title: Bioassay responses and effects on benthos after pilot remediations in the delta of the rivers Rhine and Meuse.
abstract: Chemical and biological monitoring was carried out for 5 years following pilot remediations at two locations in the Rhine-Meuse delta. The remediations consisted of partial excavation of the contaminated sediments, followed by applying a clean layer of sandy material on top. After the remediation, a new silty sediment top layer was formed exhibiting a lower toxicity in five sediment/sediment pore water bioassays. Compared to the unremediated sites, lower metal and PAH concentrations were found at the remediated sites, but in one location at the same time elevated HCH, PCB and HCB levels were recorded. One year after the remediation, the differences became smaller, although effects-based classification showed that the remediated site showed a higher quality up to the last year. In both remediated sites a rapid recolonization of nematodes, oligochaetes and chironomids was observed, while the recolonization by bivalves was slower. A few years after the remediation the differences decrease.
authors.affiliation: Institute for Inland Water Management and Waste Water Treatment (RIZA), Ministry of Transport, Public Works and Water Management, PO Box 17, 8200 AA Lelystad, The Netherlands. p.dbesten@riza.rws.minvenw.nl
authors.forename: Pieter J
authors.initials: PJ
authors.lastname: den Besten
authors.forename: Paul J
authors.initials: PJ
authors.lastname: van den Brink
mesh_terms: D000818:Animals; D001673:Biodegradation, Environmental; D001681:Biological Assay; D049872:Bivalvia / Q000502:physiology*; D004784:Environmental Monitoring / Q000379:methods*; D019015:Geologic Sediments / Q000032:analysis*; D007448:Invertebrates / Q000502:physiology*; D019216:Metals, Heavy / Q000032:analysis; D009426:Netherlands; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis; D045483:Rivers; D013997:Time Factors; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D019216:Metals, Heavy; D011084:Polycyclic Aromatic Hydrocarbons; D014874:Water Pollutants, Chemical