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Submitted on 16 May 2020
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Assessing diuron short-term effects on biofilms using time-response curves
Soizic Morin, B. Chaumet, Nicolas Mazzella
To cite this version:
Soizic Morin, B. Chaumet, Nicolas Mazzella. Assessing diuron short-term effects on biofilms using time-response curves. Ecotoxicomic 2017 - First International Conference on Microbial Ecotoxicology, Nov 2017, Lyon, France. pp.1, 2017. �hal-02606871�
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More about diuron bioaccumulation on:
Wed, 10:40
Transfer and distribution of diuron in biofilms
and joint toxic effects
by Betty Chaumet
Assessing diuron short-term effects on biofilms
using time-response curves
Soizic Morin, Betty Chaumet, Nicolas Mazzella
Irstea, UR EABX, 50 avenue de Verdun, 33612 Cestas cedex France
In agricultural watersheds, stream pollutions by ORGANIC PESTICIDES occur as short-time events.
In the case of rapidly-acting compounds such as the herbicide DIURON, pulse exposure may lead to dramatic impacts on biofilm microalgae. Assessing the effects of diuron over short periods of time is therefore necessary.
Here we assess the DOSE, TIME and DOSE-TIME RESPONSE of freshwater BIOFILMS to diuron, using photosynthesis inhibition as an endpoint.
But EC50 is dependent on exposure duration
Diuron reaches
its cellular target in a very short time-span
The delay (t1/2) to halve photosynthesis
depends on test [diuron]
Diuron binding is
faster than its release
Toxicity tests
DOSE
-
RESPONSE CURVESΦPSII = f([diuron]),
exposure duration = fixed
TIME
-
RESPONSE CURVESΦPSII = f(exp. duration),
[diuron] = fixed
diuron
Methods
MICROALGAL BIOFILMS
4-wk old, on glass slides
DIURON–induced inhibition of photosynthetic
efficiency (ΦPSII)
TEST EXPOSURE ~ EC100
0 0.1 0.2 0.3 0.4 0.5 0.6
0:00 0:28 0:57 1:26
t1/2 = 0’16’’ - 7’20’’
ΦPSII
0 0.1 0.2 0.3 0.4 0.5 0.6
0:00 0:02 0:05 0:08 0:11 0:14
t1/2 = 0’16’’
ΦPSII
Confirmed for
different biofilms
TEST EXPOSURE: [DIURON] = EC25 [DIURON] = EC50 [DIURON] = EC100
TEST EXPOSURE = 3HRS
Increasing diuron
concentrations cause photosynthesis inhibition
0 0.1 0.2 0.3 0.4 0.5 0.6
0 1 10 100 1 000 10 000
[diuron], in µg/L
EC25 ~5µg/L
EC50 ~13µg/L
EC100 >100µg/L
ΦPSII
R²=0.997, p<0.001
1 10 100 1000
0.1 1 10 100
Time post contamination (minutes) EC 50 diuron (µg.L-1 )
15 seconds 30 seconds 1 minute 2 minutes 5 minutes 10 minutes 20 minutes 3 hours (DRC)
Time post diuron addition/removal
0 20 40 60 80 100
0:00 2:24 4:48 7:12 9:36
decrease post exposure increase post removal
% of optimal ΦPSII
