We study the physical, biological, chemical and geological -driven exchange and transformation of elements in lakes and oceans, focusing on the cycles of vital elements including carbon, nitrogen, phosphorus, sulfur, and redox metals. We work on a diverse range of ecosystems including freshwater lakes, estuaries, coastal and deep oceans. We couple field and laboratory data with numerical modeling to seek mechanistic understanding of biogeochemical processes across scales in space and time.
Sediments receive materials from the water column. In sediments, materials undergo biogeochemical transformations that determine the fates of vital elements. Some materials/elements recycle back into the water column to support biological activities; some escape the system as gases and enter the atmosphere; some are buried into the deep sediments and leave the biological cycle (enter longer geological cycle). These processes regulate functioning of the aquatic ecosystems and impact local and global geochemical cycles. We are interested in quantifying these processes and understanding their controls and impacts. We seek answers to questions such as: 1) how does sediment affect and nutrient dynamics and ecology of the water, 2) how do sediment processes contribute to regional and global geochemical cycles in the long term, 3) and how can we use sediments to quantitatively reconstruct the past and predict the future biogeochemical conditions and trends.
Biology conveys energy and elements and shapes the chemistry of aquatic systems; biological activities, at the same time, are controled by geochemistry, the reactions and transport of life-supporting elements. We are interested in these interactions. Our past and present research topics include: 1) how primary producers respond to nutrient dynamics, particularly their nutrient storage mechanism as thriving strategy, 2) how invasive benthic bivalves change the sediment geochemistry and nutrient dynamics in the water column, and 3) microbial pathways of sediment nitrogen removal, denitrification vs anammox.