Research Topics

Chem-/Bio- Sensors, Marine Biogeochemistry, Trace Elements, Environmental Analytical Chemistry

My research focuses on the development of bio/chemical sensors for in-situ studying elemental cycling and biogeochemical reaction dynamics in the marine sediments. A major theme in my research is to understand the spatial and temporal distributions and dynamics of solutes and bioactive metals associated with the benthic infaunal community, and to conceptualize heterogeneous biogeochemical transport – reaction processes in bioturbated deposits. The tools and techniques to multi-dimensionally measure solutes and trace elements in natural sediment do not exist, so the development of new methodology is an important part of my research.

One part of my research is to develop unique planar optical sensors and to quantitatively relate multidimensional patterns in sediment composition, for example, pore water solute or solid phase distributions and dynamics, to specific biogeochemical reaction rates and material fluxes by using the sensors. Compositional changes with depth in deposits are usually assumed steady and to occur in an overall average vertical progression. Significant heterogeneity and complex three dimensional reaction patterns over millimeter to meter scales can result, however, from the activities of bottom dwelling fauna. High resolution quantification of the multi-dimensional distributions of pore water solutes are thus essential for fundamental understanding of chemical diagenesis and elemental cycling in surficial sediments. Because the bioturbated zone in organic-rich surficial sediments is typically characterized by intense and complex coupling between multiple redox reactions associated with O2, H+, CO2, Mn(II), Fe(II), S(II-), nitrate, and exoenzyme. Thus, we are particularly interested in solutes consumed or generated by these reactions. My group and I have been developing 2-D optical sensors for these parameters and studying mechanisms of element transport – reaction processes in marine deposites.

Another important research activity in my lab is to study the biogeochemical cycling of micronutrient vitamins in marine system. Vitamins are naturally-occurring trace organic compounds essential for biological growth and functioning. Vitamin B12, for example, is a cobalt-containing coenzyme specifically required by most marine phytoplankton and is important in the regulation of primary production. With funding from NSF, we have been developing sensitive and specific ELISA methods for B12 analysis and investigating B12 potential source, distribution and transport in marine system. My group and I are current studying ultra-sensitive and specific biosensors for in-situ measurement of vitamin B12 in ocean and investigating B12 biogeochemical cycling and the transport – reaction processes controlling B12 behavior in sedimentary deposits and overlying water.

I am also interested in the monitoring and solution of practical environmental problems arising from metal and metalloid contaminants in estuarine and coastal systems, such as the distribution, speciation and removal of heavy metals. My laboratory has been investigating the distributions of heavy metals (such as Pb, V, Cd, Cr) around plant roots and the characteristics of metal transport into the root and spatial accumulation in the rhizophere using synchrotron radiation and ICPMS techniques. The Trace Element Laboratory has a range of facilities available for the relating research including a 400 sq. ft. class-100 trace metal clean laboratory, a Finnigan MAT Element 2 ICP-MS, a Perkin Elmer GFF-AAS and a HPLC.