The Release of CO2 from Riverwaters – the Contribution of Excess CO2 from Groundwater

The dissolved CO 2 concentration of stream waters is an important component of the terrestrial carbon cycle and an important pathway for release of CO2 to the atmosphere. This study uses data from the UK's largest groundwater monitoring network to estimate the importance of groundwater in contributing excess dissolved CO2 to the atmosphere. The study shows that: the arithmetic mean concentration of excess dissolved CO2 in the groundwater was 4.99 mg C/I with a standard deviation of 2.53for the groundwater composition of excess dissolved CO2 analysis shows no statistical difference between years but does show a significant intra-annual effect and a significant difference between aquifersA weighted average of the estimate the areal export of excess dissolved CO2 from the groundwater of the catchment is between 1.4 and 2.9 t C/km2the flux of excess dissolved CO2 at the catchment outlet over the period between 1975 and 2002 averages 1.79 kt  C/year. If this were replicated across the UK then the flux of CO2 from rivers would be 0.65 Mt C/year.