| Title |
Estimation of CO2 Net Atmospheric Flux in the Middle and Lower Nakdong River, and Influence Factors Analysis |
| Authors |
이은주 ( Eunju Lee ) ; 정세웅 ( Sewoong Chung ) ; 박형석 ( Hyungseok Park ) ; 김성진 ( Sungjin Kim ) ; 박대연 ( Daeyeon Park ) |
| DOI |
https://doi.org/10.15681/KSWE.2019.35.4.316 |
| Keywords |
CO2 emission; Data mining; Nakdong river; Net atmospheric flux; River pCO2 |
| Abstract |
Carbon dioxide(CO2) emission from rivers to the atmosphere is a key component in the global carbon cycle. Most of the rivers are supersaturated with CO2. At a global scale, the amount of CO2 emission from rivers is reported to be five-fold greater than that from lakes and reservoirs, but relevant data are rare in Korea. The objectives of this study is to estimate the CO2 net atmospheric flux(NAF) from the upstream of Gangjeong-Goryeong Weir(GGW), Dalseong Weir(DSW), Hapcheon-Changnyeong Weir(HCW), and Changnyeong-Haman Weir(CHW) located in Nakdong RiverSouth Korea) using field and laboratory experimentsand to apply data mining techniques to develop parsimonious prediction models that can be used to estimate CO2 NAF with physical and water quality variables that can becollected easily. As a result, the study sites were all heterotrophic systems that often released CO2 to the atmosphere, except when the algal photosynthesis was active.The median CO2 NAF was minimum 391.5 mg-CO2/m2day at GGW and maximum 1472.7 mg-CO2/m2day at DSW. The CO2 NAF showed a negative correlation with pH and Chl-a since the overgrowth of the algae consumed CO2 in the water and increased the pH. As the parsimonious multiple regression model and random forest model developed, this study showed an excellent performance with the Adj.R2 value higher than 0.77 in all weirs. Thus, these methods can be used to estimate CO2 NAF in the river even if there is no pCO2 measurement data. |