Discrimination of Chemical Oxygen Demand Pollution in Surface Water Based on Visible Near-Infrared Spectroscopy

Chemical oxygen demand (COD) is one of the indicators used to monitor the level of pollution in surface water. To recycle agricultural water resources, it is crucial to monitor, in a timely manner, whether COD in surface water exceeds the agricultural water control standard. A diagnostic model of su...

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Main Authors: Xueqin Han, Xiaoyan Chen, Jinfang Ma, Jiaze Chen, Baiheng Xie, Wenhua Yin, Yanyan Yang, Wenchao Jia, Danping Xie, Furong Huang
Format: Article
Language:English
Published: MDPI AG 2022-09-01
Series:Water
Subjects:
Online Access:https://www.mdpi.com/2073-4441/14/19/3003
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author Xueqin Han
Xiaoyan Chen
Jinfang Ma
Jiaze Chen
Baiheng Xie
Wenhua Yin
Yanyan Yang
Wenchao Jia
Danping Xie
Furong Huang
author_facet Xueqin Han
Xiaoyan Chen
Jinfang Ma
Jiaze Chen
Baiheng Xie
Wenhua Yin
Yanyan Yang
Wenchao Jia
Danping Xie
Furong Huang
author_sort Xueqin Han
collection DOAJ
description Chemical oxygen demand (COD) is one of the indicators used to monitor the level of pollution in surface water. To recycle agricultural water resources, it is crucial to monitor, in a timely manner, whether COD in surface water exceeds the agricultural water control standard. A diagnostic model of surface water pollution was developed using visible near-infrared spectroscopy (Vis-NIR) combined with partial least squares discriminant analysis (PLS–DA). A total of 127 surface water samples were collected from Guangzhou, Guangdong, China. The COD content was measured using the potassium dichromate method. The spectra of the surface water samples were recorded using a Vis-NIR spectrometer, and the spectral data were pre-processed using four different methods. To improve the accuracy and simplicity of the model, the synthetic minority oversampling technique (SMOTE) and the competitive adaptive reweighted sampling (CARS) algorithm were used to enhance model performance. The best PLS–DA model achieved an accuracy of 88%, and the SMOTE–PLS–DA model had an accuracy of 94%. The SMOTE algorithm could improve the accuracy of the model despite the sampling imbalance. The CARS–SMOTE–PLS–DA model achieved 97% accuracy, and the CARS band selection technique improved the simplicity and accuracy of the discrimination model. The CARS–SMOTE–PLS–DA model improved the discrimination accuracy by 9% over that of the PLS–DA model. This method can not only save human and material resources but is also a new way for real-time online discrimination of COD in surface water.
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spelling doaj.art-dcb2ab9cf0394b3a8dd411967f34a7872023-11-23T22:14:09ZengMDPI AGWater2073-44412022-09-011419300310.3390/w14193003Discrimination of Chemical Oxygen Demand Pollution in Surface Water Based on Visible Near-Infrared SpectroscopyXueqin Han0Xiaoyan Chen1Jinfang Ma2Jiaze Chen3Baiheng Xie4Wenhua Yin5Yanyan Yang6Wenchao Jia7Danping Xie8Furong Huang9Opto-Electronic Department, Jinan University, Guangzhou 510632, ChinaState Environment Protection Key Laboratory of Water Environmental Simulation and Pollution Control, South China Institute of Environmental Sciences, Ministry of Ecology and Environment, Guangzhou 510655, ChinaOpto-Electronic Department, Jinan University, Guangzhou 510632, ChinaOpto-Electronic Department, Jinan University, Guangzhou 510632, ChinaOpto-Electronic Department, Jinan University, Guangzhou 510632, ChinaState Environment Protection Key Laboratory of Water Environmental Simulation and Pollution Control, South China Institute of Environmental Sciences, Ministry of Ecology and Environment, Guangzhou 510655, ChinaState Environment Protection Key Laboratory of Water Environmental Simulation and Pollution Control, South China Institute of Environmental Sciences, Ministry of Ecology and Environment, Guangzhou 510655, ChinaState Environment Protection Key Laboratory of Water Environmental Simulation and Pollution Control, South China Institute of Environmental Sciences, Ministry of Ecology and Environment, Guangzhou 510655, ChinaState Environment Protection Key Laboratory of Water Environmental Simulation and Pollution Control, South China Institute of Environmental Sciences, Ministry of Ecology and Environment, Guangzhou 510655, ChinaOpto-Electronic Department, Jinan University, Guangzhou 510632, ChinaChemical oxygen demand (COD) is one of the indicators used to monitor the level of pollution in surface water. To recycle agricultural water resources, it is crucial to monitor, in a timely manner, whether COD in surface water exceeds the agricultural water control standard. A diagnostic model of surface water pollution was developed using visible near-infrared spectroscopy (Vis-NIR) combined with partial least squares discriminant analysis (PLS–DA). A total of 127 surface water samples were collected from Guangzhou, Guangdong, China. The COD content was measured using the potassium dichromate method. The spectra of the surface water samples were recorded using a Vis-NIR spectrometer, and the spectral data were pre-processed using four different methods. To improve the accuracy and simplicity of the model, the synthetic minority oversampling technique (SMOTE) and the competitive adaptive reweighted sampling (CARS) algorithm were used to enhance model performance. The best PLS–DA model achieved an accuracy of 88%, and the SMOTE–PLS–DA model had an accuracy of 94%. The SMOTE algorithm could improve the accuracy of the model despite the sampling imbalance. The CARS–SMOTE–PLS–DA model achieved 97% accuracy, and the CARS band selection technique improved the simplicity and accuracy of the discrimination model. The CARS–SMOTE–PLS–DA model improved the discrimination accuracy by 9% over that of the PLS–DA model. This method can not only save human and material resources but is also a new way for real-time online discrimination of COD in surface water.https://www.mdpi.com/2073-4441/14/19/3003surface watervis-NIR spectroscopychemical oxygen demandSMOTECARSPLS–DA
spellingShingle Xueqin Han
Xiaoyan Chen
Jinfang Ma
Jiaze Chen
Baiheng Xie
Wenhua Yin
Yanyan Yang
Wenchao Jia
Danping Xie
Furong Huang
Discrimination of Chemical Oxygen Demand Pollution in Surface Water Based on Visible Near-Infrared Spectroscopy
Water
surface water
vis-NIR spectroscopy
chemical oxygen demand
SMOTE
CARS
PLS–DA
title Discrimination of Chemical Oxygen Demand Pollution in Surface Water Based on Visible Near-Infrared Spectroscopy
title_full Discrimination of Chemical Oxygen Demand Pollution in Surface Water Based on Visible Near-Infrared Spectroscopy
title_fullStr Discrimination of Chemical Oxygen Demand Pollution in Surface Water Based on Visible Near-Infrared Spectroscopy
title_full_unstemmed Discrimination of Chemical Oxygen Demand Pollution in Surface Water Based on Visible Near-Infrared Spectroscopy
title_short Discrimination of Chemical Oxygen Demand Pollution in Surface Water Based on Visible Near-Infrared Spectroscopy
title_sort discrimination of chemical oxygen demand pollution in surface water based on visible near infrared spectroscopy
topic surface water
vis-NIR spectroscopy
chemical oxygen demand
SMOTE
CARS
PLS–DA
url https://www.mdpi.com/2073-4441/14/19/3003
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