Distribution of copper in soil and rice system of Hainan Island, China

This research aimed to discover the distribution and the primary influence factors of Cu in the soil-rice systems of tropical farmland. Soil samples of farmland and rice plant (stalk and polished rice) from the western region of Hainan Island were collected and studied. The results showed that the average Cu content in the topsoil of the study area was 15.75 mg kg(-1); the highest Cu content (45.92 mg kg(-1)) was found in the rice fields of the northern area, where pyroclastic parent material is distributed. Thus, there is a potential for Cu contamination of the rice grown in this region. The average contents of Cu in the rice stalks and polished rice were 16.9 and 5.68 mg kg(-1), respectively, indicating that the stalks had a larger capacity for Cu bioaccumulation than the polished rice. The bioaccumulation factor (BAF) of Cu in rice was found to decrease with increased Cu contents in the soil. In regards to the northern farmlands with high Cu contents in the soil derived from pyroclastic deposits, an alkaline fertilizer should be used to prevent the risk of Cu pollution in the polished rice, as soil acidification can promote the uptake and accumulation of Cu to some extent.