Ecological Indicators (Sep 2024)
Carbon budgets of lakes on the Tibetan Plateau: Highlighting non-negligible carbon emissions from small lakes
Abstract
The release of carbon dioxide (CO2) from lakes is a critical element of carbon (C) emissions from inland waters. Within the realm of climate change, the inquiries surrounding whether lakes on the Tibetan Plateau (TP) function as C sources or sinks and the magnitude of CO2 exchange flux from these lakes have garnered significant attentions. Nevertheless, accurately assessing the lakes’ contribution to the C budgets poses challenges due to data scarcity and methodological inaccuracies. By amalgamating data from literature reviews and field measurements for different sizes of lakes during the ice-free (IF) and ice-covered (IC) periods from 2016 to 2021, this study offers a refined estimate of the CO2 exchange flux and flux rate for lakes on the TP by including lakes ranging in size from 0.01 to 1 km2 (small lakes) in the C budgets. Findings revealed that the annual CO2 exchange flux of TP lakes amounted to 7.10 Tg C yr–1, with 6.56 Tg C yr–1 and 0.54 Tg C yr–1 during the IF and IC periods, respectively. Notably, small lakes contributed 0.76 Tg C yr–1, representing 10.65 % of the total lake CO2 emissions on the TP, which indicates the significant role of small lakes in estimating CO2 emissions from TP lakes. The CO2 exchange fluxes of small lakes showed significant variability during the IF period, with the origins of lake water replenishment possibly explaining this diversity, where glacial meltwater replenishment is likely a key contributing factor. In contrast, CO2 emissions from small lakes increased during the IC period. The view of this study is that the groundwater recharge with higher CO2 concentrations and the shallow nature of small lakes may be the main reasons for the increase in CO2 emissions from small lakes during this period. The study underscores that the contribution of small lakes to the CO2 budgets of TP lakes is substantial and warrants attention, particularly in elucidating the mechanisms driving CO2 emissions from small lakes.
