Greatly Enhanced Arsenic Shoot Assimilation in Rice Leads to Elevated Grain Levels Compared to Wheat and Barley

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• 作者：Paul N. Williams ; Antia Villada ; Claire Deacon ; Andrea Raab ; Jordi Figuerola ; Andrew J. Green ; Jö ; rg Feldmann ; Andrew A. Meharg
• 刊名：Environmental Science & Technology
• 出版年：2007
• 出版时间：October 1, 2007
• 年：2007
• 卷：41
• 期：19
• 页码：6854 - 6859
• 全文大小：261K
• 年卷期：v.41,no.19(October 1, 2007)
• ISSN：1520-5851

文摘

Paired grain, shoot, and soil of 173 individual sample setsof commercially farmed temperate rice, wheat, andbarley were surveyed to investigate variation in theassimilation and translocation of arsenic (As). Rice sampleswere obtained from the Carmargue (France), Doñana(Spain), Cadiz (Spain), California, and Arkansas. Wheatand barley were collected from Cornwall and Devon (England)and the east coast of Scotland. Transfer of As from soilto grain was an order of magnitude greater in rice than forwheat and barley, despite lower rates of shoot-to-graintransfer. Rice grain As levels over 0.60 g g^-1 d. wt werefound in rice grown in paddy soil of around only 10 gg^-1 As, showing that As in paddy soils is problematic withrespect to grain As levels. This is due to the high shoot/soil ratio of ~0.8 for rice compared to 0.2 and 0.1 for barleyand wheat, respectively. The differences in these transferratios are probably due to differences in As speciationand dynamics in anaerobic rice soils compared to aerobicsoils for barley and wheat. In rice, the export of As fromthe shoot to the grain appears to be under tight physiologicalcontrol as the grain/shoot ratio decreases by more thanan order of magnitude (from ~0.3 to 0.003 mg/kg) and as Aslevels in the shoots increase from 1 to 20 mg/kg. Adown regulation of shoot-to-grain export may occur inwheat and barley, but it was not detected at the shoot Aslevels found in this survey. Some agricultural soils insouthwestern England had levels in excess of 200 g g^-1d. wt, although the grain levels for wheat and barleynever breached 0.55 g g^-1 d. wt. These grain levels wereachieved in rice in soils with an order of magnitudelower As. Thus the risk posed by As in the human food-chain needs to be considered in the context of anaerobicverses aerobic ecosystems.