[Distribution of nitrogen in the sediment of Taige south river estuary].

To characterize the distribution of nitrogen in the sediment of Taige south river estuary, column samples of sediments were collected and analyzed in April, 2012. Our results revealed that a synchronized trend existed among the levels of ammonium nitrogen (NH4(+) -N), organic nitrogen (Org-N) and total nitrogen (TN) in the surface layer of sediment. The NH4(+) -N positively correlated with TN and Org-N significantly (P < 0.05) while TN highly significantly correlated with Org-N (P < 0.01). Org-N was the major form of nitrogen, comprising 93.38% of total nitrogen (TN) averagely. Both horizontal and vertical distribution of nitrogen in sediments apparently changed along the distance to stream outlet. In the horizontal dimension in sediments, Org-N and TN decreased progressively as forwarding into the lake in the extending direction of the main stream, while showed a "W"-type fluctuation in the diverged direction away from the main stream. The level of NH4(+) -N decreased rapidly within 100 m to the stream outlet and remained constantly at a lower level beyond 100 m. However, the level of nitrate nitrogen (NO3(-) -N) stabilized within 0-800 m and increased greatly beyond 800 m. In the vertical dimension in sediments, the level of NH4(+) -N increased with increasing depth. As the distance to the stream outlet increasing, the enrichment of NO3(-) -N was enhanced in surface layers rather than in lower subsurface layers. Alternatively, the enrichment of Org-N and TN were reduced in surface layers but enhanced in subsurface layers.