| 1. |
- Granberg, Maria E., 1971, et al.
(författare)
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Relative importance of macrofaunal burrows for the microbial mineralization of pyrene in marine sediments: impact of macrofaunal species and organic matter quality
- 2005
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Ingår i: Marine Ecology-Progress Series. - : Inter-Research Science Center. - 0171-8630 .- 1616-1599. ; 288, s. 59-74
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Tidskriftsartikel (refereegranskat)abstract
- The significance of macrofaunal burrows for microbial organic matter mineralization is well recognized. However, despite the importance of marine sediments as main sinks for organic particle-reactive contaminants such as polyaromatic hydrocarbons (PAHs), the significance of biogenic structures for microbial pollutant mineralization is largely unknown. We measured microbial mineralization of the PAH pyrene in different sediment compartments (surface, burrow and reduced bulk sediments) as a function of contamination history (uncontaminated and pyrene-exposed), macrofaunal species (Amphiura filiformis and Nereis diversicolor) and sediment organic matter quality (labile Tetraselmis sp. and refractory lignin). Sediments were exposed to combinations of the 3 factors for 43 d, after which sediment samples from the 3 compartments were incubated for radio-respirometric measurements in C-14-pyrene-coated flasks to monitor (CO2)-C-14 production (i.e. pyrene mineralization) for 128 d. Pyrene exposure enhanced microbial pyrene mineralization (MPM) rates by an order of magnitude in all compartments, signifying MPM as inducible. MPM rates increased successively from reduced bulk to burrow and surface sediments in uncontaminated treatments, while MPM rates were highest in burrows when exposed to pyrene. This emphasizes the oxygen dependence of MPM and pinpoints burrows as MPM hot spots. Enrichment with labile organic matter doubled MPM rates in pyrene-exposed surface sediment, likely fertilizing MPM where oxygen is readily available. Burrow sediment MPM rates were doubled with A, filiformis, suggesting species-specific stimulation of the microbial community within the burrows. In conclusion, burrow sediment appears to be at least as important as surface sediment for microbial PAH degradation in marine sediments. Furthermore, macrofaunal biodiversity, sedimentation events and the trophic state of the system should be taken into account when the fate and effects of organic contaminants are assessed in marine systems.
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| 2. |
- Selck, H., et al.
(författare)
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Impact of sediment organic matter quality on the fate and effects of fluoranthene in the infaunal brittle star Amphiura filiformis
- 2005
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Ingår i: Marine Environmental Research. - : Elsevier BV. - 0141-1136. ; 59:1, s. 19-45
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Tidskriftsartikel (refereegranskat)abstract
- Hydrophobic contaminants, such as polycyclic aromatic hydrocarbons (PAHs) readily adsorb to organic matter. The aim of this study was to determine the importance of the quality of sedimentary organic matter for the uptake, biotransformation and toxicity of the PAH, fluoranthene (Flu), in the infaunal brittle star Amphiura filiformis. Brittle stars were exposed to a base sediment covered by a 2 cm Flu-spiked top layer (30 mug Flu/g dry wt. sed.), enriched to the same total organic carbon content with either refractory or labile organic matter. The labile carbon source was concentrated green flagellate: Tetraselmis spp. The refractory carbon source was lignin from a paper mill. Tissue concentrations of Flu both in disk and arm-fractions were determined as total Flu, parent Flu (i.e. untransformed), aqueous Flu-metabolites, polar Flu-metabolites and tissue residue Flu (i.e. unextractable). Our results showed that sediment particle ingestion is a pathway by which Flu can enter benthic food webs. Flu toxicity (measured as arm-regeneration), but not net accumulation, was dependent on the nutritional quality of the ingested sediment particles. Flu bioaccumulation could not be attributed solely to equilibrium partitioning between organism lipid content and organic content of the sediment. Biotransformation of Flu by brittle stars was very limited and unaffected by organic matter quality. A. filiformis contributed to the downward transport of Flu from the surface sediment to the burrow lining. The limited breakdown of parent Flu by brittle stars and/or microorganisms was relatively higher in burrows compared to surface sediment, and highest in the presence of labile organic matter. Tissue concentrations were higher in disk than in arms, but the proportion of metabolic products relative to parent Flu was higher in arms than in the disk fraction. We estimate that the yearly mobilization of sediment-associated Flu by arm-regeneration in A. filiformis is in the range of 3.8-29.4 mug total Flu eq. m(-2) year(-1) at a sediment concentration of 30 mug Flu/g dry wt. sed. (C) 2004 Elsevier Ltd. All rights reserved.
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