Measuring impacts of Karst Systems on the Carbon Cycle

Programme

• 2:00   Prof. Chris Groves conference
• 3:30   Coffee break
• 4:00   CBEK brainstorming: presentation of new members, posters & talks
• 6:00   Drink

Abstract - Measuring Impacts of Karst Systems on the Carbon Cycle

Prof. Chris Groves, PhD (presenting author) and Autumn Turner, MS

Crawford Hydrology Laboratory - Western Kentucky University

Karst landscape/aquifer systems are primary developed within carbonate rocks such as limestone and dolomite. These rocks are very soluble in natural groundwater solutions of water and CO₂ gas, as carbonic acid. Most of this CO₂ comes from the atmosphere, either dissolved directly from the air, or from gas in the soil which is rich in CO₂ produced from decaying vegetation. That carbon also originally came from the atmosphere as this is the source of carbon in plants through photosynthesis.

Dissolution of carbonate minerals in carbonic acid consumes CO₂, and thus represents a process by which CO₂ is being removed from the atmosphere and is transferred to the oceans. Though there has been relatively little study of the geologic processes related to the carbon cycle, the work goes back several decades. A notable pioneer is Belgian Professor Camille Ek (Université de Liège). In the past several years this work has markedly increased, motivated by the increasing urgency for more detailed understanding of rates and processes of atmospheric carbon cycling in the face of increasingly intense climate change.

The net removal of CO₂ from the atmosphere from mineral weathering depends on the rates at which it is removed by mineral weathering on the continents and added back through precipitation in the oceans. More accurate direct measurement of the relevant fluxes is required to resolve these questions. Our laboratory has been refining methods for such measurements both in small carbonate basins and very large river basins with complex geology. Through analysis of 11 sub-basins of the 490,000 km² Ohio River basin in the eastern United States, we have developed a tentative model by which the inorganic carbon flux from a river basin can be predicted from existing, mapped geologic and climatic data without direct field measurements of water flow or chemistry. The model works well for basins that have at least about 10% area of carbonate rock outcrop, and produces good estimates independent of detailed lithology, soil types, land use, and other more detailed factors.