Comment on "Fluorescence inner-filtering correction for determining the humification index of dissolved organic matter".
Comment on "Fluorescence inner-filtering correction for determining the humification index of dissolved organic matter".
复制标题
对“用于确定溶解有机物腐殖化指数的荧光内过滤校正”的评论。
DOI：
10.1021/es0200692
复制
发表时间：
2002
影响因子：
11.4
通讯作者：
Á. Zsolnay
中科院分区：
文献类型：
--
作者：
Á. Zsolnay
使用荧光光谱法已被建议作为一种简单的方法来确定天然有机质腐殖化的程度，通过量化的荧光发射的红移，发生增加腐殖化。腐殖化指数通过将较长波长处的荧光强度除以较短波长处的强度来计算。这些指数计算没有任何具体的努力，以标准化溶解有机物（DOM）浓度将导致指数值随DOM浓度变化，由于荧光内过滤效应。本研究主要评估了DOM浓度对土壤腐殖化指数测定的影响。结果表明，腐殖化指数对溶液中DOM浓度敏感，在254 nm激发波长处与溶液的透光率呈线性关系。DOM的近似校正是利用回归拟合的线性性质，并在外推的100%透射率值处确定指数值。一个精确的校正，使用显式校正因子的初级和二级内过滤效果，给出腐殖化指数值，浓度不变时，在254 nm处的溶液的吸光度小于约0.3个单位。将腐殖化指数定义为300→345 nm区域的荧光强度除以300→345 nm和435→480 nm区域的强度之和在统计学上是有利的。这项研究表明，定量结果，可用于比较腐殖化的天然有机物在不同的研究，校正的荧光发射光谱的内过滤效应是必要的。
The use of fluorescence spectrometry has been suggested as a simple method to determine the extent of natural organic matter humification by quantifying the red-shifting of fluorescence emission that occurs with increasing humification. Humification indices are calculated by dividing fluorescence intensity at longer wavelengths by intensity at shorter wavelengths. These indices calculated without any specific efforts to standardize dissolved organic matter (DOM) concentration will result in index values that vary with DOM concentration due to fluorescence inner-filtering effects. This study critically evaluated the effect of DOM concentration on humification index determination using organic matter isolated from field corn extract, soil:water extract, and soil fulvic acid. The results show that humification index values are sensitive to DOM concentration of the solution and are linear with respect to transmittance of the solution at the 254 nm used as the excitation wavelength. An approximate correction for DOM is to exploit the linear nature of the regression fit and to determine index values at the extrapolated 100% transmittance value. An exact correction using explicit correction factors for both primary and secondary inner-filtration effects was shown to give humification index values that are concentration invariant when absorbance of the solution at 254 nm was less than approximately 0.3 unit. Defining the humification index as the fluorescence intensity in the 300→345 nm region divided by the sum of intensity in the 300→345 nm and 435→480 nm regions was statistically advantageous. This study suggests that for quantitative results which can be used to compare humification of natural organic matter across different studies, correction of the fluorescence emission spectra for inner-filtration effects is needed.