iPURSE 2015
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- ItemSpatial variability of organic carbon desnity in cashew cultivated red latosol soils of Sri Lanka(University of Peradeniya, Sri Lanka, 2015-11) Wickramasinghe, W.M.K.M.; Karunaratne, S.B.; Gajanayake, B.; Abeysinghe, D.C.Soils contribute to regulate major biochemical cycles and in case of carbon (C) cycle it plays a vital role. In fact soil act as the largest terrestrial pool of C. Therefore, much attention is given to quantification of below ground C stocks or densities and uses this information for long term monitoring of C sequestration potential. In this study, an attempt was made to quantify the spatial variability and subsequently map (predict) the soil organic carbon (SOC) densities under cashew grown in Red Latosol soils. For this, a sub set of 22 ha was selected from the cashew seed garden in Elluwankulama, Puttalam district managed by Sri Lanka Cashew Corporation. A design- based sampling scheme namely stratified random sampling was adopted in this study. The stratification was carried out using compact geographic stratification (based on coordinates) with the aid of k-means clustering algorithm and the study area was divided into five strata. Total of 100 sampling locations were sampled where 20 sampling locations were allocated to each stratum. For all sampled locations, SOC density was calculated. In calculating of SOC density, a pedotransfer function (PTF) was used to predict the bulk density for sampling locations which did not measure bulk density in the field. Geostatistical approach was used to create higher resolution digital soil map of SOC density across the study site. Both PTF predicted bulk density values and geostatistical models were validated and statistically assessed using mean error (ME) and root mean square error (RMSE) indices. Summary statistics revealed that mean SOC %, bulk density and SOC density reported as 0.96 % (±0.21), 1.43 gcm-3 (±0.03) and 4.12 (±0.82), respectively. Results revealed that the bulk density values predicted by PTF reported ME of 0.0041 gcm-3 and RMSE of 0.0044 gcm-3 values for Red Latosols in the study site. The optimum spatial model for SOC density was identified as spherical model which reported lowest RMSE (0.769 ) and ME (0.00084 ) values. The nugget-to-sill ratio showed a moderate spatial dependence for SOC density (0.43). Furthermore, results revealed that spatial auto-correlation (range parameter) of SOC density goes up to 82 m. This indicates that in future sampling of Red Latosols in order to characterize the spatial variability of SOC density, sampling interval should be maintained within 82 m. Predicted SOC density over the study area reported a mean value of 4.14 (±0.34) while 3.95 and 4.34 for quantiles one and third, respectively. Results further revealed that majority of the land extent (13.4 ha) in the study site reported SOC density in between 4.0 to 4.5 . The information generated in this study could be useful in national carbon accounting programs, carbon credit programs and for site specific fertilizer application.
- ItemAwareness and distribution of Invasive alien species (ias) of flora in galigamuwa area(University of Peradeniya, Sri Lanka, 2015-11-06) Warunasinghe,W.A.A.I.Biological invasions happen either deliberately or accidentally and are considered as serious threats to the biodiversity and its irreversible impact to the biodiversity is second only to the habitat loss. Thirty common IAS of plants were selected and the study inquired whether the local people were well aware about IAS of flora and if so, whether these species have badly influenced the environment and farming activities and its distribution in Galigamuwa area. Primary data were collected through a pretested self-administered questionnaire and 65 households were selected by using Multi stage random sampling technique. Analysis was carried out based on descriptive statistics together with graphical interpretation. According to the depicted results, all the respondents (100%) were aware about IAS of flora. Majority of the respondents (46%) educated through newspapers. Only few respondents (6%) were aware about Guinea grass (Panicum maximum), one of the prominent IAS of flora in Sri Lanka. Moreover, very few respondents were aware about Rila Thana (Pennisetum polystachion) 2% , Wal Sudda (Austroeupatorium inulifolium) 12%, Mist flower (Ageratina riparia) 3%, Gal Goraka (Clusia rosea) 7%, welvet tree (Miconia calvescens) 6%, Kikiyu grass (Pennisetum clandestinum) 2%, Parthenium (Parthenium hysterophorus) 12%, Kattakumanjal (Myroxylon balsamum) 8%, Yellow cestrum (Cestrum aurantiacum) 3%, Blue stars (Aristea ecklonii) 2% and Arunadevi (Sphagneticola trilobata) 2%. According to the depicted results, respondents have not observed Kikiyu grass (Pennisetum clandestinum) and Rila Thana (Pennisetum polystachion) in their surroundings. Moreover, no respondents (0%) were aware about Gorse (Ulex europaes). Results revealed that, majority of the respondents have seen water hyacinth (Eichhornia crassipes) 69%, salvinia (Salvinia molesta) 54%, Katu pathok (Opuntia dilenii) 57%, Katakalu Bovitiya (Melastoma hirtum) 60%, Wathupalu (Mikania micrantha) 72%, Mahogani (Swietenia macrophylla) 74%, Lantana (Lantana camara) 55%, Podisingnomaran 62% in their surrounding environments. While 69% of the respondents were aware about pinus (Pinus caribaena), only 25% of them have seen pinus in their surroundings. Of the sample, majority of the respondents were aware about Ginikuuru Gas (Alstonia macrophylla) 51%, Wild sunflower (Tithonia diversifolia) 58%, Para (Dillenia suffruticosa) 58% and Yoda nidikumba (Mimosa pigra). Very few of the respondents were aware about Katu Andara (Prospis juliflora) 35%, cuscuta (Cuscuta compestris) 40%, Kadadasi Mal (Antigonon leptopus) and Cheena Pera (Psidium littorale) 25%. Of the sample, majority of the respondents (58%) were facing difficulties in their day to day lives due to IAS of flora and most of them (52%) try to control these plants. Majority of the respondents (43%) have observed the reduction of native plant species due to IAS of flora and 37% of the respondents do not have clear idea about the adverse impacts of IAS of flora. According to the results, 45% of the respondents have reported that IAS flora have badly affected to their aquatic environments.
- ItemSelenium in rice (Oryza sativa) from different geographic and climatic regions of Sri Lanka(University of Peradeniya, Sri Lanka, 2015-11-06) Diyabalanage, S.; Navarathna, T.; Chandrajith, R.Rice is the main staple food in Sri Lanka as in many other Asian countries. It has been identified that people who consume rice as a staple food are inevitably exposed to significant amounts of different trace elements. Among these trace elements, selenium (Se) is one of the least known, but essential element for both humans and animals. Deficiency of Se can increase the susceptibility of the kidney’s to oxidative damage, but Se becomes toxic to humans when the intake exceeds 900 μg/kg per day. Availability of Se and other bio-important trace elements in rice from Wet Zone (WZ), Dry Zone (DZ) and Intermediate Zone (IZ) were investigated in this study. Concentrations of 19 trace elements in 200 rice samples, including improved (n=188) and traditional rice varieties (n=12) were measured with Inductively Coupled Plasma Mass Spectrometry (ICP-MS) after microwave aided acid digestion. The Se contents in improved rice varieties ranged from 0.03 to 261 μg/kg with mean values of 35.4 μg/kg, 42.8 μg/kg and 22.1 μg/kg for WZ, DZ and IZ, respectively. Comparatively higher Se levels were recorded in white polished rice varieties from the DZ and IZ than brown rice varieties from the same regions. Comparatively higher Se levels were observed in traditional rice varieties that varied from 77.51 to 163.8 μg/kg with the mean of 116.4 μg/kg. Among them, the highest Se content was reported in “Maa Vee”, which is widely recommended for diabetes, tuberculosis, constipation, hemorrhoids and cardiovascular diseases in traditional medicine. Based on the average daily consumption of rice by a person, the total daily intake (TDI) of Se was calculated. The TDI are 10.04 μg, 12.14 μg and 6.26 μg from rice of WZ, DZ and IZ, respectively. Results of the study also demonstrate that the Se concentration does not vary significantly among climatic zones. Though Se is available in other foods such as garlic and other vegetables, the recorded values for Se in rice are far below the recommended daily Se intake. Although some early studies indicated higher arsenic (As) contents in Sri Lankan rice, this study reveals that it is well below the Codex Alimentarius recommended maximum allowable limit.
- ItemInteraction of ferrous ions and free chlorine on microbiological quality of drinking water(University of Peradeniya, Sri Lanka, 2015-11-06) Munasinghe, T.S.; Abayasekara, C.L.; Chandrajith, R.; Jayawardana, A.University of Peradeniya has a nearly 60 year’s old water distribution network that consists mainly iron pipelines, most of which are now corroded to a large extent, adding iron rust to water. The aim of this study was therefore to investigate the possible consumption of free chlorine that added in to water for disinfection by iron dissolved from pipes. If free chlorine is reduced due to iron, the available amount of free chlorine would not be sufficient for the disinfection of microorganisms in water. A laboratory simulated study was carried out to investigate the possible reaction between ferrous ion and free chlorine in water using a series of and free chlorine mixtures. The effect of the reaction on the inhibition of microorganisms were also determined by spiking Serratia spp. (a total coliform) and Escherichia coli (a fecal coliform) into known mixtures of and free chlorine. The and free chlorine contents were measured spectrophotometerically while viable microbial count was assessed using membrane filtration technique that followed a confirmation tests. Furthermore free chlorine and microbiological quality were determined periodically using 27 water samples that were collected from various points of the University network. The results of this study indicated a rapid reaction between and free chlorine. The rate of free chlorine reduction was directly proportional to the amount of in water. Although inhibition of Serratia spp. and E. coli was observed due to free chlorine in water, the effect reduced drastically with increasing in water. Serratia sp. decreased gradually with the ascending chlorine levels at levels of 0.2 and 1.0 mg/L. Total inhibition of Serratia sp. were observed at 2 and 3 mg/L of while E. coli was inhibited at levels of 1.0, 2.0 and 3.0 mg/L. The content in the water distribution network of University of Peradeniya were ranged from <0.01 mg/L to 0.64 mg/L (desired value is <0.3 mg/L), while the desired free chlorine level (0.2 mg/L) was observed only at two locations (Faculty of Veterinary Science and Meewathura treatment plant). Total coliforms were detected in samples collected from Upper Hanthana, Marcus Fernando Hall, University Temple, Science Faculty, Mars Hall and Medical Faculty, while fecal coliforms were detected only in a sample from Marcus Fernando Hall. The results of microbiological test showed that water distributed from the Kandy Municipal Council and Meewathura plants are suitable for drinking, but water distributed from the Upper Hanthana plant was not suitable for human consumption according to the World Health Organization (WHO) Standards (0/CFU per 100 ml for both total and fecal coliforms) and Sri Lankan Standards (3/CFU per 100 ml for total coliforms and 0/CFU per 100 ml for fecal coliforms). The possible reason behind the unsuitable microbiological quality of water may be related to the reaction between and free chlorine in water. It was also noted that, a high level of in water was inhibitory to microorganisms in water and remove bacteria by formation of clumps.
- ItemFluoride uptake by native and modified cattle bones from aqueous medium by batch adsorption(University of Peradeniya, Sri Lanka, 2015-11-06) Gunathilake, B.A.P.T.; Iqbal, M.C.M.; Sumanasinghe, V.A.Fluoride is found in excess compared to the WHO recommended levels in drinking water in the Kandy district. Health hazards such as dental fluorosis, skeletal fluorosis, crippling fluorosis and metabolic defects in lipids, proteins and vitamins are caused due to excess Fin drinking water. Among several defluoridation techniques, adsorption is the most effective and common method. The objective of this study was to investigate the effectiveness of the natural, economically feasible and eco-friendly materials such as plant leaves and cattle bones for removing fluoride ion from drinking water using batch adsorption method. Bio-adsorbent materials were collected and rinsed initially with tap water, and then with deionized water. Cleaned materials were air dried for 48 h and oven dried at for 48 h. Dried materials were sieved to obtain particle size between 250 – 350 μm. Batch adsorption experiments were conducted. A mass of 0.2 g of different adsorbents was added in 50 mL of 3 mg fluoride solution and shaken at 80 rpm in orbital shaker for 3 h. Thereafter, suspension was filtered and final Fconcentration was determined by fluoride ion-selective electrode. Chemical and physical modifications such as base treatment and bone char preparation were done to enhance the adsorption efficacy. Native bones were heated at 500oC for 3 h in muffle furnace to prepare bone char (BC). Effect of contact time and dosage were determined for chemical modification and effect of pH, kinetic studies, isotherm studies, desorption and adsorbent characterization for BC were carried out. adsorption on BC was maximum between pH 4-7 and equilibrium time for BC was 12 h. Pseudo second order kinetic model and Langmuir isotherm model described adsorption of on BC. The highest desorption was given with 0.1 M NaOH. BC enhances the efficacy of defluoridation from aqueous medium and is a cost effective and eco-friendly biosorbent.
- ItemImpacts of sea level rise and bed level accretion on residence time of Negombo lagoon, Sri Lanka(University of Peradeniya, Sri Lanka, 2015-11-06) Pushpakumara, P.K.P.; Nandalal, K.D.W.; Weerakoon, S.B.Water quality of an aquatic system is highly influenced by residence time (RT), which indicates how long a constituent is retained inside the system. This paper focuses on the effect of climate change induced future sea level rise (SLR) and associated bed level variations on RT of Negombo lagoon, Sri Lanka. The hydrodynamic behaviour of the lagoon was numerically simulated using Delft3D surface water modelling suite. The time required to drop the concentration of a constituent to of its original value was calculated as the RT of the lagoon. Anticipated maximum SLR of 79 cm at the end of the 21st century, predicted by the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, was considered as the future sea level of the lagoon. Three bed level accretion conditions, namely, no bed level accretion, accretion of the lagoon bed level by 50% of the SLR (partial bed level accretion condition) and accretion of the lagoon bed level similar to the SLR (full bed level accretion condition), in response to the anticipated SLR were considered. RT was calculated for each bed level variation under low (5.64 ) and high (41.93 ) streamflow conditions. Model predicted RTs of the lagoon at present are 22.4 days and 12.4 days under low and high streamflow conditions, respectively. Under the absence of bed level accretion, RT is increased up to 32.2 days (+43.7%) and 17.8 days (+43.5%) due to SLR in low and high streamflow periods, respectively. Under partial bed level accretion, RT is decreased up to 18.1 days (-19.2%) and 12 days (-3.2%) in low and high streamflow periods, respectively. RT is decreased up to 13.4 days (-40.2%) and 8.5 days (-31.5%), under full bed level accretion, in low and high streamflow periods, respectively. The results reveal that the climate change induced future SLR and the associated bed level accretion influence the RT of the lagoon altering the lagoon water quality.
- ItemP-T-t Evolution of calc-silicate rocks in the South-Western highland complex of Sri Lanka(University of Peradeniya, Sri Lanka, 2015-11-06) Sameera, K.A.G.; Perera, L.R.K.Recent studies on calc-silicate rocks from the Southwestern Highland Complex of Sri Lanka have renewed the interest on the reconstruction of the P-T-t and fluid evolution in this part of the island. Present study is another contribution to understand the P-T-t path and fluid conditions of the calc-silicate lithologies around Galle and Middeniya-Embilipitiya areas in the Southwest. Based on petrography and mineral assemblages, the studied calc-silicate lithologies can be subdivided into three main groups; Group I – wollastonite-bearing but grossularite-absent assemblages, Group II – grossularite-bearing but wollastonite-absent assemblages, Group III - both wollastonite and grossularite-absent assemblages. Formation of different assemblages is possibly a result of peak metamorphic P, T conditions, the chemistry of protoliths, graphite precipitation and response to fluctuation of level during prograde path. Critical reaction textures in Group I lithologies indicate breakdown of, (1) wollastonite calcite + quartz, (2) wollastonite + dolomite → calcite + diopside, (3) scapolite → calcite + quartz + plagioclase, (4) alkali feldspar + wollastonite → scapolite + quartz + K+, that are important in re-constructing the P-T-t evolution of the terrain. Diopside rims around quartz in Group II assemblage suggest the reaction, (5) dolomite + quartz → diopside + CO2. In addition, local occurrences of fluids involving reaction textures such as myrmekitic intergrowth of plagioclase + quartz between calcite + K-feldspar and replacement of diopside by hornblende have been observed in calc-silicate rocks from the study area. Peak metamorphic assemblage of the Group I suggests a stabilization temperature of about 800-8500C at 5 kbar, and 0.2 in the fluid phase. The retrograde reactions (1), (2) and (3) suggest isobaric cooling (IBC) following peak metamorphism during which internal fluid buffering prevailed. But the IBC reaction anorthite + wollastonite → grossularite + quartz, noted from elsewhere was not present in the studied samples perhaps due to lower lithostatic pressure in the study area. The reactions (4) and (5) suggest isothermal decompression (ITD) following the IBC path, and other fluid involving reactions noted in the study area suggest both hydration and influx during final stages of metamorphic evolution. The retrograde reaction textures in the studied calc-silicates and the inferred IBC and ITD P-T-t segments for the Southwestern Highland Complex correlate well with the results of previous P-T-t studies of calc-silicate, pelitic and mafic rocks in the Highland Complex. Further, presence of grossularite-absent assemblages, the reaction textures (1), (3) and (4), and the inferred P-T-t path for the study area strongly correlate well with mineral assemblages, reaction textures and P-T- t evolution in the Kerala Khondalite Belt within the Trivandrum Block of Southern India.
- ItemSpatial variability of soil properties in a calcic red latosol soil scape in the nothern area of Sri Lanka(University of Peradeniya, Sri Lanka, 2015-11-06) Nerogini, S.; Vitharana, U.W.A.; Karunainathan, T.The information on the spatial variability of soil properties is vital for the better management of soil and to increase the crop productivity. This study was conducted to explore the short-scale spatial variability of selected chemical and physical soil properties of a Calcic Red Latosol soil scape in the Alaveddi area in the Jaffna district. The study area consisted of 2.5 ha and samples were collected within the plough depth (0- 30 cm) by using stratified random sampling scheme. This was achieved by firstly defining a sampling (spacing 29 x 29 m) grid. Subsequently, a random sample was added within each grid cell. The variability of soil clay content, silt content, sand content, organic matter (OM), pH (soil to water ratio of 1:2.5) , electrical conductivity (EC) (soil to water ratio of 1:5) were investigated for all the samples (n=40) and available phosphorous, exchangeable potassium were investigated for selected samples (n=9) by means of classical and geo statistical analysis techniques. The coefficient of variation of properties ranged from 4% (pH) to 32% (clay content). The experimental variograms calculated for soil properties were best fitted with spherical model. According to the relative nugget effect (RNE -ratio of nugget to the sill) of variograms, the clay content, sand content, silt content, electrical conductivity and organic matter exhibited a highly spatially structured variability (RNE < 25 %), whereas a medium structured variability was observed for soil pH (RNE 25-75 %). The observed spatial dependencies of soil properties indicated that sampling space for future studies can be ranged from 20 m (pH) to 70 m (sand). The maps of texture, OM further illustrated a strong short-scale spatial variability indicating the potential of site-specific soil management in the study area.