EAPSI: Long-term Carbon Storage in Old vs. New Wetland Sediments along Major River Deltas Influenced by Constructed Diversions

Arriola Jill, Chapel Hill NC

Investigators

Abstract

River deltas sequester large amounts of organic carbon (C) that originates from either upstream, as terrestrial mineral sedimentation, or through local marine vegetation that decays and is buried. Diminished sediment supply to river deltas can enhance the erosion and release of this sequestered C within deltaic wetlands, thereby potentially releasing CO2 back to the atmosphere through decomposition of organic matter (OM). The Yellow River (Huanghe) in China is the 2nd largest river in terms of sediment load and 6th in terms of drainage length in the world. The rate and location of sediment deposition in the Yellow River Delta (YRD) have been greatly altered by human actions in recent decades. This award supports research that will examine C burial within two different river courses of the YRD, identify the sources of the buried C, and compare these results to other major river deltas, such as the Mississippi River, to understand C storage variations between global rivers with constructed diversions. Under the supervision of Dr. Xuchen Wang, an expert in C dynamics within coastal wetlands in China and the United States, research will be performed at the Ocean University of China in Qingdao. The results of this study will contribute to the formulation of global management strategies focused on finding a balance between optimizing ecosystem services, such as wildlife habitat, and economic viability, such as commercial fisheries, within major river deltas. Sediment cores will be retrieved from wetlands along current and abandoned river courses within the YRD and analyzed for total organic C, total C, and total nitrogen using a CHN analyzer to quantify buried OM. Sediment and local YRD above and below-ground biomass, such as from Phragmites australis and Suaeda salsa, will be analyzed for ä13C isotopes, using an Isotope Ratio Mass Spectrometer, and n-alkanes, through Gas Chromatography, to determine the sources of the buried OM. Changes in odd-over-even predominance of n-alkanes will be utilized as sediment horizons and used to estimate rates of C burial. This NSF award is funded in collaboration with the Chinese Ministry of Science and Technology. This award under the East Asia and Pacific Summer Institutes program supports summer research by a U.S. graduate student and is jointly funded by NSF and the Ministry of Science and Technology of China.