EGS Seminar 18th October 2011

Tuesday 18th October, E34, John Dalton East Building, from 1.00-2.00 pm.

Sandwiches, coffee and tea are available from 12.30 pm in room E402.




Crusts and Carbon:
Ntwetwe Pan, Makgadikgadi Basin, northern Botswana


Dr Andrew Thomas, MMU


CO2 emissions from soils and sediments are approximately 10x greater than those from fossil fuel combustion. Organic matter in soil effectively locks up C and delays its entry to the atmosphere as CO2. The soil C store is, however, vulnerable and atmospheric warming is enhancing the global flux of CO2 from soils to the atmosphere. Disturbance and land use change can also trigger processes which can increase CO2 emissions. Understanding how the organic C store will be affected by changing climate remains an urgent research priority.


There is currently a poor understanding of the amount of C contained within soils of all southern African biomes. The extensive hyper-saline ephemeral lakes within the Makgadikgadi Basin in northern Botswana have been assumed to contain no organic carbon and contribute negligible CO2 to the atmosphere. The salt pan is devoid of vascular plant life, but a thin cover of cyanobacteria and algae thrive on the underside of the surface salt crust. This presentation explores the role of salt-biological crusts in the Makgadikgadi pan C cycle, presents data on the flux of CO2 from the variety of pan biomes and determines its sensitivity to changing temperatures and flooding. Alongside the scientific findings, I hope the talk will also convey some of the sense of wonder and occasional fear we experienced in undertaking the fieldwork in this remote and truly beautiful place.