SPATIAL-TEMPORAL DISTRIBUTION CHARACTERISTICS AND INFLUENCING FACTORS OF CONVERTIBLE NITROGEN IN SURFACE SEDIMENTS OF THE POYANG LAKE
To study the distribution of nitrogen forms in sediments of the Poyang Lake,this paper divided Poyang Lake into three parts:the northern lake area,the central lake area,and the river inflow area.The overlying water and sediments were collected from different regions during the wet season,normal water period,and dry season.The ion exchangeable nitrogen(IEF-N),weak acid extractable nitrogen(WAEF-N),strong alkali extractable nitrogen(SAEF-N),and strong oxidant extractable nitrogen(SOEF-N)in sediments were extracted by graded leaching method,and the correlation between various forms of convertible nitrogen in sediments and physical and chemical properties of sediments was analyzed.The results showed that the TN content of sediments was 2.05 to 8.91 g/kg in the wet season,1885.71 to 4727.27 mg/kg in the normal season,and 480.79 to 3933.00 mg/kg in the dry season,which was the highest in the wet season.The contents of four kinds of convertible nitrogen in sediments were significantly different in different periods;and the content of SOEF-N was the highest in the three periods,inferring SOEF-N was the main species of convertible nitrogen.Spatially,the TN content of the Poyang Lake sediments was in the sequence of the river inflow area＞the northern lake area＞the central lake area;the spatial distribution of convertible nitrogen content in sediments was related to the water level,and the spatial distribution of four kinds of convertible nitrogen content varied greatly in different periods.The contents of various forms of nitrogen in sediments had a great correlation with the physical and chemical properties of sediments,and were mainly affected by climate and environment.
the Poyang Lakesedimenttotal nitrogentransformable nitrogenspatial and temporal distribution
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