بررسي و مقايسه تاثيرات دو صدف DREISSENA POLYMORPHA و ANODONTA CYGNEA بر كاهش غلظت نيترات

The Comparison Affection of Dreissena polymorpha and Anodonta cygnea in Concentration of Nitrate

Dreissena polymorpha and Anodonta cygnea of Bivalvia class are able to filter organic and inorganic materials through the water. Nowadays the filtrations rates of these organisms are studied as a tool for treatment and removing suspended and dissolved materials. So in this research, the affection of these two mussels on nitrate concentration is studied that indirectly reduces concentration of nitrate due to filtration tests and indirect absorption of nitrate from artificial wastewater. These tests were performed by method J0rgensen (1990) in open and closed systems. This research is done in 3 different weights of mussels and was repeated 3-10 times in Science & Research University laboratory in 2006. Its result was studied in excel soft ware. In two species in open and closed systems the result showed that there is a positive correlation between the weight of shell masses and the filtration rate of nitrate and the filtration rate of Chlorella (R2=0.99). In D. polymorpha there is a negative correlation between concentration of nitrate at the wastewater entry on one side and the filtration rate of nitrate on the other side (R2=0.97) despite the fact that in A. cygnea there is a positive correlation between concentration of nitrate at the wastewater entry and the filtration rate of nitrate (R2=0.90). The result also showed that the absorption rate of nitrate in D. polymorpha is 0.001 - 0.004 mg.l1 and in A. cygnea is 0.003-1.4 mg.l1.