IRSPAS 2019
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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 effectiveness