Perchlorate (ClO₄⁻) is globally enriched in Martian regolith at levels commonly toxic to plants. Consequently, perchlorate in Martian regolith presents an obstacle to developing agriculture on Mars. Here, we assess the effect of perchlorate at different concentrations on plant growth and germination, as well as metal release in a simulated Gusev Crater regolith and generic potting soil. The presence of perchlorate was uniformly detrimental to plant growth regardless of growing medium. Plants in potting soil were able to germinate in 1 wt.% perchlorate; however, these plants showed restricted growth and decreased leaf area and biomass. Some plants were able to germinate in regolith simulant without perchlorate; however, they showed reduced growth. In Martian regolith simulant, the presence of perchlorate prevented germination across all plant treatments. Soil column flow-through experiments of perchlorate-containing Martian regolith simulant and potting soil were unable to completely remove perchlorate despite its high solubility. Additionally, perchlorate present in the simulant increased metal/phosphorous release, which may also affect plant growth and biochemistry. Our results support that perchlorate may modify metal availability to such an extent that, even with the successful removal of perchlorate, Martian regolith may continue to be toxic to plant life. Overall, our study demonstrates that the presence of perchlorate in Martian regolith provides a significant challenge in its use as an agricultural substrate and that further steps, such as restricted metal availability and nutrient enrichment, are necessary to make it a viable growing substrate.

In situ building materials and energy resources are necessary for the long‐term human habitation of Mars. Olivine ((Mg,Fe)₂SiO₄) is a regionally abundant mineral on Mars and may potentially serve both purposes. Here we assess olivine hydrolysis (i.e., serpentinization) and related products including magnesite (MgCO₃) as a means to produce a Mg‐based cement and molecular hydrogen (H₂) as an energy resource. Magnesium oxide (MgO) may be derived from Mg(OH)₂ dehydration or calcination (i.e., thermal decomposition) of MgCO₃. In laboratory experiments, Mg‐based concrete using MgO achieved a compressive strength in excess of 20 MPa. Serpentinization‐related H₂ gas concentrations increased with increasing temperature (20 to 50 °C) and decreasing olivine particle size reaching a maximum H₂ production rate of 4.73 μmol g⁻¹ day⁻¹, 3 orders of magnitude greater than previously observed. Results from this study indicate that serpentinization and related products serve as a viable pathway for both concrete and fuel production on Mars with minimal energy expenditure and primarily constrained to the availability of water. Moreover, this process would work equally as well on Earth and has significant potential to decrease global industrial CO₂ emissions.

Plant nutrients such as potassium (K) may be limited in soil systems and additions (i.e., fertilizer) are commonly required. Glaucony is a widely distributed and abundant marine-derived clay mineral present in soils worldwide which may serve as a source of potassium. The South Island of New Zealand contains numerous deposits of glaucony-rich rocks and related soils providing an opportunity to explore how glaucony might be a beneficial source of potassium. Here, the geochemistry of glaucony and its suitability as a mineral source of soil K from four deposits in New Zealand was examined using spatially resolved chemical analyses and dissolution experiments. Geochemical and morphological analyses revealed that glaucony from all deposits were K-enriched and were of the evolved (6%–8% K₂O) to highly evolved type (>8% K₂O). Glaucony derived from growth inside pellets contain elevated K and Fe concentrations compared to bioclast-hosted glaucony. Solubility analysis showed that K was released from glaucony at rates higher than any other metal present in the mineral. Additionally, decreasing the pH and introducing an oxidizing agent (i.e., birnessite which is ubiquitous in soil environments) appeared to accelerate K release. Trace metals including Cr, Zn, Cu, and Ni were present in the solid phase analysis; however, further investigation with a focus on Cr revealed that these elements were released into solution at low concentrations and may present a source of soil micronutrients. These results suggest that glaucony may offer a source of slow releasing K into soils, and so could be used as a locally sourced environmentally sustainable K resource for agriculture, whether in New Zealand or worldwide.

Mineral and rock additions to the environment have been proposed as a pathway to remove atmospheric CO₂. This process occurs when hydrated minerals or rocks increase alkalinity, promoting the formation of bicarbonate. In this study, we evaluate the potential of commonly used hydrated rock and mineral powders to enhance alkalinity and react with both atmospheric and concentrated CO₂. Silicate minerals and rocks exhibit minimal reactivity with atmospheric CO₂ and provide moderate alkalinity enhancement. Volcanic rocks like basalt were shown to release CO₂. Ground cement and Mg(OH)₂, refined from CO₂-free ultramafic rock, significantly increase alkalinity and mineralize both atmospheric and concentrated CO₂. However, the effectiveness of cement waste is limit by its variable CaO content and potential heavy metal contributions. Overall, Mg(OH)₂, derived from silicates, offers a promising pathway for the removal and storage of CO_2.