Characterization of humic acids extracted from the sediments of the variousrivers and lakes in China
HE Mengchang , SHI Yehong , LIN Chunye
DOI:
Received December 07, 2007,Revised June 27, 2008, Accepted , Available online
Volume 20,2008,Pages 1294-1299
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The humic acids (HAs) isolated from the sediments of the various rivers, lakes, and reservoirs in China were studied using elemental
analyzer, fourier transform infrared (FT-IR), and CP/MAS 13C nuclear magnetic resonance (NMR) spectroscopy. The results showed
that the HAs were characterized by some common chemical and physicochemical properties, but they also pose some di erences in
the C-containing functional groups. The C/N, C/H, O/C, and O/H ratios di er widely for the various HAs, showing that the elemental
composition of the HAs from the various sediments was di erent due to the di erent environmental conditions. All HAs show similar
spectra with di erent intense absorbance in the region of 4000–2000 cm??1, suggesting that they have very similar structures and
functional groups. The absorbance region between 1900 and 400 cm??1 also showed similar spectra with di erent intense absorbance,
di erent relative intensities, and some relevant di erences for the various HAs. The total aromaticities for the six HAs varied from
23.1% to 41.8%. The di erences in the elemental composition and functional groups for the various HAs were attributed to their
di erent biogeochemical origins. The HAs in the sediments from Taihu Lake (one freshwater shallow lake with heavy eutrophication),
the Pearl River (the tropical river), and the Liao River (located at the joint of the temperate zone and cold-temperate zone) showed
di erent structural properties due to their di erent geographical and climate zones. These di erent properties for the six HAs were
expected to a ect the sorption, distributions, and fates of heavy metals and organic chemicals.
