International Research Symposium on Pure and Applied Sciences (IRSPAS)
Permanent URI for this communityhttp://repository.kln.ac.lk/handle/123456789/15650
Browse
5 results
Search Results
Item 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 fieldsItem 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 degradationItem 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 effectivenessItem 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.Item 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.