2011_02_23_Characterizing Dissolved Organic Matter Using PARAFAC Modeling of Fluore



ESEL Paper Review_20110223
 by Aamir Alaud-din

1.    Title and Author

Title: 2011_02_23_Characterizing Dissolved Organic Matter Using PARAFAC Modeling of Fluorescence Spectroscopy: A Comparison of Two Models
Authors: Jason B. Fellman*, Mathew P. Millera, Rose M. Coryb, David V. D’amorec, Dan Whited

*Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, Alaska 99775

aInstitute of Arctic and Alpine Research, University of Colorado, Boulder, Colorado 80309

bLos Alamos National Laboratory, Los Alamos, New Mexico 87544

cUSDA Forest Service, Pacific Northwest Research Station, Juneau, Alaska 99801

dInstitute of Northern Engineering, University of Alaska Fairbanks, Fairbanks, Alaska 99775

2.    Summary of Paper

This paper shows that an already existing model for PARAFAC analysis of excitation-emission matrices is an alternative to building a new model. For the sake of confirmation, 307 EEMs were fitted to an already existing Cory & McKnight (CM) model. Evaluation of residuals showed that 22 EEMs were fitted poorly by CM model. As a second test, correlation between percent contribution of PARAFAC components and dissolved organic matter (DOM) was studied. No significant difference was found between two models (p>0.05).
10 components were identified. The samples were collected from coastal temperature watersheds near Juneau, Alaska.
The following table shows the comparison of the two models viz., already existing CM model and the newly developed Alaskan (AK) model.
AK Model
(ex/em)    CM Model
(ex/em)    description    R2    p-Value
Comp 1
(240/450-470)    Comp 2
(250/450)    Q2    0.86    <0.001
Comp 2
(330/456)    Comp 1
(340/458)    humic-like    0.94    <0.001
Comp 3
(290/510)    Comp 5
(295/516)    SQ1    0.85    <0.001
Comp 4
(240/384)    Comp 12
(250/388)    Q3    0.76    <0.001
Comp 5
(340-410/ 440)    Comp 9
(345/410)    A    0.95    <0.001
Comp 6
(240/414)    missing from 
model    SQ3        
Comp 7
(275/462)    Comp 7
(270/462)    humic-like    0.95    <0.001
Comp 8
(295/416)    missing from
model    SQ2        
Comp 9
(270/306)    Comp 13
(280/<350)    humic-like    0.54    <0.001
Comp 10 
(280/336)    Comp 8
(270/<350)    tyrosine-like    0.70    <0.001
protein-like    protein-like    tryptophan-like    0.87    <0.001

Whether the previously existing model is suitable or developing a new model is a difficult question to answer. Previously existing model is recommended by the author.
3.    Contribution to ESEL

This paper showed the success of an already existing model. Since, there is no end in research, so, a motivation to build a universal model exists as is described by the author is his paper.

By: Aamir Alaud-din

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