Factors of Soil Properties and Elements in Tissues Influencing on Extent of Arsenic Accumulation in Brown Rice

Abstract

Recently, As-contaminated soil management has started dealing with phytoavailable As content instead of total As content in soils. Phytoavailable As content is known to consider food safety more than the management of the environment. This study aims to predict As content in brown rice using phytoavailable As concentration in soil and soil properties and to see the relationship between element contents in tissues and As in brown rice. As-contaminated soils were collected, and their total and phytoavailable As content and soil properties were analyzed. Mehlich3 extraction method was used for phytoavailable As analysis. After the analysis, correlations among total and phytoavailable As concentrations in soils, As content in rice and soil properties were analyzed. Then, a prediction model of As content in brown rice was developed through multiple stepwise regression. Also, correlation analysis between nutrients and As contents in rice was conducted to identify the factors affecting As accumulation in brown rice. The modelling equation for estimating As concentration in brown rice was [Log (As in brown rice) = 2.45 + 0.13 × Log (As_Mehlich3) – 0.99 × Log (CEC) + 0.50 × Log (avail.-P)] (r = 0.49, p < 0.001). Soil avail.P concentration and CEC were valid variables for As accumulation in brown rice. In addition, Cu, Zn, Mo and Na in shoot were revealed to influence governing translocation of As from shoot to grain. Regression models for estimating As concentration in brown rice using total and phytoavailable As content in paddy soils, combined with soil avail.-P and CEC values. Parameter r p value Log (As_R†) = 2.98 ‒ 0.08×Log (Total As_S†) 0.13 0.318 Log (As_R) = 2.15 ‒ 0.06×Log (Total As_S) + 0.42×Log (avail.-P) 0.31 0.041 Log (As_R) = 2.63 + 0.01×Log (Total As_S) + 0.59×Log (avail.-P) ‒ 1.00×Log (CEC) 0.44 0.004 Log (As_R) = 2.15 + 0.17×Log (As_M3§) 0.28 0.022 Log (As_R) = 2.89 + 0.18×Log (As_M3) ‒ 0.72×Log (CEC) 0.38 0.008 Log (As_R) = 2.45+ 0.13×Log (As_M3) ‒ 0.99×Log (CEC) + 0.50×Log (avail.-P) 0.49 0.001 †As concentration in brown rice†Total As concentration in soil§Mehlich3-extractable As concentration in soil