Accumulation of arsenic in rice plant: a study of an arsenic-contaminated site in Taiwan

A study conducted in 2006 showed that over 100 ha of rice paddies in Beitou, Taiwan, irrigated over the years using water mixed with hot spring, was heavily polluted by arsenic. Thus, the objective of the present study is to measure arsenic content in different parts of rice and paddy soils, and eventually explain the arsenic distribution in ratoon rice, including its relationship to the soil. Arsenic levels of rice in grains, straws, roots, and soils were obtained from 15 rice paddies, selected based on different arsenic soil concentrations ranging from 67 to 438 mg kg−1 (n = 15). The mean arsenic content in grains was measured at 0.20 mg kg−1 (n = 60) and the highest grain arsenic of the survey was at 1.183 mg kg−1. Meanwhile, the mean total arsenic levels were 244 mg kg−1 (n = 28) in root and 4.4 mg kg−1 (n = 28) in straw. In comparison, regression of topsoil arsenic levels with rice grains (r2 = 0.00) and straws (r2 = 0.56) were less significant compared to that with rice roots (r2 = 0.93), and the mean arsenic level in rice from root to grain was also shown to have a decreasing trend. Though concentrations of arsenic in compositive rice grain each field did not exceed food hygiene concentration limit, arsenic level in root strongly depended on arsenic concentrations of soil suggesting that the high arsenic concentration may have the potential for translocation from root to grain which ultimately effects on the human health.