Influences of multiwalled carbon nanotubes and plant residue chars on bioaccumulation of polycyclic aromatic hydrocarbons by Chironomus plumosus larvae in sediment

Abstract

Carbonaceous materials (CMs), including carbon nanotubes (CNTs), and black carbon have been suggested as potential remediation materials for hydrophobic organic contaminants (HOCs) in sediments or soils. However, the concentration-dependent and potential effects of CMs on the decrease in HOC bioavailability are not well understood. In this research, the effects of two types of multiwalled CNTs (MWNT-1 and MWNT-2) and chars (char-stalk produced from stalk and char-wood from wood) on the bioaccumulation of polycyclic aromatic hydrocarbons (PAHs), including phenanthrene, pyrene, and chrysene, in the benthic organism Chironomus plumosus larvae were studied. When CM content was 1.5% or less in sediments, biota-sediment accumulation factor (BSAF) values for PAHs decreased sharply as CM increased. However, when char and MWNT-1 content was greater than 1.5% in sediments, reduction rates of BSAF were slight. Furthermore, when MWNT-2 content was greater than 1.5%, BSAF values were elevated. This indicated that the MWNT-associated PAHs may have been absorbed by larvae through particle ingestion, and suggested that some CNTs may not be suitable for the remediation of HOC-contaminated sediments because they probably could increase the exposure risk of PAHs to benthic organisms, possibly because of their unique structure.

Bioaccumulation and ecotoxicity of carbon nanotubes

“…Addition of SWCNT to aquatic media significantly reduced bioaccumulation of HOC in deposit/suspension feeding polychaete Streblospio benedicti , while bioaccumulation in deposit-feeding meiobentic copepod Amphiascus tenuiremis was less affected [53]. Addition of MWCNT to sediment spiked with HOC or perfluorochemicals (PFC) reduced bioaccumulation of these chemicals in benthic developing larvae of Chironomus plumosus [73,74]. Both chemical types were removed most efficiently from the aqueous phase when MWCNT concentration was below 1.5% dry sediment weight.…”

“…Both chemical types were removed most efficiently from the aqueous phase when MWCNT concentration was below 1.5% dry sediment weight. At higher concentrations the bioaccumulation increased, probably because larvae ingested the MWCNT-associated pollutants [73,74]. In soil, the presence of SWCNT and MWCNT in high concentrations (3 g/kg) decreased pyrene bioaccumulation in a terrestrial polychaete Eisenia foetida , because CNT decreased uptake and increased PAH elimination [69].…”

Increasing evidence indicates low bioaccumulation of carbon nanotubes

“…In addition, we investigated the extent of CNT absorption across epithelial tissues and retention of CNTs among species. Other key topics such as general findings on the potential toxicity of CNTs to ecological receptors and humans 41–43 or the potential for carbon nanotubes to modify the bioaccumulation of co-contaminants 44–47 were not systematically reviewed in this study.…”

Importance of suspended sediment (SPS) composition and grain size in the bioavailability of SPS-associated pyrene to Daphnia magna

“…The detailed preparation and usage of polydimethylsiloxane-coated glass fibers can be found in our previous research . The pyrene sorbed on sediment and SPS samples were extracted using elution of hexane-dichloromethane (1:1 vol) with accelerated solvent extractor (Dionex ASE300) (Shen et al, 2012). Pyrene was analyzed with a Varian 3800 gas chromatography-4000 ion trap mass spectrometry (GC/MS) system equipped with a Varian Factor Four™ highly inert capillary column VF-5ms (30 m  0.25 mm diameter, and 0.25 mm film thickness).…”