International Research Symposium on Pure and Applied Sciences (IRSPAS)

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Author: search.filters.author.Heshani, A.L.S.

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    Sensitivity of four freshwater animal species to copper and cadmium under tropical temperature exposure
    (Research Symposium on Pure and Applied Sciences, 2018 Faculty of Science, University of Kelaniya, Sri Lanka, 2018) Heshani, A.L.S.; Pathiratne, A.
    Copper and cadmium are two common pollutants in Sri Lankan freshwater ecosystems. Water quality criteria for these metals focusing on the protection of freshwater species in Sri Lanka are yet unavailable. Formulating water quality criteria based on tropical species sensitivity distribution analysis would require credible ecotoxicity data (especially at early life/young stages) under tropical temperature exposure for a range of freshwater species belonging to different trophic levels. Thus, objective of the present study was to generate freshwater ecotoxicity data for copper and cadmium for tropical temperature exposures using four freshwater native/model test organisms: two crustaceans, Daphnia magna and Moina macrocopa, the fish Poecilia reticulata and the tadpoles of Duttaphrynus melanostictus representing primary and secondary consumers. Based on the range finding tests, the animals were exposed separately to a series of concentrations of Cu2+ (D . magna 50-300; M . macrocopa 1-150; fish 25-300; tadpole 10-300) or Cd2+ (D . magna 10-200; M . macrocopa 1-150; fish 25-300; tadpole 100-500) in μg/L along with the controls (in triplicate/quadruplicate exposure medium, n=10 animals per replicate) at 280C - 300C under static-renewal conditions (hardness ≤ 66 mg/L as CaCO3) following standard OECD toxicity testing protocols. The sensitivity of the crustaceans (neonates) for different concentrations of Cu2+ and Cd2+ exposure was assessed based on percentage neonates immobilized whereas the sensitivity of P . reticulata (fry 5-10 mm total length) and D . melanostictus (Gosner stage 25 tadpoles) was evaluated based on percent mortality. Concentrations of copper and cadmium in the exposure media were determined using atomic absorption spectrophotometry. Ecotoxicity thresholds were estimated based on concentration-toxicity response relationships using USEPA software, ‘Toxicity Relationship Analysis Program’. Estimated 48 hour median effective concentration (EC50) of copper for immobilization of the crustaceans, D . magna and M . macrocopa were 117 and 15 μg/L respectively whereas corresponding values for cadmium were 45 and 12 μg/L. Estimated 96 hour median lethal concentration (LC50) values of copper for the fish, P . reticulata and the tadpole, D . melanostictus were 63 and 72 μg/L respectively. Corresponding LC50 values for cadmium were 76 and 431 μg/L. The most sensitive species for copper and cadmium was the crustacean, M . macrocopa . The highest tolerance for cadmium was shown by the amphibian, D . melanostictus tadpole whereas D . magna showed the highest tolerance to copper. Additional ecotoxicity data for copper and cadmium focusing on more tropical freshwater species are needed for derivation of water quality criteria for tropical freshwater life protection.
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    Determination of an eligible location for installation of a solar panel system in the University of Kelaniya using GIS
    (Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Heshani, A.L.S.; Athukorala, S.M.W.; Leelarathna, W.D.S.R.; Weerasinghe, V.P.A.
    According to the international energy agency, the role of renewables continue to increase in the electricity, heating and cooling and transport sectors. Newly develop technology in photovoltaic cells that have the potential to dramatically increase solar power generation in the next two decades. Being closer to the equator, Sri Lanka has a great opportunity to have solar energy throughout the year almost 5-6 hours per day. Sri Lankan power supply organizations are mainly depending on diesel, coal and hydro power. Still we do not have enough sources to supply electrical energy throughout the country. All the energy sources except hydro power are not considered as environmental friendly since they emit high amount of carbon to generate power. Being the first Green University in Sri Lanka, University of Kelaniya has initiated many approaches for energy conservation within the University. This study was carried out to find out the most suitable location within the University for installation of a solar panel system using ArcGIS software. For this, surface area of roof of buildings, height of buildings, elevation of the land, disturbance from other structures such as buildings and trees were selected. Map layers were created by using high resolution satellite image. Surface elevation profile was created by using available contour lines. Building layer was digitized from the satellite image using ArcGIS software. After overlaying all layers together suitable roofs were selected for the solar panels to install. In order to find possible energy in the area, meteorological data was collected including minimum and maximum atmospheric temperature, rainfall, and sunshine hours from Welisara meteorological station which is the nearest meteorological station to the University. The mean values of meteorological parameters obtained for the past 8 months were as follows; maximum atmospheric temperature of 28.28 0C and minimum of 26.02 0C, rainfall of 171.92 mm and sunshine hours were 7.6 hours. After selecting suitable buildings from the map, visual observation was done to calculate roof area of each building manually. The building with the highest surface area and minimum disturbance from adjacent structures was selected as the best suited location. The best suited location was selected and also it shows the highest monthly average consumption of electricity among other university buildings. Apart from that suitable lands also can be considered. But as the availability of lands in the university premises is a limited factor, priority was given to the rooves of the buildings. It is easy to make 3D view of the University by using 3D Analyst, if there is a higher resolution Digital Elevation Model (DEM). Roof structure and the shape can be used to maximize the efficiency of solar panels. GIS can be used as a supportive tool in optimization of determining the best suited location for the solar panel installation.