Bacterial Productivity in a Ferrocyanide-Contaminated Aquifer at a Nuclear Waste Site

Abstract

This study examined potential microbial impacts of cyanide contamination in an aquifer affected by ferrocyanide disposal from nuclear waste processing at the US Department of Energy’s Hanford Site in south-eastern Washington State (USA). We examined bacterial productivity and microbial cell density in groundwater (GW) from wells with varying levels of recent and historical total cyanide concentrations. We used tritiated leucine (3H-Leu) uptake as a proxy for heterotrophic, aerobic bacterial productivity in the GW, and we measured cell density via nucleic acid staining followed by epifluorescence microscopy. Bacterial productivity varied widely, both among wells that had high historical and recent total cyanide (CN−) concentrations and among wells that had low total CN− values. Standing microbial biomass varied less, and was generally greater than that observed in a similar study of uranium-contaminated hyporheic-zone groundwater at the Hanford Site. Our results showed no correlation between 3H-Leu uptake and recent or historical cyanide concentrations in the wells, consistent with what is known about cyanide toxicity with respect to iron speciation. However, additional sampling of the CN− affected groundwater, both in space and time, would be needed to confirm that the CN− contamination is not affecting the GW biota.

Groundwater Contamination, Subsurface Processes, and Remediation Methods: Overview of the Special Issue of Water on Groundwater Contamination and Remediation

“…Under the heading of natural sources, Vera et al [5] focus on arsenate, and Haluska et al [6] address sulfate-whose source can be natural or anthropogenic. Most of the studies considered anthropogenic sources, with Beretta et al [7] and Haluska et al [6] addressing the industrial additive and known carcinogen hexavalent chromium, Plymale et al [8] focusing on the toxic salt ferrocyanide, Haluska et al [6] measuring the organic contaminants 1,4-dioxane and hexahydro-1,3,5-trinitro-s-triazine (RDX), Prieto-Amparán et al [9] studying sewage effluent, and Wells et al [10] tracking the fertilizer-derived anion nitrate. As a particular subset of anthropogenic contaminants, two studies discuss emerging contaminants, particularly related to hydrocarbon resources, as Hu et al [11] study oil shale development, while Ning et al [12] focus on petroleum contamination.…”

“…In parallel, Hu et al [11] discuss the potential impacts from emerging contaminants related to oil shale development. Three studies explore the central role of biology in groundwater remediation, reflecting our new understanding of subsurface processes through the interdisciplinary lens of biogeochemistry: Ning et al [12] study the spatial pattern of bacterial communities at a petroleum-contaminated site; Plymale et al [8] study bacterial communities at a nuclear waste-contaminated site; and Moradi et al [14] contribute a model describing thermally-enhanced bioremediation. Taken together, these studies demonstrate that our ability to remediate groundwater depends on knowing the contaminants, understanding the fluid mechanics, and interpreting processes in the context of hydrology, geochemistry, and microbiology.…”

Treatment of gold ore cyanidation wastewater by adsorption onto a Hydrotalcite-type anionic clay as a novel adsorbent

“…Hence, EPA has set an enforceable regulation for cyanide at 0.2 mg/ L. Large volumes of wastewaters annually produced by various industrial activities such as mining (extraction of gold, silver, etc. ), electroplating, and production of synthetic fibers, plastics, organic chemicals and pharmaceuticals [1][2][3]. They usually contain high concentrations of free and metalcomplexed cyanide species and must be treated before they are released into the environment [4,5].…”

Chemical Characteristics of Electron Shuttles Affect Extracellular Electron Transfer: Shewanella decolorationis NTOU1 Simultaneously Exploiting Acetate and Mediators

“…These have been used as an effective electron shuttle in the MFC study (Choi et al, 2003; Miroliaei et al, 2015). The humic substances (typically studied using anthraquinone-2,6-disulfonate (AQDS) as a model substitution, Newman and Kolter, 2000) and ferrocyanide (formed in a nuclear-waste-processing site, Plymale et al, 2018) possess redox capabilities and exist in the ground water. Therefore, regarding scaling-up BES for practical applications, it is of utmost importance—essential, in fact—to know just how these external mediators affect EET.…”