Speciation and location of arsenic and antimony in rice samples around antimony mining area.

Arsenic (As) and antimony (Sb) are considered as priority environmental pollutants and their accumulation in crop plants particularly in rice has posed a great health risk. This study endeavored to investigate As and Sb contents in paired soil-rice samples obtained from Xikuangshan, the world largest active Sb mining region, situated in China, and to investigate As speciation and location in rice grains. The soil and rice samples were analyzed by coupling the wet chemistry, laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS), synchrotron-based micro X-ray fluorescence mapping (μ-XRF) and micro X-ray absorption near-edge structure (μ-XANES) spectroscopy. The results of field survey indicated that the paddy soil in the region was co-polluted by Sb (5.91–322.35 mg kg⁻¹) and As (0.01–57.21 mg kg⁻¹). Despite the higher Sb concentration in the soil, rice accumulated more As than Sb indicating the higher phytoavailability of As. Dimethylarsinic acid (DMA) was the predominant species (>60% on average) in the rice grains while the percentage of inorganic As species was 19%–63%. The μ-XRF mapping of the grain section revealed that the most of As was distributed and concentrated in rice husk, bran and embryo. Sb was distributed similarly to As but was not in the endosperm of rice grain based on LA-ICP-MS. The present results deepened our understanding of the As/Sb co-pollution and their association with the agricultural-product safety in the vicinity of Sb mining area. Image 1 • The pollution conditions of sites were classified as sub-polluted (III) or clear (I). • As and Sb contents in rice decreased in the order of root > shoot > husk > grain. • DMA was the predominant species in the rice grains. • As distributed on the periphery and the endosperm of the rice grain. • Sb accumulated on the periphery of the rice grain. This work clearly investigated the metalloid behaviors in soil-plant system, further contributing to address the food safety issues around the mining areas. [ABSTRACT FROM AUTHOR]

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