ARS - 2005
Permanent URI for this collectionhttp://repository.kln.ac.lk/handle/123456789/162
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Item A kinetic study on slow natural degradation of polycyclic aromatic hydrocarbons in Bolgoda Lake waters and a technique for rapid destruction of them in the aquatic environment(Proceedings of the Annual Research Symposium 2005-Faculty of Graduate Studies, University of Kelaniya, 2005) Pathiratne, K.A.S.; de Silva, O.C.P.Polycyclic aromatic hydrocarbons (PAHs) are unique environmental contaminants that exhibit strong toxic, carcinogenic and mutagenic properties. They are generated through incomplete combustion of organic matter such as fossil fuels (petrol, diesel, and natural gasses, etc.), wood and many other organic compounds used in variety of industrial and domestic processes. Once formed, they are adsorbed on to particulate matter and deposited on ground and in water bodies through continuous atmospheric fallouts. During rainy seasons, PAHs deposited on ground surfaces are washed into water bodies through surface runoff. A recent study revealed that water and sediment in Bolgoda lake to contain PAHs above safe levels. Further, the levels observed during dry seasons were found to increase after heavy rains, followed by gradual degradation during dry periods. As a part of the present investigation, the kinetics of degradations of four selected PAHs; naphthalene, phenanthrene, pyrene and chrysene (2, 3, 4 and 5 member ring compounds) found in Bolgoda lake were carried out. Four different environmental matrices given below (a) to (d): (a) Bolgoda lake water exposed continuously to incandescent radiation of a 60 W tungsten lamp at room temperature. (b) Bolgoda lake water kept in dark at room temperature. (c) Deionized water with pH and electrical conductivity (EC) adjusted to those of Bolgoda lake water, exposed continuously to incandescent radiation of 60 W tungsten lamp at room temperature (d). Deionized water with pH and EC adjusted to those of Bolgoda lake water, kept in dark at room temperature. These four different media could represent unique environmental components found in Bolgoda lake that could be responsible for degradations of PAHS in the Bolgoda lake. The results indicate that pseudo first order rate constants corresponding to degradations of all four PAHs in the four different media at room temperature decrease in the order a > b > c > d. Also, in all four media the order of the pseudo first order rate constants for degradations of the four PAHs found to vary as chrysene > naphthalene > pyrene > phenanthrene. As the other part of the investigation, the suitability of a modified Fenton based oxidation process to enhance the rate of degradation of PAHs in aquatic environment was investigated. The effect of initial concentration of H2 O2 & Fe2+ ions, pH of the solution and the presence of triton X-100, a surfactant which could bring non polar PAHs and polar Fenton reagents in close proximity to facilitate degradation reaction were examined for 3,4 and 5 member ring compounds: phenanthrene, pyrene and benzo(a)pyrene found in local aquatic environments. Pseudo first order rate constants for degradations of all three PAHs found to increase with increasing initial H2 O2 concentrations and initial Fe2+ concentration in aqueous media. High degradation rates were observed for concentration ratios, [H2 O2 ]:[Fe2+] in the range of ~50 to ~100. Decrease of pH of solutions, also increased the rates of degradation of all three PAHs. Presence of Triton X-100 at low levels, (1% v/v in the solution) found to increase the degradation rates of all three PAHs. Under all conditions studied, the pseudo first order rate constants for degradation of Benzo(a)pyrene were found to be the largest among the three PAHs .Item Induction of pollutant responsive biomarkers, ethoxyresorufin–Odeethylase, glutathione S-transferase and biliary fluorescent aromatic compounds in tilapia inhabiting Bolgoda North Lake, Sri Lanka.(Proceedings of the Annual Research Symposium 2005-Faculty of Graduate Studies, University of Kelaniya, 2005) Chandrasekera, L.W.H.U.; Pathiratne, A.; Pathiratne, K.A.S.The presence of organic contaminants in aquatic systems poses a serious threat to environmental health. Biomarkers are sub-lethal biological measures of the response to and effect of pollutants in living organisms. Use of biomarkers has been identified as a powerful and cost-effective approach to obtain information on the state of the environment and the effect of pollutants on living biological resources. This study presents results of a part of the research project which focuses on evaluation of the use of biomarkers in food fish tilapia as tools in monitoring pollution in inland waterbodies in Sri Lanka. In the present study, activities of two enzyme biomarkers, ethoxyresorufin-O-deethylase (EROD) & glutathione S-transferase (GST) and biliary fluorescent aromatic compounds (FACs) in Nile tilapia (Oreochromis niloticus) collected from Bolgoda North Lake were evaluated in comparison to the baseline levels of the control fish in order to assess the biomarker responses in this fish. The results revealed that EROD and GST activities of tilapia inhabiting Bolgoda North Lake were significantly elevated several folds in comparison to the baseline levels. Liver somatic index and microsomal and cytosolic protein levels in the gill and liver tissues of fish collected from the lake were also elevated significantly compared to the controls. Induction of EROD and GST enzymes indicate the exposure of fish residing in the lake to organic contaminants such as polycyclic aromatic hydrocarbons (PAH) and polychlorinated biphenyls (PCB). Analysis of biliary FACs in the fish showed recent uptake of naphthalene, pyrene and benzo(a)pyrene type PAHs. Occurrence of PAHs in the colloids and sediments of Bolgoda North Lake has been confirmed by chemical analysis. Results suggest that EROD and GST in liver and gill tissues and FACs in bile in this fish are promising biomarkers of organic contaminations especially PAHs in the aquatic environments.Item The effects of application of three different phosphate fertilizer sources on the short term availability of some phosphorus fractions in the lateritic soils of intermediate zone of Sri Lanka(Proceedings of the Annual Research Symposium 2005-Faculty of Graduate Studies, University of Kelaniya, 2005) Duminda, D.M.S.; Pathiratne, K.A.S.; Somasiri, L.L.W.The present study investigates, the application of three phosphorous (P) fertilizer sources; Imported Rock Phosphate (IRP), Eppawela Rock Phosphate (ERP) and Triple Super Phosphate (TSP) on the short term availability of different P fractions in the lateritic soils in the intermediate zone of Sri Lanka. The available different P fractions in pots with and without Ruzi grass (Brachiaria ruziziensis L.) as an indicator plant was determined after six months from the date of application of the fertilizers. Each P fertilizer, was treated in triplicate at three different levels, viz., 15, 30, 60 mg P2 O5 /100g soil, separately into pots with and without Ruzi grass. The control with and without Ruzi grass was also carried out in triplicate without fertilizers. The soil moisture content in all the pots was maintained at 60% of field capacity. Phosphorus concentration and total dry matter content of grass were determined bimonthly over six month period. The soils were analyzed for the concentrations of different P fractions, viz., saloid bound P (Sa–P), aluminium bound P (Al–P), iron bound P (Fe– P), occluded P (Occ–P) and calcium bound P (Ca–P). The results revealed that, (i) Ruzi grass utilize more Sa-P and Al-P fractions than Occ-P, Fe-P and Ca-P fractions. (ii) The P uptake by Ruzi grass was low for both IRP and ERP applications compared to TSP application. (iii) Both ERP and IRP fertilizers did not show any significant increase in P uptake with increasing level of their application. Unlike ERP and IRP, the TSP applications showed a linear increase of P uptake by Ruzi grass with increasing the level of P treatment. The overall results indicated that, for short term application TSP is superior to IRP and ERP, though IRP was found to be slightly better than ERP in providing available P.Item Effect of application of three phosphate fertilizer sources on long term availability of different phosphorus fractions in lateritic soils in the intermediate zone of sri lanka(Proceedings of the Annual Research Symposium 2005-Faculty of Graduate Studies, University of Kelaniya, 2005) Duminda, D.M.S.; Pathiratne, K.A.S.; Somasiri, L.L.W.The application of three different phosphorous (P) fertilizer sources, viz., Eppawela rock phosphate (ERP), Imported rock phosphate (IRP) and Triple super phosphate (TSP) on the long term availability of several different P fractions in Lateritic soils in the intermediate zone of Sri Lanka was investigated. Each P fertilizer was treated at three different levels: 25, 50 and 100 g / palm/ 6 months in triplicate over a period of 11 years to all 6 coconut trees grown in each of the 30 experimental plots. Three experimental plots with 6 coconut trees in each with no fertilizer application were used as controls. After 11 years of fertilizer applications, soils were sampled 90 cm away from the base of coconut palm at 2 depths; (0-25) cm and (25-50) cm from randomly selected three plants from each of the plot. Soils of each treatment, sampled in triplicate, for each of the two depths were composited separately. Different P fractions, viz., saloid bound P ( Sa-P), aluminum bound P (Al-P), iron bound P (Fe-P), occluded P (Occ-P) and calcium bound P (Ca-P) were determined in each composited soil. The results showed that, in the soil depth of (0-25) cm, the ability of different fertilizers in producing plant available P; Sa-P and Al-P vary in the order of TSP>> IRP>ERP. Further, it was found that, the availability of Sa-P and Al-P in the TSP treated soil increased with increasing level of TSP application to the soil. The concentration of different P fractions in the TSP treated were in the order of Sa-P>Al-P>Occ-P>Fe-P>Ca-P. The increasing level of IRP and ERP applications did not increase the Sa-P and Al-P concentrations in the soil. The trend of the availability of different P fractions in the soil depth of (25-50 cm) was the same for all three of fertilizer sources at all three levels applications. However, the concentrations of soil P fractions found in this depth was smaller than the amounts found in the (0-25) cm depth.