Assessing dissolved inorganic nitrogen flux in the Yangtze River, China: Sources and scenarios

Abstract

This study gives a thorough assessment of the occurrences of dissolved inorganic nitrogen (DIN) in the Yangtze River in the past half century. The results have shown that nitrogen fertilizer, a major DIN source, has been replaced by domestic sewage in the last decade, which has dramatically driven up DIN loads in the Yangtze. DIN concentrations showed a rapid increase from <0.5mgL-1 in the 1960s to nearly 1.5mgL-1 at the end of the 1990s. Since then DIN has remained steady at ca. 1.6-1.8mgL-1. A significant relationship between the historical DIN record at the downstream gauging station (Datong) and nitrogen (N) sources in the Yangtze River basin is established using principal components ana..