Article (Scientific journals)
Factors controlling spatial and temporal patterns of multiple pesticide compounds in groundwater (Hesbaye chalk aquifer, Belgium)
Hakoun, Vivien; Orban, Philippe; Dassargues, Alain et al.
2017In Environmental Pollution
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Abstract :
[en] Factors governing spatial and temporal patterns of pesticide compounds (pesticides and metabolites) concentrations in chalk aquifers remain unclear due to complex flow processes and multiple sources. To uncover which factors govern pesticide compound concentrations in a chalk aquifer, we develop a methodology based on time series analyses, uni- and multivariate statistics accounting for concentrations below detection limits. The methodology is applied to long records (1996–2013) of a restricted compound (bentazone), three banned compounds (atrazine, diuron and simazine) and two metabolites (deethylatrazine (DEA) and 2,6–dichlorobenzamide (BAM)) sampled in the Hesbaye chalk aquifer in Belgium. In the confined area, all compounds had non-detects fractions >80%. By contrast, maximum concentrations exceeded EU’s drinking-water standard (100 ngL-1) in the unconfined area. This contrast confirms that recent recharge and polluted water did not reach the confined area, yet. Multivariate analyses based on variables representative of the hydrogeological setting revealed higher diuron and simazine concentrations in the southeast of the unconfined area, where urban activities dominate land use and where the aquifer lacks protection from a less permeable layer of hardened chalk. At individual sites, positive correlations (up to τ =0,48 for bentazone) between pesticide compound concentrations and multi-annual groundwater level fluctuations confirm occurrences of remobilization. A downward temporal trend of atrazine concentrations likely reflects decreasing use of this compound over the last 28 years. However, the lack of a break in concentrations time series and maximum concentrations of atrazine, simazine, DEA and BAM exceeding EU’s standard post-ban years provide evidence of persistence. Contrasting upward trends in bentazone concentrations show that a time lag is required for restriction measures to be efficient. These results shed light on factors governing pesticide compound concentrations in chalk aquifers. The developed methodology is not restricted to chalk aquifers, it could be transposed to study other pollutants with concentrations below detection limits. Several factors govern pesticide compounds concentrations in the chalk: hydrogeological setting, land use, groundwater level fluctuations and persistence.
Research center :
UEE - Urban and Environmental Engineering - ULiège
Disciplines :
Earth sciences & physical geography
Geological, petroleum & mining engineering
Author, co-author :
Hakoun, Vivien;  Université de Liège > Département ArGEnCo > Hydrogéologie & Géologie de l'environnement
Orban, Philippe  ;  Université de Liège > Département ArGEnCo > Hydrogéologie & Géologie de l'environnement
Dassargues, Alain  ;  Université de Liège > Département ArGEnCo > Hydrogéologie & Géologie de l'environnement
Brouyère, Serge  ;  Université de Liège > Département ArGEnCo > Hydrogéologie & Géologie de l'environnement
Language :
English
Title :
Factors controlling spatial and temporal patterns of multiple pesticide compounds in groundwater (Hesbaye chalk aquifer, Belgium)
Publication date :
2017
Journal title :
Environmental Pollution
ISSN :
0269-7491
eISSN :
1873-6424
Publisher :
Elsevier Science, Oxford, United Kingdom
Peer reviewed :
Peer Reviewed verified by ORBi
European Projects :
FP7 - 265063 - ADVOCATE - Advancing Sustainable In Situ Remediation for Contaminated Land and Groundwater
Funders :
DG RDT - Commission Européenne. Direction Générale de la Recherche et de l'Innovation [BE]
CE - Commission Européenne [BE]
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since 22 January 2017

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