Lake surface cooling drives littoral-pelagic exchange of dissolved gases

Abstract

The extent of littoral influence on lake gas dynamics remains debated in the aquatic science community due to the lack of direct quantification of lateral gas transport. The prevalent assumption of diffusive horizontal transport in gas budgets fails to explain anomalies observed in pelagic gas concentrations. Here, we demonstrate through high-frequency measurements in a eutrophic lake that daily convective horizontal circulation generates littoral-pelagic advective gas fluxes one order of magnitude larger than typical horizontal fluxes used in gas budgets. These lateral fluxes are sufficient to redistribute gases at the basin-scale and generate concentration anomalies reported in other lakes. Our observations also contrast the hypothesis of pure, nocturnal littoral-to-pelagic exchange by showing that convective circulation transports gases such as oxygen and methane toward both the pelagic and littoral zones during the daytime. This study challenges the traditional pelagic-centered models of aquatic systems by showing that convective circulation represents a fundamental lateral transport mechanism to be integrated into gas budgets.

The carbon budget of continents is strongly influenced by overlooked lake littoral zones

“…Another part of the C fixed by littoral plants is exported to the pelagic zone and further downstream. Notably, the export of C from the littoral to the pelagic zone is a pathway rarely addressed, although it has been explored for CH4 [33][34][35] . Hence, CO2 evasion from inland waters is assumed to predominantly result from the transport of terrestrial organic and inorganic C into pelagic waters 30,36,37 , but does not consider what was produced in the littoral.…”

Features of mixing the water mass of a small lake during night cooling

“…Семь температурных датчиков (TR-1060 RBR Ltd, точность 0,005 °С) размещались в верхнем слое от 0,69 до 3 м через 33 см, а остальные датчики -на глубинах 3,0; 4,0; 5,0; 6,0; 6,5 м Дальнейшее последовательное рассмотрение энергетических параметров проводится в рамках одномерного приближения, когда параметры считаются однородными по горизонтали. Предполагается, что крупномасштабное движение отсутствует и горизонтальной адвекцией можно пренебречь, в отличие от озер с обширными мелководными литоральными зонами [Doda et al, 2024].…”