污染农田茭白镉积累特点及茭白安全生产的土壤镉阈值OACSTPCD

To understand the characteristics of Cd uptake and accumulation by Zizania latifolia,57 pairs of Zizania latifolia organs(roots,short stems,leaves and fleshy stems)and topsoil samples were collected from Cd-polluted fields in Zhejiang Province to study the accumulation of Cd in different organs of Zizania latifolia and its relationship with soil Cd content.The results showed that Cd accumulated in different organs of Zizania latifolia decreased in the order of root＞short stem＞leaf＞fleshy stem.The average enrichment coefficients of Cd in root,short stem,leaf and fleshy stem were 1.553,0.675,0.222 and 0.077,respectively.Correlation analysis showed that Cd accumulated in different organs of Zizania latifolia was positively correlated with total soil Cd,and their correlation coefficients with various organs from high to low was root＞short stem＞leaf＞fleshy stem.The enrichment coefficients of Cd in various organs of Zizania latifolia decreased with the increase of soil pH value.A high proportion of Cd in roots was found in oxide iron-bound form,which indicated that the accumulated iron oxides on the root surface of Zizania latifolia could prevent Cd from entering into its aboveground part.The preliminary analysis showed that when the soil pH≤5.5,5.5＜pH≤6.5,6.5＜pH≤7.5,and corresponding total Cd content in the soils was below 1.00,1.25 and 2.00 mg/kg,respectively,the Cd content in the fleshy stem of Zizania latifolia was below 0.050 mg/kg,which could meet the requirements of safe production.The study showed that the edible part(fleshy stem)of Zizania latifolia had the characteristics of low Cd accumulation,which could be used as a substitute for rice in the farmland with medium and light Cd pollution.