My research focuses on utilizing field deployed optical sensor to monitor DOM flux between salt marsh and estuary during tidal movement in high frequency. Salt marshes are highly productive continental margin ecosystems, due to abundant solar radiation, water, and nutrients provided by tidal water. The unique bi-directional water movement introduced by tidal effect has a major impact on the formation and productivity of salt marsh and the material exchange between salt marsh and adjacent estuary.
Previous studies all adopted the conceptual model that salt marsh outwelling is a specific case of material exchange between terrestrial ecosystem and oceanic ecosystem. However, from the material exchange perspective, semi-diurnal tidal water movement provides a close linkage between salt marsh and adjacent estuary. This material linkage is the foundation of recognizing salt marsh and adjacent estuary as an integrated system. On one hand, labile materials such as amino acids and neutral sugars could be generated and consumed inside this system as the energy and material carrier between terrestrial part and aquatic part of this system. On the other hand, refractory materials such as humic substance could be transported from terrestrial vascular plants to the buried sediments in the ocean as the carrier of terrestrial productivity.
As a major term in carbon, energy, and nutrient budget for aquatic ecosystem, dissolved organic matter (DOM) has broad impact on food webs, carbon cycle, and nutrient retention/release. The frequency and period of DOM measurement is greatly increased by the use of reagent-free, low-cost, and reliable measurement with fluorescent and UV sensors measuring the chromophoric fraction of total DOM. Although fluorescent sensors can only measure concentration, UV absorbance in a wide spectral range (200nm-380nm) could potentially provide information on DOM composition. With the help of accurate direct real time water flux measurement and lab analysis of lability, DON, stable isotope signal (δ13C), and 3D excitation emission matrix spectroscopy (EEMs), a database of DOM quantity and quality exchanged between several comparative salt marshes and Long Island Sound could be established to study the dynamics of DOM behavior in the salt marsh-estuary system.