Survey and assessment of surface water quality of the Hau River basin flowing through An Giang province in the dry season in the period of 2020 - 2022

Abstract

The research objective is to assess the surface water quality of the Hau River basin flowing through An Giang province in the dry season of March in the period of 2020 - 2022. Through 5 survey points and analysis of the surface water quality of Hau River flowing from An Phu district, Chau Doc city to Chau Phu district, the pH index fluctuates from 7.08 to 7.42, DO is 3.99 - 5.92 mg/l, TSS is 34 - 57 mg/l, COD is 12 - 23 mg/l, BOD₅ is 7 - 15 mg/l, Nitrate (N-NO₃^-) is 0.03 - 0.20 mg/l, Phosphate (P-PO₄^3-) is 0.00 - 0.92 mg/l, Ammonium (N-NH₄⁺) is 0.00 - 1.250 mg/l and Coliform is 4,300 - 46,000 MPN/100 ml. The above research results show that the surface water quality of the Hau River basin still has pH, Nitrate, and Phosphate indexes within the allowable limits. In particular, the Ammonium index exceeded the permissible standard at point 1 in 2021 and all 5 points in 2022. The cause of pollution was the impact of organic substances and microbial decomposition at points 1 and 2 upstream of the Phu Hoi River basin and the junction of the Chau Doc River with the river branch from Cambodia, point 3 residential area, and points 4 and 5 urban and industrial areas. The remaining indicators such as DO, TSS, COD, BOD_5, and Coliform increased beyond the permissible limit compared to the standards (QCVN 08-MT:2015/BTNMT, column A1), affecting aquatic life and human health if surface water of the Hau River basin is used directly without treatment.