Browsing by Author "De Silva, R. C. L."

Now showing 1 - 10 of 10

Analysis of selected, commercially available inorganic fertilizers and soil NPK content in Puhudivula; Medawachchiya
(Research Symposium on Pure and Applied Sciences, 2018 Faculty of Science, University of Kelaniya, Sri Lanka, 2018) Sahlah, M. A. H. F.; De Silva, R. C. L.
The increased prevalence of CKDu confined to specific geographical regions and among specific occupational groups of Sri Lanka has drawn the attention of scientific community in recent years. This study was conducted to investigate possible contributions of inorganic fertilizer usage on the disease prevalence at Puhudivula; Medawachchiya. Five commercially available fertilizer samples (Urea, TSP, MOP, TOP and Chili mix) most commonly used in the study area were analyzed for their NPK content and trace metal amounts. The NPK composition, calcium content and physiological properties of soil were also analyzed in five selected sites. The total nitrogen amounts were determined using standard Kjeldahl procedure. Total phosphate content of fertilizers was analyzed using ammonium vanadomolybdate method while both total phosphate and inorganic phosphate amounts in soil were determined using molybdenum blue method. The potassium and calcium amounts were determined using flame photometry. The percentage NPK compositions of the analyzed fertilizer samples agree with the percentage compositions listed by the manufacturers for each fertilizer. However, less total nitrogen and less phosphate percentages were measured in Urea and TSP respectively. The NPK composition of soil followed N% > K% > P% order with overall mean concentration of NPK between 279.4-1537.3 mg/kg, 32.4-193.7 mg/kg and 3.0-25.5 mg/kg respectively. The mean calcium concentration in soil was high, ranged from 537.27-1007.75 mg/kg. The trace metals Cd, Pb, Cr, Zn, Cu and Fe in fertilizer samples were analyzed using Atomic Absorption Spectrometer. From the analyzed trace metals, Fe exhibited a remarkable presence in all analyzed fertilizers except Urea with an overall mean concentration >1550.0 mg/kg and the mean concentrations of Cd, Pb and Cr followed the phosphate percentage by weight. Cd and Pb mean concentrations ranged from 0.23-1.80 mg/kg and 0.94-7.17 mg/kg respectively and were below the WHO maximum acceptable concentrations. According to the results, the addition of fertilizers did not increase the heavy metal levels in soil significantly unless it accumulates, and the excessive use of inorganic fertilizers mainly the ammonium-based fertilizers in already nitrogen enriched soils indicates to be causing the acidification of soils and it is evident that it may be mobilizing the calcium ions from its immobile form. This study provides new data to relevant authorities to limit the excessive annual fertilizer input on these lands through proper NPK analysis prior to application.
Degradation of selected pesticides in soil in selected areas in Medawachchiya and HPLC analysis of pesticides
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Dassanayake, D. S.; De Silva, R. C. L.
It is known that diabetes, hypertension and different forms of glomerular nephritis are known etiologies of Chronic Kidney Disease (CKD). However, over the last two decades, a new strain of CKD known as Chronic Kidney Disease of unknown etiology (CKDu) has been endemic around the rural agricultural communities of the North Central Province of Sri Lanka. It is not related to a known cause commonly identified with CKD. Agrochemicals used is believed to be a cause of CKDu. Analysis of pesticide is often difficult due to interference and decomposition. Previous studies have noted that there were suspected peaks for ‘Diazinon’ and ‘Profenofos’ pesticides in the HPLC chromatograms of soil samples collected from Medawachchiya. Therefore, in order to test the presence of those pesticides in the ground, soil samples were collected and analyzed from selected cultivated areas of Medawachchiya were spiked with both Diazinon and Profenofos pesticides. Thirty representative soil samples (five samples per paddy field) were collected from six paddy fields from Karanbankulama Grama Niladhari division in Medawachchiya. Each soil sample was spiked with Profenofos (5.00 mg L-1) and Diazinon (5.00 mg L-1). Samples were digested using soxhlet extraction, from which the pesticide residues were extracted using solvent extraction. The extracts were analyzed through High Performance Liquid Chromatography (HPLC) analysis. Retention time of Diazinon at 5.89 minutes and that of Profenofos at 6.74 minutes and both peaks were detected throughout the study. When overlaid, the HPLC chromatograms of the non-spiked and spiked soil samples the same background peaks in non-spiked soil chromatogram were present in spiked soil chromatograms as well which resulted due to the common soil components retained in this soil. The results suggest presence of pesticide residue in the sample. The spiked pesticides are retained in soil samples throughout the study and the amount is decreased due to the degradation
Determination of heavy metals in soil in chronic kidney disease of unknown etiology affected areas of Karanbankulama (A preliminary study
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Rajaguru, R. A. M. T. S.; Subramanium, S.S.; De Silva, R. C. L.
The increased prevalence of Chronic Kidney Disease of unknown etiology (CKDu) among specific occupational groups confined to specific geographical regions of Sri Lanka has dragged the attention of scientific community in recent years. The objective of the study was to determine the concentrations of heavy metals Cu, Cr, Zn, Pb and Cd and characteristics like moisture content, organic matter content, pH and conductivity in soil samples obtained in the areas which are affected CKDu. The study was conducted in the Karanbankulama area in North Central Province, Sri Lanka. Soil samples were collected from reservoirs and paddy fields. Prior to the heavy metal analysis an acid or acid combination such as HCl: HNO3, HNO3: H2O2 and HNO3 was examined to digest the soil samples aid with microwave digestion. A higher metal concentration was obtained for aqua regia for each metal mentioned above when a selected soil sample was treated with the above acid combinations. Flame Atomic Absorption Spectrometer was used for the analysis of the samples. The resulted concentrations were 10-37, 20-86, 3-30 and 25-50 mg kg-1 for Cu, Pb, Cr and Zn respectively. However, Cd was not in detectable limits by FAAS. The results showed that the concentrations of Cr, Zn, Pb were in the permissible levels set by WHO (World Health Organization) while the concentration of Cu was recorded slightly above the permissible levels in paddy field soil of some sites. The soil characterization studies showed that the pH of the soil in tanks and paddy fields was in between 5-7. Moreover, the soil conductivity measurements showed a considerable variation even between the samples of the same site. This may be due to the variations in the accumulation of fertilizer in the paddy field. Furthermore, the concentration of the electrolytes was less than that of the paddy fields. The organic matter percentage of the soils in tanks in two sites were relatively higher than other sites. The moisture percentage in the tank soil samples was in the range 1-4% while it was 1-3% in the soil samples in the paddy fields
Extraction of Alumina from Kaolin found in Gem Mining Sites of Sri Lanka
(2024) Karunarathna, Y. D. T. I.; De Silva, R. C. L.
Purpose: The research focused on the insurance industry performance of India, Pakistan & Sri Lanka were supposed to find the impact of product diversification and Insurance activity towards industry performance measured by ROE. Further insurance penetration is considered a moderating variable and objectives same as mentioned above. Product diversification and Insurance activity are key indicators of the insurance industry and insurance penetration is a key indicator of country performance measurement. Methodology: This quantitative study considered countries of Sri Lanka, India, and Pakistan in the South Asian Region and considered the period data from 2012 -2022. The highest developed first three countries were considered for evaluation purposes and diversified (companies operating in both Life & General) insurance companies from each country. Findings: Both product diversification and insurance activity exhibit negative correlations with insurance industry performance, indicating that increasing either factor may result in lower financial performance for insurers in these countries. Furthermore, insurance penetration significantly moderates the relationship between product diversification and insurance industry performance. The three hypotheses formulated and stated that impact is negative for product diversification and insurance activity. Further stated that insurance penetration moderated the insurance industry's performance. Conclusion: The findings underscore the importance of prudent strategic planning and management for diversified insurance companies in India, Pakistan & Sri Lanka. Diversified insurance firms are advised to carefully weigh the trade-offs between diversification and profitability. While diversification can mitigate risk, it may also lead to diminishing the returns in long run.
Identification of Major Interfering Substances for Heavy Metal Determination in Northern Sea Areas of Sri Lanka
(2024) Anoja, N.; De Silva, R. C. L.; Prabagar, J.
This study investigated the physicochemical characteristics of seawater from five locations along the northern Sri Lankan coast, encompassing areas with varying degrees of anthropogenic activity. The analysis revealed significant variations in several parameters, potentially influenced by human influences. The results reveal significant variations in several parameters. For instance, turbidity levels varied from 1.88 NTU in Thalaiyadi to 13.3 NTU in Pannai, with Pannai, Myliddy, and Kakkaithivu exceeding the recommended limit of 5 NTU. Total suspended solids (TSS) ranged from 3 mg/L in Thalaiyadi to 83 mg/L in Pannai, surpassing the recommended limit of 30 mg/L. Electrical conductivity (EC) ranged from 45,700 µS/cm in Nainathivu to 49,500 µS/cm in Pannai, exceeding the typical seawater range. Nitrate levels ranged from 10.4 mg/L in Thalaiyadi to 19.1 mg/L in Myliddy. Major cations such as calcium (361 mg/L to 417 mg/L), magnesium (1,222 mg/L to 1,327 mg/L), and sodium (10,140 mg/L to 10,530 mg/L) also showed significant differences across locations. These findings highlight the need for continuous monitoring and effective management strategies to mitigate the negative impacts of anthropogenic activities on these coastal ecosystems. Furthermore, the complex seawater matrix presents challenges for heavy metal determination using Graphite Furnace Atomic Absorption Spectroscopy (GFAAS) due to spectral interferences from major cations, non-specific matrix effects, and interferences from organic matter, turbidity, and suspended solids. Careful consideration of these factors through background correction techniques, matrix modifiers, sample pre-treatment, and optimization of analysis parameters is crucial for accurate heavy metal determination in these environments. This study contributes to a better understanding of the environmental conditions and emphasizes the need for further research on heavy metal contamination and the development of robust analytical methods tailored to address the challenges posed by the complex seawater matrix in northern Sri Lanka.
Improving shelf life of commercial borate-glycol based wood preservatives
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Nandasiri, H. I. S. I.; De Silva, R. C. L.
Borates as wood preservatives have played an ever increasing role in preservation of wood against wood destroying insects and made them particularly attractive in today’s environmentally conscious market. But the precipitation of borates on storage in borate-glycol wood preservatives has largely limited their demand in the current wood preservative market. The main objective of this study was focused on the possibility of reducing the borate precipitation in order to expand the shelf life of these wood preservatives. A number of strategies were employed to lessen the precipitation of borates such as changing the solvent, boron concentration and boric acid to borax ratio. Different wood preservative formulations were prepared using monoethylene glycol (MEG) and monopropylene glycol (MPG) with varying boron percentages (10% -20%) and boric acid to borax ratio. Boron percentage in each formulation was determined by the titration method over six weeks and FT-IR-ATR analyses were carried out to confirm the composition of precipitate formed. Effectiveness of each formulation was measured by chemical retention, chemical penetration and laboratory no-choice feeding test using dry-wood termites. Mortality rate and wood weight loss of the test blocks were observed in termite no-choice feeding test. Wood preservatives made by MPG showed an earlier precipitation than MEG and wood preservatives having 20% boron precipitated earlier than that of the ones having 15% and 10% boron. This indicates that both type of solvent and boron concentration have a direct influence for the precipitation of borates in wood preservative. There was a remarkable difference between penetration and retention of wood preservatives made by different solvents and boron concentration. Highest penetration and retention were observed in the formulation containing 20% B in MPG. According to the termite no-choice feeding test, all the formulations showed 100% mortality when applied them in 1:1 (by volume) aqueous dilution of borate/glycol. Termite mortality increased from about 83% to 100% with increasing boron percentage 15% to 20% when applied 1:2 aqueous dilution of borate/glycol. According to the results obtained, 15% B in MEG with 1:1.50 boric acid to borax ratio is the suitable formulation for borate-glycol wood preservative owing to its high effectiveness to wood destroying insects, long shelf life and cost effectiveness
Mapping of well water and soil parameters in a selected Grama Niladhari division of Gampaha district
(Faculty of Science, University of Kelaniya Sri Lanka, 2022) Pathirana, H. P. K. V. T.; De Silva, R. C. L.
This study intends to fill an essential knowledge gap in the field of environmental information in Sri Lanka, by providing a reliable data bank supporting the information of existing chemical species of two important components, well water and soil. Further, this study would provide reference information for future work and aid in explaining the changes that would occur due to the changes in chemical composition of the environment. Thalawathuhenpita North Grama Niladhari division was selected as the initial site of study and sampling was done from 23 locations, where two representative samples of each soil and well water were collected from each site. All chemicals, instruments and glassware used were from recognized chemical supply companies. This study investigates several important well water quality parameters such as pH determined by a pH meter, well water hardness and Calcium content using complexometric titrations, nitrate content using a spectrometric analysis, Iron content using a colorimetric analysis, and soil quality parameters such as active pH using a pH meter, water-soluble and exchangeable cations (Na+, K+) using a flame photometer and water-soluble and exchangeable Ca2+ using complexometric titration, organic matter content using a redox titration, iron content and nitrate content were determined similar to well water analysis. The readings were duplicated and reported as means ± standard deviation, and contour maps were produced using Surfer ® (Golden Software, LLC). Maps depict the scope of variation of the determined parameters within the selected area and highlight that it is crucial to monitor the environmental resources chemically in a regular manner to address the environmental problems that may occur in the future. The mapping of the entire country on a fixed and frequent basis will give environmentalists, scientists and policymakers information about a given environment and thus make monitoring and policy making of an area easy.
Method development for the investigation of pesticide residues in soil and heavy metal contamination in pesticides in selected Chronic Kidney Disease of unknown etiology (CKDu) affected areas in Medawachchiya
(Research Symposium on Pure and Applied Sciences, 2018 Faculty of Science, University of Kelaniya, Sri Lanka, 2018) Mohotti, N. De. S.; De Silva, R. C. L.
Chronic Kidney Disease of unknown etiology (CKDu) has become one of the major public health problems in the North Central Province in Sri Lanka. There is a major concern that the agrochemicals could contribute to CKDu because North Central Province is an agricultural area where agrochemicals have been used for a prolonged period of time. Pesticides could affect the environment either by remaining in the environment as their residues or as a source of heavy metals in the environment. The purpose of this research is to optimize a method for the qualitative analysis of pesticide residues in soil. Puhudivula grama niladhari division which is an area with a high recorded number of CKDu patients in Medawachchiya was selected as the sampling area. Five representative soil samples each from six paddy fields were collected for the study. This study includes qualitative soil analysis of selected pesticide residues such as Profenofos, Diazinon and Imidacloprid, which are the most commonly used paddy field pesticides in Medawachchiya. The presence of these pesticide residues in agricultural soil were analyzed by a Soxhlet extraction method followed by High-Performance Liquid Chromatography (HPLC) and method optimization was carried out according to the matrix. Pesticide residues were absent or below the detection limits. Further studies are required to minimize the background interference from matrix and LC- MS studies are required for the quantification of the residues. The study also includes quantification of heavy metals such as Pb, Cd, Cr and Cu in pesticides by the flame atomic absorption spectroscopy (FAAS). Both commercially available solid pesticides such as Nativo, Mancozeb and liquid pesticides such as Greenup, Profenofos obtained from Medawachchiya area were used for this analysis. When it comes to solid pesticides, Mancozeb showed the highest Pb, Cd, Cr and Cu concentrations as 5.163 ± 0.283 mg/kg, 7.329 ± 0.038 mg/kg, 2.963 ± 0.207 mg/kg, 4.246 ± 1.706 mg/kg respectively. The method recovery values of the quantification of heavy metals in solid pesticides were above 70.00%. From liquid pesticides, Profenofos showed the highest Pb, Cd, Cr and Cu concentrations as 1.533 ± 0.160 mg/L, 1.357 ± 0.040 mg/L, 6.909 ± 0.657 mg/L, 4.905 ± 0.465 mg/L respectively and the method recovery values for the quantification of heavy metals in liquid pesticides were very low with values below 50.00%. Limit of detection and limit of quantification studies proved that all the values were within the detectable limits.
Removal of color pigments from recycling plastics
(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Sathruwani, J. A.; De Silva, R. C. L.
The presence of additives in plastics poses a significant environmental threat and complicates plastic recycling. These additives hinder effective recycling, leading to recycled products being mostly used in lower-quality applications. Colorants in plastics worsen this issue, causing the final recycled product to have a grey color. As a workaround, it has become common to add dark colored additives to recycled plastics to preserve aesthetics. However, this limits the versatility and widespread use of recycled plastics. The complex interaction of colorants in plastics highlights the urgent need for advanced solutions in plastic recycling. In this study, the treatment of plastic waste to extract colorant using organic solvent was investigated. The plastic wastes used were Polystyrene (PS), High Density Polyethylene (HDPE), and Polypropylene (PP). As the first step, acetic anhydride was selected as the colorant extraction solvent among the other organic solvents. It was used to extract colorant from PS plastic with orange, yellow, and pink colors. Three cycles of extraction were carried out for each of them. Then identified the type of colorant (pigment or dye) present in the PS pieces using microscope observations and found that all the three were pigments. Additional examination of these pigments using FTIR revealed their specific functional groups. The application of acetic anhydride was found to be ineffective in the extracting colorants from HDPE and PP. Furthermore, activated carbon was used to successfully remove pigments from extracts to encourage the reuse of solvents. Absorbance was measured at 300-700 nm range using UV-visible spectrophotometer verified that the solvent can be reused up to eight times without losing its effectiveness. The results highlight a notable reduction in pigment levels of PS resulting in 85–90% in yellow and pink pigments and 70–75% in orange pigment demonstrating the effectiveness of the proposed removal technique. Sustainable pretreatment helps reducing plastic waste and has economic benefits. This method can improve the quality of recovered polymers by shifting darker shades to lighter tone, highlighting the potential to create bright and visually appealing recycled items which produce revenue. Therefore, it provides a potential and economical approach to improving sustainable recycling methods for plastics.
Spatial distribution of soil and water quality in Eldeniya - East grama niladhari division
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Deraniyagala, P. E. P. S.; Heenkenda, H. M. D. S. D.; De Silva, R. C. L.
Water is becoming a consequential part of the daily life of humans. Therefore, mapping of soil and water quality parameters is required for regular monitoring of them to provide the necessary evidence to make decisions on managing water and soil quality today and in the future. Furthermore, mapping soil and water quality parameters is necessary for environmental monitoring, agricultural management, land use planning, water resource management, and conservation efforts. This research analyzes soil and water quality parameters in the EldeniyaEast grama niladhari division, Gampaha district. Fifty-six samples of soil and water were collected from the selected area. Water quality parameters pH, conductivity, nitrate content, phosphate content, and hardness were analyzed, and soil quality parameters pH, nitrate content, soil organic matter content, Na+, K+, and Ca2+ content in the soil were analyzed. Then their spatial distribution was represented as contour maps. pH was analyzed using a pH meter and the pH of water samples lies between 3.79 – 7.18. Except for one, all the other water samples gave acidic pH. Suggesting that Eldeniya-East has almost all acidic water sources. The conductivity of water samples was measured using a conductivity meter and the obtained values lie between 54.0 µS/cm – 403.0 µS/cm. All the samples gave extremely low conductivity values. Water-soluble phosphate was not detected in the water samples. This suggests that water sources within this area are not contaminated with excessive amounts of phosphates. Nitrate content was measured using an ionselective nitrate electrode and the obtained values lie between 59.5 ppm to 168.0 ppm. According to EPA, this area's water sources have nitrate contents higher than the safe levels for drinking water. The calcium hardness of water samples lies between 0.00 – 59.92 mg CaCO3/L, and Mg2+ was not detected. According to Sawyer and McCart's classification, all water samples are categorized as soft water. The pH of the soil samples lies between 3.07 – 6.68 where all are acidic pH values. Considering obtained soil and water pH values, it can be said that the study area has a considerable acidic nature. Nitrate content in soil samples lies between 52.2 – 217.0 ppm and a linear relationship exists between soil nitrate content and the water nitrate content. SOM of soil samples was measured using the Walkley–black method, and SOM lies between 0.000 – 12.930 %. According to the results, this area contains water-soluble calcium in a range of 0 - 2 mg/L, water-soluble sodium in a range of 6 - 18 mg/L, extractable sodium in a range of 1 - 56 mg/L, water-soluble potassium in a range of 1 - 12 mg/L and extractable potassium in a range of 9 – 108 mg/L. This analysis, which has been conducted as a pilot project covering only one grama niladari division can be further extended to map the entire country which then can be used for the continuous investigation of soil and water quality parameters.