Influence of Urban and Residential Areas on Surface Water Quality in the Vietnamese Mekong Delta Coastal Province

Abstract

This study was conducted to assess the impact of residential and urban activities on surface water quality in Ben Tre province in 2021. Water quality data were collected in the dry and rainy seasons at 15 locations for evaluating the parameters of temperature, pH, dissolved oxygen (DO), salinity, turbidity, biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), ammonium (N-NH4+), nitrate (N-NO3−), orthophosphate (P-PO43−), iron (Fe), coliform using national technical regulation on surface water quality (QCVN 08-MT: 2015/BTNMT, A1) and surface water quality index (VN_WQI). Principal component analysis (PCA) and cluster analysis (CA) methods were used to evaluate sampling sites and identify key parameters and potential pollution sources. The results showed that TSS, BOD, COD, N-NH4+, P-PO43−, Fe and coliform are pollutants significantly affect surface water quality in residential and urban areas. Salinity, nutrients, heavy metals and microorganisms had high values in the dry season, while turbidity, suspended solids, dissolved oxygen, and organic matter were higher in the rainy season. Water quality was assessed from moderate to very good indicated by VN_WQI index. PCA results revealed that five key factors explaining 87.2% of the variation and 12 main parameters (temperature, salinity, turbidity, TSS, DO, BOD, COD, N-NH4+, N-NO3−, P-PO43−, Fe and coliform) affecting water quality. CA results showed that the current monitoring locations can be reduced from 15 locations to 12 locations, which could save 20% of monitoring costs. Future study should focus on investigating concrete sources of water pollution for appropriate management measures.