Our group is interested in understanding marine biogeochemical cycling processes of the bioactive trace metals in marine phytoplankton (e.g., Fe, Zn, Cu, Co, Ni, Cd and Mo), especially focusing on their elemental and isotopic composition in phytoplankton, their concentrations in seawater, their sources in surface oceans, their vertical cycling processes in the water columns, and their roles in controlling algal community structure. We would also like to appreciate how anthropogenic aerosols and photochemical reactions influence the metal concentrations and speciation in seawater and the effects on algal community structure in the Western Pacific.

The trace metal composition in marine phytoplankton and their sources in the western Pacific and its marginal seas (ECS & SCS)
Marine phytoplankton plays a key role in cycling bioactive elements in the oceans or even on Earth. Their elemental composition is a fundamental basis in understanding marine biogeochemical cycles of bioactive elements, especially for vertical cycling processes in marine water columns. Our previous study found that the trace metal composition in the phytoplankton collected in the South China Sea was mainly dominated by extracellular portion (Ho et al. 2007). We hypothesized that the metals were originally derived from anthropogenic aerosols containing abundant dissolvable trace metals. Here, we will study the sources of the metals, their influence on the composition intracellularly and extracellularly in the algae, and their vertical export and cycling in the oceanic regions.
The isotopic fractionation of the biologically essential trace metals in marine phytoplankton
The isotopes of the trace metals are fractionated from seawater to microalgae through various biochemical processes in the cells. The information of the isotopic fractionation would provide unique and specific evidences in understanding the processes and mechanisms of marine biogeochemical cycle for the metals. The success of the study depends on the effective integration for algal culture techniques, blank control, chemical separation of the elements, and analytical techniques of the isotopes. We collaborate with the labs of Dr. Der-Chuen Lee at the Institute of Earth Sciences, Academia Sinica and Dr. Chen-Feng You at the Department of Earth Sciences, National Cheng-Kung University to carry out the study. We are measuring the isotopic fractionation of the metals in various algal species grown under different culture conditions by applying the cutting age analytical tools, the multi-collector ICPMS.

Atmospheric Forcing on Ocean Biogeochemistry: The effects of aerosol depositions and photolysis on marine phytoplankton community
Taiwan is located in subtropical to tropical regions and also right next to the continental China, the most rapidly industrializing region in the world. In this project, we study the impact of photolysis and the input of anthropogenic aerosols on algal growth and algal community structure, especially focusing on how the input of anthropogenic aerosols and photochemical degradation on LMWDOC influence trace metal concentrations in seawater, algal growth, and phytoplankton community structure. We plan to use source aerosols (e.g., biomass burning, fossil fuel burning) to study their dissolution behavior in seawater and their influence on algal community structure in our lab. Moreover, how photochemical degradation influences dissolvable trace metals concentrations and algal community structure would be appreciated by using EDTA or LMWFA as model compounds under various solar intensity conditions monitored in the lab. We plan to apply what we find in the lab to the South China Sea to evaluate the importance of the two atmospheric parameters on phytoplankton community structure.

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