Validation of accumulation rates in Teluk Banten (Indonesia) from commonly applied 210Pb models, using the 1883 Krakatau tephra as time marker

Boer, Wim; Bergh, Gerrit D. van den; Haas, H. de; Stigter, Henko de; Gieles, R.; Weering, Tj.C.E. van

doi:10.1016/j.margeo.2005.12.002

Cited by 74 publications

(33 citation statements)

References 29 publications

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“…2). The 210 Pb activity in 100 mg dry weight of sample was measured at the Royal NIOZ by α-spectrometry of its granddaughter 210 Po, which was precipitated on silver after digestion of the sample in an acid solution (Boer et al, 2006). 14 C-AMS dating was performed on carbonate from hand-picked planktonic foraminiferal tests from three samples in the core from station 4 (top, middle and bottom).…”

Section: Pb and 14 C Analysesmentioning

confidence: 99%

Sedimentary phosphorus and iron cycling in and below the oxygen minimum zone of the northern Arabian Sea

et al. 2012

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Abstract. In this study, we investigate phosphorus (P) and iron (Fe) cycling in sediments along a depth transect from within to well below the oxygen minimum zone (OMZ) in the northern Arabian Sea (Murray Ridge). Pore-water and solid-phase analyses show that authigenic formation of calcium phosphate minerals (Ca-P) is largely restricted to where the OMZ intersects the seafloor topography, likely due to higher depositional fluxes of reactive P. Nonetheless, increased ratios of organic carbon to organic P (C org /P org ) and to total reactive P (C org /P reactive ) in surface sediments indicate that the overall burial efficiency of P relative to C org decreases under the low bottom water oxygen concentrations (BWO) in the OMZ. The relatively constant Fe/Al ratio in surface sediments along the depth transect suggest that corresponding changes in Fe burial are limited. Sedimentary pyrite contents are low throughout the ∼25 cm sediment cores at most stations, as commonly observed in the Arabian Sea OMZ. However, pyrite is an important sink for reactive Fe at one station in the OMZ. A reactive transport model (RTM) was applied to quantitatively investigate P and Fe diagenesis at an intermediate station at the lower boundary of the OMZ (bottom water O 2 : ∼ 14 µmol L −1 ). The RTM results contrast with earlier findings in showing that Fe redox cycling can control authigenic apatite formation and P burial in Arabian Sea sediment. In addition, results suggest that a large fraction of the sedimentary Ca-P is not authigenic, but is instead deposited from the water column and buried. Dust is likely a major source of this Ca-P. Inclusion of the unreactive Ca-P pool in the C org /P ratio leads to an overestimation of the burial efficiency of reactive P relative to C org along the depth transect. Moreover, the unreactive Ca-P accounts for ∼85 % of total Ca-P burial. In general, our results reveal large differences in P and Fe chemistry between stations in the OMZ, indicating dynamic sedimentary conditions under these oxygen-depleted waters.

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Section: Pb and 14 C Analysesmentioning

confidence: 99%

Sedimentary phosphorus and iron cycling in and below the oxygen minimum zone of the northern Arabian Sea

et al. 2012

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“…This would imply that the accessibility of the DIP pool (which is greater due to its shoaling during intervals of maximum hypoxic area) Time series of C org and P org accumulation rates, and C org /P org , at sites LF1, LF1.5 and LF3 on the margins of the Fårö Deep in the central Baltic, and relevant water column oxygen data. C org and P org accumulation rates were calculated from 210 Pb-derived mass accumulation rates (estimated using a Constant Rate of 210 Pb Supply (CRS) model (Boer et al, 2006) and C org and P org contents). Total hypoxic area data from Conley et al (2009) and water column oxygen concentrations at site F80 from the Baltic Sea Environmental Database at Stockholm University are plotted as 5 year binned mean values.…”

Section: Wider Implications For P-driven Eutrophication/ Hypoxia Feedmentioning

confidence: 99%

Beyond the Fe-P-redox connection: preferential regeneration of phosphorus from organic matter as a key control on Baltic Sea nutrient cycles

et al. 2011

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Abstract. Patterns of regeneration and burial of phosphorus (P) in the Baltic Sea are strongly dependent on redox conditions. Redox varies spatially along water depth gradients and temporally in response to the seasonal cycle and multidecadal hydrographic variability. Alongside the welldocumented link between iron oxyhydroxide dissolution and release of P from Baltic Sea sediments, we show that preferential remineralization of P with respect to carbon (C) and nitrogen (N) during degradation of organic matter plays a key role in determining the surplus of bioavailable P in the water column. Preferential remineralization of P takes place both in the water column and upper sediments and its rate is shown to be redox-dependent, increasing as reducing conditions become more severe at greater water-depth in the deep basins. Existing Redfield-based biogeochemical models of the Baltic may therefore underestimate the imbalance between N and P availability for primary production, and hence the vulnerability of the Baltic to sustained eutrophication via the fixation of atmospheric N. However, burial of organic P is also shown to increase during multidecadal intervals of expanded hypoxia, due to higher net burial rates of organic matter around the margins of the deep basins. Such intervals may be characterized by basin-scale acceleration of all fluxes within the P cycle, including productivity, regeneration and burial, sustained by the relative accessibility of the water column P pool beneath a shallow halocline.

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“…A simple constant flux constant sedimentation (CF-CS) model (Appleby and Oldfield (1978) provided maximum or apparent sedimentation rates for excess 210 Pb profiles. Diffusive mixing rates were obtained using 210 Pb mixing models (Boer et al, 2006).…”

Section: Radionuclide Analysismentioning

confidence: 99%

Record of anthropogenic impact on the Western Irish Sea mud belt

et al. 2015

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This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Record of Anthropogenic Impact on the Western Irish Sea Mud Belt Highlights We investigate 5 cores from the Irish Sea using a multi-proxy approach  We assess multibeam echosounder and backscatter data from the same area  We analyse these cores for anthropogenic radionuclides using gamma spectrometry  Downcore radionuclide activity was related to known output levels from Sellafield  The impact of trawling was found to result in significant amounts of sediment loss

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Validation of accumulation rates in Teluk Banten (Indonesia) from commonly applied 210Pb models, using the 1883 Krakatau tephra as time marker

Cited by 74 publications

References 29 publications

Sedimentary phosphorus and iron cycling in and below the oxygen minimum zone of the northern Arabian Sea

Sedimentary phosphorus and iron cycling in and below the oxygen minimum zone of the northern Arabian Sea

Beyond the Fe-P-redox connection: preferential regeneration of phosphorus from organic matter as a key control on Baltic Sea nutrient cycles

Record of anthropogenic impact on the Western Irish Sea mud belt

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