ICAPS 2023

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Spatial distribution of soil and water quality in Eldeniya - East grama niladhari division
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Deraniyagala, P. E. P. S.; Heenkenda, H. M. D. S. D.; De Silva, R. C. L.
Water is becoming a consequential part of the daily life of humans. Therefore, mapping of soil and water quality parameters is required for regular monitoring of them to provide the necessary evidence to make decisions on managing water and soil quality today and in the future. Furthermore, mapping soil and water quality parameters is necessary for environmental monitoring, agricultural management, land use planning, water resource management, and conservation efforts. This research analyzes soil and water quality parameters in the EldeniyaEast grama niladhari division, Gampaha district. Fifty-six samples of soil and water were collected from the selected area. Water quality parameters pH, conductivity, nitrate content, phosphate content, and hardness were analyzed, and soil quality parameters pH, nitrate content, soil organic matter content, Na+, K+, and Ca2+ content in the soil were analyzed. Then their spatial distribution was represented as contour maps. pH was analyzed using a pH meter and the pH of water samples lies between 3.79 – 7.18. Except for one, all the other water samples gave acidic pH. Suggesting that Eldeniya-East has almost all acidic water sources. The conductivity of water samples was measured using a conductivity meter and the obtained values lie between 54.0 µS/cm – 403.0 µS/cm. All the samples gave extremely low conductivity values. Water-soluble phosphate was not detected in the water samples. This suggests that water sources within this area are not contaminated with excessive amounts of phosphates. Nitrate content was measured using an ionselective nitrate electrode and the obtained values lie between 59.5 ppm to 168.0 ppm. According to EPA, this area's water sources have nitrate contents higher than the safe levels for drinking water. The calcium hardness of water samples lies between 0.00 – 59.92 mg CaCO3/L, and Mg2+ was not detected. According to Sawyer and McCart's classification, all water samples are categorized as soft water. The pH of the soil samples lies between 3.07 – 6.68 where all are acidic pH values. Considering obtained soil and water pH values, it can be said that the study area has a considerable acidic nature. Nitrate content in soil samples lies between 52.2 – 217.0 ppm and a linear relationship exists between soil nitrate content and the water nitrate content. SOM of soil samples was measured using the Walkley–black method, and SOM lies between 0.000 – 12.930 %. According to the results, this area contains water-soluble calcium in a range of 0 - 2 mg/L, water-soluble sodium in a range of 6 - 18 mg/L, extractable sodium in a range of 1 - 56 mg/L, water-soluble potassium in a range of 1 - 12 mg/L and extractable potassium in a range of 9 – 108 mg/L. This analysis, which has been conducted as a pilot project covering only one grama niladari division can be further extended to map the entire country which then can be used for the continuous investigation of soil and water quality parameters.
Investigation of antioxidant and antityrosinase activities of Premna serratifolia
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Katpaharajah, G.; Weerasiri, K. C.
In recent times, cancer and hyperpigmentation have been the most problematic issues faced by the people. As cancer is caused mostly by the free radicals in the body, antioxidants, which are radical scavengers, may reduce the mutations in the body. Hyperpigmentation is reduced by the compounds inhibiting the tyrosinase enzyme’s activity. So, the compounds responsible for antioxidant and antityrosinase activities are analysed. Many harmless bioactive compounds responsible for many bioactivities are present naturally in plants. For this research work, the Sri Lankan species Premna serratifolia was chosen as the focal subject with specific attention to its leaves, traditionally employed for alleviating ingestion related issues. Considering the absence of prior research on this plant in previous studies, the leaves and twigs were chosen to determine the antioxidant and antityrosinase activities. The leaves were extracted by maceration process (cold extraction) through a sequential extraction using hexane, ethyl acetate and methanol. The twigs were extracted using the Soxhlet apparatus (hot extraction) through a sequential extraction using ethyl acetate and methanol. The antityrosinase activity was determined by the tyrosinase enzyme’s catalytic reactions. The methanol extracts of leaves and twigs show higher antityrosinase activity (the IC50 value of leaves is 6.83 ± 1.31 mg/mL and the IC50 value of twigs is 8.20 ± 5.54 mg/mL) than their respective ethyl acetate extracts (IC50 value of leaves is 87.06 ± 54.90 mg/mL and IC50 value of twigs is 168.82 ± 2.60 mg/mL). The methanol extracts of leaves and twigs show similar antityrosinase activity within the concentration range of 0.200 – 1.600 mg/mL. At a concentration of 0.025 mg/mL, the methanol extracts of leaves and the twigs show higher antityrosinase activity than the standard Kojic acid yet, the twigs show more than the leaves. In ethyl acetate extracts, at a concentration of 0.025 mg/mL, twigs show higher antityrosinase activity than the standard Kojic acid and the leaves. The DPPH-radical scavenging method was employed to determine the antioxidant activity. The EC50 values of ethyl acetate extracts of leaves and twigs are higher (2.63 ± 1.61 mg/mL and 3.89 ± 1.57 mg/mL, respectively) than their respective methanol extracts (1.21 ± 0.64 mg/mL and 1.10 ± 0.65 mg/mL). Despite the methanol extracts having lower EC50 values, indicating high potent antioxidant activity, the ethyl acetate extracts of leaves and twigs exhibit higher antioxidant activity within the concentration range of 0.025 – 0.800 mg/mL. In ethyl acetate extracts of leaves and twigs, at a concentration of 0.025 mg/mL, the leaves show highest antioxidant activity than the twigs, but the twigs show higher antioxidant activity than the leaves within the concentration range of 0.100 - 0.200 mg/mL
Assessment of level of public knowledge, attitude, and perception towards sustainable mangrove forest conservation: a case study from Negombo region, Sri Lanka
(Assessment of level of public knowledge, attitude, and perception towards sustainable mangrove forest conservation: a case study from Negombo region, Sri Lanka, 2023) Wickramasingha, W. S. B.; Perera, W. W. A. M. R.; Kodithuwakku, K. C.; De Silva, K. V. N. T.; Karunarathne, D. M. S. D.
Mangroves have been an essential vegetative component not only in sustaining the balance of ecosystems but also in providing significant socio-economic benefits to the local communities such as fish, timber, and tourism opportunities to the local communities. Quantifying knowledge, attitudes, and perception (KAP) supports sustainable mangrove conservation by informing conservation efforts to address local needs and priorities and monitoring interventions' effectiveness over time. Thus, this study aims to determine the level of knowledge, attitudes, and perceptions of the public toward sustainable mangrove forest conservation in the Negombo region, Sri Lanka. Prior to data collection, a pilot study was conducted in the study area with 40 respondents and Cronbach's alpha (α = 0.819) reliability test was followed to test the reliability of the data. Data were collected via face-to-face interviews with randomly selected 395 respondents living near and around the northern region of the Negombo lagoon, which involved 8 Grama Niladhari Divisions. 51.39% of the individuals were male, while the remaining 48.61% were female, reflecting a commitment to gender equality. A Likert scale and correlation analyses were implemented using SPSS version 26 software to determine the community's knowledge, attitude, and perception (1-lowest and 5-highest). The finding shows that the level of knowledge of the community on the importance of sustaining mangrove forests was high from 3.92 to 4.72, the level of attitude was between 3.2 to 4.88, and the perception components from 4.47 to 4.83. There were significant gender differences in both attitude and perception toward mangrove forest conservation, with the female respondents achieving better scores than the male respondents, although there was no significant difference in their knowledge levels. Also, about 96.2% of respondents agree that the loss of mangroves will have negative impacts on the environment and the economics of the livelihood. Furthermore, most respondents believed that chemical pollution, illegal clearing, and development activities have a significant impact on the degradation of mangroves in the area. The correlation test showed that there was a strong positive correlation between knowledge and attitude (r = 0.901, p < 0.001), knowledge and perception (r = 0.795, p <0.001), and attitude and perception (r = 0.864, p < 0.001) respectively. They suggest that the most effective approach for preserving this ecosystem's survival is to engage in mangrove replanting through proper scientific monitoring, while also recommending the rectification of policy deficiencies and the execution of comprehensive strategies for mangrove conservation. The findings from this study may provide valuable information for future research, as well as assist government and stakeholders in enhancing the effectiveness of campaigns and programs focused on the sustainable management of mangrove forests.
Ionic conductivity of novel solid polymer electrolyte based on polyethylene oxide (PEO) and magnesium pyrophosphate (Mg2P2O7)
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Lakshan, K. L. A. C.; Sumathipala, H. H.; Wijesundara, L. B. D. R. P.
Lithium-ion batteries were hailed as a breakthrough solution for energy storage, revolutionizing portable electronics, electric vehicles, and other applications. However, as their implementation expanded, certain drawbacks came to light. Issues such as limited energy density, safety concerns, and the scarcity and high cost of lithium resources highlighted the need for a replacement. Researchers turned their attention to alternative materials, with sodium being a promising candidate due to its abundance. However, its high reactivity posed significant challenges. The search for a viable alternative led scientists to explore magnesium-based electrolytes. Lithium and magnesium are almost similar in ionic radii, presenting an exciting opportunity for further research. In this Investigation, the focus was on synthesizing and characterizing a novel magnesium ionbased solid polymer electrolyte. Polyethene oxide (PEO) was chosen as the polymer host, and magnesium pyrophosphate (Mg2P2O7) as the dopant salt. By varying the amount of salt while keeping the same amount of PEO, five different types of electrolytes were made: PEO5Mg2P2O7, PEO10Mg2P2O7, PEO15Mg2P2O7, PEO20Mg2P2O7, and PEO25Mg2P2O7. The hot-pressed technique was used to fabricate the solid polymer electrolytes, and the resulting materials were characterized in the frequency range of 1Hz to 1 MHz using the Gamry framework version 6.11. Arrhenius plots were derived from Nyquist plots to study the conductivity variation with temperature. The temperature range for the study spanned from 25°C to 100°C. The characterization results revealed that among the different electrolyte samples, PEO10Mg2P2O7 demonstrated the highest electrical conductivity of 5.0×10-6 Scm-1 at 50°C. This temperature was selected since the melting point of PEO is 64 °C. This value of conductivity is comparatively lower than most existing magnesium ion-based solid polymer electrolytes. The results from this study pave the way for further investigations and improvements. Incorporating fillers could enhance the conductivity of the electrolyte material and improve its overall performance. Such advancements may yield even more promising results, making magnesium-based solid polymer electrolytes viable candidates for solid-state batteries. Alternatively, a gel polymer might give a more promising result than a solid polymer.
Effects of a commercial probiotic incorporated feed on growth performance and nutrient digestibility of fancy guppy, Poecilia reticulata (Poecilidae)
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Dissanayake, D. S.; Epa, U. P. K.; Kumara, K. R. P. S.
The ornamental fish industry is one of the most thriving industries worldwide. The incorporation of probiotics into the feeds to enhance the production performance of cultured aquatic organisms is a novel implementation of science and technology. The present study was conducted to investigate the effects of a commercial probiotic incorporated feed on the growth performance and nutrient digestibility of Poecilia reticulata. Three experimental diets (T1- 1.0 x 10-1 cfu/mL, T2- 1.0 x 102 cfu/mL, and T3- 1.0 x 105 cfu/mL of probiotic concentration with four strains of Bacillus subtilis and a control diet (without the probiotic) were fed to fish in three replication glass tanks (30 cm x 15 cm x 30 cm) for 75 days. In each tank, ten P. reticulata with weight and length of 0.09 ± 0.00 g and 0.9 ± 0.00 cm respectively, were stocked after one week of acclimatization. Fish were fed twice a day at 2% of their body weight. Dissolved oxygen (DO) and pH were measured weekly and the standard length and weight of fish were measured biweekly. Fecal matter was collected twice a week from each experimental tank. The nutrient digestibility of P. reticulata was determined using chromic oxide as an inert marker. The proximate composition of the diets was analyzed using standard methods. DO and pH were not significantly different between the treatment and the control tanks (p>0.05, One-way ANOVA) and were within the optimum ranges for guppy (DO> 6 mg/L, pH 6.8- 7.8). Incorporating the probiotic into the commercial feed positively affected the specific growth rate (SGR), average daily growth (ADG), % body weight increase (% BWI), and % total length gain (% TLG) of P. reticulata. T3 had the best growth performance with the highest final weight (3.25± 0.78 g), length (2.6 ± 0.06 cm), %SGR (1.69 ± 0.31), ADG (0.03 ± 0.01 g/day) and % BWI (71.28 ± 6.25). The lowest final weight (2.084 ± 0.22 g), length (1.8 ± 0.15 cm), % SGR (1.15 ± 0.14), ADG (0.02 ± 0.00 g/day), % BWI (56.51 ± 4.30) were recorded in the fish fed the control diet. All the growth parameters were significantly higher in the T1, T2 and T3 than in the control (p>0.05, One-way ANOVA). There was no significant difference in the nutrient digestibility of P. reticulata between each treatment and the control (p>0.05; One-way ANOVA). Further, the proximate analysis showed no significant difference in the crude protein and ash content among the different experimental feeds (p>0.05; One-way ANOVA). The commercial probiotic used in the study did not affect the nutrient digestibility of P. reticulata, water quality in rearing tanks or proximate composition of experimental feeds. The incorporation of a commercial probiotic into the diet of P. reticulata significantly increased its growth performance.
Preliminary study of antioxidant and anti-inflammatory properties of mistletoe (Dendrophthoe falcata) on mango host plant (Mangifera indica).
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Raseena, M. T. F.; Kadigamuwa, C. C.
Dendrophthoe falcata is a common mistletoe plant that has widespread use in Sri Lankan traditional medicines. With the escalating incidence of cancer, asthma, and chronic inflammatory ailments among patients, the exploration of natural remedies in developing nations has become increasingly important. Despite existing research focusing on the chemical composition and biological activities of mistletoe plants in general, a critical gap exists in understanding the specific anti-inflammatory and antioxidant properties of Dendrophthoe falcata when it thrives on its particular host, Mangifera indica. This preliminary study aims to investigate the antioxidant and anti-inflammatory properties of mistletoe, Dendrophthoe falcata leaves grown on the host, Mangifera indica in Sri Lanka. The methanolic extracts of Dendrophthoe falcata and Mangifera indica leaf samples were prepared using the cold extraction method. The antioxidant activity was assessed through the Folin-Ciocalteu assay, ammonium colourimetric method, 2,2- diphenylpicrylhydrazyl (DPPH) assay, and ferric-reducing power assays. Anti-inflammatory action was evaluated using heat-induced hemolysis and albumin denaturation assays. Pearson’s correlation test was performed to determine whether there is a linear relationship between total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity, antiinflammatory properties of Dendrophthoe falcata and Mangifera indica. A two-sample t-test was done to compare the results of TPC and anti-inflammatory and antioxidant properties of Dendrophthoe falcata and Mangifera indica to identify whether these values of mistletoe significantly vary from the host. TPC and TFC of mistletoe were determined to be 1531.0 ± 44.3 mg of gallic acid equivalents per g of extract and 210.7 ± 15.9 mg of catechin equivalents per g of extract through Folin-Ciocalteu assay, ammonium colourimetric method respectively. Mistletoe exhibited an IC50 of 239.70 ± 27.99 µg/mL for DPPH scavenging activity and an EC50 of 6921.0 ± 2419.0 µg/mL for ferric-reducing power. Additionally, mistletoe demonstrated an IC50 of 554.1 ± 42.4 µg/mL for antihemolytic activity and 0.45 ± 0.05 mg/mL for protection against albumin denaturation. Pearson’s correlation analysis revealed that phenols contribute to antioxidant activities. Furthermore, the presence of phenols and flavonoids contributed to the antiinflammatory properties. A t-test comparison between mistletoe and its host plant for bioactive compounds, antioxidants, and anti-inflammatory properties indicated that mistletoe’s bioactive compounds and their antioxidant and anti-inflammatory properties are significantly different from host plants. Dendrophthoe falcata leaves emerge as a promising source of anti-inflammatory and antioxidant properties. This avenue of study bears substantial potential for unlocking novel therapeutic benefits and can be further pursued by determining the chemical structure of the specific bioactive compounds responsible for anti-inflammatory and antioxidant properties.
Microplastics in selected offshore pelagic fish in Indian Ocean
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Jayarathna, N. K. D. M. P.; Walpita, C. N.; Amarathunga, A. A. D.; De Silva, D. S. M.; Sivyer, D. B.
Microplastics (MPs) pollution in marine environment is an emerging threat to marine biota. Marine pelagic fish species such as tuna and tuna-like species caught during offshore fisheries in open seas, are known to be more commercially important and could be contaminated by MPs. As such, MPs could pose a risk to fish by themselves and to human health due to consumption of contaminated seafood. The present study was planned to investigate the MPs contamination of commercially important three pelagic fish species (Thunnus albacares, Katsuwonus pelamis, and Elagatis bipinnulata) caught from offshore fisheries using multiday boats from several locations of the Indian Ocean to fill the knowledge gap on MPs contamination of pelagic fish, especially in the Indian Ocean. Fish samples were collected from Beruwala, Galle, Panadura and Negombo fishery harbors in Sri Lanka, and the gastrointestinal tract (GIT) and gills were examined for possible MP contamination. A total of 40 samples belonging to three fish species were used for the study. The abundance and morphology (i.e. color, shape) of the MPs were assessed, and the polymer type of the MPs was investigated by using ATR-FTIR. Descriptive analysis was done by using IBM SPSS statistical version 26 and MS excel was used to calculate the percentages of MPs by color, shape and polymer type. There was a contamination of MPs in all three fish species. Nevertheless, 12.5% of E. bipinnulata and 21.7% of K. pelamis did not show MPs in analyzed tissues. T. albacares was found to have the greatest number of MPs (15±6 items individual-1). The morphology of the MPs found from the GIT and gills of all the three fish species were fibers (51%), followed by fragments (37%) and films (12%). In GIT, the most prominent color was blue in all the fish species. Moreover, the polymer types found belonged to three categories viz, thermoplastic elastomers (TPE), phenol formaldehyde resin (PF), and polyethylene copolymer (PE-Copolymer). Among them, the most prominent type of polymer was PF. PE-copolymer was found only in T. albacares. Therefore, continuous monitoring of marine environment and implementing stringent regulations are recommended to minimize plastic pollution in the Indian Ocean to protect both the marine ecosystem and humans.
Development of a cost-effective real-time commuter counting system for public transportation in Sri Lanka
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Premasiri, R. H. M. D.; Koralage, K. G. S. D.; Hasaranga, J. P. K.; Alawaththa, A. K. N. A.; Seneviratne, J. A.; Ranaweera, A. L. A. K.
The use of smart systems in public transportation is relatively new in the Sri Lankan context. This study introduces a cost-effective solution for accurately counting the number of bus passengers at any given time. Current passenger counting systems in Sri Lanka often suffer from inaccuracies and inefficiencies, hindering the effective management of public transportation and addressing problems including long bus queues, ticketing fraud, long waiting times, etc. Precise passenger count is essential for optimising services and resources, ultimately enhancing the efficiency of public transportation in the country. The proposed system is designed to be installed in buses and includes an online platform where users can enter the bus number and check the passenger occupancy in real-time. The proposed system comprises several key components: two input sensors, a microcontroller, a wireless connectivity module, an in-built display, an input panel, and an output display. The two sharp IR sensor modules employed as input sensors are connected to a microcontroller. An inbuilt display connected to the microcontroller provides output information, including passenger count, number of vacant seats, GPS signal strength, and data transmitting capability. Data is wirelessly sent to a cloud database for storage, retrieval, and processing, enabling users to access relevant information via a web application. The algorithm employed in this system ensures precise passenger count by detecting specific sequences of readings from the two IR sensors. To increment the passenger count, the system requires the following sequence: "0-0, 1-0, 1-1, 0-1, 0-0." This sequence corresponds to the detection of a passenger boarding the bus. Each step in the sequence represents the state of the two IR sensors, with "0" indicating no obstacle and "1" indicating an obstacle (i.e., the presence of a passenger). The algorithm recognizes this sequence as an entry event and increments the passenger count accordingly. Conversely, the algorithm relies on the following sequence to accurately decrease the passenger count when a passenger exits the bus: "0-0, 0-1, 1-1, 1-0, 0-0." This sequence represents a passenger leaving the bus. The algorithm reduces the passenger count by monitoring the sensor readings and identifying this sequence. These specific sequences in the algorithm ensure reliable and accurate passenger counting. By requiring a particular order of sensor readings, false positives or negatives caused by noise or temporary obstacles are minimised, leading to a more precise passenger count. The online platform allows users to access passenger occupancy in a particular bus, which aids in real-time service optimization for public transportation management. The system achieves precise real-time passenger occupancy tracking using two Sharp IR sensors and a finely tuned algorithm. Tested results of the pilot system show that data empowered public transportation management in Sri Lanka by optimising routes, efficiently allocating resources, and significantly improving the overall commuter experience. In conclusion, the combination of affordability, reliability, and user-friendliness makes this proposed solution suitable for efficiently managing public transportation systems.
Pueraria phaseoloides and Croton laccifer as sources for green manure formulations in Sri Lanka
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Gammudaly, H. M.; Ratnatilleke, A. A. L.
One of the critical problems that Sri Lanka is facing today is the inorganic fertilizer problem, which has severely affected the economy and agriculture in the country. For this crisis, a potential and a profitable solution can be obtained using local green manures. Green manures are the plants that are incorporated into the soil while still green. They facilitate the plant growth by enhancing the soil health and fertility. In Sri Lanka, several plant species, Gliricidia sepium, Pora wel (Pueraria phaseoloides), Kappetiya (Croton laccifer L.), Ipil ipil (Leucaena leucocephala) and Gansooriya (Thespesia populnea) are used as green manures since the past. This study evaluated the effectiveness of Pueraria phaseoloides and Croton laccifer L. as local green manures. In this research, experiments have been done on total nitrogen content, nitrogen release into the soil, impact of green manure on a selected plant growth (Capsicum annuum) and changes in soil parameters after the application of green manure. For the determination of nitrogen amount, the Kjeldahl method and Ion selective nitrate probe were used. Results indicated that Pueraria phaseoloides leaves contained the highest amount of nitrogen as ammonium nitrogen (0.63%), while its stems contained the highest amount of nitrogen as nitrate nitrogen (0.11%). Similar observations were also made with Croton laccifer, where its leaves showed the highest amount of nitrogen as ammonium nitrogen (3.05%). Nitrogen release experiments showed that the nitrogen levels in soil increased over the time after the incorporation of plant materials. Incorporation of Pueraria phaseoloides, into soil increased the ammonium nitrogen percentage from 0.11% to 0.7% and the nitrate percentage in soil was increased from 0.005% to 0.09%. Similarly, incorporation of Croton laccifer into soil increased ammonium nitrogen percentage from 0.11% to 0.92%. In the growth experiment, Pueraria phaseoloides and Croton laccifer plant materials were incorporated into soil, in pots, where chilli was used as the test plant. Results showed a 49.1% and 43.4% increase in height for Pueraria and Croton, respectively and a significant difference in plant height (P < 0.001) when compared to the control. Furthermore, the water holding capacity of soil was tested to study the changes of soil parameters after the incorporation of green manure. The results indicated that there was a significant increase, 20.9% and 16.5% for Pueraria and Croton, respectively in the water holding capacity of soil with and without the incorporation of Pueraria phaseoloides and Croton laccifer plant materials. The overall results indicated that Pueraria phaseoloides and Croton laccifer can be used as a potential solution for the fertilizer problem.
A complex sample design based analysis of determinants of secondary job holding of heads of households in Sri Lanka
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Pannala, P. A. H. S.; Deshani, K. A. D.
Heads of Households (HHs’) play the most prominent role in families. This study was mainly focused on HHs’ who were engaged in secondary jobs (SJ) in Sri Lanka. Exploring methods and techniques of incorporating complex sample design into analysis and identifying factors associated with secondary job enrolment of HHs’ in Sri Lanka by developing a statistical model using complex sample design were main objectives of the study. The data of the Annual Labour Force Survey-2019 was collected from the Department of Census & Statistics. The sampling method of the survey was two-stage stratified. A sample where sampling method was not simple random sampling is called a complex sample. The study emphasized that analysing and modelling techniques developed for simple random samples could not be used for data from a complex sample. Thus, study used descriptive, univariate, bi-variate analysis techniques developed for complex sample data. Since both sample design and weights were used analysis is design-based. Complex sample binary logistic regression modelling techniques were used to acquire the status “being secondary employed or not”. High class imbalances were noticed, and over-sampling, under- sampling, and SMOTE techniques were tried, and under-sampling was selected as the best way of balancing the data. Two models were developed, for the original data and for the under-sampled data. Nagelkerke R square and classification table were considered to compare the overall fit of two models. The overall accuracy of models developed for original and under sampled data given by classification table was 90.4% and 71.2% respectively. But class-wise accuracy was high in model fitted for balanced data set with under-sampling. Model developed for original data correctly predicts only 0.8% of SJ enrolment of HHs’ and 99.9% correctly non-SJ enrolment while model fitted for balanced data correctly predict 41.1% of the SJ enrolment of HHs’ and 86.9% non-secondary job enrolment. Model developed with interaction terms for the balanced data set had overall accuracy 74.1% which is not a considerable improvement compared to main effects model for the same dataset with 71.2% overall accuracy and, consisted of more predictor variables again led to choose main effect model. According to the model derived for the balanced data, being in rural sector, being male, engaging in occupations managers, senior officials and legislators, professionals, services and sales workers, skilled agricultural, forestry and fishery workers, monthly income below rs.15,000.00, increased the likelihood of being a secondary employed HH. Moreover, no published work could be found on a design-based analysis on this topic. Thus, study leads the government and employers to find out determinants of SJ holding of employed HHs’ and to adjust their plans and improve the quality of primary and SJs.
Assessment of contaminant levels of hazardous toxic metals and subsequent risk analysis in agricultural soil and selected comestibles within a region afflicted by CKDu in Sri Lanka
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Perera, M. A. S. N.; Kadigamuwa, C. C.; Gunathilaka, V. H. N. M.; Samaraweera, G. A.; Perera, W. P. R. T.; Perera, P. L. R. A.; Liyanage, J. A.; Premaratne, W. A. P. J.
Agricultural commodities constitute a pivotal component of the human daily sustenance, yet they are susceptible to contamination by pernicious heavy metals, notably Hg, Cd, Pb, and As. Consequently, agricultural products represent a substantive source of apprehension for human well-being and health. This study aims to evaluate related risk indices of agricultural soils (n=25) and selected comestible grains, namely Oryza sativa (n=25), Vigna radiata (n=25), Vigna unguiculata (n=25), and Vigna unguiculata subsp. (n=25), within the endemic region of Nikawewa Grama Niladhari Division (GND) in North Western Province (NWP) and the reference region, Wewagedara GND in NWP where no evidence for Chronic Kidney Disease of unknown etiology (CKDu). The concentrations of metals in the collected samples were determined by using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and based on that risk indices were calculated. The mean geo-accumulation index (Igeo) for four metals in soil was As - 0.82, Cd - 1.47, Cu - 0.91, and Pb 1.31. That indicates no anthropogenic activities related to As, Cd and Cu while Pb is responsible for moderate pollution in endemic area. Estimated Daily Intake (EDI) values for these heavy metals were calculated with respect to the all grains. EDI means of As and Pb in the endemic and the reference areas for all grain samples were within the Tolerable Daily Intake (TDI) set by United States Environmental Protection Agency (USEPA) (As-0.300 􀁐g/kg/day) and World Health Organization (WHO) (Pb-3.600 􀁐g/kg/day) while Cd (EDI in endemic area; Oryza sativa-6.385 􀁐g/kg/day, Vigna unguiculata-3.386 􀁐g/kg/day and Vigna unguiculata subsp.-3.866 􀁐g/kg/day) highly exceeded the tolerable weekly intake (TWI) of European Food Safety Authority (EFSA) (Cd-2.5 􀁐g/kg/week) in both areas. EDI of Cr in rice samples (1.138 􀁐g/kg/day) in endemic area exceeded the TDI set by EFSA (1.0 􀁐g/kg/day) and all other values of Cr were below the TDI in both areas. According to the USEPA (intolerable cancer risk (CR) - > 1 x 10-4) cancer risk exist for all these staple grains. Igeo of Pb in the soil, raising concerns about their bioavailability and uptake by the food crops and EDI were indicated the long-term consumption of these foods especially Oryza sativa poses a serious threat to human health. Implementing proper soil management practices, monitoring heavy metal levels in crops, and raising public awareness about safe consumption practices are crucial steps towards mitigating the risk of CKDu.
Preliminary studies of antioxidant and anti-inflammatory activities in methanol extracts of mistletoe (Pilila) in guava
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Tharakee, D. H.; Kadigamuwa, C. C.
Animal welfare receives great attention as it is highly important for enhancing milk production and microbiological quality. Literature reveals that the apprehension of dairy cow welfare practices among farmers is at a low level and limited studies have been carried out on dairy cattle welfare, in Sri Lanka. This study focused on investigating the impact of cattle management and welfare practices on the microbiological quality of raw milk. A total of 87 dairy cows from 50 tie-stall dairy farms in the Naththandiya Area in Sri Lanka were randomly selected. Three categories of measurements were collected; protocol-based measurements, facility-based measurements and animal-based measurements based on a questionnaire. The microbiological quality of raw milk samples was determined using Total Colony Count (TCC) of bacteria and count of Bacillus cereus. Statistical analyses of data were performed using SPSS 23.0 software. The floor quality was assessed in terms of cleanliness, presence of hoof damageable cracks and the grip. It was found that farmers’ attention on quality of flooring remained low. Improper flooring conditions, including presence of dirt (28%), slippage (62%), and hooves being prone to damage (50%), were observed and correlated (P<0.05), with the prevalence of lameness (12.5%) and hock wounds (12.8%). Based on the survey, concrete flooring was the most prominent bedding type (80%) followed by the soil type (20%). The type of flooring significantly influenced the slipperiness of the shed (P<0.001). A considerable percentage of cows (36.0%) showed signs of wounds, and floor slipperiness significantly (P<0.05) affected the prevalence of wounds. Lower attention on the quality of feeders (14%) and water troughs (12 %) was observed. Positive welfare attitude towards cows was observed in 66% of farmers. The average score of farmer attitudes (6.12) and stockperson attitude obtained, significantly (P<0.001) affected on the floor quality. According to the microbiological analysis, 48 % of the samples were found to be contaminated with Bacillus cereus. The Total Colony Count (TCC) of bacteria and the count of Bacillus cereus varied significantly (P<0.05) across different farms. TCC is significantly correlated (P<0.05) with the floor dirtiness of particular farm. However, there was no significant difference (P>0.05) in between the floor type, TCC and Count of Bacillus cereus. The current study highlighted the critical welfare issues of dairy cows in Naththandiya area and some of these welfare issues had impact on the quality of raw milk. Therefore, it is essential to improve management practices and increase stockperson awareness to enhance dairy cow welfare and there by the quality of raw milk.
Sea moss as an alternative gelling agent to develop a cost-effective in vitro culture medium for the propagation of Phalaenopsis cv. Pink lip
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Wishwakulathil, D. T.; Priyadarshan, A. I. S.; Senanayake, S. P.; Lakmali, G. B. T.
Genus Phalaenopsis is an ornamental orchid with the greatest commercial importance in the world floriculture industry. The propagation of Phalaenopsis is difficult by conventional breeding due to delayed flowering and uneven characteristics of flowers. Therefore, conventional Phalaenopsis cultivation is ineffective for large-scale production. At present, the tissue culture technique is extensively used for the mass propagation of Phalaenopsis. Tissue-cultured plants are more expensive than traditionally propagated plants due to the high cost of the chemicals used for the preparation of tissue culture media. Agar is widely used as a gelling agent and the most expensive ingredient in the preparation of tissue culture media. Developing a cost-effective invitro culture media using low-cost components is one strategy to reduce the production costs of tissue-cultured plants. The use of alternative gelling agents to replace the agar can highly contribute to reducing the cost of in-vitro culture media in tissue culture than other components. The main component of sea moss is carrageenan, a gelatinous substance used to thicken or as a solidifying agent. The ability of carrageenan-based hydrogels to produce thermos-reversible gels and viscous solutions makes them a desirable option for extensive use as a gelling agent. The objective of the present research was to assess the performance of sea moss as an alternative gelling agent to determine the effectiveness for in vitro propagation of Protocrom-like bodies (PLBs) of Phalaenopsis cv. Pink lip. Growth performance of PLBs of Phalaenopsis cv. Pink lip was used to assess the effect of sea moss as an alternative gelling agent. PLBs (0.020g) were transferred to ½ MS medium containing agar as a gelling agent, and ½ MS medium containing sea moss as a gelling agent. Cultures were maintained for four months and the growth performance of PLBs was evaluated, with fresh weight as a parameter at 30 days intervals. There was no significant difference observed in the mean fresh weight of PLBs throughout the fourmonth period, incubation in ½ MS medium containing agar, and medium containing sea moss as an alternative gelling agent. Moreover, there was no significant difference between the contamination percentages of the agar-containing medium and sea moss-containing medium. According to the cost calculation, the cost reduction resulting in the medium with sea moss as an alternative gelling agent was 79.81% compared to the conventional agar as the gelling agent. In conclusion, the application of sea moss as a gelling agent in tissue culture media can be utilized to achieve the optimum benefits for in vitro propagation of PLBs of Phalaenopsis cv. Pink lip. Based on the findings, sea moss can be recommended as a cost-effective alternative gelling agent for the propagation of Phalaenopsis cv. Pink lip using protocorm-like bodies.
A study on a natural rubber and coconut coir-based carbon black composite
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Fernando, H. S. R. R.; Seneviratne, V. A.
Carbon black (CB) is extensively employed as a reinforcing filler in various industrial applications. Widely available polymer-filler composites are synthetic. A main motive of this research was to synthesise and characterise an eco-friendly polymer composite for applications in bicycle tyre and tube industry. The study utilised coconut coir to produce CB and used it as the filler in natural rubber (NR). The coconut coir-based carbon black (CCCB) was prepared by the combustion of coconut coir at 200 0C in a nitrogen atmosphere. Instead of sulphur, pentane-1,5- diylidenediamine (PDD) with equal amounts of ammonia and glutaraldehyde was employed as a cross-linking agent at a low temperature to process NR. The NR and CCCB composites (NRCCCB) were synthesised incorporating 50 mL of NR latex, 6 ml of PDD solution, and different amounts of CCCB. The mixture was stirred at 45 0C for 3 hours, casted into the moulds and made NR-CCCB composites having different weight percentages of CCCB (0, 2, 4, and 6%). The structural properties and mechanical properties, including Young’s modulus, tensile strength, and elongation at break, were assessed to evaluate the influence of CCCB on the composite material. X-ray diffraction was conducted on CCCB, and scanning electron microscopy was conducted on both the composites and CCCB to understand the structural changes and morphological characteristics. The X-ray diffraction analysis indicated that the CCCB is inexhibit an amorphous phase. Morphological analysis revealed a uniform dispersion of CCCB within the rubber composite, which contributed to the enhanced mechanical properties observed in the composites. The particle size of CCCB was estimated to be 70-80 μm. The density of NR-CCCB increased from 887 kg m-3 to 1241 kg m-3 by 40% with the increase in filler loading. Universal testing machine was used to study the mechanical properties of NR-CCCB and the reference bicycle tube. The results demonstrate the increase of tensile strength and Young’s modulus of NR-CCCB 0.75×106 N m-2 to 1.32×106 N m-2 and from 0.72×106 N m-2 to 1.25×106 N m-2 respectively, with increasing filler content, resulting in increased hardness, stiffness, and strength of the rubber. However, the elongation at break of NR-CCCB decreased from 476% to 422% with increasing filler content, indicating a decrease in the flexibility of the NR composites. The density and Young’s modulus of the reference bicycle tube were measured as 1262 kg m-3 and 5.67×106 N m- 2 respectively.
Computational investigation of novel Curcumin derivatives as anti -Tuberculosis Agents
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Amarasena, M. W. K. A.; Dahanayake, J. N.
Tuberculosis (TB) remains a major global health burden, necessitating the development of novel and effective anti-TB drugs. Curcumin a naturally occurring compound found in turmeric has shown potential as an antimicrobial agent, including activity against Mycobacterium tuberculosis the causative agent of TB. In this computational study, the potential of natural derivatives of curcumin as anti-TB drugs was investigated using molecular docking studies and molecular dynamics (MD) simulations. Bedaquiline was used as the reference drug. Using Auto Dock 4.2, molecular docking studies were performed to predict the binding affinities and binding modes of a library of curcumin derivatives with the selected TB targets. The outcomes of the molecular docking studies showed that numerous curcumin derivatives have high affinity for the targeted proteins: Decaprenylphosphoryl-β-D-ribose oxidase protein, Dihydrofolate reductase protein, Enoyl- {acyl-carrier protein} reductase (NADH) protein, InhA 4,3-oxoacyl-(Acyl-carrierprotein) reductase protein, Pantothenatekinaseprotein, UDP-N-Acetylmuramoyl-L-Alanyl-DGlutamate-2,6 Diaminopimelateligase protein. Insights into prospective curcumin derivatives' modes of action as long-term control drugs were offered by the docking scores and interaction profiles. The key interactions influencing the binding process were also understood by investigation of the binding modes. The stability and dynamic behaviour of the chosen curcumin derivatives in complex with the TB targets were examined using MD simulations. These simulations allowed for the long-term study of conformational changes, flexibility, and stability of the derivatives of curcumin within the binding pockets of TB targets. Understanding the dynamic behaviour and interactions of the curcumin derivatives with TB targets was made possible by MD simulations. Root mean square deviation (RMSD) and root mean square fluctuation (RMSF) are two metrics used to assess stability. The results of the docking were supplemented by information from the MD simulations, providing a thorough insight into the binding modes and stability of the curcumin derivatives. By estimating binding affinities through the use of Auto Dock's advanced scoring methods, it was possible to calculate binding free energies and it revealed that all derivatives except one have good binding affinities with the studied proteins. It helped to reveal that the studied natural derivatives clarify the relative potency and selectivity of the derivatives for the tuberculosis targets. In conclusion, the computational findings of this study suggest that natural derivatives of curcumin hold promise as anti-TB drugs. These findings provide a basis for further experimental investigations and optimization of the identified curcumin derivatives as potential candidates for the development of novel anti-TB drugs.
Optimising the power generation cost of microgrids using genetic algorithms - An analysis of the impact of crossover and mutation rates
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) De Silva, S. S. K. A
This study focuses on optimising microgrid costs, with a particular emphasis on the influence of crossover and mutation rates by applying genetic algorithms. As the demand for decentralised energy solutions in isolated and underserved areas grows, microgrids have gained popularity for their ability to incorporate renewable energy sources efficiently. However, their benefits over conventional power generation systems can diminish if not configured properly. The primary objective of this research is to identify the optimal operational conditions for harnessing genetic algorithms to optimise microgrid costs, with a specific focus on the Sri Lankan energy market. This endeavour aims to promote decentralised microgrid technologies and enhance the reliability of the energy service sector. Our methodology employs a Python-based genetic algorithm that iterates through 100 generations to identify the most cost-effective operational settings for microgrids. The cost optimisation equation considers operational expenses for each unit, carbon dioxide emissions costs, and the present value of future running expenses. The future running expense involves a summation over all power generation units, where the present value of the future cost of owning and operating each unit is calculated based on the discount rate and unit lifetime. Elitism is incorporated in the algorithm to preserve the best-performing individuals in each generation and increase the likelihood of converging towards the global optimum. To evaluate the impact of crossover and mutation rates on fitness, a series of experiments were conducted. The null hypothesis stated no significant effect on the fitness of a generation, while the alternative hypothesis considered a significant effect. For the crossover rate experiment, values ranging from 1% to 50% were tested by switching specific bits in the gene representation. The experiment was repeated 100 times to obtain average values and minimise outliers. Similarly, the mutation rate experiment included values from 1% to 50%, with random bit flips according to the specified probabilities. The experiment was also repeated 100 times for accurate evaluation. Statistical analysis relied on the Kruskal-Wallis H-test, with a subsequent Dunn post hoc test to identify significant pairwise differences in mutation rates. The Dunn post hoc test, using Holm’s method for multiple comparisons, revealed significant differences in mutation rates at various levels of significance. Notably, no significant differences were found between mutation rates at the 50%, 25%, and 20% levels of significance. However, at the 10%, 5%, and 1% levels of significance, there were significant differences between certain pairs of mutation rates. It is important to consider that while a higher mutation rate tends to correlate with better fitness values, it can also lead to inconsistent results, potentially affecting the final output of the algorithm. Our study finds that crossover rates have minimal impact on microgrid cost optimisation using genetic algorithms. However, extreme values affect convergence and speed. Mutation rates significantly influence outcomes, with the ideal range being 1% to 10%. This insight aids energy professionals in optimising power generation strategies in Sri Lanka, driving the nation towards a sustainable and resilient energy market.
Investigation of antioxidant and antityrosinase activity of Bauhinia kockiana and Cocos nucifera var. aurantiaca
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Batagoda, H. M.; Weerasiri, K. C.
Tyrosinase is a widely distributed enzyme in the body that plays an important role in melanogenesis. An increase in melanin synthesis can lead to many skin disorders. This research has been conducted on two different plant varieties that can be commonly found in Sri Lanka, Bauhinia kockiana and Cocos nucifera var aurantiaca, more commonly known as King Coconut, to investigate their antioxidant and antityrosinase activities. Bauhinia kockiana was extracted by hot extraction method (Soxhlet extraction) using methanol as the solvent, and the King Coconut water sample was freeze-dried. The antioxidant activity of the samples was analyzed using the DPPH radical scavenging assay, while the enzyme-based tyrosinase inhibition assay was conducted to evaluate the antityrosinase activity, where Agaricus bisporus was used to extract the enzyme. Bauhinia kockiana (flowers and buds) demonstrated a significant amount of antioxidant activity (IC50: 28.73 ± 1.60 μg/mL) against the standard ascorbic acid (IC50: 38.37 ± 1.18 μg/mL). Both the samples revealed relative antityrosinase activity using L-DOPA as the substrate (IC50:128.70 ± 1.22 μg/mL; B. kockiana, 274.45 ± 1.23 μg/mL; Cocos nucifera var aurantiaca water sample) against Kojic acid, which was used as the positive standard (IC50: 49.47 ± 1.12 μg/mL). The Soxhlet extraction of Bauhinia kockiana indicated considerable antityrosinase activity and according to the results obtained, it can be said that both plant types show moderate antityrosinase activity, and Bauhinia kockiana indicates significant antioxidant properties. Further studies on both varieties should be carried out to identify their principal bioactive compounds, which are responsible for the respective bioactivities. To the best of our knowledge, this is the first research to be done on the hot extraction of Bauhinia kockiana and the water sample of Cocos nucifera var aurantiaca on antioxidant and antityrosinase activities.
Zinc oxide nanoparticles synthesized using Camonea bifida leaf extract as a potential antimicrobial and antibiofilm agent
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Jayalath, C. N.; Kaluarachchi, D. U.; Peiris, M. M. K.
Metal nanoparticles have gained much attention in the biomedical field due to excellent biocompatibility and less toxicity. Zinc oxide nanoparticles (ZnO NPs) have exhibited excellent therapeutic value by acting antimicrobial, anti-cancer, anti-diabetic and anti-inflammatory agent. ZnO NPs are also effective in combating biofilm-associated infections. Only a few investigations have been performed on NP synthesis using C. bifida. This study was conducted to evaluate the in vitro antibiofilm and antimicrobial activity of Camonea bifida-derived ZnO NPs. C. bifida leaf extract was prepared by boiling 2g of dried leaves powder in 40 ml of distilled water at 60oC for 30 minutes. ZnO nanoparticles were synthesized using (Zn(CH3CO2)2) as the reducing agent for Zinc ions. The effect of reaction parameters including zinc acetate (Zn(CH3CO2)2) concentration, leaf extract: Zn(CH3CO2)2 ratio and reaction temperature were optimized to achieve higher yield using UV-Visible spectroscopy ((Zn(CH3CO2)2 concentration: 0.1-0.5 M), leaf extract: Zn(CH3CO2)2 ratio 1:9, 1:7, 1:5, 1:3, 1:1 and reaction temperature : 0oC, 30oC, 40oC, 60oC, 80oC). Nanoparticles were characterized by Scanning Electron Microscopy and Fourier Transform Infrared Spectroscopy (FT-IR). The antimicrobial activity of ZnO NPs was studied against Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 25922), Klebsiella pneumoniae (ATCC 1706), Pseudomonas aeruginosa (ATCC 27853), Candida albicans (ATCC 10231), Candida glabrata (ATCC 90030), Candida tropicalis (ATCC 13803). Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) were studied. Gentamicin (600μg/mL) and Fluconazole (500μg/mL) were the positive controls for bacteria and fungi respectively. Negative control was sterile distilled water. Antibiofilm activity of ZnO NPs was assessed using crystal violet assay for P. aeruginosa and C. glabrata. The optimum conditions were 0.3M Zn(CH3CO2)2, 1:3 ratio and 40℃. UV-Visible peak around 390 nm and precipitate formation confirmed the ZnO NP formation. ZnO NPs were spherical and irregularly shaped and were in the range of 60-70 nm. Functional groups attached on to the surface of NPs such as -OH and -C-H were revealed by FT-IR spectrum. According to UV-Visible spectra, ZnO NPs were stable for 2 months. All selected organisms were susceptible to ZnO NPs. Higher zones of inhibition were given by P. aeruginosa (30.7±0.3 mm), S. aureus (25.7±0.3 mm) and among fungi, C. tropicalis (27.7±0.3 mm). Both the MIC and MBC of ZnO NPs against S. aureus and P. aeruginosa were 3.6 mg/mL. ZnO NPs inhibited the biofilm formation of P. aeruginosa and C. glabrata by 68% and 52% respectively at 28.4 mg/mL concentration. S. aureus, P. aeruginosa and C. tropicalis showed higher susceptibility against the NPs. The highest antibiofilm activity of ZnO NPs was reported against P. aeruginosa. Results suggest that ZnO NPs are an effective antimicrobial and antibiofilm agent against tested pathogenic microorganisms.
A preliminary assessment of odonate (Insecta: Odonata) diversity and abundance in Mihintale lake and Kaludiyapokuna in Mihintale, Anuradhapura
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Rajapaksha, K. A. T.; Hettiarachchi, D. K.
The odonates of Sri Lanka comprise with 129 known species, including 67 species belongs to 12 families where 56 species (43%) are known to be endemic to the country. These organisms are currently threatened due to increase in human population and activities, climatic change, intensive agricultural practices and pollution and in need of conservation. Having less diversity, richness, abundance and distribution surveys is one of the key obstacles in conservation. There have been less surveys of odonates in dry zone areas. This study intended to prepare an inventory of odonates that inhabit two lotic ecosystems in dry zone. Four sample sites were selected from each lotic habitat. Visual observations of adult odonates were conducted by walking along belt transect of 100 x 3m that are adjacent to the water bodies in all four sample sites in the selected two lotic ecosystems. Observations were taken from 0900 h to 1100 h in the morning and 1500 h to 1600 h in the evening for six months from Kaludiya pokuna and Mihintale lake visiting three times per month to each site. The observed individuals were photographed. A total of 3,343 of individual odonates were recorded. A total of 22 species identified using standard field guides, belong to three families, Coenagrionidae (25.90%), Gomphidae (3.26%) and Libellulidae (70.83%), two vulnerable species Aciagrion occidentale and Ceriagrion cerinorubellum, two endemic species Cyclogomphus gynostylus and Pseudagrion rubriceps ceylonicum where one was considered as critically endangered and three nearly threatened species Orthetrum glaucum, Hydrobasileus croceus and Rhodothemis rufa were recorded. The diversity of odonates and abundance was higher in Mihintale lake because Shannon – Weiner diversity index (2.267) and Simpson’s diversity index (0.854) and Eveness (0.817) were high for Mihintale lake. The highest number of individuals that observed was Brachythemis contaminata in both study sites as a total but in Kaludiya pokuna number of individuals that was observed from this species was higher than Mihintale lake. This study shows odonate diversity is high in both lotic habitats that were studied and in Mihintale lake it is higher than Kaludiya pokuna. This study needs to be further expanded taking microhabitat parameters, water quality parameters and expanding it over time and area. Further, both lotic and lentic habitats can be considered with and without/less anthropogenic activities.
Assessment of litter and microplastic pollution in the water and sediment of Hirikatuoya stream, within the Walawe River basin, Sri Lanka
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Lahiru, A. A. S.; Amarathunga, A. A. D.; Malavipathirana, S.; De Silva, D. S. M.; Sivyer, D. B.
Rapid urbanization and mismanagement have led to a surge in plastic pollution in crucial aquatic ecosystems globally therefore accumulation of debris in aquatic ecosystems is rapidly increasing and they are becoming ultimate sinks for the contaminants. This results in a long-term and widespread threat causing a great challenge for remediation. Poor disposal practices and littering behavior of communities have resulted in considerable quantities of litter in river banks and streams affecting their aesthetic appeal and living beings. This study was conducted to understand the status of litter and microplastic contamination at selected locations in Hirikatuoya stream, a remote stream outside the urban environment in the Rathnapura district, Sri Lanka. The percentage of plastic in litter and the percentages of microplastic particles (based on colour and morphotypes) in water and sediments were estimated, and the corresponding polymer types were also identified. Three samples of water were collected from each of the nine locations along the stream from September to October 2022. In the sampling process, the samples were filtered through a 150 μm mesh. Sediment samples were collected from the shoreline of the stream at each location using a stainless-steel scoop covering 30 cm2 of surface area and 2-3 cm depth. Lowdensity particles in the samples were separated by density separation and organic matter in the sample was removed by digestion. Whatman GF/C glass microfiber filter papers of a pore size of 1.2 μm were used for sample filtration. Microscopic imaging was done using a staining method. The ATR-FTIR analysis was performed to identify the polymer type of plastic particle in water samples. The most frequently observed colour for microplastic particles in water and sediments were white (26.87%) and colourless (40.20%), respectively. Based on morphotype, fragments were more abundant in both water (49.62%) and in sediments (59.79%) compared to other morphotypes. The highest microplastic abundance in water (69±22, 60±29, 61±26 items 100 m- 3) and highest abundance of microplastics in sediment (15±5.92 items/kg (top), 7±3.28 items/kg (bottom)) were observed in more human and tourist activity locations. According to the ATRFTIR analysis, polypropylene was the most abundant polymer type in plastic litter (25%). In water polypropylene was the most dominant microplastics (38.10%), followed by low-density polyethylene (14.29%) and polyethylene terephthalate (9.52%). Polypropylene was the dominant microplastics in sediments (32.2%), followed by thermoplastic vulcanizates (22.5%), highdensity polyethylene (19.3%). Accordingly, it can be concluded that the Hirikatuoya stream, which is in a remote area, is contaminated with microplastics. There are potential environmental and health risks to the aquatic biota in the stream and the neighboring communities. Further investigations are required to understand the effect on aquatic animals.