Monitoring water quality of Cau river basin in Vietnam by “WATERit” technology

• Main Authors: Nguyen, Thi Thu-Hien, Doan, Thị Hoa-Huyen, Pham, Thi Tuyet-Nhung, Togo, Tatsuya, Katsuhiko-Tanaka, Nguyen, Hoang Viet-Phuong, Nguyen, Thi Anh-Tuyet
• Format: Conference Proceeding
• Language: English
• Subjects: Correlation coefficients; Equipment costs; Measurement methods; Monitoring; Nitrogen dioxide; Parameters; Quality assessment; River basins; Rivers; Surface water; Water quality
• ISSN: 0094-243X; 1551-7616
• DOI: 10.1063/5.0147989

Monitoring water quality in rivers requires a quick and high-accurate analysis method that requires a high number of representative points. To strengthen the monitoring capacity in the field, it is necessary to apply modern, compact, low-cost, and easy-to-use equipment. WATERit (WI) is a quick, and consistent water quality monitoring technology developed by OPTEX GROUP Co. Ltd in Japan, which has successfully demonstrated its feasibility and applicability for water quality monitoring in rivers. In this study, daily monitoring of 30 sites along the Cau River Basin was conducted to assess water quality of the Cau River Basin by WI for parameters: NH4+, NO2-, NO3-, and PO43-. A WI accuracy study was performed by repeating measurements on 30 sites with 2 machines over a 15-week period, and 10 sites with 3 machines over a 9-week period. Based on river water quality assessment, the range of NO2-, NO3-, NH4+, and PO43- oncentrations is 0.02 - 5.6/ 0.25 - 34.9/ 0.2 - 50/ 0.1 - 10.1 mg/L, exceeding National technical regulations on surface water quality (QCVN 08- 2015/BTNMT-column A2) of the total samples is 75.9%, 62.7%, 95.1%, and 50.8% respectively. The correlation coefficients of repeated measurement of 2 devices at 30 sites for 4 parameters were relatively high with 70 to 96.7% of the data having R2>0.75. Similarly, the relative standard deviation (RSD) of repeated measurements of 3 devices was greater than 89% of the data collected, which met the repeatability requirements according to Appendix F-AOAC for each concentration range. In addition, in our previous research, the correlation coefficients between the WI measurement method and standard method are recorded with an R2 ranging from 0.94-0.98. These results have proved WI’s accuracy and adaptability for monitoring of NO2-, NO3-, NH4+, and PO43- parameters in assessing river water quality in Vietnam.