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1.
Relation of waste generation and composition to socio-economic factors: a case study 总被引:3,自引:0,他引:3
Bandara NJ Hettiaratchi JP Wirasinghe SC Pilapiiya S 《Environmental monitoring and assessment》2007,135(1-3):31-39
To develop an effective waste management strategy for a given region, it is important to know the amount of waste generated
and the composition of the waste stream. Past research has shown that the amount of waste generated is proportional to the
population and the average mean living standards or the average income of the people. In addition, other factors may affect
the amount and composition of waste. These are climate, living habits, level of education, religious and cultural beliefs,
and social and public attitudes. This paper presents the findings of a study carried out in a suburban municipal area in Sri
Lanka to determine the solid waste generation rate and waste composition based on field surveys and to determine the related
socio-economic factors. A database was developed that included information on the quantity and composition of waste generated
in a sample of households in the study area over a time period. The collected data was analysed to relate waste generation
and composition data to various socio-economic factors. Over 400 sample households were selected for the study using a stratified
random sampling methodology based on municipal wards and property values. A technique that considers both the number of households
in a particular income group (property value range) and the standard deviation of property values within a given income group
was used to determine the appropriate sample size for each municipal ward. Through category and regression analyses, the quantities
of waste and waste composition were related to several socio-economic factors. The paper describes the basis for the sample
selection, the methodology adopted for data collection, the socio-economic parameters used for the analysis, and the relationships
developed from the analysis. 相似文献
2.
Efficacy of woody biomass and biochar for alleviating heavy metal bioavailability in serpentine soil 总被引:1,自引:0,他引:1
Tharanga Bandara Indika Herath Prasanna Kumarathilaka Zeng-Yei Hseu Yong Sik Ok Meththika Vithanage 《Environmental geochemistry and health》2017,39(2):391-401
Crops grown in metal-rich serpentine soils are vulnerable to phytotoxicity. In this study, Gliricidia sepium (Jacq.) biomass and woody biochar were examined as amendments on heavy metal immobilization in a serpentine soil. Woody biochar was produced by slow pyrolysis of Gliricidia sepium (Jacq.) biomass at 300 and 500 °C. A pot experiment was conducted for 6 weeks with tomato (Lycopersicon esculentum L.) at biochar application rates of 0, 22, 55 and 110 t ha?1. The CaCl2 and sequential extractions were adopted to assess metal bioavailability and fractionation. Six weeks after germination, plants cultivated on the control could not survive, while all the plants were grown normally on the soils amended with biochars. The most effective treatment for metal immobilization was BC500-110 as indicated by the immobilization efficiencies for Ni, Mn and Cr that were 68, 92 and 42 %, respectively, compared to the control. Biochar produced at 500 °C and at high application rates immobilized heavy metals significantly. Improvements in plant growth in biochar-amended soil were related to decreasing in metal toxicity as a consequence of metal immobilization through strong sorption due to high surface area and functional groups. 相似文献
3.
Composite tin and zinc oxide nanocrystalline particles for enhanced charge separation in sensitized degradation of dyes 总被引:7,自引:0,他引:7
Composite ZnO/SnO2 catalyst has been studied for the sensitized degradation of dyes e.g. Eosin Y (2', 4', 5', 7'-tetrabromofluorescein disodium salt) in relation to efficient charge separation properties of the catalyst. Improved photocatalytic activity was observed in the case of ZnO/SnO2 composite catalyst compared to the catalytic activity of ZnO, SnO2 or TiO2 powder. The suppression of charge recombination in the composite ZnO/SnO2 catalyst led to higher catalytic activity for the degradation of Eosin Y. Degradation of Eosin follows concomitant formation of CO2 and formation of CO2 followed a pseudo-first-order rate. Photoelectrochemical cells constructed using SnO2, ZnO, ZnO/SnO2 sensitized with Eosin Y showed V(oc) of 175, 306, 512 mV/cm2 and I(sc) of 50, 70, 200 microA/cm2 respectively. A higher irreversible degradation of Eosin Y and higher V(oc) observed on composite ZnO/SnO2 than ZnO and SnO2 separately can be considered as a proof of enhanced charge separation of ZnO/SnO2 catalyst. Eosin Y showed a higher emission decreases on ZnO/SnO2 composite than on individual ZnO, SnO2 or TiO2 indicating dominance of the charge injection process. Photoinjected electrons are tunneled from ZnO to SnO2 particles accumulating injected electrons in the conduction bands allowing wider separation of excited carriers. 相似文献
4.
Bandara JM Wijewardena HV Bandara YM Jayasooriya RG Rajapaksha H 《Environmental geochemistry and health》2011,33(5):439-453
Chronic renal failure (CRF) associated with elevated dietary cadmium (Cd) among farming communities in the irrigated agricultural area under the River Mahaweli diversion scheme has reached a significantly higher level of 9,000 patients. Cadmium, derived from contaminated phosphate fertilizer, in irrigation water finds its way into reservoirs, and finally to food, causing chronic renal failure among consumers. Water samples of River Mahaweli and its tributaries in the upper catchment were analyzed to assess the total cadmium contamination of river water and the possible source of cadmium. Except a single tributary (Ulapane Stream, 3.9?μg?Cd/l), all other tested tributaries carried more than 5?μg?Cd/l, the maximum concentration level accepted to be safe in drinking water. Seven medium-sized streams carrying surface runoff from tea estates had 5.1-10?μg?Cd/l. Twenty larger tributaries (Oya), where the catchment is under vegetable and home garden cultivation, carried 10.1-15?μg?Cd/l. Nine other major tributaries had extremely high levels of Cd, reaching 20?μg?Cd/l. Using geographic information system (GIS), the area in the catchment of each tributary was studied. The specific cropping system in each watershed was determined. The total cadmium loading from each crop area was estimated using the rates and types of phosphate fertilizer used by the respective farmers and the amount of cadmium contained in each type of fertilizer used. Eppawala rock phosphate (ERP), which is mostly used in tea estates, caused least pollution. The amount of cadmium in tributaries had a significant positive correlation with the cadmium loading of the cropping system. Dimbula Tea Estate Stream had the lowest Cd loading (495.9?g/ha/year), compared with vegetable-growing areas in Uma Oya catchment with 50,852.5?g?Cd/ha/year. Kendall's τ rank correlation value of total Cd loading from the catchment by phosphate fertilizer used in all crops in the catchment to the Cd content in the tributaries was +0.48. This indicated a major contribution by the cropping system in the upper catchment area of River Mahaweli to the eventual Cd pollution of river water. Low soil pH (4.5-5.2), higher organic matter content (2-3%), and 18-20?cmol/kg cation exchange capacity (CEC) in upcountry soil have a cumulative effect in the easy release of Cd from soil with the heavy surface runoff in the upcountry wet zone. In view of the existing water conveyance system from upcountry to reservoirs in North Central Province (NCP) through diversion of River Mahaweli, in addition to their own nonpoint pollution by triple superphosphate fertilizer (TSP), this demands a change in overall upper catchment management to minimize Cd pollution through agriculture inputs to prevent CRF due to elevated dietary cadmium among NCP farmers. 相似文献
5.
Weerasooriya R. R. Liyanage L. P. K. Rathnappriya R. H. K. Bandara W. B. M. A. C. Perera T. A. N. T. Gunarathna M. H. J. P. Jayasinghe G. Y. 《Environment, Development and Sustainability》2021,23(9):12661-12709
Environment, Development and Sustainability - Application of advanced techniques to ensure the environment sustainability and freshwater ecosystem conservation is a paramount importance. Industrial... 相似文献
6.
Bandara JM Senevirathna DM Dasanayake DM Herath V Bandara JM Abeysekara T Rajapaksha KH 《Environmental geochemistry and health》2008,30(5):465-478
Chronic renal failure (CRF), in the main agricultural region under reservoir based cascade irrigation in Sri Lanka has reached crisis proportion. Over 5,000 patients in the region are under treatment for CRF. The objective of this study is to establish the etiology of the CRF. Concentrations of nine heavy metals were determined in sediments, soils of reservoir peripheries, water and Nelumbo nucifera (lotus) grown in five major reservoirs that supply irrigation water. All five reservoirs carried higher levels of dissolved cadmium (Cd), iron (Fe) and lead (Pb). Dissolved Cd in reservoir water ranged from 0.03 to 0.06 mg/l. Sediment Cd concentration was 1.78-2.45 mg/kg. No arsenic (As) was detected. Cd content in lotus rhizomes was 253.82 mg/kg. The Provisional Tolerable Weekly Intake (PTWI) of Cd based on extreme exposure of rice is 8.702-15.927 mug/kg body weight (BW) for different age groups, 5-50 years. The PTWI of Cd due to extreme exposure of fish is 6.773-12.469 mug/kg BW. The PTWI on a rice staple with fish is 15.475-28.396 mug/kg BW. The mean urinary cadmium (UCd) concentration in CRF patients of age group 40-60 years was 7.58 mug Cd/g creatinine and in asymptomatic persons UCd was 11.62 mug Cd/g creatinine, indicating a chronic exposure to Cd. The possible source of Cd in reservoir sediments and water is Cd-contaminated agrochemicals. The CRF prevalent in north central Sri Lanka is a result of chronic dietary intake of Cd, supported by high natural levels of fluoride in drinking water, coupled with neglecting of routine de-silting of reservoirs for the past 20 years. 相似文献
7.
Wasana Hewa M. S. Aluthpatabendi Dharshani Kularatne W. M. T. D. Wijekoon Pushpa Weerasooriya Rohan Bandara Jayasundera 《Environmental geochemistry and health》2016,38(1):157-168
Environmental Geochemistry and Health - High prevalence of chronic kidney disease of unknown etiology (CKDu) in some regions of the world is suspected mainly due to a toxin-mediated renal failure.... 相似文献
8.
A study was conducted on the island of Mahé, Seychelles, on five species of chironomous larvae endemic to the island. The chironomous larvae were exposed to four heavy metals – copper (Cu), cadmium (Cd), mercury (Hg), and zinc (Zn), for a 96-hr period, and the LC50 values were calculated. It was observed that the most sensitive species of chironomous larvae was Gymnometriocnemus mahensis. The least sensitive form of chironomous larvae examined was Paramerina minima. The 96-hr LC50 values obtained for Tanypus complanatus for Cu, Cd, Hg, and Zn were 1.9 (1.73–2.09), 1.35 (1.17–1.57), 0.33 (0.26–0.43), and 28.96 (27.03–31.03) ppm, respectively. Similar results were obtained for other species studied. 相似文献
9.
Macroscopic and vibration spectroscopic evidence for specific bonding of arsenate on gibbsite 总被引:1,自引:0,他引:1
The As(V) adsorption onto gibbsite under different experimental conditions was examined. Macroscopic data suggests strong As(V) bonding on gibbsite possibly via a bidendate binuclear complexation mechanism. The As(V) adsorption was quantified with the charge distribution multi-site ions complexation (CD-MUSIC) model distributing the anion charge over 0- and 1-planes according to the modified Pauling's bond valence theory. In the dual-adsorbates system of As(III) and As(V), the As(III) adsorption was predicted up to pH 8 utilizing the binding constants derived for single-adsorbate data. However, with pH > 8, the modeled As(III) adsorption data is overestimating the experimental values. 相似文献
10.
This paper explores the way in which the stated willingness to pay for the conservation of Asian elephants in Sri Lanka varies with hypothetical variations in their abundance. To do that, it relies on results from a sample of residents of Colombo. The willingness to pay function is found to be unusual. It increases at an increasing rate for hypothetical reductions in the elephant population compared to its current level (a level that makes the Asian elephant endangered) and also increases at a decreasing rate for increases in this population from its current level. Rational explanations are given for this relationship. The relationship is, however, at odds with relationships suggested in some of the literature for total economic value as a function of the abundance of a wildlife species. It is suggested that willingness to pay for conservation of a species rationally includes a strategic element and may not always measure the total economic value of a species. Nevertheless, willingness to pay is still policy relevant in such cases. 相似文献