采集中国红壤、黑土、褐土、棕壤和黄壤五种典型土壤，经一个月老化制备成浓度为600 mg·kg^-1的砷污染土壤样品，利用体外（in vitro）试验方法（PBET-UF模型）研究经口部摄入的土壤砷在人体胃肠道的生物可给性/生物有效性，并评估其健康风险，进而从土壤性质角度（包括土壤基本理化特性及砷的赋存形态）综合地探讨砷的生物可给性/生物有效性的影响因素，以分析不同土壤间差异的原因。结果表明，土壤砷在胃阶段的生物可给性为37.2%～71.8%，小肠阶段的生物可给性为49.0%～73.3%，小肠阶段的生物有效性为48.6%～72.1%，各类型土壤间差异极显著；土壤砷从胃到小肠是一个逐步被消化溶出的过程，且小肠中溶解态砷均可透过模拟小肠上皮细胞的专用超滤膜；各类型土壤经口部摄入的砷健康风险存在极显著差异，致癌风险和非致癌风险分别超过相应可接受限值两个数量级和一个数量级；此外，土壤砷的生物可给性/生物有效性与土壤pH、游离氧化铁铝含量、迁移系数_S及迁移系数_W存在显著或极显著相关性，迁移系数_S是影响土壤砷在胃阶段的生物可给性的主导因子，土壤pH为影响其在小肠阶段的生物可给性/生物有效性的主导因子，而游离氧化铁铝则主要通过与砷形成新矿物的方式降低其在土壤中的活性及生物可给性/生物有效性。本研究的成果将为后续开展更符合现实土壤污染情形的调查及重（类）金属污染土壤健康风险评估手段的完善做出积极贡献。

[Objective] This study aimed at accurate assessment of health risks of arsenic (As) in typical soils of China and comprehensive investigation of their influencing factors, based on oral bioaccessibility/bioavailability of soil As.[Method] Samples of five typical soils of the country, i.e. red soil, black soil, cinnamon soil, brown soil and yellow soil, were collected and prepared into As-contaminated samples by spiking As at 600 mg·kg^-1. After one-month aging, bioaccessibility/bioavailability of soil As in the gastrointestinal tract of a human being were studied, and its health risk was evaluated by means of in vitro test (PBET-UF model). Besides, from the perspective of soil properties (soil basic physicochemical properties and As fractions), influencing factors of As bioaccessibility/bioavailability were explored and variation of As bioaccessibility/bioavailability with the soil analyzed.[Result] Results show that As bioaccessibility/bioavailability significantly varied between soils, as As bioaccessibility ranged from 37.2% to 71.8% in the gastric phase and from 49.0% to 73.3% in the small intestinal phase, while As bioavailability in the small intestinal phase ranged from 48.6% to 72.1%. It was indicated that from the stomach to the small intestine soil As was gradually dissolved by digestive fluids, and almost all the dissolved As in the small intestine could pass through the specific ultrafiltration membrane used to simulate small intestinal epithelium. Also, health risks of soil As through oral ingestion significantly varied with the soil. Based on the estimated As bioaccessibility in the gastric phase, carcinogenic and non-carcinogenic risks of As in the five soils varied in the range of 4.28×10^-4~8.26×10^-4and in the range of 14.86~28.69, respectively; and based on the estimated As bioavailability in the small intestinal phase, they did in the range of 5.59×10^-4~8.30×10^-4and in the range of 19.40~28.81, respectively. The carcinogenic risk and non-carcinogenic risk was two orders and one order of magnitude respectively higher than their respective acceptable limit. In addition, correlation analysis shows that between bioaccessibility/bioavailability of soil As was significantly related to certain soil properties.[Conclusion] Oral bioaccessibility/bioavailability of soil As is significantly and positively related to soil pH, migration coefficient_S and migration coefficient_W, but negatively to content of free Fe and Al oxides. Migration coefficient_S is the main influencing factor determining bioaccessibility of soil As in the gastric phase, whereas soil pH is in the small intestinal phase. Although free Fe and Al oxides in the soils are not the determining factors directly affecting bioaccessibility/bioavailability of soil As in the gastric phase, they form new minerals with As, thus reducing the activity and consequent bioaccessibility/bioavailability of soil As. It is expected that all the findings in this study may contribute positively to making future field investigations of soil environmental quality of China more in line with the reality, and consummation of the methodologies for health risk assessment of heavy metal (loid) -contaminated soil.

X53;X820.4

国家自然科学基金项目（41807116）、福建省自然科学基金项目（2019J05035）和福建省中青年教师教育科研项目（JT180022）共同资助