Spectroscopic properties of dissolved humic substances - a reflection of land use history in a fen area

The elemental composition and spectroscopic properties of dissolved fulvic acids isolated from different sampling media (topsoil, ground and surface water) of a natural fen area (high portion of organic soils) were examined to reveal the effects of land use history. These effects need to be known if dissolved humic substances are to be a major factor in identifying the impact of present and future changes in land use. Dissolved fulvic acids (topsoil, groundwater) from highly degraded peatlands (due to a long-term agricultural use) exhibit lower C/N ratios, higher absorption in the UV spectra, and higher absorption at 1,620 cm−1 in the FTIR spectra compared with fulvic acids from relatively intact peatlands. These properties illustrate that long-term agricultural use with high inputs results in increased aromatic structures and a further humification of dissolved fulvic acids due to very strong peat decomposition compared with relatively intact peatlands. Synchronous fluorescence spectra also indicate the higher level of aromatic structures within fulvic acids isolated from sites with long-term agricultural use (high peat decomposition) compared with a land use history resulting in a lower peat decomposition. The different sources of fulvic acids in surface water (precipitation, runoff, interflow, groundwater) are the main reason for these effects not being detected in fulvic acids isolated from surface water. Short-term changes in land use characterized by a transition from crop farming to an unimproved grassland were found not to affect the spectroscopic properties of dissolved fulvic acids. A humification index deduced from the synchronous fluorescence spectra is proposed. We have strong evidence that dissolved humic substances indicate changes in the environmental conditions (both anthropogenic and natural) of wetlands with a high proportion of organic soils.

[1]  Martin Körschens,et al.  Turnover of soil organic matter (SOM) and long‐term balances — tools for evaluating sustainable productivity of soils , 1998 .

[2]  K. Pihlaja,et al.  Isolation and characterization of natural organic matter from lake water: Comparison of isolation with solid adsorption and tangential membrane filtration , 1997 .

[3]  T. Miano,et al.  Humic-like Substances in Organic Amendments and Effects on Native Soil Humic Substances , 1996 .

[4]  Prediction of Properties of Soil Humic Substances from FTIR Spectra using Partial Least Squares Regression , 1998 .

[5]  M. Erich,et al.  Chemical characterization of dissolved organic matter released by limed and unlimed forest soil horizons , 1997 .

[6]  T. Moore,et al.  Sources and sinks of dissolved organic carbon in a forested swamp catchment , 1991 .

[7]  K. Kalbitz,et al.  Mobilization of heavy metals and arsenic in polluted wetland soils and its dependence on dissolved organic matter. , 1998, The Science of the total environment.

[8]  C. Cronan,et al.  Effects of disturbance and soil amendments on dissolved organic carbon and organic acidity in red pine forest floors , 1992 .

[9]  T. Miano,et al.  CHARACTERIZATION, DIFFERENTIATION, AND CLASSIFICATION OF HUMIC SUBSTANCES BY FLUORESCENCE SPECTROSCOPY , 1991 .

[10]  L. M. Shuman,et al.  Mobility of Zn, Cd and Pb in soils as affected by poultry litter extract--I. Leaching in soil columns. , 1997, Environmental pollution.

[11]  E. O’Loughlin,et al.  Molecular weight, polydispersity, and spectroscopic properties of aquatic humic substances. , 1994, Environmental science & technology.

[12]  G. W. Zellweger,et al.  Sorption of dissolved organic carbon by hydrous aluminum and iron oxides occurring at the confluence of deer creek with the Snake River, Summit County, Colorado , 1992 .

[13]  T. Miano,et al.  Spectroscopic and compositional comparative characterization of I.H.S.S. reference and standard fulvic and humic acids of various origin , 1989 .

[14]  I. Tegen,et al.  Mobilization of cesium in organic rich soils: Correlation with production of dissolved organic carbon , 1996, Water, Air, and Soil Pollution.

[15]  P. Hatcher,et al.  CHEMICAL COMPOSITION OF THE ORGANIC MATTER IN FOREST SOILS: 1. FOREST LITTER , 1988 .

[16]  L. McGown,et al.  Fluorescence Characterization of IHSS Humic Substances: Total Luminescence Spectra with Absorbance Correction , 1996 .

[17]  B. Christensen,et al.  Land‐use effects on the composition of organic matter in particle‐size separates of soil: I. Lignin and carbohydrate signature , 1994 .

[18]  D. F. Grigal,et al.  Molecular weight distribution of soluble organics from laboratory- manipulated surface soils , 1992 .

[19]  T. Shepherd,et al.  Effects of clay minerals and land use on organic matter pools , 1997 .

[20]  Baohua Gu,et al.  Adsorption and desorption of different organic matter fractions on iron oxide , 1995 .

[21]  N. Senesi.  Molecular and quantitative aspects of the chemistry of fulvic acid and its interactions with metal ions and organic chemicals : Part II. The fluorescence spectroscopy approach , 1990 .

[22]  P. Capriel.  Hydrophobicity of organic matter in arable soils: influence of management , 1997 .

[23]  John Doe,et al.  Soil Map of the World , 1962 .

[24]  E. Cotsaris,et al.  Seasonal changes in pathways of dissolved organic carbon through a hillslope soil (Xeralf) with contrasting texture , 1992 .

[25]  Patrick J. Mulholland,et al.  Dissolved Organic Matter Concentration and Flux in Streams , 1997, Journal of the North American Benthological Society.

[26]  D. McKnight,et al.  Geochemistry of aquatic humic substances in the Lake Fryxell Basin, Antarctica , 1996 .

[27]  G. Guggenberger,et al.  Factors controlling humification and mineralization of soil organic matter in the tropics , 1997 .

[28]  E. Thurman,et al.  Preparative isolation of aquatic humic substances. , 1981, Environmental science & technology.

[29]  J. McCarthy,et al.  Mechanisms of dissolved organic carbon adsorption on soil , 1989 .

[30]  T. Miano,et al.  Synchronous excitation fluorescence spectroscopy applied to soil humic substances chemistry , 1992 .

[31]  E. Thurman,et al.  Molecular size of aquatic humic substances , 1982 .

[32]  Klaus Kaiser,et al.  Dissolved organic matter sorption on sub soils and minerals studied by 13C‐NMR and DRIFT spectroscopy , 1997 .

[33]  V. Stolbovoi.  Soils of Russia: Correlated with the Revised Legend of the FAO Soil Map of the World and World Reference Base for Soil Resources , 1998 .

[34]  Hal O. Liechty,et al.  Dissolved organic carbon in northern hardwood stands with differing acidic inputs and temperature regimes , 1995 .

[35]  S. Schiff,et al.  Chemical Characteristics of Particulate, Colloidal, and Dissolved Organic Material in Loch Vale Watershed, Rocky Mountain National Park , 1997 .

[36]  F. J. Stevenson,et al.  Infrared spectra of humic acids and related substances , 1971 .

[37]  I. Kögel‐Knabner,et al.  Chemical composition of the organic matter in forest soils: The humus layer , 1988 .

[38]  K. Kreutzer.  Effects of forest liming on soil processes , 1995 .

[39]  J. Leenheer,et al.  Comprehensive approach to preparative isolation and fractionation of dissolved organic carbon from natural waters and wastewaters. , 1981, Environmental science & technology.

[40]  Á. Zsolnay.  Dissolved Humus in Soil Waters , 1996 .