Identifying Key Influences on Surface Water Quality in Freshwater Areas of the Vietnamese Mekong Delta from 2018 to 2020

Abstract

Urbanization, industrialization, and the loss of freshwater resources are leading to an increased awareness of the importance of surface water quality worldwide. Limited ground water resources, prolonged drouths, and flooding are creating pressure on the availability of freshwater sources in the Vietnamese Mekong Delta. However, the surface water quality in this region is measured mainly at the provincial level, without reference to the water quality of adjacent regions. In order to identify and understand the key factors that contribute significantly to the quality of surface water, it is necessary to consider the delta region as a holistic system and to systematically investigate the influence of different land uses on water quality. In this study, surface water quality was evaluated during the dry season, when flow is low and water exchange is limited. For this purpose, the temporal variation in the surface water quality of 12 water quality parameters at 132 monitoring stations was analyzed according to their surrounding type of land use. To further investigate the impact on low-hierarchy canals, a correlation analysis between the river and canal class hierarchy and all investigated water quality parameters was performed. The results show that surface water quality suffers particularly in the case of a low dissolved oxygen (DO) content, with a measured minimum of 0.48 mg/L, and in cases of organic pollution in the form of total suspended solids, biochemical oxygen demand, and chemical oxygen demand, with values up to 146 mg/L, 75.0 mg/L, and 41.0 mg/L, respectively. As the main factors influencing surface water pollution, freshwater aquaculture and industrial activities were identified. This could have a relevant impact on future sustainable land use planning.

Understanding watershed sources of pollution in Vinh Long Province, Vietnamese Mekong Delta

“…Cluster analysis (CA), principal component analysis (PCA), and multivariate regression statistics are also employed to assess the dynamics of surface water quality in spatial and temporal dimensions. These methods help identify correlations between different water quality indicators [21][22][23][24][25][26]. Other studies have used mathematical models to evaluate waste sources affecting the surface water quality of river basins [27][28][29].…”

Occurrence and Characteristics of Microplastics in Wild and Farmed Shrimps Collected from Cau Hai Lagoon, Central Vietnam

“…This finding is in line with that reported by Yan et al [ 32 ], who found a higher abundance of MPs in farmed shrimp compared to mostly wild aquatic creatures. Although all the wild and farmed shrimps lived in Cau Hai Lagoon, they might have been exposed to different water qualities and stagnant water conditions in farming areas and the wild environment, which are associated with aquatic contaminants, including microplastics [ 33 ]. It is noted that the detection frequency of MPs in the farmed shrimps was also higher than that in the wild shrimps.…”

Risks of Surface Water Pollution in Southern Vietnam

“…A previous study by Tuyet et al (2019) [25] also recorded high nutrient content in the water bodies of Ho Chi Minh City. This could be explained by incomplete nitrification due to the lack of oxygen in the water [26]. For heavy metals, the median concentrations of Pb and Cd met the regulated levels and suitable for the growth of aquatic species, whereas the median concentrations of Fe exceeded the regulated level.…”