310 Heroy Geology Laboratory
Assistant Professor of Earth Sciences
Research and Teaching Interests
Trace elements in carbonate and paleo-redox Early diagenesis and authigenic carbonate (ikaite) Porewater modeling Gas hydrate, carbon and fluids in subduction zones
Global warming will affect marine ecosystems in complex ways. The lower oxygen solubility at higher temperatures could lead to a decrease in dissolved oxygen (deoxygenation). This would severely impact ocean life (including valuable fisheries) because oxygen is necessary for eukaryotic organisms, and plays an important role in biogeochemical cycling of carbon, nitrogen and other biochemically important elements. Forecasting ocean chemistry changes during perturbation of the climate system relies on the development of computer models and their calibration using proxy data on the state of the oceans. Development of geochemical proxies thus is key to enable us to use geological records to predict potential consequences of global warming. I'm interested in developing new and sensitive proxies for oxygenation, to investigate changes in oceanic redox conditions during abrupt warm events and oceanic anoxic events in the geological past. Currently, I'm focusing on iodine proxy in carbonate rocks and micro-fossils.
Complex biogeochemical reactions take place within the buried marine sediments, altering compositions of both solid phase sediments and their ambient porewaters. Organic matter diagenesis commonly lifts the levels of dissolved inorganic carbon and other solutes. Authigenic carbonate minerals can form under such condition. I'm interested in ikaite crystals (CaCO3·6H2O), a metastable hydrated carbonate mineral, that can precipitate rapidly in shallow sediment columns at relatively low temperature. Ikaite releases the hydration water at higher temperature, but may remain its macro-structure (pseudomorph, called glendonite) in outcropped old sedimentary rocks. Ikaite and glendonite have been used as indicators of cold bottom waters. The hydration water of ikaite also records oxygen isotopic composition of bottom water (or porewater), and may provide interesting information about past climate changes.
As a low temperature geochemist, I find that models are very useful tools for interrogating analytical data. I investigated glacial meltwater events in Antarctic fjords during the Anthropocene, by adapting the pioneering approach of modeling trends in δ18O in the porewaters of deep-sea cores, previously used to constrain the size of ice sheets during the Last Glacial Maximum. I hope to apply this approach in fjords of different sedimentary settings to reconstruct the glacier history and allow insight into the sensitivity of polar glaciers to abrupt warming events. Using a similar solute-transport-reaction model, I also looked at the halogen systematics in pore fluids of marine gas hydrate fields. Numerical model helped to quantify contributions of different sources to the porewater halogen pool, especially the iodine.
Large amount of methane are produced in marine sediments during organic matter decomposition and stored in gas hydrates. Gas hydrates may be an alternative energy source but global warming may also cause the dissociation of gas hydrates and massive release of gas. Many gas hydrate fields locate in subduction zones, close to the trench. Because of the tectonic compaction, hydrate fields are commonly featured with ubiquitous fluid conduits. Gas and fluid can migrate freely along these pathways up to very long distances. I use I-129 isotope to derive the age of organic source rocks of methane in subduction zones and learn about the long-term recycling of organic carbons.
Trace elements in carbonate and paleo-redox
Early diagenesis and authigenic carbonate (ikaite)
Gas hydrate, carbon and fluids in subduction zones
EAR 419/619 Environmental Aqueous Geochemistry EAR 111 Climate Change Past and Present
The goal for this course is to teach fundamental principles of aqueous geochemistry in a broad context of the Earth surface system including both terrestrial and marine settings. I will introduce basic analytical methods and geochemical models, that are commonly used to solve water related problems. Real-life dataset from applied environmental studies are also used. I will touch upon some frontier research topics in Earth Sciences after going through the necessary and closely relevant background. For example, carbonate chemistry and weathering will be taught in association with global carbon cycle, glacial/interglacial climate change and ocean acidification. Students interested in topics about paleoclimate or global environmental changes are encouraged to take this class as well.
This course is designed to introduce students of all disciplines to the science behind our understanding of Earth's climate system and changes in that system through time. Topics discussed in the class will include:
- The fundamentals of the climate system from the sun to the atmosphere to the oceans
- Overview of climate changes throughout the history of the Earth
- Past climate change from geological records
- Climate system driving forces and their interactions
- Natural vs. anthropogenic (human forced) climate change
- Impacts of climate change on natural systems and human activities
- Future predictions and their reliability
- Evaluating solutions to climate change on a variety of scales
EAR 419/619 Environmental Aqueous Geochemistry
EAR 111 Climate Change Past and Present
Recruiting both Master and PhD students
Lab spaces include a general chemistry lab, a clean lab, and also instrument room.
A new generation quadrupole ICP-MS, Bruker Aurora M90
Lab spaces include a general chemistry lab, a clean lab, and also instrument room.
22. Jin, L., Siegel, D.I., Lautz, L.K., and Lu, Z., 2012, Identifying streamflow sources during spring snowmelt using water chemistry and isotopic composition in semi-arid mountain streams. in press, Journal of Hydrology. 21. Jin, L., Whitehead, P.G., Futter, M.N. and Lu, Z., 2012, Modeling the impacts of climate change on flow and nitrate of the River Thames: Assessing potential adaptation strategies. in press, Hydrology Research.
20. Lu, Z., Rickaby, R.E.M., Kennedy H., Kennedy, P., Shaw S., Lennie, A., Pancost, R.D., Wellner, J., and Anderson, J.B., An ikaite record of late Holocene climate at the Antarctic Peninsula. Earth and Planetary Science Letters, vol.325-326, pp. 108-115, doi:10.1016/j.epsl.2012.01.036
19. Küpper, F. C., Feiters, M. C., Olofsson, B., Kaiho, T., Yanagida, S., Zimmermann, M. B., Carpenter, L. J., Luther, G. W., Lu, Z., Jonsson, M. and Kloo, L. (2011), Commemorating Two Centuries of Iodine Research: An Interdisciplinary Overview of Current Research. Angewandte Chemie International Edition, 50: 11598–11620. doi: 10.1002/anie.201100028
18. Lu, Z., Tomaru, H., and Fehn, U., 2011, Comparison of iodine dates from mud volcanoes and gas hydrate occurrences: relevance for the movement of fluids and methane in active margins. American Journal of Science. Vol. 311, (632–650), DOI 10.2475/07.2011.03
17. Lu, Z., Jenkyns, H.C., and Rickaby, R.E.M., 2010, Iodine to calcium ratios in marine carbonate as a paleo-redox proxy during oceanic anoxic events. Geology, 38(12), 1107–1110.
16. Lu, Z., Rickaby, R.E.M., Wellner, J., Georg, B., Charnley, N., Anderson, J.B. and Hensen C., 2010. Pore fluid modeling approach to identify recent meltwater signals on the west Antarctic Peninsula. Geochem. Geophys. Geosyst., 11, Q06017, Doi 10.1029/2009gc002949.
15. Scholz, F., Hensen, C., Lu, Z., and Fehn, U., 2010. Controls on the I-129/I ratio of deep-seated marine interstitial fluids: 'Old' organic versus fissiogenic 129- iodine. Earth and Planetary Science Letters, 294(1-2), 27-36.
14. Lu, Z., Fehn U., Zhao X., Kieser W.E. and Tomaru H., 2010, Comparison of three chemical extraction methods for I-129 determinations: Nuclear Instruments and Methods in Physics Research B, 268, 952–955.
13. Tomaru, H., Fehn, U., Lu, Z., Takeuchi, R., Inagaki, F., Imachi, H., Kotani, R., Matsumoto R., and Aoike, R., 2009, Dating of Dissolved Iodine in Pore Waters from the Gas Hydrate Occurrence Offshore Shimokita Peninsula, Japan: 129I Results from the D/V Chikyu Shakedown Cruise. Resource Geology, 59(4), 359-373.
12. Tomaru, H., Lu, Z., Fehn, U., and Muramatsu Y., 2009, Origin of hydrocarbons in the Green Tuff region of Japan: 129I results from oil ﬁeld brines and hot springs in the Akita and Niigata Basins : Chemical Geology, v. 264, p. 221-231.
11. Lu, Z., Hensen, C., Fehn, U., and Wallmann, K., 2008, Halogen and 129I systematics in gas hydrate fields at the northern Cascadia margin (IODP Expedition 311): Insights from numerical modeling: Geochem. Geophys. Geosyst., 9, Q10006, doi:10.1029/2008GC002156.
10. Lu, Z., Tomaru, H., and Fehn, U., 2008, Iodine ages of pore waters at Hydrate Ridge (ODP Leg 204), Cascadia Margin: implications for sources of methane in gas hydrates: Earth and Planetary Science Letters, v. 267, p. 654-665.
9. Lu, Z., Hensen, C., Fehn, U., and Wallmann, K., 2007, Old iodine in fluids venting along the Central American convergent margin: Geophysical Research Letters 34, L22604, doi: 22610.21029/22007GL031864.
8. Lu, Z., Fehn, U., Tomaru, H., Elmore, D., and Ma, X., 2007, Reliability of 129I/I ratios produced from small sample masses: Nuclear Instruments and Methods in Physics Research B, v. 259, p. 359-364.
7. Tomaru, H., Lu, Z., Fehn, U., Muramatsu, Y., and Matsumoto, R., 2007 Age variation of pore water iodine in the eastern Nankai Trough, Japan: evidence for different methane sources in a large gas hydrate field: Geology, v.35, p.1015-1018.
6. Tomaru, H., Lu, Z., Snyder, G.T., Fehn, U., Hiruta, A., and Matsumoto, R., 2007, Origin and age of pore waters in an actively venting gas hydrate field near Sado Island, Japan Sea: interpretation of halogen and 129I distributions: Chemical Geology, v. 236, p. 350-366.
5. Tomaru, H., Fehn, U., Lu, Z.L., and Matsumoto, R., 2007, Halogen systematics in the Mallik 5L-38 gas hydrate production research well, Northwest Territories, Canada: Implications for the origin of gas hydrates under terrestrial permafrost conditions: Applied Geochemistry, v. 22, p. 656-675.
4. Tomaru, H., Ohsawa, S., Amita, K., Lu, Z.L., and Fehn, U., 2007, Influence of subduction zone settings on the origin of forearc fluids: Halogen concentrations and I-129/I ratios in waters from Kyushu, Japan: Applied Geochemistry, v. 22, p. 676-691.
3. Fehn, U., Lu, Z., and Tomaru, H., 2006, Data Report: 129I/I ratios and halogen concentrations in pore water of Hydrate Ridge and their relevance for the origin of gas hydrates: A progress report: Proceedings of the Ocean Drilling Program, Scientific Results, v. 204.
2. Lu, Z., Ling, H.F., Zhou, F., Jiang, S., Chen, X., and Zhou, H., 2005, Variation of the Fe/Mn ratio of ferromanganese crusts from the Central North Pacific: implication for paleoclimate changes: Progress in Natural Science, v. 15, p. 530-537.
1. Ling, H.F., Jiang, S.Y., Frank, M., Zhou, H.Y., Zhou, F., Lu, Z.L., Chen, X.M., Jiang, Y.H., and Ge, C.D., 2005, Differing controls over the Cenozoic Pb and Nd isotope evolution of deepwater in the central North Pacific Ocean: Earth and Planetary Science Letters, v. 232, p. 345-361.
22. Jin, L., Siegel, D.I., Lautz, L.K., and Lu, Z., 2012, Identifying streamflow sources during spring snowmelt using water chemistry and isotopic composition in semi-arid mountain streams. in press, Journal of Hydrology.
21. Jin, L., Whitehead, P.G., Futter, M.N. and Lu, Z., 2012, Modeling the impacts of climate change on flow and nitrate of the River Thames: Assessing potential adaptation strategies. in press, Hydrology Research.