|Farrow, Eric - Missouri University Of Science And Technology|
|Wang, Jianmin - Missouri University Of Science And Technology|
|Burken, Joel - Missouri University Of Science And Technology|
|Shi, Honglan - Missouri University Of Science And Technology|
|Yang, John - Lincoln University Of Missouri|
|Hua, Bin - Lincoln University Of Missouri|
|Deng, Baolin - University Of Missouri|
Submitted to: Ecotoxicology and Environmental Safety
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/14/2015
Publication Date: 4/21/2015
Citation: Farrow, E.M., Wang, J., Burken, J.G., Shi, H., Yan, W., Yang, J., Hua, B., Deng, B. 2015. Reducing arsenic accumulation in rice grain through iron oxide amendment. Ecotoxicology and Environmental Safety. 118:55-61. doi: 10.1016/j.ecoenv.2015.04.014.
Interpretive Summary: A recent survey of soil has identified elevated soil-arsenic (As) levels in the south central United States. Whether this due to natural geological formations or due to past agricultural practices is unclear. However because these soils overlap where the predominant US rice acreage is, there is concern how soil properties may impact accumulation of various elements in the rice grain. The accumulation of As and other elements of concern, such as selenium (Se), molybdenum (Mo), and cadmium (Cd), are heavily influenced by the mobility of these elements in soil, which may be further impacted by the application of crop fertilizers containing phosphate. We studied grain accumulation of As, Se, Mo and Cd as it relates to soil properties and to cultivars that differ in their response to straighthead, a physiological problem that is induced by As and results in dramatically reduced yields. Straighthead-resistant and straighthead-susceptible cultivars were grown in the soils treated with five levels of As, 4 levels of phosphate and 4 levels of iron oxide. Results demonstrated that both grain-As and grain-Se were positively correlated with soil-As. The straighthead resistant cultivar had significantly less grain-As but more grain-Se than the straighthead susceptible cultivar did. Conversely, grain-Mo and grain-Cd were not correlated with the soil-As. Application of phosphate had a minor impact on the grain accumulation of all these elements. However, iron oxide amendments significantly reduced grain-As and grain-Se. These results demonstrate that trace element concentrations in the rice grain can be manipulated by soil properties and choice of cultivar that will maximize benefits to human health.
Technical Abstract: In this research, we investigated the accumulation of arsenic (As), selenium (Se), molybdenum (Mo), and cadmium (Cd) in rice grain under different soil conditions in standard straighthead-resistant and straighthead-susceptible cultivars, Zhe 733 and Cocodrie, respectively. Results demonstrated that, both grain-As and grain-Se were positively and significantly correlated with soil-As for both cultivars. However, the straighthead resistant cultivar had significantly less grain-As but more grain-Se concentrations than the straighthead susceptible cultivar did. The resistant Zhe 733 accumulated 27%, 31%, 34%, 39%, 48%, and 58% less grain-As than the susceptible Cocodrie at soil-As levels of 5.9 (Native), 8.9, 11.9, 19.5 (the latter amended with MSMA, an arsenic based herbicide at, 20.9, and 25.9 mg kg-1) respectively. The grain-Mo and grain-Cd were not correlated with the soil-As. Results also indicated that phosphate application had very low impact on the grain accumulation of all these elements. However, iron oxide amendments significantly reduced grain-As and grain-Se. Therefore, soil-As affected not only grain accumulation of As, but also grain accumulation of Se, and the significance of this effect is interfered by the cultivar and soil properties associated with the mobility of soil As.