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1.
Removal of trace elements from landfill leachate by calcite precipitation   总被引：1，自引：0，他引：1  
Spontaneous precipitation of secondary calcite (CaCO3) has been observed in 25 samples of landfill leachate-polluted stream waters. During the 6-month precipitation experiment, the formation of calcite acts as a principal trace-element scavenging process. The concentrations of Fe, Sr, Ba and Mn and other trace elements in solution significantly decreased as calcite formed during the experiments. The PHREEQC-2 geochemical code indicated high supersaturation of the initial leachate-polluted waters with respect to calcite. The chemical/mineralogical study (SEM/EDS, XRD, ICP MS) revealed that this newly formed calcite contains considerable amounts of metals and metalloids removed from solution. Such a geochemical process can be considered to be important for spontaneous decontamination in landfill-affected environments (stream sediments, soils) or landfill technical facilities (settling basins). This removal takes place especially during dry periods with low rain precipitation, when the landfill waters exhibit both higher alkalinity and higher trace element concentrations.  相似文献   

2.
The capital city of Botswana, Gaborone, has seen unprecedented population, economic, and industrial growth in recent years. In order to assess how this rapid urbanisation process impacts the environment, 106 silt and clay (particle size <0.053 mm) samples, separated from Gaborone surface soil samples representing urban, agricultural and rural sites, were investigated. The concentrations of nine heavy metals (Sc, Cr, Co, Ni, Cu, Zn, Nb, Cd, and Pb) were measured using ICP–MS and GFAAS, and the resulting patterns were correlated to the bedrock composition and anthropogenic activities. As expected, we found that samples from soils on top of dolerites show higher levels of Cr, Ni, and Cu than those on top of granites and rhyolites. However, our studies also show that Gaborone city centre soils are moderately polluted by Pb (up to 222 mg/kg, i.e. 5.7-fold the concentration in comparable rural soils), as a result of heavy traffic. Furthermore, Cr and Ni pollution originating from agrochemicals were shown to be accumulating in Gaborone crop soils. Our studies also showed moderate levels of Zn pollution and low level, dot-shaped pollution of Cr, Co, Ni, Cu detected in Gaborone residential and industrial soils that are correlated to waste disposal. Interestingly, the highest levels of Sc, Cr, Co, Ni and Zn pollution are found near two abandoned sewage works. The results of sequential extraction indicate that the polluting Co and Ni exist in all speciations; the polluting Cu mainly exists in the residue of the sequential extraction, whereas the polluting Pb is mostly bound to organic matters and Fe- and Mn-oxides. These results highlight the need for instituting a systematic and continuous monitoring of heavy metals and other forms of pollutants in Gaborone to ensure that pollution does not become a serious problem in the future.  相似文献   

3.
Mondal  Manishree  Chakraborty  Chayon 《GeoJournal》2022,87(4):607-630

An unparalleled struggle has been witnessed among the urban women informal workers of Midnapore and Kharagpur cities in West Bengal, India. Many researchers have advocated and are advocating about the deadly impact of COVID-19 pandemic situation on the women informal workers but very few were concentrated on their coping capabilities. These women in the study area have set an example before others that how can one survive her livelihood in the time of critical situation. Despite all the hardships they have been fighting their own lonely battle not only against this situation but also a lot of serious threats like insecurity, low resources and low standard of living. This study mainly highlights the measures taken by these poor women to cope with this situation for the survival of their families along with the external supports provided for them. This is strictly a perception based study conducted among 500 women selected by purposive sampling procedure across age, ethnicity, income and educational level during unlock phases with the help of semi-structured and open ended questionnaire schedule. The result reveals that although their capabilities and efforts to cope with this devastating situation are praiseworthy but it is a hard reality that this pandemic put its evil imprint in every step of their daily livelihoods. The various measures have already been taken by the government but, these measures have to be continued till the situation will become normal along with gender sensitive long term benefit.

  相似文献   

4.
Increase in waste generation calls for an effective waste management as this has become a necessity for environmental sustainability. Several methods are adopted in managing waste, which include waste reduction, reuse, thermal treatment, recycling and landfilling. The landfill method is recognised as the most used of all the waste management methods in developing countries such as Ghana. However, the selection of a suitable landfill site is very difficult and tedious. This is because it involves a consideration of many factors such as environmental, topographic, economic, socio-cultural and civil engineering. This research sought to identify a suitable landfill site by applying GIS multicriteria and weighted overlay approach in the Bongo District of Northern Ghana. The analysis relied on criteria and weights provided by the technocrats and the indigenes in the district as a way of demonstrating how landfill siting impasse can be resolved by incorporating the various stakeholders. The results obtained provided clear areas for landfill sites in the study area from the technocratic and the indigenous perspectives. However, the technocratic perspective failed to include an important cultural criterion, sacred groves, as a factor. The indigenous perspective also compromised on the factor related to nearness to residential areas, and is equally not sufficient on its own. The optimal landfill sites, which meets the expectations of both the technocrats and indigenes, was identified. This perspective has produced technically favourable and socio-culturally acceptable landfill site. However, it is recommended an environmental impact assessment (EIA) be conducted to identify the full environmental and social cost of the site. It is concluded that in landfill site selection much attention be given to cultural factors in the same way as the technical factors.  相似文献   

5.
 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   

6.
This study investigates the utilization of landfill biogas as a fuel for electrical power generation. Landfills can be regarded as conversion biogas plants to electricity, not only covering internal consumptions of the facility but contributing in the power grid as well. A landfill gas plant consists of a recovery and a production system. The recovery of landfill gas is an area of vital interest since it combines both alternative energy production and reduction of environmental impact through reduction of methane and carbon dioxide, two of the main greenhouse gases emissions. This study follows two main objectives. First, to determine whether active extraction of landfill gas in the examined municipal solid waste sites would produce adequate electric power for utilisation and grid connection and second, to estimate the reduction of sequential greenhouse gases emissions. However, in order to optimize the designing of a plant fed by biogas, it is necessary to quantify biogas production over several years. The investigation results of energy efficiency and environmental impact of biogas utilization in landfills are considering satisfactory enough both in electric energy production and in contribution to greenhouse gases mitigation.  相似文献   

7.
Environmental management of coastal regions in the Caspian Sea   总被引：13，自引：13，他引：0  
Considering rapid population growth and migration, higher accumulation of communities is noticed in coastal areas. This is especially true with the coastal areas of the Caspian Sea. In the present investigation coastal areas between Jouybar to Behshahr region is selected for their special geographical and ecological locations. Further, adverse impacts of human, agriculture and industrial activities was examined along side the above mentioned coasts. It should be pointed out that protected Miankaleh Wildlife zone which is an internationally recognized wetland, falls within area of study. In the present study strengths, weaknesses, opportunities and threats method is used for the evaluation of environmental management status. In this regard, internal and external factors gained 2.28 and 2.58 scores. This is indicative of the abundance of weaknesses over strengths and it also shows that opportunities are more than threats. Subsequently 27 strategies were developed and quantitative strategic planning matrix method was also used to score each strategies. The results of quantitative strategic planning matrix method analysis was programmed in strategic position and action evaluation matrix. The present situation falls within “competitive” classification. This is indicative of weakness in coordinating development and environmental strategic plans. The result of present investigation strongly emphasis on compilation of strategic environmental plans for the control of population, pollution emission and land use planning changes. The most important strategies include development of environmental regulations and better supervision on enforcement of laws.  相似文献   

8.
Climate change presents both threats and opportunities to the nations and peoples of central and eastern Europe. National and international programs are directly addressing climate change, and other programs speak to natural resource and environmental quality issues that will have significant effects on vulnerability and adaptation to climate change. This paper explores examples of ongoing climate change activity in the region, setting a broad context for the subsequent papers in this volume ofGeoJournal. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

9.
The study of landfill sites is one of the most important studies in landfill engineering, and the landfill site selection involves combination of engineering, science, and politics. This paper describes a comprehensive hazardous waste landfill site selection methodology with the combined utilization of geographic information system and multiple criteria analysis methods, as applied to the Zanjan province in Iran. The six main data categories that were used are geological/engineering geological, geomorphological, hydrological/hydrogeological, climatological, pedological, and social/economical criteria, which included 31 input layers in total. A suitability map for hazardous waste landfilling was prepared for study area with five classes from most suitable to completely unsuitable. Finally, out of the three sites, one site was selected which was chosen by the local authorities. Our work offers a comprehensive methodology and provides essential support for decision-makers in the assessment of hazardous waste management problems in Zanjan province in I.R. Iran and other developing cities in other countries.  相似文献   

10.
This case study investigates peri-urban land-use conflicts and changes, in a typical African setting, for a village located on the outskirts of the capital city of Gaborone-Botswana, in order to explore policy implications for sustainable core-region development. The year 1982 provided the baseline situation that was compared with other dates, namely: 1996; 2006 and 2012 in order to analyze land-use conflicts, competition, and succession. The study tracked the landuse changes using: Geographic Information System (GIS), with 1:50 000 air photos taken in 1982; Landsat images from 1996 and 2006 as well as 2012 Google images of medium resolution. The investigation also relied on a social survey, historical landscape reconstruction approaches, field interviews and direct observations. An analysis of 1982 aerial photographs revealed that Gabane Village had experienced little urban influence from the city of Gaborone at that time. Subsequently, stakeholders with different socio-economic demand emerged. This caused extensive land-use changes over the study period. The residents of Gabane nonetheless employed diverse adaptive strategies to sustain their livelihoods. An analysis of the proposed 2001-2025 Development Plan for Gabane Village, identifies possible future land-use changes and conflicts and proposes tentative policy solutions for the emerging sustainable development challenges.  相似文献   

11.
Multi-matrix environmental monitoring was used to evaluate the influence of a municipal solid waste landfill (Ginestreto, Emilia Romagna, Italy) on the level and distribution of heavy elements in the surrounding environment (air, soil and soil biota). Concentrations of As, Cd, Co, Cr, Cu, Hg, Ni, Pb, Sb, Tl and Zn were measured by inductively coupled plasma-mass spectrometry in transplanted lichens, topsoils and isopods. The highest accumulation levels found for Cd, Cr, Pb, Sb and Zn in lichens transplanted within the Ginestreto landfill. However, similar concentrations of these heavy elements were also found in lichens exposed in monitoring sites influenced by other man-made sources, such as vehicle traffic and truck movements. The fallout of heavy elements emitted by the landfill had low impact on their levels in topsoil: Cd, Cr, Pb, Sb and Zn showed higher contents in topsoil collected close to the landfill and a slight decrease in concentrations with increasing distance from the landfill. There was no variation in heavy element accumulation in isopods in relation to distance from the landfill. The results of this study indicate that the Ginestreto municipal solid waste landfill had limited impact on the environmental distribution of heavy elements, since accumulation and enrichment in lichens and topsoils were only detected close to the landfill, up to about 100 m from its border.  相似文献   

12.
The purpose of this study was to determine if metal concentrations are enriched in two size sediment fractions of streams that receive landfill effluent and, if so, whether there is a greater extent of metal enrichment in one of the fractions. Sediment samples were collected from three streams adjacent to a sanitary landfill. Sediments representing control for the study were also collected from a stream not influenced by the landfill. All samples were sieved and the <0.0625-mm and <0.25-mm to >0.149-mm size fractions from each sample were used in this study. The concentrations of acid-extractable Cu, Zn, Pb, and Cr for all samples were determined by atomic absorption techniques. Mean concentrations, coefficient of variation values, at test, and the variation of metal concentrations along the stream were used to analyze the data. Results indicated that Cu, Zn, Pb, and Cr concentrations were enriched in both size sediment fractions from the stream whose channel originated at the base of the landfill. Copper, Zn, and Pb concentrations were enriched in the <0.0625-mm size sediments of the stream whose channel did not intersect the landfill. Copper, Zn, Pb, and Cr concentrations appear enriched in both size sediment fractions of the third stream, which formed from the confluence of the other two streams. The extent of metal enrichment was greater in the <0.0625-mm size sediments. A decreasing trend of metal concentrations in a downstream direction was not present in the enriched sediments. This was true for each metal in both size sediment fractions.  相似文献   

13.
Containment landfills: the myth of sustainability   总被引：5，自引：0，他引：5  
A. Allen   《Engineering Geology》2001,60(1-4):3-19
A number of major problems associated with the containment approach to landfill management are highlighted. The fundamental flaw in the strategy is that dry entombment of waste inhibits its degradation, so prolonging the activity of the waste and delaying, possibly for several decades, its stabilisation to an inert state. This, coupled with uncertainties as to the long-term durability of synthetic lining systems, increases the potential, for liner failure at some stage in the future whilst the waste is still active, leading to groundwater pollution by landfill leachate. Clay liners also pose problems as the smectite components of bentonite liners are subject to chemical interaction with landfill leachate, leading to a reduction in their swelling capacity and increase in hydraulic conductivity. Thus, their ability to perform a containment role diminishes with time. More critically, if diffusion rather than advection is the dominant contaminant migration mechanism, then no liner will be completely impermeable to pollutants and the containment strategy becomes untenable.

There are other less obvious problems with the containment strategy. One is the tendency to place total reliance on artificial lining systems and pay little attention to local geological/hydrogeological conditions during selection of landfill sites. Based on the attitude that any site can be engineered for landfilling and that complete protection of groundwater can be effected by lining systems, negative geological characteristics of sites are being ignored. Furthermore, excessive costs in construction and operation of containment landfills necessitate that they are large scale operations (superdumps), with associated transfer facilities and transport costs, all of which add to overall waste management costs. Taken together with unpredictable post-closure maintenance and monitoring costs, possibly over several decades, the economics of the containment strategy becomes unsustainable. Such a high-cost, high-technology approach to landfill leachate management is generally beyond the financial and technological resources of the less wealthy nations, and places severe burdens on their economies. For instance, in third world countries with limited water resources, the need to preserve groundwater quality is paramount, so expensive containment strategies are adopted in the belief that they offer greatest protection to groundwater. A final indictment of the containment strategy is that in delaying degradation of waste, the present generations waste problems will be left for future generations to deal with.

More cost-effective landfill management strategies take advantage of the natural hydrogeological characteristics and attenuation properties of the subsurface. The ‘dilute and disperse’ strategy employs the natural sorption and ion exchange properties of clay minerals, and it has been shown that in appropriate situations it is effective in attenuating landfill leachate and preventing pollution of water resources. Operated at sites with thick clay overburden sequences, using a permeable cap to maximise rainfall infiltration and a leachate collection system to control leachate migration, ‘dilute and disperse’ is a viable leachate management strategy. Hydraulic traps are relatively common hydrogeological situations where groundwater flow is towards the landfill, so effectively suppressing outwards advective flow of leachate. This approach is also best employed with a clay liner, taking advantage of the attenuation properties of clays to combat diffusive flow of contaminants. These strategies are likely to guarantee greater protection of groundwater in the long term.  相似文献   


14.
This study draws attention to the fact that natural processes can mobilize thallium （Tl）, a highly toxic metal, which may enter the food chain with severe health impacts on the local human population. A rural area having independent Tl mineralization in southwestern Guizhou, China, was chosen for a pilot study. Tl contents of soils extracted by HNO3 in the study area range from 35-165 mg/kg in soils from the mining area, 14-78 mg/kg in alluvial deposits downstream, and 〈0.2-0.5 mg/kg in soils from the background area. Tl contents in ammonium acetate EDTA-extracted fraction are 0.013-1.3 mg/kg, less than 1% of concentration in HNO3-extracted fraction. The amounts of Tl in NH4Ac-extracted fraction were thought to be more exchangeable and bioavailable, i.e., immediately available to plants and/or available to plant roots over a period of years. Tl concentration in crops exhibits species-dependent preferences. The enrichment of Tl in edible crop species decreases in the following order： green cabbage〉chili〉Chinese cabbage〉rice〉com. The highest level of Tl in green cabbage is up to 500 mg/kg （DW）, surpassing the values of Tl in the soils （13-59 mg/kg）. The enrichment factor for TI in green cabbage is up to 1-10 when considering the HNO3-extracted Tl, but the factor highly rises to 30-1300 while considering the NH4Ac-extracted Tl. The average daily uptake of Tl by the local villagers through consumption of locally planted crops was estimated at about 1.9 mg per person, which is 50 times the daily ingestion from the Tl-free background area.  相似文献   

15.
The current practice of slope stability analysis for a municipal solid waste (MSW) landfill usually overlooks the dependence of waste properties on the fill age or embedment depth. Changes in shear strength of MSW as a function of fill age were investigated by performing field and laboratory studies on the Suzhou landfill in China. The field study included sampling from five boreholes advanced to the bottom of the landfill, cone penetration tests and monitoring of pore fluid pressures. Twenty-six borehole samples representative of different fill ages (0 to 13 years) were used to perform drained triaxial compression tests. The field and laboratory study showed that the waste body in the landfill can be sub-divided into several strata corresponding to different ranges of fill age. Each of the waste strata has individual composition and shear strength characteristics. The triaxial test results showed that the MSW samples exhibited a strain-hardening and contractive behavior. As the fill age of the waste increased from 1.7 years to 11 years, the cohesion mobilized at a strain level of 10% was found to decrease from 23.3 kPa to 0 kPa, and the mobilized friction angle at the same strain level increasing from 9.9° to 26°. For a confinement stress level greater than 50 kPa, the shear strength of the recently-placed MSW seemed to be lower than that of the older MSW. This behavior was consistent with the cone penetration test results. The field measurement of pore pressures revealed a perched leachate mound above an intermediate cover of soils and a substantial leachate mound near the bottom of the landfill. The measurements of shear strength properties and pore pressures were utilized to assess the slope stability of the Suzhou landfill.  相似文献   

16.
This paper extends a previously developed three-part wedge method for the seismic stability analysis of the landfill with a triangular berm using pseudo-static method, and moreover, the translation failure condition of the landfill along under bottom of the berm is only presented. In the seismic impact zone, it is necessary to consider the impact of the seismic force on the stability of the landfill. Generally, apart from the horizontal seismic force, the landfill is also subjected to both upward and downward vertical seismic forces. The downward vertical seismic force has a positive impact on the seismic stability of the landfill, while the upward vertical seismic force is just opposite. Therefore, simply ignoring vertical seismic force, the seismic stability of the landfill will be overestimated or underestimated in the seismic condition. Besides, the seismic yield coefficient is calculated by assuming FSV = 2FS and the ratio of vertical seismic coefficient to horizontal seismic coefficient is equal to 2/3.  相似文献   

17.
This paper argues that human vulnerability to flood hazards in urban slums in developing countries is greatly affected by the positioning and activities of their city governments. As a result, the paper explores the central role of city authorities in the production of flood vulnerability in selected informal settlements in Accra, Ghana. Using a case study research design, the study draws on multiple qualitative methods to gather evidence including: document review, focus group discussions, flood victims’ interviews, institutional consultation and field observation. The paper reveals two main positions of state and city authorities in Accra’s perennial floods: first, being present and complicit in informal urbanization through their involvement in the politics of land management in flood prone zones; and second, being absent through their inaction in informal growth in flood-risk areas. To each of these positions of the urban state, there are emerging responses from residents and other non-state actors operating within and outside these informal communities. The paper proposes a re-examination of the current structure and processes of urban governance, state-community engagements and urban citizenship in informal communities.  相似文献   

18.
The generation of massive volume of slimes from sand mining industry ascertains the need for effective waste treatment. The application of slimes in landfill barrier construction works has been identified as one of the processes that can be used to reduce their volume, enabling in this way the rehabilitation of dangerous sites. This article presents a modified triaxial cell specially built to investigate high water content soils and discusses the results obtained from the investigation of the hydraulic properties of two slimes. The results of laboratory filter cake tests show that the slimes have reasonably good sealing capacities due to the formation of a cake layer on other porous materials upon draining. A relatively low hydraulic conductivity (1.5–3 × 10−9 m/s) was achieved, once the cake layer was formed. This is close to the prescribed 1 × 10−9 m/s required by the local environmental governmental authority for a landfill hydraulic barrier material, indicating their potential suitability as landfill barrier.  相似文献   

19.
The influence of local hydrogeology on natural attenuation of contaminants from landfill leachates in shallow aquifer underlying the active Olusosun landfill base in Lagos was investigated. In addition, the level of groundwater contamination in the vicinity of the landfill and of leachate migration pattern in groundwater down gradient of the landfill base was equally assessed. Landfill leachate and groundwater samples were collected and analyzed and characterized. Physico-chemical analyses of sampled water followed standard analytical methods. Analytical results showed a measurable impact of leachate outflows on groundwater quality. Elevated levels of anions: nitrate, chloride and sulphate in the groundwater body and heavy metals: Cr3. Cd and Cu, were detected at measurable levels in groundwater down gradient of the landfill location without any particular attenuation pattern. The migration pattern and dispersion of leachates down gradient, 750 m away from the landfill location are irregular and difficult to predict as depicted by levels of contaminants present in groundwater. The study highlighted the importance of soil stratigraphy beneath the landfill base as an important factor in the natural attenuation of leachate constituents in the groundwater body.  相似文献   

20.
This rebuttal was written in response to the rebuttal of the paper “choosing a municipal landfill site by analytic network process” published in 2007 by M. Sagir. This study was conducted as an application for the landfill site selection in the environmental engineering discipline. Since ANP was only the “instrument” used in our study, the details of this existing methodology were referenced, and not presented, due to page limitations and to match the content of the journal. Responses to M. Sagir’s comments are discussed within the body of this rebuttal.  相似文献   

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