Spatial and Temporal Variation of Dissolved Heavy Metals in the Mun River, Northeast Thailand

Bin Liang,Kunhua Yang,Man Liu,Xiaoqiang Li,Chao Song,Guilin Han,Qian Zhang

doi:10.3390/w11020380

Abstract

River water samples between August 2017 (wet season) and March 2018 (dry season) from the Mun River Basin in northeast Thailand were collected and their dissolved heavy metals concentrations (Al, Mn, Fe, Cu, Zn, and Ba) were measured. Compared with international drinking water guidelines, Mn was the dominant pollutant in the dry season. The correlation analysis (CA) suggested that similar sources were shown in each element pair of Al-Fe, Mn-Zn, and Fe-Ba in both seasons. The principal component analysis (PCA) results showed that the dominant source of dissolved heavy metals was sedimentary inputs or colloid destabilization in the wet season, while anthropogenic inputs were the main sources in the dry season, such as agricultural runoff, industrial effluents, and domestic discharge. On the basis of water quality index (WQI), water at most sites in the wet and dry seasons can be categorized as excellent water, except for a few sites with substandard values. The river water posed no significant health risks according to the health risk assessment, but Mn, Fe, and Ba needed to be paid more attention due to the relatively high values. Al, Fe, and Ba were the main dissolved heavy metals flowing into the Mekong River, and Cu contributed to the background value in the Mekong river.

Highlights

Heavy metals are a global concern due to their effects on ecological risks to human health [1,2,3,4].heavy metals are difficult to be degraded or relieved of harmfulness through physical, chemical, or biological purification in natural environments [5], and can cause severe diseases, such as nervous disorders, visceral dysfunction, and cancers, through food chains [6,7]
The Kolmogorov-Smirnov (K-S) statistics were processed to test the normal distribution of the data [7], which indicated that only temperature is normally distributed with bilateral significance
Suggested that the mean values reflected the reliability of the data, due to the presence of outliers with extremely high or low values

Summary

Introduction

Heavy metals are a global concern due to their effects on ecological risks to human health [1,2,3,4].heavy metals are difficult to be degraded or relieved of harmfulness through physical, chemical, or biological purification in natural environments [5], and can cause severe diseases, such as nervous disorders, visceral dysfunction, and cancers, through food chains [6,7]. Heavy metals are a global concern due to their effects on ecological risks to human health [1,2,3,4]. Heavy metals in the dissolved phase are one of the most harmful substances that can directly affect the water quality of drinking water and irrigation water [8,9,10,11], and they are of greater toxicity than those in suspended and sedimentary phases [12,13,14]. In order to control water pollution and protect local water resources, it is of great significance to understand the spatial distribution, temporal variation, and sources of dissolved heavy metals, as well as the water quality and health risk level of water. Sources of dissolved heavy metals in the river may include emissions by industrial activities [7,15], urban construction [9,16], vehicle exhaust [17], etc

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Conclusion