Analysis of Surface Water Quality in Upstream Province of Vietnamese Mekong Delta Using Multivariate Statistics

Abstract

The study employed different statistical approaches to assess surface water quality in the upstream region of the Vietnamese Mekong Delta. The dataset included seven parameters (i.e., temperature, pH, total suspended solids (TSS), five-day biological oxygen demand (BOD5), chemical oxygen demand (COD), ammonium nitrogen (NH4+-N) and coliform) at seventy-three locations. Cluster analysis (CA) and principal component analysis (PCA) were applied to analyze spatial variations in surface water quality and recognize the important parameters. The findings revealed that surface water quality was deteriorated by organic matters (high BOD5 and COD), nutrients and microorganisms. Particularly, urban areas were found to be more polluted than the other areas. The PCA results indicated that three potential water pollution sources, including industry, urban and tourism, could explain 87.03% of the total variance. Coliform was identified as the leading latent factor that controls surface water quality in the study area. CA grouped the sampling locations into 11 groups, in which the groups of the baseline monitoring sites and large rivers had better water quality. The results indicated a significant impact of anthropogenic activities (especially, urban and tourism practices) in surface water quality degradation. Moreover, CA suggested that the numbers of the sampling sites could be reduced from 73 to 58 locations, lowering 20.54% of the monitoring cost. Thus, the study recommends scrutinizing the current surface water quality monitoring system to be more economic and urgently implementing appropriate solutions to mitigate coliform pollution in the smaller water bodies.

Surface Water Quality in Urban Areas in Southern Most Province of Vietnam

“…At the same time, pH values were recorded similarly to the other water bodies of the Mekong Delta. In An Giang and Vinh Long provinces, the pH values fluctuated in the range of 7.15-7.22 and 7.08-7.94 respectively [12,27]. In addition, compared with previous studies in the water bodies of Ca Mau province, the pH value did not fluctuate much, still within the allowable limit of the standard [13,28].…”

“…Specifically, in the period 2017-2018, TSS concentrations were only recorded in the range of 50-221 mg/L. In addition, high TSS concentrations in the surface waters and exceeding the allowable limit of the standard were also recorded in many water bodies in the Mekong Delta such as Soc Trang, An Giang and Hau Giang Provinces with values of 95.79±8.45 mg/L, 53.33±3.59-59.59±8.82 mg/L and 53.6-73.6 mg/L, respectively [12,19,34] and TSS contamination of surface water is one of the main concerns of the region. TSS can clog fish gills, either killing them or reducing their growth rate [35].…”

“…In addition, this result shows that surface water in the study area is currently receiving a large amount of waste from livestock and domestic activities, especially excretory waste [45] and affect human health such as gastrointestinal diseases if using this polluted water source [46]. High levels of coliform and exceeding the allowable limit of QCVN 08-MT: 2015/BNTMT were recorded in many water areas in Vietnam such as the Uong river (10,810-16,800 MPN/100 mL) [38], Can Tho River in the period 2010-2011 (10,547-27,327 MPN/100 mL [47], the flowing Hau River through An Giang-Can Tho (14,200-31,500 MPN/100 mL) [45], water bodies in An Giang Province (11,067±2,168-31,363±11,476 MPN/100 mL) [12]. In general, surface water quality in the study area is affected by the activities of urban areas, residential areas, and market centers which have been polluted by organic and microorganisms with BOD 5 , COD and coliform is high in water.…”

“…Over the last few decades, useful tools for supporting water quality management have steadily increased, in which multivariate statistical analysis technique is considered as one of the most effective tools, has been widely used to assess changes in surface water quality [3]. Multivariate statistical techniques have been applied such as principal component analysis (PCA), hierarchical cluster analysis (HCA), correlation analysis (Pearson) and discriminant analysis (DA), interpreting complex databases, evaluating temporal and spatial variations in surface water quality, and identifying the potential sources of water contamination [9][10][11][12]. Ca Mau province is located in the southernmost part of the Mekong Delta, is within the seawater intrusion zone with a total area of 5,221.2 km 2 and a population of 1.23 million people.…”

Seasonal Variations in Groundwater Quality under Different Impacts Using Statistical Approaches

“…However, this analysis is only done in different aspects of hydrology. In addition, the approach to multivariate statistical analysis methods is mainly carried out for the surface water environment [24][25][26]. Up to now, there has been a lack of comprehensive studies on seasonal variations in groundwater quality in coastal provinces of the Mekong Delta, Vietnam.…”