Micrometric pyrite catalyzes abiotic sulfidogenesis from elemental sulfur and hydrogen.

Hydrogen sulfide (HS) in environments with temperatures below 100 °C is generally assumed to be of microbial origin, while abiotic HS production is typically restricted to higher temperatures (T). In this study, we report an abiotic process for sulfidogenesis through the reduction of elemental sulfur (S) by hydrogen (H), mediated by pyrite (FeS). The process was investigated in detail at pH 4 and 80 °C, but experimental conditions ranged between 40 and 80 °C and pH 4-6.

Biosulfidogenesis Mediates Natural Attenuation in Acidic Mine Pit Lakes.

Acidic pit lakes are abandoned open pit mines filled with acid mine drainage (AMD)-highly acidic, metalliferous waters that pose a severe threat to the environment and are rarely properly remediated. Here, we investigated two meromictic, oligotrophic acidic mine pit lakes in the Iberian Pyrite Belt (IPB), Filón Centro (Tharsis) (FC) and La Zarza (LZ). We observed a natural attenuation of acidity and toxic metal concentrations towards the lake bottom, which was more pronounced in FC.

Quantifying, assessing and removing the extreme gas load from meromictic Guadiana pit lake, Southwest Spain.

High gas charges in deep waters of lakes can represent a hazard to the lives of human beings and animals in the surrounding. As this danger was feared, we quantified the amount of dissolved gas in Guadiana pit lake (Las Herrerías, Huelva; southwest Spain) and documented the temporal evolution over a period of two years. Gas pressure due to dissolved gases, such as carbon dioxide, methane and nitrogen was measured.

Extreme carbon dioxide concentrations in acidic pit lakes provoked by water/rock interaction.

We quantify the gas pressure and concentration of a gas-charged acidic pit lake in SW Spain. We measured total dissolved gas pressure, carbon dioxide (CO2) concentration, major ion concentration, isotopic composition of dissolved inorganic carbon (δ(13)C(DIC)), and other physicochemical parameters. CO2 is the dominant dissolved gas in this lake and results mainly from carbonate dissolution during the interaction of acidic water with wall rocks, followed by diffusive and advective transport through the water column.