Streams and rivers are an integral component of the freshwater carbon cycle as they provide the lateral transport of carbon from terrestrial environments to the ocean. Urbanization is one of the fastest growing land uses and it has major impacts on streams and rivers. This study examined twenty-eight watersheds varying in land uses from pre-restoration forested to urban in Charlotte, North Carolina. Their impervious cover ranged from 0.5–55%. The objective of this study was to examine alterations to freshwater carbon processes among watersheds of various land uses in multiple streams in Mecklenburg County, Charlotte, NC.

Surface water was collected at each site in addition to discharge measurements. Water quality parameters were analyzed including: DOC concentration, Specific UV Absorbance of DOC, DIC concentration, alkalinity concentration, δ ¹³C-DIC, major cations (Na⁺, K⁺, Mg ²⁺, and Ca²⁺), and anions (F^–, Cl^–, PO₄^3–, NO ^3–and SO₄^2–). DOC concentration ranged from 1.1–18 mg/L and SUVA values ranged from 0.2–18 L/mg*m. Alkalinity concentrations ranged from 0.1–3.8 meq/L and DIC concentrations ranged from 0.2–3.8 mM. δ¹³C-DIC values ranged from –18.0‰ to –7.4‰. Overall, DOC concentrations and SUVA values had weak negative relationships with percent impervious cover. DIC concentrations, alkalinity concentrations, δ¹³C-DIC values, all cations, and F^–, Cl^– , and SO₄^2– had strong positive relationships with percent impervious cover. PO₄^3– and NO ^3– had weak correlations with percent impervious cover. The increase in DIC, alkalinity, δ¹³C-DIC, and cations with high impervious cover was largely due to the increased chemical weathering of concrete materials in urban areas.