Differences in ebullitive methane release from small, shallow ponds present challenges for scaling

A A P Baron; L T Dyck; H Amjad; J Bragg; E Kroft; J Newson; K Oleson; N J Casson; R L North; J J Venkiteswaran; C J Whitfield

doi:10.1016/j.scitotenv.2021.149685

Differences in ebullitive methane release from small, shallow ponds present challenges for scaling

Sci Total Environ. 2022 Jan 1:802:149685. doi: 10.1016/j.scitotenv.2021.149685. Epub 2021 Aug 14.

Authors

A A P Baron¹, L T Dyck¹, H Amjad², J Bragg³, E Kroft², J Newson³, K Oleson², N J Casson², R L North³, J J Venkiteswaran⁴, C J Whitfield⁵

Affiliations

¹ School of Environment and Sustainability, University of Saskatchewan, Saskatoon, SK S7N 3H5, Canada; Global Institute for Water Security, University of Saskatchewan, Saskatoon, SK S7N 3H5, Canada.
² Department of Geography, University of Winnipeg, Winnipeg, MB R3B 2E9, Canada.
³ School of Natural Resources, University of Missouri, Columbia, MO 65211, United States of America.
⁴ Department of Geography and Environmental Studies, Wilfrid Laurier University, Waterloo, ON N2L 3C5, Canada.
⁵ School of Environment and Sustainability, University of Saskatchewan, Saskatoon, SK S7N 3H5, Canada; Global Institute for Water Security, University of Saskatchewan, Saskatoon, SK S7N 3H5, Canada. Electronic address: colin.whitfield@usask.ca.

PMID: 34464805
DOI: 10.1016/j.scitotenv.2021.149685

Abstract

Small, shallow waterbodies are potentially important sites of greenhouse gas release to the atmosphere. The role of ebullition may be enhanced here relative to larger and deeper systems, due to their shallow water, but these features remain relatively infrequently studied in comparison to larger systems. Herein, we quantify ebullitive release of methane (CH₄) in small shallow ponds in three regions of North America and investigate the role of potential drivers. Shallow ponds exhibited open-water season ebullitive CH₄ release rates as high as 40 mmol m^-2 d^-1, higher than previously reported for similar systems. Ebullitive release of CH₄ varied by four orders of magnitude across our 15 study sites, with differences in flux rates both within and between regions. What is less clear are the drivers responsible for these differences. There were few relationships between open water-season ebullitive flux and physicochemical characteristics, including organic matter, temperature, and sulphate. Temperature was only weakly related to ebullitive CH₄ release across the study when considering all observation intervals. Only four individual sites exhibited significant relationships between temperature and ebullitive CH₄ release. Other sites were unresponsive to temperature, and region-specific factors may play a role. There is some evidence that where surface water sulphate concentrations are high, CH₄ production and release may be suppressed. Missouri sites (n = 5) had characteristically low ebullitive CH₄ release; here bioturbation could be important. While this work greatly expands the number of open-water season ebullition rates for small and shallow ponds, more research is needed to disentangle the role of different drivers. Further investigation of the potential thresholding behaviour of sulphate as a control on ebullitive CH₄ release in lentic systems is one such opportunity. What is clear, however, is that efforts to scale emissions (e.g., as a function of temperature) must be undertaken with caution.

Keywords: Ebullition; Greenhouse gas; Organic matter; Shallow water; Sulphate; Temperature.

MeSH terms

Atmosphere
Greenhouse Gases*
Methane* / analysis
Ponds
Temperature

Substances

Greenhouse Gases
Methane