Abstract
The atmosphere–land–water connectivity of dissolved organic carbon (DOC) is not altogether accounted in major rivers of India despite recent researches highlighting its importance. We studied the coupled effect of atmospheric deposition (AD) and local land use on DOC buildup in Ganga River for a period of 6 years. The AD-OC input increased consistently over time and there was over 1.5- to 1.8-fold increase in 2012 relative to 2007. Microbial activity and water soluble organic carbon (WSOC) in sub-catchment and DOC in land surface runoff increased consistently over time along the gradient of AD input. The river DOC showed positive correlation (R 2 = 0.24–0.84; p < 0.001) with AD-OC and runoff DOC and WSOC showed positive correlation (R 2 = 0.96; p < 0.001) with soil microbial activity. Principal component analysis segregated study sites into four groups demarcating source relationships. Our study, that forms the first report on atmosphere–land–water transfer of organic carbon in Ganga River, suggests that future climate models should include region-specific time series data on changing state of atmosphere– land–water connectivity and associated shift in carbon balance of major rivers for more accurately predicting the climate change drivers.
Highlights
The human alteration of carbon cycle is a key node of perturbed Earth System functions such as climate change, global transport of pollutants, changing biogeochemical cycles, ecosystem productivity and plant species shift (Reich et al 2006; Ramanathan and Garmichael 2008; Jurado et al 2008; Langley and Megonigal 2010; Pandey 2011; Pandey et al 2014a)
Month-wise, the atmospheric deposition (AD)-organic carbon (OC) was highest in December (Byds, Assi ghat (Asht), Rajghat upstream (Rjus) and Rajghat downstream (Rjds)) and January (Adpr, Shultankeshwar ghat (Sltt) and Bypass upstream (Byus)) (Fig. 4) the differences in atmospheric deposition of organic carbon (AD-OC) fluxes between these months were not significant
Our study showed that the hydrological transport of carbon as influenced by land use and AD-OC is an important vector of dissolved organic carbon (DOC) to Ganga River in Varanasi region
Summary
The human alteration of carbon cycle is a key node of perturbed Earth System functions such as climate change, global transport of pollutants, changing biogeochemical cycles, ecosystem productivity and plant species shift (Reich et al 2006; Ramanathan and Garmichael 2008; Jurado et al 2008; Langley and Megonigal 2010; Pandey 2011; Pandey et al 2014a). Despite the fact that atmosphere–land–water connectivity is central to global C cycling, most of the prediction models did not explicitly consider atmosphere–land–water linkages in regional and global C budgets. Surface water especially rivers respond differently than uplands to environmental perturbations and have relevance in constructing a complete regional C budget (Cole et al 2007; Buffam et al 2011). Biogeochemical cycling of carbon (C) across the terrestrial–aquatic interface is. Is the movement of C controlled in a major way by the movement of water, and the processes of transformations between organic and inorganic forms are strongly influenced by the movement of water
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