Assessment and sources of heavy metals in suspended particulate matter in a tropical catchment, northeast Thailand

Since the suspended particulate matter (SPM) is a vital heavy metal transporter of the river systems, assessment of heavy metals contamination in SPM is significant as the first step of the high-efficiency surface water environment management and further foundation of water resources sustainability. However, this assessment is rare in developing countries (e.g., Thailand, agriculture is the main economic pillar). Fluvial heavy metal pollution prevention strategy is urgently required in these areas for reducing human exposure to metal contamination. For this purpose, the assessment of eight selected heavy metals of 52 SPM samples in a Thailand tropical river (Mun River) was conducted. The findings suggest that the contents of heavy metals in SPM are Mn (4616.7 mg kg(-1)) > Zn (223.9 mg kg(-1)) > V (109.1 mg kg(-1)) > Cr (100.1 mg kg(-1)) > Ni (51.0 mg kg(-1)) > Cu (27.6 mg kg(-1)) > Pb (14.3 mg kg(-1)) > Cd (10.7 mg kg(-1)). A relatively large proportion of heavy metals (e.g., Mn, 89.5%; Zn, 54.2%) are transported in suspended loads in Mun River. Heavy metals accumulation assessment suggests that Cd (EF = 17.5, I-geo = 3.7) and Mn (EF = 14.3, I-geo = 2.1) are extremely enriched in SPM, while the other metals are slightly enriched or not enriched. Principal component (PC) analysis extracted three PCs. PC 1 with a high loading of Mn, Zn, Cd, Pb reflecting these metals mainly from anthropogenic emissions, PC 2 (V and Cu) is primarily characterized by the natural sources (e.g., rock weathering), while PC 3 (Cr and Ni) can be defined as the result of combined action of natural and anthropogenic inputs. Risk assessment denotes that Cd is the major toxicity of SPM with a high toxic risk index (TRICd = 9.4, 54% of the total TRI) and the V, Cr, Mn, and Cd in SPM are the major exposure health risk, particularly for children (hazard index, HI > 0.1), more focus is required for these metals. In total, this study provides powerful support for the prevention of heavy metal pollution and the sustainability of water resources in the Mun River in such a developing country (Thailand).