ORCID Profile
0000-0002-2961-9064
Current Organisation
University of Kelaniya
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Publisher: Elsevier BV
Date: 03-2021
Publisher: Springer Science and Business Media LLC
Date: 03-08-2020
Publisher: IWA Publishing
Date: 26-08-2021
DOI: 10.2166/WST.2021.339
Abstract: Bioavailable content of metals in aquatic systems has become critical in assessing the toxic effect of metals accumulating in the environment. Considering the need for rapid measurements, an optical microalgal-cyanobacterial array biosensor was developed using two strains of microalgae, Mesotaenium sp. and a strain of cyanobacteria Synechococcus sp. to detect Cd2+, Cr6+ and Zn2+ in aquatic systems. Microalgal and cyanobacterial cells were immobilized in a 96-well microplate using sol-gel method using silica. Optimum operational conditions for the biosensor array such as exposure time, storage stability, pH, and multiple metal effect were tested. A 10 min exposure time yielded optimum fluorescence values. Metal toxicity increased with decreasing pH, resulting in low relative fluorescence (%) and decreased with increasing pH, resulting in higher relative fluorescence (%). The optimum storage time for biosensor strains were 4 weeks for microalgal cultures and 8 weeks for cyanobacterial culture, at 4 °C storage temperature. The metal mixtures showed less effect on the inhibition of relative fluorescence (%) of microalgal/cyanobacterial cultures, displaying an antagonistic behavior among the metals tested. As a single unit, this photosynthetic array biosensor will be a valuable tool in detecting multi-metals in aquatic systems.
Publisher: Springer Science and Business Media LLC
Date: 21-04-2016
DOI: 10.1007/S00128-016-1809-4
Abstract: Sensitivity of four tropical cyanobacteria viz. Coelosphaerium sp., Synechococcus sp., Oscillatoria sp. and Chroococcus sp. to environmentally relevant concentrations of Cr(6+), Cd(2+) and Zn(2+)was assessed based on fluorescence change as a proxy for growth reduction. At 24 h exposure, the growth reduction inthe cyanobacteria followed the order: Zn(2+) < Cr(6+) ≤ Cd(2+). Of the four cyanobacteria, Synechococcus was the most sensitive for Cr(6+), where as Chroococcus was the most sensitive for Cd(2+)and Zn(2+). Sensitivity was gradually decreased by 96 h implying the acquisition of tolerance by cyanobacteria to heavy metal ions with prolonged exposure.
Publisher: Wiley
Date: 22-12-2016
DOI: 10.1002/ETC.3199
Abstract: To assess the potential impacts of agricultural pesticides on tropical freshwater ecosystems, the present study developed temperature-specific, freshwater species protection concentrations (i.e., ecotoxicity threshold values) for 8 pesticides commonly detected in Australia's tropical freshwaters. Because relevant toxicity data for native tropical freshwater species to assess the ecological risks were mostly absent, scientifically robust toxicity data obtained at ≥20 °C were used for ecologically relevant taxonomic groups representing primary producers and consumers. Species sensitivity distribution (SSD) curves were subsequently generated for predicted chronic exposure using Burrlioz 2.0 software with mixed chronic and converted acute data relevant to exposure conditions at ≥20 °C. Ecotoxicity threshold values for tropical freshwater ecosystem protection were generated for ametryn, atrazine, diuron, metolachlor, and imidacloprid (all moderate reliability), as well as simazine, hexazinone, and tebuthiuron (all low reliability). Using these SSD curves, the retrospective risk assessments for recently reported pesticide concentrations highlight that the herbicides ametryn, atrazine, and diuron are of major concern for ecological health in Australia's tropical freshwater ecosystems. The insecticide imidacloprid also appears to pose an emerging threat to the most sensitive species in tropical freshwater ecosystems. The exposed temperature-specific approach may be applied to develop water quality guideline values for other environmental contaminants detected in tropical freshwater ecosystems until reliable and relevant toxicity data are generated using representative native species.
No related grants have been discovered for Asoka Pathiratne.