Barite formation in the Southern Ocean water column

Stroobants, N.; Dehairs, Frank; Goeyens, Léo; Vanderheijden, N.; Grieken, R. Van

doi:10.1016/s0304-4203(09)90033-0

Cited by 118 publications

(84 citation statements)

References 15 publications

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“…As these aggregates are broken down, the enclosed µm-sized BaSO 4 crystals are released into seawater, leading to the characteristic maximum in particulate Ba abundances between 200 − 600 m (e.g. Bishop, 1988;Stroobants et al, 1991;Jacquet et al, 2005). In contrast, radiumisotopic analyses of sinking particulates from the Sargasso Sea indicate that BaSO 4 formation occurs continually with depth to 3, 200 m, or that BaSO 4 pumping to depth is extremely rapid (Van Beek et al, 2007).…”

Section: Clues To the Depth Range Of Barite Cyclingmentioning

confidence: 99%

Barium-isotopic fractionation in seawater mediated by barite cycling and oceanic circulation

Horner

Kinsley

Nielsen

2015

Earth and Planetary Science Letters

138

253

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Highlights• First full seawater depth profile of co-located [Ba]-δ 138/134 Ba NIST• Origin of Ba-isotopic variations are best explained by barite cycling• Regional circulation strongly influences depth structure of δ 138/134 Ba NIST• Data establish a baseline of Ba-isotopic variability in the marine realm Keywords: barium; isotopic fractionation; barite; seawater; biogeochemistry AbstractThe marine biogeochemical cycle of Ba is thought to be controlled by particulate BaSO 4 (barite) precipitation associated with the microbial oxidation of organic carbon and its subsequent dissolution in the BaSO 4 -undersaturated water column. Despite many of these processes being largely unique to Ba cycling, concentrations of Ba and Si in seawater exhibit a strong linear correlation. The reasons for this correlation are ambiguous, as are the depth ranges corresponding to the most active BaSO 4 cycling and the intermediate sources of Ba to particulate BaSO 4 . Stable isotopic analyses of dissolved Ba in seawater should help address these issues, as Ba-isotopic compositions are predicted to be sensitive to the physical and biogeochemical process that cycle Ba. We report a new methodology for the determination of dissolved Ba-isotopic compositions in seawater and results from a 4, 500 m depth profile in the South Atlantic at 39.99 • S, 0.92 • E that exhibit oceanographically-consistent variation with depth. These data reveal that water masses obtain their [Ba] and Ba-isotopic signatures when at or near the surface, which relates to the cycling of marine BaSO 4 . The shallow origin of these signatures requires that the substantial Ba-isotopic variations in the bathypelagic zone were inherited from when those deep waters were last ventilated. Indeed, the water column below 600 m is well explained by conservative mixing of water masses with distinct [Ba] and Ba-isotopic compositions. This leads us to conclude that large scale oceanic circulation is important for sustaining the similar oceanographic distributions of Ba and Si in the South Atlantic, and possibly elsewhere. These data demonstrate that the processes of organic carbon oxidation, BaSO 4 cycling, and Ba-isotopic fractionation in seawater are closely coupled, such that Ba-isotopic analyses harbor great potential as a tracer of the carbon cycle in the modern and paleo-oceans.

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Section: Clues To the Depth Range Of Barite Cyclingmentioning

confidence: 99%

Barium-isotopic fractionation in seawater mediated by barite cycling and oceanic circulation

Horner

Kinsley

Nielsen

2015

Earth and Planetary Science Letters

138

253

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“…The complete whole water column data set is given in Appendix A. From previous studies we know that Ba xs in surface waters is distributed over different, mainly non-barite biogenic phases (see Stroobants et al, 1991;Jacquet et al, 2007;Cardinal et al, 2005;Sternberg et al, 2005). As such, these do not reflect POC remineralization processes, in contrast to mesopelagic waters where Ba xs is mainly composed of barite (Dehairs et al, 1980) degradation of sinking POC (Martin et al, 1987;Sarmiento et al, 1993;Buesseler et al, 2007b (Jacquet et al, 2008a).…”

Section: Particulate Biogenic Ba Xs Profilesmentioning

confidence: 99%

“…Here, C remineralization was assessed from particulate biogenic Ba (hereafter called excess Ba or Ba xs ; mainly forms as barite BaSO 4 crystals) contents in the mesopelagic water column. The link between barite and C remineralization depends on the fact that this mineral precipitates in oversaturated micro-environments (biogenic aggregates) during the process of prokaryotic degradation of sinking POC (Dehairs et al, 1980(Dehairs et al, , 1992(Dehairs et al, , 1997Stroobants et al, 1991, Cardinal et al, 2001Jacquet et al, 2007Jacquet et al, , 2008bJacquet et al, , 2011aPlanchon et al, 2013;Sternberg et al, 2007Sternberg et al, , 2008aSternberg et al, , 2008b. Once the aggregates have been remineralized, barites are released and spread through the mesopelagic layer.…”

Section: Introductionmentioning

confidence: 99%

Early spring mesopelagic carbon remineralization and transfer efficiency in the naturally iron-fertilized Kerguelen area

et al. 2015

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Abstract. We report on the zonal variability of mesopelagic particulate organic carbon remineralization and deep carbon transfer potential during the Kerguelen Ocean and Plateau compared Study 2 expedition (KEOPS 2; OctoberNovember 2011) in an area of the polar front supporting recurrent massive blooms from natural Fe fertilization. Mesopelagic carbon remineralization (MR) was assessed using the excess, non-lithogenic particulate barium (Ba xs ) inventories in mesopelagic waters and compared with bacterial production (BP), surface primary production (PP) and export production (EP). Results for this early season study are compared with the results obtained during a previous study (2005; KEOPS 1) for the same area at a later stage of the phytoplankton bloom. Our results reveal the patchiness of the seasonal advancement and of the establishment of remineralization processes between the plateau (A3) and polar front sites during KEOPS 2. For the Kerguelen plateau (A3 site) we observe a similar functioning of the mesopelagic ecosystem during both seasons (spring and summer), with low and rather stable remineralization fluxes in the mesopelagic column (150-400 m). The shallow water column (∼ 500 m), the lateral advection, the zooplankton grazing pressure and the pulsed nature of the particulate organic carbon (POC) transfer at A3 seem to drive the extent of MR processes on the plateau. For deeper stations (> 2000 m) located on the margin, inside a polar front meander, as well as in the vicinity of the polar front, east of Kerguelen, remineralization in the upper 400 m in general represents a larger part of surface carbon export. However, when considering the upper 800 m, in some cases, the entire flux of exported carbon is remineralized. In the polar front meander, where successive stations form a time series, two successive events of particle transfer were evidenced by remineralization rates: a first mesopelagic and deep transfer from a past bloom before the cruise, and a second transfer expanding at mesopelagic layers during the cruise. Regarding the deep carbon transfer efficiency, it appeared that above the plateau (A3 site) the mesopelagic remineralization was not a major barrier to the transfer of organic matter to the seafloor (close to 500 m). There, the efficiency of carbon transfer to the bottom waters (> 400 m) as assessed by PP, EP and MR fluxes comparisons reached up to 87 % of the carbon exported from the upper 150 m. In contrast, at the deeper locations, mesopelagic remineralization clearly limited the transfer of carbon to depths of > 400 m. For sites at the margin of the plateau (station E-4W) and the polar front (station F-L), mesopelagic remineralization even exceeded Published by Copernicus Publications on behalf of the European Geosciences Union. S. H. M. Jacquet et al.: Early season mesopelagic carbon remineralizationupper 150 m export, resulting in a zero transfer efficiency to depths > 800 m. In the polar front meander (time series), the capacity of the meander to transfer carbon to depth > 800 ...

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“…Since the world's oceans were found to be mostly undersaturated with respect to barite (Church and Wolgemuth, 1972; see also Monnin et al, 1999;Rushdi et al, 2001;Monnin and Cividini, 2006), it was proposed that barite precipitation takes place in the upper water column within supersaturated microenvironments (Chow and Goldberg, 1960). Such microenvironments could result from the decay of organic matter exported from the euphotic layer (Dehairs et al, 1980;Bishop, 1988;Stroobants et al, 1991;Dehairs et al, 1990;Dehairs et al, 1991;Dehairs et al, 1992;Ganeshram et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

228Ra/226Ra and 226Ra/Ba ratios in the Western Mediterranean Sea: Barite formation and transport in the water column

Beek

Sternberg²,

Reyss³

et al. 2009

Geochimica et Cosmochimica Acta

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Barite formation in the Southern Ocean water column

Cited by 118 publications

References 15 publications

Barium-isotopic fractionation in seawater mediated by barite cycling and oceanic circulation

Barium-isotopic fractionation in seawater mediated by barite cycling and oceanic circulation

Early spring mesopelagic carbon remineralization and transfer efficiency in the naturally iron-fertilized Kerguelen area

228Ra/226Ra and 226Ra/Ba ratios in the Western Mediterranean Sea: Barite formation and transport in the water column

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