Climate Change and Earth-Ocean-Atmosphere Systems.
Alexander Piotrowski is accepting applications for PhD students.
Alexander Piotrowski is available for consultancy.
Reconstructing the Ocean-Climate Link with Geochemical Tracers
The primary thrust of my research is to understand the link between ocean circulation and climate over recent earth history. The global ocean overturning is an important component of the earth’s climate system because the deep ocean hosts a large reservoir of carbon dioxide that exchanges with the atmosphere on short timescales, and its circulation also transports heat across the face of the planet. I am specifically interested in reconstructing changes in deep water mass source and structure and determining how these are linked with changes in deep ocean nutrient contents and overturning rate.
My research group at Cambridge uses radiogenic isotopes, including those of Nd and Pb, and other geochemical tools, in marine sediment samples at globally distributed sites to gain a wider view of past ocean geochemistry. A number of my studies have used Nd isotopes to examine South Atlantic deep water sourcing changes during deglacial circulation changes (Piotrowski et al., 2004 EPSL), glacial–interglacial transitions (Piotrowski et al., 2005, Science), and glacial millennial-scale variability (Piotrowski et al., 2008, EPSL). My research group is measuring Nd isotopes records at other key locations in the deep ocean, including the North Atlantic studies (Piotrowski et al., EPSL 2012; Elmore et al., 2010), deep Indian Ocean (Piotrowski et al., 2009, EPSL, Wilson et al., EPSL 2011), and Pacific (Elderfield et al. Science, 2012, Noble et al., EPSL in review). Our recent paper (Roberts et al., 2010, Science) was the first to compare past changes in water mass source and structure using Nd isotopes, to changes in the circulation strength using Pa-231/Th-230 from the Bermuda Rise (McManus et al., 2004), and showed that millennial-scale and glacial-interglacial changes in ocean circulation had different dynamics.
Former Ph.D. students –
David Wilson (2007 - 2011), now a post-doctoral researcher at Imperial College, London, utilized Nd and Pb isotopes of Fe-Mn leachates and foraminifera to reconstruct deep Indian Ocean water mass chemistry and sourcing during the last two glacial cycles. Also examining the chemical kinetics of Nd mobilization from marine sediments during acid reductive leaching of sediments
Taryn Noble (2007 - 2011), now a post-doctoral researcher at University of Tasmania, Australia, reconstructed past changes in Southern Ocean sediment sourcing and flux using radiogenic (Sr, Nd, Pb) and U-series isotopes, as well as studied past changes in deep ocean circulation from a transect cores from the Chatham Rise near New Zealand.
Natalie Roberts (2008 - 2013), now a Junior Research Fellow at St Johns College Cambridge, combined Nd isotopes and Pa/Th proxies to reconstruct North Atlantic deep water structure, source, and overturning strength. She continues to study North Atlantic circulation structure and circulation using novel proxies.
Current Ph.D. students –
Jake Howe (2011 - present) is studying Atlantic Ocean deep and intermediate water circulation and structure using Nd and Pb isotopes.
Rong Hu (2012 - present) is studying Pacific Ocean circulation and nutrient contents.
Piotrowski A.M., Galy, A., Nicholl, J.A.L., Roberts, N.L., Wilson, D.J.,Clegg, J., and Yu, J., (2012), Reconstructing deglacial North and South Atlantic deep water source using foraminiferal Nd isotopes, Earth and Planetary Science Letters 357-358, 289-297
Roberts, N.L., Piotrowski, A.M., Elderfield, H., Eglinton, T.I., Lomax, M.W., (2012), REE association with foraminifera, Geochimica et Cosmochimica Acta 94, 57-71
Elderfield, H., Ferretti P., Greaves, M., Crowhurst, S., McCave, I.N.,Hodell, D., Piotrowski, A.M., (2012), Evolution of ocean temperature and ice volume from the Mid Pleistocene Climate Transition, Science 337, 704, DOI:10.1126/science.1221294
Noble T.L., Piotrowski, A.M., Robinson L., and McManus J., (2012) Glacial to Holocene detrital flux and sediment provenance variations in the South Atlantic Southern Ocean, Earth and Planetary Science Letters 317-318, 374–385
Wilson, D.J., Piotrowski A.M., Galy, A., and McCave, I.N., (2012), A boundary exchange influence on deglacial neodymium isotope records from the deep western Indian Ocean, Earth and Planetary Science Letters 341-344, 35-47
Elmore, A.E., Piotrowski, A.M., White, J.D., Scrivner, A.E., (2011) Testing the extraction of past seawater Nd isotopic composition from North Atlantic deep sea sediments and foraminifera, G-cubed, 12, 1, doi:10.1029/2011GC003741
Roberts, N.L., Piotrowski, A.M., McManus, J., Keigwin, L., (2009) Synchronous deglacial overturning and water mass source changes, Science, 327 (5961). pp. 75-78.
Westbrook, G. K., Thatcher, K. E., Rohling, E. J., Piotrowski, A.M., Pälike H., Osborne A. H., Nisbet E. G., Minshull T. A., Lanoisellé M., James R. H., Hühnerbach V., Green, D., Fisher R. E., Crocker A. J., Chabert A., Bolton C., Beszczynska-Möller A., Berndt C., Aquilina A., (2009) Escape of methane gas from the seabed along the West Spitsbergen continental margin, Geophysical Research Letters, 36, L15608.
Piotrowski, A.M., Banakar V. K., Scrivner A. E., Elderfield H., Galy A., and Dennis A., (2009) Indian Ocean Circulation and Productivity during the Last Glacial Cycle, Earth and Planetary Science Letters 285, 179-189.
Yu J., Elderfield H., and Piotrowski, A.M. (2008) Seawater carbonate ion-d13C systematics and application to glacial–interglacial North Atlantic ocean circulation, Earth and Planetary Science Letters 271, 209-220.
Piotrowski, A.M., Goldstein, S.L., Hemming, S.R., and Fairbanks, R.G., and Zylberberg, D.R. (2008) Oscillating glacial northern and southern deep water formation from neodymium and carbon isotopes, Earth and Planetary Science Letters 272 394–405.
Kissel C., Laj C., Piotrowski A. M., Goldstein S. L., and Hemming S. R. (2008), Millennial-scale propagation of Atlantic deep waters to the glacial Southern Ocean, Paleoceanography, 23, PA2102, doi:10.1029/2008PA001624
Piotrowski, A.M., Goldstein, S.L., Hemming, S.R., and Fairbanks, R.G., (2005) “Temporal relationships of carbon cycling and ocean circulation at glacial boundaries”, Science 307, 5717, 1933-1938.
Piotrowski, A.M., Goldstein, S.L., Hemming, S.R., and Fairbanks, R.G., (2004) “Intensification and variability of ocean thermohaline circulation through the last deglaciation”, Earth and Planetary Science Letters 225, 205-220.
Piotrowski, A.M., Lee, D.-C., Christensen, J.N., Burton, K.W., Halliday, A.N., Hein, J.R., and Gunther, D., (2000) “Changes in erosion and ocean circulation recorded in the Hf isotopic compositions of North Atlantic and Indian Ocean ferromanganese crusts”, Earth and Planetary Science Letters 181, 315-325.
All Publications by Dr Alex Piotrowski