Aeroponic Technology for Accelerated Weathering of Extraterrestrial Regolith to Extract Plant Essential Nutrients and Generate Arable Soils.

Advancements in off-world food and fiber production should seek to utilize regolith as a source of nutrients and prepare it for use as a solid plant growth substrate. Towards this goal, aeroponic biowaste streams containing both inorganic nutrients and root system efflux from plants provide an opportunity for accelerated weathering and enhancement of extraterrestrial soils. To test this hypothesis, an aeroponic system was built that contained Martian simulant (Mars Mojave Simulant-2; MMS-2), inert sand, and a no-filter control to evaluate the in-line filters for simultaneous mineral weathering and recycling of biowastes from wheat.

Silicate coprecipitation reduces green rust crystal size and limits dissolution-precipitation during air oxidation.

Green rusts (GR) are mixed-valence iron (Fe) hydroxides which form in reducing redox environments like riparian and wetland soils and shallow groundwater. In these environments, silicon (Si) can influence Fe oxides' chemical and physical properties but its role in GR formation and subsequent oxidative transformation have not been studied starting at initial nucleation. Green rust sulfate [GR(SO)] and green rust carbonate [GR(CO)] were both coprecipitated from salts by base titration in increasing % mol Si (0, 1, 10, and 50).

Sea-level rise and arsenic-rich soils: A toxic relationship.

In the United States, dangerously high arsenic (As) levels have been found in drinking water wells in more than 25 states, potentially exposing 2.1 million people to drinking water high in As; a known carcinogen. The anticipated sea-level rise (SLR) is expected to alter soil biogeochemical and hydrological conditions, potentially impacting their ability to sequester As.

Saltwater intrusion increases phosphorus abundance and alters availability in coastal soils with implications for future sea level rise.

Sea level rise (SLR) promotes saltwater intrusion (SWI) into coastal soils globally at an increasing rate, impacting phosphorus (P) dynamics and adjacent water quality. However, how SWI influences P molecular speciation and availability in coastal soils remains poorly understood. By using a space-for-time substitution strategy, we evaluated the SWI impacts on P transformation along a SWI gradient at the Rehoboth Inland Bay, which consists of five sampling locations along a transect representing different SWI degrees.

Carbon Fate, Iron Dissolution, and Molecular Characterization of Dissolved Organic Matter in Thawed Yedoma Permafrost under Varying Redox Conditions.

Permafrost soils store ∼50% of terrestrial C, with Yedoma permafrost containing ∼25% of the total C. Permafrost is undergoing degradation due to thawing, with potentially hazardous effects on landscape stability and water resources. Complicating ongoing efforts to project the ultimate fate of deep permafrost C is the poorly constrained role of the redox environment, Fe-minerals, and its redox-active phases, which may modulate organic C-abundance, composition, and reactivity through complexation and catalytic processes.

Zinc speciation in highly weathered tropical soils affected by large scale vegetable production.

Agriculture in highly weathered tropical soils often requires considerable application of lime and fertilizers to ensure satisfactory plant nutrient levels. The consequences of these continue long-term applications is not well understood may induce changes in soil chemical properties, the abundance, and speciation of potentially toxic trace element and as well as of micronutrients in agriculture soils. In this study, we evaluated the adsorption (at pH 5) and speciation of Zn in tropical soils (both agricultural and native vegetation) as a function of fertilization and contact time using chemical fractionation analyses and X-ray absorption spectroscopy.

A multi-scale assessment of the impact of salinity on the desorption of chromate from hematite: Sea level rise implications.

The solubility and transport of Cr(VI) is primarily controlled by adsorption-desorption reactions at the surfaces of soil minerals such as iron oxides. Environmental properties such as pH, ionic strength, and ion competition are expected to affect the mobility and fate of Cr(VI). Sea level rise (SLR), and consequent seawater intrusion, is creating a new biogeochemical soil environment at coastal margins, potentially impacting Cr(VI) retention at contaminated sites.

Chromium speciation and mobility in contaminated coastal urban soils affected by water salinity and redox conditions.

Chromium (Cr) is a redox-sensitive element in contaminated coastal urban soils. Sea level rise (SLR) with subsequent soil inundation may facilitate Cr transformation and mobilization through alterations in local redox conditions and porewater ion composition. We investigated the impact of water salinity and redox conditions on Cr chemistry in these environments.

Influence of clay mineral weathering on green rust formation at iron-reducing conditions.

Green rusts (GR) are important drivers for trace metal and nutrient cycling in suboxic environments. We investigated whether green rusts would incorporate aluminum (Al) or other elements from naturally-formed clay minerals containing easily-weatherable clay minerals (e.g.

The adsorption of arsenate and p-arsanilic acid onto ferrihydrite and subsequent desorption by sulfate and artificial seawater: Future implications of sea level rise.

Sea level rise (SLR) is estimated to impact 25% of the world's population along coastal areas leading to an increase in saltwater intrusion. Consequently, changes in the soil biogeochemistry of currently non-saline and/or well-drained soils due to saltwater intrusion are of major concern. Saltwater intrusion is expected to affect farmland across large broiler producer regions, where large amounts of manure containing organic arsenicals were applied over the past decades.

Hydrologic Control on Arsenic Cycling at the Groundwater-Surface Water Interface of a Tidal Channel.

Historical industrial activities have resulted in soil contamination at sites globally. Many of these sites are located along coastlines, making them vulnerable to hydrologic and biogeochemical alterations due to climate change and sea-level rise. However, the impact of hydrologic dynamics on contaminant mobility in tidal environments has not been well studied.

Coupling Molecular-Scale Spectroscopy with Stable Isotope Analyses to Investigate the Effect of Si on the Mechanisms of Zn-Al LDH Formation on Al Oxide.

While silicate has been known to affect metal sorption on mineral surfaces, the mechanisms remain poorly understood. We investigated the effects of silicate on Zn sorption onto Al oxide at pH 7.5 and elucidated the mechanisms using a combination of X-ray absorption fine structure (XAFS) spectroscopy, Zn stable isotope analysis, and scanning transmission electron microscopy (STEM).

Sea-level-rise-induced flooding drives arsenic release from coastal sediments.

Sea-level rise (SLR) has a vital influence on coastal hydrogeological systems, biogeochemical processes, and the fate of coastal contaminants. However, the effects of SLR-induced perturbations on the mobilization of coastal pollutants are not fully understood. In this study, the impact of SLR-induced flooding on the concentration and speciation of arsenic and selected hazardous chemicals is investigated using exceedingly contaminated sediments (5-6% As) collected from an urban coastal site in Wilmington, DE, USA.

Combining zinc desorption with EXAFS speciation analysis to understand Zn mobility in mining and smelting affected soils in Minas Gerais, Brazil.

Zinc contents exceeding regulatory levels have been documented in several areas in Brazil and elsewhere, especially in sites surrounding mining and smelting sites. Studies involving Zn release and speciation are keys to assess the mobility and bioavailability and thus the potential ecological risk of this element. This study evaluated Zn desorption and speciation from soils affected by mining (soils from a mine area, classified as Technosols) and smelting (mine tailing) activities in Brazil with high total Zn contents, ranging from 1.

Cadmium speciation and release kinetics in a paddy soil as affected by soil amendments and flooding-draining cycle.

Cadmium bioavailability in paddy soils is strongly affected by flooding-draining cycle. In this study, we used synchrotron-based X-ray absorption spectroscopy and a stirred-flow method to investigate the effects of flooding-draining and amendments of CaCO and CaSO on Cd speciation and release kinetics from a Cd-spiked paddy soil (total Cd concentration of 165 mg kg). Extended X-ray absorption fine structure analysis showed that Cd was predominantly bound to non-iron-clay minerals (e.

Elucidation of soil phosphorus speciation in mid-Atlantic soils using synchrotron-based microspectroscopic techniques.

Phosphorus deficiency and excess are concomitant problems in agricultural soils of the mid-Atlantic region. A fundamental understanding of soil P speciation is essential to assess P fate and transport in these soils. Current methods for soil P speciation often rely on sequential chemical extractions, which can introduce artifacts during analysis.

Mechanistic insights into iodine enrichment in groundwater during the transformation of iron minerals in aquifer sediments.

Long-term intake of groundwater with elevated iodine concentration can cause thyroid dysfunction in humans; however, little is known on the mechanisms controlling the fate of iodine in groundwater systems. In this study, the groundwater and aquifer sediment samples from the Datong basin, a geologic iodine-affected area, were collected to perform the batch incubation experiments to understand the release and enrichment of iodine in groundwater systems. The results showed that the groundwater from the deep confined aquifer had a total iodine concentration of 473 μg/L, higher than that of shallow groundwater, and iodide is the dominant species of iodine.

Iron Speciation in Organic Matter Fractions Isolated from Soils Amended with Biochar and Organic Fertilizers.

The role and distribution of iron (Fe) species in physical soil fractions have received remarkably little attention in field-scale systems. Here, we identify and quantify the Fe phases into two fractions (fine sand, FSa, and fine silt and clay, FSi + Cl), isolated from an agricultural soil unamended and amended with different organic materials, by Fe K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy. The linear combination fitting and wavelet transform of EXAFS data revealed noticeable differences between unamended FSa and FSi + Cl fractions.

Spatially Resolved Organomineral Interactions across a Permafrost Chronosequence.

Permafrost contains a large (1700 Pg C) terrestrial pool of organic matter (OM) that is susceptible to degradation as global temperatures increase. Of particular importance is syngenetic Yedoma permafrost containing high OM content. Reactive iron phases promote stabilizing interactions between OM and soil minerals and this stabilization may be of increasing importance in permafrost as the thawed surface region ("active layer") deepens.

Dissolved Organic Matter Sorption and Molecular Fractionation by Naturally Occurring Bacteriogenic Iron (Oxyhydr)oxides.

Iron (oxyhydr)oxides are highly reactive, environmentally ubiquitous organic matter (OM) sorbents that act as mediators of terrestrial and aqueous OM cycling. However, current understanding of environmental iron (oxyhydr)oxide affinity for OM is limited primarily to abiogenic oxides. Bacteriogenic iron (oxyhydr)oxides (BIOs), common to quiescent waterways and soil redox transitions, possess a high affinity for oxyanions (i.

Formation of Cd precipitates on γ-AlO: Implications for Cd sequestration in the environment.

Apart from surface complexation, precipitation of minerals also plays an important role in reducing the mobility and transport of heavy metals in the environment. In this study, Cd(II) sorption species on surfaces of γ-AlO at pH 7.5 were characterized using multiple techniques.