Nadeesha Dilani Hettige

The main goal of this study was to develop a model for organic pollution assessment. Seven sampling sites in six rivers in the Rawang sub-basin, Selangor River, Malaysia, were selected with one reference site. The sampling sites near the fish farm were used to develop the model. SR2 was used for the validation of the developed model. Benthic macroinvertebrates and water sampling were conducted from April 2019 to March 2020. The Principal Components Analysis (PCA) and regression were conducted to select the most representing benthic macroinvertebrates family. Based on the score value (variance coefficient) of each benthic macroinvertebrates family, the cumulative score value of each sampling site was calculated (i.e., 18=6 sampling sites x 3 replicates). The nine benthic macroinvertebrate families (Baetidae, Libellulidae, Protoneuridae Chironomidae, Curbicullidae Hydropchysidae, Tubificidae, Lumbriculiade, and Naididae) were identified using PCA and regression. The cluster analysis and mean confidence intervals were used to classify water quality classes precisely. Finally, three different value scales were produced to represent the level of contamination (i.e., 0.87 as clean status). The newly developed model was validated. The results produced after validation were better than the water quality status from other studies based on the BMWP/BMWPThai score. This study concludes that the developed model can evaluate river organic contamination successfully. model can evaluate river organic contamination successfully.

Currently, an aquatic ecosystem of Sri Lanka is faced with acute environmental problems due to trace metal pollution. Bomburuella is one of reservoirs situated in Nuwara-Eliya District, Sri Lanka. Trace metal pollution of this reservoir has taking placed due to various anthropogenic activities. Therefore, it is very important to determine the cause for bioaccumulation of trace metals in fish tissues. The aim of this study was to determine the levels of selected trace metals in the tissues of fish species (Cyprinus carpio/Common Carp). Samples were analyzed using Atomic Absorption Spectroscopy (AAS) to determine selected trace metals namely mercury (Hg), lead (Pb) and cadmium (Cd). Results revealed that, the mean concentration of trace metal namely Hg, Pb and Cd recorded as 0.56 ± 0.15 mg/kg, <Limit of Detection (LOD) and 0.03 ± 0.00 mg/kg whereas Hg and Cd concentration of the fish sample in the reservoir were ranging from 0.44 to 0.73 mg/kg and 0.02 to 0.03 mg/kg respectively. However concentration of Pb was less than limits of detection (0.52 mg/kg). The detected average concentration of Cd in fish tissue was below the standard limits (<0.05 mg/kg) defined by European Union for (Commission

The coastal area of the Western Province is faced with an acute environmental problem due to undesirable pollution of its waters from various wastes. The overall objective of this research was to determine the present status of water quality along the coastal line in the Western Province. In addition, an attempt was made to suggest recommendations to mitigate the pollution levels. The study was carried out from November 2011 to April 2012 and sampling was done on a monthly basis from Bentota to Negombo in selected coastal area. Dissolved oxygen (DO), water temperature, pH, turbidity, conductivity, total dissolved solids (TDS) and salinity were determined in situ and water samples were subjected to laboratory analysis using standard methods. Coastal water quality results revealed that, the average ammonia concentration (0.22 ± 0.16) mg/L and water temperature (30.0 ± 3.8) 0 C were below the maximum permissible limits of the proposed ambient water quality standards for Sri Lankan coastal waters. Average pH (7.91 ± 0.34) was within the ideal pH range for above standards whereas the mean concentration of DO was below the saturation level. An average value determined for Biochemical Oxygen Demand (12.08 ± 4.47) mg/l was much higher than the permissible threshold limit (>5 mg/l) which indicates the gross organic and inorganic pollution in all selected sampling locations in western coast. Proposed ambient coastal water quality standards should be modified using coastal water quality monitoring data and expert views and comments. Further studies needed to determine heavy metal concentration and bacteriological parameters to obtain clear picture of the pollution status.