The invention relates to a method for determining the content of bioavailable heavy
metal in a
compost sample, which mainly comprises the following steps that A, different proportions of pure water are added to the
compost sample, supernatant liquids are respectively filtered, and filtrates are collected to obtain a series of filtrates with different quantities of added water; B, a film
diffusion gradient device is respectively put into each filtrate and arranged on a
magnetic stirrer for
adsorption reaction, a binder phase of each film
diffusion gradient device is taken out, a HNO3 solution is added to fully immerse the binder phase, and the concentration of the heavy
metal in the solution is determined after leaching; and C, the concentration of the heavy
metal which is accumulated in the binder phase and the film
diffusion gradient device is calculated. The method has the characteristics of high precision and good
repeatability and stability, and the concentration of the bioavailable heavy metal in the
compost sample can be accurately and quantitatively analyzed in a natural rainfall condition.