Fluorescence Inner-Filtering Correction for Determining the Humification Index of Dissolved Organic Matter
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- 作者：Tsutomu Ohno
- 刊名：Environmental Science & Technology
- 出版年：2002
- 出版时间：February 15, 2002
- 年：2002
- 卷：36
- 期：4
- 页码：742 - 746
- 全文大小：60K
- 年卷期：v.36,no.4(February 15, 2002)
- ISSN：1520-5851
文摘
The use of fluorescence spectrometry has been suggestedas a simple method to determine the extent of naturalorganic matter humification by quantifying the red-shiftingof fluorescence emission that occurs with increasinghumification. Humification indices are calculated by dividingfluorescence intensity at longer wavelengths by intensityat shorter wavelengths. These indices calculated withoutany specific efforts to standardize dissolved organicmatter (DOM) concentration will result in index valuesthat vary with DOM concentration due to fluorescence inner-filtering effects. This study critically evaluated the effectof DOM concentration on humification index determinationusing organic matter isolated from field corn extract, soil:water extract, and soil fulvic acid. The results showthat humification index values are sensitive to DOMconcentration of the solution and are linear with respectto transmittance of the solution at the 254 nm used as theexcitation wavelength. An approximate correction forDOM is to exploit the linear nature of the regression fitand to determine index values at the extrapolated 100%transmittance value. An exact correction using explicitcorrection factors for both primary and secondary inner-filtration effects was shown to give humification index valuesthat are concentration invariant when absorbance of thesolution at 254 nm was less than approximately 0.3unit. Defining the humification index as the fluorescenceintensity in the 300
345 nm region divided by the sum ofintensity in the 300345 nm and 435480 nm regionswas statistically advantageous. This study suggests thatfor quantitative results which can be used to comparehumification of natural organic matter across different studies,correction of the fluorescence emission spectra for inner-filtration effects is needed.
345 nm region divided by the sum ofintensity in the 300345 nm and 435480 nm regionswas statistically advantageous. This study suggests thatfor quantitative results which can be used to comparehumification of natural organic matter across different studies,correction of the fluorescence emission spectra for inner-filtration effects is needed.