Unveiling the First Two Years Dataset on Atmospheric Deposition of Heavy Metals in Southern Vietnam Megacity: Potential Driving Factors and Ecological Risk Assessment

Abstract

Characterizing atmospheric deposition of heavy metals (HMs) through bulk sampling provides critical insights into environmental pollution patterns in fast-developing urban centers. Despite being a key economic hub in Southeast Asia (SEA), Ho Chi Minh City (HCMC) has received comparatively limited scientific attention regarding atmospheric deposition of HMs. This study reported the first 2-year (2023-2024) observation data of atmospheric deposition of HMs in HCMC. The volume-weighted mean (VWM) concentrations and deposition fluxes exhibits the same decreasing order: Zn (32.9 µg L-1; 59885 µg m-2 yr-1)>Mn (22.0; 40151)>Cu (2.16; 3872)>Pb (1.52; 2839)>Ni (0.70; 1271)>Cr (0.42; 765.7)>V (0.19; 349.4)>As (0.09; 173.7). Bulk HMs deposition fluxes increase during the rainy season as a result of enhanced rainfall, whereas the concentrations are lower (rainy < dry season), likely due to dilution effects. Seasonal variability in HMs deposition is strongly modulated by the East Asian monsoon through its combined influence on air-mass transport pathways and rainfall-driven scavenging. The enrichment factor (EF) and principal component analysis (PCA) identified four major potential contributing factors on rainwater characteristics at HCMC, including mixed between non-combustion traffic sources and industrial sources, combustion sources, crustal sources, and meteorological influences. Ecological risk assessments indicated low risk for most HMs (Ei<30), except Pb, which exhibits high risk (Ei=74.3) and accounts for 60% of the total potential ecological risk (PER=118.2), implicating industrial emissions as the dominant contributor. This work provides the first quantitative assessment of atmospheric HMs deposition in SEA, improving understanding of toxic metal inputs and informing environmental management in rapidly urbanizing areas.