Leachability of PCBs in soil and its pH and dissolved organic matter (DOM) dependency
(English)Manuscript (preprint) (Other academic)
The leachability of eleven selected PCBs from naturally aged soil (Västervik, Sweden) was investigated in relation to the composition and concentration of dissolved organic matter at different pH (2 to 9), using a pH static test with initial acid/base addition. The batch leaching tests were performed on 50 g aliquots of a PCBs contaminated soil at a liquid to solid ratio (L/S) of 10 L/Kg. The PCBs were analyzed by gas chromatography coupled with high resolution mass spectrometry (GC-HRMS). The composition and of dissolved organic matter (DOM) at different pH values was explored by FTIR spectroscopy. The correlation between the FTIR data obtained for DOM and the log Kd values of PCBs was explored by orthogonal projections to latent structures (OPLS). The log Kd-values of all target PCBs decreased with increased pH values and the log Kd-values were highly correlated with the concentration of total organic carbon (TOC) in the leachates. For the lower chlorinated congener, PCB 28, this correlation was weaker. The variation of fractions of concentrations of mono-ortho to di-ortho PCBs (PCB 66 to PCB 52 and PCB 105 to PCB 101) indicated an influence of the ortho-chlorine atoms through pH effects on their leachability. The FTIR analysis of DOM showed that the least chlorinated and hydrophobic PCB congeners (i.e. PCB 28) might be associated with the hydrophilic fraction (i.e. carboxylic groups) of the DOM.
IdentifiersURN: urn:nbn:se:umu:diva-68377OAI: oai:DiVA.org:umu-68377DiVA: diva2:616638