Management actions mitigate the risk of carbon dioxide emissions from urban lakes

Lakes are recognized as important sources of carbon dioxide (CO2) emissions, which vary greatly across land use type. However, CO2 emissions from lakes in urban landscapes are generally overlooked despite their daily connections to human activity. Furthermore, the role of management actions in CO2 emissions remained unclear mostly because of the lack of long-term observations. Here, the CO2 partial pressure (pCO2) from two urban lakes (Lake Wuli and Lake Donghu) in eastern China were investigated based on 16-year (2002-2017) field mea-surements. This long-term measurements showed the annual mean pCO2 were 1150 & PLUSMN; 612 & mu;atm for Lake Wuli and 1143 & PLUSMN; 887 & mu;atm for Lake Donghu, with corresponding estimated flux of 21.12 & PLUSMN; 19.60 mmol m � 2 d-1 and 16.42 & PLUSMN; 20.39 mmol m � 2 d 1, respectively. This indicates significant CO2 evasion into the atmosphere. Strong links between CO2 and human-derived nutrients (e.g., ammonium) and dissolved organic carbon, dissolved oxygen, and trophic state index were found. Although pCO2 was relatively uniform across sites and seasons in each lake, substantial inter-annual variability with significant decreasing trends were found. The decrease in annual CO2 can be partly explained by the reduction of pollutant loadings with management actions, which held the hypotheses that management actions mitigated the CO2 emission risks. Overall, management actions (e.g., ecological restoration and municipal engineering) should be considered for better understanding the roles of anthropogenic aquatic ecosystems in carbon cycle.

Automated summary

This study investigated the CO2 partial pressure (pCO2) of two urban lakes in eastern China based on 16-year field measurements and found that CO2 emissions from these lakes were significant, with strong links to human-derived nutrients and organic carbon. The study also suggested that management actions, such as ecological restoration and municipal engineering, could help mitigate CO2 emissions in aquatic ecosystems.