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.
Suspended matter and nutrient are major factors for water pollution studies and this study is focused on behavior and loading of suspended sediment and nutrient in Upper Kotmale Basin (UKB). Nanu Oya, Dambagasthalawa Oya and Agra Oya are three major streams fed by Kotmale Oya proper in UKB. Eight sampling locations were selected considering all major rivers and eight months samples were collected on monthly basis. Data analysis is used cluster analysis and descriptive statistic was used for analysis of nutrient and suspended sediment loading in streams. Results reveal that, highest nutrient loads bring by Nanu Oya and calculated mean daily nutrient loads namely; ammonia-N, nitrite-N, nitrate-N, and dissolve phosphate were found to be in
Madu Ganga is the latest addition to the Ramsar International Convention of Wetlands. Najas marina is an alien aquatic plant and 0.5 m long that are often branched toward the upward portion of the plant. The objective of the study was to study the impact of salinity and nutrients for the growth of Najas marina. Samples were collected for analysed water quality parameters from March, 2006 to January 2007 in the lagoon. Mapping was done using Garmin GPS map 76CS and Arc GIS used to developed maps.Mean nutrient such as, nitrate nitrogen, ammonia nitrogen and orthophosphate concentrations were observed 0.26 ± 0.3 mg/l, 0.057 ± 0.04 mg/l, and 0.354 ± 0.77 mg/l subsequently. Mean salinity variation in bottom and surface are 6.38 ± 6.65 ppt and 4.31 ± 4.68 ppt. Higher bottom salinity was observed in location number 02 (near to sea mouth) and Najas marinawas not present in the area. Najas marina was also not recorded in upper part of the lagoon and fresh water streams studied. High density of Najas marina plants were observed in sampling location 07, 08 and 09, because of the high nutrient concentration flowing through feeding tributaries. More than 25 % of lagoon area was covered by Najas marina.
The water pollution trends in the Ambewela reservoir at the uppermost catchment of Kotmale River was assessed through a study on chemical and bio monitoring programme that carried out from March to October 2008.The mean average value (mean ± SD) of the nitrate, nitrite, phosphate and ammonia concentrations in Ambewela reservoir were 0.780 ± 1.386 mg/l, 0.103 ± 0.223mg/l, 0.051 ± 0.061mg/l and 0.218± 0.261 mg/l whereas values for the streams selected from Dambagasthalawa Oya were 0.985 ± 0.902 mg/l, 0.099 ± 0.207mg/l, 0.038 ± 0.026 mg/l and 0.085± 0.077 mg/l respectively. Average Chlorophyll-a values of the reservoir were 17.85 ± 17.858 mg/m 3 and 8.30 ± 4.686 mg/m 3 for other two streams accordingly. Average BOD values of the reservoir were 8.06 ± 3.494 and 4.25 ± 2.251 for other two streams correspondingly.The bio monitoring studies also clearly showed sudden records of huge colonies of Hydra (approximately 258/cm 3 ) in the reservoir from time to time. This phenomenon was found in relatively dry period that directly coincided with intensified use of agro chemicals. Moreover, steady population of Chironomid (average population density 208/cm 3 ) that is commonly accepted pollution indicator was reported at Ambewela reservoir throughout the study period.Therefore, both chemical and bio monitoring studies indicate eutrophic condition in Ambewela reservoir in which long run might affect on the ecology of the entire ecosystem. Hence prompt mitigatory action should be implemented to avoid further depletion.
The main objective of this study was to assess the difference of water quality of Bomuruwella reservoir before and after the dredging operations of the reservoir, which was carried out between June and September 2014. Water sampling was conducted from February to December 2014 on monthly basis at randomly selected 10 sampling locations. Dissolved oxygen (DO), pH, turbidity, electrical conductivity (EC), total dissolved solids (TDS), and salinity were determined in situ, and collected water samples were analyzed in accordance with the standard methods. All statistical analyses were performed using MINITAB 14 statistical software. Mean values of EC, DO, Turbidity, TSS, ammoniacal-nitrogen, nitrate-nitrogen, total hardness and Ca hardness, total discharge of nutrients increased while orthophosphate, nitrite-nitrogen, alkalinity, and chloride decreased after dredging operation. There were significant differences (p<0.05) between all the mean water quality parameters measured except for EC, BOD, and nitrite-nitrogen following the dredging. Also, the mean total discharge ammoniacal-nitrogen, nitrate-nitrogen, nitrite-nitrogen and orthophosphate before and after dredging period from sluice gate were 4,031.1 m 3 /day; 7,986.6 m 3 /day, 2,747.4 m 3 /day; 208.9 m 3 /day and 388,469.4 m 3 /day, 309,479.8 m 3 /day; 29,324.49 m 3 /day, 2,157.67 m 3 /day, respectively. In conclusion, dredging operation had impact on the water quality parameters in the reservoir, except chloride, alkalinity, orthophosphate, DO and nitrite, where they improved after dredging.
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