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1.
A geochemical assessment of groundwater quality and possible contamination in the vicinity of the Bhalswa landfill site was carried out by using a hydrochemical approach with graphical and multivariate statistical methods with the objective of identifying the occurrence of various geochemical processes and understanding the impact of landfill leachates on groundwater quality. Results indicate that nitrate, fluoride and heavy-metal pollution are in an alarming state with respect to the use of groundwater for drinking purposes. Various graphical plots and statistical analyses have been applied to the chemical data based on the ionic constituents, water types, and hydrochemical facies to infer the impact of the landfill on groundwater quality. The statistical analysis and spatial and temporal variations indicate the leaching of contaminants from the landfill to the groundwater aquifer system. The concentrations of heavy metals in the landfill leachates are as follows: Fe (22 mg/l), Mn (~20 mg/l), Cu (~10 mg/l), Pb (~2 mg/l), Ni (0.25 mg/l), Zn (~10 mg/l), Cd (~0.2 mg/l), Cl− (~4,000 mg/l), SO42− (~3,320 mg/l), PO43− (~4 mg/l), NO3− (30 mg/l) and fluoride (~50 mg/l); all were much higher than the standards. The study reveals that the landfill is in a depleted phase and is affecting groundwater quality in its vicinity and the surrounding area due to leaching of contaminants.  相似文献   

2.
Zhan  Liangtong  Wu  Linbo  Han  Hua  Zhang  Shuai  Zhou  Honglei  Song  Xue  Zhao  Li  Guo  Qimeng  Chen  Yunmin 《Hydrogeology Journal》2023,31(3):771-787

Tens of thousands of municipal solid waste (MSW) landfill sites worldwide hold a high risk of contaminating groundwater. This study aimed to establish a practical hydrogeological classification system for MSW landfill sites and explores the correlation between the classification and the risk of groundwater contamination. Hydrogeological information and groundwater contamination data from 80 MSW landfill sites in China were collected and analyzed, and a general hydrogeological model was proposed. The key hydrogeological parameters in the model were identified and analyzed, including the relative depth to the water table, the ratio of the length of the MSW site’s recharge boundary to the combined length of the discharge boundary and hydrobalance boundary, the hydraulic conductivity of the bearing layer, and the background hydraulic gradient. On the basis of the general model, hydrogeological conditions at the landfill sites were categorized into seven subtypes. By using chloride, ammoniacal nitrogen and chemical oxygen demand as the characteristic contaminants, the migration features of groundwater contaminants within the seven subtypes of landfill sites were revealed. It was found that the maximum contaminant migration distance could be 2,000 and 300 m at the landfill sites with ‘plain and intensive runoff’ type and ‘valley and weak runoff’ type, respectively, and the corresponding concentration gradients of the characteristic contaminants were less than 10 mg/(L × m) and greater than 10 mg/(L × m). This work provides a guide for implementing cost-effective site investigation and environmental risk management at landfill sites with different types of hydrogeological conditions.

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3.
 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  相似文献   

4.
The effect of the Ruseifa municipal landfill on the shallow groundwater aquifers in the area was investigated in two separate sites. The first one was not used since 1994, whereas the other is still being used for dumping. Fourteen electrical resistivity soundings were performed to detect the leachate and its effect on the quality of the groundwater. Results indicated that the solid waste thickness of the landfill was ranged from 3 to 20 m with resistivity value less than 10 Ω m. Based on the resistivity decreases of values less than 5 Ω m, the leachate was detected in the landfill sites at depths ranged from 10 to 50 m. However, the flow direction of the leachate at depth ranging 10–20 m in the terminated site was toward north, whereas the flow direction of the leachate in the site still used for dumping was toward east–northeast which causes the major source of groundwater pollution.  相似文献   

5.
The El Jadida landfill is one among many uncontrolled dumping sites in Morocco with no bottom liner. About 150 tons/day of solid wastes from mixed urban and industrial origins are placed directly on the ground. At the site of this landfill, the groundwaters circulate deeply (10–15 m) in the Cenomanian rock (calcareous–marl), which is characterised by an important permeability from cracks. The soil is sand–clay characterized by a weak coefficient of retention.The phreatic water ascends to the bottom of three quarries, which are located within the landfill. These circumstances, along with the lack of a leachate collection system, worsen the risks for a potential deterioration of the aquifer.To evaluate groundwater pollution due to this urban landfill, piezometric level and geochemical analyses have been monitored since 1999 on 60 wells. The landfill leachate has been collected from the three quarries that are located within the landfill. The average results of geochemical analyses show an important polluant charge vehiculed by landfill leachate (chloride = 5680 mg l−1, chemical oxygen demand = 1000 mg l−1, iron = 23 000 μg l−1). They show also an important qualitative degradation of the groundwater, especially in the parts situated in the down gradient area and in direct proximity to the landfill. In these polluted zones, we have observed the following values: higher than 4.5 mS cm−1 in electric conductivity, 1620 and 1000 mg l−1 respectively in chlorides and sulfate (), 15–25 μg l−1 in cadmium, and 60–100 μg l−1 in chromium. These concentrations widely exceed the standard values for potable water.Several determining factors in the evolution of groundwater contamination have been highlighted, such as (1) depth of the water table, (2) permeability of soil and unsaturated zone, (3) effective infiltration, (4) humidity and (5) absence of a system for leachate drainage. So, to reduce the pollution risks of the groundwater, it is necessary to set a system of collection, drainage and treatment of landfill leachates and to emplace an impermeable surface at the site of landfill, in order to limit the infiltration of leachate.  相似文献   

6.
The study of hydrogeochemistry of the Mio-Pliocene sedimentary rock aquifer system in Veeranam catchment area produced a large geochemical dataset. Groundwater samples were collected at 52 sites over 963.86 km2 area and analyzed for major ions. The large number of data can lead to difficulties in the integration, interpretation and representation of the results. Two multivariate statistical methods, Hierarchical cluster analysis (HCA) and Factor analysis (FA), were applied to a subgroup of the dataset to evaluate their usefulness to classify the groundwater samples, and to identify geochemical processes controlling groundwater geochemistry. Hydrochemical data for 52 groundwater samples were subjected to Q- and R- mode factor and cluster analysis. R-mode analysis reveals the inter-relations among the variables studied and the Q-mode analysis reveals the inter-relations among the samples studied. The R-mode factor analysis shows that Ca, Mg and Cl with HCO3 account for most of the electrical conductivity, total dissolved solids and total hardness of groundwater. The ‘single dominance’ nature of the majority of the factors in the R-mode analysis indicates non-mixing or partial mixing of different types of groundwater. Both Q-mode factor and Q-mode cluster analyses indicate an exchange between the river water and the groundwater in the vicinity. The rock water interaction like flood basin back swamp deposits of silty clayey formation is the major cause for the cluster II classification. Cluster classification map reveals that 58% of the study area comes under cluster II classification.  相似文献   

7.
Present study is an effort to distinguish between the contributions of natural weathering and anthropogenic inputs towards high salinity and nutrient concentrations in the groundwater of National Capital Territory (NCT) Delhi, India. Apart from the source identification, the aquifer of entire territory has been characterized and mapped on the basis of salinity in space and water suitability with its depth. Major element chemistry, conventional graphical plots and specific ionic ratio of Na+/Cl−, SO4 2−/Cl−, Mg2+/Ca2+ and Ca2+/(HCO3 − + SO4 2−) are conjointly used to distinguish different salinization sources. Results suggest that leaching from the various unlined landfill sites and drains is the prime cause of NO3 − contamination while study area is highly affected with inland salinity which is geogenic in origin. The seasonal water level fluctuation and rising water level increases nutrients concentration in groundwater. Mixing with old saline sub-surface groundwater and dissolution of surface salts in the salt affected soil areas were identified as the principle processes controlling groundwater salinity through comparison of ionic ratio. Only minor increase of salinity is the result of evaporation effect and pollution inflows. The entire territory has characterized into four groups as fresh, freshening, near freshening and saline with respect to salinity in groundwater. The salinity mapping suggests that in general, for drinking needs, groundwater in the fresh, freshening and near freshening zone is suitable up to a depth of 45, 20 and 12 m, respectively, while the saline zones are unsuitable for any domestic use. In the consideration of increasing demand of drinking water in the area; present study is vital and recommends further isotopic investigations and highlights the need of immediate management action for landfill sites and unlined drains.  相似文献   

8.
Attenuation characteristics of landfill leachate were examined for two uncontrolled landfills in Korea. The two landfills containing municipal wastes without appropriate bottom liner and leachate treatment system have different landfill age, waste volume, and most importantly different hydrogeologic settings. One landfill (Cheonan landfill) is situated in an open flat area while the other (Wonju landfill) is located in a valley. Variations of various parameters including dissolved organic carbon (DOC), dissolved oxygen (DO), alkalinity, pH, electrical conductivity (EC), redox potential (ORP), ammonia (NH3), nitrate (NO3−), sulfate (SO42−), and chloride (Cl−) were examined along groundwater flow path. All these parameters were analyzed every month for a year. In the interior of the landfills, typical anaerobic conditions revealed by low DO and NO3 concentrations, negative ORP values, high NH3, alkalinity, and Cl− concentrations were observed. Generally, higher levels of contaminants (DOC, NH3, and Cl−) were detected in the dry season while they were greatly lowered in the wet season. Significantly, large decrease of Cl- concentration in the wet season indicates that the dilution or mixing is one of dominant attenuation mechanisms of leachate. But detailed variation behaviors in the two landfills are different and they were largely dependent on permeability of surface and subsurface layers. The intermediately permeable surface of the landfills receives part of direct rainfall infiltration but most rainwater is lost to fast runoff. The practically impermeable surface of clayey silt (paddy field) at immediately adjacent to the Cheonan landfill boundary prevented direct rainwater infiltration and hence redox condition of the ground waters were largely affected by that of the upper landfill and the less permeable materials beneath the paddy fields prohibited dispersion of the landfill leachate into down gradient area. In the Wonju landfill, there are three different permeability divisions, the landfill region, the sandy open field and the paddy field. Roles of the landfill and paddy regions are very similar to those at the Cheonan. The very permeable sandy field receiving a large amount of rainwater infiltration plays a key role in controlling redox condition of the down gradient area and contaminant migration. This paper reports details of the attenuation and redox conditions of the landfill leachates at the two uncontrolled landfills.  相似文献   

9.
Results of comprehensive geochemical mapping and thematic studies of the Slovak territory (rocks, soils, stream sediments, groundwaters, biomass, and radioactivity) in the first half of the 1990s led to several new research programmes in Slovakia, within the frame of which new methodologies for geochemical data evaluation and map visualization were elaborated. This study describes the application and elaboration of data from the Geochemical Atlas of the Slovak Republic at national and regional levels. Based on the index of environmental risk (IER = ΣPEC/PNEC), the level of contamination for the geological component of the environment in Slovakia was evaluated. Approximately 10.5% of Slovakia’s territory was characterized as being environmentally disturbed to highly disturbed. In the areas where environmental loadings have accumulated, 14 regions where environmental risks existed due to high element concentrations were defined. The model calculations of health risk estimates based on the databases of the Geochemical Atlas for groundwater and soils indicate that the possible risk occurrence of carcinogenic diseases from groundwater arsenic contents is high in more than 10% of Slovakia, whereas the chronic risk is negligible. To determinate the background and threshold levels a combined statistical–geochemical approach was developed and applied as an example for groundwater at the national level as well as for single groundwater bodies. The results of statistical method application for the whole groundwater body (GBW) were compared with the background values for anthropogenically non-influenced areas in GBW. Final background value took into account time variations and spatial distribution of the element in GBW. Furthermore, based on the database from the Geochemical Atlas for groundwater, groundwater bodies potentially at qualitative risk were delineated for the whole of Slovakia. From a total of 101 groundwater bodies 17 were characterized as being at risk and 22 as being at possible risk.  相似文献   

10.
The groundwater quality detoriation due to various geochemical processes like saline water intrusion, evaporation and interaction of groundwater with brines is a serious problem in coastal environments. Understanding the geochemical evolution is important for sustainable development of water resources. A detailed investigation was carried out to evaluate the geochemical processes regulating groundwater quality in Cuddalore district of Tamilnadu, India. The area is entirely underlined by sedimentary formations, which include sandstone, clay, alluvium, and small patches of laterite soils of tertiary and quaternary age. Groundwater samples were collected from the study area and analyzed for major ions. The electrical conductivity (EC) value ranged from 962 to 11,824 μS/cm, with a mean of 2802 μS/cm. The hydrogeochemical evolution of groundwater in the study area starts from Mg-HCO3 type to Na-Cl type indicating the cation exchange reaction along with seawater intrusion. The Br/Cl ratio indicates the evaporation source for the ion. The Na/Cl ratios indicate groundwater is probably controlled by water-rock interaction, most likely by derived from the weathering of calcium-magnesium silicates. The plot of (Ca+Mg) versus HCO3 suggests ions derived from sediment weathering. The plot of Na+K over Cl reflects silicate weathering along with precipitation. Gibbs plot indicates the dominant control of rock weathering. Factor analysis indicates dominance of salt water intrusion, cation-exchange and anthropogenic phenomenon in the study.  相似文献   

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