[Characteristics of organic matter in different extractions of phosphorus forms in sediments in north part of Taihu Lake].
The characteristics of organic matter in different extractions of phosphorus forms in the surface sediments (0-10 cm) from three different regions of north part of Taihu Lake were investigated using the combination of high-performance size-exclusion chromatography (HPSEC), three-dimensional excitation/emission matrix (3DEEM) fluorescence spectroscopy, Fourier transform infrared spectroscopy (FTIR) and elemental analysis, and the relationship between organic matter and phosphorus was also discussed. The results show that the concentrations of total phosphorus in sediments coincide with the corresponding trophic level of overlying water. The atomic ratios of C/N (8.5-11.9) and C/P (188.5-256.6) indicate that organic matter in these sediments originated mainly from a lacustrine authigenic source, with minor terrestrial contribution. The molecular weight distribution and fluorescence spectroscopy of organic matter varied with different extractions, whereas the differences were not significant between sampling sites. The rank order of the molecular weight of organic matter in three kinds of extractions was: HCl > NaOH > NaHCO3, with M(w) and M(n) ranging from 4 983 to 5 873 and 3 642 to 5 065, 3 628 to 4 198 and 2 334 to 2 616, 3 282 to 3 512 and 2 249 to 2 380, respectively. These properties may suggest the composition of organic phosphorus and its bioavailability differs in different extractions. The fulvic acid-like (E(x)//E(m) = 230-260 nm/360-470 nm of peak A or E(x)/E(m) = 290-320 nm/390-460 nm of peak C) fluorophore was predominant in these extractions, while protein-like (E(x)/E(m) = 275-280 nm/340-360 nm of peak B and E(x)/ E(m) = 225 nm/330-350 nm of peak D) and humic acid-like (E(x)/E(m) = 360-375 nm/460-470 nm of peak E) fluorophores were observed in NaHCO3 and HCl extractions individually. Possibly indicates that the differences in the composition of organic matter and its decomposition in the sediment from Taihu Lake are subjected to resuspension. Moreover, the absorption of sedimentary humic acid from 1059 to 1 082 cm(-1) in the FTIR suggests that orthophosphate occurred in humic matrix.
Zhang
Run-Yu
RY
State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China. runyu_zhang@126.com
Wu
Feng-Chang
FC
Wang
Li-Ying
LY
Li
Wen
W
Wang
Jing
J
Mei
Yi
Y
D002681:China; D005068:Eutrophication; D005618:Fresh Water / Q000032:analysis*; D019015:Geologic Sediments / Q000737:chemistry*; D009930:Organic Chemicals / Q000032:analysis*; D010758:Phosphorus / Q000032:analysis / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis*
D009930:Organic Chemicals; D014874:Water Pollutants, Chemical; D010758:Phosphorus