Release of CO2 from Riverwaters - the Contribution of Excess CO2 from Groundwater

• Published in: Biogeochemistry 2005-11, Vol.76 (2), p.299-317
• Main Authors: Worrall, F, Lancaster, A
• Format: Article
• Language: English
• Subjects: Aquifers; Arithmetic mean; Atmosphere; Carbon cycle; Carbon dioxide; dissolved carbon dioxide; Earth sciences; Earth, ocean, space; Exact sciences and technology; gas emissions; Geochemistry; Global carbon budget; Groundwater; groundwater flow; Headwaters; Hydrogeology; Hydrology; Hydrology. Hydrogeology; Mineralogy; Outlets; rivers; seepage; Silicates; Soil water; Standard deviation; Streams; Studies; Surface water; Water geochemistry; Water monitoring; Watersheds
• ISSN: 0168-2563; 1573-515X
• DOI: 10.1007/s10533-005-6449-4

The dissolved CO₂ 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: (i) the arithmetic mean concentration of excess dissolved CO₂ in the groundwater was 4.99 mg C/l with a standard deviation of 2.53 (ii) for 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 aquifers (iii) A 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/km⁲/year. (iv) the 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.