Affiliations: College of Resources and Environmental Sciences,
Nanjing Agricultural University, Nanjing 210095 | College of Resources and Environmental Sciences,
Sichuan Agricultural University, Ya'an 625014, China
Abstract: Based on a modified Leenheer DOM fractionation scheme, fractionation
of DOM from the paddy soil was conducted by using XAD-8 resin into hydrophobic
bases (HOB), hydrophobic acids (HOA), acid-insoluble matter (AIM), hydrophobic
neutrals (HON) and hydrophilic matter (HIM). In total carbon content of DOM,
35.32% were the HIM and only 0.73% the HOB. However, HOA and AIM altogether
occupied 53.45%, while the HON fraction represented 10%. The sorption
experiments were conducted to determine the sorption capcity of pyrene on
unfractionated DOM and its fractions. Elemental analysis,
^1H-NMR and FTIR spectra were carried out on unfractionated
DOM and its fractions to examine the relationship between the structure of DOM
and partition coefficients (K_{oc}). The results showed that
HON had a greater affinity for binding pyrene than other fractions. While HON
was characterized by large long-chain alkylate (aliphatic structure). AIM
exhibited relative higher Koc values than HOA and HIM, due to much aromatic
structure in AIM, while the high content of carboxylic groups of HOA and HIM
depressed their binding capacity. This study demonstrates HON is a key
subcomponents of DOM in binding of pyrene, in other words, aliphalic structure
in DOM play a important role in binding of pyrene.
