0309_Composition analysis of colored dissolved organic matter in Taihu Lake based on three...

ESEL Paper Review_20110223 by Aamir Alaud-din

1.    Title and Author

Title: 2011_02_23_Composition analysis of colored dissolved organic matter in Taihu Lake based on three dimension excitation-emission fluorescence matrix and PARAFAC model, and the potential application in water quality modeling
Authors: WANG Zhi-gang11,2, LIU Wen-qing2,*, ZHAO Nan-jing2, LI Hong-bin2, ZHANG Yu-jun2, SI-MA Wei-cang2, LIU Jian-guo2

1School of Earth and Space Science, University of Science and Technology of China, Hefei 230026, China

2Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China

2.    Summary of Paper

Dissolved organic matter (DOM) mainly contains natural organic matter (NOM) and anthropogenic organic matter (AOM). Colored dissolved organic matter (CDOM) is a part of DOM. Taihu Lake is one of the five biggest lakes in China. Water samples from 26 different sites of Taihu Lake were collected and analysed by three dimensional excitation-emission matrix (3DEEM). Excitation and emission wavelength intervals were set to 5nm. CODCr and BOD5 were determined for all the samples. Core consistency diagnostic was used to choose the correct number of components. 

Table 1
    Number of Components
    1    2    3    4    5    6    7    8
Explained Variance (%)    85.7    95.6    97.5    98.4    98.7    99.1    99.3    99.5
Core Consistency (%)    100    99.7    60.4    46.8    17.9    4.2    3.0    0.8

Table 1 shows the variance of PARAFAC modeling and the core consistency diagnostic. It is obvious that number of components greater than three will make the model incorrect because core consistency fall below 50% for four components. A 3 component model shows PARAFAC modeling variance of 97.5% and core consistency of 60.4%.

All the three components showed the spatial variation. Site # 4 was found to be the most polluted. Relationship between wet chemical analysis and CDOM component scores is shown in Table 2. It is clear from the table that none of the CDOM components indicates the amount of gross organic matter. Moreover, all the three components contribute to BOD5 value which is an indicative of labile organic matter.
Table 2
    Component 1    Component 2    Component 3
COD    r=0.03611    n=26    r=0.0326    n=26    r=0.15828    n=26
BOD    r=0.72878    n=25    r=0.6471    n=25    r=0.53541    n=25

3.    Contribution to ESEL

Use of core consistency diagnostic is very helpful in finding the appropriate number of components for successful PARAFAC modeling. We can use some kind of water analysis with findings of PARAFAC model like wet analysis has been used in this paper for further findings.

By: Aamir Alaud-din
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