ROLE OF TEMPERATURE ON ISOPROTURON BIOACCUMULATION AND EFFECTS ON 2 FRESH-WATER ROOTED MACROPHYTES - ELODEA-DENSA AND LUDWIGIA-NATANS

The effects of temperature on the bioaccumulation of the phenylurea he rbicide isoproturon (IPU) and on the growth inhibition induced on two freshwater rooted macrophytes-Elodea densa and Ludwigia natans-were in vestigated using indoor microcosms, The experimental protocol was base d on five temperatures (12, 16, 20, 24, and 28 degrees C) and two cont amination levels of the water column (30 and 60 mu g IPU.liter(-1)), p lus a control condition, Variations in temperature had little effect o n the decrease in [IPU] in the water column during the 21-day experime nt, The IPU concentration in the two macrophyte species was not signif icantly modified by the large range of temperatures when results were expressed using the concentration criterion. IPU burdens in the E. den sa cuttings, on the other hand, increased significantly when the tempe rature rose from 12 to 28 degrees C; small differences were observed b etween the two exposure conditions, in relation to the antagonistic ef fects of IPU and temperature on the growth of the cuttings, Bioconcent ration factors in the plants (stems + leaves) were close to 10 and 13 after exposure to 30 and 60 mu g IPU.liter(-1), respectively. (C) 1997 Academic Press.