An Inventory on the Phosphorus Flux of Major Indian Rivers

The biogeochemical cycles of phosphorus in rivers are intimately linked to the processes that occur in terrestrial ecosystems. Riverine networks hold a crucial role in the transfer of nutrients from the land and atmosphere to the coastal oceans and often act as pool for numerous inorganic and organic compounds. Biogeochemical transformation of elements in river network is extensively influenced by catchment alteration and anthropogenic inputs. By means of the rising consciousness of human impact on the excellence of rivers, emphasis is given on rivers, as an ecosystem by itself and also on the river-coast continuum. In this study, the major forcing functions that affect the riverine composition of phosphorus have been examined, in Indian context. An attempt has been made to study and inventorize phosphorus flux from major Indian rivers. Relatively high concentrations of dissolved PO^3-₄ (dissolved inorganic phosphorus - DIP) are observed in few of the Indian rivers, which may be due to modifications in river catchment. The flow of DIP and particulate inorganic phosphorus to the coastal ocean from Indian rivers is estimated to be about 190 x 10³ tonnes year^-1 and 1367 x 10³ tonnes year^-1 respectively. Suspended load is significant in Indian rivers and its cumulative flux is in the order of 1450 x 10⁶ tonnes year^-1. The DIP concentration in the Indian rivers is more than twice the concentration observed for the other rivers in the world. Such increased nutrient input into the riverine system reflects the imbalances and alterations in terrestrial sources. Thus, the quantity and quality of nutrient input to the rivers need to be monitored to cope with the existing and future climatic and environmental changes.