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At least 19 records

Carbon dioxide-enhanced metal release from kerogen

Heavy metals released from kerogen to produced water during oil/gas extraction have caused major environmental concerns. To curtail water usage and production in an operation and to use the same process for carbon sequestration, supercritical CO 2 (scCO 2 ) has been suggested as a fracking fluid or an oil/gas recovery agent. It has been shown previously that injection of scCO 2 into a reservoir may cause several chemical and physical changes to the reservoir properties including pore surface wettability, gas sorption capacity, and transport properties. Using molecular dynamics simulations, we here demonstrate that injection of scCO 2 might lead to desorption of physically adsorbed metals from kerogen structures. This process on one hand may impact the quality of produced water. On the other hand, it may enhance metal recovery if this process is used for in-situ extraction of critical metals from shale or other organic carbon-rich formations such as coal.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Effect of fluctuating redox conditions on trace metal release from wetland soils from South Carolina and stream sediments from Tennessee

Natural aquatic systems undergo fluctuating redox conditions due to microbial activity, varying water saturation levels, and nutrients dynamics. With fluctuating oxic and anoxic conditions, trace metals can be mobilized or sequestered in response to changes in iron and sulfur speciation and the concentrations and lability of organic carbon. We conducted a systematic laboratory-based microcosm study to examine the effect of redox fluctuations on trace metal mobility in samples collected from two different natural aquatic systems: riparian wetlands and a stream. We incubated water-saturated soils under three cycles of anoxic-oxic conditions (τanoxic:τoxic = 3) spanning 24 days and monitored the change in dissolved and bioavailable metal (copper (Cu), nickel (Ni), zinc (Zn), cobalt (Co), iron (Fe), and manganese (Mn)) concentrations. The dataset includes the results of the variation in metal concentrations due to redox fluctuations in wetland soils and stream sediments. Additionally, the variation in the bioavailable concentration of metals obtained using passive samplers based on diffuse gradient in thin-films technique is included in the dataset. We have also reported the change in the pH values and dissolved oxygen concentrations in the microcosms during the entire study of 24 days. The dataset also contains the dissolved organic carbon and sulfate concentrations, and the data on fractions of metals bound to reducible and oxidizable phases. For materials from both the wetlands and the stream, anoxic conditions favored Co and Zn release, which corresponded with the reductive dissolution of iron oxides. In contrast, dissolved Cu concentrations increased under oxic conditions for both sites and correlated positively with the release of sulfate. In wetland soils, dissolution of Fe (hydr)oxides increased Ni solubility; however, in stream sediments, Ni release occurred when sulfides or organic matter were oxidized. For stream sediments, each subsequent redox cycle increased the bioavailability of trace metals. Upon redox fluctuations in wetland soils, the bioavailability of Zn and Cu increased, whereas bioavailable Ni and Co decreased. This study illustrates that different trace metals display distinct bioavailability patterns during oxic-anoxic fluctuations in natural environments. The biogeochemical cycling of carbon and nitrogen in systems with redox fluctuations may be influenced by these patterns in trace metal availability in addition to the availability of electron donors and acceptors.

54 ENVIRONMENTAL SCIENCES↗

Facile Metal Release from Pore-Lining Phases Enables Unique Carbonate Zonation in a Basalt Carbon Mineralization Demonstration

Carbon-negative strategies such as geologic carbon sequestration in continental flood basalts offers a promising route to the removal of greenhouse gases, such as CO 2 , via safe and permanent storage as stable carbonates. This potential has been successfully demonstrated at a field scale at the Wallula Basalt Carbon Storage Pilot Project where supercritical CO 2 was injected into the Columbia River Basalt Group (CRBG). Here, we analyze recovered post-injection sidewall core cross-sections containing carbonate nodules using μ-XRF chemical mapping techniques that revealed compositional zonation within the nodules. The unique nature of the subsurface anthropogenic carbonates is highlighted by the near absence of Mg in an ankerite-like composition. Furthermore, a comparison between pre- and post-injection sidewall cores along with an in-depth chemical mapping of basalt pore lining cements provides a better understanding into the source and fate of critical cationic species involved in the precipitation of carbon mineralization products. Collectively, these results provide crucial insights into carbonate growth mechanisms under a time-dependent pore fluid composition. Finally, as such, these findings will enable parameterization of predictive models for future CO 2 sequestration efforts in reactive reservoirs around the world.

54 ENVIRONMENTAL SCIENCES↗

Influence of aluminum incorporation and aqueous conditions on metal ion release of high-Ni transition metal oxide nanomaterials

Developing a materials perspective of how to control the degradation and negative impact of complex metal oxides requires an integrated understanding of how these nanomaterials transform in the environment and interact with biological systems. Doping with aluminum is known to stabilize oxide materials, but has not been assessed cohesively from synthesis to environmental fate and biological impact. In the present study, the influence of aluminum doping on metal ion release from transition metal oxides was investigated by comparing aqueous transformations of lithium nickel cobalt aluminum oxide (LiNi 0.82 Co 0.15 Al 0.03 O 2 ; NCA) and lithium nickel cobalt oxide (LiNi 0.80 Co 0.20 O 2 ; NC) nanoparticles and by calculating the energetics of metal release using a density functional theory (DFT) and thermodynamics method. Two model environmental organisms were used to assess biological impact, and metal ion release was compared for NCA and NC nanoparticles incubated in their respective growth media: moderately hard reconstituted water (MHRW) for the freshwater invertebrate Daphnia magna (D. magna) and minimal growth medium for the Gram-negative bacterium Shewanella oneidensis MR-1 (S. oneidensis). Further, the amount of metal ions released was reduced for NCA compared to NC in MHRW, which correlated to changes in the modeled energetics of release upon Al substitution in the lattice. In minimal medium, metal ion release was approximately an order of magnitude higher compared to MHRW and was similar to the stoichiometry of the bulk nanoparticles for both NCA and NC. Interpretation of the release profiles and modeling indicated that the increase in total metal ion release and the reduced influence of Al doping arises from lactate complexation of metal ions in solution. The relative biological impacts of NC and NCA exposure for both S. oneidensis and D. magna were consistent with the metal release trends observed for minimal medium and MHRW, respectively. Together, these results demonstrate how a combined experimental and computational approach provides valuable insight into the aqueous transformations and biological impacts of complex metal oxide nanoparticles.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Effect of oxidation on the release of multiple metals from industrially polluted sediments and synchrotron-based evidence of Cu–S dynamic association

Disposal operations for industrially polluted sediments are usually accompanied by disturbance and resuspension, which can induce metal remobilization and secondary pollution. Evaluating the risk of metal release under various redox conditions is fundamental for predicting contaminant mobilization and guiding remediation measures. An abandoned oxidation pond, Yanjia Lake, China, was selected as a typical industrially polluted site. Re-suspension experiments were carried out by mixing polluted sediments with lake water under oxic or anoxic conditions, then investigating the effect of oxidation conditions on the release of multiple metals. Metal concentrations and aqueous chemistry in the overlying water were monitored. Synchrotron-based methods, including X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS), were used to characterize oxidation states and coordination conditions of metals in sediments. The release of metals, including Cr, Co, Ni, Cu, Zn, Se, Mo, Sn, Cd, and Pb, was enhanced under oxic vs. anoxic conditions. The XANES analysis revealed that elevated Cr and Zn concentrations under oxic conditions likely resulted from the oxidation of Cr(III) and oxidizing dissolution of ZnS, respectively. K-edge Cu XANES, S XANES, and Cu EXAFS analyses reconstructed the Cu–S association, indicating that S-related oxidation promoted Cu release and Cu–O partly replaced Cu–S in the sediment after a 7-day oxic treatment. The release of most metals was promoted under oxic conditions, resulting from the oxidation of sulfides and metals as indicated by aqueous and synchrotron-based evidence. The risk of secondary pollution is greatly enhanced under oxic conditions, which suggests that measures should be taken to minimize the redox disturbance during sediment remediation. This information can guide the management of sediments in Yanjia Lake and other contaminated sites with similar properties.

54 ENVIRONMENTAL SCIENCES↗

Dissolution kinetics of iron-, manganese-, and copper-containing synthetic hydroxyapatites

Micronutrient-substituted synthetic hydroxyapatite (SHA) is being evaluated by the National Aeronautics and Space Administration's (NASA) Advanced Life Support (ALS) Program for crop production on long-duration human missions to the International Space Station or for future Lunar or Martian outposts. The stirred-flow technique was utilized to characterize Ca, P, Fe, Mn, and Cu release characteristics from Fe-, Mn-, and Cu-containing SHA in deionized (DI) water, citric acid, and diethylene-triamine-pentaacetic acid (DTPA). Initially, Ca and P release rates decreased rapidly with time and were controlled by a non-SHA calcium phosphate phase(s) with low Ca/P solution molar ratios (0.91-1.51) relative to solid SHA ratios (1.56-1.64). At later times, Ca/P solution molar ratios (1.47-1.79) were near solid SHA ratios and release rates decreased slowly indicating that SHA controlled Ca and P release. Substituted SHA materials had faster dissolution rates relative to unsubstituted SHA. The initial metal release rate order was Mn >> Cu > Fe which followed metal-oxide/phosphate solubility suggesting that poorly crystalline metal-oxides/phosphates were dominating metal release. Similar metal release rates for all substituted SHA (approximately 0.01 cmol kg-1 min-1) at the end of the DTPA experiment indicated that SHA dissolution was supplying the metals into solution and that poorly crystalline metal-oxide/phosphates were not controlling metal release. Results indicate that non-SHA Ca-phosphate phases and poorly crystalline metal-oxide/phosphates will contribute Ca, P, and metals. After these phases have dissolved, substituted SHA will be the source of Ca, P, and metals for plants.

NASA Discipline Life Support Systems↗

Potential Chemical Impacts of Subsurface CO 2 : An Integrated Experimental and Numerical Assessment for a Case Study of the Ogallala Aquifer

Leakage from geologic CO 2 sequestration (GCS) reservoirs to overlying underground sources of drinking water (USDW) is a tangible risk. This study is an integrated assessment that combines column experiments and reactive transport simulations of sediments sampled from the Ogallala aquifer above an active commercial-scale GCS site (the Farnsworth Unit in northern Texas). Experimental and simulation results suggest that carbonate mineral (calcite and dolomite) dissolution is the most significant reaction following CO 2 intrusion, and is also the dominant source of trace metal release. Cation exchange is another key mechanism controlling trace metal release by cation interference. Most of the trace metals, including Ba, Sr, As, Pb, and Zn, show a short-term release and quickly drop to the baseline values, suggesting low risk to the overlying USDW quality. Other trace metals, such as Mn and U, exhibit a tangible increase of their concentrations in the beginning, and drop to a higher level compared to the baseline, which may become a potential concern of long-term USDW quality change with CO2introduction. This study provides a comprehensive example of combining laboratory experiments and simulations for assessment of CO 2 -sediment interactions with combined release mechanisms in shallow groundwater aquifers. Data presented here provides useful insights for quantitative risk assessment and effective public education regarding CO 2 geological sequestration, and trace metal reactive transport studies in shallow groundwater aquifers.

54 ENVIRONMENTAL SCIENCES↗

Analysis of Supercritical-Extracted Chelated Metal Ions From Mixed Organic-Inorganic Samples

Organic and inorganic contaminants of an environmental sample are analyzed by the same GC-MS instrument by adding an oxidizing agent to the sample to oxidize metal or metal compounds to form metal ions. The metal ions are converted to chelate complexes and the chelate complexes are extracted into a supercritical fluid such as CO2. The metal chelate extract after flowing through a restrictor tube is directly injected into the ionization chamber of a mass spectrometer, preferably containing a refractory metal filament such as rhenium to fragment the complex to release metal ions which are detected. This provides a fast, economical method for the analysis of metal contaminants in a sample and can be automated. An organic extract of the sample in conventional or supercritical fluid solvents can be detected in the same mass spectrometer, preferably after separation in a supercritical fluid chromatograph.

Sinha, Mahadeva P.↗

N-induced soil acidification triggers metal stimulation of soil methane oxidation in a temperate steppe ecosystem

Methane (CH 4 ) is a potent greenhouse gas, and it is well established that low nitrogen (N) stimulates- and high N suppresses CH 4 oxidation in grassland ecosystems. Here, in this study, we examined the response of CH 4 uptake to long-term (>10 years) multi-level N additions in a temperate steppe of northern China. The N impacts on CH 4 uptake transitioned from positive to negative at the N addition rate of 4 g N m -2 y -1 . However, the high-N suppression on CH 4 uptake was partially relieved when the continuous (>10 years) high N inputs (16 g N m -2 y -1 to 64 g N m -2 y -1 ) caused soil pH drop to < 5.7. Further experiments revealed that continuous high-N inputs acidified soil to pH < 5.7 that released metal ions to stimulate monooxygenase enzyme activity; therefore, the CH 4 oxidation suppression was partially relieved under continuous N loading. Structural equation model results confirmed that metal ions, such as Iron (Fe 3+ ), Manganese (Mn 4+ ), and Copper (Cu) desorbed by soil particles, were negatively correlated with soil pH while positively correlated with CH 4 oxidation under high N inputs. These analyses suggested that continuous high N inputs-induced soil acidification can release previously bounded metal elements that partially alleviated the N suppression on CH 4 uptake. The N-induced soil acidification impacts on CH 4 uptake might play a critical role in global CH 4 cycling and deserve further investigation as external N inputs continue climbing.

59 BASIC BIOLOGICAL SCIENCES↗

Geochemical and isotopic evidence for paleoredox conditions during deposition of the Devonian-Mississippian New Albany Shale, southern Indiana

The upper part of the New Albany Shale is divided into three members. In ascending order, these are (1) the Morgan Trail Member, a laminated brownish-black shale; (2) the Camp Run Member, an interbedded brownish-black and greenish-gray shale; and (3) the Clegg Creek Member, also a laminated brownish-black shale. The Morgan Trail and Camp Run Members contain 5% to 6% total organic carbon (TOC) and 2% sulfide sulfur. Isotopic composition of sulfide in these members ranges from -5.0% to -20.0%. C/S plots indicate linear relationships between abundances of these elements, with a zero intercept characteristic of sediments deposited in a non-euxinic marine environment. Formation of diagenetic pyrite was carbon limited in these members. The Clegg Creek Member contains 10% to 15% TOC and 2% to 6% sulfide sulfur. Isotopic compositions of sulfide range from -5.0% to -40%. The most negative values occur in the uppermost Clegg Creek Member and are characteristic of syngenetic pyrite, formed within an anoxic water column. Abundances of carbon and sulfur are greater and uncorrelated in this member, consistent with deposition in as euxinic environment. In addition, DOP (degree of pyritization) values suggest that formation of pyrite was generally iron limited throughout Clegg Creek deposition, but sulfur isotopes indicate that syngenetic (water-column) pyrite becomes an important component in the sediment only in the upper part of the member. At the top of the Clegg Creek Member, a zone of phosphate nodules and trace-metal enrichment coincides with maximal TOC values. During euxinic deposition, phosphate and trace metals accumulated below the chemocline because of limited vertical circulation in the water column. Increased productivity would have resulted in an increased flux of particulate organic matter to the sediment, providing an effective sink for trace metals in the water column. Phosphate and trace metals released from organic matter during early diagenesis resulted in precipitation of metal-rich phosphate nodules.

NASA Discipline Exobiology↗

Remote Optical Recession Measurement of Orion Thermal Protection System

For the Orion Multi-Purpose Crew Vehicle (MPCV) project, NASA is minimizing the use of onboard diagnostics, especially external sensors that penetrate the structure. Nonetheless, there is a desire to measure the Thermal Protection System (TPS) recession during reentry. One noninvasive technique currently under investigation is the insertion of indicator metals into the heatshield at varied depths and spatial locations. A remote (airborne) spectrometer detects the emissions from the ionized metal to reveal the time (thus depth) of the metal release. Innovative processing enables the emission features from trace amounts of the selected metals to be reliably detected against the complex and structured spectral background of the shock layer and ablated TPS material. The con-cept has been proven viable through ground testing at NASA HyMETS and AHF arc jet facilities using the Orion TPS material (Avcoat). This presentation highlights the parametric testing that was conducted to select the optimal indicator metals and to assess the accuracy of remote recession measurements using this technique. The CONOPS for integrating the technique into the Orion flight tests is also presented. This includes the onboard indicator metal "seeded plugs" and the offboard airborne sensor platform that would be deployed.

Scriven, Gordon↗

Iron, Manganese and Copper Release from Synthetic Hydroxyapatite

Kinetic stir-flow dissolution experiments were performed on iron- (Fe-SHA), manganese- (Mn-SHA), and copper- (Cu-SHA) containing synthetic hydroxyapatites. Solution treatments consisted of de-ionized water, citric acid and DTPA. Initially, Mn concentrations were higher than Cu concentrations and Fe concentrations were the lowest in all treatments. At later times Mn and Cu concentrations dropped in the DTPA treatment while Fe rose to the concentration similar to Mn and Cu. At all times, metal release concentrations in the water and citric acid treatments followed the trend of Mn>Cu>Fe. Rietveld analysis of x-ray diffraction data and ^31P NMR indicated that the metals substituted for Ca in the SHA structure. However, EPR data suggested that a metal (hydr)oxide phase existed either on the SHA surface or between the SHA crystallites. The metal concentration trend of Mn>Cu>Fe suggested that the initial solution metal concentrations are dependent on the dissolution of (hydr)oxides from SHA surfaces or between SHA crystallites. Similar metal concentrations at later times in the DTPA experiments suggests that metal concentrations were controlled by the release of Mn, Cu, or Fe from the SHA structure.

Sutter, B.↗

Simultaneous Insight into Dissolution and Aggregation of Metal Sulfide Nanoparticles through Single-Particle Inductively Coupled Plasma Mass Spectrometry

Nanoparticles (NPs) and their colloidal aggregates are ubiquitous and play important roles in the transport and release of metals. Knowledge of their dissolution rates and aggregation behavior in solution are crucial for better prediction of their fate in biogeochemical cycling, ecotoxicity, and environmental remediation. There are however significant technical challenges to accurately obtain such information as a result of the heterogeneity and highly dynamic transformation exhibited by NPs, particularly at relatively low particle concentrations in aqueous systems. Here, we quantitatively examine the simultaneous dissolution and aggregation behavior of metal sulfide NPs using single-particle inductively coupled plasma mass spectrometry (spICP–MS). We focus on nickel sulfide (NiS), with additional data presented for copper sulfide (CuS) and cobalt sulfide (CoS). The kinetics of metal release (dissolution and disaggregation) of NiS was fastest under strongly oxidizing conditions (from 0.04 to >3 min –1 with H 2 O 2 ) and were slower under near-neutral (HEPES buffer/H 2 O) and acidic (1 mM HNO 3 ) conditions (≤0.006 min –1 ). Metal release kinetics in HNO 3 was not faster than in H 2 O or HEPES, suggesting that the solution pH has an influence over both the dissolution kinetics of individual particles and the NP aggregation states, which in combination affect metal release rates over time. Between different metal sulfides, the measured metal release rates were largely consistent with predictions based on the crystallinity, solubility products, and specific surface areas of the NPs, following an order of CoS > NiS > CuS. Here, the spICP–MS approach described here can be easily applied to the characterization of metal release and aggregation of other NPs at low concentrations (~10 5 particles/mL) typically found in natural environments.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

The unusual metallic particles in Krymka LL3.0 chondrite

The composition, structure peculiarities, and possible scenario of formation of unusual metallic particles in Krymka LL3.0 are shown. In metal released from gentle crushed after removal of chondrules of Krymka LL3.0 chondrite matter, two types of unusual metallic particles were detected. The first type of particle mainly consists of coarse-grained (greater than or equal to 50 microns) kamacite and fine-grained (less than or equal to 10 microns) Ni-high (approximately 53 wt. percent) taenite. These particles have well-defined zonal structure: kamacite is in central part of particles whereas taenite is in outside and the grains of taenite form the mantle around kamacite. In the second type of particle Fe,Ni-phase contains only fine-grained Ni-rich taenite. In both particle types there are also fine-grained phosphate, troilite, and silicate. Both particle types have mostly rounded to subrounded form.

Fisenko, A. V.↗

Fundamental Insights into Cathode Stability: Linking Compositional Tuning and Local Coordination in Complex Metal Oxides under Aqueous Transformations

Compositional tuning of complex metal oxides in Li-ion battery materials influences their performance as well as their end-of-life behavior, in particular, the tendency to release toxic metal cations in aqueous solution. We modeled ternary variants of a parent LiCoO 2 delafossite structure by varying the metal identity and relative amounts. This yielded ten model formulations of Li(A 4/6 B 1/6 C 1/6 )O 2 , where the material is enriched with the A metal and doped with B and C, with Ni, Mn, Co, Fe, Al, V, and Ti as constituent metals. To assess their stability in aqueous conditions, metal release energetics were calculated using a combination of Density Functional Theory calculations and thermodynamics. Metal release in ternary oxides is dictated by subtle variations in the coordination environment of the leaving group. To identify governing chemical features across diverse compositions with varying local coordination environments, we leverage random forest regression and descriptor importance analysis. A key result is that metal–oxygen orbital hybridization, quantified using a projected density-of-states-derived descriptor, H d/p , provides a physically grounded measure of interaction strength that governs metal release energetics. This refined perspective goes beyond conventional oxidation state considerations and offers more robust insights for materials science. Finally, we model defect surface-bound O 2 dimer formation as a proxy for reactive oxygen species (ROS) generation. The results show that Ni-rich compositions more readily stabilize spin-polarized O 2 dimers, corroborating experimental reports of an increased ROS-driven biological response. In conclusion, our results establish a compositional and electronic basis for metal release and surface oxygen reactivity that form a rationale for complex metal oxide design principles.

36 MATERIALS SCIENCE↗

Chemical impacts of subsurface CO 2 and brine on shallow groundwater quality

Leakage from geologic CO 2 sequestration (GCS) sites to overlying shallow drinking water aquifers is a tangible risk. A primary purpose of this study is to assess the potential impacts of CO 2 leakage into a fresh-water aquifer with associated CO 2 -water-sediment interactions. Here, the study site is the Ogallala aquifer overlying an active demonstration-scale GCS site in north Texas, USA. Using the results of combined batch experiments and reactive transport simulations, we discuss the effects of salinity on potential trace metal release and the potential for groundwater quality recovery after leakage ceases.

54 ENVIRONMENTAL SCIENCES↗