COMPARING DEGASSING RATES OF CARBON DIOXIDE FROM FIRST ORDER STREAMS IN SUBURBAN BALTIMORE, MARYLAND, USA

Streams are important contributors to the carbon cycle by transporting carbon into larger bodies of water and eventually into the oceans. During this process carbon dioxide is also released into the atmosphere, and previous studies have suggested a potential intensification of these fluxes due to anthropogenic activities associated with urban development. To investigate this possibility, four first order streams exhibiting different characteristics of urbanization and lithology were sampled in a suburban region of Baltimore, Maryland with the purpose of estimating their respective carbon dioxide fluxes to the atmosphere. Stream temperature, pH, and alkalinity values, in particular, were measured for eight weeks and used to calculate dissolved inorganic carbon, dissolved carbon dioxide, and carbon dioxide fluxes of individual streams. We found that the average fluxes of the four streams range from 18.8 to 61 μg C/s-m² during the studied time interval of 2013, and these results are comparable with those found for both boreal and northern peatland streams. In particular, the data show that the most forested stream, which flows through calcareous rock formations, consistently had the largest flux of carbon into the atmosphere. This large flux is likely the result of the higher alkalinity levels measured in this stream compared to the other three studied streams, which flow through mostly silicate catchments. Two of these streams, in particular, have contrasting levels of impervious surfaces (25% and 73%), yet they both emitted similar levels (p>0.05) of carbon dioxide to the atmosphere. These results then indicate that lithology appears to have a stronger effect on overall carbon emissions of each of the streams in relation to their level of urbanization.