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Item Biological remedies towards safe water...(Proceedings of the Twenty Fourth Scientific Sessions of the Sri Lanka Association for Fisheries and Aquatic Resources, 2018) Wijeyaratne, W.M.D.N.Water is considered as the most essential component in the human livelihood. Rapidly increasing world population, mainly in the developing countries in parts of Asia, North Africa and the Middle East, and sub-Saharan Africa have placed an inordinate demand on safe drinking and potable water. This ever increasing water demand have exceeded the avaiiabie suppiy oi safe fresh water in many regions oi the world. Some major river basins in Asia, North Africa and Middle East are facing severe water scarcity, and over extraction of ground water resources has become a growing problem in many parts of the world. The water scarcity problems are further intensified by increased water pollution due to point and non-point source inputs from urban, industrial and agricultural sectors. Water pollution has imposed severe health issues on human populations and ecological health impairments in aquatic ecosystems. Ensuring universal access to affordable and safe drinking water by 2030 is a target in one of the sustainable development goals. Therefore, the national and international efforts are being initiated to improve water purification infrastructure, provide proper •sanitation facilities, and encourage hygiene in rural, urban and sub urban communities. In addition, the importance of protection and restoration of water- related ecosystems such as forests, mountains, wetlands and riversäs identified in- order to mitigate water scarcity. However, the costs of treating polluted water and restoring water bodies has become a major concern in many countries. The cost of water treatment and aquatic ecosystem restoration requires investment of large amounts of funds and labor, which is unbearable by most of the developing and technology lagging countries. Therefore, natural and synthetic remediation methods have been studied to improve the quality of the contaminated water in many parts of the world, Compared to the chemical purification methods, use of natural materials is increasingly popular among many research groups as these methods provide more cost-effective, environmentally friendly alternatives of water purification. Biological water purification methodologies can be in treatment of domestic drinking water as well as for treating waste water before releasing thém to the environment. Many traditional water purification methodologies that have in practice for decades have been improved and modified by recent research findings to cater for wider community in need of purified water. Further, Many research have been to identify effective plant and microbial aggregations that can serve as universal communities in constructed wetlands in terms of remediation of heavy metal, suspended solids and nutrient pollution. treatment increasing'} researched 2nd as they can destroy and remove multiple contaminants simultaneously and have minimum sludge production and bacterial regrowth. Biological treatment can be used to remove natural organic matter, cclour, chloroform, perchlorate, nitrate, nitrite, bromate, iron, manganese, chromate, arsenate, and a variety of other contaminants cf polluted y.'2ter . cy.id2ticn prier to filtraticn cr settling, as wetl as the need for chemical reduction methods, and produces innocuous end-products, thus reducing the risk Of a contaminating the natural aquatic systems. Therefore, to achieve the sustainable development goal of ensuring availability and sustainable management of water and sanitation for all by 2030, the importance of the role of living organisms in water purification needs to be given a top priority as life and water is the driving force towards a sustainable future.Item Application of Allium cepa bioassay to study the spatial variation of potential cytotoxicity in relation to water quality in the Dandugan Oya, Sri Lanka(Research Symposium on Pure and Applied Sciences, 2018 Faculty of Science, University of Kelaniya, Sri Lanka, 2018) Wadasinghe, L. G. Y. J. G.; Wijeyaratne, W. M. D. N.Water quality is an important indicator in measuring the health of aquatic ecosystems. Poor water quality can lead to ecological health impairment. Dandugan Oya is receiving industrial waste from multiple sources. In addition, the raw water for the public water supply in some suburban areas in the Gampaha District is obtained from the Dandugan oya. In this study, potential cytotoxic effects of the water in selected sites of the Dandugan Oya were assessed using Allium cepa bioassay. Surface water samples were collected from six sites (Site A: Urban site; B and D: Industrial sites; C: public water supply intake; E: Agricultural site; F: Reference site with pristine environmental conditions) at two month intervals from May to November 2017. Water samples were collected from each site (n=10) and temperature, pH, conductivity, biochemical oxygen demand (BOD), dissolved oxygen concentration (DO), total dissolved solids (TDS) and chemical oxygen demand (COD) were analysed using standard analytical methods. Potential cytotoxicity of these water samples were assessed using Allium cepa bioassay. Spatial variation of water quality and cytotoxic end points were analysed by ANOVA followed by Tukey’s pairwise comparison using MINITAB 14 software. Significantly lower DO was recorded from sites C (4.0 ± 0.3 mg/L) and D (4.3 ± 0.4 mg/L) and significantly high COD was recorded from site D (267.1 ± 56.5 mg/L) (p<0.05). Significantly high TDS and conductivity were recorded from sites A and B (p<0.05). Mean nuclear abnormalities of the root tip cells of the A . cepa bulbs exposed to the surface water samples collected from the study sites ranged from 9‰ to 83‰ where significantly higher (p<0.05) nuclear abnormalities were recorded from site C (83 ± 2.4‰). Occurrence of nuclear buds and condensed nuclei in the interphase cells of the A . cepa root tips exposed to water samples from the site C (18 ± 0.8‰ and 61 ± 2.0‰) were significantly higher compared to the reference site (2 ± 0.1‰ and 4 ± 0.1‰)(p<0.05). Further, Site D also showed significantly high (p<0.05) nuclear bud formation (15 ± 0.4‰) and highest binuclei formation (6‰ ± 0.2) compared to the reference site. The results of the present study indicated occurrence of potentially high cytotoxicity in the A . cepa bioassay in the water at site C, which is the water intake site of Dandugan Oya for public water supply. Therefore, further investigations on the identification of the active forms of cytotoxic contaminants and continuous monitoring of water quality in these sites of Dandugan Oya is important in order to maintain the ecosystem and human health.