Application of biochar prepared from ethanol refinery by-products for Hg stabilization in floodplain soil: Impacts of drying and rewetting

Wang, Alana O.; Ptacek, Carol J.; Paktunc, Dogan; Mack, E Erin; Blowes, David W.

Application of biochar prepared from ethanol refinery by-products for Hg stabilization in floodplain soil: Impacts of drying and rewetting

2020

Wang, Alana O. | Ptacek, Carol J. | Paktunc, Dogan | Mack, E Erin | Blowes, David W.

This study evaluated three biochars derived from bioenergy by-products — manure-based anaerobic digestate (DIG), distillers’ grains (DIS), and a mixture thereof (75G25S) — as amendments to stabilize Hg in contaminated floodplain soil under long-term saturated (up to 200 d) and cyclic drying and rewetting conditions. Greater total Hg (THg) removal (72 to nearly 100%) and limited MeHg production (<65 ng L⁻¹) were observed in digestate-based biochar-amended systems under initial saturated conditions. Drying and rewetting resulted in limited THg release, increased aqueous MeHg, and decreased solid MeHg in digestate-based biochar-amended systems. Changes in Fe and S chemistry as well as microbial communities during drying and rewetting potentially affected MeHg production. Digestate-based biochars may be more effective as amendments to control Hg release and minimize MeHg production in floodplain soils under long-term saturated and drying and rewetting conditions compared to distillers’ grains biochar.

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