The aim of this study was to investigate the accumulation of boron (B) in the soils, sediments, and plants in the wastewater (treated and untreated) irrigation farmlands. Twelve sites of soils and four sites of sediments were collected in two wastewater irrigation areas of Tianjin, China. Our results show that the long-term irrigation of wastewater induced B accumulation in the soils (81 - 90 mg kg-1 on average) and sediments (112 - 150 mg kg-1 on average). The readily available B fractions, salt extractable B and water extractable B, accounted for more than half of the extractable B. The plant available B in the soils exceeded toxic levels of most sensitive crops but B in plant leaves did not reach the thresholds. This study indicates that long-term irrigation of wastewater would induce excess accumulation of B in the soils of the farmlands and might pose a toxicity risk to the plants.
Keywords: Available boron; Boron fractions; Boron toxicity; Crop; Extractable boron.
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