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Southeast Asia (SEA) faces significant environmental challenges due to rapid population growth and economic activity. Rivers in the region are major sources of plastic waste in oceans. Concerns about their contribution have grown, but knowledge of microplastics in the area is still limited. This article compares microplastic levels in sediment and water from urban zones of three major rivers in SEA: Chao Phraya River (Thailand), Saigon River (Vietnam), and Citarum River (Indonesia). The study reveals that in all three rivers, microplastics were found, with the highest concentrations in Chao Phraya’s water (80 ± 60 items/m3) and Saigon’s sediment (9167 ± 4559 items/kg). The variations in microplastic sizes and concentrations among these rivers may be attributed to environmental factors and the exposure duration of plastic to the environment. Since these rivers are important water supply sources, rigorous land-use regulations and raising public awareness are crucial to mitigate plastic and microplastic pollution. [ABSTRACT FROM AUTHOR]

Antibiotic resistance causes serious health problems associated with an increase in hospitalization time, treatment cost, and mortality. In this study, the contamination levels of antibiotic resistant bacteria were determined in the Saigon River, which is impacted by different anthropogenic activities in Ho Chi Minh City. Five target antibiotics were supplemented to the R2A medium at the concentration of amoxicillin (9.6 µg/ml) / clavulanic acid (4.8 µg/ml), amikacin (19.2 µg/ml), cefixime (1.2 µg/ml), ciprofloxacin (1.2 µg/ml), and trimethoprim (2.4 µg/ml)/ sulfamethoxazole (45.6 µg/ml). As the results, the antibiotic resistant bacteria were found in all the sampling sites and at the highest concentration at the sites impacted by wastewater from both industrial and residential activities. Enterobacteriaceae was the most abundant family with 23.8% of total isolates of the antibiotic resistant bacteria. Human opportunistic pathogens and pathogens such as Klebsiella pneumoniae (6.74%), Enterobacter sp. (4.15%), Escherichia coli (6.63%), Stenotrophomonas maltophilia (3.11%), Aeromonas Caviae (4.66%) were identified in all surface water samples. Correlation analysis suggested that the pollutions of dissolved salt, organic matter, and wastewaters may facilitate the antibiotic resistant bacteria in the aquatic environments. [ABSTRACT FROM AUTHOR]

The metal concentration in surface water of a river could be affected by season, position, and oceanic process such as tide. The current study aimed to (1) examine the heavy metal(loid) concentration in surface water from the Saigon River as affected by the combination of season, tide, and position and (2) apportion and quantify pollution sources. Ninety-six surface water samples were collected from 13 sites on the River in four campaigns (rainy season + ebb tide, rainy season + flood tide, dry season + ebb tide, and dry season + flood tide). Eight heavy metal(loid)s (Al, B, Bi, Fe, Mn, Pb, Sr, and Zn) were measured and subjected to multivariate analyses. Three-way ANOVA showed that in the rainy season, the total concentration of the metal(loid)s (TCM) in two tides was not clearly different from each other while in the dry season the TCM was significantly higher during the ebb tide than during the flood tide. Principal component analysis/factor analysis and Pearson correlation matrix showed that the TCM could be derived from three main sources, grouped into anthropogenic activities such as industrial, agricultural, and domestic wastes from inside Ho Chi Minh city, and natural origins from lowland area and acid sulfate soil. Three pollution sources explained 70% and 68% of the total variance of TCM in the rainy and dry seasons, respectively. In brief, the metal(loid) concentration was significantly affected by the season and tide and the pollution sources could be derived from inside Ho Chi Minh City and from lowland areas beyond the river estuary. [ABSTRACT FROM AUTHOR]