Biomethylation of thallium by bacteria and first determination of biogenic dimethylthallium in the ocean

Schedlbauer, Oliver F.; Heumann, Klaus G.

doi:10.1002/(sici)1099-0739(200006)14:6<330::aid-aoc994>3.0.co;2-y

Cited by 55 publications

(19 citation statements)

References 19 publications

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“…The highest Tl content in the marine biosphere is reported for phytoplankton, with contents ranging from 0.02 to 0.8 mg g À1 [Flegal et al, 1986]. These findings correspond with recent measurements indicating that Tl is involved in biological processes [Schedlbauer and Heumann, 2000]. The mean content determined for the Namibian diatom ooze is three-fold higher than the maximum content of marine phytoplankton.…”

Section: Elements With Low Crustalsupporting

confidence: 87%

Geochemical signatures of the Namibian diatom belt: Perennial upwelling and intermittent anoxia

Borchers

Schnetger

Böning

et al. 2005

Geochem Geophys Geosyst

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[1] A gravity core from the Nambian diatom belt (83 m water depth) was analyzed for major (Al, Ca, Fe, K, Mg, P, Si, Ti) and minor elements (Ag, As, Ba, Bi, Cd, Co, Cr, Cu, Mn, Mo, Ni, Rb, Re, Se, Sr, Tl, U, V, Zn, Zr), as well as C and S. The major element geochemistry is dominated by the contribution of biogenic phases (opal and minor amounts of carbonate and phosphate), whereas terrigenous components of eolian and fluvial origin form only a minor admixture of <15%. Examination of the Fe/S/C-relationship reveals a completion of pyritization close to the sediment-seawater interface. Higher than average shale Fe/Al ratios reflect the presence of highly reactive iron oxides in terrigenous source material from the Namibian desert and suggest little loss of Fe within the OMZ. The low total Fe content likely represents an important factor responsible for sporadic H 2 S eruptions. The upwelling system off Namibia may be regarded as an intermediate system, combining high productivity typical for upwelling areas with the sporadic presence of H 2 S in the water column. By examining the source-sink relationship of individual trace metals, two different trends are discernible: Mo, Re, and U accumulate following seawater availability, whereas Ag, Cd, Cu, Ni, Tl, and Zn require a biological preconcentration step. Trace metals like As, Ba, Cr, Se, and V show an intermediate behavior. Metal enrichment is favored by high interstitial water sulfide concentrations close to the sediment-seawater interface, leading to slightly elevated Co contents as opposed to extremely low Mn/Al ratios, reflecting the overall reducing character of the Namibian system. Maximum contents of Cu, Ni, and Zn are significantly lower than those reported previously. This may in part be related to the absence of fecal material and a stronger dilution by biosiliceous material at this location compared to the seaward flank of the diatom belt.

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Section: Elements With Low Crustalsupporting

confidence: 87%

Geochemical signatures of the Namibian diatom belt: Perennial upwelling and intermittent anoxia

Borchers

Schnetger

Böning

et al. 2005

Geochem Geophys Geosyst

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“…Here we explore the burial of thallium and the isotopic signature in euxinic basins as an additional output flux as it has been suggested that Tl is associated with pyrite burial (Heinrichs et al, 1980;Nielsen et al, 2011b) and the suboxic sink seems to be minimal with ε 205 Tl values close 0 (Nielsen et al, 2011b). In addition, there has been a study that suggest enrichments of Tl in surface ocean bacteria (Schedlbauer and Heumann, 2000) and several studies that are suggestive of enhanced burial of Tl in reducing organic rich sediments (Böning et al, 2009;Böning et al, 2017;Borchers et al, 2005) though the isotopic signatures are still unknown.…”

Section: Thallium Isotope Backgroundmentioning

confidence: 99%

Thallium-isotopic compositions of euxinic sediments as a proxy for global manganese-oxide burial

Owens

Nielsen

Horner

et al. 2017

Geochimica et Cosmochimica Acta

101

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Thallium (Tl) isotopes are a new and potentially powerful paleoredox proxy that may track bottom water oxygen conditions based on the global burial flux of manganese oxides. Thallium has a residence time of ~20 thousand years, which is longer than the ocean mixing time, and it has been inferred that modern oxic seawater is conservative with respect to both concentration and isotopes. Marine sources of Tl have nearly identical isotopic values. Therefore, the Tl sinks, adsorption onto manganese oxides and low temperature oceanic crust alteration (the dominant seawater output), are the primary controls of the seawater isotopic composition. For relatively short-term, ~million years, redox events it is reasonable to assume that the dominant mechanism that alters the Tl isotopic composition of seawater is associated with manganese oxide burial because large variability in low temperature ocean crust alteration is controlled by long-term, multi-million years, average ocean crust production rates. This study presents new Tl isotope data for an open ocean transect in the South Atlantic, and depth transects for two euxinic basins (anoxic and free sulfide in the water column), the Cariaco Basin and Black Sea. The Tl isotopic signature of open ocean seawater in the South Atlantic was found to be homogeneous with ε 205 Tl =-6.0 ± 0.3 (± 2 SD, n = 41) while oxic waters from Cariaco and the Black Sea are-5.6 and-2.2, respectively. Combined with existing data from the Pacific and Arctic Oceans, our Atlantic data establish the conservatism of Tl isotopes in the global ocean. In contrast, partially-and predominantly-restricted basins reveal Tl isotope differences that vary between open-ocean (-6) and continental material (-2) ε 205 Tl, scaling with the degree of restriction. Regardless of the differences between basins, Tl is quantitatively removed from their euxinic waters below the chemocline. The burial of Tl in euxinic sediments is estimated to be an order of magnitude less than each of the modern ocean outputs and imparts no isotopic fractionation. Thallium removal into pyrite appears to be associated with a small negative fractionation between-1 and-3 ε 205 Tl, which renders Tl-depleted waters below the chemocline enriched in isotopically-heavy Tl. Due to the quantitative removal of Tl from euxinic seawater, Tl isotope analyses of the authigenic fraction of underlying euxinic sediments from both the Black Sea and Cariaco Basin capture the Tl isotope value of the oxic portion of their respective water column with no net isotope fractionation. Since the Tl isotope composition of seawater is largely dictated by the relative fraction of Mn-oxide burial versus oceanic crust alteration, we contend that the Tl isotope composition of authigenic Tl in black shales, deposited under euxinic conditions but well-connected to the open ocean, can be utilized to reconstruct the Tl isotope composition of seawater, and thus to reconstruct the global history of Mn-oxide burial.

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“…The profile of the methylated species correlated with chlorophyll a in the upper waters, suggesting its microbial production. These authors also found methylation to occur in an anaerobic lake sediment [92]. There is no evidence for methylated In and Ga complexes in the environment.…”

Section: The Biotic Formation Of Other Methylated Compoundsmentioning

confidence: 95%

“…This process occurs under anaerobic conditions with little evidence of aerobic methylation [82]. None of these compounds are highly stable but there is some initial evidence for the presence of these compounds at low pM concentrations in the Atlantic Ocean, mostly as (CH 3 ) 2 Tl + [92], and ranging up to nearly 50% of the total Tl, and present throughout the water column. The profile of the methylated species correlated with chlorophyll a in the upper waters, suggesting its microbial production.…”

Section: The Biotic Formation Of Other Methylated Compoundsmentioning

confidence: 99%

The Methylation of Metals and Metalloids in Aquatic Systems

2012

Methylation - From DNA, RNA and Histones to Diseases and Treatment

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Biomethylation of thallium by bacteria and first determination of biogenic dimethylthallium in the ocean

Cited by 55 publications

References 19 publications

Geochemical signatures of the Namibian diatom belt: Perennial upwelling and intermittent anoxia

Geochemical signatures of the Namibian diatom belt: Perennial upwelling and intermittent anoxia

Thallium-isotopic compositions of euxinic sediments as a proxy for global manganese-oxide burial

The Methylation of Metals and Metalloids in Aquatic Systems

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