Streams emit a significant amount of CO2 globally into the atmosphere. Most of the emitted carbon is allochthonous, meaning terrestrially derived carbon (in the form of dissolved organic and inorganic carbon) that is exported to streams due to hydrologic processes. Inorganic carbon inputs from watersheds to streams can result from soil respiration and subsurface chemical weathering. Stream CO2 emissions are often reported to be supported by terrestrial soil respiration, meaning carbon fixed by plants is emitted back to the atmosphere. Stream CO2 emission can also occur due to DIC from weathering (calcite and silicate), indicating carbon loss from long-term subsurface storage. It is not understood how the regulation of these two different pathways for carbon (soil respiration and weathering) entering into streams varies across different biomes. Additionally, this export or loss of terrestrial carbon to streams is not inherently accounted for when terrestrial methods such as tower-based eddy covariance estimates are used to determine net carbon source or sinks. Here we ask: What are the annual DIC losses from soil to streams due to soil respiration and weathering and what are the watershed-scale predictors? We addressed this question over 10 ecologically distinct biomes using data collected by National Ecological Observatory Network (NEON). Our preliminary estimates suggest <1% to 25% of watershed Net Ecosystem Productivity (NEP) lost annually occurred in the form of DIC from soil respiration during 2019-2021. Groundwater chemistry suggests more DIC entering into streams as a result of silicate weathering reaction compared to calcite weathering based on stoichiometric ratios, though reaction rates for calcite weathering are significantly faster. Overall, regions with higher soil subsurface flow and soil organic matter had higher DIC export to streams. This work will lead to the representation of these processes into global-scale earth system models.