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
Langue
Anglais
Affiliation de l'auteur
IRSTEA BORDEAUX UR EABX FRA ; IRSTEA BORDEAUX UR EABX FRA ; IRSTEA BORDEAUX UR EABX FRA
Année
2018
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
Source
Frontiers in Environmental Science, vol. 6, num. 131, 9 p.

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