Dr. Ding He (Oliver) a post doctoral researcher working with Dr. Medeiros in the Department of Marine Sciences will present a seminar titled:
Application of Biomarkers and Compound Specific Stable Isotopes for the Assessment of Hydrology as a Driver of Organic Matter Dynamics in the Everglades Ecosystem:
The Everglades is a sub-tropical coastal wetland characterized among others by its hydrological features and deposits of peat. Formation and preservation of organic matter (OM) in soils and sediments in this ecosystem is critical for its sustainability. Hydrological processes are important divers in the origin, transport and fate of OM. Thus, OM dynamics in the greater Everglades was studied though various organic geochemistry techniques, especially biomarkers and compound specific δ13C/δD isotope analysis. The main objectives were focused on how different hydrological regimes in this ecosystem control OM dynamics, such as the mobilization of particulate organic matter (POM) in freshwater marshes and estuaries, and how organic geochemistry techniques can be applied to reconstruct paleo-hydrology. For this purpose OM in typical vegetation, floc, surface soils, soil cores, and estuarine suspended particulates were characterized in samples selected along hydrological gradients in the Water Conservation Area, Shark River Slough and Taylor Slough.
This research focused on three general themes: (1) Assessment of the environmental dynamics and source-specific particulate organic carbon (POC) export in a mangrove-dominated estuary. (2) Assessment of the origin, transport and fate of OM in freshwater marsh ridge and slough landscapes. (3) Assessment of paleo-hydrology in the Everglades though biomarkers and compound specific δ13C/δD analyses. This study reports the first estimate of POC loss from mangrove ecosystems in the Everglades, provides evidence for POM transport with regards to the formation of ridge and slough landscapes in the Everglades, and demonstrates the applicability of the combined biomarker and compound-specific stable isotope approach to generate paleohydrological data in wetlands. The data suggests that: (1) Carbon loss from mangrove estuaries is roughly split 50/50 between dissolved and particulate carbon; (2) Hydrological remobilization of POM from slough to ridge environments may play an important role in the maintenance of the Everglades freshwater landscape; and (3) Historical changes in hydrology have resulted in significant vegetation shifts from historical slough type vegetation to present ridge type vegetation, especially during the latter part of the 20th century.