Ho, Tung-Yuan何東垣

Research Interests

Marine Biogeochemistry, Chemical Oceanography, & Ocean Sustainability Science. My primary research interest lies in marine trace metal biogeochemistry, where I investigate the cycling mechanisms of biologically active trace metals, their interactions with phytoplankton, and their application as tracers and proxies for studying material cycling in the ocean. To address these questions, we have conducted comprehensive laboratory culture experiments and field studies in the Northwestern Pacific Ocean (NWPO) and its marginal seas. My research focuses on several key areas: understanding how trace metals (e.g., nickel, iron) regulate N2 fixation and H2 production in marine diazotrophic cyanobacteria; examining the impacts of both anthropogenic and lithogenic aerosol deposition on trace metal cycling in surface waters of the NWPO; using trace metal isotopic compositions as proxies to investigate metal and material cycling; exploring the role of trace metals in coral bleaching; and assessing the major nutrient and trace metal requirements for seaweed aquaculture.

Representative Publications

Hsieh, C.-C. and T.-Y. Ho* (2024) Contribution of anthropogenic and lithogenic aerosol Fe in the East China Sea. Journal of Geophysical Research: Oceans  doi: 10.1029/2024JC021113

Wu, H.-Y., C.-C. Hsieh, and T.-Y. Ho* (2023) Trace metal dissolution kinetics of East Asian size-fractionated aerosols in seawater: The effect of a model siderophore. Marine Chemistry  doi: 10.1016/j.marchem. 2023.104277

Hsieh, C.-C., C.-F. You, and T.-Y. Ho* (2023) The solubility and deposition flux of East Asian aerosol metals in the East China Sea: the effects of aeolian transport processes. Marine Chemistry  doi: 10.1016/j.marchem. 2023.104268

Hsieh, C.-C., H.-Y. Chen, and T.-Y. Ho* (2022) The effect of aerosol size on Fe solubility and deposition flux: A case study in the East China Sea. Marine Chemistry doi: 10.1016/j.marchem.2022.104106

Chen, C.-C., I. B. Rodriguez, Y.-L. L. Chen, J. P. Zehr, Y.-R. Chen, S.-T. D. Hsu, S.-C. Yang, and T.-Y. Ho* (2022) Nickel superoxide dismutase protects nitrogen fixation in TrichodesmiumLimnology and Oceanography:Letters doi: 10.1002/lol2.10263

Li, H.-T., S. Tuo, M.-C. Lu, and T.-Y. Ho* (2022) The effects of Ni availability on H2 production and N2 fixation in a model unicellular diazotroph: the expression of hydrogenase and nitrogenase. Limnology and Oceanography doi: 10.1002/lno.12151

Liao, W.-H., S. Takano, H.-A. Tian, H.-Y. Chen, Y. Sohrin, and T.-Y. Ho* (2021) Zn elemental and isotopic features in the sinking particles of the South China Sea: the implications to its sources and sinks. Geochimica et Cosmochimica Acta  doi: 10.1016/j.gca.2021.09.013.

Reich*, H. G., W.-C. Tu, I. B. Rodriguez, Y. Chou, E. F. Keister, D. W. Temp, T. C. LaJeunesse, and T.-Y. Ho* (2021) Iron availability modulates the response of endosymbiotic dinoflagellates to heat stress.  Journal of Phycology doi: 10.1111/jpy.13078.

Wang, B.-S. and T.-Y. Ho* (2020) Aerosol Fe cycling in the surface water of the Northwestern Pacific Ocean. Progress in Oceanography doi: 10.1016/j.pocean.2020.102291.

Reich*, H. G., I. B. Rodriguez, T. C. LaJeunesse, and T.-Y. Ho* (2020) Endosymbiotic dinoflagellates pump iron: differences in iron and other trace metal needs among the Symbiodiniaceae. Coral Reefs doi: 10.1007/s00338-020-01911-z.

Liao, W.-H., S. Takano, S.-C. Yang, K.-F. Huang, Y. Sohrin, and T.-Y. Ho* (2020) Zn isotopic composition in the water column of the Northwestern Pacific Ocean: the importance of external sources. Global Biogeochemical Cycles doi: 10.1029/2019GB006379.

Tuo, S., I. B. Rodriguez, and T.-Y. Ho* (2019) H2 accumulation and N2 fixation variation by Ni limitation in CyanotheceLimnology and Oceanography doi: 10.1002/lno.11305.

Yang, S.-C., J. Zhang, Y. Sohrin, and T.-Y. Ho* (2018) Cadmium cycling in the water column of the Kuroshio-Oyashio Extension region: Insights from dissolved and particulate isotopic composition. Geochimica et Cosmochimica Acta doi: 10.1016/j.gca.2018.05.001.

Highlights

Demonstrating the roles of Ni availability on controlling nitrogen fixation and hydrogen production in marine diazotrophic cyanobacteria. Ni is an essential cofactor in Ni superoxide dismutase (SOD) & Ni-Fe uptake hydrogenase, two enzymes responsible for removing superoxides and regulating hydrogen cycling in some marine diazotrophic cyanobacteria, respectively. Applying trace metal defined culture techniques (Ho et al. 2003), my group has demonstrated the essential role of Ni on nitrogen fixation and hydrogen production (Ho 2013; Rodriguez and Ho 2014; Rodriguez and Ho 2017; Tuo et al. 2019). Our most recent study found that Ni limitation results in one order of magnitude higher hydrogen accumulation rates in the low Ni than high Ni treatments (Tuo et al. 2019). We propose that Ni deficiency decreases hydrogenase expression and leads to hydrogen accumulation and nitrogen fixation reduction in marine diazotrophic cyanobacteria. We are currently evaluating our custom-made antibodies for Ni-SOD and Ni-Fe hydrogenase and shall apply them to investigate how Ni availability or other environmental factors influence cyanobacterial nitrogen fixation and hydrogen production in the ocean.

Proving the importance of anthropogenic aerosol deposition on trace metal cycling in the surface water of the Northwestern Pacific Ocean (NWPO). We have pioneered studies for the impacts of anthropogenic aerosol deposition on trace metal cycling in the oceanic regions. Illustrated by the distribution patterns of trace metal composition and their ratios in seawater, plankton, suspended and sinking particles, and aerosols, our series field studies have demonstrated that anthropogenic aerosols are the major trace metal source in the surface water of the South China Sea, Western Philippine Sea, the Kuroshio, and the NWPO (e.g., Ho et al. 2007; Liao et al. 2017; Liao and Ho 2018). The impact shall not only be on trace metal cycling but also on phytoplankton community structure and material cycling in the ocean.

Applying trace metal isotopic composition as proxies to study trace metal and material cycling in the ocean. Trace metal isotopic composition are powerful tracers and proxies to study physical and biogeochemical processes in the ocean. For example, Yang et al. (2018) found that Cd isotope fractionation can match either a closed or open system Rayleigh fractionation model, depending on the relative contribution of physical and biogeochemical processes on its cycling. Liao et al. (2020) found that anthropogenic aerosol deposition may play an important role in causing the variations of its elemental and isotopic composition in oceanic surface water globally. A series of trace metal isotopic studies on Fe and Ni are currently ongoing in our laboratory.

Investigating trace metal requirement in Symbiodiniaceae. Our systematic and seminal studies have obtained fundamental understanding for trace metal requirement in Symbiodiniaceae (Rodriguez et al. 2016; Rodriguez and Ho 2017, 2018; Reich et al. 2020). We found that Symbiodiniaceae possesses high Fe and Zn requirement. Our most recent studies have indicated that Fe requirement in Symbiodiniaceae may be significantly elevated to sustain their growth at relatively high ambient seawater temperature (Reich et al. in prep.). We are carrying out experiments to demonstrate whether Fe availability is an important factor affecting coral bleaching in coral reef ecosystem under global warming.

 

  • Postdoctoral Fellow
    Department of Geosciences
    Princeton University, USA (2000~2003)
  • Ph.D.
    Marine Sciences Research Center
    State University of New York at Stony Brook, USA (2000)
  • M.S.
    Institute of Oceanography
    National Taiwan University, Taiwan (1994)
  • B.S.
    Department of Marine Resources
    National Sun Yat-sen University, Taiwan (1989)

研究人員登入