Excitation−emission matrix (EEM) fluorescence spectroscopy has been widely used to characterize dissolved organic matter (DOM) in water and soil. However, interpreting the >10,000 wavelength-dependent fluorescence intensity data points represented in EEMs has posed a significant challenge. Fluorescence regional integration, a quantitative technique that integrates the volume beneath an EEM, was developed to analyze EEMs. EEMs were delineated into five excitation−emission regions based on fluorescence of model compounds, DOM fractions, and marine waters or freshwaters. Volumetric integration under the EEM within each region, normalized to the projected excitation−emission area within that region and dissolved organic carbon concentration, resulted in a normalized region-specific EEM volume (Φi,n). Solid-state carbon nuclear magnetic resonance (13C NMR), Fourier transform infrared (FTIR) analysis, ultraviolet−visible absorption spectra, and EEMs were obtained for standard Suwannee River fulvic acid and 15 h...

Fluorescence excitation-emission matrix regional integration to quantify spectra for dissolved organic matter.

Characterization of marine and terrestrial DOM in seawater using excitation-emission matrix spectroscopy

Spectroscopic characterization of the structural and functional properties of natural organic matter fractions

Soil chemists have long-recognized that knowledge of the elemental composition of soils is generally of little use in assessing the availability of these elements to plants. An obvious illustration of this principle is the common occurrence of Fe and Mn deficiency in plants despite the relatively high levels of Fe and Mn in many soils. For this reason, chemical soil tests have relied on measurement of extractable or “labile” fractions of elements. Such tests are empirical and provide little basis to relate metal extractability to the chemical forms of the metal in the soil. As soils are increasingly used in our society for purposes other than agriculture, the frequency and extent of soil contamination by toxic metals will increase. Empirical relationships may have to be replaced by a more fundamental understanding of the soil processes controlling metal solubility to prevent practices that could have deleterious effects on soil productivity and environmental quality.

Reactions controlling heavy metal solubility in soils

J.P. Martin

Papers

Flourescence Spectroscopy of Humic Substances

Comparative studies of pyrolysis-mass spectra of melanins, model phenolic polymers, and humic acids

Copper(II) and iron(III) complexation by soil humic acids: An IR and ESR study

Fluorescence spectroscopy of model humic acid-type polymers.