Dissolved Carbon Concentrations and Emission Fluxes in Rivers and Lakes of Central Asia (Sayan–Altai Mountain Region, Tyva)

• DOI: 10.3390/w15193411
• Publication Date: 2023-09-28T09:55:54Z
• Authors: Arisiya A. Byzaakay; Larisa G. Kolesni...; Iury Ia. Kolesnic...; Aldynay O. Khovalyg; Tatyana V. Raudina; Anatoly S. Prokus...; Inna V. Lushchaeva; Zoia N. Kvasnikova; Sergey N. Vorobyev; Oleg S. Pokrovsky; Sergey Kirpotin
• Keywords: Biogeochemical Cycle; Subarctic climate; Thermokarst

The carbon (C) cycle in inland waters, including concentrations and dioxide (CO2) emissions from water surfaces, are at the forefront of biogeochemical studies, especially regions strongly impacted by ongoing climate change. Towards a better understanding C storage, transport emission Central Asian mountain regions, an area knowledge that has been extremely poorly studied until now, here, we carried out systematic measurements dissolved CO2 rivers lakes located along macrotransect various natural landscapes Sayan–Altai region, high mountains Western Sayan northwest Tyva to arid (dry) steppes semideserts intermountain basins southeast on border with Mongolia. New data major hydrochemical parameters fluxes (fCO2) gathered floating chambers organic inorganic (DOC DIC, respectively) collected over four main hydrological seasons allowed us assess current status these bodies order judge possible future changes under warming. We further tested impact permafrost, river watershed size, lake as well ‘internal’ drivers (pH, mineralization, matter quality bacterial population) concentration this region compared them available other subarctic settings. found strong environmental control pattern bodies, thermokarst being drastically different lakes. In freshwater lakes, pCO2 negatively correlated O2, whereas temperature exerted positive large rivers. Overall, complexity counteracting external internal exchange between surfaces atmosphere (CO2-rich underground DIC influx lateral soil subsurface water; production column due particulate OC biodegradation; uptake aquatic biota) precluded establishing simple causalities single parameter fCO2 season-averaged flux measured study was comparable, some uncertainty, terrestrial ecosystems which were assessed works.