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Silver (Ag) isotopes have the potential to provide useful insights into a diverse range of geological, environmental, and archaeological processes. This manuscript presents a novel technique that provides a simple, time-efficient, and accurate method for obtaining Ag isotope compositions of metallic gold (Au) samples. Unlike previous methodologies that favoured multiple ion exchange columns to purify and isolate Ag in nitrate form. This technique instead uses a single anion-exchange column, followed by the chemical conversion of Ag from chloride to nitrate form using the widely available reagents, ammonium hydroxide and ascorbic acid. This chemical conversion not only speeds up and simplifies sample processing allowing increased sample throughput, but importantly also significantly reduces the risk of Ag loss (and therefore user-induced isotopic fractionation) while converting the samples into a medium suitable for mass spectrometry. In this study, both pure Ag and native Au samples have been investigated, with Ag isotope compositions given relative the NIST SRM978a Ag standard. The long-term reproducibility of the in-house Sigma MON Ag solution was ε109Ag = 1.32 ± 0.31 (2 s.d.; n = 34), which is comparable to the precision achievable for unprocessed high-purity Ag samples with replicate analyses generating an average precision of ε109Ag = ± 0.25 (2 s.d.; n = 5). Comparable levels of precision were also achieved for natural Au samples, indicating that this methodology has no resolvable effect on the precision of the Ag isotope measurements. The natural Au standard CEZAg was used to test the external reproducibility of the chemical separation and conversion technique, yielding an average value of ε109Ag = 0.34 ± 0.13 (2 s.d.; n = 6), which is within analytical uncertainty of the previous determinations, demonstrating the accuracy of the new methodology. Furthermore, analysis of natural Au gold nuggets from the Fosterville Au Mine using the chemical conversion process described herein and a previously published multiple column method at a different institution produced consistent Ag isotope compositions, confirming the accuracy of the measurements generated using this method. [ABSTRACT FROM AUTHOR]

Author(s): Andrew G. Tomkins (corresponding author) [1]; Lara Bowlt [1]; Matthew Genge [2, 3]; Siobhan A. Wilson [1]; Helen E. A. Brand [4]; Jeremy L. Wykes [1, 4, 5] It [...]

Primary succession describes the establishment of new ecosystems through the colonization of barren substrates (Odum, [29]). The functional roles of these pioneer microbes are varied; for example, they can weather and detoxify environments to increase habitability, provide organic carbon and bioavailable nitrogen through carbon and nitrogen fixation, and form mutualistic relationships with plant species (Abdulla, [1]; Richardson & Simpson, [33]). In contrast, keystone microbial colonizers in alpine regions or glacier forelands create a more hospitable soil environment, achieved by physically altering the soil texture while chemically transforming major elements into more bioavailable forms (e.g., nitrogen fixation, carbon fixation or the solubilization and mineralization of the soil phosphorus pool) (Richardson & Simpson, [33]). Some metabolically flexible microorganisms may even modulate their energetic strategies during different successional stages; for example, in acid mine drainage, pioneering microorganisms such as I Acidithiobacillus i may shift from an initial hydrogen-fuelled colonization and acid production towards more specialized iron- and sulfide-based metabolism (Islam et al., [16]; Mielke et al., [28]). [Extracted from the article]