Accumulation of Perfluoroalkylated Substances in Oceanic Plankton

Abstract

The bioaccumulation of perfluoroalkylated substances (PFASs) in plankton has previously been evaluated only in freshwater and regional seas, but not for the large oligotrophic global oceans. Plankton samples from the tropical and subtropical Pacific, Atlantic and Indian Oceans were collected during the Malaspina 2010 circumnavigation expedition, and analyzed for 14 ionizable PFASs, including perfluorooctanoate (PFOA), perfluorooctanesulfonate (PFOS) and their respective linear and branched isomers. PFOA and PFOS concentrations in plankton ranged from 0.1 to 43 ng g and from 0.5 to 6.7 ng g, respectively. The relative abundance of branched PFOA in the northern hemisphere was correlated with distance to North America, consistent with the historical production and coherent with previously reported patterns in seawater. The plankton samples showing the highest PFOS concentrations also presented the largest relative abundances of branched PFOS, suggesting a selective cycling/fractionation of branched PFOS in the surface ocean mediated by plankton. Bioaccumulation factors (BAFs) for plankton were calculated for six PFASs, including short chain PFASs. PFASs Log BAFs (wet weight) ranged from 2.6 ± 0.8 for perfluorohexanesulfonic acid (PFHxS), to 4.4 ± 0.6 for perfluoroheptanoic acid (PFHpA). The vertical transport of PFASs due to the settling of organic matter bound PFAS (biological pump) was estimated from an organic matter settling fluxes climatology and the PFAS concentrations in plankton. The global average sinking fluxes were 0.8 ± 1.3 ng md for PFOA, and 1.1 ± 2.1 ng md for PFOS. The residence times of PFAS in the surface ocean, assuming the biological pump as the unique sink, showed a wide range of variability, from few years to millennia, depending on the sampling site and individual compound. Further process-based studies are needed to constrain the oceanic sink of PFAS.

Poly- and Perfluoroalkyl Substances in Seawater and Plankton from the Northwestern Atlantic Margin

“…5,6 PFAS concentrations in seawater and marine plankton drive accumulation in marine food webs. 7,8 Prior work has examined the distribution and composition of PFAS in seawater from different regions. [8][9][10][11][12][13][14][15][16] However, there is still limited understanding of the how temporal shifts in sources and biogeochemical processes affect uptake and accumulation of PFAS at the base of marine food webs.…”

“…7,8 Prior work has examined the distribution and composition of PFAS in seawater from different regions. [8][9][10][11][12][13][14][15][16] However, there is still limited understanding of the how temporal shifts in sources and biogeochemical processes affect uptake and accumulation of PFAS at the base of marine food webs. 8,17 Regulatory actions targeting legacy PFAS such as PFOS have led to shifts chemical production toward PFAS with shorter carbon chains and polyfluoroalkyl compounds.…”

Direct effects of organic pollutants on the growth and gene expression of the Baltic Sea model bacteriumRheinheimerasp.BAL341

“…For the perfluoroalkylated pollutants (PFOS and PFOA), there is very limited information on their influence on bacteria. Bioaccumulation and toxicological effects on zooplankton and phytoplankton have been described (Mhadhbi et al ., ; Casal et al ., ). The chemical bonds between the carbon and fluorine existing in PFOA and PFOS molecules are particularly strong, wherefore it is considered that the potential transformation of such molecules is extremely slow (Smart, ).…”

“…The chemical bonds between the carbon and fluorine existing in PFOA and PFOS molecules are particularly strong, wherefore it is considered that the potential transformation of such molecules is extremely slow (Smart, ). Although there are laboratory studies showing that these compounds can be catalysed by enzymatic systems (Liu and Mejia Avendano, ), there are so far no reports on microbial degradation of PFOS and PFOA compounds under natural conditions (Casal et al ., ). Furthermore, a recent attempt to study microbial degradation of PFOS and PFOA (and polyfluorinated homologues) in wastewater sludge showed no conclusive proof for microbial degradation (Ochoa‐Herrera et al ., ).…”

“…In the case of OPEs and PFOS, unfortunately, the total concentrations of P‐ and F‐containing pollutants from the complex mixture are unknown, thus we took the information from field studies quantifying selected compounds from each family. The proportion of the different families of pollutants was 1 PAH : 10 alkanes : 1 OPE : 1 PFOS : 0.5 PFOA, which approximately reflects the occurrence of pollutants usually found in open ocean and coastal areas (Stortini et al ., ; Gonzalez‐Gaya et al ., ; Casal et al ., ; Li et al ., ) although the concentrations can vary across regions (see references for details). The compounds included in the MIX mixture were chosen because previous research has shown that bacterial taxa have the ability to break down these compounds and use them as food source (Singh and Walker, ; Joye et al ., ; Vila‐Costa et al ., ).…”