|Appears in Collections:||Biological and Environmental Sciences Journal Articles|
|Peer Review Status:||Refereed|
|Title:||Nickel partitioning in biogenic and abiogenic ferrihydrite: the influence of silica and implications for ancient environments|
Martinez, Raul E
Robbins, Leslie J
Konhauser, Kurt O
|Citation:||Eickhoff M, Obst M, Schröder C, Hitchcock A, Tyliszczak T, Martinez RE, Robbins LJ, Konhauser KO & Kappler A (2014) Nickel partitioning in biogenic and abiogenic ferrihydrite: the influence of silica and implications for ancient environments, Geochimica et Cosmochimica Acta, 140, pp. 65-79.|
|Abstract:||Fe(III) (oxyhydr)oxides are ubiquitous in modern soils and sediments, and their large surface area leads to scavenging of trace elements. Experimental trace element partitioning between Fe(III) (oxyhydr)oxides and aqueous solutions have been used to elucidate the geochemical composition of the Precambrian oceans based on the trace element concentrations in Precambrian banded iron formations (BIFs). However, previous partitioning experiments did not consider the potential influence of microbially-derived organic material, even though it is widely believed that bacterial phytoplankton was involved in Fe(II) oxidation and the deposition of BIF primary minerals. Therefore, the present study focuses on sorption of Ni to, and co-precipitation of Ni with, both biogenic ferrihydrite (Fe(OH)3) precipitated by the freshwater photoferrotroph Rhodobacter ferrooxidans SW2 and the marine photoferrotroph Rhodovulum iodosum, as well as chemically synthesized ferrihydrite. We considered the influence of cellular organic material, medium composition and the availability of dissolved silica. Our results show a preferential association of Ni with ferrihydrite, and not with the microbial cells or extracellular organic substances. We found that the addition of silica (2 mM) did not influence Ni partitioning but led to the encrustation of some cells with ferrihydrite and amorphous silica. The two- to threefold lower Ni/Fe ratio in biogenic as compared to abiogenic ferrihydrite is probably due to a competition between Ni and organic matter for sorption sites on the mineral surface. Additionally, the competition of ions present at high concentrations in marine medium for sorption sites led to decreased Ni sorption or co-precipitation. Based on our data we conclude that, if the Fe(III) minerals deposited in BIFs were – at least to some extent – biological, then the Ni concentrations in the early ocean would have been higher than previously suggested. This study shows the importance of considering the presence of microbial biomass and seawater ions in paleomarine reconstructions.|
|Rights:||Published in Geochimica et Cosmochimica Acta by Elsevier; Elsevier believes that individual authors should be able to distribute their accepted author manuscripts for their personal voluntary needs and interests, e.g. posting to their websites or their institution’s repository, e-mailing to colleagues. The Elsevier Policy is as follows: Authors retain the right to use the accepted author manuscript for personal use, internal institutional use and for permitted scholarly posting provided that these are not for purposes of commercial use or systematic distribution. An "accepted author manuscript" is the author’s version of the manuscript of an article that has been accepted for publication and which may include any author-incorporated changes suggested through the processes of submission processing, peer review, and editor-author communications.|
|Geochimica et Cosmochimica Acta 2014b.pdf||1.55 MB||Adobe PDF||View/Open|
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