Browsing by Author "Wijeyaratne, W. M. D. N."

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Application of Allium cepa bioassay to study the spatial variation of potential cytotoxicity in relation to water quality in the Dandugan Oya, Sri Lanka
(Research Symposium on Pure and Applied Sciences, 2018 Faculty of Science, University of Kelaniya, Sri Lanka, 2018) Wadasinghe, L. G. Y. J. G.; Wijeyaratne, W. M. D. N.
Water quality is an important indicator in measuring the health of aquatic ecosystems. Poor water quality can lead to ecological health impairment. Dandugan Oya is receiving industrial waste from multiple sources. In addition, the raw water for the public water supply in some suburban areas in the Gampaha District is obtained from the Dandugan oya. In this study, potential cytotoxic effects of the water in selected sites of the Dandugan Oya were assessed using Allium cepa bioassay. Surface water samples were collected from six sites (Site A: Urban site; B and D: Industrial sites; C: public water supply intake; E: Agricultural site; F: Reference site with pristine environmental conditions) at two month intervals from May to November 2017. Water samples were collected from each site (n=10) and temperature, pH, conductivity, biochemical oxygen demand (BOD), dissolved oxygen concentration (DO), total dissolved solids (TDS) and chemical oxygen demand (COD) were analysed using standard analytical methods. Potential cytotoxicity of these water samples were assessed using Allium cepa bioassay. Spatial variation of water quality and cytotoxic end points were analysed by ANOVA followed by Tukey’s pairwise comparison using MINITAB 14 software. Significantly lower DO was recorded from sites C (4.0 ± 0.3 mg/L) and D (4.3 ± 0.4 mg/L) and significantly high COD was recorded from site D (267.1 ± 56.5 mg/L) (p<0.05). Significantly high TDS and conductivity were recorded from sites A and B (p<0.05). Mean nuclear abnormalities of the root tip cells of the A . cepa bulbs exposed to the surface water samples collected from the study sites ranged from 9‰ to 83‰ where significantly higher (p<0.05) nuclear abnormalities were recorded from site C (83 ± 2.4‰). Occurrence of nuclear buds and condensed nuclei in the interphase cells of the A . cepa root tips exposed to water samples from the site C (18 ± 0.8‰ and 61 ± 2.0‰) were significantly higher compared to the reference site (2 ± 0.1‰ and 4 ± 0.1‰)(p<0.05). Further, Site D also showed significantly high (p<0.05) nuclear bud formation (15 ± 0.4‰) and highest binuclei formation (6‰ ± 0.2) compared to the reference site. The results of the present study indicated occurrence of potentially high cytotoxicity in the A . cepa bioassay in the water at site C, which is the water intake site of Dandugan Oya for public water supply. Therefore, further investigations on the identification of the active forms of cytotoxic contaminants and continuous monitoring of water quality in these sites of Dandugan Oya is important in order to maintain the ecosystem and human health.
Application of Life Cycle Perspective Costing (LCC) Use in European Union (EU) as a Green Procurement Tool for Cost-effective Public Procurement in the Health sector, Sri Lanka: A Survey-based Study
(Faculty of Commerce and Management Studies, University of Kelaniya Sri Lanka, 2023) Dinesh, K. L. S.; Liyanage, U. P.; Wijeyaratne, W. M. D. N.
In Sri Lanka public procurement guidelines should be followed by all government agencies, when they are required to procure goods, works, and services. The Objective of such guidelines is to ensure the value for money of the process. The Ministry of Environment, Sri Lanka has issued a national policy on sustainable consumption and production for Sri Lanka. Two sections of this policy document are reserved for public procurement and Health sectors. According to the policy document, the Ministry of Health should ensure sustainable practices at all levels in the health sector to be transformed into green work set up by 2030. The policy suggests applying sustainable public procurement (SPP) practices in all sectors and for each product or service that has a significant cost-saving impact. This paper mainly discusses Life Cycle Perspective Cost (LCC) and other Green and Sustainable evaluation practices regulated in health sector institutes in the European Union (EU) and reviews the possible adoption of those green and sustainable concepts to public procurement processes in Sri Lanka for cost-effective Public Procurement. The Adoption of green would maximize the value of public money while minimizing damage to the environment and maximizing economic, and social benefits to the public health sector in Sri Lanka.
Assessment of the relationship between rainfall patterns and human-elephant conflict in Nochchiyagama and Vanathavilluwa, Sri Lanka
(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Kalanika, G. I.; Rajapaksha, R. D. T.; Dahanayaka, D. D. G. L.; Padmalal, U. K. G. K.; Wijeyaratne, W. M. D. N.
Wilpattu National Park (WNP), the largest and oldest national park in Sri Lanka, spans across eight Divisional Secretariats (DS), where Human-Elephant Conflict (HEC) remains a significant concern. This research investigates the HEC in areas surrounding WNP and examines its correlation with rainfall patterns. A questionnaire survey was conducted in Nochchiyagama, the most densely populated of the eight DS divisions, to capture farmers’ perspectives on HEC. The HEC data were collected from the Department of Wildlife Conservation from 2015 to 2022 across the eight DS divisions and the highrisk and low-risk areas were identified. Additionally, rainfall data of Nochchiyagama and Vanathavilluwa DS divisions from 2015 to 2022 were examined to explore any potential relationship between rainfall and HEC incidents. Findings indicated that Cheddikulam and Karuwalagaswewa are high-risk divisions for HEC, while Rajanganaya is the lowest risk division. According to the survey, 71.3% of respondents believe that elephants invade villages searching for food where 45.5% of total responses indicate that coconut is the most attractive crop to elephants. Mangoes were the second most preferred crop (36.4%), followed by Kurakkan and paddy (26.4% each), and pumpkin, corn, and sugarcane (22.3%, 19.8%, and 16.5%, respectively). All respondents were familiar with elephant repellent methods, with "ali Vedi" being the most prominent. Additionally, 47.2% of respondents suggested establishing an electric fence to minimize conflict, while constructing ditches and using shotguns were recommended by 30.4% and 22.4% of respondents, respectively. Rainfall patterns in Nochchiyagama and Vanathavilluwa showed minor variations, with January-March and JuneSeptember being relatively dry periods, and March-June and September-December being rainy months. Despite 56% of survey respondents indicating that elephant incursions predominantly occur during the dry season, statistical analysis (Spearman test, p = 0.260, p = 0.347) found no significant correlation between HEC and rainfall in either division over the study period. In summary, while the study highlights areas and crops most affected by HEC and identifies community-preferred mitigation strategies, no significant correlation was found between rainfall patterns and HEC incidents. Although there is no direct relationship between rainfall and HEC, the HEC is influenced by the other proximate factors related with food availability which are in turn affected by the rainfall. Therefore, there might be an indirect relationship between rainfall and HEC in Nochchiyagama and Vanathavilluwa. Further research is recommended to confirm this idea and investigate seasonal variations in elephant movements and behaviors in other areas surrounding WNP to develop more effective mitigation strategies.
Bioaccumulation and health risks of chromium and cadmium in Basella alba with emphasis on Urea, muriate of potash and triple super phosphate mixtures
(National Science Foundation of Sri Lanka, 2024) Amarasena, M. D. M. C. K.; Wijeyaratne, W. M. D. N.
Basella alba is a commonly consumed green leafy vegetable in South Asian countries and it is considered as an economical source of essential vitamins and dietary fibers. Urea, muriate of potash (MOP) and triple super phosphate (TSP) mixture is the most commonly used inexpensive fertilizer mixture in the commercial cultivation of B. alba. This study was conducted to assess the effect of using a mixture of Urea-MOP-TSP on the bioaccumulation potential of cadmium (Cd) and chromium (Cr) by the leaves of B. alba. Pots treated with the Urea-MOP-TSP mixture and compost were maintained in a greenhouse with controlled light and temperature settings. The concentrations of Cd and Cr in the root zone soil, roots and leaves of B. alba were analyzed using an Atomic Absorption Spectrophotometer after acid digestion. The health risk of consuming B. alba was evaluated using the daily intake of metals, health risk index and cancer risk index. The results showed that Cd and Cr can bioaccumulate in the leaves of B. alba. The bioaccumulation potential of Cr was higher than that of Cd. Although the daily intake of Cd and Cr from B. alba were below the maximum values stipulated by the WHO, the cancer risk index indicated potential cancer risks based on Cd intake due to consumption of B. alba cultivated using the Urea-MOP-TSP mixture. Furthermore, the health risks associated with the hyper-accumulation of Cd and Cr in the edible parts of B. alba cultivated using compost were significantly less compared to that of the plants treated with the Urea-MOP-TSP mixture. Therefore, if B. alba is cultivated using chemical fertilizer, it is recommended to regularly monitor the concentrations of Cd and Cr in the cultivation soil, chemical fertilizer and in the edible parts of B. alba to prevent the excessive buildup of Cd and Cr along the food chain. In addition, it is recommended to identify the potential microbial assemblages that can be inoculated to the cultivation soil to reduce the bioavailability of Cd and Cr.
Characterization of microplastic pollution in Koggala lagoon and developing pollution risk indices
(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Mendis, C. C. D.; Wijeyaratne, W. M. D. N.; Narangoda, S. R. C. N. K.
Microplastic pollution is an emerging concern in both aquatic and terrestrial environments. The present study aimed to assess the abundance, diversity and environmental risk of microplastics (MPs) in the Koggala lagoon, Sri Lanka. Two sites were selected from the lagoon (Site A: lagoon river mouth; Site B: The mid region of the lagoon), and three replicates of water (100 mL for each replicate) and sediment samples (100 g for each replicate) were collected from each site over a six-month period, from August 2023 to January 2024. The number, colour, polymer and shape of MPs were analysed using standard analytical methods. The polymer type of microplastics were determined using FTIR spectrophotometry. The pollution risk indices (PRF - Potential Ecological Risk Factor, PLI - Pollution Load Index, and PHI - Polymer Hazard Index) were calculated for the two sites. The abundance of MPs between two sites was compared using Student’s t test. The mean microplastic abundance was significantly high, in both water and sediment, at the lagoon river mouth (water:0.17±0.04 MPs/cm3, sediment: 0.25±0.02 MPs/g; p<0.05) compared to the mid region of the lagoon (water: 0.12±0.01 MPs/cm3, sediment: 0.10±0.05 MPs/g; p<0.05). Microplastics of different colours (white, green, yellow, blue, red, black, pink and translucent), shapes (fibre, filament, fragment, and film), and polymer types (polyethylene, polypropylene, polystyrene, and ethylene propylene diene rubber) were identified from both study sites. Site A recorded significantly higher mean percentage of fibre (16.0±0.50) and filament-shaped microplastics (11.00±0.00), higher mean percentage of translucent (6.00±0.01) and yellow (7.50±0.02) coloured microplastics, higher mean percentage of polyethylene polymer type (63.00±0.01) and polystyrene polymer type (8.00±0.00) compared to the site B. Site B recorded significantly higher mean percentage fragment (52.00±0.00) and film- shaped microplastics (30.00±0.50), a higher mean percentage of green (39.50±0.01) coloured microplastics and higher mean percentage of polypropylene (39.00±0.02) and ethylene propylene diene rubber polymer types (12.00±0.00) compared to the site A. All three pollution risk indices considered in this study were highest in the site A (PRF= 2.155, PLI= 1.465, PHI= 927). The study area (Koggala lagoon) was classified as low risk (Category I) for microplastic pollution based on the Pollution Load Index (PLI) values. According to the PLI, Koggala lagoon can be categorized as Hazard Level 1. However, according to the PHI, Koggala lagoon shows significant danger for microplastic pollution based on polymer types.
Characterization of the water quality in the Rekawa lagoon, Sri Lanka
(Faculty of Science, University of Kelaniya Sri Lanka, 2024) De Silva, K. V. N. T.; Wijeyaratne, W. M. D. N.
Rekawa lagoon is located in the Hambantota district in the Southern province of Sri Lanka. The lagoon is of high ecological and socio economic significance and is heavily utilized for aquaculture and fisheries purposes. The present study was conducted to assess the pollution status of selected sites in Rekawa lagoon in terms of water quality indices. The data was collected from five sampling sites in the lagoon; Site A: canal mouth, Site B: adjacent to residential areas, Site C: adjacent to agricultural lands, Site D: adjacent to hotels and shrimp farms, Site E: adjacent to mangrove forests. The water samples from each sampling site were analysed monthly for a period of six months from August 2023 to January 2024 to measure the water pH, salinity, turbidity, conductivity, DO (Dissolved Oxygen), TDS (Total Dissolved Oxygen), BOD5(Biological Oxygen Demand), temperature and Cr, Cd, Pb concentrations taking 5 replicates for each sample. In-situ parameters such as pH, salinity, turbidity, conductivity, DO, TDS, temperature were measured using multiparameter. The BOD5 values were measured according to APHA 2017. Heavy metal concentrations were measured using GBC SavantAA. The spatial and temporal variation of water quality parameters were assessed using one – way ANOVA followed by Tukey’s pairwise comparison by Minitab 17 software. Water quality index (WQI) was calculated from the water quality data. The WQI reflects moderate confidence due to the absence of microbiological parameters. The results of the present study indicated significant spatial variations of temperature, salinity, EC (Electrical Conductivity), pH, DO, BOD5, Cr, Cd, Pb and Zn concentrations. The highest mean surface water temperature was recorded at site C (32.5±0.11oC), highest mean surface pH at site A (8.35±0.06), highest mean conductivity at site A (28.48±0.28 mS/cm), highest mean water salinity at site A (10.31±0.21‰), highest mean DO at site A (8.09±0.01 mg/L), highest mean BOD5 at site C (4.77±0.02 mg/L), highest mean chromium concentration at site D (1899.00±0.00 ppb), highest mean cadmium concentration at site D (10.01±0.00 ppb), highest mean lead concentration at site D (157.02±0.00 ppb) and highest mean zinc concentration at site D (281.00±0.00 ppb). Salinity, EC, pH and temperature showed significant temporal variations among the sites. The highest mean surface water temperature was recorded in August, October and November (32.5 oC), highest mean salinity in August (12.00 ‰), highest mean conductivity in November (28.80 mS/cm) and highest mean pH in August (8.11). The highest WQI was recorded at site D (51.8) while the lowest was recorded at site E (26.6). According to the WQI the site D was categorized as poor while the other sites were categorized as good. The high load of organic pollutants released by the hotels and restaurants in the vicinity was identified as a possible cause for the degradation of water quality at site D as many point source wastewater outlets were identified at this site. Therefore, it is recommended to conduct adequate water quality monitoring and management activities in the Rekawa lagoon to ensure the continuous ecological and economic benefits acquired from the lagoon and to prevent the possible degradation.
Chromosomal Abnormalities in Allium cepa Induced by Treated Textile Effluents: Spatial and Temporal Variations
(Journal of Toxicology, 2020) Wijeyaratne, W. M. D. N.; Wickramasinghe, P. G. M. U.
Appropriate effluent treatment processes are expected to significantly reduce the toxicity of effluents before they are released to the natural environment. 0e present study was aimed to assess the spatial and temporal variations of the physical and chemical water quality parameters of a natural water body receiving treated textile effluents and to assess the chromosomal abnormalities induced by the treated textile effluents. Four sampling sites (A: effluent discharge point; B: 100m downstream from site A along the tributary; C: 200m downstream from site A along the tributary; D: 100m upstream from site A along the tributary) were selected associated to a tributary that received treated textile effluent. 0e physical and chemical water quality parameters were measured in the composite water samples collected from the study sites, and Allium cepa bioassay was conducted using aged tap water as the control. Sampling was conducted in both rainy and dry seasons. 0e conductivity, TDS, COD, and colour intensity of the water samples collected from the study sites were significantly higher during the dry season compared to those in the rainy season. Allium cepa root meristematic cells exposed to water samples from sites A, B, and C showed a significantly high interphase and prophase indices compared to those exposed to aged tap water and upstream site during both rainy and dry seasons. 0e mitotic index of the root tip cells of Allium cepa bulbs exposed to the water samples collected from the effluent discharge point (site A) and from the 100m downstream site from site A (site B) was significantly lower than that of the other sites in both rainy and dry seasons. However, the mitotic index of the root tip cells of Allium cepa bulbs exposed to the water samples from the upstream site was not significantly different from that of the control treatment during both sampling seasons. 0e bioassay indicated that the mitotic index and phase index of the root meristematic cells of Allium cepa can be affected by the treated textile effluents released to the water body and the occurrence of C metaphase, chromosomal adherence, bridges, disturbed anaphase, vagrant chromosomes, and chromosomal breaks indicated that the treated textile effluent receiving tributary can possibly contain genotoxic and mutagenic compounds which can induce chromosomal abnormalities.
Cyanophyceans as bioindicators of water quality in the Diyawannawa wetland, Sri Lanka
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Nanayakkara, D. B. M.; Wijeyaratne, W. M. D. N.
Cyanophyceans, which is a group of phytoplankton, are important in maintaining the ecological balance in wetlands. The abundance of cyanophyceans is strongly influenced by environmental parameters. The objective of this study was to assess the abundance of cyanophyceans in relation to water quality and to identify possible bioindicator cyanophyceans in Diyawannawa wetland. Seven input streams to the Diyawannawa wetland were selected as study sites. At each site, pH, temperature, dissolved oxygen (DO), visibility, depth, salinity, conductivity, nitrate nitrogen (TN), dissolved phosphate (DP), total phosphate (TP), biochemical oxygen demand (BOD5), chlorophyll-a (Chl-a) and abundance and diversity of phytoplankton of family Cyanophyceae were identified from May to September 2018 following APHA standard methods. Spatial variation of water quality and abundance of cyanophyceans were assessed using one-way ANOVA followed by Tukey’s pairwise comparison. Pearson’s correlation analysis and regression analysis were performed to identify possible relationships among cyanophyceans and water quality of the wetland. MINITAB-14 was used for statistical analysis. Total of 19659 members of Cyanophyceae belonging to 13 species were recorded. Gloeocapsa sp, Merismopedia glauca, Microcystis aeruginosa, Microcystis incerta, Oscillatoria sp. and Spirulina sp. were present in all the sites and showed significant variations in their distribution. Anabaena sp. and Chroococcus limneticus were also present in all sites, but did not show significant differences of abundance. Significant variations of TN, DP, TP, salinity, conductivity, DO, visibility, BOD5 and Chl-a were recorded (p<0.05). Pearson’s correlation analysis was performed to assess the relationship between the abundance Cyanophyceans with water quality parameters. Spirulina sp. showed strong positive correlations with conductivity (r=0.981, p=0.000), salinity (r=0.995, p=0.000), TP (r=0.962, p=0.001) and DP (r=0.996, p=0.000). Oscillatoria sp. also showed strong positive correlations with salinity (r=0.992, p=0.000), conductivity (r=0.982, p = 0.000), TP (r=0.967, p=0.000) and DP (r=0.996, p=0.000). Further, both Spirulina sp. (r=0.763, p=0.046) and Oscillatoria sp. (r=0.759, p=0.048) showed strong negative correlations with TN. Linear regression analysis between the abundance of Spirulina sp. and Oscillatoria sp. with conductivity, salinity, TP, DP and TN indicted that abundance of both species are influenced by conductivity, salinity, TP and DP (R2>90%, p=0.000). The results of the present study suggest that there is a possibility of using Spirulina sp. and Oscillatoria sp. as biological indicators of high TP, DP, salinity and conductivity in the Diyawannawa wetland. It is recommended to conduct more biological assessments to determine the suitability of using these cyanophyceans as bioindicators in other wetlands in Sri Lanka.
Efficacy of Phyllanthus emblica bark powder in reducing total hardness of domestic well water in Jaffna peninsula, Sri Lanka
(Research Symposium on Pure and Applied Sciences, 2018 Faculty of Science, University of Kelaniya, Sri Lanka, 2018) Shanthamareen, M.; Wijeyaratne, W. M. D. N.
Jaffna peninsula is underlain by thick Miocene limestone deposits and these geological formations result in increased hardness of ground water. Increased hardness of drinking water can result in severe health effects including higher risk for urinary and salivary stone formation, urolithiasis and chronic kidney disease. The present study was conducted to evaluate the potential of the Phyllanthus emblica bark powder to be used as a home remedial method to reduce total hardness of drinking water. Water samples with three replicates were collected from 15 domestic wells from Kondavil area, Jaffna peninsula. The total hardness (TH), pH, temperature, Dissolved Oxygen (DO), Electrical Conductivity (EC), salinity, nitrate-N and Total Phosphorous (TP) concentration of these water samples were measured using standard methods (APHA). The water quality parameters were compared with the Sri Lanka Standards Institution (SLSI) drinking water standards . The pH and TP concentration of wells were within the SLSI drinking water standards. However, all the tested wells exceeded the total hardness concentration (250 mg/L) and 60% of the wells exceeded total nitrate (11.3 mg/L) concentrations established by SLSI for safe drinking water. The mean TH of the wells ranged from 454.8 to 784.4 mg/L CaCO3 and the mean nitrate-N ranged from 0.82 - 20.99 mg/L respectively. Well water samples were then filtered in a column filter using Phyllanthus emblica bark powder and the total hardness and total nitrate of the filtered water samples were measured . The variation of these parameters before and after filtration were compared by paired t test using MINITAB 14 software . After filtration through the Phyllanthus emblica bark powder, a significant reduction (paired t-test, p<0.05) of TH was observed with a 9 . 50% reduction . However, filtration through Phyllanthus emblica bark powder increased the nitrate concentration (4.89%). Therefore, it was concluded that Phyllanthus emblica bark powder could be used as a remedial method to reduce hardness in drinking water .
Efficacy of Terminalia arjuna mature leaf powder and Phyllanthus emblica bark powder to reduce nitrate: N and total hardness in groundwater in karstified limestone aquifer
(Applied Water Science, 2020) Wijeyaratne, W. M. D. N.; Shanthamareen, M.
Groundwater is a vital resource in the northern region of Sri Lanka, as it is the only water resource used for domestic, agricultural and industrial activities in that area. However, due to excessive usage of synthetic fertilizer, the groundwater in this part of the country is highly contaminated with nitrates. In addition, due to the effect of underlain limestone aquifer, water hardness is also high. The present study aimed to study the effect of filtration through Terminalia arjuna mature leaf powder and Phyllanthus emblica bark powder on reducing nitrate concentration and hardness. The results indicated that 21.4% reduction of nitrate concentration can be achieved by filtration through Terminalia arjuna mature leaf powder and 9.3% reduction of total hardness by filtration through Phyllanthus emblica bark powder. Therefore, further research is recommended on testing the potential and side effects of using Terminalia arjuna mature leaf powder and Phyllanthus emblica bark powder as a combined home remedial treatment technique for treating nitrate contaminated hard water.
In depth analysis of groundwater quality and use of Moringa oleifera leaf powder treatment to improve physico-chemical properties and drinkability of contaminated groundwater
(Environmental Nanotechnology, Monitoring & Management, 2019) Wijeyaratne, W. M. D. N.; Suvendran, S.
Groundwater is the major source for domestic, and other uses in the Jaffna Peninsula, Sri Lanka. This study assessed the spatial and seasonal variation of physical and chemical parameters of water collected from domestic wells in Chunnakam and Vadamaradchi aquifers. The measured physicochemical parameters were compared with the drinking water standards established by Sri Lanka Standards Institution. Significant spatial variations in the water quality parameters were identified in both areas. Significantly elevated levels of nitrate and oil & grease were identified in Chunnakam, whereas significantly elevated levels of DO and pH were recorded in Vadamaradchi. Nitrate concentration of the wells ranged between 0.021–40.1 mg/ L. Oil & grease of these wells ranged from 0.011 to 0.373 mg/L. In Chunnakam, 60% of sampled wells had nitrate level above the permitted nitrate standard level, and all the wells had elevated oil and grease concentration above the permitted standard limit. Filtration of water through Moringa oleifera leaf powder could significantly reduce the nitrate an oil and grease concentrations, thereby improving the quality of water.
Macrophytes as indicators of the ecological status of a tropical rehabilitated wetland ecosystem: Application of multivariate statistics and Ecological State Macrophyte Index (ESMI)
(Int. J. Aquat. Biol., 2020) Wijeyaratne, W. M. D. N.; Bellanthudawa, Aravinda
The present study used the Ecological State Macrophyte Index (ESMI) and the multivariate statistical methods to assess the ecological status and the variation of macrophytes in a tropical wetland system. Six sites were selected from rehabilitated and non-rehabilitated areas of an urban tropical wetland and the water quality parameters (water pH, temperature, conductivity, total dissolved solids (TDS), dissolved oxygen (DO), visibility, biological oxygen demand 5 days after incubation (BOD5), chemical oxygen demand (COD), nitrate, chlorophyll-a and total phosphorus concentrations), sediment quality parameters (pH, organic matter content, percentage sand, silt and clay content) and abundance of aquatic macrophytes were measured. Shannon Weiner diversity index, percentage vegetation under anthropo-pressure, macrophyte settlement rate and ESMI were calculated. Significant variations in the water and sediment quality parameters were observed and ten species of aquatic macrophytes were recorded. Salvinia melosta and Cypreus iria were recorded only from the non-rehabilitated sites. Although there was no significant difference in the percentage anthropo-pressure among study sites, the rehabilitated sites were displayed low anthropo-pressure. The sites in the non-rehabilitated area showed a significantly lower macrophyte settlement rate. ESMI and macrophyte abundance showed significant correlations with water quality parameters. Based on the results, it can be recommended that applications based on ESMI and multivariate statistics can be used to assess the ecological status of tropical wetlands.
Studying the behaviour of export quantities of Tuna fish in Sri Lanka
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Sachithra, S. A. L.; Liyanage, U. P.; Wijeyaratne, W. M. D. N.
Being an island in the Indian Ocean, Sri Lanka claims a large sea area and abundant fish resource with high facilitate suitable for large scale fishery industry. According to the Central Bank of Sri Lanka, the contribution of fisheries to the Gross Domestic Production (GDP) of the country ranges between 1.3% and 1.6%. Consequently, fishery industry already plays a vital role in economics and social development of Sri Lanka. Due to weather conditions, seasonal effects, changes of government tax policies and trade agreements, e.g. GSP+ and etc., there is a high fluctuation in export quantity of fishery products in Sri Lanka. Thereby, it is essential to study the variation patterns and forecast harvest and income generated by fishery products towards monitory strategy planning. Among the various types of fish, tuna is one of the species that is important in financial earnings. Out of all fisheries exports, Sri Lanka earns the highest income worth 50.8% by exporting tuna fish in 2016, according to the statistics from Ministry of Fisheries and Aquatic Development of Sri Lanka (SLMFAD). This study was conducted to analyze the export quantities of tuna fish and forecast the future export quantities. Monthly export quantities from January, 2010 to June, 2018 were collected from SLMFAD. In preliminary analysis, United States, Japan, and Canada are identified as the top countries in which Sri Lanka exports the highest quantity of tuna fish. To study the changes in export patterns and their associated relations, Statistical Change-Point Analysis was conducted. The results revealed a high correlation between the changes of export patterns with events such as country’s peace restoration, economic stability, infrastructure facilities, introduction of different capacity changes and termination of development projects. Towards forecasting the export patterns time series data analysis techniques were used. Unit root tests; Augmented-Dickey-Fuller Test (ADF) and Kwiatkowski-Phillips-Schmidt-Shin test (KPSS) were used to test the stationarity of the time series data. Based on Akaike information criterion (AIC) value, SARIMA (1,1,2)(1,0,0)12 model was identified as the best. Ljung-Box test, Jarque-Bera test and Heteroscedasticsity test were used to check the behavior of the residuals of this fitted models. Accuracy of the models were compared by root mean squared error (RMSE), and mean squared error (MSE). With 0.8485 of RMSE and 0.6038 of MSE, SARIMA (1,1,2)(1,0,0)12 model can be considered as the most suitable model to forecast the export tuna quantity from Sri Lanka.