[Distribution characteristics of nitrogen and its source in core sediments from Pearl River Estuary]

Based on the measurement of the concentration of nitrogen in four core sediments from Pear River Estuary, the forms and the depth-dependent changes characteristics of nitrogen were studied, and the possible sources of nitrogen in the sediments were discussed. The results indicate that the content of total nitrogen ranged from 850.62mg/kg to 2 340.85mg/kg, with mean content of 1 502.73mg/kg. There is a general tendency for an upward increase in core sediments, which is more evident in the middle than in two ends. Organic nitrogen had a range of content from 655.42mg/kg to 2 029.86mg/kg, with mean content of 1 187.86mg/kg. And the content of organic nitrogen decreases gradually with the increase of depth or lower in the middle than in two ends. The content of NH4-N was relatively high, ranging from 47.59mg/kg to 739.61mg/kg, with mean content of 271.69mg/kg, and increases obviously with the increase of depth. The TOC/TN ratios were most between 5 and 17, which show organic matter is the mixture of aquatic and terrestrial sources. The total nitrogen has distinct synchronization phenomenon with the organic nitrogen in sedimentation course,but has little relativity with the NH4-N. There is large difference of synchronization phenomenon between total nitrogen and NH4-N at different sites.