RESCON 2023

Permanent URI for this collectionhttps://ir.lib.pdn.ac.lk/handle/20.500.14444/5953

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Investigation of release and deterioration of chrysotile fibres in corrugated asbestos-cement roofing sheets
(Postgraduate Institute of Science, University of Peradeniya, Sri Lanka, 2023-11-03) Sanjeewa, R.A.L.; Pitawala, H.M.T.G.A.
Asbestos sheets have gained popularity as roofing materials in Sri Lanka due to their affordability and durability. The objective of the research is to assess the deterioration of asbestos sheets under tropical conditions and their environmental impact. Samples were collected from Giriulla, Sri Lanka, which experiences a dry climate with slightly acidic rainfall. The collected samples of rainwater directly and rainwater that passed through the asbestos cement sheets during different rainfall events were analysed to measure total hardness and Mg²⁺ concentration using the EDTA titrimetric method and atomic absorption spectrometry, respectively. The findings indicated that the Mg²⁺ concentration in the surface runoff water collected from the roof was higher than that of the direct rainwater in two rainfall events. In another rainfall event, the Mg2+ concentration was almost equal in both types of samples. This suggests that the asbestos cement sheets contribute to an increased presence of Mg²⁺ in the runoff water from the roof. The rainwater collected from the surface runoff of the asbestos sheet roofing contained an average of (6.62 ± 0.14) ×10⁴ fibres per square meter per litre. These fibres were observed to have lengths ranging from 40µm to a few millimetres. It is inferred that the dispersal of these fibres into the surrounding areas is facilitated by rain and wind. The optical microscopic imagery of the surface of asbestos sheets also revealed that fibres can be easily removed from the surface of asbestos sheets. The current study suggests that fibrous materials can easily detach from the cement matrix of degraded asbestos sheets upon contact with rainwater and subsequently be released into the environment. These fibres are particularly susceptible to inhalation, which can lead to severe health issues. Applying a sealer as a preventive measure can be recommended to mitigate the deterioration of asbestos sheets.
Microplastic pollution in Dondra Lagoon, southern coast of Sri Lanka: Influence on habitat and feeding modes of selected fish species
(Postgraduate Institute of Science ,University of Peradeniya, Sri Lanka, 2023-11-03) Bandara, H.M.N.N.; De Silva, H.S.D.R.; Wijayathilaka, H.D.; Kodikara, K.A.S.; De Silva, P.M.C.S.
Microplastic pollution is a leading environmental concern across the globe. Microplastics resemble plastic particles that are less than 5 mm in diameter, and primary and secondary forms pose potential impacts on biodiversity within a wide spectrum. Several studies in Sri Lanka have identified microplastic pollution in coastal ecosystems. Dondra Lagoon is a highly impacted site on the Southern coast of Sri Lanka. This study aimed to investigate the impact of microplastic pollution on this particular ecosystem. Surface water samples and bottom sediment samples were collected from thirty sampling sites within the lagoon, along with 37 fish samples for analysis. Microplastic contamination was evident in surface water and sediment samples. Moreover, microplastics were identified in selected fish, as this exposure could be closely associated with their habitats and feeding modes. Notable variation of lagoon hydrology was identified during the rainy season. Although the lagoon opening remained blocked by sand bars during the study period (July 2022), a high variation of microplastic contamination within the study area was not observed. The mean ± SEM microplastic contents ranged between 7.11 ± 1.53 and 9.83 ± 2.56 items per litre in water and between 56.25 ± 12.6 and 116.67 ± 44.9 items per kilogram in dry sediments. The highest mean ± SEM microplastic accumulation (531 ± 155 items per kilogram of body weight) was identified in Caranx sexfasciatus species, while the species Heteropneustes fossilis showed the lowest accumulation (11.07 ± 5.66 items per kilogram of body weight). The majority of the identified microplastic particles were fibres and fragments. Microplastic particles were identified in blue, green, red, white and black colours, along with some transparent fibres. A notably high impact of microplastic pollution within this ecosystem was identified, and the sources of the microplastics could be linked with fishing practices, households, and improper waste disposal around the lagoon. Hence, implementing better management strategies is of utmost importance for mitigating microplastic pollution in this ecosystem.
Characterisation of hydrogen peroxide-induced programmed cell death in selected microcystin producing cyanobacteria: Cytotoxic effects on cellular microcystin content
(Postgraduate Institute of Science, University of Peradeniya, Sri Lanka, 2023-11-03) Gunathilaka, H.M.S.A.T.; Wijesinghe,W.R.P.; Magana-Arachchi, D.N.
Cyanobacterial blooms can undergo programmed cell death (PCD) under natural and artificial stress conditions. This study aims to reveal the effects of PCD induced by H₂O₂ on cyanotoxin production, cell viability, and morphology of different cyanobacteria: Microcystis sp., Fischerella sp., Nostoc sp., Pseudoanabaena sp., and Leptolyngbya sp. Cyanobacteria (Initial cell concentration~1x108 Cells mL ⁻¹) were grown as batch cultures in BG11 media. The cultures were grown in four different H₂O₂ concentrations:10 mg L⁻¹,60 mg L⁻¹,125 mg L⁻¹,250 mg L⁻¹, and four different exposure durations:3 hrs, 6 hrs, 9 hrs and 12 hrs. Methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay was performed to analyse the cell viability by recording the absorbance at 595 nm using a microplate reader (FLUOstar Omega) and compared using OD₇₅₀ values of controls. Microcystin (MC) was analysed using High-Performance Liquid Chromatography with reference to the MC standard (SIGMA ALDRICH 33578). Treatments were observed after 24 hrs using Olympus CKX41 inverted fluorescence microscope. The cultures significantly influenced cytotoxicity at different H₂O₂ concentration levels (p<0.05). The maximum cytotoxicity was observed within Pseudoanabaena sp. and Leptolygbya sp., reducing cell viability by 75.34% and 96.19%, respectively. Microcystis sp. and Fischerella sp. had the highest intracellular MCs content: 0.982 mg L⁻¹ and 0.8519 mg L⁻¹, respectively. A positive correlation was found between average cell viability (%) and MC-LR content in cells (r=0.518, p>0.05), while a weak correlation was found between average cell viability (%) and total MC content in cells (r=0.329, p>0.05). A dose of 250 mg L⁻¹ H₂O₂ at 24 hrs caused a decrease in green colour and chlorophyll red fluorescence intensity in cells compared to the controls. The Apoptosis conditions at higher H₂O₂ concentrations and extended incubation periods significantly affect cyanobacteria’s cytotoxicity, morphology, and MC production and increase cyanotoxin production in cyanobacterial cells. Further investigation through molecular analysis is necessary to study cyanotoxin production in the context of apoptosis.
The role of selected abiotic and biotic factors in changing the abundance of critically endangered, point endemic Pethia Bandula
(Postgraduate Institute of Science, University of Peradeniya, Sri Lanka, 2023-11-03) Lenagala, J.C.; Amarakoon, V.; Gunasekara, V.; Dayawansa, P.N.
Bandula barb (Pethia bandula) is a critically endangered and point-endemic freshwater fish species inhabiting a stream at Galapitamada (7.15801035°N, 80.23963686°E), Sri Lanka. However, our understanding of the habitat characteristics of this species is underdeveloped. The habitat characteristics can be defined by measuring the abiotic and biotic factors, which have the potential to influence the abundance of the species. Twenty-three points, 50 m from each other, were sampled. The abundance of the fish was determined by conducting bank counts within a one-square-meter area for ten minutes. Water temperature, pH, conductivity, light intensity, fractional green canopy cover, water flow, depth and turbidity were measured. In addition, the availability of aquatic plant Cryptocoryan sp. was determined. Statistical analysis was performed using R statistical software. The multiple linear regression analysis revealed that the pH, light intensity, and water temperature were significantly correlated with the abundance of P. bandula. While pH showed a positive correlation with P. bandula abundance, light intensity and water temperature showed a negative correlation. Fisher’s exact test indicated that there was no relationship between the availability of Cryptocoryan sp. and the availability of P. bandula. Accordingly, moderately high pH, less light intensity and low water temperature appeared to be favoured by the P. bandula. The study outcomes can be used for the conservation of P. bandula and its restricted habitat in Sri Lanka.
Grossular-garnet bearing calc-silicate rocks from Kamburupitiya, southern highland complex, Sri Lanka: Implications for petrological signatures
(Postgraduate Institute of Science, University of Peradeniya, Sri Lanka, 2023-11-03) Sameera, K.A.G.; Fernando, G.W.A.R.; Dharmapriya, P.L.
Grossular, a Ca-garnet, is a key mineral found in calc-silicate rock in many granulite terranes, which provides important clues on P-T-fluid evolution. In Sri Lanka, grossular is mainly restricted to the southeastern, central Highland Complex (HC) and rarely found in southern and southwestern areas of HC. Here, we report the grossular bearing calc-silicate occurrence at Kamburupitiya, southern HC and its petrological signatures. Rock thin sections were prepared, and Electron Probe Microanalysis (EPMA) and documentation in Back Scattered Electron (BSE) image analysis were done during this study. Grossular occurs as either brown to reddish-brown gem quality massive coarse-grained mono-mineralic patchy or as medium- grained garnet associated with other platy minerals which form the predominant foliation of the rock. Petrologic observations and BSE images show the peak metamorphic assemblage consisting of grossular + clinopyroxene + scapolite + wollastonite ± calcite ± sphene. Grossular are highly fractured and frequently consist of scapolite + wollastonite inclusions without any breakdown reaction textures. Scapolite readily shows breakdown textures forming plagioclase + calcite + quartz symplectites via vapour absent reaction. Other minerals, including wollastonite, do not show any retrograde reaction textures; however, which are commonly recorded in other rocks in southwestern HC—mineral chemistry data of grossular shows Xᴳʳ⁻0.87 and homogeneous in composition from core to rim. The presence of a substantial amount of Fe with Cr and Mn in grossular is probably given its characteristic colour, mainly used as a gem quality hessonite. Scapolite, as well as symplectic plagioclase, are Na poor with equivalent anorthite of scapolite ~81 and anorthite content of plagioclase ~96%, which may indicate the absence of external alkali fluid infiltration as mainly recorded in calc-silicate rocks in southwestern HC during retrogression. Available phase equilibria suggest around 800 - 900 ⁰C at 8 kbar at the peak metamorphism. Scapolite + quartz + calcite symplectite developed at a later stage indicates isobaric cooling following peak metamorphism.
physico-chemical characteristics of inlet and outlet water in water treatment plants along the Mahaweli river between Kotmale and Victoria reservoirs
(Postgraduate Institute of Science, University of Peradeniya, Sri Lanka, 2023-11-03) Thilakarathna, P.T.A.; Fareed, F.; Makehelwela, M.; Premachandra, T.N.; Weragoda, S.K.; Karunaratne, S.H.P.P.
Mahaweli River, the longest river in Sri Lanka, delivers approximately 165,392 m⁻³ of drinking water daily to the Kandy district. The network of 14 major water treatment plants (WTPs) is positioned between Kotmale and Victoria reservoirs to extract water from the river. The river is notably contaminated due to industrialisation, rapid urbanisation, agriculture, and the discharge of domestic wastewater. The present study aimed to evaluate water quality by analysing physico-chemical parameters (pH, conductivity, dissolved solids, anions, and cations) at both inlets and outlets of the 14 WTPs. During September 2022 and February 2023, 58 water samples were collected and analysed following the methods prescribed by APHA. Concentrations of anions and cations were analysed using IC and ICP/MS, respectively. The maximum and minimum values of the measured parameters at both the inlets and outlets fell within the permissible limits recommended by NEA No.47 of 1980 and SLS 614:2013 guidelines, respectively. However, statistically significant disparities between the inlet and outlet water in NO₃⁻ , SO₄²⁻, F⁻ and Cl⁻ concentrations of two distinct seasons were observed. It was evident that the levels of pollutants, such as those originating from industrial (e.g., textile and laundry) waste discharge and agricultural and urban runoff, are more likely to escalate during the wet season. A significant variation was observed among water treatment plants within the same season due to inherent geological variations, anthropogenic activities, and diverse contaminating sources. Notably, the regions characterised by intense urbanisation between Paradeka and Balagolla exhibited higher contamination levels of anions and cations. In contrast, Nanuoya exhibited the most substantial contamination, primarily due to the effluent of Gregory Lake, Nuwara Eliya. Acquiring a comprehensive understanding of the variations in physico-chemical parameters along the Mahaweli River is vital for effective water management practices.
Prevalence of antibiotic resistance bacteria along the Mahaweli river segment between Kotagala and Balagolla
(Postgraduate Institute of Science, University of Peradeniya, Sri Lanka, 2023-11-03) Fareed, F.; Suganya, T.; Thilakarathna, P.T.A.; Jinadasa, R.; Premachandra, T.N.; Weragoda, S.K.; Karunaratne, S.H.P.P.
The release of antibiotics into the environment promotes the selection of Antibiotic Resistant Bacteria (ARB). The objective of the study was to analyse the prevalence of ARB at water inlets and outlets of selected Water Treatment Plants (WTPs) along the Mahaweli River in wet and dry seasons. Two visits were made to 14 WTPs operated by the National Water Supply and Drainage Board along the Mahaweli River between Kotagala and Balagolla in the wet (September 2022) and dry (February 2023) seasons to collect raw and treated water. The membrane filtration technique, using 1 ml of raw water and 100 ml of treated water, was used to separate Fecal Coliforms. Each location confirmed Escherichia coli colonies from routine biochemical tests were subjected to Antibiotic Susceptibility Test (AST) using six antibiotics (amoxicillin, ceftazidime, tetracycline, co-trimoxazole, streptomycin and ciprofloxacin) on Mueller Hinton agar medium. Statistical software, SPSS, was used to analyse the data. Escherichia coli was absent in all the treated water samples. Eighty-four colonies from both seasons were tested for AST. More than half of the tested colonies (61%) were resistant to at least one antibiotic. A significant seasonal change was observed only in amoxicillin resistance, being high in the wet season (29/35, 83%) and low in the dry season (22/49, 45%) (p=0.014). There were no significant seasonal changes in antibiotic resistance among locations (p=0.410). Multi-Drug Resistance (MDR) was observed at eight WTPs. Only Nawalapitiya and Paradeka WTPs showed MDR in both seasons. The study showed that the inlet water of the WTPs in the Mahaweli River is contaminated with ARB at most locations, as indicated by E. coli. The point contaminations play a major role in the accumulation of ARB rather than the season. Patterns of land use and antibiotic usage may act as key factors for this observation. A study on land use data is required to strengthen these findings further.
Urban bird diversity in selected locations of Colombo District and the attitudes of residents toward birds in their neighborhood
(Postgraduate Institute of Science, University of Peradeniya, 2023-11-03) Perera, K.K.A.; Gunaratne, A.M.T.A.
Urban green spaces offer many ecosystem services, emphasising the importance of evaluating urban biodiversity and urban community attitudes in planning these environments. This study investigated the avifaunal diversity in selected locations in the Colombo district and the attitudes of residents towards urban birds. Study sites were selected based on the level of urbanisation in different divisional secretariat divisions (DSD) (Kotte and Dehiwala DSDs as highly urbanised areas and Homagama and Padukka DSDs as moderately urbanised areas). A wetland and a woodland habitat from each DSD were sampled. Three-point transects along a single-line transect were surveyed to quantify avifauna, and a social survey was conducted among 115 inhabitants. A total of 78 bird species belonging to 42 bird families were recorded in the study areas during the study period. The species richness and diversity of birds were lower in urban than in suburban habitats. Most respondents (84.3%) observed birds in their neighbourhood, and most of them appreciated the small garden birds and water birds (93.04% and 86.95%, respectively). However, Corvus splendens (house crow) was noted by residents for their undesirable behaviour, such as making noisy calls and defecating on properties. Additionally, most respondents fed birds in their homes (83%), and female respondents were more involved in feeding birds compared to male respondents. Most of the respondents were interested in watching birds in their urban neighbourhood (53%) and watching documentaries about nature on television (47.8%). A relatively low percentage of residents (32.1%) reported issues with urban birds. However, 97.38% of respondents agreed with the statement, “Urban birds are important to maintain the natural balance in the city”. Since birds in the neighbourhood positively contribute to the people’s well-being, it is vital to use data on avifaunal diversity to plan and manage urban natural resources effectively.
A preliminary investigation on the quality of municipal compost produced in Kandy, Kurunegala and Mawanella
(Postgraduate Institute of Science, University of Peradeniya, Sri Lanka, 2023-11-03) Fernando, M.S.H.; Navaratne, A.N.
Municipal compost is a product derived from municipal solid waste. Local government authorities in Sri Lanka produce municipal compost as a part of their solid waste management program. The compost product is then marketed without a proper label that includes necessary information for the consumers on the packaging. Municipal solid waste is highly susceptible to contamination because of the non-segregation of waste. Thus, the safety and effectiveness of municipal compost is decidedly questionable. Five compost samples per composting facility were obtained from three separate municipal composting facilities located in Kandy, Kurunegala and Mawanella according to simple random sampling. The samples were air-dried and analysed for soluble nutrients extracted using a 0.01 mol dm⁻³ CaCl₂ solution. The orthophosphate molybdenum blue method was used to determine soluble phosphate, the cadmium reduction method was used to determine soluble nitrate, and AAS was used for the soluble magnesium ion detection. A 2 mol dm⁻³ KCl solution was used as the extractant, followed by the Indophenol blue method to measure soluble ammonium ions. Compost samples digested in aqua regia were analysed for the presence of heavy metals. Heavy metals, lead, chromium, and cadmium were measured using AAS. Although most measurements were within tolerable limits, the results indicate nitrate levels of more than ten times the expected value of 500 mg kg⁻¹ and cadmium content exceeding the 10 mg kg⁻¹ limit. Further, it was observed in all the compost samples that there was a significant presence of plastics along with other impurities. Non-segregation of waste material was observed in all three composting facilities. For future studies, sample count should be increased to minimise the variance. Further, incorporating a broader set of test parameters on par with international standards and microplastic analysis can better understand the municipal compost produced in Sri Lanka.
Preliminary study on diversity of lepidopterans in two distinct habitats in the Dunumadalawa forest reserve, Kandy, Sri Lanka
(Postgraduate Institute of Science, University of Peradeniya, Sri Lanka, 2023-11-03) Kodithuwakkuarachchi, C.D.; Weerakoon, K.C.; Hettiarachchi, T.R.K.
The present study investigated the diversity of lepidopterans (Class Insecta, Order Lepidoptera) at Dunumadalawa Forest Reserve, Kandy, a sub-montane forest in the wet zone of Sri Lanka. Sampling was done in two selected habitat types: a mixed forest habitat above the Rosnith Lake and a habitat dominated by the invasive Yakadamaran trees (Myroxylon balsamum). The study was conducted for one year, from February 2019 to March 2020. In each habitat, butterfly and moth species and their abundance were recorded while walking along a 50 m line transect extending 5 m on either side of the mid-line and a maximum of one hour at each transect. Five such transects were sampled from each habitat. Field identification of butterflies and moths was done using standard guides, and photographs were taken to document the species encountered. A total of 31 species, including six endemics belonging to 15 families, were recorded from the mixed forest, whereas 21 species with two endemics belonging to eight families were recorded from the habitat with Yakadamaran trees. The butterfly family Pieridae was dominant in the mixed forest habitat above the Rosnith Lake, while the moth family Erebidae dominated the Yakadamaran forest habitat throughout the study period. The Shannon diversity index (H′) of lepidopterans in the mixed forest habitat above the Rosnith Lake and in the Yakadamaran forest habitat were 2.53 and 1.33, respectively. Species evenness (E) was 0.77 in the mixed forest above the Rosnith Lake habitat and 0.44 in the Yakadamaran forest habitat. According to the Shannon diversity index, the mixed forest above the Rosnith Lake habitat had a higher diversity of butterflies and moths compared to the Yakadamaran forest habitat. Moreover, the lepidopteran species are more evenly distributed in mixed forest habitats compared to the Yakadamaran forest habitat. According to the study, habitat homogeneity and associated conditions directly influence the lepidopteran diversity.
Removal of lead (ii) from aqueous solutions by peels of banana variety available in Sri Lanka
(Postgraduate Institute of Science, University of Peradeniya, Sri Lanka, 2023-11-03) Perera, L.K.I.N.; Navaratne, A.N.
Lead (II) is a water pollutant released from industrial and agricultural activities to the environment. It is non-biodegradable and tends to bio-accumulate, which causes environmental contamination. This study investigated the removal of Pb (II) ions using peels of the Puwalu banana (Musa acuminata Colla), a banana variety available in Sri Lanka. Banana peels (BP) are waste material that could be used as an environmentally friendly adsorbent. The dried ground Puwalu BP were characterised by a Scanning Electron Microscope, which illustrated the surface morphology of the BP, and pattern of the Powder X-ray diffraction of the BP showed the amorphous nature of the adsorbent. Fourier Transform Infrared spectroscopy analysis was conducted for the BP before and after Pb (II) adsorption to determine the functional groups involved in removing Pb (II) ions. Parameters such as particle size, adsorbent dosage, contact time, and pH were optimised, and the concentrations of Pb (II) ion in solutions were determined using a Flame Atomic Absorption Spectrometer. Under optimal conditions, the maximum Pb (II) removal percentage was 87.19%. Langmuir and Freundlich isotherm models were applied to determine the adsorption behaviour between the metal ion and the adsorbent. Both isotherm models showed a correlation coefficient where R2 values were close to one (R2 ≈ 0.99), and the maximum adsorption capacity for Pb (II) was 11.42 mg g⁻¹. The present study suggests that ground Puwalu BP can be used as a cost effective adsorbent for removing Pb (II) ions from aqueous media.
Assessment of soil bacterial diversity in organic and conventional agroecosystems via high through put sequencing
(Postgraduate Institute of Science, University of Peradeniya, Sri Lanka, 2023-11-03) Tissera, B.D.; Ramanayake, M.K.; Mantilaka, M.M.G.P.G.; Herath, H.M.L.I.
Soil bacterial diversity is a vital regulator of fundamental ecosystem processes. Using synthetic inputs in agriculture alters the microbial community structure and its functional capacity. The alpha diversity of soil measures the species diversity within an ecosystem or area. The Chao1 diversity index measures species richness, and the Shannon diversity index measures species richness and evenness. High throughput sequencing (HTS) is an ideal way to gain information on microbial communities in heterogeneous environments such as soil. This research is intended to compare soil bacterial diversity in organic and conventional farms in different agroecological zones of Sri Lanka by accessing soil metagenome. To this end, the metagenomic sequencing data of the V4 region of the bacterial 16S rDNA extracted from six organic and conventional agricultural lands located in Nuwara Eliya, Mawathagama, and Labuduwa (Wet zone), Makandura and Padiyathalawa (Intermediate zone) and Maha Illuppallama (Dry zone) of Sri Lanka were analysed using the QIIME2 2022.2 (Quantitative Insights into Microbial Ecology) pipeline. Samples were rarefied at a sequencing depth of 15,000, and the alpha diversities (Chao1 and Shannon) were calculated. The Chao1 diversity of the organic fields in Nuwara Eliya, Mawathagama, Labuduwa, Makandura, Padiyathalawa and Maha Illuppallama were 1397.17, 659.37, 594.67, 1025.50, 814.08 and 733.94 respectively and Chao1 diversity of the respective conventional fields were 592.47, 357.83, 1030.51, 762.02, 666.47 and 568.00. The Shannon diversity of the organic fields in Nuwara Eliya, Mawathagama, Labuduwa, Makandura, Padiyathalawa and Maha Illuppallama were 9.13, 8.57, 8.32, 9.20, 8.62 and 8.43 respectively and the Shannon diversity of respective conventional fields were 8.55, 7.72, 8.95, 8.51, 8.49 and 8.22. Except for the farm in Labuduwa, the results showed that organic farms had higher Chao1 and Shannon diversity. Thus, this study suggests that organically cultivated agricultural fields may have more alpha diversity than conventionally cultivated fields.
Adsorption of lead (ii) ions on magnetite/magnesium oxide nanocomposites
(Postgraduate Institute of Science, University of Peradeniya, Sri Lanka, 2023-11-03) Ishra, M.I.; Gurunanthanan,V.; Wijayaratne, K.B.; Dassanayake, B.S.; Perera, H.C.S.
The effective removal of heavy metal ions, particularly lead(II) [Pb(II)], from contaminated water sources remains a pressing environmental concern. This study explores the potential of magnetite/magnesium oxide (Fe₃O₄/MgO) nanocomposites as an efficient adsorbent for selective Pb(II) removal. The Fe₃O₄/MgO nanocomposites were synthesised using a controlled sol-gel method and characterised using various techniques. XRD analysis confirmed the presence of cubic MgO and cubic Fe₃O₄. Pb(II) adsorption induced a crystallographic transformation, forming hexagonal Mg(OH)2 crystals, indicating interaction with the adsorbent. SEM analysis revealed rod-like and spongy spherical morphologies. Rod-like structures provided a larger surface area and active sites for effective Pb(II) interaction, while spongy spherical particles, representing magnetic Fe3O4, contributed to stability and dispersibility. EDS analysis showed Fe, O, and Mg presence with weight percentages of 28.97%, 25.55%, and 30.0%, respectively. VSM results confirmed superparamagnetic behavior with a saturation magnetisation of 32.02 emu g⁻¹, indicating potential for magnetic separation and recovery in various wastewater treatment applications. Adsorption experiments utilised optimised conditions: initial concentration of 600 mg L⁻¹ adsorbent dosage of 0.25 g L⁻¹, pH of 7, and 120 minutes reaction time. Fe₃O₄/MgO nanocomposites exhibited exceptional performance with a remarkable 99.98% removal efficiency and a high adsorption capacity of 2399.44 mg g⁻¹. These impressive results underscore the outstanding adsorption potential of the nanocomposites. Adsorption kinetics followed the pseudo-second-order model (R2 = 0.99), confirming suitability for Pb(II) removal. The Freundlich model indicated a heterogeneous surface with different adsorption sites. These comprehensive findings support efficient Pb(II) removal using Fe₃O₄/MgO nanocomposites, paving the way for advanced adsorption strategies in water treatment. Overall, Fe₃O₄/MgO nanocomposites exhibit potential as a cost-effective, environmentally friendly adsorbent for removing Pb(II) ions, providing a promising water purification and environmental remediation solution.
Changes in water consumption patterns post-installation of reverse osmosis water treatment plants in Dimbulagala, Sri Lanka
(Postgraduate Institute of Science, University of Peradeniya, Sri Lanka, 2023-11-03) Bandara, T.; Witharana, A
Installing Reverse Osmosis (RO) water treatment plants is seen as a solution to provide safe drinking water to areas in Sri Lanka affected by chronic kidney disease of unknown etiology(CKDu). The current study intends to identify changes in water consumption patterns post- installation of RO plants in the Dimbulagala divisional secretariat division, considered one of the CKDu prevalent areas in Sri Lanka. In the present study, a questionnaire survey was carried out on 154 households to get the perspectives on the quality of drinking water: palatability and appearance. In addition, accessibility to the water source was determined by considering the travel time. The findings revealed that 52% of the population agreed that they had palatable drinking water before installing RO units. In addition, 86% of the sample population agreed that the drinking water had a clear appearance. With the commissioning of RO units, the water usage from other sources has been reduced over the period between 2010 - 2022 (tap water 6%, rainwater 4%, well water 18%, surface water 12% and bottled water 2%). About 28% of the population has rejected RO-treated water due to non-disclosed reasons. While 28% of the total population have access to RO water from their premises, 26% travel more than 15 minutes to access RO water. However, 66% of the total population was satisfied with the water availability and the quality post-installation of RO units. Lack of awareness of health concerns related to contaminated groundwater consumption, financial constraints, distance to access the RO plant and differences in palatability were the main reasons which prevented the consumption of RO-treated water. Therefore, the need for adequate knowledge transfer to the community on RO technology is warranted.
Evaluation of different substrates for hydrolysis and subsequent methanogenesis in the anaerobic reactor
(Postgraduate Institute of Science, University of Peradeniya, 2023-11-03) Jayalath, J.M.S.; Witharana,A.; Sirisena, K.K.A.; Dharmarathne, H.A.S.G.
Anaerobic digestion is essentially a procedure that turns organic substrates into biogas, which serves as a renewable energy source. In this digestion process, different substrates are utilised for degradation. Biogas production is governed by four digestion stages of substrates: hydrolysis, acidogenesis, acetogenesis, and methanogenesis. Biogas production is prominent at the latter stage of the digestion process of the substrate in the anaerobic reactor. The time taken to initial degradation (hydrolysis, acidogenesis, acetogenesis) of the substrate can vary from a few days to several weeks. However, the effect of the substrate to move forward from the lag phase (hydrolysis, acidogenesis, acetogenesis) to the log phase (methanogenesis) has limited understanding. Therefore, the present study was carried out to determine the effect of substrate composition on subsequent methanogenesis in the anaerobic reactor. Cow dung was used as the base substrate. The base substrate was co-digested with four different substrate types: Gliricidia, kitchen waste, banana peels fermented in sugar, and a mixture of the above three substrates in 650 ml reactors. As a control, one reactor was kept only with cow dung. The reactor with a mixture of all substrate types exhibited a pH drop from 8 to 4 in 3 days, which witnessed accelerated hydrolysis (acid fermentation) and decomposition, while the other substrate combinations took more than 6 days to drop the pH from 8 to 4. Moreover, it was found that the reactor with the mixture of substrates showed the highest gas volume and flame time. Cow dung, kitchen waste, Gliricidia, and Banana peels fermented in a sugar substrate mixture can be identified as a substrate combination that effectively performs hydrolysis and subsequent methanogenesis. It can be concluded that the selection of substrate combinations for co-digestion significantly impacts biogas production to reduce the lag phase and increase the efficiency of the log phase.
The ancient tank construction technology in North Central dry zone of Sri Lanka: A hydro-ecological assessment
(Postgraduate Institute of Science, University of Peradeniya, 2023-11-03) Goonathilake, M.D.S.W.; Perera, M.P.
The ancient civilisation of Sri Lanka is known as a “hydraulic civilisation” due to the advanced water management practices associated with the tank irrigation heritages of ancient Sri Lankans. Ancient people selected the dry zone for their settlement by considering the availability of suitable natural and physical resources for agriculture. Tanks were constructed to store water for agriculture even in periods with minimum rainfall throughout the dry zone. Historical records indicated from the 3ʳᵈ century B.C., that tanks have been built by constructing an earth dam, across a valley, employing technical devices such as sluices, canals, and spillways. Although there are several studies on irrigation technology, sufficient attention has not been paid to analysing the hydrological and ecological dimensions of these techniques. The objective of this study is to make an attempt to fill this gap of knowledge. For this purpose, data were collected basically from literature citing Journal articles,scholarly work, google images, and institutional reports in addition to field verifications. In- depth field studies were conducted covering two large tanks, two medium and six small tanksselected from the North Central Province. Further, structured interviews were conducted with senior farmers and key local officers to understand the significance of hydro-ecological features. The study revealed that sluice technology, including besokotuwa and sluice front ridge, spill and outside spill, kulu-wewa system, and the cascading nature exemplify specific hydrological requirements. Some ecological devices, such as tank reservations and olagam- wewa system, were linked with the sustainability of irrigation tanks. These ecological devices have also contributed to purifying water and ensuring sustainability. Further, these techniques also contributed to wildlife impact management strategies in the dry zone of Sri Lanka. The findings of this study reflect that ancient tank construction technology and devices performed significant technical roles in hydrological and ecological management.
Carbon footprint of selected Sri Lankan tea industries
(Postgraduate Institute of Science, University of Peradeniya, 2023-11-03) Bandara, T.; Witharana, A.
Tea production has significant effects on the environment, including habitat conversion, reduction in biodiversity and ecosystem function, high energy consumption, and high use of pesticides and fertiliser. The impact of the tea industry on climate change and the best mitigation measures are still up for debate. This study was conducted to identify the parameters to quantify the greenhouse gas emission associated with fertiliser, material and energy usage in the tea sector in Sri Lanka and calculate the estimated value for Greenhouse Gas (GHG) emission in the tea sector. The Life Cycle Analysis (LCA) approach was used to estimate the carbon footprint across the life cycle of goods and services, including GHG emissions and other environmental impacts. Emissions were calculated based on resource consumption for the main processes in the tea life cycle in two major tea-producing companies from April 2019 to March 2020 in Sri Lanka, and total emissions were calculated using the average carbon footprint per 1 kg of tea and total tea production in Sri Lanka. Agrochemical application (>55%) is recognised as a major carbon-emitting activity in the tea manufacturing process. Water boiling is the highest carbon-emitting and high energy-consuming activity in the consumption phase. In the Sri Lankan context, tea consumption accounts for 66% of the overall carbon footprint, whereas tea manufacturing accounts for 34% of total GHG emissions per cup of tea. However, the overall estimated carbon footprint of tea production (cradle to gate) is 812,857 tCO₂e (51% of total), and the carbon footprint for local consumption is 784,788.76 tCO₂e (49% of total carbon footprint), and the estimated total carbon footprint (cradle to grave) for Sri Lankan tea sector is 1,597,646.26 tCO₂e per year.
Preliminary chemical investigation of two brown marine algal species in Sri Lanka
(Postgraduate Institute of Science, University of Peradeniya, 2023-11-03) Ramaraj, N.; Marapana, U.; Thiripuranathar,G.; Attanayake,K.; Ekanayake,S.
Brown marine algae are currently of great interest due to their abundance of bioactive compounds that can be used for several therapeutic and other applications. About 320 species of marine algae belonging to different families have been identified along the coast of Sri Lanka. In the present study, brown marine algal species Sargassum polycystum and Turbinaria ornata found in the Jaffna coastal area were studied for their phytochemicals, functional groups, minerals and fatty acid profile with standard assays. Aqueous algal extracts for the phytochemical screening were prepared by mixing dried, powdered samples in distilled water (1:10 w/v) followed by sequential extraction for 24 hours, while dried powdered samples were used for functional group analysis by FTIR and mineral content by ICP-MS. The fatty acid profile was analysed by direct transesterification of fatty acids followed by GCMS. Phytochemical screening results revealed the presence of reducing sugars, saponins, glycosides, triterpenoids, tannins, phenols, and alkaloids in both algal species. FTIR analysis indicated the presence of functional groups corresponding to alkaloids, amino acids, polysaccharides such as pectins and polymers such as lignins and cutins. Both algal species contained calcium, potassium, sodium, copper, iron and zinc. Trace amounts of heavy metals chromium, nickel, arsenic, mercury and lead were detected in both dried and powdered samples. Sargassum polycystum had the highest calcium content (6.8% dry weight [DW]), while T. ornata contained the highest potassium (7.2% DW). Both algal dried powders are good sources of iron due to their relatively high content (881 mg/kg S. polycystum and 583 mg/kg T. ornata DW). Pentadecanoic acid and hexadecanoic acid (palmitic) were the most prevalent fatty acids present in S. polycystum (50%) and T. ornata (38%). According to the results of the present study, both algae are good sources of bioactive compounds, essential minerals and bioactive fatty acids.
Does the environmental score of ESG (environmental, social, and governance) reporting have an effect on corporate performance of companies?
(Postgraduate Institute of Science, University of Peradeniya, 2023-11-03) Liyanage, S.I.M.; Pallewatta, N.; Jayathilake, R.; Hewavithana, N.
Integrating environmental, social, and governance (ESG) factors into investment decision- making has gained momentum in recent years, causing companies (mostly large-scale) to acquire and disclose the sustainability in ESG form in reporting. Out of all three aspects of ESG, environmental reporting is crucial since it gives insights into measures taken to address serious industrial environmental aspects. However, there are individuals questioning the requirement of environmental reporting. Therefore, the objective of this study is to measure the relationship between the Environmental score of ESG performance against the corporate performance of publicly listed companies in Sri Lanka, using the list of 128 companies for the year 2020. The data collection of the study was done through annual reports to quantify the qualitative ESG data using the Refinitiv methodology of ESG quantification as the independent variable. The two dependent variables to measure corporate performance are return on equity (ROE) and return on assets (ROA), collected through the same annual reports. The statistical analysis includes scatter plots, regression analysis and residual analysis to measure the significance of the relationship. However, the results of this study show no significant relationship between environmental score with both ROE and ROA. It concludes no relationship with corporate performance for the year 2020. Therefore, this study does not communicate the need for any environmental information reporting to improve the corporate performance of the companies. The limitations of conducting for the year 2020, a year with the pandemic, can directly impact the results. Furthermore, reasons may include greenwashing and the unsuitability of Refinitiv methodology for the Sri Lankan context.
Potential for promoting avitourism in Nanthikadal lagoon, Mullaitivu, Sri Lanka
(Postgraduate Institute of Science, University of Peradeniya, 2023-11-03) Samarakoon, S.M.N.; Wijesundara, C.
Avitourism plays a major role in wildlife tourism, contributing significantly to ecotourism. It has the potential to integrate sustainable development with wildlife conservation. The present study focused on the use of bird diversity for promoting ecotourism, specifically avitourism, in a selected area in Mullaitivu District, which consists of a unique geographical landscape including four lagoons, 208 freshwater tanks, a dense forest, and a 78 km stretch of coastline. All these resources give good opportunities for bird diversity, bird habitats, and potential for avitourism. In addition, the presence of infrastructure facilities such as road networks help promote avitourism within the study area. The point count method was utilized for estimating the bird diversity in the area. Sampling was conducted at nine selected points, encompassing three habitat types around Nanthikadal Lagoon. During the study period, 79 bird species belonging to 35 families were identified. Waterbirds were the dominant group observed, and among them, 26 species were migrants. According to the global/national conservation status, 10 species were Near Threatened (NT) and 3 were endemic. The forest area had the highest bird diversity (Shannon Index: 3.985), followed by shrub land (3.919) and marshy area (3.694). The present study also explored the potential for promoting avitourism, knowledge generation on bird diversity, and bird conservation. The Mullaitivu region not only holds avitourism potential, but also becomes a prime destination for ornithological studies, particularly in the realm of avitourism. It will simultaneously complement and enhance many other existing options for ecotourism.

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