Browsing by Author "Abeygunawardena, A.P."

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    Soil Characteristics of Turtle Nesting Beaches in Southern Coast of Sri Lanka
    (Uva Wellassa University of Sri Lanka, 2020) Srimali, A.B.K.M.; Thilakarathne, E.P.D.N.; Abeygunawardena, A.P.; Egodauyana, K.P.U. T.; Abeygunawardena, C.J.
    There are seven species of marine turtles living in the world and five of them are occurring in Sri Lanka. All those five species: Green Turtle (Chelonia mydas), Olive Ridley (Lepidochelys olivacea), Hawksbill (Eretmochelys imbricata), Loggerhead (Caretta caretta) and Leatherback (Dermochelys coriacea) are nesting on Southern coastal belt of Sri Lanka and it comprises with largest marine turtle rookeries. Although, many characteristics of beaches are affecting turtle nesting; sand composition, sand porosity, vegetation cover, debris composition, soil temperature and soil pH level are considered as majors. Here eight most prominent turtle nesting beaches on the Southern coast: Yala, Bundala, Rekawa, Kalamatiya, Ussangoda, Habaraduwa, Mirissa, and Kosgoda were selected to study the sand characteristics since there is a lack of studies regarding this. The studied characteristics are sand porosity, sorting coefficient (Sφ) and mean diameter (Mn φ) and sorting level of beaches by collecting sand samples using piston core sampler up to 50cm depth level. Average sand porosities of different sites were as 28.67, 43.86, 40.77, 50.56, 30.32, 42.51, 55.23 and 21.43% while average sorting coefficient were as 0.56mm, 0.45mm, 0.60mm, 0.60mm, 0.77mm, 0.33mm, 0.95mm and 0.32mm respectively. Average mean diameters of sands of different sites were as 0.45mm, 0.34mm, 0.48mm, 0.50mm, 0.70mm, 0.24mm, 0.97mm and 0.23mm while average sorting levels were as 1.09, 0.85, 0.91, 1.02, 0.97, 0.71, 0.87 and 0.69 respectively. Among these sites, Mirissa has the highest porosity, sorting coefficient and mean diameter of sands. Yala and Kalamatiya have poorly sorted soil and other sites have moderately sorted soil. According to the literature, Kosgoda and Rekawa have the highest turtle nesting frequency. However, other characteristics of beaches and different turtle populations have to be incorporated by conducting more researches to afford strong inference on turtle nesting. Keywords: Species, Coastal characteristics, Sand, Rekawa, Turtle population of Sri Lanka
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    Study on Utility of Crassostrea madrasensis Oyster Shells for Water Quality Improvement: An Alternative for Wastewater Treatment
    (Uva Wellassa University of Sri Lanka, 2018) Senadeera, R.P.; Thushari, G.G.N.; Abeygunawardena, A.P.
    Oyster shell is a waste residue in sea food industry, thus waste accumulation can be minimized by reusing shells in environmental applications. Most biogenic structures act as adsorbents and biofilters in wastewater treatment. This study focuses on analysis of the potential use of C. madrasensis Oyster shells for removal of contaminants. Removal efficiency of heavy metals (Cu/Cd/Cr) and other physicochemical parameters in wastewater were tested in 7 treatments (different levels of thermally treated crushed oyster shells: 5 g,7 g, 9 g, 10 g, 11 g, 13 g and 15 g) for 24 hrs contact period. As results revealed, heavy metal adsorption capacity significantly changed with initial heavy metal levels and adsorbent masses (p < 0.05). Wastewater treated with 9g of shell powder had most efficient heavy metal removal rates for Cu (94.50 - 99.88%) and Cr (95.68 - 97.70%), while 99.16 99.64% of highest Cd removal rate was for wastewater treated with 11 g of oyster shells. Chitin in thermally activated shells make strong adsorption capacity, thus Oyster shells act as an effective biofilter in removal of heavy metals in wastewater. Average DO increased to maximum 37.73%, while highest removal efficiency of COD was 54.80% for 15 g of shell powder after 24hrs contact period. Initial PO43concentration significantly decreased with increased shell powder amount (p < 0.05) by flocculation of phosphorous with CaO in shells during 24hrs retention period. Highest phosphate removal capacity (85.9 - 56.2%) was found to be at 15 g of shell powder, indicating potential of application in eutrophicated water. Final pH was found to be increased to 6.5 - 8.5 which is optimum pH range for aquatic life. 24 hrs is the adequate contact period to equilibrate the reactions between adsorbent and waste water, hence preventing further releasing of chemicals of shells into treated water. This study reveals potential use of C. madrasensis Oyster shells for wastewater treatments as a low cost, environmental friendly alternative method.