A GEOCHEMICAL AND MICROBIOLOGICAL ANALYSIS OF THREE ABANDONED MINE DRAINAGES IN THE MIDDLE ANTHRACITE BELT IN NORTHUMBERLAND COUNTY, PA

In 2020 we began a project characterizing chemistry and microbes at abandoned mine drainage (AMD) sites in the Middle Anthracite Belt in eastern Pennsylvania. The three AMD sites we sampled drain different mine pools, each with unique chemical characteristics and microbial assemblages. Discharge sites were Big Mine Run (BMR) near Ashland, PA (fed from the Centralia pool); Sterling Discharge (SD) near Shamokin, PA, fed from the Henry Clay-Sterling pool; and the inflow to the Scarlift Site 15 AMD treatment system (SL) near Ranshaw, PA, sourced from the Corbin Mine Pool. Dissolved oxygen (DO), pH, and conductivity were measured in situ, then samples collected and returned to the lab for analysis. Alkalinity and acidity were analyzed within 4 hours. Subsamples were preserved for later analysis of 11 selected metals, 7 simple cations, and 8 anions. Each discharge was geochemically unique in terms of pH (4.38, 6.12 and 4.46 for BMR, SD, and SL), DO (10.08, 1.72, and 2.52 mg/L for BMR, SD, and SL), and conductivity (843, 659, and 560 µS/cm for BMR, SD, and SL). Iron concentrations were relatively low at BMR (3.6 ppm compared with 16.7 and 13.6 ppm for SL and SD), but BMR had the highest concentrations of Al (4.4 ppm, compared with 3.8 ppm for SL and <0.5 ppm for SD) and Mn (5.3 ppm, compared with 2.7 and 2.1 ppm for SL and SD). Alkalinity was detected at SD (61 mg/L as CaCO₃) but not at the other sites. Yellow boy (orange deposits on the rocks and bottom) was collected at all sites and genetic material isolated and sent to GeneWiz for taxonomic analysis. Each of the sites had a distinct collection of Operational Taxonomic Units (OTUs), with many OTUs in common but in very different relative abundances. Half or more of the OTUs were unclassified; of the genera identified, many have been demonstrated to be important in iron and sulfur biogeochemical cycles. SL was dominated by Gallionella, followed by Sulfurimonas and Sulfuicurvum. BMR was also dominated by Gallionella to a lesser extent, with Hyphomicrobium and Bradyrhizobium next highest in abundance. SD was dominated by Gallionella, followed by Geobacter and Rhodoferax. Presence of Gallionella at SD and SL was surprising, as it is known mostly from near neutral pH environments, having only recently being reported in a low pH environment.