Goldschmidt 2012 Conference Abstracts Rationalising nanoparticle sizes Yttrium mobility during weathering: measured by AFM, FlFFF and DLS: implications for riverine Y/Ho 1* 2 sample preparation, polydispersity MICHAEL G. BABECHUK , BALZ S. KAMBER , MIKE 3 and particle structure WIDDOWSON 1Laurentian University, Sudbury, ON, Canada (* presenting author) OHAMMED AALOUSHA AND AMIE EAD 2 M B * J L Trinity College Dublin, Dublin, Ireland 1 School of Geography, Earth and Environmental Sciences, 3The Open University, Milton Keynes, United Kingdom College of Life and Environmental Sciences, University of Birmingham, Birmingham, United Kingdom, Yttrium has similar geochemical properties to the lanthanides [email protected] (* presenting author) and closely mirrors the behaviour of its geochemical twin, Ho, in anhydrous magmatic systems. In the hydrosphere, however, Y is 8e.Towards the fundamentals of nanoparticle noteably less particle reactive than the lanthanides [1] and is more interactions with the living world: a life cycle perspective. mobile during chemical weathering as a result [e.g., 2]. Here, this behaviour is further explored using chemical transects through two This presentation will discuss the sources of variability in the basaltic weathering profiles in India that are preserved in different measured nanomaterial (NM) size by different analytical tools stages of alteration: the Bidar laterite profile (~50 m) and an including atomic force microscopy (AFM), dynamic light scattering incipient to intermediately weathered profile developed across two lava flows (~5 m) near Chhindwara. Both profiles were characterized (DLS) and flow-field flow fractionation (FlFFF). The results suggest using major element and high-precision trace element data to that differences in NM size measurements between different establish the progressive compositional changes during chemical analytical tools can be rationalised by taking into consideration (i) weathering. sample preparation, (ii) sample polydispersity and (iii) structural The parent rock Deccan Traps basalt of both profiles is properties of the NMs. chemically similar with an average Y/Ho ratio of 25.2 ± 1.1 in the Appropriate sample preparation is a key to obtain representative least-weathered samples. In the Chhindwara weathering profile, the particle size distributions (PSDs), and this may vary on a case by enhanced mobility of Y relative to the lanthanides is observed case basis. For AFM analysis, an ultracentrifugation method is the already at the incipient stages of weathering. The preferential loss of optimal method to prepare samples from diluted suspensions of Y continues during increasing weathering intensity in the profile as NMs (<1 mg L-1). For FlFFF, the overloading effect, particle- demonstrated by a strong anti-correlation between the chemical particle and particle-membrane interactions as well as nature of the index of alteration (CIA; ranging from 35-80) and the Y/Ho ratio calibration standards are important determinants of the quality of (ranging from ~25-23). Yttrium mobility is evident at the scale of data. For DLS, the quality of the fitting of the autocorrelation the profile as well as across a corestone-saprolite interface (< 1 m). function is a key issue in obtaining correct estimates of particle The Bidar laterite profile (CIA>90) has highly subchondritic Y/Ho size. Conversion of intensity PSD to number or volume PSD is ratios (19.4-14.7) with the exception of one sample in the mottled promising for determination of number and volume PSD, but zone with highly enriched REE abundances and a superchondritic hampered by uncertainties in solving and optimizing the Y/Ho ratio of 30.1. autocorrelation function fit. River waters have superchondritic Y/Ho ratios prior to reaching The differences between the z-average hydrodynamic diameter the estuary (where additional, much more extreme Y/Ho by DLS and the particle height by AFM can be accounted for by fractionation occurs due to the higher particle reactivity of the sample polydispersity. The ratio of z-average hydrodynamic HREE), indicating that the greater mobility of Y relative to the diameter: AFM particle height approaches 1.0 for monodisperse HREE during weathering may be sufficient to affect mass balance. samples and increases with sample polydispersity. A polydispersity Care must be taken to correctly identify the Y/Ho ratio of river index of 0.1 is suggested as a suitable limit above which DLS data no water due to the possibility of marine chemical sedimentary rocks in longer remains accurate. Conversion of the volume PSD by FlFFF- the drainage area and/or contamination from phosphate fertilizers. UV to number PSD helps to rationalise for some of the variability in Using previously published Y/Ho data from eastern Australia rivers the measured sizes. The remaining variability in the measured sizes [3,4] screened based on P content and salinity to minimize the can be attributed to structural variability in the particles and in this influence of these complications, a net superchondritic Y/Ho ratio case is mainly attributed to the thickness and permeability of the remains. Thus, the weathering behaviour of Y may be more important particles/surface coating. For citrate coated NMs, the dFlFFF/dAFM to the interpretation of riverine Y/Ho ratios than previously approaches 1 and the particles are described as hard spheres, considered. whereas for PVP coated NMs, the dFlFFF/dAFM deviates toward values greater than one, indicating that these particles are either permeable or non-spherical. [1] Nozaki et al. (1997) EPSL 148, 329-340. [2] Hill et al. (2000) Geology 28, 923-926. [3] Lawrence et al. (2006) Marine & Freshwater Research 57, 725-736. [4] Lawrence et al. (2006) Aquatic Geochemistry 12, 39-72. Mineralogical Magazine | www.minersoc.org 1443 Downloaded from http://pubs.geoscienceworld.org/minmag/article-pdf/76/6/1443/2919822/gsminmag.76.6.02-B.pdf by guest on 26 September 2021 Goldschmidt 2012 Conference Abstracts Multi-laboratory Comparison of Electron transfer and atom exchange Sequential Metals Extractions among Fe and Mn phases 1* 2 CAROL BABYAK , JENNIFER N. GABLE , KWOK-CHOI 1 2 3 4 5 JONATHAN E. BACHMAN *, DREW E. LATTA , PATRICK LEE , WILLIAM J. ROGERS , ROCK J. VITALE , AND 1 3 6 MICHELLE M. SCHERER , AND KEVIN M. ROSSO NEIL E. CARRIKER 1 Appalachian State University, Boone, North Carolina, United 1The University of Iowa, Civil and Environmental Engineering States, [email protected] (* presenting author) (*[email protected]) 2 Environmental Standards, Inc., Valley Forge, Pennsylvania, United 2Argonne National Laboratory, Biosciences ([email protected]) States, [email protected] 3Pacific Northwest National Laboratory, Chemical and Material 3 Tennessee Valley Authority, Muscle Shoals, Alabama, United Sciences ([email protected]) States, [email protected] 4 Tennessee Valley Authority, Muscle Shoals, Alabama, United States, [email protected] Fe and Mn are both common redox-active metals in environmental 5 Environmental Standards, Inc., Valley Forge, Pennsylvania, United systems, and Fe-Mn redox chemistry is an important consideration States, [email protected] when predicting fate and transport of contaminants. Recent work 6 Tennessee Valley Authority, Chattanooga, Tennessee, United has shown that electron transfer and atom exchange occurs States, [email protected] between aqueous Fe(II) and Fe(III) oxides and results in extensive recrystallization both with and without secondary mineral Abstract formation [1]. It is unclear, however, whether similar redox Following the December 2008 rupture of a coal fly ash processes occur among Fe and Mn phases that might result in retaining pond at the Tennessee Valley Authority (TVA) Kingston incorporation and release of Fe in Mn oxides, or conversely, Fossil Plant near Harriman, Tennessee, a comprehensive monitoring incorporation and release of Mn in Fe oxides. Furthermore, it effort was intiated to evaluate impact of the release on the appears unknown whether the reaction of aqueous Mn(II) with Mn surrounding aquatic environment. The sequential extraction oxides leads to similar atom exchange and recrystallization as has procedure developed by Querol et. al [1] was utilized by TVA’s been observed for the reaction of aqueous Fe(II) with Fe(III) contracted laboratory and by Appalachian State University (ASU) oxides [2]. researchers to evaluate bioavailability of ash-related trace metals in We are exploring the mechanisms driving the redox reactions sediments impacted by the release. of Mn(II)/Fe-oxides, Fe(II)/Mn-oxides, and Mn(II)/Mn-oxides Sediment samples collected in 2009 were split and submitted to using 57Fe Mossbauer spectroscopy and isotope tracer approaches. ASU and to TVA’s contracted laboratory for sequential extraction We have found that Mn-incorporated in goethite is released in the and subsequent metals analysis. This paper presents a comparison of presence of aqueous Fe(II), similar to what has recently been the laboratories’ data using the same method. demonstrated for Ni in goethite [3]. These experiments will In 2011, several of the 2009 sediment sampling locations were provide a more fundamental understanding of the reactivity at revisited; these 2011 sediment samples were subjected to sequential mineral-water interfaces, in addition to providing a model for trace extraction by ASU following the same procedure as used for the metal incorporation and release in Mn and Fe oxides. 2009 samples. This paper also includes comparisons