鄱阳湖表层沉积物可转化态氮时空分布特征及影响因素

SPATIAL-TEMPORAL DISTRIBUTION CHARACTERISTICS AND INFLUENCING FACTORS OF CONVERTIBLE NITROGEN IN SURFACE SEDIMENTS OF THE POYANG LAKE

为研究鄱阳湖沉积物氮形态的分布,将鄱阳湖分为北部湖区、中心湖区、河流入湖区3部分,于丰水期、平水期、枯水期对不同区域进行上覆水及沉积物的采集,利用分级浸取法对沉积物中的离子交换态氮(IEF-N)、弱酸可浸取态氮(WAEF-N)、强碱可浸取态氮(SAEF-N)、强氧化剂可浸取态氮(SOEF-N)进行提取,并对沉积物各形态可转化态氮与沉积物理化性质进行相关性分析。结果表明:丰水期沉积物TN含量为2.05~8.91 g/kg,平水期沉积物TN含量为1885.71~4727.27 mg/kg,枯水期沉积物总氮(TN)含量为480.79~3933.00 mg/kg,总体表现为丰水期含量最高;沉积物中4种可转化态氮含量在不同时期有明显差异,最显著的特征表现为3个时期SOEF-N含量均表现为最高,可见可转化态氮以SOEF-N为主。空间上,鄱阳湖沉积物TN含量表现为河流入湖区>北部湖区>中心湖区;沉积物可转化态氮含量的空间分布与水位变化有关,在不同时期4种可转化态氮含量的空间分布存在较大差异。沉积物中各形态氮含量与沉积物的理化性质有极大相关性,并且多受到气候环境等因素的影响。

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.