Effects of aluminum and soil mineralogy on arsenic bioaccessibility. (1st April 2021)

• Record Type: Journal Article
• Authors: Antônio, Daphne C.; Caldeira, Claudia L.; Freitas, Erico T.F.; Delbem, Itamar D.; Gasparon, Massimo; Olusegun, Sunday J.; Ciminelli, Virginia S.T.
• Is Part Of: Environmental pollution. Volume 274(2021)
• Publication Date: 2021-04-01
• Subjects: Arsenic bioaccessibility -- Soil characterization -- Al- -- Fe-(hydr)oxides -- Oriented aggregates; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2021.116482
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: A comprehensive characterization was performed to investigate the composition and mineralogy of soils from a gold mining region and their correlation with arsenic (As) total concentration and its bioaccessible fraction. The arsenic bioaccessible (BAC) fraction was determined through in vitro test and calculated as the ratio between the amounts of As released and the total As concentration in the soil sample. Among the minor constituents of environmental concern, only arsenic is significantly higher (median of 748.0 mg kg −1 ) than the national guidelines (agricultural, 35 mg kg −1 and residential, 55 mg kg −1 ). All the other trace elements showed concentrations below the investigation values established for residential areas. The mean bioaccessible As was 7.0 mg kg −1, with a median value of 4.4 mg kg −1, and a median As BAC percentage of 0.7%. The Brunauer–Emmett–Teller (BET) surface area showed a consistent increase with the increase of the acid-soluble Al content in the soil samples. The distribution of As in the soil samples is not correlated with the abundance of As-minerals and the fraction of adsorbed As. Arsenic was shown to be trapped in oriented aggregates of crystalline (Al-)Fe-(hydr)oxides nanoparticles (the main metalloid reservoirs), as demonstrated by scanning and transmission electron microscopy analyses. This unique pattern supports the significant difference between total As concentration and the bioaccessible amount. There was a positive correlation between soluble Al (within the Fe-(hydr)oxides phases and minor gibbsite) and As concentration in the soil samples, and a negative correlation with bioaccessible As. Therefore, although Al in the soil is associated with high As levels, it also makes the metalloid less bioaccessible. The risk to human health from As exposure to these soils is low. Graphical abstract: Image 1 Highlights: Soils with very high arsenic concentration - median of 748.0 mg kg −1 . Concentrations of other soil minor elements below the levels of concern. Low As bioaccessibility (4.4 mg kg −1 ) associated with acid-soluble aluminum. Arsenic trapped in oriented aggregates of (Al)Fe-(hydr)oxides nanoparticles. Low bioaccessibility implies low risk to As exposure. Abstract : The findings in this study indicate that the mineral phases associated with soluble Al contributed to the fixation of As and, in turn, the low BAC.