Provided herein are methods of treating a composition. In one embodiment, the method includes contacting a sulfur-based bulk reductant with a composition that includes soil and/or water and further includes one or more oxidized organic and/or inorganic compounds. In another embodiment, the method includes contacting a sulfur-based bulk reductant with a composition that includes soil and/or water and further includes one or more chlorinated organic compounds. In still another embodiment, the method includes contacting a sulfur-based bulk reductant with a composition that includes soil and/or water and further includes one or more chemical warfare agents. Also provided herein are sulfur-based bulk reductants for use in remediation of contaminated soil and/or water.