Understanding the fate of the soil organic matter (SOM) in coastal wetlands allow for accurate assessments of ecosystem functions and services. Mineral associated organic matter (MAOM) is SOM that is physically and chemically stabilized through interactions with mineral surfaces, and is considered one of the most stable pools of SOM. Through both observational and experimental studies, MAOM was quantified along with the effect wetland restoration using dredged sediment has on MAOM pools in coastal wetland soils. First, a modified method quantified MAOM-C made up ~25% of the total C in a coastal wetland but 1% and <1% in a high mineral and high organic inland soil, respectively. An intact core study concluded dredged sediment reduced CO2 production for a high mineral soil, despite little change in MAOM-C. There was an increase in MAOM-C with the addition of dredged sediment in a bottle incubation study where MAOM-C increased and CO2 and CH4 rates decreased in the same fraction. In an observational field study, the restored wetland contained the lowest concentration of MAOM-C and MAOM-N, but had the greatest proportion of total C and N within the MAOM pool. There was also greater evidence for C stabilization through physical and chemical protection compared to biochemical protection. Across five geographical regions, restoration sites had lower total C, SOM, MAOM-C (p <0.001), but a grater the proportion of total C within the MAOM pool (p <0.001). An increase in proportion of MAOM-C suggests that soil C in restored wetlands may have longer residence times.
Anthony Mirabito
Dr. Lisa Chambers, Advisor
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