Yin Naiyi, Li Yunpeng, Cai Xiaolin, Du Huili, Wang Pengfei, Han Zeliang, Sun Guoxin, Cui Yanshan
College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 101408, People's Republic of China; Research Center for Eco-Environment Sciences, Chinese Academy of Sciences, Beijing 100085, People's Republic of China.
College of Environment and Resources, Fuzhou University, Fujian, Fuzhou 350116, People's Republic of China.
J Hazard Mater. 2021 Jan 5;401:123366. doi: 10.1016/j.jhazmat.2020.123366. Epub 2020 Jul 3.
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.
土壤砷（As）的形态分析及其生物可利用性是人体健康风险评估中的两个重要因素。然而，关于含砷矿物在人体肠道微生物群参与下对生物可利用性影响的数据却很匮乏。在本研究中，在与源自人类的结肠微生物群孵育后，结合连续提取法，使用高效液相色谱 - 电感耦合等离子体质谱法（HPLC - ICP - MS）和X射线吸收近边结构光谱法（XANES）进行形态分析。结肠中砷生物可利用性的显著增加主要源于与无定形和结晶态铁/铝（氢）氧化物结合的砷。我们发现，在较高生物可利用性（平均占总砷的40%）时存在高度转化，主要以液相砷的形式存在。相比之下，在较低生物可利用性（<5%）时，砷的转化主要发生在固相，特别是对于含As - S物种的土壤。XANES光谱显示，土壤残渣中的As(III)增加了约20%。最后，通过扫描电子显微镜 - 能谱仪（SEM - EDX）推断，排泄出的砷可能主要与（铝）硅酸盐矿物结合。据推测，人体肠道微生物群使砷转化的优先顺序为溶解态As(V)、吸附在矿物表面的As(V)、含结晶态As(V)的矿物和硫化砷。本研究将为含砷矿物在评估土壤砷暴露健康风险中的作用提供新的见解。
