Browsing by Author "Mendis, B.R.C."

Now showing 1 - 5 of 5

Assessment of Climate Extremes Based on SPI in WL1a Agroecological Zone - A Case Study from Kuruwita, Sri Lanka
(Sri Lanka Journal of Technology, 2020) Mendis, B.R.C.; Rasmiya Begum, S.L.; Najim, M.M.M
Drought and flood are the simple most significant climatological hazards in Sri Lanka, which primarily affects agricul tural productivity. Proper understanding and investigation of climatic extremes like drought and floods, plays a key role in planning and management of household, municipal, agricultural and industrial activities even with varied water availability. Therefore, the present study aimed to asses onset, severity and occurrence of drought and wet episodes (months) in Kuruwita region, which belongs to the Low Country Wet Zone Agro-ecological region using the Standardized Precipitation Index (SPI) at various time scales. SPI analyzed at 12 months’ time interval revealed that out of 45 years of study period (1961-2005), there were only four (1976, 1980-1981 and 1996) and six (1985-1986, 1988-1989, 2003-2004) drought and wet hydrological years, respectively. Further, the hydrological years 1981 and 2004 were identified as more affected years by drought and wet events, respectively, with relatively higher occurrence of climate extremes depicted by SPI, than normal conditions. The South-West monsoon (SWM) was found to be more prone to extreme climatic conditions, leading the Yala cropping season to become more abnormal with occurrence of more drought and wet months in Kuruwita. Therefore, the study suggests that implementation of proper mitigative measures like installation of rainwater harvesting systems, reuse or recycling of rainwater, cultivation of stress tolerant crop varieties, adaption of different cropping systems would be beneficial to minimize such adverse effects and for sustainable development in Kuruwita area
Assessment of water quality and identification of pollution status of Negombo estuary in Sri Lanka
(Sri Lanka Association for Fisheries and Aquatic Resources, 2015) Mendis, B.R.C.; Najim, M.M.M.; Kithsiri, H.M.P.; Azmy, S.A.M.
Industrial pollution and domestic solid waste dumping are considered as the major pollution sources of the Negombo estuary. Based on the pollution inputs into the estuary, it is considered that different localities within the estuary are polluted at different rates. A study was done with the objectives to determine the levels of physico-chemical parameters of water quality with special reference to identified pollution sources. For this study, water samples were collected from fourteen sampling locations during one year study period from January to December 2014 and important physico-chemical parameters such as conductivity, Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), phosphate-P, Nitrate-N, Ammoniacal-N and heavy metal (Pb, Cd and Hg) levels were analyzed employing standard methods. The results revealed that the average conductivity of 24.8±13.6 ms/cm, concentrations of nitrate 0.81±0.87 mg/L, phosphate 0.27±0.31 mg/L and ammonia 0.15±0.27 mg/L levels were below the maximum permissible limits of the proposed tolerance limits for the discharge of industrial wastewater quality standards for Central Environmental Authority, 2001 in Sri Lanka. The values obtained on BOD 23.6 ±7.1 mg/L and COD 469.0 ±36.5 mg/L levels were much higher than the permissible threshold limits. Results indicated that the concentrations of heavy metals Pb, Cd and Hg in water were 0.01 to 0.005 ppm, 0.0 to 0.01 ppm and 0 to 0.013 ppm, respectively. The detected average concentration of mercury in water was above the standard limits. The results obtained for levels of BOD, COD and heavy metals revealed that high pollution takes place in industrial and domestic sewage sampling sites. The South region receives water mainly from Dandugam Oya which carries various effluents from Ekala industrial zone. East region receives discharge of effluents from mainly Katunayake industrial processing zone. North region of the estuary, the levels of BOD, COD and heavy metals in water were higher due to the discharge of industrial effluents and domestic solid waste into the estuary. The highest concentrations of BOD, COD and heavy metals were recorded in the Northern area followed by Southern, Eastern and Western regions indicating the pollution status of the estuarine water.
Bioaccumulation of Heavy Metals in the Selected Commercially Important Edible Fish Species Gray Mullet (Mugil cephalus) from Negombo Estuary.
(Journal of Environmental Professionals Sri Lanka,, 2015) Mendis, B.R.C.; Najim, M.M.M.; Kithsiri, H.M.P.; Azmy, S.A.M.
Consumption of fish contaminated with non essential heavy metals such as Pb, Hg and Cd metals which exceed the required limits pose a risk to human health. Bioaccumulations of heavy metals in fish depend on several factors such as increased levels of industrial pollution and domestic solid waste dumping in the estuary. Based on the pollution inputs into the estuary, it is considered that different localities within the estuary are polluted at different rates. The objectives of this study were to determine the non essential heavy metals concentration in fish tissues and assess the seasonal variations in the ecosystem. For this study, fish tissue samples were collected from nine sampling locations along the North (n =3), South (n=2), West (n=2), and East (n=2) parts of the estuary for a period of one year from January to December 2014. Fish tissue heavy metals levels were analyzed employing standard methods. Results revealed that the average concentrations (mg/kg) varied from Pb 0 to 0.15 ± 0.06, Cd 0.35 ± 0.16 to 1.04 ± 0.28 and Hg 0.0005 ± 0.0004 to 0.05 ± 0.046 mg/kg respectively. The detected levels were below the maximum permissible limits for hazardous substances in fish and fishery products for recommendation of FAO. The detected lead, mercury and cadmium contents in fish tissue were below the standard limits defined for each element < 0.5 mg/kg < 0.05 mg/kg and < 0.05 mg/kg respectively. Significant differences (P< 0.05) were observed for Pb and Hg depending on fish tissues. The levels of Pb and Hg metals in muscle tissue were lower than the standard limit for FAO. The value obtained on Cd 1.04 ± 0.28 mg/kg concentration was much higher than the permissible threshold limit observed in the north, south, east and west regions. The most prominent increases in Pb and Cd metal concentrations in fish tissue were found during the October, November and December study of 2014, which corresponded to peak periods from October, November and December which apparently coincided with the second inter monsoon of the island respectively.
Heavy Metals Levels in Water, Sediments and Edible Fish (Mugil cephalus) Tissues of Negombo Estuary, Sri Lanka
(NARA Journal, Volume 44,, 2015) Mendis, B.R.C.; Najim, M.M.M.; Kithsiri, H.M.P; Azmy, S.A.M.
Quantitative analysis of water quality and heavy metals in water, sediments and tissues of Grey Mullet (Mugil cephalus) from the Negombo estuary
(Colombo Journal of Multi-Disciplinary Research, 2015) Mendis, B.R.C.; Najim, M.M.M.; Kithsiri, H.M.P
The objectives of this study were to assess the levels of water quality and heavy metals of the water, sediments and fish tissues in the Negombo estuaries. For this study, samples were collected from sixteen sampling locations during the one year study period from January to December 2014. The results revealed that the average concentrations of ammonia, nitrate, pH, electrical conductivity, total suspended solids of 0.215±0.4mg/l, 1.08±0.98mg/l, 7.8±0.28, 29.6±1.56ms/cm, 29.2±0.35mg/l, levels were below the maximum permissible limits. Biochemical Oxygen Demand 24.8±1.3mg/l and Chemical Oxygen Demand 469.0±36.5mg/l levels were much higher than the permissible threshold limits of industrial wastewater quality standards for CEA,(2001) Sri Lanka. The results indicated that the concentrations (ppm) of heavy metals in water were Pb,0.01±0.0003; Cd,0.015±0.003; Hg,0.013±0.001; Zn,0.695±0.06; Cu,0.03±0.02; Cr,0.055±0.004 and Fe,0.485±0.04 respectively. The sediments concentrations (mg/kg) were Pb,7.95±0.95; Cd,1.06±0.23; Hg,0.001±0.52; Cu,0.042±3.2; Cr,14.30±1.5, Zn,154.25±3.2 and Fe,78.6±101.2 respectively. The concentrations (mg/kg) of metals in the fish tissues were Pb,0.57±0.48; Cd,1.045±0.28; Hg,0.05±0.046; Zn,119.2±111.3; Cu,4.60±1.64; Cr,5.22±2.49 and Fe,32.8±59.3 respectively. The highest concentrations of pollution status were recorded in the Northern region of the estuary.