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7636801 
Journal Article 
Binding of Pyrene to Different Molecular Weight Fractions of Dissolved Organic Matter: Effects of Chemical Composition and Steric Conformation 
Wu Ji-zhou; Sun Hong-wen; Wang Cui-ping; Li Yong-hong; , 
2012 
Yes 
Chemical Research in Chinese Universities
ISSN: 1005-9040 
HIGHER EDUCATION PRESS 
BEIJING 
28 
4 
624-630 
English 
WOS:000308279600016 
The binding constant(K-DOM) of pyrene onto different molecular weight(M-w) fractions of a dissolved organic matter(DOM) extract from an estuarine sediment was measured via a fluorescence quenching method, and the possible binding mechanisms were discussed. The influence of water chemical parameters on pyrene binding was studied to elucidate the effects of DOM steric conformation. DOM fraction with larger M-w(>14000) showed a greater K-DOM(2.02x10(5)) than that with smaller M-w did, and the K(DOM)s were 1.16x10(5) and 1.13x10(5) for the fractions with M-w. of 1000-14000 and <1000, respectively. The K(DOM)s of different M-w DOM fractions were correlated positively with the atomic ratio of C/H and absorbance at 280 nm; while a negative correlation existed between K-DOM and (O+C)/N (atomic ratio), and K-DOM and O-containing groups. These correlations indicate the positive influence of aromatic structure and the negative effect of polarity on DOM binding capacity. Infrared spectroscopy revealed that specific interactions existed between pyrene and the DOM fraction with larger M-w besides hydrophobic partition, i.e., NH-pi-interaction in DOM moiety(1000-14000) and pi-pi electron donor acceptor(EDA) forces in DOM moiety (>14000). K-DOM varied in a complex pattern with increasing cation concentration and pH, which could be explained by the change in DOM steric conformation. Formed aggregates favored the lipophilic partition of pyrene. However, the accessibility to some interior binding sites became low when the aggregate was too large, leading to a reduced K-DOM. 
Binding constant; Conformation; Dissolved organic matter; Pyrene; Water chemistry