| 1. |
- Amstaetter, Katja, et al.
(författare)
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Sorption of PAHs and PCBs to activated carbon : Coal versus biomass-based quality
- 2012
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Ingår i: Chemosphere. - : Elsevier BV. - 0045-6535 .- 1879-1298. ; 87:5, s. 573-578
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Tidskriftsartikel (refereegranskat)abstract
- The addition of activated carbon (AC) is an increasingly popular method for pollutant immobilization, and the AC material can be made of biomass or coal/fossil feedstock. The aim of the present study was to investigate whether there are differences between pollutant sorption to biomass and coal-based AC in the presence and absence of sediment. Through N-2 and CO2 adsorption to probe surface area and pore size it was shown that the biomass-based AC had a stronger dominance of narrow pores in the size range 3.5-15 angstrom than the anthracite-based material. In the absence of sediment, sorption isotherms for the probe compounds pyrene and PCB-101 showed stronger sorption for the biomass-based AC (logarithmic Freundlich coefficients 8.15 for pyrene; 9.91 for PCB-101) than for the anthracite-based one (logarithmic Freundlich coefficients 7.20 and 9.70, respectively). In the presence of sediment, the opposite trend was observed, with the stronger sorption for anthracite-based AC. Thus, the presence of competing and/or pore-blocking sediment constituents reduces sorption to a larger extent for biomass-derived AC (factor of 5 for pyrene to almost 100 for PCB-101) than for anthracite-based AC (no reduction for pyrene to factor of 5 for PCB-101). This difference is tentatively attributed to the difference in pore size distribution, narrow pores being more prone to clogging, and could have implications for remediation feasibility with AC from different sources.
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| 2. |
- Cornelissen, Gerard, et al.
(författare)
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A large-scale field trial of thin-layer capping of PCDD/F-contaminated sediments : Sediment-to-water fluxes up to 5 years post-amendment
- 2016
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Ingår i: Integrated Environmental Assessment and Management. - : Wiley. - 1551-3777 .- 1551-3793. ; 12:2, s. 216-221
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Tidskriftsartikel (refereegranskat)abstract
- The longer-term effect (3-5 y) of thin-layer capping on in situ sediment-to-surface water fluxes was monitored in a large-scale field experiment in the polychlorinated dibenzodioxin and dibenzofuran (PCDD/F) contaminated Grenlandfjords, Norway (4 trial plots of 10000 to 40000 m(2) at 30 to 100 m water depth). Active caps (designed thickness 2.5 cm) were established in 2 fjords, consisting of dredged clean clay amended with powdered activated carbon (PAC) from anthracite. These active caps were compared to 2 nonactive caps in one of the fjords (designed thickness 5 cm) consisting of either clay only (i.e., without PAC) or crushed limestone. Sediment-to-water PCDD/F fluxes were measured in situ using diffusion chambers. An earlier study showed that during the first 2 years after thin-layer capping, flux reductions relative to noncapped reference fields were more extensive at the fields capped with nonactive caps (70%-90%) than at the ones with PAC-containing caps (50%-60%). However, the present work shows that between 3 and 5 years after thin-layer capping, this trend was reversed and cap effectiveness in reducing fluxes was increasing to 80% to 90% for the PAC caps, whereas cap effectiveness of the nonactive caps decreased to 20% to 60%. The increasing effectiveness over time of PAC-containing active caps is explained by a combination of slow sediment-to-PAC mass transfer of PCDD/Fs and bioturbation by benthic organisms. The decreasing effectiveness of nonactive limestone and clay caps is explained by deposition of contaminated particles on top of the caps. The present field data indicate that the capping efficiency of thin active caps (i.e., enriched with PAC) can improve over time as a result of slow diffusive PCDD/F transfer from sediment to PAC particles and better mixing of the PAC by bioturbation. Integr Environ Assess Manag 2016;12:216-221.
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| 3. |
- Cornelissen, Gerard, et al.
(författare)
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Large-Scale Field Study on Thin-Layer Capping of Marine PCDD/F-Contaminated Sediments in Grenlandfjords, Norway : Physicochemical Effects
- 2012
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 46:21, s. 12030-12037
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Tidskriftsartikel (refereegranskat)abstract
- A large-scale field experiment on in situ thin-layer capping was carried out in the polychlorinated dibenzodioxin, and dibenzofuran (PCDD/F) contaminated Grenlandsfjords, Norway The main focus of the,trial Was to,test the effectiveness of active caps (targeted thickness of 2.5 cm) consisting of powdered activated carbon (AC) mixed into locally dredged clean clay. Nonactive caps (targed thickness of 5 cm) consisting of clay without, AC as well as crushed limestone were also tested Fields with areas of 10 000 to 40 000 m(2) were established at 30 to 100 m water depth. Auxiliary shaken laboratory batch experiments showed that 2% of the applied powdered AC substantially reduced PCDD/F porewater concentrations, by >90% for tetra-, penta- and hexa-clorinated congeners to 60-70% for octachlorinated ones. In situ AC profiles revealed that the AC was mixed into the sediment to 3 to 5 cm depth in 20 months. Only around 25% of the AC was found inside the pilot fields. Sediment-to-water PCDD/F fluxes measured by in situ diffusion chambers were significantly lower at the capped fields than at reference fields in the same fjord, reductions being largest for the limestone (50-90%) followed by clay (50-70%), and the AC + clay (60%). Also reductions in overlying aqueous PCDD/F concentrations measured by passive samplers were significant in most cases (20-40% reduction), probably because of the large size of the trial fields. The AC was less effective in the field than in the laboratory, probably due to prolonged sediment-to-AC mass transfer times for PCDD/Fs and field factors such as integrity of the cap, new deposition Of contaminated sediment particles, and bioturbation. The present field data indicate that slightly thicker layers of limestone and dredged clay can show as good physicochemical effectiveness as thin caps of AC mixed with clay, at least for PCDD/Fs during the first two years after cap placement.
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| 4. |
- Cornelissen, Gerard, et al.
(författare)
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Remediation of Contaminated Marine Sediment Using Thin-Layer Capping with Activated Carbon-A Field Experiment in Trondheim Harbor, Norway
- 2011
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 45:14, s. 6110-6116
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Tidskriftsartikel (refereegranskat)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 anew 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.
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| 5. |
- Dublet-Adli, Gabrielle, et al.
(författare)
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A trade-off in activated biochar capping of complex sediment contamination: reduced PAH transport at the cost of potential As mobilisation
- 2024
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Ingår i: Journal of Soils and Sediments. - : Springer Nature. - 1439-0108 .- 1614-7480. ; 24:1, s. 497-508
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The effect of thin-layer capping with activated biochar on sediment-to-water flux was investigated. For the first time, the diffusion of both polycyclic aromatic hydrocarbons (PAHs) and arsenic (As) were studied simultaneously. The fate of As was investigated, under successive dysoxic and oxic conditions, in order to assess and discuss potential trade-off effects when using biochar as an active sorbent for capping of multi-contaminated sediments.Methods: Sediments from the Bureå bay (Sweden), contaminated with PAH and metal elements including As and Hg, were capped with activated biochar and/or bentonite in simple microcosm test systems in the laboratory. The contaminant transport from sediment through the capping to water body was studied by sampling metals in the water phase above the cap over time, or PAH in a heptane layer over water, at regular time intervals.Results: Consistently with the limited previous studies, reductions were observed (e.g., 60–65% for 15-PAH, 100% for chrysene) in sediment-to-water PAH fluxes upon biochar-based thin-layer capping. However, the most important novel finding revealed ambiguous effects of biochar capping on redox-sensitive elements, in particular As. Under the microcosm conditions of the experiment, where pH was affected by the capping material, biochar treatments favoured As mobility under oxic conditions, directly and/or via effects on Fe speciation. While capping limited the diffusion of As under dysoxic conditions, this also favoured greater As mobility under oxic water conditions compared to no capping.Conclusion: Design and monitoring of capping of PAH contaminated sediments should account for potential negative effects on co-occurring contaminants.
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| 6. |
- Eek, Espen, et al.
(författare)
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Field Measurement of Diffusional Mass Transfer of HOCs at the Sediment-Water Interface
- 2010
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 44:17, s. 6752-6759
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Tidskriftsartikel (refereegranskat)abstract
- The sediment to water diffusive flux of PAHs and PCBs was measured under field conditions with a novel infinite-sink benthic flux chamber that deployed semipermeable membrane devices (SPMD) as a sorbing material. Fluxes were measured before and after in situ capping of sediments in Oslo Harbour with clean clay. The fluxes of native pyrene and PCB 52 from uncapped contaminated sediment measured with the flux chamber were 0.3-1.6 mu g m(-2) d(-1) and 2-8 ng m(-2) d(-1), respectively. Fluxes from the capped sediment were reduced by 93-97%. The in situ measured fluxes were compared to fluxes independently calculated from freely dissolved concentrations in pore water and overlying water, measured using equilibrium passive samplers, diffusive boundary layer (DBL) thickness, measured by an alabaster dissolution method and literature values of diffusion coefficients. Measured fluxes from the uncapped sediment agreed well with calculated fluxes, the median of the ratio of the measured flux over the calculated flux was 0.9 with an inter quartile range of 0.5-1.6.
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| 7. |
- Frogner-Kockum, Paul, et al.
(författare)
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CoGas-projektet : Utveckling av en provtagningsmetod för att mätaföroreningstransport med gasflöden från fiberbankar
- 2024
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- I CoGas projektet utvecklades en fältutrustning och en metod som möjliggör in-situ provtagning av gas från fiberbankar. Detta för att kunna kvantifiera utsläpp av växthusgaser och medföljande halvflyktiga föroreningar (kvicksilver (Hg) och persistenta organiska miljögifter (POP)) samt gasmedierad partikelresuspension. En övergripande målsättning är att kunna bidra med kunskap om hur olika typer av föroreningar transporteras och sprids från fiberbankar. Den nya provtagningsutrustningen användes vid tre fiberbankar i Västernorrland (Väja, Sandviken och Köpmanholmen) där både passiv och forcerad gasprovtagning testades. Vid passiv provtagning mättes det naturliga gasflödet under en längre tid för att mäta mängden växthusgaser och partiklar som sprids under naturliga förhållanden. Det gick dock inte att detektera POPs i gasen som samlades in med den passiva provtagningen. För att kunna extrahera större volymer gas per tidsenhet och för att kunna analysera halten Hg i gasen utvecklades en forcerad provtagningsmetod. Järnstänger monterades därför under provtagaren vilka penetrerade sedimentytan och skapade artificiella transportgångar. Studien visade att andelen metangas vid in-situ provtagning (52–76 %) överensstämde relativt väl med de halter som tidigare uppmätts i laboratoriestudier (56 %; Lehoux et al, 2021). Våra resultat indikerar dock att de sammanlagda utsläppen av växthusgaser (CO2-ekvivalenter) från fiberbankar är i storleksordningen 52 000 – 170 000 ton/år, en uppskattning som är 25–70 gånger lägre än tidigare uppskattat av Lehoux et al. (2021). Att det blir så pass stor skillnad bedöms bero på att man i den tidigare beräkningen baserad på en laboratoriestudie (Lehoux et al., 2021) inte tog hänsyn till att den biologiskt aktiva zonen för metanogener i fiberbankarna bara utgör de översta decimetrarna av fiberbankarna (Regnell et al, 2014). Genom att ta med hela fiberbanksmassan i sina beräkningar (Lehoux et al., 2021) fick de en kraftig överskattad uppskattning av växthusgasutsläppet från Sveriges fiberbankar. Fiberbankarna i Sverige bedöms dock ändå stå för betydande utsläpp av växthusgaser, motsvarande ca 10–30 % av utsläppen från Sveriges avfallsdeponier. Kvicksilverhalterna (Hg) var i genomsnitt 1,6 ng/m3 i Väja, 6,0 ng/m3 i Sandviken och 19 ng/m3 i Köpmanholmen. Hg(0)-halten i gasfasen vid Köpmanholmen är ca 15 gånger högre än bakgrundshalterna i luft (1,3 ng/m3, IVL 2023). Av analyserade POPs kunde endast hexaklorbensen (HCB) detekteras, vilket antas bero på att HCB är mer volatilt än de övriga. HCB- halterna i den insamlade gasen var i genomsnitt 2,7 ng/m3, (n = 5) vid Väja och 8,5 ng/m3, (n = 6) vid Köpmanholmen, vilket är ca 100–200 gånger högre än de HCB-halter som påträffas i bakgrundsluft (Bidleman et al., 2017). För både HCB och Hg följer halten i gasen halten i sedimentet. Fluxet av HCB och Hg i gasfas från fiberbankarna kan uppskattas utifrån föroreningskoncentrationen i gasen (provtagen med den forcerade metoden) och gasflödet (provtaget med den passiva metoden). Givet att det genomsnittliga gasflödet i de lyckade provtagningarna är representativt uppskattas HCB-flux för de båda fiberbankarna vid ostörda förhållanden till i genomsnitt 3,2 ng/m2/år (1,5 ng/m2/år för Väja och 4,7 ng/m2/år för Köpmanholmen). Det genomsnittliga Hg-fluxet beräknades vid ostörda förhållanden till 0,4 ng/m2/år vid Väja, 1,5 ng/m2/år vid Sandviken och 4,6 ng/m2/år vid Köpmanholmen. Föroreningsfluxet i gasfas bedöms därmed vara relativt begränsat vid naturliga förhållanden. Den gasmedierade partikelspridningen varierade mellan 17–49 mg/m2/dag för Väja och Sandviken men var högre i Köpmanholmen (> 200 mg/m2/dag vid båda provtagningstillfällena). Partiklarnas föroreningsinnehåll har inte kunnat analyseras inom ramen för projektet men vid fysisk störning av fiberbankssediment bedöms betydligt större mängder HCB och Hg, i både gasfas och bundet till partiklar, kunna frigöras, åtminstone under en kort tid. Detta behöver beaktas vid riskbedömning och val av åtgärder av förorenade fiberbankar.
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| 8. |
- Hale, Sarah E., et al.
(författare)
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The role of passive sampling in monitoring the environmental impacts of produced water discharges from the Norwegian oil and gas industry
- 2016
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Ingår i: Marine Pollution Bulletin. - : Elsevier BV. - 0025-326X .- 1879-3363. ; 111:1-2, s. 33-40
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Tidskriftsartikel (refereegranskat)abstract
- Stringent and periodic iteration of regulations related to the monitoring of chemical releases from the offshore oil and gas industry requires the use of ever changing, rapidly developing and technologically advancing techniques. Passive samplers play an important role in water column monitoring of produced water (PW) discharge to sea-water under Norwegian regulation, where they are used to; i) measure aqueous concentrations of pollutants, ii) quantify the exposure of caged organisms and investigate PW dispersal, and iii) validate dispersal models. This article summarises current Norwegian water column monitoring practice and identifies research and methodological gaps for the use of passive samplers in monitoring. The main gaps are; i) the range of passive samplers used should be extended, ii) differences observed in absolute concentrations accumulated by passive samplers and organisms should be understood, and iii) the link between PW discharge concentrations and observed acute and sub-lethal ecotoxicological end points in organisms should be investigated.
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| 9. |
- Josefsson, Sarah, 1976-, et al.
(författare)
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Capping efficiency of various carbonaceous and mineral materials for in situ remediation of marine sediments contaminated with PCDD/Fs, OCS and HCB
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The efficiency of various thin-layer capping materials in reducing the sediment-to-water flux and benthic organism bioaccumulation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), hexachlorobenzene (HCB) and octachlorostyrene (OCS) was investigated in a boxcosm experiment. The influence of cap layer thickness (0.5-5 cm) and different cap materials were tested using a three-factor experimental design. The capping materials consisted of a passive carrier (coarse or fine limestone material, or a marine clay sediment), and an active material (activated carbon (AC) or kraft lignin) to sequester the contaminants and decrease their bioavailability. Macrofauna was added to the boxes to get a semi-natural bioturbation. The sediment-to-water flux was measured using passive (SPMD) samplers, and the bioaccumulation by the surface-dwelling gastropod Hinia reticulata and the deep-burrowing polychaetes Nereis spp. was determined. Results showed substantial decreases in both flux and bioaccumulation as a result of thin-layer capping. The thickness of the capping layer and the choice of active material were important factors, while the use of different types of passive materials was not statistically significant for any of the observed endpoints. Flux and bioaccumulation decreased with increased cap thickness, and could be further decreased with addition of active material. Activated carbon was more efficient than lignin, and a ~90% reduction of the flux and bioaccumulation, compared to uncapped control sediment, could be achieved with 3 cm caps with 3.3% AC (g C/g ww clay). The reduction was generally larger in the surface-dwelling H. reticulata than in Nereis spp., and the magnitude of the reduction was frequently similar between Nereis spp. and sediment-to-water fluxes. The latter was interpreted to indicate a link between Nereis spp. bioirrigation and sediment-to-water fluxes. Furthermore, the reduction in sediment-to-water flux was dependent on the hydrophobicity of the congeners, with less hydrophobic congeners achieving a larger reduction than more hydrophobic congeners.
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| 10. |
- Josefsson, Sarah, et al.
(författare)
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Capping Efficiency of Various Carbonaceous and Mineral Materials for In Situ Remediation of Polychlorinated Dibenzo-p-dioxin and Dibenzofuran Contaminated Marine Sediments : Sediment-to-Water Fluxes and Bioaccumulation in Boxcosm Tests
- 2012
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 46:6, s. 3343-3351
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Tidskriftsartikel (refereegranskat)abstract
- The efficiency of thin-layer capping in reducing sediment-to-water fluxes and bioaccumulation of polychlorinated dibenzo-p-dioxins and dibenzofurans, hexachlorobenzene, and octachlorostyrene was investigated in a boxcosm experiment. The influence of cap thickness (0.5-5 cm) and different cap materials was tested using a three-factor experimental design. The cap materials consisted of a passive material (coarse or fine limestone or a marine clay) and an active material (activated carbon (AC) or kraft lignin) to sequester the contaminants. The cap thickness and the type of active material were significant factors, whereas no statistically significant effects of the type of passive material were observed. Sediment-to-water fluxes and bioaccumulation by the two test species, the surface-dwelling Nassarius nitidus and the deep-burrowing Nereis spp., decreased with increased cap thickness and with addition of active material. Activated carbon was more efficient than lignin, and a ∼90% reduction of fluxes and bioaccumulation was achieved with 3 cm caps with 3.3% AC. Small increases in fluxes with increased survival of Nereis spp. indicated that bioturbation by Nereis spp. affected the fluxes.
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| 11. |
- Mustajärvi, Lukas, et al.
(författare)
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How Important is Bioturbation for Sediment-to-Water Flux of Polycyclic Aromatic Hydrocarbons in the Baltic Sea?
- 2019
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Ingår i: Environmental Toxicology and Chemistry. - : Wiley. - 0730-7268 .- 1552-8618. ; 38:8, s. 1803-1810
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Tidskriftsartikel (refereegranskat)abstract
- In the present study a recently developed benthic flow-through chamber was used to assess the sediment-to-water flux of polycyclic aromatic hydrocarbons (PAHs) at 4 sites on the Swedish Baltic Sea coast. The flow-through chamber allows for assessment of the potential effect of bioturbation on the sediment-to-water flux of hydrophobic organic contaminants. The sediments at the 4 investigated sites have both varying contamination degree and densities of bioturbating organisms. The flux of individual PAHs measured with the flow-through chamber ranged between 21 and 510, 11 and 370, 3 and 9700, and 62 and 2300 ng m(-2) d(-1) for the 4 sites. To assess the potential effect of bioturbation on the sediment-to-water flux, 3 flow-through and closed chambers were deployed in parallel at each site. The activity of benthic organisms is attenuated or halted because of depletion of oxygen in closed benthic chambers. Therefore, the discrepancy in flux measured with the 2 different chamber designs was used as an indication of a possible effect of bioturbation. A potential effect of bioturbation on the sediment-to-water flux by a factor of 3 to 55 was observed at sites with a high density of bioturbating organisms (e.g., Marenzelleria spp., Monoporeia affinis, and Macoma balthica of approximately 860-1200 individuals m(-2)) but not at the site with much lower organism density (<200 individuals m(-2)). One site had a high organism density and a low potential effect of bioturbation, which we hypothesize to be caused by the dominance of oligochaetes/polychaetes at this site because worms (Marenzelleria spp.) reach deeper into the sediment than native crustaceans and mollusks.
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| 12. |
- Mustajärvi, Lukas, et al.
(författare)
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In situ benthic flow-through chambers to determine sediment-to-water fluxes of legacy hydrophobic organic contaminants
- 2017
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Ingår i: Environmental Pollution. - : Elsevier BV. - 0269-7491 .- 1873-6424. ; 231, s. 854-862
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Tidskriftsartikel (refereegranskat)abstract
- Contaminated sediment can release hydrophobic organic contaminants (HOCs) and thereby act as a secondary source of primarily legacy hazardous substances to the water column. There is therefore a need for assessments of the release of HOCs from contaminated sediment for prioritization of management actions. In situ assessment of HOC sediment-to-water flux is currently done with (closed) benthic flux chambers, which have a sampling time exceeding one month. During this time, the water inside the chamber is depleted of oxygen and the effect of bioturbation on the sediment-to-water release of HOCs is largely ignored. Here we present a novel benthic flux chamber, which measures sediment-to-water flux of legacy HOCs within days, and includes the effect of bioturbation since ambient oxygen levels inside the chamber are maintained by continuous pumping of water through the chamber. This chamber design allows for sediment-to-water flux measurements under more natural conditions. The chamber design was tested in a contaminated Baltic Sea bay. Measured fluxes were 62–2300 ng m−2 d−1 for individual polycyclic aromatic hydrocarbons (PAHs), and 5.5–150 ng m−2 d−1 for polychlorinated biphenyls (PCBs). These fluxes were 3–23 times (PAHs) and 12–74 times (PCBs) higher than fluxes measured with closed benthic chambers deployed in parallel at the same location. We hypothesize that the observed difference in HOC flux between the two chamber designs are partly an effect of bioturbation. This hypothesized effect of bioturbation was in accordance with literature data from experimental studies.
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| 13. |
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| 14. |
- Oen, Amy M. P., et al.
(författare)
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In Situ Measurement of PCB Pore Water Concentration Profiles in Activated Carbon-Amended Sediment Using Passive Samplers
- 2011
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 45:9, s. 4053-4059
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Tidskriftsartikel (refereegranskat)abstract
- Vertical pore water profiles of in situ PCBs were determined in a contaminated mudflat in San Francisco Bay, CA, 30 months after treatment using an activated carbon amendment in the upper layer of the sediment. Pore water concentrations were derived from concentrations of PCBs measured in two passive samplers; polyethylene (PE, 51 mu m thick) and polyoxymethylene (POM, 17 mu m thick) at different sediment depths. To calculate pore water concentrations from PCB contents in the passive samplers, an equilibrium approach and a first-order uptake model were applied, using five performance reference compounds to estimate pore water sampling rates. Vertical pore water profiles showed good agreement among the measurement and calculation methods with variations within a factor of 2, which seems reasonable for in situ measurements. The close agreements of pore water estimates for the two sampler materials (PE and POM) and the two methods used to translate uptake in samplers to pore water concentrations demonstrate the robustness and suitability of the passive sampling approach. The application of passive samplers in the sediment presents a promising method for site monitoring and remedial treatment evaluation of sorbent amendment or capping techniques that result in changes of pore water concentrations in the sediment subsurface.
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| 15. |
- Thorne Schaanning, Morten, et al.
(författare)
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Long-term effects of thin layer capping in the Grenland fjords, Norway : Reduced uptake of dioxins in passive samplers and sediment-dwelling organisms
- 2021
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Ingår i: Chemosphere. - : Elsevier BV. - 0045-6535 .- 1879-1298. ; 264
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Tidskriftsartikel (refereegranskat)abstract
- The Grenlandfjords in South East Norway are severely contaminated with dioxins from a magnesium smelter operated between 1950 and 2001. In 2009, the proposal of thin-layer capping as a potential mitigation method to reduce spreading of dioxins from the fjord sediments, resulted in the set-up of a large-scale field experiment in two fjord areas at 30 and 100 m depth. After capping, several investigations have been carried out to determine effects on benthic communities and bioavailability of dioxins. In this paper we present the results on uptake of dioxins and furans (PCDD/F) in passive samplers and two sediment-dwelling species exposed in boxcores collected from the test plots during four surveys between 2009 (after cap placement) and 2018. Sediment profile images (SPI) and analyses of dioxins revealed that the thin (1-5 cm) cap layers became buried beneath several centimeters of sediments resuspended from adjacent bottoms and deposited on the test plots after capping. Uptake reduction ratios (R) were calculated as dioxins accumulated in cores collected from capped sediments divided by dioxins accumulated in cores collected from uncapped reference sediments. Cap layers with dredged clay or crushed limestone had only short-term positive effect with R-values increasing to about 1.0 (no effect) 1-4 years after capping. In spite of the recontamination, cap layers with clay and activated carbon had significant long-term effects with R-values slowly increasing from 0.12-0.33 during the first three years to 0.39-0.46 in 2018, showing 54-61% reduced uptake of dioxins (PCDD/F-TE) nine years after capping with AC.
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