Mining Contamination, Distribution, and Dispersal of Fluvial Sediments in Rush Creek, Buffalo National River, Arkansas

Keywords: mining contamination, fluvial geomorphology, Ozark rivers, river geochemistry, protected lands
Abstract Type: Poster Abstract

Abstract

The Rush Mining District (RMD) was active from the late 1890s through the late 1930s with sporadic operations continuing until the early 1960s, producing approximately 35% of the Zn ore in Northern Arkansas. Since 1972, the RMD and the lower three kilometers of Rush Creek have been protected by the U.S. National Park Service as a cultural resource. This protection includes all remnant mine workings and mining waste piles, preserving a long-term mining influence on Rush Creek. Therefore, we investigated elemental concentrations in lower Rush Creek surficial sediment deposits to understand the distribution of Zn across space and fluvial landforms. We sampled channel beds, bars, benches, floodplains, and terraces from six 120-meter reaches and a larger downstream sediment accumulation zone near the mouth of Rush Creek. We observed interesting longitudinal and landform concentration patterns, which we will analyze and describe. Initial results suggest an increasing trend for Zn levels downstream of RMD mines, generally higher Zn concentrations near the mouth of Rush Creek, and concentration differences among fluvial landforms. Median Zn concentrations and reach-scale data suggest an inverse relationship between Zn concentrations and fluvial landform elevation, and elemental ratios of Zn, Ca, and Fe also support mining wastes as a source material for elevated Zn levels. Additionally, many samples exceeded local background concentrations and the Sediment Quality Standard TEC (Threshold Effect Concentration) for Zn, hinting at potential health challenges for aquatic organisms.