Le jeudi 20 mars 2014 à 11h00, en salle de conférences de l'OSUR, campus de Beaulieu, bât.
Le jeudi 20 mars 2014 à 11h00
, en salle de conférences de l'OSUR, campus de Beaulieu, bât. 14b, UR1Environmental variables influencing denitrification rates in aquatic sedimentsRésumé :
The ecological functioning of the Seine estuary is strongly affected by the input of nitrogen, especially in the form of nitrate. Modeling studies have shown that up to 40% of the nitrogen can be eliminated in riparian zones and between 15 à 20 % in the water column, most likely due to denitrification. The work presented aimed to improve the understanding of nitrogen fluxes at the sediment water interface, more specifically factors influencing denitrification. Two key factors - nitrate and carbon - were investigated. The effect of these variables was determined using “flow-through reactors”, allowing rate determination under controlled conditions, using intact sediment and thus the resident microbial community and site specific sediment conditions. In addition to nitrate rate measurements, the use of 15N-NO3- analyses allowed the determination of the 15N-NO3- enrichment factors (e) of the benthic denitrifying communities.
Denitrification rates in the Seine River sediments are found to be strongly nitrate and carbon limited. Optimizing environmental conditions to increase benthic denitrification rates in order to mitigate nitrogen pollution are thus feasible. Effects of possible inhibitors (antibiotics) on denitrification rates in aquatic sediments will also be discussed.Contact : Anniet LAVERMAN