Relationship between catchment characteristics and forms of nitrogen in Cao-E River Basin, Eastern China

• Published in: 环境科学学报（英文版） 2009, Vol.21 (4), p.429-433
• Main Authors: JIN Shuquan, LU Jun, CHEN Dingjiang, SHEN Yena, SHI Yiming
• Format: Article
• Language: English
• ISSN: 1001-0742
• DOI: 10.1016/S1001-0742(08)62287-1

X1; The distribution of different nitrogen forms and their spatial and temporal variations in different pollution types of tributaries or reaches were investigated. Based on the catchments characteristics the tributaries or reaches can be classified into 4 types including headwater in mountainous areas (type I), agricultural non-point source (NPS) pollution in rural areas (type II), municipal and industrial pollution in urban areas (type III), and combined pollution in the main stream (type IV). Water samples were collected monthly from July 2003 to June 2006 in the Cao-E River basin in Zhejiang, Eastern China. The concentrations of NO3-N, NH4+-N, and total nitrogen (TN) were measured. The mean concentrations of NO3-N were in the order type IV > type II> type III > type I, whereas, NH4+-N, total organic nitrogen (TON), and TN were in the order type III > type IV > type II> type I. In headwater and rural reaches, CNO3-N was much higher than CNH4+-N. In urban reaches, TON and NH4+-N were the main forms, accounting for 54.7% and 32.1% of TN, respectively. In the whole river system, CNH4+-N decrease with increasing distance from cities, and CNO3-N increased with the increasing area of farmland in the catchments. With increased river flow, the CNO3-N increased and the CNH4+-N decreased in all types of reaches, while the variations of CTON and CTN were different. For TN, the concentration may be decreased with the increase of river flow, but the export load always increased.