Seasonal nutrient chemistry in mountainous river systems of tropical Western Peninsular India

Nutrient chemistry was studied in three mountainous rivers (Mandovi, Zuari and Netravati), across western peninsular India (WPI) during south-west monsoon (SWM), post-monsoon and pre-monsoon seasons of year 2011–2012. Nutrients in rainwater were dominated by dissolved inorganic nitrogen (DIN) and urea, dependent upon industrial emissions and the rainfall location. Nutrients in river water were enriched with DIN and Si(OH)₄ as compared with (Formula presented.) during the SWM season. During pre-monsoon, the river water was enriched with dissolved organic nitrogen (DON), whereas enrichment of a particular nutrient species was not consistent during the post-monsoon season in all three studied river systems. Nutrients exports to the estuarine water were dependent upon the geomorphological feature of river catchment and on prevalent anthropogenic activities. The significant observed contribution of DON to total dissolved nitrogen in Mandovi (62%), Zuari (83%) and Netravati (69%) is important, in view of alterations in biogeochemical processes of adjacent Arabian Sea. Furthermore, the yield of nutrient such as (Formula presented.) was found to be a function of runoff per catchment area in studied river systems, is comparable with other tropical rivers of world, which highlights the importance of mountainous rivers along WPI in their contribution to the Global riverine nutrient flux.