Variability of ¹³⁷Cs inventory at a reference site in west-central Iran

¹³⁷Cs technique has been widely used for the evaluation rates and patterns of soil erosion and deposition. This technique requires an accurate estimate of the values of ¹³⁷Cs inventory at the reference site. This study was conducted to evaluate the variability of the inventory of ¹³⁷Cs regarding to the sampling program including sample size, distance and sampling method at a reference site located in vicinity of Fereydan district in Isfahan province, west-central Iran. Two 3 × 8 grids were established comprising large grid (35 m length and 8 m width), and small grid (24 m length and 6 m width). At each grid intersection two soil samples were collected from 0 to 15 cm and 15-30 cm depths, totally 96 soil samples from 48 sampling points. Coefficients of variation for ¹³⁷Cs inventory in the soil samples was relatively low (CV = 15%), and the sampling distance and methods used did not significantly affect the ¹³⁷Cs inventories across the studied reference site. To obtain a satisfactory estimate of the mean ¹³⁷Cs activity in the reference sites, particularly those located in the semiarid regions, it is recommended to collect at least four samples along in a grid pattern 3 m apart.