Abstract: This study was conducted to explore the single and interactive effects of arsenic (As) and antimony (Sb) on the accumulation and transformation of As and Sb in Boston fern (Nephrolepis exaltata L.) at tissue and sub-cellular levels.  The results indicated that both single and co-treatment of As and Sb decreased the biomass of Boston fern, while increased the concentrations of As and Sb in the fern plant, as compared with the control. Arsenic and Sb concentrations in fern tissues were in the order of roots > leafstalks > leaflets and roots > leaflets > leafstalks, respectively. The As or Sb concentrations in various tissues of Boston fern under co-treatments were lower than those under single treatments, suggesting the existence of antagonism between As and Sb in Boston fern. Subcellular distributions of both elements were also determined. Under co-treatments, As in roots could be impelled from cell wall to cytosol and organelle, while in both leaflets and leafstalks it was from cytosol to cell wall and organelle. Meanwhile, Sb in roots could be stimulated from organelle to cytosol and cell wall, while in leaflets and leafstalks it was from cell wall to cytosol and organelle. When only As(III) was added, As(V) dominated in the roots and DMA prevailed in the leaflets, while the co-addition of Sb(III) promoted more As(III) to be transformed to As(V) and DMA. When only Sb(III) was added, Sb(III) predominated in various tissues of Boston fern, while co-addition of As(III) intensively inhibited the transformation of Sb(III) in the roots and leafstalks, whereas in the leaflets As(III) promoted the transformation of Sb(III) to Sb(V).

Key words: genetically modified crops, soil animals, Bt protein, ecological risk assessment