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1. Acetaminophen and caffeine removal by MnO x(s) and GAC media in column experiments

   https://doi.org/10.1039/d0ew00689k  

   Miera, Rachael ; Shaikh, Nabil ; Artyushkova, Kateryna ; Ali, Abdul-Mehdi S. ; Santoro, Carlo ; Thomson, Bruce M. ; Howe, Kerry J. ; Cerrato, José M. ( January 2021 , Environmental Science: Water Research & Technology)

   null (Ed.)

   The objective of this study was to investigate the application of manganese oxide [MnO x(s) ] and granular activated carbon (GAC) media for the removal of caffeine and acetaminophen from water. Organic contaminants of emerging concern represent a developing issue due to their effects on human health and the environment. Manganese oxides are effective for water treatment because of their ability to mediate adsorption and oxidation–reduction reactions for many organic and inorganic constituents. Laboratory scale column experiments were performed using different combinations of commercial MnO x(s) and GAC for assessing the removal of caffeine and acetaminophen, and the subsequent release of soluble Mn due to the reductive dissolution of MnO x(s) . The removal of acetaminophen was detected for all media combinations investigated. However, the removal of caffeine by adsorption only occurred in columns containing GAC media. There was no removal of caffeine in columns containing only MnO x(s) media. Manganese release occurred in columns containing MnO x(s) media, but concentrations were below the secondary drinking water standard of 50 μg L −1 set by the US Environmental Protection Agency. Soluble Mn released from a first process by MnO x(s) media column was removed through adsorption into the GAC media used in a second process. The results of this investigation are relevant for implementation of MnO x(s) and GAC media combinations as an effective treatment process to remove organic contaminants from water. 

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2. Florida mangrove saltmarsh reference surface soils

   https://doi.org/10.6073/pasta/0e08cbe07c84488cb7b9dd16669946d0  

   Lewis, David Bruce ( January 2021 , Environmental Data Initiative)

   Site description. This data package consists of data obtained from sampling surface soil (the 0-7.6 cm depth profile) in black mangrove (Avicennia germinans) dominated forest and black needlerush (Juncus roemerianus) saltmarsh along the Gulf of Mexico coastline in peninsular west-central Florida, USA. This location has a subtropical climate with mean daily temperatures ranging from 15.4 °C in January to 27.8 °C in August, and annual precipitation of 1336 mm. Precipitation falls as rain primarily between June and September. Tides are semi-diurnal, with 0.57 m median amplitudes during the year preceding sampling (U.S. NOAA National Ocean Service, Clearwater Beach, Florida, station 8726724). Sea-level rise is 4.0 ± 0.6 mm per year (1973-2020 trend, mean ± 95 % confidence interval, NOAA NOS Clearwater Beach station). The A. germinans mangrove zone is either adjacent to water or fringed on the seaward side by a narrow band of red mangrove (Rhizophora mangle). A near-monoculture of J. roemerianus is often adjacent to and immediately landward of the A. germinans zone. The transition from the mangrove to the J. roemerianus zone is variable in our study area. An abrupt edge between closed-canopy mangrove and J. roemerianus monoculture may extend for up to several hundred meters in some locations, while other stretches of ecotone present a gradual transition where smaller, widely spaced trees are interspersed into the herbaceous marsh. Juncus roemerianus then extends landward to a high marsh patchwork of succulent halophytes (including Salicornia bigellovi, Sesuvium sp., and Batis maritima), scattered dwarf mangrove, and salt pans, followed in turn by upland vegetation that includes Pinus sp. and Serenoa repens. Field design and sample collection. We established three study sites spaced at approximately 5 km intervals along the western coastline of the central Florida peninsula. The sites consisted of the Salt Springs (28.3298°, -82.7274°), Energy Marine Center (28.2903°, -82.7278°), and Green Key (28.2530°, -82.7496°) sites on the Gulf of Mexico coastline in Pasco County, Florida, USA. At each site, we established three plot pairs, each consisting of one saltmarsh plot and one mangrove plot. Plots were 50 m^2 in size. Plots pairs within a site were separated by 230-1070 m, and the mangrove and saltmarsh plots composing a pair were 70-170 m apart. All plot pairs consisted of directly adjacent patches of mangrove forest and J. roemerianus saltmarsh, with the mangrove forests exhibiting a closed canopy and a tree architecture (height 4-6 m, crown width 1.5-3 m). Mangrove plots were located at approximately the midpoint between the seaward edge (water-mangrove interface) and landward edge (mangrove-marsh interface) of the mangrove zone. Saltmarsh plots were located 20-25 m away from any mangrove trees and into the J. roemerianus zone (i.e., landward from the mangrove-marsh interface). Plot pairs were coarsely similar in geomorphic setting, as all were located on the Gulf of Mexico coastline, rather than within major sheltering formations like Tampa Bay, and all plot pairs fit the tide-dominated domain of the Woodroffe classification (Woodroffe, 2002, "Coasts: Form, Process and Evolution", Cambridge University Press), given their conspicuous semi-diurnal tides. There was nevertheless some geomorphic variation, as some plot pairs were directly open to the Gulf of Mexico while others sat behind keys and spits or along small tidal creeks. Our use of a plot-pair approach is intended to control for this geomorphic variation. Plot center elevations (cm above mean sea level, NAVD 88) were estimated by overlaying the plot locations determined with a global positioning system (Garmin GPS 60, Olathe, KS, USA) on a LiDAR-derived bare-earth digital elevation model (Dewberry, Inc., 2019). The digital elevation model had a vertical accuracy of ± 10 cm (95 % CI) and a horizontal accuracy of ± 116 cm (95 % CI). Soil samples were collected via coring at low tide in June 2011. From each plot, we collected a composite soil sample consisting of three discrete 5.1 cm diameter soil cores taken at equidistant points to 7.6 cm depth. Cores were taken by tapping a sleeve into the soil until its top was flush with the soil surface, sliding a hand under the core, and lifting it up. Cores were then capped and transferred on ice to our laboratory at the University of South Florida (Tampa, Florida, USA), where they were combined in plastic zipper bags, and homogenized by hand into plot-level composite samples on the day they were collected. A damp soil subsample was immediately taken from each composite sample to initiate 1 y incubations for determination of active C and N (see below). The remainder of each composite sample was then placed in a drying oven (60 °C) for 1 week with frequent mixing of the soil to prevent aggregation and liberate water. Organic wetland soils are sometimes dried at 70 °C, however high drying temperatures can volatilize non-water liquids and oxidize and decompose organic matter, so 50 °C is also a common drying temperature for organic soils (Gardner 1986, "Methods of Soil Analysis: Part 1", Soil Science Society of America); we accordingly chose 60 °C as a compromise between sufficient water removal and avoidance of non-water mass loss. Bulk density was determined as soil dry mass per core volume (adding back the dry mass equivalent of the damp subsample removed prior to drying). Dried subsamples were obtained for determination of soil organic matter (SOM), mineral texture composition, and extractable and total carbon (C) and nitrogen (N) within the following week. Sample analyses. A dried subsample was apportioned from each composite sample to determine SOM as mass loss on ignition at 550 °C for 4 h. After organic matter was removed from soil via ignition, mineral particle size composition was determined using a combination of wet sieving and density separation in 49 mM (3 %) sodium hexametaphosphate ((NaPO_3)_6) following procedures in Kettler et al. (2001, Soil Science Society of America Journal 65, 849-852). The percentage of dry soil mass composed of silt and clay particles (hereafter, fines) was calculated as the mass lost from dispersed mineral soil after sieving (0.053 mm mesh sieve). Fines could have been slightly underestimated if any clay particles were burned off during the preceding ignition of soil. An additional subsample was taken from each composite sample to determine extractable N and organic C concentrations via 0.5 M potassium sulfate (K_2SO_4) extractions. We combined soil and extractant (ratio of 1 g dry soil:5 mL extractant) in plastic bottles, reciprocally shook the slurry for 1 h at 120 rpm, and then gravity filtered it through Fisher G6 (1.6 μm pore size) glass fiber filters, followed by colorimetric detection of nitrite (NO_2^-) + nitrate (NO_3^-) and ammonium (NH_4^+) in the filtrate (Hood Nowotny et al., 2010,Soil Science Society of America Journal 74, 1018-1027) using a microplate spectrophotometer (Biotek Epoch, Winooski, VT, USA). Filtrate was also analyzed for dissolved organic C (referred to hereafter as extractable organic C) and total dissolved N via combustion and oxidation followed by detection of the evolved CO_2 and N oxide gases on a Formacs HT TOC/TN analyzer (Skalar, Breda, The Netherlands). Extractable organic N was then computed as total dissolved N in filtrate minus extractable mineral N (itself the sum of extractable NH_4-N and NO_2-N + NO_3-N). We determined soil total C and N from dried, milled subsamples subjected to elemental analysis (ECS 4010, Costech, Inc., Valencia, CA, USA) at the University of South Florida Stable Isotope Laboratory. Median concentration of inorganic C in unvegetated surface soil at our sites is 0.5 % of soil mass (Anderson, 2019, Univ. of South Florida M.S. thesis via methods in Wang et al., 2011, Environmental Monitoring and Assessment 174, 241-257). Inorganic C concentrations are likely even lower in our samples from under vegetation, where organic matter would dilute the contribution of inorganic C to soil mass. Nevertheless, the presence of a small inorganic C pool in our soils may be counted in the total C values we report. Extractable organic C is necessarily of organic C origin given the method (sparging with HCl) used in detection. Active C and N represent the fractions of organic C and N that are mineralizable by soil microorganisms under aerobic conditions in long-term soil incubations. To quantify active C and N, 60 g of field-moist soil were apportioned from each composite sample, placed in a filtration apparatus, and incubated in the dark at 25 °C and field capacity moisture for 365 d (as in Lewis et al., 2014, Ecosphere 5, art59). Moisture levels were maintained by frequently weighing incubated soil and wetting them up to target mass. Daily CO_2 flux was quantified on 29 occasions at 0.5-3 week intervals during the incubation period (with shorter intervals earlier in the incubation), and these per day flux rates were integrated over the 365 d period to compute an estimate of active C. Observations of per day flux were made by sealing samples overnight in airtight chambers fitted with septa and quantifying headspace CO_2 accumulation by injecting headspace samples (obtained through the septa via needle and syringe) into an infrared gas analyzer (PP Systems EGM 4, Amesbury, MA, USA). To estimate active N, each incubated sample was leached with a C and N free, 35 psu solution containing micronutrients (Nadelhoffer, 1990, Soil Science Society of America Journal 54, 411-415) on 19 occasions at increasing 1-6 week intervals during the 365 d incubation, and then extracted in 0.5 M K_2SO_4 at the end of the incubation in order to remove any residual mineral N. Active N was then quantified as the total mass of mineral N leached and extracted. Mineral N in leached and extracted solutions was detected as NH_4-N and NO_2-N + NO_3-N via colorimetry as above. This incubation technique precludes new C and N inputs and persistently leaches mineral N, forcing microorganisms to meet demand by mineralizing existing pools, and thereby directly assays the potential activity of soil organic C and N pools present at the time of soil sampling. Because this analysis commences with disrupting soil physical structure, it is biased toward higher estimates of active fractions. Calculations. Non-mobile C and N fractions were computed as total C and N concentrations minus the extractable and active fractions of each element. This data package reports surface-soil constituents (moisture, fines, SOM, and C and N pools and fractions) in both gravimetric units (mass constituent / mass soil) and areal units (mass constituent / soil surface area integrated through 7.6 cm soil depth, the depth of sampling). Areal concentrations were computed as X × D × 7.6, where X is the gravimetric concentration of a soil constituent, D is soil bulk density (g dry soil / cm^3), and 7.6 is the sampling depth in cm. 

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3. Hardware, methodology and applications of 2 + D backscatter Mössbauer spectroscopy with simultaneous x-ray and γ-ray detection

   https://doi.org/10.1088/1361-6501/ad044b  

   O’Brien, Jack ; Ahmadian Baghbaderani, Hasan ; Keller, Frederico O. ; Dempsey, Nora ; H Lewis, Laura ; Stamenov, Plamen ( November 2023 , Measurement Science and Technology)

   A unique method is presented for the acquisition and analysis of⁵⁷Fe backscatter Mössbauer spectra with simultaneous detection of the resonant 14.4 keVγ-rays and the characteristic 6.4 keV x-rays, using a custom-built multi-parameter analyser constructed on the basis of commercial analogue to digital converters and high-speed digital latches. The system allows for the simultaneous registration of Doppler-modulation velocities and photon energies, with up to 4096 and 8192 digital channels respectively. This arrangement is in contrast to most related systems, which detect at a single narrow energy window per detector. Samples of arbitrary atomic structure, morphology and surface topography can be studied without altering the setup or the analysis procedure, provided that the samples are at least micrometre sized. The hardware and software that are used to acquire data with minimal dead time are described and the custom and self-contained methods for post-measurement energy discrimination, background correction and velocity-axis folding are discussed. The data are fit using a general Hamiltonian model for the nuclear energy levels of⁵⁷Fe and a quantum mechanical description of the angular momentum coupling is utilised, with consideration of the crystalline and chemical disorder of the sample under examination. Three examples of distinct magnetic systems, with thicknesses ranging from$5\text{μ}$m to 6 mm, that were studied using this method are presented, these are: an amorphous CoFeB-based ribbon with ultra-soft coercivity for high-frequency applications, magnetically hard Nd-Fe-B thick films on Si substrates, examined in both as-deposited and annealed states, and a sample from the nickel-rich iron meteorite NWA 6259 that contains the atomically ordered, elevated coercivity,$L{1}_0$phase of FeNi, tetrataenite. The wide applicability and usefulness of this method is thus demonstrated on three distinct sample morphologies that required little to no surface preparation prior to examination.

    

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4. Groundwater input drives large variance in soil manganese concentration and reactivity in a forested headwater catchment

   https://doi.org/10.1002/saj2.20439  

   Bourgault, Rebecca R. ; Ross, Donald S. ; Bailey, Scott W. ; Perdrial, Nicolas ; Bower, Jennifer ( September 2022 , Soil Science Society of America Journal)

   In headwater catchments, surface groundwater discharge areas have unique soil biogeochemistry and can be hot spots for solute contribution to streams. Across the northeastern United States, headwater hillslopes with surface groundwater discharge were enriched in soil Mn, including Watershed 3 of Hubbard Brook Experimental Forest, New Hampshire. Soils of this site were investigated along a grid to determine extent of Mn‐rich zone(s) and relationships to explanatory variables using ordinary kriging. The O and B horizons were analyzed for total secondary Mn and Fe, Cr oxidation potential, total organic C, moisture content, wetness ratio, and pH. Two Mn hot spots were found: a poorly drained, flowing spring (Location A); and a moderately well‐drained swale (Location B). Both had ∼6,000–9,000 mg Mn kg^–1soil. However, Location A had high Cr oxidation potential (a measure of Mn reactivity), whereas Location B did not. Location C, a poorly drained seep with slow‐moving water, had lower Mn content and Cr oxidation potential. Manganese‐rich soil particles were analyzed using X‐ray absorption near‐edge structure and micro‐X‐ray diffraction; the dominant oxidation state was Mn(IV), and the dominant Mn oxide species was a layer‐type Mn oxide (L‐MnO₂). We propose input of Mn(II) with groundwater, which is oxidized by soil microbes. Studies of catchment structure and response could benefit from identifying hot spots of trace metals, sourced mainly from parent material but which accumulate according to hydropedologic conditions. Small‐scale variation in Mn enrichment due to groundwater and microtopography appears to be more important than regional‐scale variation due to air pollution.

    

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5. Electrochemically Triggered Metal–Insulator Transition between VO 2 and V 2 O 5

   https://doi.org/10.1002/adfm.201803024  

   Lu, Qiyang ; Bishop, Sean R. ; Lee, Dongkyu ; Lee, Shinbuhm ; Bluhm, Hendrik ; Tuller, Harry L. ; Lee, Ho Nyung ; Yildiz, Bilge ( June 2018 , Advanced Functional Materials)

   Distinct properties of multiple phases of vanadium oxide (VO_x) render this material family attractive for advanced electronic devices, catalysis, and energy storage. In this work, phase boundaries of VO_xare crossed and distinct electronic properties are obtained by electrochemically tuning the oxygen content of VO_xthin films under a wide range of temperatures. Reversible phase transitions between two adjacent VO_xphases, VO₂and V₂O₅, are obtained. Cathodic biases trigger the phase transition from V₂O₅to VO₂, accompanied by disappearance of the wide band gap. The transformed phase is stable upon removal of the bias while reversible upon reversal of the electrochemical bias. The kinetics of the phase transition is monitored by tracking the time‐dependent response of the X‐ray absorption peaks upon the application of a sinusoidal electrical bias. The electrochemically controllable phase transition between VO₂and V₂O₅demonstrates the ability to induce major changes in the electronic properties of VO_xby spanning multiple structural phases. This concept is transferable to other multiphase oxides for electronic, magnetic, or electrochemical applications.

    

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