Study On The Long-term-toxicity Of12Pesticides On Platymonas Subcordiformis And Skeletonema Costatum

The research of pesticide toxicity to ocean single-celled algae is less, In order to protect the marinebiological resources, gain basic data of evaluation on the marine environment and find out some sensitivealgae or index as a marine environmental evaluation index, in the thesis，Platymonas subcordiformis andskeletonema costatum have been choosen as the experiment objects, ultraviolet spectrophotometry wasused to test the Long-term toxicity of12kinds of common pesticides on the two ocean single-celledalgae。The results are as follows:（1）The Long-term toxicity of12kinds of common pesticides on Platymonas subcordiformis andSkeletonema costatum fits the following rules basically：Firstly，it has an obvious time effect-theInhibition rate Straights up until it gets to the highest point and then it drops. Secondly, it has an obviousConcentration effect-high concentrations of pesticides has toxic effect, while low concentrations ofpesticides may promote the growth of algae.（2）There are differences between the long-term toxicity of different pesticides on the same algae. Tothe same algae, the chemical structure, mechanism of action of pesticides will affect the long-termtoxicity of the pesticide. Furthermore, different algae have different effects to the same pesticide. Theorder of long-term toxicity of three kinds of pesticides on2experiment algae is as follows: herbicide＞fungicide＞insecticide.（3）The maximum inhibitory effect of pesticides on algae will change with the variation of pesticide,concentration and algae. The maximal inhibition rate of prometryn to Platymonas subcordiformisoccursoccurs on the third day, while it to Skeletonema costatum, the maximal inhibition rate occurs on the4thday. when the concentration is more than1mg L^-1, The maximal inhibition rate of triadimefon onskeletonema costatum occours on the3rd day.while the concentration is not more than1mg L^-1, itoccours on the2nd day. The maximal inhibition rate of parathion on platymonas subcordiformis occourson the3rd day, while the maximal inhibition rate of parathion on skeletonema costatum occours on the5th day.（4）Pesticide with low concentration may accelerate the growth of the two ocean algae. In this test,only Bialaphos and triadimefon could not act on Platymonas subcordiformis; when the concentration ofmetalaxyl is between10mg L^-1and20mg L^-1, on the8th day， growth-stimulating occurs in the both twoalgaes. When the concentration of metolcarb is less than0.2mg L^-1, the enhanceing rate to Skeletonema costatum rises to max:60%.but when growth-promoting effect occurs, the time and oncentration ofpestcides are different with diferent algas or different pestcides. On the7th day, when the concentrationof glyphosate is2mg L^-1, the growth-promoting effect occurs in skeletonema costatum, but whenglyphosate is changed by bialaphos, it does not occur. when the concentration of metalaxyl are10mg L^-1and20mg L^-1, the growth-promoting effect occurs in Platymonas subcordiformis on the8th day. Whenthe concentration are max than20mg L^-1or min than10mg L^-1, it does not occur.（5）with the effect of low concentration of carbamate pesticides, The inhibition rate to platymonassubcordiformis descended during the whole test..