Patterns in pCO2 in boreal streams and rivers of northern Quebec, Canada

Here we examine the patterns in carbon dioxide partial pressure (pCO(2)) measured in a number of small boreal streams (<5 km in length) in the northwestern boreal region of Quebec during the ice-free season and compare these to the patterns found in a major river (Eastmain River) and in a tributary in the same region. All systems were consistently supersaturated in CO2 (range 450 to 5000 mu atm) streams having both higher (mean 1850 mu atm) and more variable pCO(2) than that of rivers (range 550 to 800 matm). Stream pCO(2) was positively related to DOC concentration and stream segment length, both suggesting a direct influence of the surrounding landscape. Calculated stream water-air CO2 fluxes ranged from 700 to over 3000 mg C m(-2) d(-1), up to 2 orders of magnitude higher than those measured in large rivers and lakes of the same region. Small streams, despite their extremely reduced areal coverage (1% of the aquatic surface), accounted for 25% of the total aquatic C emissions, and the resulting areal stream fluxes were comparable to those measured in different soils or wetlands in the region.