title: Remediation of contaminated marine sediment using thin-layer capping with activated carbon--a field experiment in Trondheim harbor, Norway.
abstract: In situ amendment of contaminated sediments using activated carbon (AC) is a recent remediation technique, where the strong sorption of contaminants to added AC reduces their release from sediments and uptake into organisms. The current study describes a marine underwater field pilot study in Trondheim harbor, Norway, in which powdered AC alone or in combination with sand or clay was tested as a thin-layer capping material for polycyclic aromatic hydrocarbon (PAH)-contaminated sediment. Several novel elements were included, such as measuring PAH fluxes, no active mixing of AC into the sediment, and the testing of new manners of placing a thin AC cap on sediment, such as AC+clay and AC+sand combinations. Innovative chemical and biological monitoring methods were deployed to test capping effectiveness. In situ sediment-to-water PAH fluxes were measured using recently developed benthic flux chambers. Compared to the reference field, AC capping reduced fluxes by a factor of 2-10. Pore water PAH concentration profiles were measured in situ using a new passive sampler technique, and yielded a reduction factor of 2-3 compared to the reference field. The benthic macrofauna composition and biodiversity were affected by the AC amendments, AC + clay having a lower impact on the benthic taxa than AC-only or AC + sand. In addition, AC + clay gave the highest AC recoveries (60% vs 30% for AC-only and AC + sand) and strongest reductions in sediment-to-water PAH fluxes and porewater concentrations. Thus, application of an AC-clay mixture is recommended as the optimal choice of the currently tested thin-layer capping methods for PAHs, and more research on optimizing its implementation is needed.
authors.affiliation: Norwegian Geotechnical Institute (NGI), P.O. Box 3930 Ullevål Stadium, N-0806 Oslo, Norway. gerard.cornelissen@ngi.no
authors.forename: Gerard
authors.initials: G
authors.lastname: Cornelissen
authors.forename: Marie Elmquist
authors.initials: ME
authors.lastname: Kruså
authors.forename: Gijs D
authors.initials: GD
authors.lastname: Breedveld
authors.forename: Espen
authors.initials: E
authors.lastname: Eek
authors.forename: Amy M P
authors.initials: AM
authors.lastname: Oen
authors.forename: Hans Peter H
authors.initials: HP
authors.lastname: Arp
authors.forename: Caroline
authors.initials: C
authors.lastname: Raymond
authors.forename: Göran
authors.initials: G
authors.lastname: Samuelsson
authors.forename: Jenny E
authors.initials: JE
authors.lastname: Hedman
authors.forename: Øystein
authors.initials: Ø
authors.lastname: Stokland
authors.forename: Jonas S
authors.initials: JS
authors.lastname: Gunnarsson
mesh_terms: D000327:Adsorption; D000704:Analysis of Variance; D000818:Animals; D044822:Biodiversity; D002606:Charcoal / Q000737:chemistry*; D004785:Environmental Pollutants / Q000032:analysis*; D052918:Environmental Restoration and Remediation / Q000379:methods*; D019015:Geologic Sediments / Q000032:analysis*; D007448:Invertebrates; D009664:Norway; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis*; D014741:Video Recording
chemical_list: D004785:Environmental Pollutants; D011084:Polycyclic Aromatic Hydrocarbons; D002606:Charcoal