CV-AFS Determination of Various Species of Mercury in Paddy Field Soil

A method of 5-step successive extraction for separation of various species of mercury ［including: (a) soluble and changeable species; (b) Mn, Fe oxide combined species; (c) combined organic species; (d) HNO3-soluble species and (e) residual species］ in paddy field soil was proposed, and contents of the 5 species as well as the content of total mercury were determined by CV-AFS. Linear relationship between values of fluorescence intensity and mass concentration of mercury was found in the range within 32.0 μg·L-1, with detection limit (3s) of 0.022 9 μg·L-1. Precision of the method was tested giving value of RSD (n=10) of 1.1%. Recovery was also made by standard addition method, using 4 soil samples as matrixes, give results in the range of 89.0%-94.0%. As shown by the analytical results of the paddy field soil samples, the contents of the 5 species of mercury were decreased in samples with increase of depth of soil-sampling in vertical directions; and the magnitude of contents of the 5 species of mercury in samples sampled in the horizontal directions were found to decrease in the following order: species(c)>(d)>(e)>(b)>(a).