Hamonts, K.* ; Kuhn, T. ; Vos, J.* ; Maesen, M.* ; Kalka, H.* ; Smidt, H.* ; Springael, D.* ; Meckenstock, R.U. ; Dejonghe, W.*
     
 
    
        
Temporal variations in natural attenuation of chlorinated aliphatic hydrocarbons in eutrophic river sediments impacted by a contaminated groundwater plume.
    
    
        
    
    
        
        Water Res. 46, 1873-1888 (2012)
    
    
		
		
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			Open Access Green möglich sobald Postprint bei der ZB eingereicht worden ist.
		
     
    
		
		
			
				Chlorinated aliphatic hydrocarbons (CAHs) often discharge into rivers as contaminated groundwater baseflow. Biotransformation, sorption and dilution of CAHs in the impacted river sediments have been reported to reduce discharge, but the effect of temporal variations in environmental conditions on the occurrence and extent of those processes in river sediments is largely unknown. We monitored the reduction of CAH discharge into the Zenne River during a 21-month period. Despite a relatively stable influx of CAHs from the groundwater, the total reduction in CAH discharge from 120 to 20cm depth in the river sediments, on average 74±21%, showed moderate to large temporal variations, depending on the riverbed location. High organic carbon and anaerobic conditions in the river sediments allowed microbial reductive dechlorination of both chlorinated ethenes and chlorinated ethanes. δ(13)C values of the CAHs showed that this biotransformation was remarkably stable over time, despite fluctuating pore water temperatures. Daughter products of the CAHs, however, were not detected in stoichiometric amounts and suggested the co-occurrence of a physical process reducing the concentrations of CAHs in the riverbed. This process was the main process causing temporal variations in natural attenuation of the CAHs and was most likely dilution by surface water-mixing. However, higher spatial resolution monitoring of flow transients in the riverbed is required to prove dilution contributions due to dynamic surface water-groundwater flow exchanges. δ(13)C values and a site-specific isotope enrichment factor for reductive dechlorination of the main groundwater pollutant vinyl chloride (VC) allowed assessment of changes over time in the extent of both biotransformation and dilution of VC for different scenarios in which those processes either occurred consecutively or simultaneously between 120 and 20cm depth in the riverbed. The extent of reductive dechlorination of VC ranged from 27 to 89% and differed spatially but was remarkably stable over time, whereas the extent of VC reduction by dilution ranged from 6 to 94%, showed large temporal variations, and was often the main process contributing to the reduction of VC discharge into the river.
			
			
				
			
		 
		
			
				
					
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        Publikationstyp
        Artikel: Journalartikel
    
 
    
        Dokumenttyp
        Wissenschaftlicher Artikel
    
 
    
        Typ der Hochschulschrift
        
    
 
    
        Herausgeber
        
    
    
        Schlagwörter
        Chlorinated ethenes; Chlorinated ethanes; Reductive dechlorination; Dilution; Groundwater–surface water interaction; Compound-specific isotope analysis
    
 
    
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        Sprache
        englisch
    
 
    
        Veröffentlichungsjahr
        2012
    
 
    
        Prepublished im Jahr 
        
    
 
    
        HGF-Berichtsjahr
        2012
    
 
    
    
        ISSN (print) / ISBN
        0043-1354
    
 
    
        e-ISSN
        1879-2448
    
 
    
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	    Band: 46,  
	    Heft: 6,  
	    Seiten: 1873-1888 
	    Artikelnummer: ,  
	    Supplement: ,  
	
    
 
  
        
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            Verlag
            Elsevier
        
 
        
            Verlagsort
            Amsterdam [u.a.] ; Jena [u.a.]
        
 
	
        
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        Begutachtungsstatus
        Peer reviewed
    
 
     
    
        POF Topic(s)
        20403 - Sustainable Water Management
    
 
    
        Forschungsfeld(er)
        Environmental Sciences
    
 
    
        PSP-Element(e)
        G-504300-004
    
 
    
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        Erfassungsdatum
        2012-02-28