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Anthropogenic influences significantly modify the hydrochemical properties and material flow in riverine ecosystems across Asia, potentially accounting for 40–50% of global emissions. Despite the pervasive impact on Asian rivers, there is a paucity of studies investigating their correlation with carbon dioxide (CO 2) emissions. In this study, we computed the partial pressure of CO 2 (pCO 2) using the carbonate equilibria-based model (pCO 2 SYS) and examined its correlation with hydrochemical parameters from historical records at 91 stations spanning 2013–2021 in the Ganga River. The investigation unveiled substantial spatial heterogeneity in the pCO 2 across the Ganga River. The pCO 2 concentration varied from 1321.76 μatm, 1130.98 μatm, and 1174.33 μatm in the upper, middle, and lower stretch, respectively, with a mean of 1185.29 μatm. Interestingly, the upper stretch exhibited elevated mean pCO 2 and FCO 2 levels (fugacity of CO 2 : 3.63 gm2d−1) compared to the middle and lower stretch, underscoring the intricate interplay between hydrochemistry and CO 2 dynamics. In the context of pCO 2 fluctuations, nitrate concentrations in the upper segment and levels of biological oxygen demand (BOD) and dissolved oxygen (DO) in the middle and lower segments are emerging as crucial explanatory factors. Furthermore, regression tree (RT) and importance analyses pinpointed biochemical oxygen demand (BOD) as the paramount factor influencing pCO 2 variations across the Ganga River (n = 91). A robust negative correlation between BOD and FCO 2 was also observed. The distinct longitudinal patterns of both parameters may induce a negative correlation between BOD and pCO 2. Therefore, comprehensive studies are necessitated to decipher the underlying mechanisms governing this relationship. The present insights are instrumental in comprehending the potential of CO 2 emissions in the Ganga River and facilitating riverine restoration and management. Our findings underscore the significance of incorporating South Asian rivers in the evaluation of the global carbon budget. [Display omitted] • PCO 2 concentration higher in upstream region than downstream region of Ganges. • Nitrate predict pCO 2 well in upstream region. • BOD and DO are best predictors of pCO 2 in downstream regions. • BOD emerged as a crucial influencing factor for pCO 2 across the Ganga River. [ABSTRACT FROM AUTHOR]

Heavy carbon industries produce solid side stream materials that contain inorganic chemicals like Ca, Na, or Mg, and other metals such as Fe or Al. These inorganic compounds usually react efficiently with CO 2 to form stable carbonates. Therefore, using these side streams instead of virgin chemicals to capture CO 2 is an appealing approach to reduce CO 2 emissions. Herein, we performed an experimental study of the mineral carbonation potential of three industrial steel slags via aqueous, direct carbonation. To this end, we studied the absorption capacities, reaction yields, and physicochemical characteristics of the carbonated samples. The absorption capacities and the reaction yields were analyzed through experiments carried out in a reactor specifically designed to work without external stirring. As for the physicochemical characterization, we used solid-state Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscope (SEM). Using this reactor, the absorption capacities were between 5.8 and 35.3 g/L and reaction yields were in the range of 81–211 kg CO 2 /ton of slag. The physicochemical characterization of the solid products with solid FTIR, XRD and SEM indicated the presence of CaCO 3. This suggests that there is potential to use the carbonated products in commercial applications. • Mineral aqueous carbonation of three industrial steel slags. • Absorption capacities are between 5.8 and 35.3 g/L. • Reaction yields obtained were in the range of 81–211 kg CO 2 /ton of slag. • In situ analysis showed evidence for the formation of carbonate ions. • The physicochemical characterization showed CaCO 3 in the solid products. [ABSTRACT FROM AUTHOR]