Poly- and perfluoroalkyl substances (PFASs) in sediment samples from Roodeplaat and Hartbeespoort Dams, South Africa

Abstract

This study aimed at determining PFAS concentrations in sediments obtained from two important water systems in South Africa, namely, the Roodeplaat and Hartbeespoort Dams. Sediment samples were collected in March and June representing summer and winter seasons. The analytes were extracted using the half-dry alkaline method followed by solid phase extraction and analysed with liquid chromatography-tandem mass spectrometry. The mean PFASs concentrations in Roodeplaat Dam (0.14–89.04 ng g−1) were significantly higher (p = 0.016) than in Hartbeespoort Dam (0.03–31.37 ng g−1). Perfluoro-n-decane sulfonic acid (PFDS), perfluoro-n-heptyl sulfonate (PFHpS), perfluoro-n-nonane sulfonic acid (PFNS) and perfluoro-n-octane sulfonic acid (PFOS) were the most dominant PFASs detected. PFASs were observed to be generally higher in summer compared to winter, however, the difference is statistically insignificant (p = 0.659). The perfluorosulfonic acids (PFSAs) was more dominant than the perfluorocarboxylic compounds, suggesting possible preferential usage of PFSAs in this region. These findings were different from reports from China and Korea, which reported long chain perfluorinated carboxylic acids (PFCAs) in sediments as the dominant PFASs. The results also revealed that the PFAS concentrations found in the present study were higher than the concentrations found in China, Germany, and Ethiopia but lower than the concentrations detected in the Western Cape Province in South Africa.

Keywords

• PFASs
• Concentrations
• Sediments
• Hartbeespoort and roodeplaat dams
• South Africa