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42 results on '"Gorra, Roberta"'

10. Characterization of organic-rich mineral debris revealed by rapid glacier retreat, Indren Glacier, European Alps

Author

Freppaz, Michele; https://orcid.org/0000-0002-4290-6850, Williams, Mark W; https://orcid.org/0000-0002-9439-8480, Gabrieli, Jacopo; https://orcid.org/0000-0001-6230-5668, Gorra, Roberta; https://orcid.org/0000-0002-7007-7113, Mania, Ilaria; https://orcid.org/0000-0001-8723-0930, Ascher-Jenull, Judith; https://orcid.org/0000-0003-0127-8058, Egli, Markus, Celi, Luisella; https://orcid.org/0000-0002-2365-3317, Freppaz, Michele; https://orcid.org/0000-0002-4290-6850, Williams, Mark W; https://orcid.org/0000-0002-9439-8480, Gabrieli, Jacopo; https://orcid.org/0000-0001-6230-5668, Gorra, Roberta; https://orcid.org/0000-0002-7007-7113, Mania, Ilaria; https://orcid.org/0000-0001-8723-0930, Ascher-Jenull, Judith; https://orcid.org/0000-0003-0127-8058, Egli, Markus, and Celi, Luisella; https://orcid.org/0000-0002-2365-3317

Abstract

In the summer of 2003 and 2004, characterized by a rapid glacier retreat, a stony surface covered by well-structured organic-rich mineral debris was observed very close to the Indren glacier terminus (Monte Rosa Massif, NW Italy, 3100 m ASL), on an area covered by the glacier tongue till the year before. The origin and type of this organic-rich material were investigated, in order to detect their characteristics, potential sources and fate within the foreland system. The deposits were dated using Carbon-14 and analyzed for the chemical characteristics of the organic component, the elemental composition of the mineral fraction and presence of microbial markers. The material, granular and dark in color, had a total organic carbon (TOC) content ranging between 17.4 ± 0.39 and 28.1 ± 0.63 g kg$^{−1}$ dry weight (dw), significantly higher than the surrounding glacial till (~ 1.4 g kg$^{−1}$ dw), although only 0.33% of it was in water soluble form. Microbial carbon (C) and nitrogen (N) accounted for 10.6% and 3.13% of TOC and total N, respectively. Dissolved nitrogen (N), mainly present as ammonium, represented 2.40% of the total N. The low aromatic component and large presence of nitrogen (N)-derived compounds suggested that most of the organic carbon (OC) in these organic-rich mineral deposits was derived from microbial cells, although the high average radiocarbon age of about 2900 years may also point to the contribution of aeolian depositions of anthropogenic or natural origin. Elemental composition and the crustal enrichment factor of trace elements in the mineral fraction of the aggregates corroborated the hypothesis that most part of the accumulated material derived from ice meltwater. Some indicators of the colonization of these deposits by microbial communities were also reported, from the abundance of DNA and phylogenetic markers, to the presence of bacterial taxa commonly able to thrive in similar habitats. All these elements suggested that such kind of deposit

Published
2021

15. Complex coupled metabolic and prokaryotic community responses to increasing temperatures in anaerobic marine sediments: critical temperatures and substrate changes

Author

Roussel, Erwan, Cragg, Barry A., Webster, Gordon, Sass, Henrik, Tang, Xiaohong, Williams, Angharad S., Gorra, Roberta, Weightman, Andrew J., and Parkes, R. John

Subjects
mineralisation, sediment, temperature, chemoorganotrophic, sulphate reduction, anaerobic processes, acetogenesis, methanogenesis, chemolithotrophic
Abstract

The impact of temperature (0 - 80°C) on anaerobic biogeochemical processes and prokaryotic communities in marine sediments (tidal flat) was investigated in slurries for up to 100 days. Temperature had a non-linear effect on biogeochemistry and prokaryotes with rapid changes over small temperature intervals. Some activities (e.g. methanogenesis) had multiple “windows” within a large temperature range (~10 - 80°C). Others, including acetate oxidation, had maximum activities within a temperature zone, which varied with electron acceptor (metal oxide [up to ~34°C] and sulphate [up to ~50°C]). Substrates for sulphate reduction changed from predominantly acetate below, and H2 above, a 43°C critical temperature; along with changes in activation energies and types of sulphate-reducing Bacteria. Above ~43°C, methylamine metabolism ceased with changes in methanogen types and increased acetate concentrations (>1mM). Abundances of uncultured Archaea, characteristic of deep marine sediments (e.g. MBGD Euryarchaeota, ‘Bathyarchaeota’) changed, indicating their possible metabolic activity and temperature range. Bacterial cell numbers were consistently higher than archaeal cells and both decreased above ~15°C. Substrate addition stimulated activities, widened some activity temperature ranges (methanogenesis) and increased bacterial (x10) more than archaeal cell numbers. Hence, additional organic matter input from climate-related eutrophication may amplify the impact of temperature increases on sedimentary biogeochemistry.

Published
2015

37. Le pedo-tecnologie

Author

Gorra, Roberta

Subjects
pedo-tecnologie, depurazione, bioremediation, acque reflue
Published
2003

41. Enrichment and cultivation of prokaryotes associated with the sulphate-methane transition zone of diffusion-controlled sediments of Aarhus Bay, Denmark, under heterotrophic conditions

Author

Webster, Gordon, primary, Sass, Henrik, additional, Cragg, Barry A., additional, Gorra, Roberta, additional, Knab, Nina J., additional, Green, Christopher J., additional, Mathes, Falko, additional, Fry, John C., additional, Weightman, Andrew J., additional, and Parkes, R. John, additional

Published
2011
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