Nutrients And Organic Carbons In River Waters Of The Third Pole

Abstract The water quality of the river basins in the Third Pole has a direct impact on the well-being of millions of people. Rivers are critical bonds for nutrients, such as organic carbon and nitrogen cycles, in the aquatic, terrestrial, and atmospheric environments. In this chapter, riverine organic carbon and nitrogen exports in nine large rivers on the Tibetan Plateau (TP)—the “water tower of Asia”—are introduced. Compared with the world average, the concentrations of dissolved organic carbon (DOC, 1.16 mg L−1) are at the low end, which is likely because of the low temperature and unproductive land vegetation environments. However, the average concentrations of dissolved organic nitrogen (DON 0.35 mg L−1) in this region are close to the world average. It is noticeable that, despite its dominant pristine environment, discharge from agricultural activities and urban areas has raised riverine N export. In addition, the DOC/DON ratio (C/N, ~6.5) was much lower than the global average, indicating that DOC in the rivers of the TP might be more bioavailable. Only a few studies on persistent organic pollutants (POPs) have been carried out in rivers of the Third Pole region. Nevertheless, there are few datasets to understand the levels and spatial distribution of these pollutants over the region. The concentration of POPs in the Koshi River basin was much higher than that in the remote areas and it was comparable to rivers in remote parts of India, however, much lower levels were observed than in the rivers in polluted areas of India. Furthermore, total suspended/insoluble particles in rivers are an emerging area of interest in river system monitoring as carriers of water pollutants. However, there is scant information on this matter in the Third Pole region. Insufficient measuring systems and lack of attention to total suspended solids and water turbidity has rendered inadequate information about pollution loads and water quality, and hence this has caused a severe impact on health, environment, and ecosystem.