Late summer peak in pCO2 corresponds with catchment export of DOC in a temperate, humic lake. Issue 2 (3rd April 2021)

• Record Type: Journal Article
• Authors: Doyle, Brian C.; de Eyto, Elvira; McCarthy, Valerie; Dillane, Mary; Poole, Russell; Jennings, Eleanor
• Is Part Of: Inland waters. Volume 11:Issue 2(2021)
• Page Start: 234
• Page End: 249
• Publication Date: 2021-04-03
• Subjects: carbon -- catchment -- CO2 emission -- lake -- pCO2 -- temperate maritime climate; Limnology -- Periodicals; Hydrology -- Periodicals; Aquatic biology -- Periodicals; Lake ecology -- Periodicals; Lakes -- Environmental aspects -- Periodicals; 551.48205
• DOI: 10.1080/20442041.2021.1893098
• Languages: English
• ISSNs: 2044-2041

Abstract

ABSTRACT: Humic lakes play a key role in the processing of organic carbon (OC) mobilised from their catchments, but knowledge of OC dynamics in lakes within maritime temperate climates is limited. Climate exerts a significant influence on mechanisms of OC capture, storage, and processing on the wet and cloudy west coast of Ireland. We examined a high-frequency dataset of partial pressure of CO2 ( p CO2 ) in the surface waters of Lough Feeagh collected over 1 year. The annual pattern in p CO2 ranged between 491 and 1169 µatm and was strongly related to allochthonous riverine OC inputs. In contrast to observations in colder climates, a single peak in p CO2 occurred in Lough Feeagh in early September. Generalised additive mixed modelling revealed that 2 variables, inflow water colour concentration (a reliable proxy for DOC concentrations) and lake Schmidt stability, together explained 68% of p CO2 variability. Both the statistical analysis and timing of the peaks in inflow DOC and p CO2 strongly suggested that catchment carbon export drove p CO2 supersaturation in the lake, and hence CO2 emissions. We estimated that between 217 and 370 t CO2 -C (0.55–0.94 t/ha) was emitted during the study period. These results highlight the interplay between catchment OC fluxes and climate in determining p CO2 dynamics in maritime temperate lakes.