A Time-Dose Response Model to Assess Diuron-Induced Photosynthesis Inhibition in Freshwater Biofilms
Morin, S. ; Chaumet, B. ; Mazzella, N.
Type de document
Article de revue scientifique à comité de lecture
Affiliation de l'auteur
IRSTEA BORDEAUX UR EABX FRA ; IRSTEA BORDEAUX UR EABX FRA ; IRSTEA BORDEAUX UR EABX FRA
Résumé / Abstract
Contamination by herbicides is reported in most freshwater environments. These biologically active compounds may impact the non-target biota such as benthic bioﬁlms, at the base of the trophic chain. In agricultural watersheds, herbicides occur as pulses in the system, and traditional dose-response analysis performed at a given duration of exposure (hours to days) may not predict accurately the risk of adverse impacts at shorter temporal scales (minutes to hours) corresponding to pulse exposures. To assess the time-response relationship in bioﬁlms exposed to herbicides, we used diuron, an inhibitor of photosynthesis, to perform bioassays (time-response curves) with the aim of characterizing the initial steps of photosynthesis decrease after exposure to the herbicide (from seconds to hours), for different concentrations of exposure. Diuron-induced inhibition of photosynthesis reﬂects blockage of electron transfer in PSII, therefore we deﬁned the time lag to reach the threshold of 50% photosynthesis inhibition (t1/2) as the time for diuron to reach its target site (adsorption, distribution). We found a rapid decrease in photosynthetic efﬁciency: t1/2 values were dose-dependent and ranged from
Frontiers in Environmental Science, vol. 6, num. 131, 9 p.