Dynaimcs of Colloids and associated Organic Carbon in Wetlands

Mobile colloids (1-1000 nm) play a dominant role in the transport and availability of organic carbon in deeper soil horizons. Despite the strong interactions between soil colloids and the stability of OC, detailed understanding of their role in C transport and accumulation is still incomplete particularly in redox-sensitive wetlands. Although wetlands cover only 8-10% of the world’s land surface, they store an estimated 20-30% of the global carbon (C) stocks. An improved understanding of the stabilization, fluxes, and distribution of C in wetlands is thus essential as concerns for the impacts of climate change increase. Seasonal wetting and drying not only creates biogeochemical “hotspots” for soil C cycling along upland-to-lowland transactions but also “hot moments” as the transition zones move seasonally. Therefore, redox-induced biogeochemical transformations are considered as the key processes that control the stabilization of soil organic carbon (OC) associated with mineral phases. Unfortunately, the operational definition of dissolved organic matter (DOM; <450 nm), overestimates the dissolved phase by including colloidal fractions of diameter <450 nm, which hinders accurate assessment of C turnover rates.