CARBON DIOXIDE AND METHANE DYNAMICS OF SHALLOW LAKES FROM THE PAMPEAN PLAIN WITH ALTERNATIVE EQUILIBRIA REGIMES (Argentina)

BALIÑA, SOFÍA; SÁNCHEZ, MARÍA LAURA; IZAGUIRRE, IRINA; DEL GIORGIO, PAUL

Congreso; 10th International Shallow Lakes Conference; 2021

Carbon dioxide and methane emissions from inland waters constitute a significantcomponent of the global carbon cycle Among inland waters, shallow lakes are consideredbiogeochemical hotspots and are highly abundant in some landscapes The PampeanPlain in Buenos Aires, Argentina, is a region that hosts thousands of shallow lakes underdifferent alternative equilibria regimes, characterized as turbid phytoplanktonic and clearvegetated We followed seasonal carbon dioxide and methane diffusive (D) ebullitive (E)and plant mediated (PM) fluxes, as well as dissolved concentrations of both gases in thewater (DW) and several other limnological parameters, of two clear vegetated and twoturbid phytoplanktonic Pampean shallow lakes Clear and turbid lakes showed similarannual average carbon dioxide DW, but clear lakes had higher annual average methaneDW In spring and summer clear lakes were undersaturated in carbon dioxide DW whilst inwinter and fall they were oversaturated Turbid lakes were mainly oversaturated in carbondioxide DW, becoming undersaturated only in summer Regarding methane DW, all lakeswere oversaturated along the whole year Average D, E and PM fluxes of both gases weresimilar between the two lake regimes Methane D, E and PM fluxes of both regimes wereexponentially related to temperature Carbon dioxide D flux had a negative linear relationwith temperature in clear lakes, and a negative linear relation with dissolved oxygen andphytoplankton abundance in turbid lakes Carbon dioxide PM flux had a positive linearrelation with temperature in both lake types Average net emissions in terms of carbondioxide equivalents (eq) were similar between regimes, being 758 and 678 mmol carbondioxide eq day 1 m 2 for clear and turbid lakes, respectively These results providevaluable information about methane and carbon dioxide fluxes and their main drivers,along with the first comprehensive emission budget for inland waters in the Pampeanregion