成都东郊稻田水中砷形态的测定及分布特征

采用氢化物发生-原子荧光光谱法测定了成都东郊4块稻田水中砷的形态.研究发现,该区域稻田表面水砷浓度平均值为3.15—7.9μg.L-1,土壤孔隙水为18.71—53.71μg.L-1,除4号稻田土壤孔隙水外,其余各稻田表面水及土壤孔隙水中砷浓度的平均值均未超出国家农田灌溉水质标准.垂直方向上,土壤孔隙水中各形态砷的浓度均比稻田表面水中的高,且都在水-土界面或接近界面处最大,然后依次向下呈递减趋势.水平方向上,各形态砷的浓度因所处稻田条件的不同而分布各异.各形态砷在所研究稻田水中的分布皆呈现出可溶态砷>颗粒态砷、三价砷>五价砷的特征.

Determination and distribution of arsenic species in the water of rice paddy in the east suburb of Chendu

The method of hydride generation-atomic fluorescence spectrometry was used for the determination of arsenic species in the water of rice paddy in the east suburb of Chengdu.It was found that the average concentration of total arsenic was in the range of 3.15—7.90 μg · L-1 in the surface water and 18.71—53.71 μg · L-1 in the porewater,respectively,most of which is lower than the Standard of National Agricultural Irrigation Water.In the vertical direction,the concentration of arsenic species in porewater was found to be higher than that in surface water,and the concentrations of all arsenic species were found to be the highest at the water-soil interface or near the interface.They had a decreasing tendency with increasing depth.In the horizontal direction,the distribution of arsenic species was different due to different rice paddy conditions.The average concentration of all arsenic species in the studied rice paddy waters follows the order of dissolved arsenic > particulate arsenic,As(Ⅲ)> As(Ⅴ).