[Pollution Characteristics and Nitrification and Denitrification Potential of Superficial Sediments from Streams in an Urban-Rural Fringe].

From May 2015 to June 2016, seasonal sediment samples were collected from three headwater streams in the urban-rural fringe of Hefei, Chaohu Lake basin, China. The nitrogen pollution characteristics of sediments were preliminarily investigated for the three streams. Three metrics, that is, potential nitrification rate (PNR), areal nitrification rate (ANR) and rate of denitrification were quantitatively determined, and their spatial and temporal variations were discussed subsequently. Moreover, the relationship between PNR, ANR or denitrification rate and a list of environmental factors was discriminated by using partial least-squares regression analysis. Results showed that:① Guanzhenhe Distributary was the most polluted stream with a mean content of 4516.39 mg·kg for TN, which was 2.56 and 1.36 times higher than those of Modian Stream and Taochong Stream, respectively. Similarly, the highest values for NH-N and NO-N emerged in Guanzhenhe Distributary while the lowest existed in Modian Stream. ② There were distinct seasonal variations in PNR and ANR, namely, the maximum values emerged in summer, minimum in winter, and almost equivalent in spring and autumn. And the arrangement in order for PNR and ANR was Taochong Stream > Modian Stream > Guanzhenhe Distributary. ③ The mean rate of denitrification in Guanzhenhe Distributary was 10.59 mg·(kg·h), which was 3.16 and 1.75 times higher than those in Modian Stream and Taochong Stream, respectively. In addition, both denitrification rate and denitrification activity in summer were higher than those in spring for the three streams. ④ According to the variable importance plot (), ANR, PNR and rate of denitrification were almost all significantly correlated with such physical and chemical factors as pH, OM, NH-N, NO-N, TN and TP in sediments for the three streams.