New Mexico Geological Society · Socorro, NM

(575) 835-5410

Raphael Rivadavia1, Noah Jemison2, Lurima Faria3, Marc Friedman4, Abdul-Mehdi Ali5, Angelica Saenz-Trevizo5, Eric Peterson5, Geisianny Moreira6, Katelin Fisher7, Geoffrey Williams8, Johanna Blake9, Adrian Brearley5, Debora Rodrigues3, Gregory Bonito4 and Jose Cerrato1

1Gerald May Department of Civil Engineering, MSC01 1070 1 University of New Mexico, Albuquerque, NM, 87131, United States of America, riva92@unm.edu
2Center for MicroEngineered Materials, MSC04 2790 University of New Mexico, 1001 University Blvd. SE Suite 103, Albuquerque, NM, 87106, United States of America
3Clemson University – Environmental Engineering and Earth Science Department, 445A Brackett Hall, Clemson, SC, 29634-0919, United States of America
4Michigan State University – Department of Plant, Soil, and Microbial Science, 1066 Bogue Street, East Lansing, MI, 48824, United States of America
5The University of New Mexico – Department of Earth and Planetary Sciences, Northrop Hall, 221 Yale Blvd NE, Albuquerque, NM, 87131, United States of America
6The University of New Mexico College of Pharmacy – Department of Pharmaceutical Sciences, MSC03 2040, 1 University of New Mexico, Albuquerque, NM, 87131-0001, United States of America
7The University of New Mexico – Center for Water and the Environment, MSC01 1070, 1 University of New Mexico, Albuquerque, NM, 87131, United States of America
8Michigan State University – Department of Forestry, 480 Wilson Road, Room 126, East Lansing, MI, 48824-6402, United States of America
9U.S. Geological Survey, 6700 Edith Blvd. NE, Albuquerque, NM, 87113

This study investigated the effects of redox conditions on the mobilization of Pb, Cu, and Fe from sediments of an acid mine drainage (AMD)-impacted stream. Controlled laboratory microcosm experiments were conducted, integrating electron microscopy and aqueous chemistry. Microcosms containing synthetic river water (SRW) and sediments were amended with acetate and cycled through oxic-anoxic-oxic phases, each lasting 5 days (total of 15 days). STEM-EDXS analysis of the sediments revealed Pb and Cu associated with Al-silicates and jarosite. High-throughput DNA sequencing of the fungal community identified metal-tolerant genera in the sediments, including Aspergillus, Trichoderma, and Fusarium. In the microcosm experiments, Fe release was minimal during the initial oxic phase (<3 mg L⁻¹), peaked under anoxia (~250 mg L⁻¹ without acetate), and decreased in the final oxic phase (<70 mg L⁻¹). Notably, Pb concentrations consistently surpassed EPA action levels (15 µg L⁻¹), independent of redox and carbon amendment conditions. Extraction assays confirmed high water lability of Pb and Cu from sediments at an acidic pH (3.4) (Pb: 27 µg L⁻¹, Cu: 75 µg L⁻¹), with significantly lower lability at circumneutral pH (6.4) (Pb: 7 µg L⁻¹, Cu: 3 µg L⁻¹). The results highlight that Pb and Cu are easily labile under the natural acidic conditions of AMD-impacted streams, posing a risk to ecosystems and human health. Further studies are necessary to investigate the role of fungi in the biogeochemical processes affecting metal mobilization in this environment.

2025 New Mexico Geological Society Annual Spring Meeting April 25, 2025, Macey Center, Socorro, NM Online ISSN: 2834-5800

Pages: 105