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.