Bromoanisoles and methoxylated bromodiphenyl ethers in macroalgae from Nordic coastal regions.

Marine macroalgae are used worldwide for human consumption, animal feed, cosmetics and agriculture. In addition to beneficial nutrients, macroalgae contain halogenated natural products (HNPs), some of which have toxic properties similar to those of well-known anthropogenic contaminants. Sixteen species of red, green and brown macroalgae were collected in 2017-2018 from coastal waters of the northern Baltic Sea, Sweden Atlantic and Norway Atlantic, and analyzed for bromoanisoles (BAs) and methoxylated bromodiphenyl ethers (MeO-BDEs). Target compounds were quantified by gas chromatography-low resolution mass spectrometry (GC-LRMS), with qualitative confirmation in selected species by GC-high resolution mass spectrometry (GC-HRMS). Quantified compounds were 2,4-diBA, 2,4,6-triBA, 2'-MeO-BDE68, 6-MeO-BDE47, and two tribromo-MeO-BDEs and one tetrabromo-MeO-BDE with unknown bromine substituent positions. Semiquantitative results for pentabromo-MeO-BDEs were also obtained for a few species by GC-HRMS. Three extraction methods were compared; soaking in methanol, soaking in methanol-dichloromethane, and blending with mixed solvents. Extraction yields of BAs did not differ significantly (p > 0.05) with the three methods and the two soaking methods gave equivalent yields of MeO-BDEs. Extraction efficiencies of MeO-BDEs were significantly lower using the blend method (p < 0.05). For reasons of simplicity and efficiency, the soaking methods are preferred. Concentrations varied by orders of magnitude among species: ∑2BAs 57 to 57 700 and ∑5MeO-BDEs < 10 to 476 pg g-1 wet weight (ww). Macroalgae standing out with ∑2BAs >1000 pg g-1 ww were Ascophyllum nodosum, Ceramium tenuicorne, Ceramium virgatum, Fucus radicans, Fucus serratus, Fucus vesiculosus, Saccharina latissima, Laminaria digitata, and Acrosiphonia/Spongomorpha sp. Species A. nodosum, C. tenuicorne, Chara virgata, F. radicans and F. vesiculosus (Sweden Atlantic only) had ∑5MeO-BDEs >100 pg g-1 ww. Profiles of individual compounds showed distinct differences among species and locations.

Industrial and natural compounds in filter-feeding black fly larvae and water in 3 tundra streams.

We report concentrations of polychlorinated biphenyls, polybrominated diphenyl ethers, novel flame retardants, and naturally occurring bromoanisoles in water and filter-feeding black fly (Simuliidae) larvae in 3 tundra streams in northern Sweden. The results demonstrate that black fly larvae accumulate a wide range of organic contaminants and can be used as bioindicators of water pollution in Arctic streams. Environ Toxicol Chem 2018;37:3011-3017. © 2018 SETAC.

Sorption of hydrophobic organic compounds to a diverse suite of carbonaceous materials with emphasis on biochar.

Carbonaceous materials like biochars are increasingly recognized as effective sorbent materials for sequestering organic pollutants. Here, we study sorption behavior of two common hydrophobic organic contaminants 2,2',5,5'-tetrachlorobiphenyl (CB52) and phenanthrene (PHE), on biochars and other carbonaceous materials (CM) produced at a wide range of conditions and temperatures from various feedstocks. The primary aim was to establish structure-reactivity relationships responsible for the observed variation in CM and biochar sorption characteristics. CM were characterized for their elemental composition, surface area, pore size distribution, aromaticity and thermal stability. Freundlich sorption coefficients for CB52 and PHE (i.e. LogK(F,CB52) and K(F,PHE), respectively) to CM showed a variation of two to three orders of magnitude, with LogK(F,CB52) ranging from 5.12 ± 0.38 to 8.01 ± 0.18 and LogK(F,PHE) from 5.18 ± 0.09 to 7.42 ± 1.09. The highest LogK(F) values were observed for the activated CM, however, non-activated biochars produced at high temperatures (>700 °C) sorbed almost as strongly (within 0.2-0.5 Log units) as the activated ones. Sorption coefficients significantly increased with pyrolysis temperature, CM surface area and pore volume, aromaticity, and thermal stability, and decreased with H/C, O/C, (O + N)/C content. The results of our study contribute to the understanding of processes underlying HOC sorption to CM and explore the potential of CM as engineered sorbents for environmental applications.

A synthesis of parameters related to the binding of neutral organic compounds to charcoal.

The sorption strength of neutral organic compounds to charcoal, also called biochar was reviewed and related to charcoal and compound properties. From 29 studies, 507 individual Freundlich sorption coefficients were compiled that covered the sorption strength of 107 organic contaminants. These sorption coefficients were converted into charcoal-water distribution coefficients (K(D)) at aqueous concentrations of 1 ng/L, 1 µg/L and 1 mg/L. Reported log K(D) values at 1 µg/L varied from 0.38 to 8.25 across all data. Variation was also observed within the compound classes; pesticides, herbicides and insecticides, PAHs, phthalates, halogenated organics, small organics, alcohols and PCBs. Five commonly reported variables; charcoal production temperature T, surface area SA, H/C and O/C ratios and organic compound octanol-water partitioning coefficient, were correlated with KD values using single and multiple-parameter linear regressions. The sorption strength of organic compounds to charcoals increased with increasing charcoal production temperature T, charcoal SA and organic pollutant octanol-water partitioning coefficient and decreased with increasing charcoal O/C ratio and charcoal H/C ratio. T was found to be correlated with SA (r(2) = 0.66) and O/C (r(2) = 0.50), particularly for charcoals produced from wood feedstocks (r(2) = 0.73 and 0.80, respectively). The resulting regression: log K(D)=(0.18 ± 0.06) log K(ow) + (5.74 ± 1.40) log T + (0.85 ± 0.15) log SA + (1.60 ± 0.29) log OC + (-0.89 ± 0.20) log HC + (-13.20 ± 3.69), r(2) = 0.60, root mean squared error = 0.95, n = 151 was obtained for all variables. This information can be used as an initial screening to identify charcoals for contaminated soil and sediment remediation.

Treatment of sites contaminated with perfluorinated compounds using biochar amendment.

Per- and polyfluorinated compounds (PFCs) have been attracting increasing attention due to their considerable persistence, bioaccumulation, and toxicity. Here, we studied the sorption behavior of three PFCs, viz. perfluorooctanesulfonic acid (PFOS), perfluorooctanecarboxylic acid (PFOA), perfluorohexanesulfonic acid (PFHxS), on one activated carbon (AC) and two biochars from different feedstocks, viz. mixed wood (MW) and paper mill waste (PMW). In addition, we explored the potential of remediating three natively PFC contaminated soils by the addition of AC or biochar. The sorption coefficient i.e. Freundlich coefficients LogKF, (µg/kg)/(µg/L)(n), for the two biochars were 4.61±0.11 and 4.41±0.05 for PFOS, 3.02±0.04 and 3.01±0.01 for PFOA, and 3.21±0.07 and 3.18±0.03 for PFHxS, respectively. The AC sorbed the PFCs so strongly that aqueous concentrations were reduced to below detection limits, implying that the LogKF values were above 5.60. Sorption capacities decreased in the order: AC>MW>PMW, which was consistent with the material's surface area and pore size distribution. PFC sorption to MW biochar was near-linear (Freundlich exponent nF of 0.87-0.90), but non-linear for PMW biochar (0.64-0.73). Addition of the AC to contaminated soils resulted in almost complete removal of PFCs from the water phase and a significant (i.e. 1-3 Log unit) increase in soil-water distribution coefficient LogKd. However, small to no reduction in pore water concentration, and no effect on LogKd was found for the biochars. We conclude that amendment with AC but not biochar can be a useful method for in situ remediation of PFC-contaminated soils.

Positioning activated carbon amendment technologies in a novel framework for sediment management.

Contaminated sediments can pose serious threats to human health and the environment by acting as a source of toxic chemicals. The amendment of contaminated sediments with strong sorbents like activated C (AC) is a rapidly developing strategy to manage contaminated sediments. To date, a great deal of attention has been paid to the technical and ecological features and implications of sediment remediation with AC, although science in this field still is rapidly evolving. This article aims to provide an update on the recent literature on these features, and provides a comparison of sediment remediation with AC to other sediment management options, emphasizing their full-scale application. First, a qualitative overview of advantages of current alternatives to remediate contaminated sediments is presented. Subsequently, AC treatment technology is critically reviewed, including current understanding of the effectiveness and ecological safety for the use of AC in natural systems. Finally, this information is used to provide a novel framework for supporting decisions concerning sediment remediation and beneficial reuse.

Equilibrium and kinetic modeling of contaminant immobilization by activated carbon amended to sediments in the field.

Addition of activated carbons (AC) to polluted sediments and soils is an attractive remediation technique aiming at reducing pore water concentrations of hydrophobic organic contaminants (HOCs). In this study, we present (pseudo-)equilibrium as well as kinetic parameters for sorption of a series of PAHs and PCBs to powdered and granular activated carbons (AC) after three different sediment treatments: sediment mixed with powdered AC (PAC), sediment mixed with granular AC (GAC), and addition of GAC followed by 2 d mixing and subsequent removal ('sediment stripping'). Remediation efficiency was assessed by quantifying fluxes of PAHs towards SPME passive samplers inserted in the sediment top layer, which showed that the efficiency decreased in the order of PAC > GAC stripping > GAC addition. Sorption was very strong to PAC, with Log KAC (L/kg) values up to 10.5. Log KAC values for GAC ranged from 6.3-7.1 and 4.8-6.2 for PAHs and PCBs, respectively. Log KAC values for GAC in the stripped sediment were 7.4-8.6 and 5.8-7.7 for PAH and PCB. Apparent first order adsorption rate constants for GAC (kGAC) in the stripping scenario were calculated with a first-order kinetic model and ranged from 1.6 × 10(-2) (PHE) to 1.7 × 10(-5) d(-1) (InP). Sorption affinity parameters did not change within 9 months post treatment, confirming the longer term effectiveness of AC in field applications for PAC and GAC.