Open AccessSeasonal shifts in diurnal variations of p CO 2 and O 2 in the lower Ganges River
Author(s) -
Haque Md. Morshedul,
Begum Most Shirina,
Nayna Omme K.,
Tareq Shafi M.,
Park JiHyung
Publication year - 2022
Publication title -
limnology and oceanography letters
Language(s) - English
Resource type - Journals
ISSN - 2378-2242
DOI - 10.1002/lol2.10246
Subject(s) - phytoplankton , dissolved organic carbon , seasonality , environmental science , flux (metallurgy) , diurnal temperature variation , monsoon , chemistry , atmospheric sciences , environmental chemistry , zoology , hydrology (agriculture) , ecology , oceanography , biology , nutrient , geology , geotechnical engineering , organic chemistry
High‐frequency, paired measurements of the partial pressure of CO 2 ( p CO 2 ) and dissolved O 2 were combined with dissolved organic matter (DOM) characterization to investigate diurnal (7:00–19:00) and seasonal variations in CO 2 dynamics in the lower Ganges River. Diurnal variations in p CO 2 shifted seasonally, concurring with changes in DOM optical properties, biodegradable DOM, and O 2 departures from atmospheric equilibrium (ΔO 2 ). Increased p CO 2 and CO 2 flux ( F CO 2 ) in August–September corresponded to monsoonal floods carrying more terrestrial materials. Lower dry‐season p CO 2 and F CO 2 concurred with higher ΔO 2 , and exhibited strong relationships with DO and pH, indicating a dominant influence of phytoplankton production. Despite large variations in p CO 2 , the year‐long positive F CO 2 implied that the lower Ganges acted as a CO 2 source, reaching 122 mmol m −2 d −1 . Increasing hydrologic variability and pollution in the Ganges Basin can amplify p CO 2 variations linked to seasonal shifts in terrestrial inputs and phytoplankton production.