Greatly enhanced arsenic shoot assimilation in rice leads to elevated grain export: comparison with wheat and barley

摘要

The grains, shoot and soils of 173 commercially farmed grain crops (temperate rice, wheat and barley) were surveyed to investigate variation in the assimilation and translocation of As. Rice samples were obtained from the Camargue (France), Donana (Spain), Cadiz (Spain), California (USA), and Arkansas (USA). Wheat and barley were collected from Cornwall and Devon (England) and the east coast of Scotland. Transfer of As from soil to grain was an order of magnitude greater in rice than in wheat or barley despite lower rates of shoot to grain transfer. Grain As levels over 0. 60μg·g dry wt, comparable to the levels found in As contaminated districts of Bangladesh, were found in rice grown in paddy soil of around 10/μg·g. Some agricultural soils in the southwest of England had levels in excess of 200μg·g dry wt. However, the grain levels in wheat and barley never breached 0.55μg·g, suggesting very different As soil thresholds should be set for aerobic and anaerobic agrosystems.