Degradation of Crude 4‑MCHM (4-Methylcyclohexanemethanol) in Sediments from Elk River, West Virginia

Isabelle M. Cozzarelli, Denise M. Akob, Mary Jo Baedecker, Tracey Spencer, Jeanne Jaeschke, Darren S. Dunlap, Adam C. Mumford, Amisha T. Poret-Peterson, Douglas B. Chambers

In January 2014, approximately 37,800 L of crude 4-methylcyclohexanemethanol (crude MCHM) spilled into the Elk River, West Virginia. To understand the long-term fate of 4-MCHM, we conducted experiments under environmentally relevant conditions to assess the potential for the 2 primary compounds in crude MCHM (1) to undergo biodegradation and (2) for sediments to serve as a long-term source of 4-MCHM. We developed a solid phase micro-extraction (SPME) method to quantify the cis- and trans- isomers of 4-MCHM. Autoclaved Elk River sediment slurries sorbed 17.5% of the cis-4-MCHM and 31% of trans-4-MCHM from water during the 2-week experiment. Sterilized, impacted, spill-site sediment released minor amounts of cis- and up to 35 µg/L of trans-4-MCHM into water, indicating 4-MCHM was present in sediment collected 10 months post spill. In anoxic microcosms, 300 µg/L the cis- and 150 µg/L trans-4-MCHM degraded to non-detectable levels in 8-13 days in both impacted and background sediments. Under aerobic conditions, 4-MCHM isomers degraded to non-detectable levels within 4 days. Microbial communities at impacted sites differed in composition compared to background samples, but communities from both sites shifted in response to crude MCHM amendments. Our results indicate that 4-MCHM is readily biodegradable under environmentally relevant conditions.