeastern Illinois, was used as a test region for the development of a methodology to map the sensitivity of aquifers to contamination. An aquifer sensitivity model was developed using a geographic information system (GIS) to overlay and combine several data layers. The components used for our model are: (1) depth to sand and gravel or bedrock, (2) thickness of the uppermost sand and gravel aquifer, (3) glacial drift thickness, and (4) bedrock geology. The model is an improvement over many previous aquifer sensitivity models because it combines specific information on depth to the uppermost aquifer with information on the thickness of the uppermost sand and gravel aquifer. This county-wide model results in an aquifer sensitivity map that can be a useful tool for making land-use planning decisions regarding aquifer protection and management of groundwater resources. 相似文献
10.
11.
Delineation of capture zones for municipal wells in fractured dolomite, Sturgeon Bay, Wisconsin, USA 总被引：1，自引：1，他引：1
A wellhead protection study for the city of Sturgeon Bay, Wisconsin, USA, demonstrates the necessity of combining detailed
hydrostratigraphic analysis with groundwater modeling to delineate zones of contribution for municipal wells in a fractured
dolomite aquifer. A numerical model (MODFLOW) was combined with a particle tracking code (MODPATH) to simulate the regional
groundwater system and to delineate capture zones for municipal wells. The hydrostratigraphic model included vertical and
horizontal fractures and high-permeability zones. Correlating stratigraphic interpretations with field data such as geophysical
logs, packer tests, and fracture mapping resulted in the construction of a numerical model with five high-permeability zones
related to bedding planes or facies changes. These zones serve as major conduits for horizontal groundwater flow. Dipping
fracture zones were simulated as thin high-permeability layers. The locations of exposed bedrock and surficial karst features
were used to identify areas of enhanced recharge. Model results show the vulnerability of the municipal wells to pollution.
Capture zones for the wells extend several kilometers north and south from the city. Travel times from recharge areas to all
wells were generally less than one year. The high seasonal variability of recharge in the study area made the use of a transient
model necessary.
Electronic Publication 相似文献
12.
Gidugu Himakantha D. Mysaiah P. Pavan Kishore K. Satish Kumar K. Dhanam P. Swamy T Seshunarayana H. V. S. Satyanarayana 《Arabian Journal of Geosciences》2017,10(9):216
Geophysical data are needed to correlate the lineaments at the surface to the structural mapping of underlying bedrock. High resolution seismic survey is one of the most suitable geophysical methods for mapping of shallow features. In this study, 2D high resolution seismic reflection survey (HRSS) has been carried out across the Ghaggar, a seasonal river in Haryana, India. The survey is carried out for a profile distance of 10 km across the lineament along the course of Ghaggar River. Ground checks along the river have shown sediments containing alternate layers of alluvium deposits with yellowish silty clay and fine-grained gray sand of variable thickness. Several structural disturbances along the profile are identified. During the quantitative analyses, the results exhibit disturbances in the reflector representing the bedrock. Also, regional gravity data study does not report any major tectonic feature indicating the absence of seismicity associated with the lineament. The present study resulted in that (a) the1.5-km wide zone of disturbance is more likely to be a fracture rather than a major fault across the basement in the depth and (b) the meandering drainage pattern of the Ghaggar River which indicates that it is a basement-controlled lineament. 相似文献
13.
依据实际调查数据,采用单因子污染指数分析法确定了生活垃圾填埋场地下水中主要污染物、污染程度和污染范围,并进行了土壤和地下水污染耦合性分析,研究结果表明：该生活垃圾填埋场地下水污染物主要为氨氮、总氮、高锰酸盐、锰、挥发酚和氟化物,其污染指数最大值分别为1 407.24、745.00、137.12、97.50、3.60和1.68,污染区总面积0.168 km2;填埋场下游沟谷纵向上,总氮、锰两项指标在土壤中的含量与地下水中浓度变化趋势一致;其污染途径主要为库区防渗层破损,渗滤液垂向沿基岩风化裂隙进入地下含水层,以连续渗漏的方式不断污染地下水,污染物在地下水径流作用下向拦挡坝下游不断迁移。 相似文献
14.
为了查明河北省石家庄市近郊污灌区包气带和地下水的污染状况,采用最大可能数法(MPN法)对污灌区水土环境中的常见细菌进行培养,通过铁氧化菌在水土环境中数量的变化及其与各环境因子之间的关系分析得出：研究区铁氧化菌在pH为7.4(中偏碱性)、氧化还原电位(ORP)为318 mV(氧化环境)、温度为15 ℃、溶解氧(DO)质量浓度为4.7~7.8 mg/l、井深40 m的地下水环境中生长较好,数量可达1.1×105 个/ml;铁氧化菌在pH为8.07~8.28、含水量为19.0%~22.9%、岩性为粉土、深度为3.5 m以浅的土壤环境中生长较好,数量可达5.1×107个/g。研究结果表明由于长期污灌,研究区的浅层地下水和上部3.5 m的土壤不同程度地受到污染。铁氧化菌在水土环境中大量繁殖,并不断地把可利用的Fe 2+氧化成不溶性的Fe 3+ ,影响了研究区的水土环境,使研究区的生态环境产生变化。 相似文献
15.
Umar Hamzah Rahman Yaacup Abdul Rahim Samsudin Mohd Shahid Ayub 《Environmental Geology》2006,49(8):1156-1162
A geophysical study was carried out in the Banting area of Malaysia to delineate groundwater aquifer and marine clay layer
of the alluvial Quaternary deposits of Beruas and Gula Formations. The Beruas Formation is formed by peat and clayey materials
as well as silt and sands, whereas the Gula Formation consists of clay, silt, sand and gravels. Both Formations were deposited
on top of the Carboniferous shale of the Kenny Hill Formation. A 2-D geoelectrical resistivity technique was used. Resistivity
measurement was carried out using an ABEM SAS 4000 Terrameter. The 2-D resistivity data of subsurface material for each survey
line was calculated through inverse modelling and then compared with borehole data. The resistivity images of all the subsurface
material below the survey lines show similar pattern of continuous structure of layering or layers with some lenses with resistivity
ranging from 0.1 to 50 Ωm. The upper layer shows resistivity values ranging from 0.1 to 10 Ωm, representing a clay horizon
with a thickness up to 45 m. The second layer with depth varies from 45 to 70 m below surface and has resistivity values ranging
from 10 to 30 Ωm. Borehole data indicate coarse sand with some gravels for this layer, which is also the groundwater aquifer
in the study area. The lowermost layer at a depth of 70 m below ground level shows resistivity values ranging from 30–50 Ωm
and can be correlated with metasedimentary rocks consisting of shale and metaquartzite. 相似文献
16.
A combined geophysical investigation consisting of vertical electrical sounding (VES) and multielectrode system was carried
out to map the subsurface resistivity in all major lakes which are highly polluted by the discharge of sewage and other chemical
effluents in greater Hyderabad, India. The structural features identified in the study area play a major role in groundwater
flow and storage. The interpretation of geophysical data and lithologs indicates that a silt/clay zone (predominantly silt)
has a thickness of 5–10 m all along the drainage from Patelcheruvu to the Musi River. The silt/clay zone inferred close to
the lakes is a mixture of clay, silt and sand with more silt content as indicated from the lithologs during drilling. The
low resistivity values obtained can be attributed to the pollutant accumulated in the silt which can reduce the resistivity
values. Further, the TDS of the water samples in these wells are more than 1,000 mg/l which further confirms the above scenario.
The pollution spread is less in the upstream areas whereas it is more in the downstream which can be attributed to the shallow
water table conditions and also due to the interaction of surface water and groundwater. 相似文献
17.
以江苏港口、泰县、张甸公社、泰兴县、生祠堂镇幅平原区1:50000填图试点为例,围绕深覆盖平原区1:50000基础地质填图的不同深度层次目标任务,采取多种有效技术方法组合,分别对浅表（0~4 m）沉积物、第四纪以来松散层、以及基岩地质等3个深度层次的有效地质填图技术方法进行研究。浅表采用槽型钻+DEM+RS的综合填图方法,第四纪以来松散层采用钻孔、综合地球物理测井相结合的方法建立地层格架,基底地质特征通过区域重磁资料结合浅层地震勘查研究,有效填绘各层次地质信息。基于多种信息源,建立了不同深度、不同精度的多尺度三维地质模型,通过三维建模客观表达多层次地质结构特征,丰富了平原区1:50000填图成果图件体系。最后,探索了不同层次填图成果的应用领域,为平原区1:50000填图的地质图件表达及成果应用提供示范。 相似文献
18.
在遥感解译、野外调查的基础上,采用高密度电法和电阻率测深法,并结合钻探对川西岷江河谷发育的尕米寺滑坡、俄寨村滑坡、格机寨滑坡等典型大型—巨型古滑坡的空间结构进行了勘探分析,有效确定了古滑坡的空间结构和滑带特征,并认为古滑坡的滑动面多具有高低阻相间的不稳定电性层,且滑坡前缘多位于不稳定电性层变薄收敛的地方。其中,俄寨村滑坡高低阻相间的不稳定电性层厚约0~45 m,为滑坡堆积层,古滑动面紧贴基岩面,滑动面平均埋深约30 m,弱风化基岩面埋深约5.6~61 m,强风化层厚约为3~12 m;尕米寺滑坡高低阻相间的不稳定电性层厚约2.5~43 m,为滑坡堆积层,沿剖面古滑动面平均埋深约35 m,在滑坡中部存在一圈闭的低阻异常体,推测为古河道,并与钻探结果相吻合,其埋深约56~96 m,弱风化基岩面埋深13.3~100 m,强风化及岩溶综合层厚一般约为5~20 m。基于古滑坡的地球物理勘探数据和解译结果,统计分析了川西岷江河谷地区大型—巨型古滑坡空间岩土体的地球物理物性参数,对指导该区滑坡调查分析具有重要的指导意义。 相似文献
19.
滹沱河石家庄段地下水污染风险评价 总被引：5，自引：0，他引：5
通过对滹沱河石家庄段污水排放的调查,利用实验测试和恢复费用法对研究区内地下水的污染进行风险评价。研究结果表明,河道内的污水已经污染了地下水．20年的时间段内点污染源和线污染源对地下水的污染面积分别为4．86km^2、16．41km^2,污染体积分别为0．2245×10^8m^3和1．05×10^8m^3。利用恢复费用法,采用2套方案,计算潜在的经济损失分别为2．08×10^8元和0．7×10^8元。 相似文献