Project highlights

  • The project aims to produce an empirically-based estimate of the greenhouse gas (GHG)
    emissions of U.K. ponds, understanding of controls on these emissions, and guidelines for
    pond management towards GHG emission mitigation.
  •  It will employ an extensive programme of field measurements using state of the art in situ
    analysers providing data at sub-daily resolution, combined with field surveys of ecosystem
    components, laboratory-based biogeochemical analyses, and experimental manipulations
    using mesocosms.
  • The project offers the opportunity to study and work across the UK at diverse sites and
    institutions, with diverse stakeholder engagement, and will inform the development of
    carbon offsetting and climate change mitigation schemes, supporting UK Government policy
    on land-management.


Recognition of the importance of inland waters for carbon processing has highlighted the need for
their consideration in climate change mitigation strategies. Small waterbodies remain under-studied,
but initial estimates suggest that while ponds (<0.1 ha) comprise c.9% of global lentic freshwater
area, they account for 15% of CO2 and 41% of CH4 diffusive emissions. Recent work involving the
supervisory team suggests that constructed ponds are consistently stronger CH4 emission sources
than natural ponds, partly because they tend to be located in agricultural landscapes where they
receive high organic matter and nutrient loadings. Conversely, carbon burial rates of 80–250 g C m-2
yr-1 determined for small, constructed U.K. ponds, if extrapolated nationally to all ponds < 2ha (420
km2), imply carbon burial comparable to all U.K. broadleaf/mixed woodlands (14,000 km2). While
such estimates suggest significant mitigation potential, uncertainties surrounding the GHG status of
small waterbodies are high, due to a paucity of empirical data, high spatio-temporal variability, and
limited process understanding, restricting our ability to upscale pond flux estimates for national
emissions reporting, or to develop effective mitigation strategies. Moreover, aquatic GHG fluxes
tend to exhibit positive temperature responses, underscoring an urgent need to assess emissions in
light of future climate warming.
The studentship offers a unique opportunity to advance understanding in this little studied area
using a range of novel experimental techniques and approaches, and accessing the large and diverse
population of ponds managed by the National Trust (NT). In conjunction with the NT (CENTA2 Level
2 Partner) it will promote cohesion between practitioners and academics, and offers the rare
prospect of making a palpable contribution to U.K. GHG mitigation efforts, and helping the NT to
deliver on their Net Zero commitments. The project will generate policy and public interest by virtue
of working within NT estates, and the use of state-of-the-art instrumentation funded through the
NERC GHG-Aqua capital grant (led by UKCEH with U Birmingham and the NT as project partners).
Associated public outreach with regard to domestic and other small waterbodies will further
enhance research impact.


UK Centre for Ecology & Hydrology


  • Climate and Environmental Sustainability


Project investigator


How to apply


The student will measure continuous sub-daily records of CO2 and CH4 fluxes in situ using state of the art automatic floating chambers equipped with telemetry, at replicated sites encompassing
gradients of pond morphometry, physico-chemistry and aquatic community structure. Samples will
be collected for characterisation of biogeochemical parameters, including N2O concentrations,
alongside in situ depth profiles, and combined with site habitat surveys and molecular analysis of
microbial communities to gain mechanistic understanding of controls on GHG fluxes. These will be
further complemented by, 1) assessments of sediment C inventories and sequestration rates derived
from sediment cores; 2) experimental manipulations using mesocosm approaches involving GHGs,
organic carbon degradation and characterisation assays, and microbial community analyses. Analysis
and interpretation of Earth Observation (EO) data, supplemented by outreach activities involving
public and pond organisation surveys, will allow upscaling of observations and assessment of
capacities for GHG mitigation, towards the development of management recommendations.

Training and skills

The student will have full access to CEH and UoB training programmes. At the project outset they will
co-develop a training plan, which will be regularly reviewed, to ensure they gain the skills required for
successful PhD completion. UKCEH Bangor operates a student liaison group to enable skill-sharing,
provide mutual support and ensure that generic training needs are met. The student will acquire
specialist skills in GHG flux measurement, microbiology, organic geochemistry, and EO data analysis.
They will also have opportunities to receive communication training and participate in public
engagement events at the NT.

Partners and collaboration

The UKCEH and UoB supervisors have collaborated for many years, including several major
UK/international carbon cycle projects. The student will be embedded within this experienced team
with diverse research expertise, and will work alongside other researchers at UKCEH, UoB, and with
wider stakeholders, and practitioners and policy leads at the National Trust, acquiring diverse
additional skills and experience. They will also be embedded within the UKCEH-led GHG-Aqua
programme, a £1m with a large network of academic, business, NGO and government partners.

Further details

Please contact Chris Barry ([email protected]) for further information.


Possible timeline

Year 1

1) Literature review of science area; 2) acquisition of skills in GHG flux measurement
working with UKCEH/UoB staff at UK research sites; 3) analysis of pilot GHG flux data; 4) trial
deployments of instrumentation; 5) acquisition of skills in Earth Observation techniques 5) initial
analysis and consultations to identify research sites; 6) experimental design and logistical planning for
field campaigns, and experimental manipulation approaches, including COVID contingency planning.
7) Initial stakeholder outreach activities and development of survey approaches to gather information
on domestic and ponds; to complement and inform EO approaches towards upscaling.

Year 2

1) Finalisation and initiation of field campaign; 2) Acquisition and analyses of field
campaign samples; 3) Analyses of data garnered from outreach activities; 3) Initiation of manipulation
experiments using mesocosms 4) conduct of C degradation assays associated with (3); 5) Continued
analysis of EO data to support upscaling of results; 6) commence preparation of manuscripts for
journal submission based on analysis of existing data and/or early results.

Year 3

1) Analysis and write-up of empirical GHG flux data (1st data chapter); 2) analysis and
write-up of mesocosm GHG findings (2nd data chapter); 3) analysis and write-up of mesocosm organic
carbon degradation and characterisation (3rd data chapter); 4) analysis of relationships between GHG
emissions and biogeochemical and environmental data, and upscaling of data for calculation of
regional and national emissions (synthesis chapter); 5) preparation of manuscripts for journal
submission; 6) completion of PhD thesis.

Further reading

Berberich, M.E., Beaulieu, J.J., Hamilton, T.L., Waldo, S. and Buffam, I. (2020) Spatial variability of
sediment methane production and methanogen communities within a eutrophic reservoir:
Importance of organic matter source and quantity. Limnol Oceanogr, 65: 1336-1358.
Davidson, T.A., Audet, J., Jeppesen, E. et al. (2018) Synergy between nutrients and warming
enhances methane ebullition from experimental lakes. Nature Clim Change 8, 156–160
Downing, JA. (2010) Emerging global role of small lakes and ponds: little things mean a
lot. Limnetica. 29(1), 9-24.
Gilbert, P.J., Cooke, D.A., Deary, M. et al. (2017) Quantifying rapid spatial and temporal variations of
CO2 fluxes from small, lowland freshwater ponds. Hydrobiologia 793, 83–93 (2017).
Hornbach D. J., Schilling, E. G. Kundel, H. (2020) Ecosystem Metabolism in Small Ponds: The effects
of Floating-Leaved Macrophytes. Water, 12, 1458; doi:10.3390/w12051458
Kosten S, Piñeiro M, de Goede E, de Klein J, Lamers LPM, Ettwig K. (2016) Fate of methane in aquatic
systems dominated by free-floating plants. Water Res. 1;104:200-207.
Kox MAR, Smolders AJP, Speth DR et al. (2021) A Novel Laboratory-Scale Mesocosm Setup to Study
Methane Emission Mitigation by Sphagnum Mosses and Associated Methanotrophs. Front
Microbiol. 26;12:652486. doi:10.3389/fmicb.2021.651103.
Reverey, F., Grossart, HP., Premke, K. et al. (2016) Carbon and nutrient cycling in kettle hole
sediments depending on hydrological dynamics: a review. Hydrobiologia 775, 1–20.
Rosentreter, J.A., Borges, A.V., Deemer, B.R. et al. (2021) Half of global methane emissions come
from highly variable aquatic ecosystem sources. Nat. Geosci. 14, 225–230
Peacock, M., et al. (2021). Global importance of methane emissions from drainage ditches and
canals. Environ. Res. Lett. 16: 044010. doi:10.1088/1748-9326/abeb36
Taylor, S., Gilbert, P.J., Cooke, DA., et al. (2019) High carbon burial rates by small ponds in the
landscape. Front Ecol Environ 2019; 17( 1): 25– 31, doi:10.1002/fee.1988
Torgersen, T., and Branco, B. (2007) Carbon and oxygen dynamics of shallow aquatic systems:
Process vectors and bacterial productivity, J. Geophys. Res., 112, G03016,
Webb, JR., Hayes, NM., Simpson, GL. et al. (2019) Widespread nitrous oxide under-saturation in farm waterbodies creates an unexpected greenhouse gas sink. PNAS. 116(20), 9814-9819.
West, W. E., Creamer, K. P. & Jones, S. E. (2015) Productivity and depth regulate lake contributions
to atmospheric methane. Limnol. Oceanogr. 61, S51–S61 (2015). (S1).
Wik, M., Thornton, B. F., Bastviken, D., MacIntyre, S., Varner, R. K., and Crill, P. M. (2014) Energy
input is primary controller of methane bubbling in subarctic lakes, Geophys. Res.
Lett., 41, 555– 560, doi:10.1002/2013GL058510
Yvon-Durocher, G. et al. (2014) Methane fluxes show consistent temperature dependence across
microbial to ecosystem scales. Nature 507, 488–491
Yvon-Durocher, G., Hulatt, C. J., Woodward, G. & Trimmer, M. (2017) Long-term warming amplifies
shifts in the carbon cycle of experimental ponds. Nat. Clim. Chang. 7, 209–213


UKCEH, the UoB and NT have a proven track record in COVID-19 risk-assessment, with delivery of
operations largely continuing successfully, albeit with modified practices, during the pandemic. The
potential for national or regional lockdowns will be monitored, and field sites selected to enable
continued operations as far as is safely possible. In their event, supervisory meetings will be held
online and the student equipped with a laptop and other facilities for home working. Notably, the use
of telemetered instrumentation reduces the requirement for numerous field visits. Travel between
institutions and sites will be planned according to conditions at the time.