Changes of dissolved organic matter in soil-aquifer treatment system

The changes of fluorescence characteristics of dissolved organic matter (DOM) during laboratory-scale soil-aquifer treatment (SAT) soil columns were studied. Using XAD resins, DOM was fractionated into 5 fractions: hydrophobic acid (HPO-A), hydrophobic neutral (HPO-N), transphilic acid (TPI-A), transphilic neutral (TPI-N) and hydrophilic fraction (HPI). Aromatic protein-like fluorescent materials in TPI-N were preferentially removed during SAT. The raletive content of aromatic protein- and soluble microbial byproduct-like fluorescent materials in HPO-A, HPO-N, TPI-A and HPI increased as a result of SAT. The removal rates of fluorescent materials with three to five fused benzene rings and humic acid-like fluorescent materials with excitation wavelength/emission wavelength (λ_ex/λ_em) of 390~ 410nm/456~476nm in each DOM fraction during SAT were lower than those of organics (on average) comprising dissolved organic carbon (DOC) in corresponding fraction. Other fluorescent materials in different fractions exhibited distinct removal behavior.