Arsenic-Imposed Effects on Schwertmannite and Jarosite Formation in Acid Mine Drainage and Coupled Impacts on Arsenic Mobility

Abstract

This study explores interactions between As and Fe­(III) minerals, predominantly schwertmannite and jarosite, in acid mine drainage (AMD) via observations at a former mine site combined with mineral formation and transformation experiments. Our objectives were to examine the effect of As on Fe­(III) mineralogy in strongly acidic AMD while also considering associated controls on As mobility. AMD at the former mine site was strongly acidic (pH 2.4 to 2.8), with total aqueous Fe and As decreasing down the flow-path from ∼400 to ∼20 mg L–1 and ∼33,000 to ∼150 μg L–1, respectively. This trend was interrupted by a sharp rise in aqueous As­(III) and Fe­(II) caused by reductive dissolution of As-bearing Fe­(III) phases in a sediment retention pond. Attenuation of Fe and As mobility occurred via formation of As­(V)-rich schwertmannite, As­(V)-rich jarosite, and amorphous ferric arsenate (AFA), resulting in solid-phase As concentrations spanning ∼13 to ∼208 g kg–1. Schwertmannite and jarosite retained As­(V) predominantly by structural incorporation involving AsO4-for-SO4 substitution at up to ∼40 and ∼22 mol %, respectively. Arsenic strongly influenced Fe­(III) mineral formation, with high As­(V) concentrations causing formation of AFA over schwertmannite. Arsenic also strongly influenced Fe­(III) mineral evolution over time. In particular, increasing levels of As­(V) incorporation within schwertmannite were shown, for the first time, to enhance the transformation of schwertmannite to jarosite. This significant discovery necessitates a re-evaluation of the prevailing paradigm that As­(V) retards schwertmannite transformation.

Glycerol amendment enhances biosulfidogenesis in acid mine drainage-affected areas: An incubation column experiment

“…The Fe/S elemental relation and characteristic pincushion shape was coherent with early iron oxyhydroxysulfate schwertmannite (Fe 8 O 8 SO 4 (OH) 6 * nH 2 O) precipitate, which occasionally fossilized the preexisting microorganisms ( Figures 7A,B,E ). These particles showed incorporation of As, which is a common feature of this mineral ( Regenspurg and Peiffer, 2004 ; Burton et al, 2009 ; Burton et al, 2021 ). A higher Fe/S ratio and spherical, globular or idiomorphic crystals, with or without K, identified other iron particles as Fe hydroxysulfate jarosite (K/H 3 O + Fe 3 (SO 4 ) 2 (OH) 6 ; Figures 7B–D,F ).…”

“…It is widely reported that during the dissolution and recrystallization of schwertmannite, this mineral releases ionic species initially adsorbed onto the surface or in its’ structure ( Jones et al, 2006 ; Schoepfer and Burton, 2021 ; Zhang et al, 2022 ). On the one hand, the release of P ( Figure 5A ) to the interstitial space might be beneficial for the microbial growth in oligotrophic systems, but the release of As and Cd, commonly adsorbed onto schwertmannite and jarosite ( Burton et al, 2009 ; Burton et al, 2021 ), would be hazardous to the local ecosystem. From the biotechnological point of view, it is therefore crucial to balance the re-solubilization processes with SRB-mediated sulfide precipitation.…”

Removal and Potential Recovery of Dissolved Metals from Acid Sulfate Soil Drainage by Spent Coffee-Grounds and Dissolved Organic Carbon

“…These iron sulfate species in Mediterranean (Fitzpatrick et al 2017), tropical (Johnston et al 2010;Keene et al 2011;Johnston et al 2016), and subtropical (Ahern et al 2004;Claff et al 2010) regions have caused severe vegetation degradation by forming schwertmannite and/or akaganeite, two poorly crystalline Secondary Fe(III) phases (Shahabi-Ghahfarokhi et al 2022). Therefore, by using SCGs and HA, the formation of these problematic secondary iron species are potentially restricted by limiting the Fe and sulfate to form schwertmannite/akaganeite, often seen in sulfuric rich, acidic settings (Burton et al 2021;Shahabi-Ghahfarokhi et al 2022). However, the effects of simultaneous addition of SCGs and DHA should be further studied.…”

Investigation of the Interactions Occurring Between Cr(VI) and Citric Acid-Schwertmannite Composites: A Macroscopic and In Situ ATR-FTIR Study

“…Schwertmannite (Fe 16 O 16 (OH) 12 (SO 4 ) 2 ), a typical metastable secondary iron-hydroxysulfate mineral, is widespread in acidic sulfate environments such as acid mine drainage (AMD) or acid sulfate soils. − Schwertmannite plays an important role in immobilizing toxic metals due to its large specific surface area as well as abundant hydroxyl functional groups and structural sulfate for ligand exchange, − which exhibits a specific adsorption mechanism compared to other common iron oxides, such as ferrihydrite and goethite . For example, Cr­(VI) is widely detected in AMD-polluted environments and could directly substitute sulfate through ligand–exchange reactions because these two anions possess the same charge and similar ionic radius .…”