International Research Symposium on Pure and Applied Sciences (IRSPAS)

Permanent URI for this communityhttp://repository.kln.ac.lk/handle/123456789/15650

Browse

Author: search.filters.author.Manage, P.M.Subject: search.filters.subject.Solid-phase micro extraction

Search Results

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Cyanobacteria and 2-Methylisoborneol: the influence of Nitrogen and Phosphorous
    (4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Ganegoda, S. S.; Chinthaka, S. D. M.; Manage, P.M.
    2-Methylisoborneol (2-MIB) is a key compound, which causes taste and odour (T&O) issues in water. Despite of no recorded health hazards reported associated with 2-MIB, water consumers reject the water with 2-MIB due to its unpleasant musty (moldy) T&O. The aim of this study was to study the correlation between cyanobacteria abundance, 2-MIB levels coupled with Nitrogen and Phosphorous levels. 2-MIB contamination level in sixteen raw water bodies, which are being used for drinking in six districts (Anuradhapura, Pollonnaruwa, Ampara, Batticaloa, Trincomalee and Hambanthota) were analyzed using Gas Chromatography–Mass Spectrometry coupled with Solid-phase micro extraction. Enumeration and identification of cyanobacteria was carried out using standard microscopic methods. Anabaena, Microcystis, Oscillatoria, and Cylindrospermopsis species were identified as the most abundant cyanobacteria. 2-MIB levels ranged from 5.3 ± 0.94 to 139.4 ± 0.21 ppt throughout the dry season of the sampling period, where the highest level was recorded in Kondawatuwana tank (139.4 ± 0.21 ppt) and the lowest was detected in Ridiyagama tank (5.3 ± 0.94). At wet season, 2-MIB levels ranged from 4.4 ± 0.78 to 73.8 ± 0.65 ppt, where the highest level was recorded in Jayanthi tank (73.8 ± 0.65 ppt), while the lowest was detected in Ridiyagama tank (5.3 ± 0.39 ppt). Recorded 2- MIB level was greater in dry season compared to the wet season. Seventy five percent (75%) of the sampling locations exceeded the human threshold levels of 2-MIB (5 ppt). Questionnaire survey showed that more than 95% end water consumers rejected drinking water contaminated with 2-MIB. Further it was found that the total cyanobacterial cell density (T.C.D) was positively correlated with 2-MIB and total phosphorous levels (p<0.05). Moreover, cell densities of Oscillatoria, Anabaena and Cylindrospermopsis species showed significant positive correlations (p<0.05) with 2-MIB contamination levels along with Pearson Correlation Coefficients (P.C.C) of 0.788, 0.682 and 0.731. However, no significant correlation was observed between Microcystis sp. and 2-MIB. Further, 2-MIB showed significant positive correlation (p<0.05) with total phosphorous (P.C.C 0.876), electrical conductivity (EC) (P.C.C, 0.771), and pH (P.C.C, 0.825). Increment of pH value leading to alkalinity is a known optimum condition for cyanobacteria growth while the current study shows alkalinity is favorable for 2-MIB. No significant correlation was obtained between total nitrogen (Nitrate –N, Nitrite –N, Ammonia –N) and 2-MIB nor T.C.D and total nitrogen. Thus, the results of the study indicate there is a direct positive correlation between 2-MIB, cyanobacteria and total phosphorous.
  • No Thumbnail Available
    Item
    Relationships between water quality parameters and geosmin contamination in water bodies in North Central and Eastern Provinces in Sri Lanka.
    (International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Ganegoda, S.; Chinthaka, S.D.M.; Manage, P.M.
    Geosmin (a tertiary alcohol) is a secondary metabolite of aquatic cyanobacteria and actinomycetes. Geosmin contamination produces earthy taste and odour in drinking water. Geosmin cannot be removed by heating the water at 100ºC. Human sensory threshold range of geosmin is 5 to 40 ngL-1, therefore trace levels in the drinking water leads to consumer rejection. In this study, water samples collected from 12 water bodies in North Central (Anuradhapura, Pollonnaruwa) and Eastern provinces (Ampara, Batticcaloa and Trincomalee) in Sri Lanka were analyzed for geosmin content using gas chromatography–mass spectrometry coupled with solid-phase micro extraction. Water pH, temperature, dissolved oxygen (DO) and electrical conductivity (EC) were measured on site and nitrate-N, nitrite-N, ammonia-N, total phosphorous, hardness and total cell density of cyanobacteria were measured off site using standard methods. Water quality was evaluated with an empirical approach using Principal Component Analysis (PCA) which identified three different clusters based on geosmin content, total odour and taste forming cyanobacteria cell density and physico-chemical parameters. Nuwara wewa, Tissa wewa and Nachchadoowa wewa were clustered together with high geosmin, pH, EC, total phosphorous and total odour and taste forming cyanobacteria whereas Unnichchi tank, Kondawatuwana tank and Kanthale tank were clustered together with nitrate–N and DO values. The third cluster consisted of Jayanthi wewa and Sagama tank with nitrite – N values. The highest geosmin level was recorded in Nuwara tank (10.9 ngL-1) and the lowest was detected in Nallachchiya tank (7.8 ngL-1). Geosmin levels in the water from Jayanthi tank, Sagama tank, Kondavatuwana tank, Unnichchi tank and Kantale tank were below the detection limit (<1.5 ngL-1). Water pH, EC, hardness, total phosphorous, N-Nitrate and N-ammonia levels were within the SLSI drinking water standard range. Tissa wewa had a high N-nitrite content (16.54 mgL-1) exceeding SLSI drinking water standards (3 mgL-1). All other water bodies had a safe N-nitrite range for drinking purpose. A significant positive correlation (p<0.05) between total phosphorus and geosmin content was found indicating total phosphorus may be the limiting factor for the production/existence of geosmin. In addition, geosmin content was positively correlated (p<0.05) with EC and pH indicating high dissolved ions and high alkalinity might support geosmin content in water. Geosmin and total odour and taste forming cyanobacteria cell density were correlated positively (p<0.05) showing their positive association. The results revealed that it is necessary to use modern treatment facilities in the drinking water treatment plants in order to remove geosmin contamination prior to distribution of drinking water for general public.