土壤砷、铅和汞胁迫对纽荷尔脐橙不同器官中砷铅汞质量分数的影响

Study on the concentrations of As,Pb and Hg heavy metals in organs and tissues of Newhall navel orange trees under soil stress of As,Pb and Hg

枳砧纽荷尔脐橙(Citrus sinensis Osbeck.)盆栽苗,在碱性紫色石骨子土中单独或混合加入砷、铅、汞,以研究砷、铅、汞在植株器官组织中的分布与累积。在3 a的盆栽试验期间,土壤中的砷、铅、汞质量分数分别维持在添加质量分数的30%～86%、46%～64%和84%～118%。结果表明,不同重金属在植株不同器官部位质量分数不一样,砷和汞在植株器官组织中的质量分数表现相同特征,根系>叶片>枝干>果皮>果肉,而铅为:根系>枝干>叶片>果皮>果肉。高质量分数处理的根系中砷、铅和汞质量分数最高分别达到7.2、773.6、0.50 mg.kg-1,而砷、铅和汞在果皮中最高质量分数仅分别为0.15、0.06、0.006 mg.kg-1,果肉中最高质量分数分别为0.06、0.05、0.004 mg.kg-1,砷、铅、汞在果实中的最高质量分数远低于国家绿色食品限值标准。未发现土壤砷+铅+汞混合处理对其在植株器官组织内的累积有任何拮抗或协同效应。

Pot culture experiment was carried out to study heavy metal （HM）uptake from the soil contaminated with As, Pb and Hg and HM accumulation in organs and tissues of the plant. Calcareous purple soil was employed for pot culture by young Newhall navel orange （Citrus sinensis O sb. ） on trifoliate orange （Poncirus trifoliate Raf. ） rootstock In the beginning, different HM was applied into the soil and made the additional HM concentrations in the soil as follows： As （30,60 and 120 mg·kg^-1）, Pb （500,1 000 and 2 000 mg·kg^-1） ,Hg （1.0, 2.0 and 4.0 mg·kg^-1） ,As＋ Pb ＋ Hg （40 mg·kg^-1As＋500 mg·kg^-1Pb＋1.5 mg·kg^-1, and 80 mg·kg^-1 As ＋ 1 000 mg·kg^-1 Pb＋3.0 mg·kg^-1 Hg） .The potted soil of the control was not applied any additional HM,but it had natural base concentrations of As,Pb and Hg about 7.10,24.19 and 0.16 mg·kg^-1,respectively. In spring 2004, one-year-old Newhall navel orange trees were planted in pots. During 3-year pot culture, the concentrations of As, Pb and Hg in potted soils were stably kept at about 30% to 86%, 46% to 64%, and 84% to 118% of their original additional concentrations, respectively. Results showed that 2 years after potted culture, the accumulated concentration of As and Hg in organs and tissues of plant had the same characteristics： roots〉 leaves 〉 sticks 〉peel〉pulp,and that of Pb was roots〉sticks〉 leaves〉peel〉pulp. For the highest-stress groups, the highest As, Pb and Hg concentrations accumulated in roots were 7.2, 773.6 and 0.50 mg·kg^-1, respectively. However, the HM concentration accumulated in fruit peel and pulp was low. The highest As, Pb and Hg concentrations in fruit peel were only 0.15, 0.06 and 0.006 mg·kg^-1,respectively; and that in fruit pulp were only 0.06,0.05 and 0.004 mg·kg^-1 ,respectively. The highest HM concentrations in orange fruit in this experiment were much lower than the maximum residue limits of China National Green Food Standard. As＋ Pb＋Hg treatment did not show antagonistic or synergistic effects on heavy metal accumulation in plant organs or tissues.