Peer-reviewed Journal Articles

12. Nutrient and Silicon Isotope Dynamics in the Laptev Sea and Implications for Nutrient Availability in the Transpolar Drift

Laukert G. , Grasse, P. , Novikhin A., Povazhni V., Doering, K. , Hölemann J. , Janout M., Bauch D. , Kassens H. and M. Frank
2022. Global Biogeochemical Cycles 36, e2022GB007316.

Key findings: The ẟ30Si of dissolved silicic acid in the Laptev Sea indicates the main contribution of DSi from the Lena River during winter. Enhanced DSi utilization in the Laptev Sea will lead to a reduced diatom-dominated primary productivity in the Transpolar Drift.

Contribution: Training and execution of silicon isotope measurements and manuscript writing

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11. Controls on the Silicon Isotope Composition of Diatoms in the Peruvian Upwelling.

Grasse, P. , Haynert, K., Doering, K. , Geilert, S. , Jones, J.L., Brzezinski, M.A. and M. Frank
2021. Frontiers Mar Sci 8, 697400.

Key findings: The ẟ30Si of dissolved silicic acid and biogenic silica and the diatom assemblage from the water column are compared to ẟ30Si of diatoms recorded in the sediments, highlighting that diatom assemblages need to be considered for reconstructing past DSi utilization due to differences in fractionation among taxa.

Contribution: data of silicon isotopes of diatoms, participation on cruise M90 for water sampling, interpretation, and manuscript writing

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10. Silicon Isotope Signatures of Radiolaria Reveal Taxon-Specific Differences in Isotope Fractionation.

Doering, K. , Ehlert, C. , Pahnke, K.. , Frank, M. , Schneider, R. and P. Grasse
2021. Frontiers Mar Sci 8, 666896

Key findings: Measurements of the first taxon-specific stable silicon isotopes of radiolaria reveal that taxa and orders fractionate silicon differently, thus changes in taxonomy need to be considered for interpretations of past records.

Contribution: Principal investigator, planned and conducted the project, analysis of silicon isotopes of radiolaria, data interpretation, and manuscript design and writing.

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9. Factors controlling plankton community production, export flux, and particulate matter stoichiometry in the coastal upwelling system off Peru

Bach, L. T. , Paul, A. J. , Boxhammer, T. , von der Esch, E., Graco, M. , Schulz, K. G. , Achterberg, E. , Aguayo, P., Arístegui, J., Ayón, P. , Baños, I., Bernales, A., Boegeholz, A. S., Chavez, F., Chavez, G., Chen, S.-M., Doering, K. , Filella, A., Fischer, M., Grasse, P. , Haunost, M., Hennke, J., Hernández-Hernández, N. , Hopwood, M. , Igarza, M., Kalter, V., Kittu, L., Kohnert, P., Ledesma, J., Lieberum, C., Lischka, S., Löscher, C. , Ludwig, A., Mendoza, U., Meyer, J., Meyer, J., Minutolo, F. , Ortiz Cortes, J., Piiparinen, J., Sforna, C., Spilling, K., Sanchez, S., Spisla, C., Sswat, M. , Zavala Moreira, M., and U. Riebesell .
2020. F Biogeosciences, 17, 4831–4852.

Key findings: Within a mesocosm experiment of Peru the temporal development of organic matter, export and stoichiometry were investigated after injection of different subsurface waters. While most fluxes remained surprisingly constant a community shift from diatoms to dinoflagellates was observed with the exhaustion of inorganic nitrate in the surface layer.

Contribution: Participation and conduction of the experiment, water sampling and manuscript writing

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8. Impact of ambient conditions on the Si isotope fractionation in marine pore fluids during early diagenesis

Geilert, S. , Grasse, P. , Doering, K. , Wallmann, K., Ehlert, C. , Scholz, F., Frank, M. , Schmidt, M., and C. Hensen.
2020., Biogeosciences, 17, 1745–1763.

Key findings: The ẟ30Si signatures of pore fluids from the Guaymas Basin, which is characterized by high silica accumulation, hydrothermal activity, oxic and anoxic conditions, were evaluated together with a reactive transport model. Results indicate the main control of silica dissolution and Si precipitation, but high variability and markedly different ẟ30Si of pore fluids especially in contrast to other anoxic regions (Peru).

Contribution: Data analyses of silicon isotope compositions of diatoms, manuscript writing.

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7. Dissolved silicon isotope dynamics in large river estuaries

Zhang, Z. , Cao, Z., Grasse, P. , Dai, M., Gao, L., Kuhnert, H., Gledhill, M. , Chiessi, C.M., Doering, K. and M. Frank .
2020. Geochimica et Cosmochimica Acta, 273, 367-382.

Key findings: Silicon isotope compositions of dissolved silicic acid from three of the world’s largest rivers reflect conservative water mass mixing, increased signatures due to enhanced utilization and seasonal variability due to changes in water residence time. These dynamic processes need to be considered when constraining the oceanic Si cycle.

Contribution: Training, support with the silicon isotope measurements and machine set-up, manuscript writing.

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6. Latitudinal variations of ẟ30Si and ẟ15N signatures along the Peruvian shelf: quantifying the effects of nutrient utilization versus denitrification over the past 600 years

Doering, K. , Ehlert, C. , Martinez, P., Frank, M. and R. Schneider .
2019. Biogeosciences (BG), 16 (10). pp. 2163-2180.

Key findings: A novel approach of combined nitrogen and silicon isotope compositions extracted from sediment records supports its application to trace and disentangle changes in source water signatures, utilization of nutrients and the uptake ratio of nutrients by phytoplankton in the past.

Contribution: Principal investigator, conducted isotope analyses and writing of the manuscript.

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5. Changes in diatom productivity and upwelling intensity off Peru since the Last Glacial Maximum: Response to basin‐scale atmospheric and oceanic forcing

Doering, K. , Ehlert, C. , Martinez, P., Frank, M. and R. Schneider .
2019. Biogeosciences (BG), 16 (10). pp. 2163-2180.

Key findings: The combination of silicon isotope compositions of diatoms, biogenic opal, and organic carbon from four sediment records of Peru records intensification and movement of the upwelling to its modern position over the Holocene from a more Northern Position during the deglaciation. In a novel approach, the silicon isotope compositions of different diatom species have been applied to reconstruct the change in upwelling intensity.

Contribution: Principal investigator, conducted isotope analyses and writing of the manuscript.

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4. Stable silicon isotope signatures of marine pore waters – biogenic opal dissolution versus authigenic clay mineral formation

Ehlert C. , Doering K. , Wallmann K., Scholz F., Sommer S., Grasse P. , Geilert S. and M. Frank
2016. Geochimica et Cosmochimica Acta 191, 102-117.

Key findings: Dissolved silicon isotope compositions of pore waters have been investigated for the first time of short sediment cores from the Peruvian margin. Together with a numerical transport-reaction model, the data indicates that about 24% of dissolved biogenic opal is re-precipitated in the sediments in the form of authigenic alumino-silicate phases.

Contribution: Data analyses of ẟ30Si of diatoms, manuscript writing.

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3. Differences between mono-generic and mixed diatom silicon isotope compositions trace present and past nutrient utilisation off Peru

Doering, K. , Ehlert, C. , Grasse, P. , Crosta, X., Fleury, S. , Frank, M. and R. Schneider
2016. Geochimica et Cosmochimica Acta 177, 30–47.

Key findings: Differences in ẟ30Si of small mixed and a large single diatom species reflect different stages of succession during upwelling and can be used together to reconstruct the intensity of upwelling from sediment records off Peru.

Contribution: Principal investigator, conducted isotope analyses and writing of the manuscript.

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2. Sea surface and subsurface circulation dynamics off equatorial Peru during the last ~17 kyr

Nürnberg, D., Böschen, T., Doering, K. , Mollier-Vogel, E., Raddatz, J. and R. Schneider .
2015 Paleoceanography, 30 (7). pp. 984-999.

Key findings: Sea surface temperature proxies capture the evolving seasonal difference in the Gulf of Guayaquil, with more prominent Cold Coastal Water and coastal upwelling of Peru since 4000 years ago and a growing influence of Equatorial subsurface waters since 10.000 years ago.

Contribution: Data analyses (from Diploma thesis), manuscript writing.

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1. The silicon isotope composition of Ethmodiscus rex – laminated diatom mats from the tropical West Pacific: Implications for silicate cycling during the Last Glacial Maximum.

Xiong, Z. , Li, T., Algeo, T. , Doering, K. , Frank, M. , Brzezinski, M. A. , Chang, F. , Opfergelt, S. , Crosta, X. , Jiang, F., Wan, S. and B. Zhai
2015 Paleoceanography, 30 (7). pp. 803-823.

Key findings: The cause of massive blooms of E. rex during the Last Glacial Maximum was investigated based on ẟ30Si and a binary mixing model (upwelled silicate vs eolian silicate) revealing that E. rex did not always use a buoyancy strategy to obtain nutrients from the deep nutrient pool.

Contribution: Data analyses, manuscript writing.

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