Freshwater ecosystems including streams, rivers, perennial ponds, lakes, and impoundments, which are collectively categorized as inland waters. Carbon sequestration rates in coastal estuaries, which are transition zones between rivers and oceans are presented in a separately. Carbon fluxes associated with aquatic ecosystems were assessed separately from those of terrestrial ecosystems in this assessment because of limited empirical aquatic data and lack of a large-scale, spatially explicit, carbon model that integrates both terrestrial and aquatic fluxes.
Inland waters’ fluxes included in this assessment are: (1) lateral transport of both dissolved inorganic carbon (DIC) and total organic carbon (TOC) in riverine systems, (2) gaseous carbon dioxide emissions in the form of carbon dioxide from riverine systems, (3) gaseous carbon dioxide emissions in the form of carbon dioxide from lacustrine systems, and (4) carbon burial rates in sediments of lacustrine systems. All of the ecoregion boundaries used in this chapter are consistent with those presented in the terrestrial component of the assessment.