iPURSE 2021

Permanent URI for this collectionhttps://ir.lib.pdn.ac.lk/handle/20.500.14444/35

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Simple and rapid method for underivatized analysis of glyphosate residues in tea (Camellia sinensis) using LC- MS/MS detection
(University of Peradeniya, Sri Lanka, 2021-11-11) Samanthy, Y.; Liyanaarachchi, G.V.V.; Abarna, K.; Weerasekara, R.A.D.S.M.R.; Chathurangani, D.A.U.; Weeraman, P.I.D.; Mubarak, M.N.A.
Tea (Camellia sinensis) is among the most popular beverages around the world. The use of pesticides to abate the frequent attacks on tea plants by pests and invasion by weeds, which pose a threat to the growth and nutrition of tea plants, has become a crucial part in the tea industry and has increased over the years. Glyphosate belonging to the broad- spectrum herbicide category is the most widely used herbicide in the local tea industry. Due to the unavailability of an accurate method, the health risk arising from Glyphosate residues left on dried tea leaves being transferred to tea infusions has been overlooked. This study presents the validation data of an accurate and precise method developed for quantitative analysis of Glyphosate residues in tea using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Glyphosate residues in tea were extracted using water and chloroform. The extracted samples were analyzed using liquid chromatograph coupled to tandem mass spectrometer (LC-MS/MS). Chromatographic separation was achieved on an Atlantis T3 column with isocratic elution. Glyphosate was detected with electron spray ionization (ESI) in negative polarity using multiple reaction monitoring (MRM) transitions. Accuracy evaluated based on recoveries obtained for samples fortified at three concentration levels: low mid and high, covering the working range of the method were within 92%–100%. Precision measured in terms of repeatability and reproducibility expressed as percentage relative standard deviation was below 6%. Detection limit and quantification limit of the method were 1.1 mg/kg and 1.8 mg/kg respectively. The method had a wide linear working range of 1.25–100 mg/kg with correlation coefficient greater than 0.999 over six calibration levels. The method developed in the present study is in compliance with international validation guideline requirements, and is accurate and reproducible enabling simple, rapid and underivatized analysis of Glyphosate residues in tea.
Method validation for quantification of selected non-nutritional sweeteners and preservatives and caffeine in carbonated beverages commercially available in Sri Lanka
(University of Peradeniya, Sri Lanka, 2021-11-11) Jayasooriya, J.A.G.K.; Guruge, K.P.G.K.T.; Madhujith, W.M.T.
A study was carried out on validating a method for quantification of selected non- nutritional sweeteners and preservatives and caffeine in carbonated beverages commercially available in Sri Lanka. A liquid chromatography method with photodiode array detection was developed with SHIMADZU Shim Pack HR ODS column with particles of 3.0*150mm and potassium dihydrogen orthophosphate (pH 4.3) and acetonitrile as mobile phases in 88:12 ratio. Validation was performed in terms of linearity, specificity, reproducibility, recovery, Limit of Detection (LOD), and Limit of Quantification (LOQ) values. Detection was done by photodiode array detector and wavelengths used were 200 nm, 214 nm, 230 nm, 235 nm, 258 nm and 275 nm. Aspartame, acesulfame-K, sodium saccharin were selected as non-nutritional sweeteners, and benzoic acid, sorbic acid were selected as preservatives. Aspartame, acesulfame-K, sodium saccharin, benzoic acid, sorbic acid, and caffeine showed linearity within the 1- 100 ppm range. The correlation coefficient (R² ) for all the compounds tested was higher than 0.996. Recovery of all the compounds ranged between 70% and 120%. The LOD values ranged between 0.054 and 0.097 while LOQ values ranged between 0.18 and 0.32. The percentage relative standard deviations were ≤5 for all the compounds. The extraction process was optimized using the surface response methodology and box Behnken design. Process optimization was carried out by Design-Expert Software Version 12.0. The optimum extraction conditions were found to be ultrasonic temperature 25 °C, time 10 minutes and mobile phase concentration 50% (V/V). Good separation and quantification could be obtained within 15 minutes of total run time.
Rice, soybean, and finger millet Milk-incorporated non-dairy drinking yoghurt analogue with desired food quality attributes
(University of Peradeniya, Sri Lanka, 2021-11-11) Perera, O.D.A.N.; Karunathilake, G.R.K.H.
The development of non-dairy food products has been a growing trend as functional food to respond to the problems of cow‘s milk allergy, lactose intolerance, hypercholesterolemia and vegetarianism. During this study, a plant-based drinking yoghurt analogue was developed using rice (Oryza sativa) ―Suwandal‘‘ with a milky taste and exquisite aroma, finger millet (Eleusine coracana) with high fibre, and soybean (Glycine max) with high protein with improved sensory characteristics. Each milk substitute was prepared by a wet grinding process with optimized water: bean/grain ratio (1:1). The sensory evaluation with 30 untrained panelists selected 25% soy milk: 25% rice milk: 25% finger millet milk ratio, 5% (w/v) sucrose, 2% (w/v) glucose, 3% (w/v) sago starch, 10% (v/v) pineapple pulp as the best formulation. Non-dairy yoghurt analogue was fermented with Streptococcus thermophilus and Lactobacillus delbrueckii sub sp. Bulgaricus. The proximate composition results indicate crude protein (12.03%), crude fat (0.11%), moisture (78.49%), crude ash (0.33%), crude fibre (1.30), and nitrogen-free carbohydrate (7.74%). As functional properties, total phenolic content (5.83 mg (GAE)/g) and DPPH scavenging activity (33.24 mg/mL) were analyzed. The physicochemical and microbial properties were evaluated for a storage period of 21 days. The initial day values revealed the pH (4.56), titratable acidity (0.51% of lactic acid), total soluble solid (13%), viscosity (19.52 mPa.s) and water holding capacity (64.68%). Furthermore, the viability of Lactobacillus remained above 106 CFU/mL up to 14 days and after 14 days, yeast and mould count exceeded the safe level (102 CFU/mL). A shelf life study revealed that the product can be stored up to 14 days at 4 oC with desired food quality. In summary, the prepared cereal and legume blended novel non-dairy yoghurt analogue is a potential candidate to be used as a protein-rich, functional, non-dairy yoghurt analogue to consumers looking for dairy alternatives.
A study on perception and usage of herbs among young adults in Gampaha district
(University of Peradeniya, Sri Lanka, 2021-11-11) Diyapaththugama, D.V.S.S.; Abeynayake, N.R.; Chandrasekara, G.A.P.
Several bioactive compounds present in herbs help in the prevention and management of non-communicable diseases (NCDs) and maintenance of wellness. Relatively less attention is given to studying whether people know and use the available herbs against NCDs, which are public health issues in the country. It is important to study the extent of knowledge, attitudes, and behavior (KAB) on the herbs among young adults, who are the key contributors of the country‘s workforce and the deciders of well-being of the future generations. The objective of this online cross-sectional survey, done on young adults of 20-34 years old, was to determine their levels of KAB on herbs and the associations between KAB and socio-demographics. The pre-tested questionnaire randomly forwarded to respondents through email, Facebook and WhatsApp, was used for data collection from a sample of 344 participants. Respondents showed socio-demographic variations of district, gender, ethnicity, education, income, NCDs presence. Data analysis for exploratory and confirmatory factor analysis was performed with SPSS and AMOS statistical software. AMOS tested the associations between KAB and the socio- demographics. Calculations based on a scoring system revealed that KAB levels were 75, 68 and 48%, respectively. Gender, ethnicity and education levels showed significant correlations with KAB. From a list of 39 herbs, ginger, garlic, curry leaves, turmeric and lime were consumed by the majority. The major knowledge sources were family, books or media. Knowledge on herb-nutrient and herb-prescription drug interactions was lacking. The majority used herbs during common cold/fever and for improvement of immunity. Problems faced during herb consumption were undesirable taste, lack of ingredients and time for preparation. Thus, it was concluded that young adults have high knowledge, medium attitudes and behavior towards herbs; and KAB depends on socio- demographics. It is recommended to conduct future research to determine other socio- demographic factors affecting KAB and plan approaches to replenish the identified gaps in KAB.
Development of aloe vera (Aloe barbadensis Mill) cubes-incorporated set yoghurt
(University of Peradeniya, Sri Lanka, 2021-11-11) Manjitha, K.G.L.; Ranasinghe, R.D.A.K.; Rajawatta, K.M.W.
This study was conducted to investigate the possibility of developing set yoghurt incorporated with treated Aloe Vera cubes and to evaluate the physicochemical, microbial and sensory quality parameters of the product. Aloe Vera cubes treated with sugar syrup were incorporated before the incubation process of yoghurt preparation. Yoghurts prepared with three differently treated Aloe Vera cubes (T1 - heated Aloe Vera cubes at 60 0C and soaked in sugar syrup for two days, T2- non-heated Aloe Vera cubes soaked in sugar syrup for two days, T3 - untreated Aloe Vera cubes) were compared with the control sample arranged in Complete Randomized Design. Products were stored at 4 0C for 21 days and different physicochemical and microbial properties such as pH, moisture, titratable acidity, yeast and mould count were tested at 01, 07, 14 and 21 days of storage. A sensory evaluation was done with 35 untrained panelists to get the consumer attributes. Data were analyzed using one-way Analysis of Variance in Microsoft excel. Results revealed that, pH and titratable acidity were significantly different among the products (p<0.05). The highest yeast and mould counts were presented at the treatment with untreated Aloe Vera cubes (T3). Sensory analysis suggested that the treatment with heated Aloe Vera cubes at 60 0C and soaked in sugar syrup for two days (T1) had the best sensory qualities and it complies with the standards of Sri Lanka Standards Institute up to 14 days of storage under 4 0C. The study concludes that, the set yoghurt incorporated with heated Aloe Vera cubes at 60 0C and soaked in sugar syrup for two days had the best qualities and can be stored up to 14 days at 4 0C without any quality deterioration.
Phospholipase application in milk: Does it improve cheese yield of gouda?
(University of Peradeniya, Sri Lanka, 2021-11-11) Prabashwari, T.I.G.; Vidanarachchi, J.K.; Prasanna, P.H.P.; Jayawardene, L.P.I.N.P.
Gouda cheese is one of the most important and value-added dairy products, which has expanded over the world market as a commodity type cheese. Cheese yield has a great economic importance when determining the profitability of a cheese manufacturing plant. This study was conducted to evaluate the effect of fungal phospholipase A1 (PLA1) from Fusarium venenatum on the yield of Gouda by adding PLA1 prior to renneting of Gouda cheese milk. In the current study, the most appropriate PLA1 concentration on the yield improvement of Gouda was determined out of three different PLA1 concentrations. Thus, four Gouda samples were manufactured from cow milk; T1 (1.26 g PLA1/15 L of milk), T2 (1.44 g/15 L), T3 (1.62 g/15 L) and control Gouda. The compositional analysis of whey, sensory evaluation, compositional analysis and microbiological analysis of Gouda samples were carried out. Standard formats of yield expressions were calculated for all the treatments. The use of high concentration of PLA1 (1.62 g/15 L) in Gouda cheese milk had increased (p<0.05) the actual yield, the milk protein plus fat adjusted yield and the moisture adjusted milk protein plus fat adjusted yield by enhancing fat and crude protein composition in cheese. The sensory evaluation revealed that the Gouda manufactured using minimum concentration of PLA1 (1.26 g/15 L) was highly preferred (p<0.05) by the panelists. Microbiological tests revealed that all treatments were safe to consume within forty-five days of ripening period at 10-17 oC and 80-85% RH. The highest PLA1 (1.62 g/15 L) concentration can be selected as the most appropriate treatment on yield improvement of Gouda which can be further improved in industrial cheese trials.
Effect of ethylene and acetylene treatments on phenolics, flavonoids and antioxidant activity of ambul banana (Musa acuminata, AAB)
(University of Peradeniya, Sri Lanka, 2021-11-11) Maduwanthi, S.D.T.; Marapana, R.A.U.J.
Banana is one of the most consumed fruits in the world. It is rich in bioactive compounds. Since banana usually undergoes induced ripening, it is important to study the effects of ripening agents on nutritional value of banana. The present study was a comparison of total phenolics, total flavonoids and antioxidant activity in flesh of Ambul banana (Musa acuminata, AAB) ripened using ethylene and acetylene generated by Ethephon and calcium carbide, respectively. Banana in same maturity stage were subjected to 1000 ppm ethylene and 1000 ppm acetylene and kept at 20 °C and 80-85% RH until they are fully ripened. A control sample was kept at similar conditions without any treatments allowing natural ripening. The samples were analyzed for total phenolic content (TPC), total flavonoid content (TFC) and antioxidant activity (DPPH, ABTS and FRAP assays) at fully yellow stage (Stage 6). TPC and TFC in control sample were 39.69±0.77 mg of GAE/100 g fresh weight and 2.19±0.14 mg of QE/100g fresh weight, respectively and were significantly higher (p < 0.05) than those in treated samples. There was no significant difference (p < 0.05) in TPC and TFC between ethephon and acetylene treated banana. ABTS, DPPH and FRAP values showed the similar behavior having significantly high scavenging activities in naturally ripened banana compared to treated samples. Ethephon treatment showed the lowest (p <0.05) antioxidant activity where DPPH activity was 409.85 ± 0.96 mg TE*/100 g and ABTS activity was 906.95 ± 1.74 mg TE*/100 g. FRAP activity values were not significantly different (p < 0.05) in acetylene and ethephon treatments. The result showed that ethephon and acetylene treatments at 1000 ppm level can considerably affect bio active compounds in banana.
Effect of marination technique and holding time on physicochemical and sensory attributes of marinated pork chops
(University of Peradeniya, Sri Lanka, 2021-11-11) Mutucumarana, R.K.; Thambawita, S.C.; Mahindarathna, J.
This study was conducted to evaluate the effect of holding time on physicochemical and sensory attributes of marinated pork chops. The experimental design was 3 x 3 factorial arrangement of treatments evaluating three marination techniques (unmarinated control, injection and immersion) and three holding times (4, 8 and 12-h). A total of 63 pork chop samples (40 ± 5 g) obtained from a female fattener pig (12-months old; live weight, 88 kg) were marinated and allocated randomly into treatment combinations. Uncooked and cooked pork chops were analysed for physicochemical and sensory attributes, respectively. An interaction between (P<0.05) the marination technique and the holding time was observed only for pH, cooking yield, marinade loss, hardness, redness and yellowness. Injection marination improved (P<0.05) the marinade uptake than immersion. Holding 8-h after injection marination improved pH of meat (P<0.05). Cooking loss was affected (P<0.01) by the technique of marination. Holding pork chops for 8-h after injection and immersion marination (P>0.05) resulted the highest cooking yield. Meat held for 12-h after immersion marination (4.64%) and unmarinated control (4.45%) held for 12-h resulted the highest (P<0.05) marinade loss. Treatments when held at 8-h reported the highest tenderness. Meat subjected to immersion and injection marination and held for 4 and 8-h increased (P<0.05) the redness (a*). Unmarinated control poorly developed the yellowness (P>0.05) over three holding times. Injection marination resulted the highest scores for flavour, marinade penetration and overall acceptability when held for 8-h. Holding pork chops for 8-h after injection marination maximized cooking yield, tenderness, redness, yellowness while minimizing marinade loss. The panelists preferred mostly the meat marinated using injection method held for 8-h. Direct application of marinade into meat during injection process have resulted meat quality to improve. In conclusion, the injection method with 8-h holding time best contributes to the development of physicochemical and sensory attributes of pork chops.
Geochemistry of rare earth elements in mollusk shells from a sediment core from southeastern Sri Lanka and its paleoceanographic implications
(University of Peradeniya, Sri Lanka, 2021-11-11) Premaratne, K.; Chandrajith, R.; Ratnayake, N.; Li, Si-Liang
Bio-mineralization of carbonate shells is sensitive to changes in the physico-chemical conditions of the ambient water. Despite the possible vital effects, Rare Earth Elements (REE) could be incorporated in biogenic carbonates without major mass fractionation, thus it can be used as a proxy for climate, environmental and oceanographic applications. Mollusk shells (43) from families Veneridae and Potamididae collected at different depths of a sediment core retrieved from the Pottuvil Lagoon were used to trace REE imprints of environment changes around southeastern Sri Lanka during the Holocene. Shells were digested using the reverse aqua-regia (3:1 HNO₃: HCl) method and the REE contents were measured using ICP-MS. Chronology of the sediment core was established by the Bacon age-depth modeling based on calibrated AMS ¹⁴C dates of mollusk shells and bulk sediments. North American Shale Composite (NASC) normalized REE patterns showed that the shells are enriched in light REE (LREE) with prominent negative Eu and Ce anomalies and a slightly positive Gd anomaly. In addition, total REE (∑REE), Y/Ho ratio, and magnitude of LREE enrichment exhibited distinct variations with depth. The phases of increased ∑REE concentration, Y/Ho and enhanced LREE enrichment with troughs or no Ce anomaly were corresponded with increased terrestrial input recorded in lithogenic proxies from 5141 to 4223 BP and from 2918 to 2688 BP. The phases of decreased ∑REE concentration, Y/Ho and declined LREE enrichment with enhanced Ce anomaly were consistent with decreased terrestrial input during 4223-4021 BP and 3537 to 3260 BP periods. Thus, these periods reflect (i) declined salinity (freshening) in the ambient water and a wet climate; (ii) increased salinity in the ambient water and a dry climate; respectively. Based on the whole shell geochemistry of REE, this study was able to reconstruct the paleoceanographic conditions around southeastern Sri Lanka from the Mid to Late Holocene.
Diversity, abundance and distribution patterns of odonata in Royal Botanical Gardens, Peradeniya
(University of Peradeniya, Sri Lanka, 2021-11-11) Atapattu, A.M.P.E.K.; Yatigammana, S.K.
Dragonflies and damselflies are odonate insects (Order: Odonata) associated with water bodies. They are considered as indicator organisms of water quality in aquatic ecosystems. The objective of this study was to identify the Odonata species present in the Royal Botanical Gardens (RBG), Peradeniya to understand the distribution patterns of dominant species and hence to provide guidance for educational activities. Sampling was carried out daily, from December, 2015 to January, 2016 from 0900 - 1600 hours, to record their diversity and abundance in each study site separately. Observations were taken at some selected man-made water bodies, open areas and in the marginal vegetation of River Mahaweli nearby the River Drive. Standard field guides were used for the species identification. A total of 17 Odonata species were recorded including ten damselfly species and seven dragonfly species. Out of the 56 endemic Odonata species in Sri Lanka, only four endemic damselfly species were recorded in RBG, while no endemic dragonfly species were recorded. Therefore, the percentage endemism of recorded damselfly species was 40%. The most abundant damselfly species recorded throughout the study was Ceriagrion coromandelianum (51.89%), while Pantala flavescens (45.64%) was the most abundant dragonfly species. The highest diversity of both damselflies and dragonflies was recorded at Lanka Pond bearing a Shannon Diversity Index value of 1.57 and 1.34, respectively. Shannon evenness values of damselflies and dragonflies at Lanka Pond were 0.682 and 0.688, respectively. Species richness and evenness at Lanka pond was higher than other sites. Most of the sites are dominated by one or two species, reducing species richness and evenness. Though a high diversity of Odonata are recorded from mid elevations to the highlands of Sri Lanka, low diversity was recorded in RBG during this study.
Mechanical exfoliation of large area graphene from Sri Lankan graphite for device application
(University of Peradeniya, Sri Lanka, 2021-11-11) Karunya, M.J.; Suvanya, A.; Sutharsini, U.; Thanihaichelvan, M.
Graphene is known as a unique material with wide range of applications in renewable energy generation and storage, biosensors, and device applications. Single atomic thickness with extremely high electron mobility and a zero-band gap provide many advantages to the graphene as an electronic material. Sri Lankan graphite is known for its very high carbon content and high purity. However, Sri Lanka is still exporting the graphite as a raw material. Recently, the government of Sri Lanka launched a project for value addition of local minerals and the Sri Lankan vein graphite has been identified as a potential candidate in energy storage devices. In this work, we attempted to exfoliate single layer graphene from Sri Lankan graphite and to fabricate field effect transistors and to study their electronic properties. We used a simple scotch tape technique and transferred graphene onto a 100 nm SiO2 coated Si substrate. The thickness and the uniformity of the graphene layer were tested using Atomic Force Microscopy (AFM). The thickness was confirmed to be 0.4 nm and the surface roughness was found to be 0.04 nm. The AFM images also confirmed the growth of double layer graphene also with the thickness of 0.9 nm. The Field Effect Transistor was fabricated by making electrical contact using thermal evaporation of gold and we found that the graphene layer showed an ambipolar current response with a positive Dirac voltage. Our studies suggested that the Sri Lankan graphite is one of best raw material for graphene exfoliation and the graphene exfoliated can be used for device applications.
Measuring individual carbon footprint and exploring its determinants: A case study of Galewela Divisional Secretariat in Matale District, Sri Lanka
(University of Peradeniya, Sri Lanka, 2021-11-11) Disanayaka, D.M.M.G.J.M.
Carbon footprint (CFp) is the measure of the amount of carbon dioxide emission associated with all the activities of a person or other entity. The overall aim of this study was to measure the individual CFp and its determinants of selected samples in the Galewela Divisional Secretariat in the Matale District. The specific objectives were to measure individual CFp, to measure per capita CFp, to identify the factors affecting the individual CFp and to formulate guidelines to reduce CFp. In order to achieve these objectives, primary data were collected from questionnaire surveys and interviews. Secondary data were collected from the journal articles, reports and websites. Convenience sampling method was used and it consisted of 120 respondents in the Pattiwela, Pathkolagolla and Hombawa villages in the Galewela Divisional Secretariat Area. https://www.carbonfootprint.com website was used to calculate the individual CFp. Data were analyzed by using SPSS and MS Excel software. Multiple regression, correlation analysis and descriptive analysis were employed for data analysis. According to the result, the total individual CFp of the study sample is 13.43 tons /month. Of this, the male respondents produce 8.62 tons of CFp and Female respondents released 4.81 tons of CFp. The per capita CFp of the study area is 0.11 tons/ month. Household activities of the respondents produced 27% of CFp per month. Respondents public transportation produced 19% CFp and private transportation produced 15% of CFp. Furthermore, secondary consumption produced 39% of CFp in the study area. The statistical findings revealed that, gender (sig = 0.010), age (sig = 0.01) and monthly family income (sig = 0.000) of the respondents are significantly influenced for the individual CFp in this area. Therefore, this study recommends that people should adopt a sustainable and environmentally friendly lifestyle to reduce their CFp.
Variation of air temperature of Anuradhapura in dry zone of Sri Lanka
(University of Peradeniya, Sri Lanka, 2021-11-11) Wijerathna, L.P.S.D.N.; Meegahakotuwa, U.S.
The climate of Sri Lanka is characterized as a tropical monsoonal. Temperature is one of the most important elements in the tropical climate. Anuradhapura is situated in the dry zone of Sri Lanka and is one of the historical tourist attracted places on the Island. Paddy cultivation is the key farming practice and the irrigation system is one of the main characters in the cultural landscape in Anuradhapura. The main objective of this study was to examine the long-term temperature variation in Anuradhapura. The annual average temperature data has been collected from Anuradhapura station for the period from 1920 to 2019. The data was obtained from the Department of Meteorology, Colombo. To identify long-term variation in temperature, the data set was divided into two observation periods from 1920 to 1969 and 1970 to 2019. The trend was estimated from 1920 to 2019 using the time series and linear regression techniques. The Man- Kendall statistical test was applied to identify significant and non-significant monotonic trends. The result revealed that the annual average temperature in Anuradhapura has been increased by an amount of 0.9 °C during the 1970-2019 period compared to the 1920-1969 period. The annual average temperature has shown a statistically significant (P<0.05) increasing trend during 1920-2019. The rate of increase of annual average temperature is in the order of 0.017 °C per year. The study revealed that the temperature has a significant increasing trend during the last 100 years in Anuradhapura. The temperature increases will negatively impact the irrigation water management system, paddy productions, other human activities and natural environmental processes of Anuradhapura.
Microbial toluene utilization capability in petroleum waste contaminated soil
(University of Peradeniya, Sri Lanka, 2021-11-11) Gunasinghe, Y.H.K.I.S.; Deeyamulla, M.P.; Rathnayake, I.V.N.; Kannangara, A.T.
BTEX (Benzene, toluene, ethylbenzene, and xylene) compounds are volatile monoaromatic hydrocarbons common in crude petroleum and petroleum products. Petroleum hydrocarbon contaminated soil microflora was qualitatively and quantitatively examined for its toluene removal and degradation capability. Petroleum hydrocarbon contaminated soil was collected from a fuel filling station in Kiribathgoda, Sri Lanka. The soil suspension was prepared. Flask with Bushnell Haas broth (9.00 mL) with toluene 20% (v/v) was incubated for one day to get equilibrated with toluene, and soil suspension (1.00 mL) was transferred to the flask. Flasks were sealed with rubber silicone septa and paraffin tapes and incubated at 100 rpm, 30 °C. Soil suspension was enriched in 3 stages as 1st, 2nd and 3rd by providing toluene as the whole carbon source. Headspace air (1.00 mL) of each enrichment sample was withdrawn after one, four, and seven days and manually dissolved in dichloromethane (2.00 mL) and analyzed using Gas Chromatography-Mass Spectrometry (GC-MS). After seven days, the number of toluene degrading bacteria in each enrichment was isolated using BHA, and plates were incubated at 30 °C for seven days with a toluene containing filter pad. The toluene reduction percentages were calculated compared to the initial toluene level in the headspace of the 1st, 2nd, and 3rd enrichments; it revealed 54.88%, 54.42%, and 79.36% toluene reduction within three days. After six days, 1.76×103 , 6.68×105 , 1.57×106 CFU/mL of bacteria from 1st, 2nd, and 3rd enrichments reduced the initial toluene amount by 67.87%, 45.70%, and 80.94%, respectively. During the enrichment, the number of bacteria present in the suspensions and the toluene utilization amount by bacteria increased. Five morphologically distinct bacterial colonies were isolated. According to the results, headspace toluene reduction pattern is obtained, which may be helpful for the development of novel environmentally friendly VOC bioremediation methodologies.
Spatial variation of the quality of surface water over different land use types in upper Mahaweli catchment
(University of Peradeniya, Sri Lanka, 2021-11-11) Somasiri, I.S.; Hewawasam, T.; Rambukkange, M.P.
The Mahaweli, Sri Lanka‘s longest river, is used extensively for supplying domestic water. However, its water is polluted in many places at different scales. We monitored the quality of water and suspended load of three micro-catchments of the Ma Oya (ca. 1 km2 ), six-sub catchments (ca. 50-100 km2 ) of Upper Mahaweli Catchment, and the Mahaweli River at Gatambe on monthly basis over a hydrological year (October 2018 to September 2019). Land use maps of these catchments were developed in the ArcGIS platform to examine the effect of land use on the quality of water. The mean and standard deviation of measured parameters were as follows: temperature (27.2± 3.8 oC), pH (7.3± 0.6), Electrical Conductivity (102.2± 74.9 μS/cm), alkalinity (49.7± 48.3 mg/L), hardness (53.1± 42.6 mg/L), Nitrate (1.6± 1.5 mg/L), Phosphate (0.1±0.16 mg/L), Sulphate (3.3± 4.7 mg/L), Fluoride (0.1± 0.06 mg/L), Chloride (6.7± 4.2 mg/L), Calcium (7.7± 8.0 mg/L), Sodium (3.1± 3.1 mg/L), Magnesium (1.5± 1.6 mg/L), Iron (168.8± 172.3 μg/L), Aluminum (42.3±60.0 μg/L) and Phosphorus (1.7± 2.0 mg/L). The catchments were categorized based on the land use as a percentage: (i) forest (ii) tea (iii) crops (seasonal crops, paddy, agricultural farms, pepper, chena, and coconut cultivation), and (iv) home gardens. Nitrate, Phosphate, and Sulphate concentrations of surface water showed a positive correlation (0.50, 0.61, and 0.79, respectively) with land use cover of crops. Nitrate concentration also showed a positive correlation (0.51) with land use cover of home gardens. The suspended load concentration positively correlated with Nitrate (0.48) and Sulphate (0.84). Alkalinity, Hardness, pH, EC, Total Dissolved Solids and, K, Mg, Na, Ca, Al, Fe, Fand Clconcentrations also demonstrated positive relationships with crops. Therefore, this study reveals that land use cover of crops and sediment delivery from the catchments play a major role in polluting the Mahaweli river.
Performance analysis of monolayer nanoporous graphene oxide membranes for pressure-driven desalination: A molecular dynamics study
(University of Peradeniya, Sri Lanka, 2021-11-11) Heenkenda, K.Y.; Wijekoon, H.; Zhiguo, W.; Ranatunga, R.J.K.U.; Chen, X.; Jayasundera, A.C.A.; Weerasooriya, R.
Although Sri Lanka is not a water scarce nation, over 3.5 million people currently suffer from acute drinking water stress due to high salinity. Both reverse osmosis (RO) and nanofiltration membranes (NM) pressure-driven methods are widely used in water desalination. However, the resulted water is often overtreated causing problems due to lack of solutes in the permeate. Therefore, the development of tunable membranes for permeation of ions as required in the permeate is timely. Graphene and its derivatives have shown promise in the fabrication of pressure-driven membranes for water desalination. However, the fabrication of tunable graphene derived membranes is challenging. To complement experimental work, we have designed a new model graphene oxide membrane in silico and examined its selective the molecular sieving properties using molecular dynamics simulations. Mono-layer graphene and graphene oxide membranes were simulated using the LAMMPS code with the OPLS-AA force field to determine interactions between the membrane, water molecules and salt ions. The TIP3P was applied to water molecules with the SHAKE derived constrains. The initial simulation system contained membrane and water molecules sandwiched between two pistons, which allows for external pressure on the solution on either side of the membrane. We developed a molecular dynamics model to investigate monolayer nanoporous graphene and graphene oxide membrane performance at a pressure of 2000 atm and calculated the salt rejection and solute flux gradients. When comparing to graphene with graphene oxide membranes, graphene has a better salt rejection ability. Due to the functional groups present on graphene oxide membrane, solute flux is higher (around 70-80%) when compared with graphene membranes. Calculations of the thermodynamic parameters of water permeation and diffusion coefficient values of the membrane system under the realistic pressure range, 150 atm to 2500 atm are currently in progress. The data will be used in refining our MD model that is vital in designing experiments for membrane fabrication with desired performance.
Pollen morphology, viability, and in vitro germination studies in Carica Papaya L.
(University of Peradeniya, Sri Lanka, 2021-11-11) Rathnathunga, E.U.U.; Hewage, W.H.N.Y.; Chandana, E.P.S.
Carica papaya L. belongs to the family Caricaceae which is a gynodioecious plant. The systematic morphological and floral diversity of Sri Lankan varieties are yet to be characterized. The objective of the study was to investigate the floral morphology, pollen viability and germination ability of the red lady variety and a local variety. The research was conducted at the Faculty of Technology, University of Ruhuna, Karagoda- Uyangoda, Kamburupitiya, Sri Lanka of IL1A agroecological region. The experiment was designed in Randomized Complete Block Design (RCBD) of 30 replicates in each variety with 1.8 X 1.8 m spacing. The floral morphology of two selected varieties was observed through visual observations and the light microscope. The dimensions of the flower morphology were measured using a vernier caliper. The pollen viability rate and the germination rate were tested with the iodine-potassium iodide test and the in vitro pollen germination test. Both the pollen viability rate and the pollen germination rate were observed through the imagery microscope and the hemocytometer using 3 replicates of each sample. The data were analyzed by t test through the Analysis ToolPak of MS Excel. Papaya has three flower types: female, male, and hermaphrodite. The male flower of the red lady had five petals and ten stamens while the local variety possessed four petals and eight stamens. The stamens‘ arrangement of the hermaphrodite flower of the two varieties was comparatively different. The height of the male (40.1 mm) and the hermaphrodite flowers (64.7 mm) of the red lady variety were significantly greater than local variety (30.7 mm and 48.8 mm, respectively). The in vitro germination rate of pollen from male flowers was significantly higher (22%) in local variety while the in vitro germination rate of the pollen from hermaphrodite flowers were significantly higher (50%) in red lady variety compared to local variety. The viability rate of the pollen from male flowers were higher in red lady variety (98%). The study highlights the importance of strengthen the production of local varieties and understand its yield potential.
Molecular characterization for identification of endangered Sri Lankan leopard: A forensic application
(University of Peradeniya, Sri Lanka, 2021-11-11) Gunawardana, G.A.; Jayasekara, P.P.; Wijethunga, W.M.R.R.; Palliyeguru, M.W.C.D.; Kasagala, K.H.D.T.
Sri Lankan Leopard (Panthera pardus kotiya) is an endemic subspecies and listed under endangered species by the International Union for the Conservation of Nature (IUCN). Even though killing of leopard is illegal, few incidences have been reported recently in Sri Lanka. To implement protection law effectively, precise forensic declaration of suspected body parts is necessary. Current investigation was conducted to identify the species from meat and fur samples suspected to be of a Sri Lankan Leopard using molecular sequence data. DNA from meat (n=2) and fur (n=2) were extracted using a commercial genomic DNA extraction kit (Qiagen, Germany). PCR was performed using previously published mitochondrial 16S rRNA primers and amplicons were sequenced bi-directionally by Sanger-sequencing method. Consensus sequences were generated in BioEdit 7 and MEGA 10, where identical sequences resulted from all samples. A phylogenetic tree was constructed in MEGA 10 under maximum parsimony criterion at 500 bootstrap replicates. National Center for Biotechnology Information (NCBI) BLAST search for consensus sequence showed 99.58% identity and 100% query cover with Panthera pardus mitochondrion complete genome with an E-value of 0.0 showing near complete match. Obtained phylogeny based on mitochondrial 16S rRNA sequence further suggested that P. p. kotiya is closely related to leopard subspecies from Russia (P. p. orientalis) and China (P. p. japonensis). However, mitochondrial 16S rRNA sequence of Indian subspecies P. p. fusca was not available in GenBank for comparison. This is the first reported genotypic identification of Sri Lankan subspecies kotiya by 16S rRNA primers and sequence alignment. Sequences generate in this study for P. p. kotiya were submitted to GenBank under the accession number MW703705. Present study provided new data on 16S rRNA sequence of subspecies P. p. kotiya in Sri Lanka.
Evaluation of the effect of land-use practices on nitrate contamination of groundwater in Kalpitiya
(University of Peradeniya, Sri Lanka, 2021-11-11) Dilshara, R.M.P; Amarasinghe, L.D.; Handapangoda, H.M.A.K.; Edirisinghe, J.C; Gimhani, D.R.; Herath, H.M.I.K; Swarnathilake, D.S.G.G.C; Udayanga, N.W.B.A.L.
Regardless of the high agricultural productivity, the intensive agricultural practices in Kalpitiya have resulted in groundwater contamination with nitrate. This study was conducted to assess the influence of different land-use practices on the nitrate contamination of groundwater in Kalpitiya, with special emphasis on agricultural uses. Groundwater samples were collected at monthly intervals from November 2018 to January 2021 from 50 potable and agricultural wells located in five sentinel sites, namely Nawakkadu, Narakkalli, Thalavila, Kandakuli, and Kalpitiya town. In addition, the existing land-use practices surrounding the respective wells (within 150 m radius) were recorded. Electric Conductivity (EC), Total Dissolved Solids (TDS), salinity, nitrate, and phosphate concentrations of the water samples were measured using standard methods. The General Linear Model (GLM) followed by Tukey's pairwise comparison and Distance-based Redundancy Analysis (dbRDA) were used for statistical analysis. The highest pH and phosphate levels and the lowest conductivity, nitrate, salinity and TDS levels in groundwater were detected during the second inter monsoon period, followed by the North-East monsoon. The effect of the land-use practices on the variations of studied water quality parameters was found to be significant (p<0.05), except for phosphate. Agro-wells located surrounding the onion cultivations, showed the significantly highest nitrate (78.6±16.4 mg/L), EC (2.2±0.3 mS/cm), salinity (1.1±0.2 %), and TDS (1111.0±157.0 mg/L) levels, followed by tobacco and radish cultivations. On the contrary, pomegranate, eggplant, papaw cultivations and residential areas showed lower levels of the above parameters. In the dbRDA analysis, onion and tobacco cultivations formed a cluster, while residential areas, pomegranate, papaw, and coconut cultivations formed a separate sub-cluster verifying the findings of GLM. Therefore, crop diversification or shifting towards less nitrate leaching crops such as pomegranate, eggplant and papaw cultivations is recommended to regulate the nitrate contamination of groundwater in Kalpitiya.
Preliminary study of age and growth of select elasmobranch fishes in Sri Lanka based on vertebral growth rings
(University of Peradeniya, Sri Lanka, 2021-11-11) Bandara, A.G.G.C.; Tanna, A.; Fairoz, M.F.M.; Fernando, D.
Though Sri Lanka has a high diversity of elasmobranchs, species-specific studies are relatively few. Present study investigated the preliminary suitability of species for comprehensive age-growth studies as a first step for larger scale data collection. A systematic analysis of vertebrae obtained from fisheries bycatch was conducted to determine the optimum vertebrae and processing for best ring visibility as determined by three independent readers. Acroteriobatus variegatus (AV), Carcharhinus leucas (CL), Centrophorus sp. (GC), Himantura leoparda (HL), Himantura uarnak (HM), Isurus paucus (IP), Maculabatis arabica (MA), Maculabatis gerrardi (MG), Mobula mobular (MM), Mobula tarapacana (MT), Neotrygon indica (NI), Pastinachus ater (PA), Pateobatis jenkinsii (PJ), Prionace glauca (PG) and Rhinoptera javanica (RJ) were studied. According to the one-way ANOVA test, the central region had the best visibility for AV. There was no significant difference in ring visibility for PJ, HL and NI among the three regions. Also there was no significant difference in both bleaching and drying methods for all species. The vertebrae ring count method was not successful for GC. Vertebral ring counts for other sectioned species revealed that females live longer than males. The Von Bertalanffy growth curve was partially developed for AV and PJ, which accounted for more than 30 specimens each. However, a lack of young individuals prevented a complete life-history curve. Maximum age for male AV and PJ were estimated at 10 and 14 years, respectively, while for females it was 13 and 15 years, respectively. Analyses of preliminary data suggest that the central section of AV, with no bleaching or drying, is the most optimum method for ageing these species. Based on this study and other existing methodological procedures, it is recommended that the feasibility of counting rings be conducted for each species before proceeding to larger sample collections to support conclusions.

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