Biological role in the transformation of platinum-group mineral grains

Reith, Frank; Zammit, Carla M.; Shar, Sahar Saad; Etschmann, Barbara; Bottrill, R. S.; Southam, Gordon; Ta, Christine; Kilburn, Matt R.; Oberthür, Thomas; Ball, Andrew S.; Brugger, Joël

doi:10.1038/ngeo2679

Cited by 52 publications

(49 citation statements)

References 25 publications

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“…Surprisingly, the n-alkanes C 14 to C 24 are present in higher proportions than nC 27 , nC 29 , and nC 31 , which is unusual. The high proportions of nC 14 and nC 15 are particularly noticeable given that their melting points are 5.9 and 9.9 • C, respectively. nC 16 and nC 17 with melting points of 18.2 and 21 • C are also present.…”

Section: Resultsmentioning

confidence: 99%

“…C For this we would assume that the lighter alkanes <C 14 are sufficiently liquid to drain through the soil and that the alkanes C 14 -C 17 are sufficiently viscous that they do not drain away or are being produced at a sufficient rate to compensate for any loss.…”

Section: Resultsmentioning

confidence: 99%

“…Aware of the abundant organic material and microbial fauna beneath the tropical rain forest cover of the intrusion and the ease with which the PGE react with organic materials [9,10], some studies [11][12][13] have examined the possible role of humic and fulvic acid in taking the PGE into solution at 25 • C. It is clearly possible for the PGE to enter solution under these conditions within a short time frame. Importantly, recent work has shown the ability of bacteria to play a part in the growth of PGM [14,15]. There is a problem in developing an overall mechanism because there is evidence of different stages in the alteration and of carbon atoms with the hydrogen atoms attached along the length.…”

Section: Introductionmentioning

confidence: 99%

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C14–22 n-Alkanes in Soil from the Freetown Layered Intrusion, Sierra Leone: Products of Pt Catalytic Breakdown of Natural Longer Chain n-Alkanes?

Bowles

Giże³

2018

Minerals

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Abstract:Soil above a platinum-group element (PGE)-bearing horizon within the Freetown Layered Intrusion, Sierra Leone, contains anomalous concentrations of n-alkanes (C n H 2n+2 ) in the range C 14 to C 22 not readily attributable to an algal or lacustrine origin. Longer chain n-alkanes (C 23 to C 31 ) in the soil were derived from the breakdown of leaf litter beneath the closed canopy humid tropical forest. Spontaneous breakdown of the longer chain n-alkanes to form C 14-22 n-alkanes without biogenic or abiogenic catalysts is unlikely as the n-alkanes are stable. In the Freetown soil, the catalytic properties of the PGE (Pt in particular) may lower the temperature at which oxidation of the longer chain n-alkanes can occur. Reaction between these n-alkanes and Pt species, such as Pt 2+ (H 2 O) 2 (OH) 2 and Pt 4+ (H 2 O) 2 (OH) 4 can bend and twist the alkanes, and significantly lower the Heat of Formation. Microbial catalysis is a possibility. Since a direct organic geochemical source of the lighter n-alkanes has not yet been identified, this paper explores the theoretical potential for abiogenic Pt species catalysis as a mechanism of breakdown of the longer n-alkanes to form C 14-22 alkanes. This novel mechanism could offer additional evidence for the presence of the PGE in solution, as predicted by soil geochemistry.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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C14–22 n-Alkanes in Soil from the Freetown Layered Intrusion, Sierra Leone: Products of Pt Catalytic Breakdown of Natural Longer Chain n-Alkanes?

Bowles

Giże³

2018

Minerals

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“…The question remains: does this similar geochemical behaviour extend to low temperature, i.e., Earth surface weathering conditions? Recent work on placer platinum grains indicates that weathering, including the biogeochemical cycling of platinum does occur, albeit to a much lesser extent than gold [23][24][25].…”

Section: Introductionmentioning

confidence: 99%

Immobilisation of Platinum by Cupriavidus metallidurans

et al. 2018

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Abstract:The metal resistant bacterium Cupriavidus metallidurans CH34, challenged with aqueous platinous and platinic chloride, rapidly immobilized platinum. XANES/EXAFS analysis of these reaction systems demonstrated that platinum binding shifted from chloride to carboxyl functional groups within the bacteria. Pt(IV) was more toxic than Pt(II), presumably due to the oxidative stress imparted by the platinic form. Platinum immobilisation increased with time and with increasing concentrations of platinum. From a bacterial perspective, intracellular platinum concentrations were two to three orders of magnitude greater than the fluid phase, and became saturated at almost molar concentrations in both reaction systems. TEM revealed that C. metallidurans was also able to precipitate nm-scale colloidal platinum, primarily along the cell envelope where energy generation/electron transport occurs. Cells enriched in platinum shed outer membrane vesicles that were enriched in metallic, colloidal platinum, likely representing an important detoxification strategy. The formation of organo-platinum compounds and membrane encapsulated nanophase platinum, supports a role for bacteria in the formation and transport of platinum in natural systems, forming dispersion halos important to metal exploration.

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“…It is clearly possible for the PGE to enter solution under these conditions within a short time frame. Importantly, recent work has shown the ability of bacteria to play a part in the growth of PGM [14,15]. There is a problem in developing an overall mechanism because there is evidence of different stages in the alteration and re-growth process but the connections between these stages are circumstantial.…”

Section: Introductionmentioning

confidence: 99%

C14-22 n-alkanes in Soil from the Freetown Layered Intrusion, Sierra Leone: Products of Pt Catalytic Breakdown of Natural Longer Chain n-alkanes?

Bowles¹,

Bowles²,

Giże³

2018

Preprint

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:Soil above a platinum-group element (PGE)-bearing horizon within the Freetown Layered Intrusion, Sierra Leone contains anomalous concentrations of n-alkanes (CnH2n+2) in the range C14 to C22 not readily attributable to an algal or lacustrine origin. Longer chain nalkanes (C23 to C31) in the soil were derived from the breakdown of leaf litter beneath the closed canopy humid tropical forest. Spontaneous breakdown of the longer chain n-alkanes to form C14-22 n-alkanes without biogenic or abiogenic catalysts is unlikely as the n-alkanes are stable. In the Freetown soil, the catalytic properties of the PGE (Pt in particular) may lower the temperature at which oxidation of the longer chain n-alkanes can occur. Reaction between these n-alkanes and Pt species such as Pt 2+ (H2O)2(OH)2 and Pt 4+ (H2O)2(OH)4 can bend and twist the alkanes, and significantly lower the Heat of Formation. Acknowledging the possibility of microbial catalysis and the difficulty of identifying a direct organic geochemical source of the lighter n-alkanes, this paper explores the theoretical potential for abiogenic Pt species catalysis as a mechanism of breakdown of the longer n-alkanes to form C14-22 alkanes. This novel mechanism could substantiate the presence of the PGE in solution predicted by soil geochemistry and illustrate processes involving the PGE. Graphical AbstractThe anomalous proportion of C14 to C22 n-alkanes with a C31 molecule distorted by Pt 4+ (H2O)2(OH)4

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Biological role in the transformation of platinum-group mineral grains

Cited by 52 publications

References 25 publications

C14–22 n-Alkanes in Soil from the Freetown Layered Intrusion, Sierra Leone: Products of Pt Catalytic Breakdown of Natural Longer Chain n-Alkanes?

C14–22 n-Alkanes in Soil from the Freetown Layered Intrusion, Sierra Leone: Products of Pt Catalytic Breakdown of Natural Longer Chain n-Alkanes?

Immobilisation of Platinum by Cupriavidus metallidurans

<strong>C<sub>14</sub>-<sub>22</sub> n-alkanes in Soil from the Freetown Layered Intrusion, Sierra Leone: Products of Pt Catalytic Breakdown of Natural Longer Chain n-alkanes?</strong>

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