| Through pot experiment，the influence of nitrogen fertilizer application including NH4HCO3, CO（NH2）2 and Ca（NO3）2 on the availability of arsenic in red soils and arsenic uptake by Brassica chinensis was conducted. The results indicated that the plant biomass was significantly improved due to the application of these three kinds of nitrogen fertilizer at 175 mg N·kg-1, 350 mg N·kg-1 added level with the increased percentage of 104.5%~224.3% compared to control（CK） without N added. Under different N application treatments, the available arsenic in soils and plant accumulation of arsenic all increased significantly at P＜0.05 significant level. Under different N application treatments, the available amount of arsenic in soils was 30.5~49.4 times more than that of control, and the highest amount appeared in the 350 mg N·kg-1 Ca（NO3）2 treatment, and the least amount occurred for the 350 mg·kg-1 NH4HCO3 treatment. The uptake amount through the harvest crop was 0.75~4.32 times that of control. And the relatively high amount appeared in 175 mg N·kg-1 NH4HCO3 and 350 mg N·kg-1 Ca（NO3）2 treatments. The least arsenic concentration in plant and arsenic amount obtained from the harvested crop occurred for 350 mg N·kg-1 CO（NH2）2 treatment and 175 mg N·kg-1 Ca（NO3）2 treatment. With the application of these three kinds of nitrogen fertilizer, transformation from residual fraction into other four fractions like soluble arsenic and corresponding release of arsenic from soils was observed from this study, indicating the arsenic uptake amount by crops and environmental risk increased. |
