Open access publications in the SLU publication database

Abstract

Per- and polyfluoroalkyl substances (PFASs) are persistent organic pollutants with bioaccumulative and toxic potential. This study investigated the levels, composition profiles and geographical distribution of 28 PFASs in 31 soil samples from Swedish background areas. In total, 15 of the 28 analysed PFASs were detected, with an average concentration of 2.4 ng g-1 dw (median of 1.9 ng g-1 dw, n = 31). The dominant PFASs in the soil samples were perfluorooctane sulfonic acid (PFOS) (20 % of the ∑28PFASs), perfluorooctane sulfonamidoacetic acid (FOSAA, 15 %), 6:2 fluorotelomer sulfonic acid (6:2 FTSA, 14 %) and perfluorobutane sulfonic acid (PFBS, 13 %). Perfluorooctane sulfonic acid (PFOS) had also the highest detection frequency of the studied PFASs (77 %) in the soil samples with a median concentration of 0.30 ng g-1 dw. However, the guideline value for PFOS in soil for sensitive land use from the Swedish Geotechnical Institute (SGI) (3 ng g-1 dw) was not exceeded in any sample. However, assuming the same toxicity for all PFASs, the ∑28PFAS concentrations exceeded the guideline value (3 ng g-1 dw) in 9 out of 31 samples (29 %). PFOS and perfluoroundecanoic acid (PFUnDA) concentrations showed higher concentrations towards the south (significant negative correlation with latitude; p < 0.05), while FOSAA showed an opposite trend (p < 0.05). Furthermore, PFBS showed higher concentrations towards the west (significant negative correlation with longitude; p < 0.05). The proportion of PFOS (%) decreased significantly with latitude (i.e. towards the south), while the proportion of FOSAA (%) increased with latitude (p < 0.05). Furthermore, the concentrations of FOSAA, PFBS and perfluorotridecanoic acid (PFTriDA) showed a significant positive correlation with total organic carbon (TOC) (p < 0.05). The concentrations of FOSAA correlated significantly positive with both PFTriDA and PFBS (p < 0.05). Overall, PFASs were ubiquitously detected in Swedish background soil samples and showed distinguish geographical distribution. However, more data are needed regarding the pathways and sources of PFASs in soil and identifying potential hot spots.