title: Arsenic bioaccessibility in contaminated soils: Coupling in vitro assays with sequential and HNO3 extraction.
abstract: Arsenic bioaccessibility varies with in vitro methods and soils. Four assays including unified BARGE method (UBM), Solubility Bioaccessibility Research Consortium method (SBRC), in vitro gastrointestinal method (IVG), and physiologically based extraction test (PBET), were used to determine As bioaccessibility in 11 contaminated soils (22-4,172 mg kg(-1)). The objective was to understand how bioaccessible As by different methods was related to different As pools based on sequential extraction and 0.43 M HNO3 extraction. Arsenic bioaccessibility was 7.6-25, 2.3-49, 7.3-44, and 1.3-38% in gastric phase (GP), and 5.7-53, 0.46-33, 2.3-42, and 0.86-43% in intestinal phase (IP) for UBM, SBRC, IVG, and PBET, respectively, with HNO3-extractable As being 0.90-60%. Based on sequential extraction, As was primarily associated with amorphous (AF3; 17-79%) and crystallized Fe/Al oxides (CF4; 6.4-73%) while non-specifically sorbed (NS1), specifically sorbed (SS2), and residual fractions (RS5) were 0-10%, 3.4-20% and 3.2-25%. Significant correlation was found between As bioaccessibility by PBET and NS1+SS2 (R(2) = 0.55-0.69), and UBM-GP and NS1 + SS2 + AF3 (R(2) = 0.58), indicating PBET mostly targeted As in NS1+SS2 whereas UBM in NS1 + SS2 + AF3. HNO3-extractable As was correlated to bioaccessible As by four methods (R(2) = 0.42-0.72) with SBRC-GP having the best correlation. The fact that different methods targeted different As fractions in soils suggested the importance of validation by animal test. Our data suggested that HNO3 may have potential to determine bioaccessible As in soils.
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Jiangsu 210023, China.
authors.forename: Shi-Wei
authors.initials: SW
authors.lastname: Li
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Jiangsu 210023, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Li
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Jiangsu 210023, China.
authors.forename: Hong-Bo
authors.initials: HB
authors.lastname: Li
authors.affiliation: Centre for Environmental Risk Assessment and Remediation, University of Newcastle, Newcastle NSW2308, Australia.
authors.forename: Ravi
authors.initials: R
authors.lastname: Naidu
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Jiangsu 210023, China; Soil and Water Science Department, University of Florida, Gainesville, FL 32611, USA. Electronic address: lqma@ufl.edu.
authors.forename: L Q
authors.initials: LQ
authors.lastname: Ma
mesh_terms: D001151:Arsenic / Q000032:analysis*; D017942:Nitric Acid; D012987:Soil / Q000737:chemistry*
chemical_list: D012987:Soil; D017942:Nitric Acid; D001151:Arsenic
keywords: Arsenic; Bioaccessibility; Contaminated soil; HNO(3) extraction; Sequence extraction