Samples from several major world rivers were analyzed for their particulate nitrogen (PN) contents, C/N ratios, and total particulate amino acid (TPAA) contents. The results show a global PN transport of 33 × 1012g N yr−1, more than 80% of which occurs in rivers carrying high suspended matter concentrations such as the Ganges, Brahmaputra, Mekong, and Huanghe. Quantitatively, nitrogen transported in the particulate fraction exceeds that reported for dissolved inorganic nitrogen. The bulk of the PN transport is associated with material having relatively low C/N ratios and low TPAA contents. TPAA accounted for about 20% of the total PN transport. Although natural processes leading to high rates of erosion in Asian rivers might have partly contributed to the observed PN transport pattern, our results suggest that human activities such as deforestation and increased use of nitrogen fertilizer in their drainage basins are also an important factor. The biogeochemical nature of the remaining 80% is only poorly known, but should be of relevance in studying the response of estuaries and coastal seas to human activities in the terrestrial environme
展开▼
