Programme INTERREG III : STARDUST Spatial and Temporal Assessment of high Resolution Depth profiles Using novel Sampling Technologies                                                              Vlaams Institute voor de Zee Université des Sciences et Technologies de Lille Vrije Universiteit Brussel Study of organic contaminants in river sediments Adeline CHARRIAU, Laurent BODINEAU, Baghdad OUDDANE 27-6-2019 Herhaling titel van presentatie Lille, march 28th 2008

Context of the study  Compounds of interest: hydrophobic contaminants Cl x Polychlorobiphenyles (PCB) - proven toxicity - persistence in the aquatic ecosystems - bioaccumulative character Polycyclic Aromatic Hydrocarbons (PAH) n-alkanes Contamination levels and potential toxicity Source apportionment (biologic, petrogenic, pyrolytic)  River sediments: acted as a sink for contaminants but can represent a threat in case of a release to the overlying water column 1

Optimisation of analytical tools and procedures  Optimisation of extraction conditions for aliphatic and aromatic hydrocarbons Analysis of polychlorobiphenyls by mass spectrometry - good preliminary results in the SIS mode - validation of the analytical procedure in progress for the Tandem mode Time saving Higher reproducibility Higher sensitivity for planar PCB 2

Organic contaminants in river sediments [1] Sampling area Yser canal Superficial sediments  Lys canal Escaut canal Espierre canal Superficial sediments and sediment cores 3

Organic contaminants in river sediments [2] Yser canal n-alkanes - Total concentrations range: 2.9 – 16.2 mg/kg - Absence of unresolved complex mixture - Major hydrocarbons coming from biogenic sources (higher plant waxes) - High amounts of low molecular weight n­alkanes for sediments 1 to 6 PAH - Total concentrations range: 0.5 – 4.2 mg/kg Predominance of high molecular weight PAH Strong pyrolitic fingerprint Lower concentrations in the upstream part of the river 4

Organic contaminants in river sediments [3] Prospecting campaign Espierre I.1 Espierre I.2 Helkijn II.1 Helkijn II.2 Helkijn II.3 Helkijn II.4 Bleharies III.1 Wervik IV.1 Wervik IV.2 Wervik IV.3 PAH n-Alkanes n-alkanes - Total concentrations range: 6.4 – 55.7 mg/kg High and homogeneous contamination for Wervik sediments Lower concentrations in the Escaut canal Scheldt PAH - Total concentrations range: 1.5 – 33.9 mg/kg - Higher heterogeneity Lower concentrations in the confluence with the Scheldt canal Evaluation of accessibility, presence of muddy sediments and contamination levels 5

Organic contaminants in sediment cores [1] Molecular fingerprint Petroleum Petroleum combustion Biomass and coal combustion Combustion Mixed Bordery lines based on Yunker et al., 2002 PAH molecular indices consistent with combustion process presence of alkyl homologues Major pyrolitic origin and minor part from petrogenic process n-alkanes presence of a broad and large UCM major n-alkanes of biogenic origins (C27, C29, C31) UCM 28 27 29 30 31 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 32 33 34 Phy Pri Terrestrial inputs and biodegraded oil residues 6

Organic contaminants in sediment cores [2] Risk assessment ERL Sediment Quality Guidelines - ERL value exceeded for Helkijn and Wervik sediments - ERM value exceeded for Espierre sediments ERM Global threshold value of the European legislation (8.649 mg.kg –1) - exceeded for all Espierre sediments (more than 6 times the recommended value) - exceeded for surface and bottom sediments of Wervik 7

Conclusions High contamination levels for Helkijn, Wervik and especially Espierre sediments: potential threat for the aquatic ecosystems Strong historical contamination in the Espierre canal (PAH and degraded oil residues) Strong pyrolytic inputs for PAH  Trans-boarder benefits: joint samplings and comparison with Calux results 8