Search

Metal(loid) contamination caused by industrial activities in agricultural soils has become a universal environmental and food safety concern. This study revealed the contamination, pathway, and source contribution of metal(loid)s such as lead (Pb), zinc (Zn) and cadmium (Cd) in maize and soils in different residential areas impacted by long-term historical artisanal zinc smelting activities from Southwest China. Results revealed that the soils were contaminated heavily by metals like Pb, Zn and Cd, with contents of 40–14,280, 150–47,020 and 1.28–61.7 mg/kg, respectively. Hazard quotients of food uptake for Pb, Cd and Cr in maize grains were extremely high for residents, in particular for the children. To trace the sources of metal health risk, lead isotope fingerprinting and binary mixing modeling were applied. It indicated that the anthropogenic activities contributed over 80% to the Pb contamination in maize grains. The findings highlighted warning levels of health risks to the residents in consuming maize grains in the historical artisanal Pb Zn smelting area. Therefore, an effective strategy including pollution source control and remediation measures must be taken to improve the soil quality and guarantee food safety around the historical smelting areas likewise. Unlabelled Image • Maize and rhizospheric soils were heavily contaminated by Pb, Zn and Cd. • Local residents were under high intake risks for Pb, Zn, Cd and Cr. • Pb-Zn artisanal smelting contributed over 80% to the contamination in the maize grains. • Lead isotopic source tracing is critical to address metal contamination inventory. [ABSTRACT FROM AUTHOR]

Farmland soil contamination of heavy metal(loid)s (HM) derived from smelting activities is a global concern, owing to its potential threat for human health through food chain. This study aims to evaluate total contents and bioavailability of HMs (Pb, Zn, Tl, Cd, Cu, As, Ag, Co, Cr and Ni) in farmland soils distributed over ten different villages from a former artisanal zinc smelting area in the northwest Guizhou province, China. The results showed that most of the studied soils still exhibited exceptionally high enrichment of Pb, Zn, Cd and As. High levels of bioavailable HMs were also observed in some samples, which may enter the human food chain through agricultural activities. Further analyses by Scanning Transmission Electron Microscopy - Energy Dispersive Spectroscopy (STEM-EDS), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) showed the presence of Zn smelting by-products such as Fe oxides, ZnO and PbSO 4 even in nanoscale particles retained by the soils. Elemental mapping by EDS confirmed a close association of the studied HMs with the smelting waste particles. All these results signify that high levels of HM-contamination from historical artisanal zinc smelting activities still persist and threaten the health of local residents, despite the fact that the major industrial-derived-contamination period ended >15 years ago. Our findings highlight pivotal concerns in similar artisanal-smelting-affected farmland soils of suspected contamination, due to less-expected toxic elements such as Tl, which may cause high ecological health risks. Unlabelled Image • The farmland soils in a historical artisanal zinc smelting area were intensively investigated. • Typical Heavy metal(loid)s in farmland soils from ten different villages were analyzed. • Most of the studied soils still exhibited exceptionally high enrichment of Pb, Zn, Cd and As. • Zn smelting derived Fe oxides, ZnO and PbSO 4 were found in nanoscale particles in the soils. • It indicates that artisanal-smelting activity may pose long-term pollution hazards. [ABSTRACT FROM AUTHOR]