Inner filter correction of dissolved organic matter fluorescence
Inner filter correction of dissolved organic matter fluorescence
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DOI：
10.4319/lom.2013.11.616
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发表时间：
2013-12-01
影响因子：
2.7
通讯作者：
Tranvik, Lars J.
中科院分区：
文献类型：
--
作者：
Kothawala, Dolly N.;Murphy, Kathleen R.;Tranvik, Lars J.
溶解有机物（DOM）的荧光被一种称为内滤效应（IFE）的自猝灭现象所抑制。尽管在地表水中广泛使用荧光来表征DOM，但IFE校正的优点和限制尚不明确。我们评估了常用的基于吸光度的方法（ABA）和最近提出的控制稀释方法（CDA）的有效性，以纠正IFE。校正荧光与总吸光度（A(total)）之间的线性关系；在四个样品的稀释系列中，整个激发-发射矩阵（EEM）的激发和发射波长吸光度之和表明，无论波长定位如何，ABA和CDA在1 cm细胞中的吸光度都至少为1.5。在信号与背景噪声（S/N）较低的eem区域，CDA校正比ABA校正的变异性更大。从ABA算法来看，当吸光度超过0.042时，显著的IFE（>5%）发生。在这些情况下，需要进行IFE校正，这是全国调查（n = 554）中绝大多数（97%）湖泊的情况。对于高吸收的样品，为了将吸光度降低到0.042以下，需要使用不希望的大稀释系数。对于A(Total) bbb1.5的罕见EEMs（瑞典调查中3.0%的湖泊），建议稀释2倍，然后进行ABA或CDA校正。本研究表明，对于绝大多数天然DOM样品，最常用的ABA算法无需事先稀释即可提供足够的校正。
The fluorescence of dissolved organic matter (DOM) is suppressed by a phenomenon of self-quenching known as the inner filter effect (IFE). Despite widespread use of fluorescence to characterize DOM in surface waters, the advantages and constraints of IFE correction are poorly defined. We assessed the effectiveness of a commonly used absorbance-based approach (ABA), and a recently proposed controlled dilution approach (CDA) to correct for IFE. Linearity between corrected fluorescence and total absorbance (A(Total); the sum of absorbance at excitation and emission wavelengths) across the full excitation-emission matrix (EEM) in dilution series of four samples indicated both ABA and CDA were effective to an absorbance of at least 1.5 in a 1 cm cell, regardless of wavelength positioning. In regions of the EEMs where signal to background noise (S/N) was low, CDA correction resulted in more variability than ABA correction. From the ABA algorithm, the onset of significant IFE (>5%) occurs when absorbance exceeds 0.042. In these cases, IFE correction is required, which was the case for the vast majority (97%) of lakes in a nationwide survey (n = 554). For highly absorbing samples, undesirably large dilution factors would be necessary to reduce absorbance below 0.042. For rare EEMs with A(Total) > 1.5 (3.0% of the lakes in the Swedish survey), a 2-fold dilution is recommended followed by ABA or CDA correction. This study shows that for the vast majority of natural DOM samples the most commonly applied ABA algorithm provides adequate correction without prior dilution.