Comparison of volatile organic compounds in stormwater and groundwater in Seoul metropolitan city,South Korea

Volatile organic compounds (VOCs) detected in stormwater were compared with VOCs present in emission sources, air, groundwater, and influent to sewage treatment plants in Seoul to understand their fate and transport in the urban hydrological system. Stormwater is a carrier of non-point source pollutants and contains VOCs from land surfaces and air. Samples of stormwater and influent to sewage treatment plants were collected and analyzed for 61 VOCs, while the VOCs in emission sources, air and groundwater were investigated through literature reviews for comparison. The results showed that the most frequently detected VOCs in stormwater were similar to those in air. However, the atmospheric concentrations of benzene, toluene, ethylbenzene, and xylenes (BTEX), and methyl tertiary-butyl ether (MTBE) were too low to explain their frequent detection and high concentrations in stormwater. As a result, land surfaces seem to be a primary source of these VOCs in stormwater. Comparison of the VOCs in stormwater and groundwater showed that toluene and MTBE were frequently detected in both media, but more often and at higher concentrations in stormwater. This finding indicates that stormwater recharge is a source of toluene and MTBE in groundwater. Regarding groundwater, land surfaces seem to be a primary source of toluene, while urban air is the primary source in the case of MTBE. Specifically, the MTBE values in air were sufficiently high to explain its levels in groundwater, which had continually increased and remained low afterward. Furthermore, the high ratios of TEX (toluene, ethylbenzene, and xylenes) to benzene and MTBE in stormwater indicated that TEX had additional sources other than vehicles, most likely hydrocarbon solvents. These solvents seem to be a primary source of TEX and other frequently detected VOCs in stormwater. However, trichloroethylene (TCE), tetrachloroethylene (PCE) and their dechlorination intermediates were far more frequently detected and at higher concentrations in groundwater than in stormwater. Additionally, their concentrations frequently exceeded the water-quality criteria. It seems that halogenated solvents had produced contamination plumes of these chlorinated VOCs in the Seoul aquifer. Based on VOCs detected in Seoul, stormwater was mixed with groundwater in combined sewers and flowed into sewage treatment plants. The results imply that organic solvents should be handled with extreme care to protect groundwater quality.     

Residential mobility in the Seoul metropolitan region, Korea

The spatial pattern of residential mobility in Korea is found to be one of intraregional rather than interregional movement. Net inmigration has taken place only in the Seoul metropolitan region (SMR) since 1970. People from the Cholla region have formed the main stream of net inmigration into the SMR. The decentralization of population from Seoul to Kyonggi and Inchon has generated a transformation of the Seoul urban fringe since 1970. This metropolitanization process is accompanied by residential and employment suburbanization to 45kms from the center of Seoul. Residential mobility in the SMR is the result of metropolitan job opportunities, availability of housing, and the effects of the various regional policies. Availability of transportation between Seoul and its urban fringe encouraged the wide expansion of the urban areas and population redistribution within the SMR.     

Urbanization and the groundwater budget, metropolitan Seoul area, Korea

The city of Seoul is home to more than 10 million people in an area of 605 km². Groundwater is abstracted for public water supply and industrial use, and to drain underground facilities and construction sites. Though most tap water is supplied from the Han River, the quantity and quality of groundwater is of great concern to Seoul's citizens, because the use of groundwater for drinking water is continuously increasing. This study identifies the major factors affecting the urban water budget and quality of groundwater in the Seoul area and estimates the urban water budget. These factors include leakage from the municipal water-supply system and sewer systems, precipitation infiltration, water-level fluctuations of the Han River, the subway pumping system, and domestic pumping. The balance between groundwater recharge and discharge is near equilibrium. However, the quality of groundwater and ability to control contaminant fluxes are impeded by sewage infiltration, abandoned landfills, waste dumps, and abandoned wells. Electronic Publication     

北京市深井人工回灌现状调查与前景分析

北京市地下水人工回灌研究始于1965年。1981年开始生产性深井人工回灌。由于种种原因,至1999年底实际回灌单位由64个缩减至13个。其间累计回灌量为10734.37×104t。据调查,停灌原因主要有：回灌单位停产、转产、回灌井被占,回灌井阻塞,泵改调频,单位搬迁和改换制冷设备等。本文通过对北京市三十几年来地下水人工回灌工作的总结,分析了人工回灌在近年来发展停滞的原因,并对其在城市可持续发展建设中的节水潜力和今后的发展前景作出了论述。     

Downtown office location dynamics and transformation of central Seoul, Korea

In recent years, central Seoul has been experiencing a dynamic transformation. In the process of reorganization of the urban industrial structure including tertiarization and quaternarization of the economic base of Seoul, business services are growing very rapidly and large scale urban renewal projects are quickly implemented. Downtown office activities become a nucleus for economic performance of Seoul and high-rise office buildings steer the landscape transformation of central Seoul. Even though there appears to exist some evidence that office districts have dispersed to several subcenters, major office activities are still concentrated in central Seoul. This paper redefines office industry in a narrow sense comprising only relevant economic sectors and office buildings as office activity-functioning units. It then explores the industrial networking and territorial specialization of office activities focusing on the dual process of concentration and dispersion in Seoul. The changing characteristics of the downtown linkages of office activities in this post-industrial era transforms the spatial economy of central Seoul into a more flexible and volatile system, while territorial concentration of power and control functions are fortified at the same time. Finally, the paper addresses the development of manufacturing- tertiary-quaternary industrial complexes, which can be regarded as emerging industrial clusters, producing the cultural economy of urban space and images for clients and customers, in relation to urban competitiveness and territorial specialization of large metropolitan areas. This revised version was published online in July 2006 with corrections to the Cover Date.     

Geoelectrical surveys of the Nanjido waste landfill in Seoul,Korea

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.     

Property-based redevelopment and gentrification: The case of Seoul, South Korea

The urban experiences of South Korea in times of its rapid urbanisation and economic growth show that wholesale redevelopment had been a dominant approach to urban renewal, leading to redevelopment-induced gentrification. This was led by a programme known as the Joint Redevelopment Programme, transforming urban space that was once dominated by informal settlements into high-rise commercial housing estates. This paper tries to explain how this approach was possible at city-wide scale in its capital city, Seoul. Through the examination of redevelopment processes in a case study neighbourhood, it puts forward three arguments. First, the development potential arising from the rent gap expansion through under-utilisation of dilapidated neighbourhoods provided material conditions for the sustained implementation of property-based redevelopment projects. Second, this paper critically examines the dynamics of socio-political relations among various property-based interests embedded in redevelopment neighbourhoods, and argues that external property-based interests have enabled the full exploitation of development opportunities at the expense of poor owner-occupiers and tenants. Third, South Korea had been noted for its strong developmental state with minimum attention to redistributive social policies. The Joint Redevelopment Programme in Seoul was effectively a market-oriented, profit-led renewal approach, in line with a national housing strategy that favoured increased housing production and home-ownership at the expense of local poor residents’ housing needs.     

江阴市河塘镇地裂缝灾害成因分析及防治对策

苏锡常地区地面沉降及地裂缝灾害较为严重,尤其是地裂缝造成的危害较为明显。本文通过对江阴市河塘镇地裂缝分布区的勘查,从地质条件及人为活动两方面剖析了地裂缝的形成原因、发展趋势及相应对策,并对地质灾害的勘查工作提出方向性建议。     

Current water uses,related risks,and management options for Seoul megacity,Korea

Megacities worldwide face various challenging tasks associated with expanding populations and land exploitations; these include securing water supplies, appropriate operating of wastewater treatment/disposal, and the mitigation of natural hazards triggered by anthropogenic activities. Seoul megacity, Korea, where over ten million people populate, is not an exception to the issues. In this study, we examine water resources, their uses, and issues associated with them, specifically climate change, urban flooding, underground water seepage, and land subsidence in Seoul. The changing climate of this city manifests itself in a sharp escalation in air temperature. Increased torrential rainfall causes repeated human casualties from urban floodings, which are exacerbated by expanding impervious surface. The increasingly large interannual variability in precipitation makes it more difficult to take proper actions to secure water supplies. Despite a large annual budget being devoted to producing tap water from the Han River, only about 5% of the population drinks the tap water. Underground transport routes (subway lines) and high storied buildings with deep foundations produce high volumes of underground water seepage, and most of the valuable water resources are dumped without being reused. Underground water seepage also triggers a decline in groundwater levels and elevates the possibility of land subsidence. Recent increases in land subsidence and road sinks in the city are mostly related to old sewer lines and heavy underground work. In this study, we discuss options toward supporting sustainable urban water management in Seoul.     

Hydrochemistry of urban groundwater in Seoul, South Korea: effects of land-use and pollutant recharge

The ionic and isotopic compositions (δD, δ¹⁸O, and ³H) of urban groundwaters have been monitored in Seoul to examine the water quality in relation to land-use. High tritium contents (6.1–12.0 TU) and the absence of spatial/seasonal change of O–H isotope data indicate that groundwaters are well mixed within aquifers with recently recharged waters of high contamination susceptibility. Statistical analyses show a spatial variation of major ions in relation to land-use type. The major ion concentrations tend to increase with anthropogenic contamination, due to the local pollutants recharge. The TDS concentration appears to be a useful contamination indicator, as it generally increases by the order of forested green zone (average 151 mg/l), agricultural area, residential area, traffic area, and industrialized area (average 585 mg/l). With the increased anthropogenic contamination, the groundwater chemistry changes from a Ca–HCO₃ type toward a Ca–Cl(+NO₃) type. The source and behavior of major ions are discussed and the hydrochemical backgrounds are proposed as the basis of a groundwater management plan.     

Application of statistical geo-spatial information technology to soil stratification in the Seoul metropolitan area

Typical geotechnical testing results reflect the level of soil uncertainty, which requires statistical corrections of the data for an appropriate engineering decision. This study proposes frameworks to detect outlying data points using statistical analyses, the cross-validation-based method and the generalised extreme value distribution-based method. The borehole data regarding soil depth distribution in a central area of Seoul, South Korea are assessed to validate the aforementioned methods for comparison with the distribution-based method and the Moran scatterplot method. The results show that the proposed methods enable more reliable spatial distributions to be achieved with a quantitative evaluation of local reliability.     

Hydrochemistry and quality assessment of groundwater in part of NOIDA metropolitan city,Uttar Pradesh

An attempt has been made to study the groundwater geochemistry in part of the NOIDA metropolitan city and assessing the hydrogeochemical processes controlling the water composition and its suitability for drinking and irrigation uses. The analytical results show that Na and Ca are the major cations and HCO₃ and Cl are the major anions in this water. The higher ratios of Na+K/TZ⁺ (0.2–0.7), Ca+Mg/HCO₃ (0.8–6.1); good correlation between Ca-Mg (0.75), Ca-Na (0.77), Mg-Na (0.96); low ratio of Ca+Mg/Na+K (1.6), Ca/Na (1.03), Mg/Na (0.64), HCO₃/Na (1.05) along with negative correlation of HCO₃ with Ca and Mg signify silicate weathering with limited contribution from carbonate dissolution. The hydro-geochemical study of the area reveals that many parameters are exceeding the desirable limits and quality of the potable water has deteriorated to a large extent at many sites. High concentrations of TDS, Na, Cl, SO₄, Fe, Mn, Pb and Ni indicate anthropogenic impact on groundwater quality and demand regional water quality investigation and integrated water management strategy. SAR, %Na, PI and Mg-hazard values show that water is of good to permissible quality and can be used for irrigation. However, higher salinity and boron concentration restrict its suitability for irrigation uses at many sites.     

Hydrogeological studies on the mechanical behavior of landfill gases and leachate of the Nanjido Landfill in Seoul, Korea

 The Nanjido Landfill is the largest uncontrolled landfill in Korea and it causes various kinds of environmental problems. Landfill gases and leachate are recognized as the most serious environmental problems associated with the landfill. This study employs a series of numerical models and uses test data to interpret the distribution and flow of landfill gases and leachate. Leachate seepage appears about 40–60 m higher than the estimated basal groundwater table. Thus, seepage data indicate that perched or floating leachate layers are formed in the unsaturated zone of the landfill. The leachate production rate is estimated using infiltration test data and a model for unsaturated groundwater flow. Geochemical data indicate that the landfill leachate degrades the basal groundwater quality along the downgradient zone. The environmental impact of the leachate on river water is estimated. Received: 17 June 1996 · Accepted: 2 October 1996     

综合物探方法在广州市金沙洲岩溶地面塌陷、地面沉降地质灾害调查中的应用

综合运用跨孔地震CT、探地雷达、高密度电阻率法、浅层地震反射波、土壤氡浓度和波速测试6种物探方法,对广州市白云区金沙洲岩溶地面塌陷、地面沉降地质灾害进行探测,查明了该区的溶洞、土洞及构造破碎带的分布。介绍了各种方法技术,对综合物探成果进行总结,结合实例说明综合物探方法在该区的应用取得了显著效果,为地质灾害防治提供了基础地质资料。在广花盆地岩溶发育区,首次应用跨孔地震CT探测建筑物地下岩溶分布,为评价受岩溶地质灾害影响的建筑物安全提供依据。     

广州岩溶地区深基坑开挖对周围环境影响的研究

以广州地铁9号线在岩溶地区施工深基坑为例,研究岩溶地层基坑施工对周围环境的影响。该车站基坑长259.7 m,宽18.7 m,深15.8 m。基坑深度范围内包括溶洞和砂层,溶洞地层富水、稳定性差、物理力学性质差,砂层厚0～15 m,有较大的渗透性,基坑施工过程中对地下连续墙的侧向位移和地面沉降进行了监测。监测结果表明,基坑开挖结束时地下连续墙的最大侧向位移为12 mm,地面沉降的最大值为10.1 mm,基坑开挖过程中对周围环境的影响很小。研究成果可为今后类似工程施工提供经验借鉴。     

我国城市地裂缝灾害问题与对策

从20世纪中期以来地裂缝在我国许多城市开始出现，已成为一种区域性的重要地质灾害，严重危及城市建设与人民生活。文章详细介绍了我国地裂缝灾害的分布特征，总结出地裂缝具有成带性、不可抗拒性、方向性和周期性的灾害特点。以我国比较典型的新构造活动区域－汾渭地堑内的地裂缝为例，从构造活动和地下水开采影响方面分析了地裂缝形成机理，针对地裂缝产生的不同原因，提出了建筑物加固和减少地下水开采等控制及减轻地裂灾害的措施。     

Effects of land use on the spatial distribution of trace metals and volatile organic compounds in urban groundwater, Seoul, Korea

To investigate the urban groundwater contamination by eight trace metals and 69 volatile organic compounds (VOCs) in relation to land use in Seoul, a total of 57 groundwater samples collected from wells were examined using a non-parametric statistical analysis. Land use was classified into five categories: less-developed, residential, agricultural, traffic, and industrial. A comparison of analyzed data with US EPA and Korean standards for drinking water showed that some metals and VOCs exceeded the standards in a few localities, such as Fe (N=5), Mn (N=6), Cu (N=1), TCE (N=6), PCE (N=8), 1,2-DCA (N=1), and 1,2-dichloropropane (N=1). Among the 69 investigated VOCs, 19 compounds such as some gasoline-related compounds (e.g., toluene) and chlorinated compounds (e.g., chloroform, PCE, TCE) were detected in groundwater. Non-parametric statistical analysis showed that the concentrations of most trace metals (Fe, Mn, As, Cr, Pb, Cd) and some VOCs (especially, TCE, PCE, chloroform; toluene, carbon tetrachloride, bromodichloromethane, CFC113) are significantly higher in the industrial, residential, and traffic areas (P<0.05), indicating that anthropogenic contamination of urban groundwater by those chemicals is growing. Those chemicals can be used as effective indicators of anthropogenic contamination of groundwater in urban areas and therefore a special attention is warranted for a safe water supply in those areas. The results of this study suggest that urban groundwater quality in urban areas is closely related with land use.     

Prediction of ground subsidence in Samcheok City,Korea using artificial neural networks and GIS

This study shows the construction of a hazard map for presumptive ground subsidence around abandoned underground coal mines (AUCMs) at Samcheok City in Korea using an artificial neural network, with a geographic information system (GIS). To evaluate the factors governing ground subsidence, an image database was constructed from a topographical map, geological map, mining tunnel map, global positioning system (GPS) data, land use map, digital elevation model (DEM) data, and borehole data. An attribute database was also constructed by employing field investigations and reinforcement working reports for the existing ground subsidence areas at the study site. Seven major factors controlling ground subsidence were determined from the probability analysis of the existing ground subsidence area. Depth of drift from the mining tunnel map, DEM and slope gradient obtained from the topographical map, groundwater level and permeability from borehole data, geology and land use. These factors were employed by with artificial neural networks to analyze ground subsidence hazard. Each factor’s weight was determined by the back-propagation training method. Then the ground subsidence hazard indices were calculated using the trained back-propagation weights, and the ground subsidence hazard map was created by GIS. Ground subsidence locations were used to verify results of the ground subsidence hazard map and the verification results showed 96.06% accuracy. The verification results exhibited sufficient agreement between the presumptive hazard map and the existing data on ground subsidence area. An erratum to this article can be found at