Effect of phosphate on amorphous iron mineral generation and arsenic behavior in paddy soils.
Sci Total Environ
; 657: 644-656, 2019 Mar 20.
Article
en En
| MEDLINE
| ID: mdl-30677931
ABSTRACT
Arsenic (As) contamination was detected in paddy soils of Guangdong, China due to mining and weathering processes. Furthermore, As may be released into the soil and irrigation water during the application of phosphate (P). In this study, As behavior was assessed in three paddy soils (S6, S8 and TR) along the Hengshi river using batch and circular flow experiments with different phosphate application doses (0, 1, 5, 10, 50, 100â¯mg/L). The results indicate that pH variation (3-7) and higher phosphate concentrations in solution, can induce the release of As, with total As release ranked in the order S6â¯>â¯S8â¯>â¯TR. In addition, AsV was the main state affected by phosphate in the circular soil solution. In particular, after 7â¯days of P10 application, the highest As concentration in S6, S8 and TR soil solutions reached 2298.4, 829.9 and 153.9⯵g/L respectively, with the AsV state accounting for 93%, 97% and 18% of As. Some minerals were found to be generated in the middle container, most of which were amorphous iron or aluminum oxides and hydroxides, as confirmed by XRD. With mineral generation, the As concentration in soil solutions decreased to 314.2, 98.1 and 34.1⯵g/L. The SEM results indicate that the minerals became more fine (<100â¯nm) when more P was applied. In addition, XPS, SEM-eds and elemental analysis results also revealed that As distribution was closely associated with iron minerals. Along with soil depth, P influenced the state and distribution of iron minerals and As in the topsoil, while phosphate increased the available As and reduced the amorphous iron mineral content in the soil. Therefore, it is essential to evaluate As behavior in paddy soils, to monitor and avoid potential food security risks.
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Bases de datos:
MEDLINE
Idioma:
En
Revista:
Sci Total Environ
Año:
2019
Tipo del documento:
Article
País de afiliación:
China