Temporal and spatial variation of nitrogen and phosphorus and eutrophication assessment for a typical arid river - Fuyang River in northern China

Based on water quality surveys over 2 years (July to December, in 2014 and 2015) in a typical arid river in northern China the Xingtai segment of the Fuyang River basin the variation of nitrogen (N) and phosphorus (P) was analyzed. The extent of water eutrophication of this segment was also assessed using a universal index formula for eutrophic evaluation and a logarithmic power function. The results showed that the average concentration of total N (TN) was 27.2 mg/L (NH3-N, 63.5%), total P (TP) was 2.0 mg/L (solution reactive phosphorus, 68.8%). Temporal and spatial variations of N and P in this segment were observed. Concentrations of N and P in the arid season were higher than those in the rainy season. Spatially, the N and P concentrations followed the same trend; i.e., higher in the city segment than in the suburbs, and decreasing along the river. The water eutrophication in the studied segment reached extremely high levels at all times (eutrophication index >76.3). Spatially, its trend was clearly linked with N and P. Water shortage, pollution accumulation and a weak self-purification function are the main reasons for the prominent eutrophication in this segment. (C) 2016 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.