Lukas Jonkers	ROYAL NETHERLANDS INSTITUTE FOR SEA RESEARCH   Postal address: P.O. Box 59, NL-1790 AB Den Burg (Texel) The Netherlands   Visiting address: Landsdiep 4 NL-1797 SZ ’t Horntje (Texel) The Netherlands   Phone: (+31) (0)222-369300 Fax: (+31) (0)222-319674
Dept: Marine Geology E-mail @nioz.nl : lukas.jonkers Phone: (+31) (0)222-369343

 

General:     Since September 2005 employed as a PhD-student within the Variability of Atlantic Meridional Overturning Circulation (VAMOC) project. The VAMOC project is within the RAPID programme funded by the Dutch Research Council (NWO-ALW), NERC (UK) and the Norwegian Science Foundation. 2003-2005: MSc Quaternary Geology and Geo-ecology at the Vrije Universiteit Amsterdam. 1999-2003: BSc Earthsciences at the Vrije Universiteit Amsterdam.   Research Interests:     Geology, with main interests in palaeoclimatology and proxy development/evaluation, sedimentology and geochemistry.   Current research:     Main topics of my PhD, under supervision of Geert-Jan Brummer and Maarten Prins: -            Investigate the interplay between IRD input and bottom current variability, by unmixing terrigenous sediments of a core from Reykjanes Ridge. -            Reconstruct (near) sea surface conditions during North Atlantic ice-rafting events using stable isotopes and trace elemental composition of planktonic foraminifera. Assess IRD and ice sources as well as stratification of the upper water column. -            Assess the use of laser diffraction particle sizing in palaeoceanography. Particularly for fine-grained sediments and with a focus on reproducibility for useful grain-size decomposition. -            Explore the influence of seasonal stratification changes and the occurrence of deep convection in the Irminger Sea on fluxes and stable isotope chemistry of planktonic foraminifera by using long-term sediment trap time-series. -            Investigate the genesis of deep North Atlantic drift sediments using the BOBO-lander (seasonality, advection and source reservoir, sorting and resuspension, preservation-diagenesis, burial and mixing, anthropogenic change) on the RAPID 21-12B core site for down-core interpretation of past, climate-related variability in Atlantic meridional overturning.   Bibliography:     Peer-reviewed papers   Accepted or in press:   Jonkers, L., M.A. Prins, G.-J.A. Brummer, M. Konert and B.C.  Lougheed. (2009), Experimental insights into laser diffraction particle sizing of fine-grained sediments for use in palaeoceanography, Sedimentology, doi: 10.1111/j.1365-3091.2009.01076.x [PDF].   Jonkers, L., G.-J.A. Brummer, F. Peeters, H. van Aken and F. de Jong. in press Seasonal stratification, shell fluxes and oxygen isotope dynamics of left-coiling N. pachyderma and T. quinqueloba in the western sub-polar North Atlantic, Paleoceanography, doi:10.1029/2009PA001849.   Jonkers, L., M. Moros, M.A. Prins, T. Dokken, C. Andersson Dahl, N. Dijkstra, K. Perner and G.-J.A. Brummer. in press A reconstruction of sea surface warming in the northern North Atlantic during MIS3 ice-rafting events, Quaternary Science Reviews, doi:10.1016/j.quascirev.2010.03.014.   Submitted:   Jonkers, L., F. Mienis, W. Boer, I.R. Hall and G-J.A. Brummer. Intra-annual variability of extremely rapid sedimentation onto Gardar Drift in the northern North Atlantic.   Jonkers, L., M.A. Prins, G.J. Weltje, A. Ganopolski, S.R. Troelstra and G.-J.A. Brummer. Delayed response of the glacial intermediate circulation to freshwater input in the northern North Atlantic.     Presentations     Jonkers, L., M.A. Prins, M. Moros, T. Dokken and G.-J.A. Brummer. Surface warming and and ice-rafting in North-Atlantic during MIS3, A possible link? Goldschmidt conference 2009, Davos, Switzerland. Poster. Jonkers, L., M.A. Prins, G.-J.A. Brummer and N. Dijkstra. Glacial North Atlantic Millennial Scale Ice-rafting Events and Their Influence on Overflow Speed. Did Sea-ice Play a Role as a Source of IRD and Freshwater? AGU Fall Meeting 2008, San Francisco, USA. Poster. Jonkers, L., G.-J.A. Brummer and F. Peeters. Fluxes and stable isotope dynamics of N. pachyderma (sin.) and T. quinqueloba in the Irminger Sea. AGU Fall Meeting 2008, San Francisco, USA. Poster. Jonkers, L. P.,  M.A. Prins, G.J. Weltje, A. Ganopolski, S. R. Troelstra, N. Dijkstra, G.-J. A. Brummer. Delayed response of the Iceland-Scotland Overflow intensity to glacial freshwater perturbations inferred from decomposed grain-size distributions. 9th International Conference on Paleoceanography, Shanghai, China, 2007. Poster. Jonkers, L. P., M.A. Prins, G.J. Weltje, A. Ganopolski, S. R. Troelstra, N. Dijkstra, G.-J. A. Brummer. Delayed response of the Atlantic Meridional Overturning Circulation to glacial freshwater perturbations. ESF-FWF Conference: Ocean Controls in Abrupt Climate Change, Obergurgl, Austria, 2007. Poster. Jonkers, L., M. Prins, G. J. Weltje, A. Ganopolski, S. Troelstra, N. Dijkstra, G.-J. Brummer. Delayed response of the Atlantic Meridional Overturning Circulation to glacial freshwater perturbations. RAPID Climate Change Annual Meeting, Plymouth, UK, 2007. Poster (winner poster prize). Jonkers, L. P.,  M. A. Prins, G. J. Weltje, A. Ganopolski, S. R. Troelstra, A. Kuipers, G. J. Brummer. Hysteresis response of thermohaline circulation to fresh-water forcing revealed by an unmixed grain-size record from the North Atlantic. EGU meeting 2006, Vienna, Austria. Poster. Jonkers, L.P., M.A. Prins, G.-J. Weltje, A. Ganopolski and G.-J. Brummer. Geological evidence for hysteresis of the Atlantic meridional overturning circulation in response to freshwater forcing. Rapid Climate Change, International Science Conference, Birmingham, UK, 2006. Oral presentation. Jonkers, L.P., M.A. Prins, G.-J. Weltje, A. Ganopolski, S. Troelstra, A. Kuipers & G.-J. Brummer. Hysteresis response of thermohaline circulation to fresh-water forcing revealed by an unmixed grain-size record from the North Atlantic. NAC8, Veldhoven, 2006. Oral presentation. Jonkers, L.P., M.A. Prins, G.-J. Weltje, A. Ganopolski, S. Troelstra, A. Kuipers & G.-J. Brummer. Hysteresis response of thermohaline circulation to fresh-water forcing revealed by an unmixed grain-size record from the North Atlantic. VAMOC-meeting, Cambridge, UK, 2006. Oral presentation.     Reports   Jonkers, L.P. 2005. Evaluating grain size distributions of terrigenous sediments as indicators of palaeoclimate. A case study from the Benguela region. M.Sc. thesis Vrije Universiteit Amsterdam, pp 36.   Jonkers, L.P. 2005. Weichselian fluvial dynamics in the Niederlausitz, eastern Germany, and a palaeoenvironmental reconstruction based on subfossil chironomids. Research report Vrije Universiteit Amsterdam, pp 41.   Research cruises:     2005: RV Pelagia Cruise BSIK/CAMP/LOCO/CIS. Peterhead (UK) - Texel (NL). Sediment trap recovery and redeployment in Irminger Sea. 2006: RRS Discovery Cruise BSIK/LOCO. St. John’s (Canada) - Reykjavik (Iceland). Sediment trap recovery and redeployment in Irminger Sea. 2007: RV Pelagia BSIK/CAMP/LOCO/VAMOC/CARBOCEAN. Texel (NL) - Galway (Ireland). Sediment trap recovery and deployment in the Irminger Sea, sediment coring, BOBO lander deployment.