Risk assessment and source apportionment of heavy metalloids from typical farmlands provinces in China

Abstract

Potentially toxic metals in farmland soil have recently become a significant environmental concern in China. In this study, the occurrence and distribution of eight (8) heavy metals (HMs) were investigated from 54 topsoil samples obtained across 18 provinces. Human health and ecological hazards associated with HMs were assessed through different risk characterization indices and their sources predicted. The statistically mean concentrations of HMs ranged from 0.08 to 70.05 mg kg−1, which were below the determined threshold values for agricultural lands according to the Chinese National Standard (GB 15618–2018). The respective ecological risk index (Eri) of HMs revealed that they posed a lower risk (Eri<40) but their potential cumulative ecological risk (RI) was determined as a considerable risk (300 ≤ RI < 600). Spatial distribution and heterogeneities of HMs were found to be highly concentrated in the southern parts (e.g., Yunnan, Guangdong) of China, particularly for Arsenic (As), Zinc (Zn), and Chromium (Cr). PMF model was found capable of efficiently elucidating respective sources of HMs across the studied provinces as most were impacted by geological/pedogenic and anthropogenic activities (e.g., agricultural, industrial discharge fallouts). Probabilistic health risk assessment indicated that the non-carcinogenic risk (NCR) and total carcinogenic risk (TCR) of HMs in both adults and children were low and acceptable.