The role of soil arsenic fractionation in the bioaccessibility, transformation, and fate of arsenic in the presence of human gut microbiota

• Published in: Journal of hazardous materials 2021-01, Vol.401, p.123366-123366, Article 123366
• Main Authors: Yin, Naiyi, Li, Yunpeng, Cai, Xiaolin, Du, Huili, Wang, Pengfei, Han, Zeliang, Sun, Guoxin, Cui, Yanshan
• Format: Article
• Language: English
• Subjects: Arsenic; Arsenic - analysis; Contaminated soil; Gastrointestinal Microbiome; Human gut microbiota; Humans; Soil; Soil Pollutants - analysis; Speciation; X-Ray Absorption Spectroscopy; XANES analysis
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2020.123366

[Display omitted] •Amorphous and crystalline Fe/Al (hydr)oxides contributed to colon As bioaccessibility.•High degree of transformation was found as soluble As at higher bioaccessibility.•As transformation occurred mainly in the solid phase at lower bioaccessibility (< 5%).•Gut microbiota could transform As(V) associated with crystalline and sulfide minerals. Soil arsenic (As) fractionation and its bioaccessibility are two important factors in human health risk assessment. However, data related to the impact of As minerals on the bioaccessibility with human gut microbiota involvement are scarce. In this study, speciation analysis was determined using HPLC-ICP-MS and XANES after incubation with colon microbiota from human origin, in combination with sequential extraction. Significant increase of colon As bioaccessibility was contributed primarily from As associated with amorphous and crystalline Fe/Al (hydr)oxides. We found a high degree of transformation at higher bioaccessibility (ave. 40 % of total As), which was predominantly present as liquid-phase As. In contrast, As transformation occurred mainly in the solid phase at lower bioaccessibility (< 5%), especially for soils containing As-S species. XANES spectroscopy revealed that As(III) increased by about 20 % in soil residues. Finally, the excreted As may be predominantly in association with (alumino)silicate minerals by SEM-EDX. It inferred that the priority sequence in As transformation by human gut microbiota was dissolved As(V), As(V) sorbed to mineral surfaces, crystalline As(V)-bearing minerals and As sulfides. This study will shed new light on the role of As-bearing minerals in evaluating health risks from soil As exposure.