Soil Particle Size Fractioning and Pb and Cd Bioaccessibility on a Dirt Road Near Former Beneficiation and Smelting Plant

Author(s)

Kasemodel, Mariana Consiglio ; Silvestre Rodrigues, Valeria Guimaraes

• Document type: Journal article
• Source: WATER AIR AND SOIL POLLUTION; v. 233, n. 12, p. 17-pg., 2022-12-01.

Abstract

Bioaccessibility of lead (Pb) and cadmium (Cd) was conducted in soil samples collected from a dirt road that connects a former Pb and zinc (Zn) beneficiation and smelting plant in the city of Adrianopolis (Parana state, southern Brazil). Samples were taken in three sites (beneficiation plant, slag deposit, and near Adrianopolis downtown). Samples were air-dried and sieved (< 0.074, 0.074, 0.42, 0.589, 0.84, 1.00, 1.41, 2.00, 2.83, 3.36, 4.00, and 4.76 mm) and subjected to gastric bioaccessibility tests using 0.4 M glycine. The results were analyzed using the estimated daily intake (considering adult and child targets) and target hazard quotient (THQ) considering the exposure of 100 and 1700 mg day(-1). The concentration of bioaccessible Pb (0.00-2818.25 mg kg(-1)) was significantly higher than Cd (0.00-1.28 mg kg(-1)), with alarming concentrations predominantly in the finer particles near the slag deposit (< 2.83 mm) and the former beneficiation (< 0.589 mm). The bioaccessible fraction (BAFs) varied from 0 to 20.7% (Cd) and 0 to 126.7% (Pb). Considering the 100 mg day(-1) scenario, Pb is a key contaminant in the slag deposit sample, while in the 1700 mg day(-1) scenario, Pb is a key contaminant in the slag deposit and the beneficiation sample. The maximum soil and dust intake considering Pb and Cd bioaccessible concentration is critical in the deposit sample, where values varied from 12.8 to 1272.7 mg day(-1). The Pb gastric bioaccessible fraction is higher in finer fractions, and these fractions (especially, < 0.074 and 0.074 mm) are more subjected to adhering in the skin and being ingested, which represents a risk to the population that uses this dirt road. Oral bioaccessiblity in mining contaminated areas is usually conducted with fine or particulate matter, and the study with soil fractioning is rare. In this study, soil fractioning was used to verify the portions that are more subjected to Pb and Cd gastric bioaccessibility in a metal-contaminated area. The fine and coarse fractions present several risks according to the THQ, and in the case of incidental ingestion can pose a health risk. (AU)

• FAPESP's process: 14/07180-7 - Study of the soil contamination degree in the area of the former mining plant Plumbum (Adrianópolis, PR) due to the disposal of mining waste
• Grantee: Valéria Guimarães Silvestre Rodrigues
• Support Opportunities: Regular Research Grants