...Daphnia Introduction: Daphnia is a large genus comprising over 200 species of small freshwater crustaceans that belongs to the family Daphniidae and the order “Cladocera”. The common name of Daphnia is water flea and this name is due to jerky-flea like swimming movement. Daphnia often live is freshwater bodies of relative different quality including swamps, lakes, streams and rivers. Description: Daphnia in general are small and may range from as small as 0.5 mm to as long as 5.0 mm in length, sometimes more; and hence some daphnia species can be seen by naked eyes (e.g. Daphnia magna) , while others must are microscopic (e.g. Daphnia pulex). Usually females are larger than males and have a brood chamber under their carapace where eggs are kept. The uncalcified...
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...focusses on recent advances in dispersant effectiveness, toxicity, and biodegradation. Other topics such as application, use, behaviour and fate are also covered. The prime motivation for using dispersants is to reduce the impact of oil on shorelines, thus the application must be successful and effectiveness high. As some oil would come ashore, discussion remains on what effectiveness is required to significantly reduce the shoreline impact. A major issue is the actual effectiveness during spills so that these values can be used in estimates for the future. The second motivation for using dispersants is to reduce the impact on birds and mammals on the water surface. The benefits of using dispersants to reduce impacts on wildlife still remain unknown. The third motivation for using dispersants is to promote the biodegradation of oil in the water column. The effect of dispersants on biodegradation is still a matter of dispute. Some papers state that dispersants inhibit biodegradation others indicate that dispersants have little effect on biodegradation. The most recent papers, however, confirm that inhibition is a matter of the surfactant in the dispersant itself and the factors of environmental conditions. It is clear, on the basis of current literature that the surfactants in some of the current dispersant formulations can inhibit biodegradation. No...
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