IRSPAS 2018
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Item Development of a digestion technique for the determination of selected heavy metals in soil and sediments(Research Symposium on Pure and Applied Sciences, 2018 Faculty of Science, University of Kelaniya, Sri Lanka, 2018) Wekasinghe, K.; Subramanium, S. S.The objective of this study was to develop a new method on soil digestion techniques because some metal ions such as Cd, Pb, Cu, Cr and Zn are chelated by many soil-organic matter and complexes are inaccessible using previously studied techniques. This method development as well as the analysis of total contents of Cd, Pb, Cr, Cu and Zn in soil and sediment were conducted in selected areas in Medawachchiya, Sri Lanka which is an area that is mostly affected with Chronic Kidney Disease of unknown etiology. In this regard, the random soil samples were taken from cultivated and uncultivated paddy fields and the banks of the tanks. Sediments were collected randomly from the banks of the tanks. Three different digestion methods were used to analyze the heavy metals in soil to select the best digestion method for heavy metal analysis in soil for further studies. All three digestion methods have different combinations and quantities of concentrated acids (i.e., HNO3 and HCl) and H2O2. The heating methods were varied by using hot plate for one of the techniques (i.e., Gallenkamp) and microwave (i.e., Mars6 microwave digester) for the other two techniques. The digestion timing and temperature programming used are different in the three techniques. The results obtained using the Flame absorption spectrometer (i.e., GBC 2000, SavantAA) were analyzed. The results obtained for each technique were compared. Method spike recovery was conducted for the three methods to compare the difference, accuracy and effectiveness of each digestion processes. The concentration variation of heavy metals were as follows; Cd 1.0 mg/kg - 2.0 mg/kg, Cr 20 mg/kg - 60 mg/kg, Pb 10 mg/kg - 24 mg/kg, Zn 20 mg/kg - 110 mg/kg and Cu had the highest variation 20 mg/kg -170 mg/kg. Variation of the above values occur due to the variation of sample areas and environmental factors surrounding them. Further, the spiked method recovery for Zn suggests that the microwavebased digestion is more suitable for the analysis in soil. Results showed that the concentrations of Cu, Cr, Pb and Zn in soil were recorded within the permissible limits set by WHO. The Method LOD and LOQ suggests that the values obtained for Cd were not on the detectable limits and the use of GFAAS or any other sensitive analytical instrument is required for the analysis.Item 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 Heavy metal analysis of selected fruits and vegetables grown in CKDu prevalent Medawachchiya area in Sri Lanka(Research Symposium on Pure and Applied Sciences, 2018 Faculty of Science, University of Kelaniya, Sri Lanka, 2018) Hiruni, H. K.; Weerasooriya, M. K. B.In Sri Lanka, CKDu has become a major health issue over the past two decades. The disease is proved to be endemic. The number of environmental risk factors has been recognized globally as other probable causes of CKDu, such as exposure to heavy metals (cadmium, lead, mercury, and chromium), agrochemicals, and nephrotoxic substances. Hence, the current study was aimed to investigate whether there is any relationship between CKDu and heavy metal contaminants of selected fruits and vegetables grown in the effected area. Fruits of Mangifera indica (Mango), and Carica papaya (Papaw), leaves of Centella asiatica Gotukola), Talinum fruticosum (Gas nivithi), Amaranthus cruentus (Thampala) and fruit of Solanum torvum (Thibbattu) were selected for the study. Study was based on 15 sites of each Gramasevaka Niladhari (GN) area (Puhudiwula, Mahadiwulwewa, Unagaswewa) in Medawachchiya. Information of the about CKDu patients and above fruits and leafy vegetables (n=45) grown in their home gardens were collected during the Maha season. The content of Copper (Cu), Chromium (Cr), Cadmium (Cd) and Lead (Pb) in samples were analyzed using Flame atomic absorption spectroscopy. The results showed that leafy and fruity vegetables (Thibbattu) contain higher concentrations of heavy metals than fruits. The concentrations of Cu, Cr, Cd and Pb detected in the vegetable and fruit samples were ranged from 3.64 ± 0.07 to 23.60 ± 0.14 mg/kg, 0.60 ± 0.09 to 17.11 ± 0.16 mg/kg, 0.08 ± 0.03 to 0.88 ± 0.00 mg/kg and 0.18 ± 0.08 to 7.70 ± 1.48 mg/kg (dry weight basis) respectively. None of the fruits and vegetables tested in three study areas exceeded WHO safe limit for Cu, 40 mg/kg. All the Mango and papaya samples tested below safe limit of 4 tested metals. Regarding the leafy and fruity vegetables all the samples at Mahadivulwewa, nearly 95% samples at Puhudivula and 70% at Ungaswewa exceed the safe limit for Cd. Nearly 20% of leafy vegetables at Mahadiwulwewa,10% at Ungaswewa and Puhudivula exceed the safe limit for Pb whereas nearly 80% of leafy vegetables at three tested areas exceed the safe limit for Cr. Of the 15 sites selected, 13 patients at Mahadivulwewa, 07 and 05 patients at Puhudivula and Ungaswewa were recorded respectively. Heavy contamination of Cd recorded in the leafy and fruity vegetables in the home gardens of Mahadivulwewa could be one of the risk factor accounts for higher number of CKDu patients. Cd accumulation in renal cortex reported to cause renal damage decreasing Glomeular Filtration rate. However, further analysis is required to establish this fairly conclusively.