4. ASSESSMENT OF SURFACE WATER QUALITY IN PHUNG HIEP DISTRICT, HAU GIANG PROVINCE, VIETNAM

Tóm tắt

The study aims to assess the current state of surface water quality in Phung Hiep district, Hau Giang province, Vietnam. Surface water quality data were collected at nine locations (PH1 - PH9) collected at a frequency of 4 times in the year 2020 (March, May, August and October), with surface water quality parameters included temperature, pH, dissolved oxygen (DO), total suspended solids (TSS), nitrite (N-NO₂^-), nitrate (N-NO₃^-), ammonium (N-NH₄⁺), orthophosphate (P-PO₄^3-), biochemical oxygen demand (BOD), chemical oxygen demand (COD), coliform and iron (Fe). Surface water quality is assessed by comparing with national technical regulation on surface water quality (QCVN 08-MT:2015/BTNMT, column A1) and by calculating the water quality index (WQI). The results showed that TSS, N-NO₂^-, N-NH₄⁺, P-PO₄^3-, BOD, COD, coliform, Fe exceeded the allowable limits of QCVN 08-MT:2015/BTNMT, column A1. DO was lower than the regulation while the water quality parameters of temperature, pH and N-NO₃^- were within the allowable limits. The water indicators of DO, TSS, N-NO₂^-, N-NO₃^-, N-NH₄⁺ in the dry season were higher than those in the rainy season while the remaining parameters such as P-PO₄^3-, BOD, COD, coliform and iron in the dry season were lower than those in the rainy season. The WQI values ranged from 24 - 85, showing that surface water quality in Phung Hiep area was poor - good; In which, PH6 location has the best water quality (WQI = 46 - 85); PH1 (May) and PH7 (August) had poor water quality, mainly due to organic matters, coliform and N-NO₂^-. Future study needs to investigate the causes of water pollution to have appropriate treatment solutions.