Browsing by Author "Najim, M.M.M."

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A Determination of air pollution in Colombo and Kurunegala, Sri Lanka, using energy dispersive X-ray fluorescence spectrometry on Heterodermia speciosa
(Scientific and Technological Research Council of Turkey (TÜBİTAK), 2011) Gunathilaka, P.A.D.H.N.; Ranundeniya, R.M.N.S.; Najim, M.M.M.; Seneviratne, S.
Sri Lanka is facing severe environmental problems such as air and water pollution due to rapid industrialisation and urbanisation. Because there have not been many studies on heavy metal pollution in Sri Lanka, the present study attempts to contribute to the literature a determination of metal pollution using indicators found in lichen specimens. Our study utilised energy dispersive X-ray l uorescence spectrometry to determine element concentrations resulting from air pollution in the lichen species Heterodermia speciosa Wulfen. h ese samples, collected from Colombo and Kurunegala, Sri Lanka, were analysed using the energy dispersive X-ray l uorescence (EDXRF) method in order to determine the concentrations of 13 dif erent elements. A radioisotope excited X-ray l uorescence analysis was applied to the elemental analysis of lichens using the method of multiple standard addition. Our qualitative analysis of spectral peaks showed that the samples contained potassium, calcium, titanium, iron, manganese, copper, zinc, lead, bromine, rubidium, strontium, yttrium, and gallium. Samples from the environment around Colombo, which is a highly congested urban area with much industrial development, were found to be more polluted when compared with Kurunegala, a city that is less congested and without industries. Concentrations of K, Ca, Ti, and Fe were always higher than other elemental concentrations in the lichens we analysed, a fact attributed to the proximity to the sea or exposed earth crustal sources. From the elements reported from the 2 cities, K, Ca, Ti, Fe, Mn, Zn, and Pb were reported at concentrations higher than background levels. Levels of Pb and Zn in samples from Colombo were higher than those from Kurunegala, relecting the increased vehicular trai c. h is study reveals that the common lichen species Heterodermia speciosa can be used as an indicator lichen to analyse the pollution level and other elements in the atmosphere.
Adapting Sri Lanka to Climate Change: Approaches to Water Modelling in the Upper Mahaweli Catchment Area
(Climate Change Research at Universities. Springer, Cham, 2017) Gunawardena, M.P.; Najim, M.M.M.
Water flow and water quality changes in surface water bodies due to climate change is a major problem worldwide, typically in river eco-systems. To address these issues, proper monitoring of river flow variations and water quality is necessary, but daily monitoring and data collection is greatly time consuming and costly. Therefore, a study was done with the objectives to calibrate and validate the HEC-HMS 3.5 and HEC-RAS 4.1.0 models to simulate flow variation and water quality variations respectively in Nillambe Oya, Sri Lanka. The development of such models are a significant requirement in the present scientific world to predict river flow and water quality variations as an adaptation for the climate change. The HEC-HMS 3.5 model was used to generate flow which is needed for HEC-RAS 4.1.0. Daily flow data for five years (from October 1991 to September 1996) were used to calibrate the HEC-HMS 3.5 model and another set of daily flow data for five years (from October 1994 to September 1999) were used to validate the model. HEC-RAS 4.1.0 model was calibrated using water quality data collected and analyzed in five days. The validity of the calibrated model was evaluated using water quality data collected in the other four days. The calibrated and validated HEC-HMS 3.5 model reliably predicted the flow in Nillambe Oya. The calibrated and validated HEC-RAS 4.1.0 model simulated Dissolved Oxygen (DO), Biological Oxygen Demand (BOD) and Nitrate Nitrogen (NO3-N) splendidly. Orthophosphates was also predicted reliably by the model, but the simulation of organic Phosphorus was not that sensible.
AGNPS Model Assessment for a Mixed Forested Watershed in Thailand
(ScienceAsia, 2006) Najim, M.M.M.; Babel, M.S.; Loof, R.
Watershed modeling, as a tool to identify environmental problems, is becoming more popular. The modeling approach will allow evaluating present scenarios and possible remedial measures and strategies. The present study attempts to verify the suitability of the Agricultural Non-Point Source (AGNPS) pollution model developed for an agricultural watershed, for a mixed forested watershed. The study watershed, Huai Nong Prong in Southeastern Thailand, is a mixed forested watershed with 26% forest, 25% mangrove forests, and 36% agro-forests. Extensive fieldwork was completed to collect data and information needed for the model preparation and application. The study revealed that the AGNPS model produces satisfactory results regarding runoff volume and soluble nitrogen yields for the watershed. The sediment yield prediction is marginal for the selected watershed, partially attributed to the mangroves and the pools in the streams, which act as sediment traps. This suggests that mangroves in the downstream end of the watershed could act as natural wetlands capable of neutralizing or reducing environmental problems created by a watershed. The model, however, could not accurately simulate the peak flows, suggesting the peak flow simulating approach in AGNPS does not suitably predict peak flows from mixed forested watersheds.
An overview of policy and institutional distribution for drinking water supply in the Arsenic affected areas in Bangladesh
(The Environ Monitor, 2008) Haque, M.A.; Najim, M.M.M.
Application of PRA tool to study fish diversity variations due to small tank renovation - A case study from Galgamuwa D.S Division
(Research Symposium 2009 - Faculty of Graduate Studies, University of Kelaniya, 2009) Nishantha, K.P.L.; Najim, M.M.M.; Dangalla, N.K.
Small tank renovation has been practiced with the intention of improving agricultural productivity and alleviation of rural poverty in Sri Lanka since the independence. Small tank renovation process influences changes in aquatic habitat that could have impacts on the fauna and flora in the tank systems. Small tank renovation process does not consider the possible changes that could take place on aquatic fauna and flora. This study was conducted to assess the variations that took place in bird diversity in the small tanks due to tank renovation utilizing Participatory Rural Appraisal (PRA) and questionnaire survey. Twelve small tanks from Galgamuwa D.S. Division that were renovated within last 15 years were selected using stratified random sampling technique. Randomly selected 150 farmers responded to the questionnaire survey while 400 farmers were engaged in the 12 PRA surveys conducted to cover the 12 study tanks. Results from the questionnaire and PRA surveys were used to assess the presence and abundance of fish before and after tank renovation. Tank renovation has changed the living environment of the fish and brought in some changes in the fish population. The population of carnivores has decreased due to tank renovation according to the statistical analysis. This could be due to silt deposition on gills and eggs of those species during the renovation process. The population of the omnivores has increased while fish like barbs has also increased due to reduction of the predators.
Application of the HEC-HMS model for runoff simulation in a tropical catchment
(Environmental Modelling & Software, 2013) Halwatura, D.; Najim, M.M.M.
Assessment of Agricultural NonPoint Source Model for a Watershed in Tropical Environment
(Journal of Environmental Engineering, 2004) Najim, M.M.M.; Babel, M.S.; Loof, R.
Very little work on the application of watershed modeling has been done in the tropical climatic conditions of Thailand to explore the nature of environmental problems arising from nonpoint source pollution due to agricultural activities, and to evaluate possible remedial measures and strategies. The present study attempts to verify the suitability of a nonpoint source pollution model, the Agricultural NonPoint Source model, for the Huai Nong Prong watershed in Southeastern Thailand. Extensive fieldwork was carried out to collect data and information needed for the model preparation and application. The study has revealed that simulated runoff volume, sediment, and nutrient yield from the watershed with mixed land use and relatively high slopes match favorably with observed data. For the ten rainfall events simulated, the coefficient of performance, a measure of model efficiency (equal to zero for a perfect match), was 0.09, 0.47, 0.09, and 0.03 for runoff volume, sediment yield, total nitrogen, and total phosphorus, respectively. The model, however, could not accurately simulate peak flow rates, suggesting the need for changes in the modeling approach or governing equations and relationships to calculate peak discharges in a tropical environment.
Assessment of continuous wet day rainfall frequency distribution in the intermediate zone in Sri Lanka
(University of Sri Jayawardhanapura, 2013) Jayasuriya, M.T.; Najim, M.M.M.
Assessment of current water pollution status and accumulation of trace metals in Mugil cephalus from Negombo estuary
(Journal of Threatened Taxa, 2021) Najim, M.M.M.; Kithsiri, H.M.P.
Industrial and domestic solid waste dumping are the major pollution sources polluting the Negombo estuary. Polluted water and sediments in the estuary may cause heavy metals accu mulation in fish. Therefore, this study was aimed to assess physico - chemical parameters in water, heavy metals (Zn, Pb, Hg, Cd, Cu and Cr) in water and fish tissues, to compare the levels of metals in fish tissues with the available maximum recommended standards. The study was carried out from January to December 2016 and monthly sampling was done from the selected sampling sites. Physico - chemical parameters and metal levels were detected through standard methods. Water quality results revealed that temperature, salinity, pH, EC, TSS, BOD and nutrient levels were below the maximum permissible limits and COD levels were higher than the discharge of industrial wastewater quality standards of the CEA, Sri Lanka. According to the results, metal levels in water of the estuary were below the tolerance limits for the wastewater standards of the CEA except for Hg. In the Northern region of the estuary, higher Pb, Cu and Cr levels were reported from the fish species collected. As the “X-Press Pearl” shipwreck has posed a serious threat to the Negombo estuary, this study can be considered as a baseline for the future studies on water and sediment pollution and bioaccumulation of heavy metals in edible fish species from the estuary.
Assessment of rainfall frequency distribution in the intermediate zone of Sri Lanka
(Sri Lanka Association for the Advancement of Science, 2013) Jayasuriya, M.T.; Najim, M.M.M.
Assessment of the climate change variability in the intermediate zone of Sri Lanka through continuous wet day rainfall frequency distribution analysis
(Symposium proceedings of the Water Professional?s Day, 2013) Jayasuriya, M.T.; Najim, M.M.M.
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.
Benthic macro-invertebrates as environmental flow indicators – a case study: Gurugoda oya, Sri Lanka
(Sri Lanka Association for the Advancement of Science, 2014) Munasinghe, D.S.N.; Najim, M.M.M.
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.
Bird diversity variation due to small tank renovation in dry zone of Sri Lanka – A case study from Galgamuwa D.S Division
(Research Symposium 2009 - Faculty of Graduate Studies, University of Kelaniya, 2009) Nishantha, K.P.L.; Najim, M.M.M.; Dangalla, N.K.
Tank renovation programs implemented in Sri Lanka were intended to increase agricultural productivity but did not take into account the possible impacts on the fauna living in the tank environment. Tank renovation programs in Sri Lanka might have influenced changes in avian fauna inhabited around a tank environment. Therefore, a study was conducted to assess the variations that took place in bird diversity in and around the tanks due to tank renovation. Twelve small tanks from Galgamuwa D.S. Division were selected using stratified random sampling technique. Randomly selected 150 farmers responded to the questionnaire survey while 400 farmers were engaged in the 12 Participatory Rural Appraisal (PRA) surveys conducted to cover the 12 study tanks. Results from questionnaire and PRA surveys were used to assess the presence and abundance of birds before and after the tank renovation. Questionnaire survey identified that Cormorant species population has increased with the tank renovation. Fifty nine percent of farmers said that Cormorant (Phalacrocorax niger) could be seen rarely before the renovation but 85% of them reported that there is an increase of the Cormorant population after the renovation. Removal of tank vegetation has given them a favorable environment to catch their pray. The White-breasted Water hen (Amauronis phoenicurus) and Purple Swamp (Porphyrio porphyrio) that used the tank vegetation as the habitat and breeding site are reduced due to tank renovation. This has reduced the environment suitable for egg laying. PRA analysis identified an increase of Lesser Whistling Teal (Dendrocygna javanica) in some tanks and a decrease in some other. This study showed that tank renovation could influence the presence of different bird species due to the changes that take place in and around tank environments due to the tank renovation programs.
Calibration of a venturi fertilizer injector for efficient micro irrigation
(Symposium proceedings of the Water Professional?s Day, 2006) Najim, M.M.M.; Abeywardana, S.C.; Jayakody, K.P.K.; Rambanda, M.
Changes in amphibian and reptile species living around tank environments due to r enovation of small tanks in the dry zone of Sri Lanka – A case study from Galgamuwa D.S Division
(Research Symposium 2009 - Faculty of Graduate Studies, University of Kelaniya, 2009) Nishantha, K.P.L.; Najim, M.M.M.; Dangalla, N.K.
Small tank renovation programs were implemented in Sri Lanka to increase the land area under cultivation. The renovation activities could have positive and negative impacts. The environmental impacts due to tank renovation have not been studied in Sri Lanka. Therefore, a study was conducted to assess the changes that took place in amphibian and reptile species living in and around the tanks due to tank renovation. Twelve small tanks from Galgamuwa D.S. Division were selected using stratified random sampling technique. Randomly selected 150 farmers responded to the questionnaire survey while 400 farmers were engaged in the 12 Participatory Rural Appraisal (PRA) surveys conducted to cover the 12 study tanks. Results from questionnaire and PRA surveys were used to assess the presence and abundance of amphibians and reptiles before and after tank renovation. Some amphibians and reptiles lived in the tank environment have either reduced in population or disappeared after the renovation. Significance testing at 95% confidence level revealed that tortoise and water monitor populations have reduced after the tank renovation. Eighty seven percent (87%) and 72% of the farmers responded that tortoises and monitors were abundant before the tank renovation, respectively in the tank environment while only 47% and 42% agree to it, respectively after the tank renovation. According to the PRA analysis, before the tank renovation, the monitor was the second abundant but it has reduced to the sixth most abundant species after the tank renovation. Bulnawa tank was identified as the tank with the highest population of reptile species before the renovation process but after the renovation Medawachchiya and Mahagalkadawala showed higher populations. This study showed a decrease in the population of reptiles after the renovation but the amphibians do not show any variation in population
Changes in mammal abundance due to small tank renovation – A Case Study from the Dry Zone of Sri Lanka
(Research Symposium 2010 - Faculty of Graduate Studies, University of Kelaniya, 2010) Dangalla, N.K.; Najim, M.M.M.; Nishantha, K.P.L.
The tank renovation programs in Sri Lanka were implemented with the sole objective of increasing agricultural productivity without considering the possible impacts on the environments. A study was conducted to assess the impact of tank renovation on mammal diversity around renovated tanks. Twelve small tanks from Galgamuwa D.S. Division were selected using stratified random sampling technique. The questionnaire survey was responded by 150 randomly selected farmers while 400 farmers were engaged in the 12 PRA surveys covering each study tank. Results from these surveys were assessed to evaluate the abundance of mammals before and after the tank renovation. According to the questionnaire survey deer, mongoose species and sambur populations have decreased with tank renovation. Twelve percent of the respondents are with the opinion that many deers (Axis axis ceylonesis) could be seen before the tank renovation but 79 % of them reported that deer could not be seen abundantly after the renovation. According to the farmers responses, Sambur (Cervus unicolor unicolor) could not be seen after the tank renovation. The PRA analysis identified an increase in mammal species in Monnankulama tank while a decrease in Ihalagama tank. The other tanks did not show any changes in the overall mammal populations. The reduction in the population of these mammals could be due to the increased human, vehicular and machinery movements due to the tank renovation. In additions, regular removals of vegetation cover from the tank surroundings, increased crop cultivation and settlements could have contributed to the changes in mammal diversity. According to the PRA survey, least mammal density is reported from Pahala Pulanchiya, Inhale and Pahala Palukandawa, Kurundankulama and Diwullawa tanks. The main reason for the least population could be linked to the closeness to the main roads and the settlements.
Climate Change Induced Variations in Rainfall Patterns and Potential Adaptation Options of DL1b Agro-Ecological Zone of Sri Lanka: A Case Study
(Institute of Biology Sri Lanka, Colombo., 2020) Udayanga, L.N.W.B.A.; Najim, M.M.M.
An analysis of the shifts and trends of climate patterns with respect to wet and dry events and rainfall seasonality is vital for the effective planning and management of water resources in tropical countries such as Sri Lanka, which have agriculture-based economies. Hence, temporal and spatial variations of climate extremes and rainfall seasonality in Sri Lanka, were evaluated in the DL1b Agro-Ecological Zone through the Standardized Precipitation Index (SPI) and Seasonality Index (SI) utilizing 58 years of daily rainfall data of five selected localities. The Chi-square test of independence was used to statistically compare the percentage occurrence of each event recorded during 1961-1988 and 1989-2018. The dryness of all study areas denoted increments in terms of both severity and frequency of occurrence in accordance with SPI. However, among the studied localities of the DL1b agro-ecological zone, only the increment of dryness in Vavuniya remained statistically significant (Χ2 (df = 4) <9.78; P=0.04) at 95% level of confidence. Rainfall seasonality of the localities was characterized with a markedly seasonal climatic condition with a long, dry season (0.95 – 0.97) with no significant variations and shifts. Cultivation of low water demanding crops, adjustment of cropping seasons, use of more efficient water smart irrigation methods, implementation of agro-forestry systems and employment of smart and integrated watershed management practices could be recommended as potential adaptation measures to compensate the impacts of climatic change.
Comparative evaluation of three environmental flow calculation methods at Ketawala anicut of Aththanagalu Oya, Sri Lanka
(Department of Zoology and Environmental Management, University of Kelaniya, Kelaniya, Sri Lanka., 2016) Udayanga, N.W.B.A.L.; Najim, M.M.M.
Calculation of Environmental Flows (EFs), which are required for the sustenance of aquatic ecosystems in their original pristine state, often emerge as a prominent challenge to the sustainable management of water resources due to their complicity and difficulty of estimation. Being a tropical country that is heavily depended on its agriculture based economy, Sri Lanka often face the challenge of EF estimation during diverse irrigational and drinking water extractions. Lack of technology and expertise, and limitations in the long-term data have directly contributed for the wide utilization of rapid EF estimation methods. Therefore, the current study intends to evaluate the performance of such three widely practiced EF estimation methods, namely Tennant, IUCN and CEA methods for the EF estimation at Ketawala irrigational scheme. The Hydrologic Engineering Centre - Hydrologic Modelling System (HEC-HMS) version 3.5 model was calibrated and validated for the Aththanagalu Oya catchment and the daily river flow values for the past thirty five years (1981-2015) were generated at the pre-weir of the Ketawala anicut. The flow duration curve at the pre-weir of the Ketawala anicut was constructed (via the Gumbel approach) using the above simulated flow regime and the EFs that are applicable for the anicut were estimated via Tennant, IUCN and CEA methods in accordance with the standard methodologies. The Tennant method recommended an EF regime of 4.08 m3/s to be maintained at the post weir of the Ketawala anicut, while IUCN and CEA methods recommended EFs of 11.11 and 11.91 m3/s, respectively. Yet, EFs recommended by all these methods mostly remained higher than the average monthly flows in the dry season while considerably lower than the average monthly flows in the wet season at Ketawala, limiting the practical applicability of the estimated EFs. Furthermore, all these methods remained subjective and less responsive to the variations in the hydrological regime, while neglecting other major ecological components (biota and physic-chemical factors etc.) in an aquatic ecosystem. Hence, regardless of their wide applicably for EF estimation in Sri Lanka, the Tennant, IUCN and CEA methods failed to yield practically and environmentally acceptable EFs for the Ketawala anicut.