A diffusion - precipitation method was developed to determine acid volatile sulfide (AVS) concentrations in freshwater sediments. This method uses silver nitrate as a sulfide trap solution and the concentration of trapped sulfide is determined gravimetrically. The proposed diffusion - precipitation method is more rapid and less expensive than previously developed purge- and - trap methods. Spiked sodium sulfide recoveries using this method $(97~120\%)$ were similar with a previously developed diffusion - absorption method $(93.8~115\%)$ and about $20\%$ greater than a previously developed purge-and-trap method $(74.6~105\%)$. Detection limit of this method $(0.1;{mu}mole;S;g^{-l})$ was comparable with that of diffusion-absorption method $(0.06;{mu}mole;S;g^{-l})$ and purge-and-trap method $(0.05~0.5;{mu}mole;S;g^{-l})$.