采用化学连续提取法研究了赫章铅锌矿冶炼区农田土壤以及马铃薯根、茎、叶、果实（块茎）中Cd含量及其化学形态分布特征，以揭示该污染区Cd在土壤与植物体内的迁移转化特征。结果表明，农田土壤Cd含量介于2.53～22.30 mg/kg，且以可交换态和铁锰氧化物结合态为主，土壤p H值与土壤可交换态Cd含量呈显著负相关，与铁锰氧化物结合态Cd含量呈显著正相关。马铃薯各器官Cd含量总体表现为根、叶、茎大于果实，且主要以氯化钠提取态和去离子水提取态为主；马铃薯除果实外，根、茎、叶中Cd含量几乎全部超出国家食品安全限值，存在较高的生态风险。土壤 p H值与马铃薯根、茎中Cd含量呈显著负相关；土壤有机质含量与马铃薯叶中Cd含量呈极显著正相关；马铃薯根中Cd含量与茎中Cd含量呈显著正相关。总之，土壤p H值是影响植物吸收Cd的重要因素，其主要通过影响Cd在土壤中的形态分布来影响Cd向马铃薯体内的迁移。控制土壤p H值可有效降低土壤中Cd向植物迁移的能力和农作物中的Cd含量，保障当地农作物食品质量安全。%The content and chemical forms distribution of Cd in farmland soil and roots,stems, leaves and tubers of potato in zinc smelting area in Hezhang county were studied using sequential chemical extraction method.The results showed that,Cd content in farmland soil ranged from 2.53-22.30 mg/kg,Cd mainly existed in the form of exchangeable fraction and Fe-Mn oxides fraction;the soil pH value was significantly negatively correlated with the content of Cd in the form of exchangeable fraction,and significantly positively correlated with the content of Cd in the form of Fe-Mn oxides fraction in soil.The contents of Cd in roots,leaves,stems were higher than that in tubers.NaCl-extractable and H2 O-extractable Cd were dominant in each organ of potato. Except the tubers,Cd contents in roots,stems and leaves of potato exceeded the food safety limits of national standard,had higher ecological risk.The pH value of soil was significantly negatively correlated with the content of Cd in roots and stems of potato,the significant positive correlations were found between organic matter content of soil and the content of Cd in leaves of potato,and between the content of Cd in roots and the content of Cd in stems of potato.Overall,soil pH value was an important factor affecting Cd uptake in plants,which mainly affected the migration of Cd to the potatoes through the influence of chemical forms in the soil.To ensure the quality and safety of local foods,the ability of Cd in soil transfering to plant and the contents of Cd in crops could be reduced through controlling the pH value of soil.
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