An assessment of water quality and pollution in Puranawella fishery harbour, Dewinuwara, Sri Lanka.

  • Niroshana K
  • Asanthi H
  • Kumara P
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Fishery harbours in Sri Lanka have been facing severe pollution problems since recent past. However, a systematic monitoring of the pollutant load has not been done. This study was carried out at Puranawella harbour, located in the southern coast of Sri Lanka, with the objective of assessing the severity of the pollution level. Investigation was carried out at seven sampling stations at three week intervals during the period from December 2010 to February 2011. Spatial and seasonal variations of physico-chemical parameters and phytoplankton abundances were examined together with bacteriological analyses. Among the characteristics studied, significant differences between sampling stations were observed for water transparency, chemical oxygen demand, orthophosphate, nitrite, oil and grease content of surface and bottom water as well as Cu and Pb in water and sediment. Water temperature, pH, salinity, total suspended solids, total dissolved solids, dissolved oxygen, biological oxygen demand, Pb in sediment and phytoplankton abundance showed significant variations among sampling months. Harbour water was characterized significantly by poor transparency (0.35m - 4.00m) and high amount of total suspended solids (0.015 - 0.072 gl-1 ), total dissolved solids (6.98 - 43.79 gl-1 ), high biological oxygen demand (0.44 - 8.08 mgl-1 ), high chemical oxygen demand (0.78 - 23.4 mgl-1 ), high orthophosphate (0.008 - 1.58 mgl-1 ) and a high proportion of Nitrite (0.02 - 1.83 mgl-1 ) indicating a severe eutrophication. Biological oxygen demand close to harbor jetty was 4.46 mgl-1 , which exceeded the recommended quality standard. Orthophosphate in surface waters exceeded the limit 0.015 mgl-1 , amount necessary for the establishment of heavy algal blooms. Oil and grease content of surface (9 - 82 mgl-1 ) and bottom water layers (22 - 241 mgl-1 ) inside the harbour also exceeded the recommended value of 10 mgl-1 . The concentration of Cu and Pb in water exceeded the standard value of 0.5 mgl-1 . MPN value of total coliforms (per 100 ml) ranged between 5 and 2400, which also exceeded the recommended standards. The phytoplankton density ranged between 16356 and 62500 cells/m3 . Results of this study revealed that the water quality of the harbour has been degraded and harbour is subjected to severe oil pollution, organic pollution and microbial contamination. Since this study was carried for only 3 months, a yearlong study is required to come to stronger conclusions.




Niroshana, K. H. H., Asanthi, H. B., & Kumara, P. B. T. P. (2013). An assessment of water quality and pollution in Puranawella fishery harbour, Dewinuwara, Sri Lanka. Journal of the University of Ruhuna, 1(1), 23.

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