Export of particulate organic carbon by the mountainous tropical rivers of Western Ghats, India: Variations and controls

This study aimed to investigate the spatiotemporal variability in Particulate Organic Carbon (POC) contents, to estimate the flux and identify environmental controls on POC sources and transport characteristics across the Western Ghats (WG) region using the measured data from 70 coastal rivers. The averaged value of organic carbon (OC) in the particulate samples and the mean POC concentration throughout the WG region are 3.24%, and 2.86 mg l−1, respectively. In order to identify the source of POC, we classified the samples based on the total suspended matter (TSM) classes and the results revealed that litter/riparian (42.5%) pools are the largest source of organic matter, followed by autochthonous (36%) and soil (21.5%) for the WG region. However, locally autochthonous sources contribute exceptionally to POC pools, indicating a favorable environmental condition for the growth of algae and phytoplankton. The POC export rates suggest that within the WG region, the POC yields of the Deccan Trap (DT) and the Western Dharwar Craton (WDC) blocks are about two times higher than that of the Southern Granulite Terrain (SGT) region. With POC yield of 7.0 g m−2 yr−1, this region exports 0.79 Tg C (~ 0.5% of the global POC) to the Arabian Sea annually. The POC flux of the WG region (covering 0.25% of Asia's land area) is approximately 1.0% of Asia's riverine POC flux to the ocean.  Land-use & land-cover, climate, topography, and sediment erosion seems to be determining the local variability in sources to POC pools and fluxes.

 

S. Kiran Kumar Reddya external linkHarishGuptab external linkUpendraBadimelac external linkD. VenkatReddya external linkRama MohanKurakalvaa external linkDevenderKumara external link;Science of The Total Environment external link, Volume 751 external link, 10 January 2021, 142115; 

https://doi.org/10.1016/j.scitotenv.2020.142115 external link