Iron isotope variations in Holocene sediments of the Gotland Deep, Baltic Sea

Fehr, Manuela A.; Andersson, Per; Hålenius, Ulf; Mörth, Carl‐Magnus

doi:10.1016/j.gca.2007.11.033

Cited by 74 publications

(43 citation statements)

References 90 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This could explain the elevated Fe/Al content in the Littorina Sea sediments (0.70) relative to the detrital background of 0.6-0.65 (Fehr et al, 2008) (Fig. 2).…”

Section: The Importance Of the Fe Shelf-to-basin Shuttle For Vivianitmentioning

confidence: 97%

Vivianite is a key sink for phosphorus in sediments of the Landsort Deep, an intermittently anoxic deep basin in the Baltic Sea

2016

View full text Add to dashboard Cite

a b s t r a c t Phosphorus (P) is an essential nutrient for marine organisms. Its burial in hypoxic and anoxic marine basins is still incompletely understood. Recent studies suggest that P can be sequestered in sediments of such basins as reduced iron (Fe)-P but the exact phase and the underlying mechanisms that lead to its formation are unknown. In this study, we investigated sediments from the deepest basin in the Baltic Sea, the Landsort Deep (site M0063), that were retrieved during the Integrated Ocean Drilling Project (IODP) Baltic Sea Paleoenvironment Expedition 347. The record comprises the whole brackish/marine Littorina Sea stage including past intervals of extensive hypoxia in the Baltic Sea that occurred during the Holocene Thermal Maximum (HTM HI ) and the Medieval Climate Anomaly (MCA1 HI and MCA2 HI ). Various redox proxies (e.g. the presence of laminations and high Mo contents) suggest almost permanent bottom water hypoxia during the Littorina Sea stage in the Landsort Deep. The bottom waters were likely even seasonally anoxic or sulfidic during the MCA1 HI and MCA2 HI , and permanently sulfidic during the HTM HI . With the use of micro-analysis of sieved minerals (SEM-EDS, XRD and synchrotron-based XAS), we show that Mn-and Mgrich vivianite crystals are present at various depths in the Littorina Sea sediments. We also have indications for vivianite in the MCA1 HI , MCA2 HI and HTM HI deposits. The formation of vivianite thus likely explains the high Febound P fraction throughout the whole Littorina Sea stage. Shuttling of Fe and Mn from the shelves into the basin and high inputs of P in settling organic matter are likely key drivers for vivianite formation. Our study shows that vivianite can likely form in near-surface sediments under a broad range of bottom water redox conditions, varying from hypoxic and anoxic to sulfidic.

show abstract

“…This could explain the elevated Fe/Al content in the Littorina Sea sediments (0.70) relative to the detrital background of 0.6-0.65 (Fehr et al, 2008) (Fig. 2).…”

Section: The Importance Of the Fe Shelf-to-basin Shuttle For Vivianitmentioning

confidence: 97%

Vivianite is a key sink for phosphorus in sediments of the Landsort Deep, an intermittently anoxic deep basin in the Baltic Sea

2016

View full text Add to dashboard Cite

show abstract

“…Numerous studies have shown that fueled by a continual supply of organic carbon and reactive Fe 3 þ , dissimilatory iron reduction (DIR) would produce significant quantities of Fe 2 þ aq enriched with the light Fe isotope during the early diagenetic period in marine sediment (Severmann et al, 2006;Rouxel et al, 2008;Johnson et al, 2008;Tangalos et al, 2010). The so called benthic iron flux generally has δ 56 Fe spanning from À 1 to À 3‰, with the lightest compositions near the sediment water boundary (e.g., Beard et al, 1999Beard et al, , 2010Crosby et al, 2007;Johnson et al, 2005;Severmann et al, 2006Severmann et al, , 2008Severmann et al, , 2010Fehr et al, 2008;Homoky et al, 2013). When transported from the shelf to the slope, this isotopically light iron flux will easily enter the inner of chimney wall and precipitate as Fe (oxyhydr)oxide along with the dissolved iron with a δ 56 Fe value of zero, released from the dark mineral weathering.…”

Section: Source Origin and Reactivation Of Fe (Oxyhydr)oxidementioning

confidence: 99%

A unique Fe-rich carbonate chimney associated with cold seeps in the Northern Okinawa Trough, East China Sea

Sun

Wei

Zhang

et al. 2015

Deep Sea Research Part I: Oceanographic Research Papers

View full text Add to dashboard Cite

“…The strong enrichment of Fe in the topsoil of soils influenced by high groundwater tables is a typical feature of Pleistocene sandy fluvial lowlands and has been observed in many corresponding landscapes of Central and Northern Europe, e.g., Belgium (Stoops 1983), Germany (Schlichting 1965), Denmark (Breuning-Madsen et al 2000), and Poland (Kaczorek and Sommer 2003), but Poitrasson et al (2004) for δ 57 Fe, Weyer et al (2005) for δ 56 Fe, and Williams et al (2005) for δ 57 Fe, respectively f In-house salt standard of the ETH Zürich, Switzerland; values in brackets given by Teutsch et al (2009) andFehr et al (2008), respectively also in North America (Crerar et al 1979). Petrogleyic horizons of such soils largely consist of Fe (~200 tõ 500 g kg −1 ) that is predominantly occurring as oxidic Fe, i.e., most of the total Fe can be extracted by Fe d .…”

Section: Field Observationsmentioning

confidence: 99%

Iron oxide mineralogy and stable iron isotope composition in a Gleysol with petrogleyic properties

et al. 2011

View full text Add to dashboard Cite

Purpose Properties of Fe oxides are poorly understood in soils with fluctuating water tables and variable redox conditions. The objective of this research was to (a) characterize the mineralogical composition of Fe oxides and (b) determine the relationship to the stable Fe isotope ratio in a soil with temporally and spatially sharp redox gradients. Materials and methodsThe lowland Gleysol (Petrogleyic) is in Northwest Germany and consists of oximorphic soil horizons (Ah 0-15, Bg 15-35, and CrBg 35-70 cm) developed from Holocene fluvial loam overlaying glaciofluvial sand with reductomorphic properties (2Cr horizon, +70 cm). Field measurements during the course of 28 months included the monitoring of groundwater table, soil redox potential, and analysis of the soil solutions. Solid Fe phases were studied by room temperature and cryogenic 57 Fe Mössbauer spectroscopy, and stable Fe isotope compositions by multiple collector inductively coupled plasma mass spectrometry. Results and discussion The groundwater table ranged from −83 cm below to +8 cm above soil surface (median −27 cm). Permanent reducing conditions occurred in the 2Cr horizon with dissolved Fe concentrations of 44.8 mg L −1 (median). The duration of oxidizing conditions increased in the order CrBg < Bg < Ah. Total Fe increased from 50 (Ah) over 316 (Bg) up to 412 g kg −1 (CrBg) and was lowest in the 2Cr horizon (7 g kg −1 ). Ferrihydrite (51% of total Fe) was dominant over goethite (24%) in the Ah horizon. Conversely, nanogoethite dominated both the Bg (94%) and CrBg (86%) horizons. Iron in siderite amounted to 7% in the CrBg horizon. Iron isotope compositions yielded a range of δ 57 Fe values from +0.29‰ (Ah horizon) to −0.30‰ (Bg horizon). In contrast to the overlying CrBg (δ 57 Fe=−0.19‰) and Bg horizons, the 2Cr horizon is characterized by a relatively high δ 57 Fe value of +0.22‰. Conclusions Lasting water saturation and frequent reducing conditions lead to the enrichment of goethite in subsoil. Once formed, goethite remains stable compared to ferrihydrite because it is less available for microbial mediated reductive dissolution. High δ 57 Fe values in the topsoil primary result from fast ferrihydrite precipitation during aeration immediately after reducing conditions. In contrast,

show abstract

Iron isotope variations in Holocene sediments of the Gotland Deep, Baltic Sea

Cited by 74 publications

References 90 publications

Vivianite is a key sink for phosphorus in sediments of the Landsort Deep, an intermittently anoxic deep basin in the Baltic Sea

Vivianite is a key sink for phosphorus in sediments of the Landsort Deep, an intermittently anoxic deep basin in the Baltic Sea

A unique Fe-rich carbonate chimney associated with cold seeps in the Northern Okinawa Trough, East China Sea

Iron oxide mineralogy and stable iron isotope composition in a Gleysol with petrogleyic properties

Contact Info

Product

Resources

About