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     

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.     

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.     

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.     

Impact of stormwater infiltration basins on groundwater quality, Perth metropolitan region, Western Australia

Twelve bores were sunk adjacent to three stormwater infiltration basins in the Perth metropolitan area to examine the impact of runoff from a light industrial area, a medium-density residential area, and a major arterial road on groundwater quality, and to examine the hydrological response of the aquifer to runoff recharge. Automatic and manual water level monitoring between April and November 1990 indicated that groundwater levels responded within minutes to recharge from the infiltration basins. Peak water levels of up to 2.5 m above rest levels occurred 6–24 h after the commencement of ponding in the infiltration basins. There was a marked reduction in salinity and increase in dissolved oxygen concentrations in the upper part of the aquifer downgradient of the infiltration basins. Concentrations of toxic metals, nutrients, pesticides, and phenolic compounds in groundwater near the infiltration basins were low and generally well within Australian drinking water guidelines. However, sediment in the base of an infiltration basin draining a major road contained in excess of 3500 ppm of lead. Phthalates, which are US EPA priority pollutants, were detected in all but one bore near the infiltration basins. Their detection may be a sampling artifact, but they may also be derived from the plastic litter that accumulates in the infiltration basins. The concentration of iron in groundwater near the infiltration basins appears to be controlled by dissolved oxygen concentrations, with high iron concentrations occurring where dissolved oxygen concentrations are low. Pumping bores located near infiltration basins may suffer from iron encrustation problems caused by the mixing of shallow, oxygenated groundwater with water containing higher concentrations of iron from deeper in the aquifer.     

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.     

Comparison of microbial communities in petroleum-contaminated groundwater using genetic and metabolic profiles at Kyonggi-Do,South Korea

This research has been performed to determine the differences in microbial communities according to physicochemical properties such as concentrations of volatile aromatic hydrocarbons such as benzene, toluene, ethylbenzene, and xylene (BTEX), dissolved oxygen (DO), electron acceptors, etc., in oil-contaminated groundwaters at Kyonggi-Do, South Korea. The properties of bacterial and microbial communities were analyzed by 16S polymerase chain reaction (PCR) denaturing gradient gel electrophoresis (DGGE) fingerprinting method and community-level physiological profiling (CLPP) using Eco-plate, respectively. Based on the DGGE fingerprints, the similarities of bacterial community structures were high with similar DO levels, and low with different DO levels. Whereas the dominant bacterial groups in GW13 (highest BTEX and lowest DO) were acidobacteria, α-proteobacteria, β-proteobacteria, γ-proteobacteria, δ-proteobacteria, and spirochetes, those in GW7 (highest BTEX and highest DO) were actinobacteria, α-proteobacteria, β-proteobacteria, γ-proteobacteria, δ-proteobacteria, and sphingobacteria. Based on the CLPP results, the groundwater samples were roughly divided into three groups: above 4 mg/L in DO (group 1: GW3 and GW7), below 4 mg/L in DO (group 2: GW8, W1, W2, W3, and BH10), and highly contaminated with BTEX (group 3: GW13). Shannon index showed that the microbial diversities and equitabilities were higher in shallower aquifer samples. Overall, this study verified that the greatest influencing factors on microbial/bacterial communities in groundwaters were DO and carbon sources, although BTEX concentration was one of the major factors.     

某石油化工污染场地地下水中挥发性有机物污染特征及成因分析

为了解典型污染场地浅层地下水微量有机污染特征,对西北某省会城市石油化工场地地下水中的挥发性有机污染物（VOCs）污染情况进行了调查。结果表明,污染场地地下水样品中挥发性有机污染物检出率为100%;检出率较高的是氯代烃和苯系物,检出率分别为60%和40%。超标组分为苯和1,2-二氯丙烷,苯超标率为30%,1,2-二氯丙烷超标率10%,苯最大检出浓度达1515μg/L。场地内的原油储存罐、污水隔油池的渗漏以及石油冶炼、机械加工过程工业废水不合理排放均为该场地地下水VOCs的重要来源;VOCs的理化性质以及污染场地地下水防污性能差是影响该场地地下水环境中VOCs归宿的主要因素。     

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.     

Spatial assessment of groundwater quality in the Jangseong region,South Korea

A total of 129 groundwater samples were collected in the Jangseong region of South Korea to characterize and evaluate groundwater quality and its suitability for irrigation and domestic uses. Samples were chemically analyzed for major ions, pH, electrical conductivity, and total dissolved solids following standard methods. The AquaChem 2014.2 model linked with PHREEQC was used for the statistical analysis and characterization of the hydrochemistry of the groundwater. The analysis showed that in all samples Ca–HCO₃ was the leading water type and that the abundance of major cations was in the order Ca > Na > Mg > K, and of anions in the order HCO₃ > Cl > SO₄ > F. According to the correlation analysis, Ca showed strong interdependence with HCO₃, suggesting that these parameters may have originated from common sources. Saturation index calculations indicated that all samples were undersaturated with respect to aragonite, calcite, dolomite, fluorite, gypsum, halite, and siderite, and oversaturated with respect to goethite and hematite. The irrigation suitability analysis revealed that groundwater in the Jangseong area can be used for irrigation without any restrictions based on EC, sodium adsorption ratio, percent sodium, residual sodium carbonate, Kelley ratio, permeability index, and the US Salinity Laboratory diagram analysis. The drinking water suitability analysis made for major parameters by comparison with the WHO guidelines indicates that the groundwater in the area is suitable for drinking except in some samples with high nitrate–N concentrations. The elevated nitrate concentrations in the groundwater are likely an indicator of agricultural pollution.     

Fate and transport of volatile organic compounds in glacial till and groundwater at an industrial site in Northern Ireland

Volatile organic compound (VOC) contamination of subsurface geological material and groundwater was discovered on the Nortel Monkstown industrial site, Belfast, Northern Ireland. The objectives of this study were to (1) investigate the characteristics of the geological material and its influences on contaminated groundwater flow across the site using borehole logs and hydrological evaluations, and (2) identify the contaminants and examine their distribution in the subsurface geological material and groundwater using chemical analysis. This report focuses on the eastern car park (ECP) which was a former storage area associated with trichloroethene (TCE) degreasing operations. This is where the greatest amount of volatile organic compounds (VOCs), particularly TCE, were detected. The study site is on a complex deposit of clayey glacial till with discontinuous coarser grained lenses, mainly silts, sands and gravel, which occur at 0.45–7.82 m below ground level (bgl). The lenses overall form an elongated formation that acts as a small unconfined shallow aquifer. There is a continuous low permeable stiff clayey till layer beneath the lenses that performs as an aquitard to the groundwater. Highest concentrations of VOCs, mainly TCE, in the geological material and groundwater are in these coarser lenses at ∼4.5–7 m bgl. Highest TCE measurements at 390,000 μg L⁻¹ for groundwater and at 39,000 μg kg⁻¹ at 5.7 m for geological material were in borehole GA19 in the coarse lens zone. It is assumed that TCE gained entrance to the subsurface near this borehole where the clayey till was thin to absent above coarse lenses which provided little retardation to the vertical migration of this dense non-aqueous phase liquid (DNAPL) into the groundwater. However, TCE is present in low concentrations in the geological material overlying the coarse lens zone. Additionally, VOCs appear to be associated with poorly drained layers and in peat <3.0 m bgl in the ECP. Some indication of natural attenuation as VOCs degradation products vinyl chloride (VC) and dichloromethane (DCM) also occur on the site.     

Vulnerability of groundwater systems with sea level rise in coastal aquifers, South Korea

Groundwater systems in coastal aquifers may be affected by sea level change as increased seawater intrusion occurs with sea level rise. Artificial pumping taking place at the same time will increase this impact. In order to estimate the vulnerability of groundwater systems with sea level rise within coastal aquifers in South Korea, long-term groundwater data were analyzed using basic statistics, trend analysis, and correlation analysis. Conductivity depth profiling was also periodically conducted. Groundwater levels increased in wells with relatively low groundwater elevations but decreased in wells with higher groundwater elevations. At the same time, conductivity variations were greater in wells located in reclaimed land areas, which vertical conductivity profiles indicated were more affected by sea level variations, but decreased on the mainland. Results of auto-correlation analysis showed a decreasing trend with cyclic variations and significant periodic patterns during dry seasons, indicating that groundwater levels were not affected by artificial factors and that those in reclaimed land areas were less affected by rainfall than on the mainland. These results coincided with those from cross-correlation analysis showing that groundwater level was affected by sea level variation during the dry season. Sea level changes, which may be related to climate change, as well as rainfall in South Korea can influence groundwater levels, and the groundwater system in reclaimed land areas may be more affected than on the mainland, especially under dry conditions.     

GC-MS法测定地下水中28种半挥发性有机物

本文针对地下水监测网运行维护规范(DZ/T 0307-2017)中的半挥发性有机物,建立了一种液/液萃取-气相色谱质谱联用法,可同时测定28种半挥发性有机物(SVOCs),涵盖规范中除多氯联苯外全部的27个SVOCs.方法 采用二氯甲烷萃取,SIM模式经气相色谱质谱联用仪(GC-MS)对样品进行测定,内标法定量,可实现...     

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.     

Distribution of volatile organic compounds around a polluted river

The objectives of this study were to investigate the species and the concentration distribution of volatile organic compounds around a heavily polluted river. Air samples were collected seasonally at different locations near the polluted river. Samples were then analyzed by gas chromatography (electron capture detector for chlorinated organic compounds and flame ionization detector for ordinary hydrocarbons). The data was then analyzed by the statistical product and service solutions software. The results showed that total of 26 species of volatile organic compounds were identified. Each individual had its own concentration distribution pattern at different seasons and aliphatic volatile organic compounds displayed much higher concentrations than most benzenoic volatile organic compounds. In aliphatic volatile organic compounds, 1,2-dibromo-3-chloropropane, hexachlorobutadiene and 1,2-dibromoetane had much higher concentrations at the nearby environment of the river and they have been claimed to be carcinogenic to some experimental animals and possibly to human. Therefore, It is in doubt that for a long term, the volatile organic compounds evaporating out of the stream may threat the health of the residents living very close to the river. The concentrations of tetrachloroethene, 1,1,2,2-tetrachloroethane, hexachlorobutadiene, dibromoetane, dichlorobenzene and sec-butylbenzene appeared at the nearby environment of the river had significant correlations (P < 0.05) with those of each other or many other volatile organic compounds.     

建议纳入地下水调查指标体系的有机污染物——基于迁移性和致病风险的分析

在地下水有机污染调查中,如何准确地选择测试项目,对于正确认识和评价地下水的污染状况是十分必要的.本文通过参照不同标准或规范中所选择的有机指标,依据它们的迁移性和致病风险,从258种有机物中遴选出了29种"地下水污染调查评价规范"(2006)中尚未包括的有机物(主要是除草剂和杀虫剂).建议在进行地下水有机污染调查时,依据当地的污染源情况,增加相应的监测指标,特别是要加强对致病风险高和迁移性较高有机物的重视.     

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.     

Geochemistry of volatile organic compounds in seawater: Mesocosm experiments with 14C-model compounds

A series of ten radiotracer experiments were conducted in controlled experimental ecosystems (mesocosms) to investigate the behavior of volatile organic compounds (VOC) in seawater. Time-series measurements of the redistribution of ¹⁴C-activity within several major pools—dissolved, particulate, intermediate metabolite, and CO₂—in the ecosystem made possible an evaluation of the rates of processes—volatilization, biodegradation, Sorption and sedimentation—acting to remove VOC from seawater in summer. The behavior of the model ¹⁴C-VOC fell into three categories. Aromatic hydrocarbons (benzene, toluene, naphthalene) were subject to both volatilization and biodegradation, with mineralization dominating in summer. Chlorinated C₂-hydrocarbons (tetrachloroethylene) and chlorinated benzenes (chlorobenzene, 1,4-dichlorobenzene, and 1,2,4-trichlorobenzene) were affected only by volatilization and were relatively resistant to biodegradation. Of all the model VOC studied, only aliphatic hydrocarbons (decane and octadecane) were sorbed onto suspended paniculate matter; however, the primary route of loss from the water column appeared to be biodegradation rather than sedimentation. The mesocosm-derived removal rate constants were then applied to estimate summer VOC residence times in Narragansett Bay, Rhode Island of about 1 day for aromatic hydrocarbons, 1 week for the chlorinated VOC and about 1 day for aliphatic hydrocarbons. Residence times in winter might be on the order of 1 week for all VOC.