F4 - The GHG footprint of a metropolitan area
Benjamin Archer 
Supervisors: Prof. Dr. Mark O.Gessner , Dr. Peter Casper , Dr. Gabriel Singer 
Introduction / Background
Freshwaters contribute disproportionately large concentrations of CH4 and CO2 to the atmosphere relative to their reduced global surface area (~3% of the global land surface (Downing et al., 2006)), and have the potential to swing continental carbon budgets. The conditions of urban areas (such as the urban heat island effect, nutrient pollution and morphological manipulation) are expected to increase the concentration of CH4 and CO2 released from freshwaters, yet few studies have investigated urban freshwater GHGs (Herrero Ortega et al., 2019). As urban areas are increasing (UN, 2019), freshwater systems are similarly increasingly urbanised, therefore have the potential to release greater amounts of GHGs.
An additional element of urban water systems is the drainage system. Comprised of sewer systems (gravity mains, pressure pipes, and wet wells), waste water treatment plants (WWTPs) and the river systems receiving treated waste water from the WWTPs, urban drainage systems present a source of GHGs that will similarly increase with urbanisation. However, little research into sewer systems as sources of GHG, or the net efflux of GHG from the integrated drainage system as a whole, has occurred (Mannina et al., 2018).
Realising climate change mitigation strategies outlined by the IPCC (2018) will require an intimate knowledge of the methane (CH4) and the carbon dioxide (CO2) cycles, in order to accurately modify carbon budgets and reverse greenhouse gas (GHG) driven atmospheric warming.
This project investigates CH4 and CO2 flux dynamics from urban freshwater and drainage systems in the city of Berlin, and aims to provide information for carbon budgets and water management policy by:
- Understanding the contribution of GHG from different elements of the sewer system and the drainage systems as a whole.
- Investigating GHG fluxes from surface freshwaters at a high temporal and within-site spatial resolution.
- Fig.1 Sources of greenhouse gas (GHG) from urban drainage systems. Waste water travels from its source to wastewater treatment plants (WWTPs) through the sewer system, then from WWTPs to receiving water bodies, each component of the urban drainage system has the potential to release GHGs to the atmosphere.
- © Mannina et al (2018)
This project will investigate CH4 and CO2 dynamics from Berlin’s sewer system through an annual sampling campaign. Flux measurements will be taken from gravity mains via street level manholes, from wet-well pumping stations and final pressure main outlets at WWTPs. This will be repeated for each season throughout the year. Additionally, investigation into fluxes from sewer systems will be undertaken at the UWI pilot plant, measuring gas phase CH4 and CO2 under treatment conditions such as nitrate addition (currently aimed at H2S abatement) and temperature.
This project will investigate CH4 and CO2 dynamics from Berlin’s ponds, lakes and rivers by developing and implementing in-situ high-resolution automated floating chambers, alongside a traditional sample based approach using closed-dynamic floating chambers, and physico-chemical sampling. Sampling will be carried out seasonally for one year.
Downing, J.A., Prairie, Y.T., Cole, J.J., Duarte, C.M., Tranvik, L.J., Striegl, R.G., McDowell, W.H., Kortelainen, P., Caraco, N.F., Melack, J.M. and Middelburg, J.J., 2006. The global abundance and size distribution of lakes, ponds, and impoundments. Limnology and Oceanography, 51(5).
Herrero Ortega, S., Romero González‐Quijano, C., Casper, P., Singer, G.A. and Gessner, M.O., 2019. Methane emissions from contrasting urban freshwaters: rates, drivers and a whole‐city footprint. Global change biology.
IPCC, 2018. Summary for Policymakers—Global warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty. Geneva, Switzerland: World Meteorological Organization.
Mannina, G., Butler, D., Benedetti, L., Deletic, A., Fowdar, H., Fu, G., Kleidorfer, M., McCarthy, D., Mikkelsen, P.S., Rauch, W. and Sweetapple, C., 2018. Greenhouse gas emissions from integrated urban drainage systems: Where do we stand? Journal of Hydrology, 559.
UN., 2019. World Urbanization Prospects: The 2018 Revision. United Nations New York.
- Other UWI projects: S1 ; kollegiate Daneish Despot .
- External collaborations: Michel Gunkel (Berliner Wasserbetriebe )
- Common topics: Interfaces in urban freshwater ecosystems