Abstract
Soils, as well as paddy tissue samples, were collected in the Se-rich area of Jinhua County, Zhejiang Province, China. Sequential extraction procedure was used for selenium (Se) fractionation, including soluble Se, exchangeable Se, carbonate-bound Se, iron and manganese oxide-bound Se, humic acids-bound Se, organic matter-bound Se, and the residual Se fraction. The results showed that soluble Se, exchangeable Se, carbonate-bound Se, iron and manganese oxide-bound Se fractions accounted for less than 2% of the total Se, respectively. Organic matter-bound Se was the dominant fractions. The average concentrations (mg kg−1) of Se in the paddy tissues were 0.069 in seed, 0.263 in root, 0.09 in stalk, and 0.17 in leaf. The organic matter-bound Se had a significant indirect effect on Se accumulation in paddy tissues. In conclusion, organic matter-bound Se was an important fraction and source of plant Se in agricultural soil.
Highlights
Selenium (Se) has been recognized as an essential trace element for humans and animals [1] because of its critical role in organic antioxidant defense systems [2] and cancer prevention [3]
The only one sample contained extremely high concentration of Se, which were located at cropland with the concentration of 1.58 mg kg-1
Organic matter-bound Se accounted for the majority of total Se in soil
Summary
Selenium (Se) has been recognized as an essential trace element for humans and animals [1] because of its critical role in organic antioxidant defense systems [2] and cancer prevention [3]. In many regions worldwide, such as in central China, Finland, and Sweden, the estimated Se intake rate from food consumption is generally lower than the 40 μg per day recommended by the World Health Organization [45]. Se supplementation by spraying with Se-enriched fertilizers to increase Se concentrations in agricultural products are some prevalent approaches [7], for example, the crop plant and vegetation Se biofortification strategy in the UK [8] By contrast, it might be a more efficient and effective option to exploit Se-enriched food in soils naturally abundant in Se, which distribute in some certain regions of the world, such as Enshi and Ziyang, China [9,10], South Dakota, USA [11] and Punjab, India [12]. 10 to 30 mg/kg Se in soil from Ziyang County in Shaanxi Province, China has been reported [9], and soils containing more than 3.0 mg kg-1 total Se can be defined as excessive for human nutrition [13]
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