Spatial and Seasonal Variations in Dissolved Methane Across a Large Lake

Peacock, Mike ORCID: 0000-0002-3086-2854, Davidson, Scott J, Kothawala, Dolly N, Segersten, Joel and Futter, Martyn N (2023) Spatial and Seasonal Variations in Dissolved Methane Across a Large Lake. JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES, 128 (8).

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Official URL: http://dx.doi.org/10.1029/2023jg007668

Abstract

<jats:title>Abstract</jats:title><jats:p>Lakes process large volumes of organic carbon (OC), are important sources of methane (CH<jats:sub>4</jats:sub>), and contribute to climatic warming. However, there is a lack of data from large lakes >500 km<jats:sup>2</jats:sup>, which creates uncertainty in global budgets. In this data article, we present dissolved CH<jats:sub>4</jats:sub>, OC bioreactivity measurements, water chemistry, and algal biovolumes at 11 stations across Lake Mälaren, the third largest (1,074 km<jats:sup>2</jats:sup>) Swedish lake. Total phosphorus concentrations show that during the study period the lake was classed as mesotrophic/eutrophic. Overall mean CH<jats:sub>4</jats:sub> concentration from all stations, sampled five times to cover seasonal variation, was 2.51 μg l<jats:sup>−1</jats:sup> (0.98–5.39 μg l<jats:sup>−1</jats:sup>). There was no significant seasonal variation although ranges were greatest during summer. Concentrations of CH<jats:sub>4</jats:sub> were greatest in shallow waters close to anthropogenic nutrient sources, whilst deeper, central basins had lower concentrations. Methane correlated positively with measures of lake productivity (chlorophyll <jats:italic>a</jats:italic>, total phosphorus), and negatively to water depth and oxygen concentration, with oxygen emerging as the sole significant driver in a linear mixed effects model. We collated data from other lakes >500 km<jats:sup>2</jats:sup> (<jats:italic>n</jats:italic> = 21) and found a significant negative relationship between surface area and average CH<jats:sub>4</jats:sub> concentration. Large lakes remain an understudied contributor to the global CH<jats:sub>4</jats:sub> cycle and future research efforts should aim to quantify the spatial and temporal variation in their diffusive and ebullitive emissions, and associated drivers.</jats:p>

Item Type:	Article
Uncontrolled Keywords:	phosphorus, methane, Europe, climate change, eutrophication, greenhouse gas
Divisions:	Faculty of Science and Engineering > School of Environmental Sciences
Depositing User:	Symplectic Admin
Date Deposited:	21 Sep 2023 13:36
Last Modified:	18 Oct 2023 13:49
DOI:	10.1029/2023JG007668
Open Access URL:	https://doi.org/10.1029/2023JG007668
Related URLs:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3172942