The use of chemical and instrumental methods in the study of the forms of occurrence of sulfides in bottom sedimentsYury A. Fedorov, Dmitry N. Garkusha, Leonid Yu. Dmitrik, Boris V. Talpa and Anna V. MikhailenkoE3S Web Conf., 265 (2021) 02013DOI: https://doi.org/10.1051/e3sconf/202126502013