Abstract: Humic substrates are a major fraction of sediment
organic matters, and the sorption of hydrophobic organic chemicals by humic
substrates influences their behavior and fate in sediment. In this paper,
organic matters were divided into non-humic substrates and humic substrates.
Non-humic substrates include acid leaching fraction, acid extracted fraction,
and lipid; humic substrates were fractionated into Ca-binding-FA (fulvic acid),
Ca-binding-HA (humic acid), oxide-FA, oxide-HA, and humin. To study the effect
of organic fractions on sorption properties, sorption kinetic and equilibrium
sorption experiments of phenanthrene and pentachlorophenol (PCP) in five
sediments were carried out. The results showed that the contents of acid
leaching fraction and oxide-binding-HA were the main fractions to affect the
sorption rate constant, and for the sorption capacity of phenanthrene, humin
was the major fraction, followed by oxide-binding-HA, oxide-binding-FA, and so
on. While for PCP, the factors of influence on sorption capacity were mainly
CEC, Ca-binding-FA, and Ca-binding-HA.