滇池沉积物铵态氮的时空变化特征研究

SPATIAL AND TEMPORAL VARIATIONS OF AMMONIUM NITROGEN IN SEDIMENTS OF LAKE DIANCHI,CHINA

沉积物在湖泊氮、磷循环和水体富营养化过程中起着重要作用。本研究应用GPS定位技术,于2003年5月至2004年5月,对滇池海埂、斗南、罗家村、新街、昆阳等5个代表性样点沉积物铵态氮含量进行为期1 a的动态监测,全面分析了滇池不同区域、不同层次、不同时期沉积物铵态氮的动态变化特征。结果表明,滇池沉积物铵态氮平均含量为74.57 mg kg-1,全湖沉积物铵态氮平均含量年变化范围是45.55~170.1mg kg-1。沉积物铵态氮因季节变化其变化幅度很大,各区域沉积物铵态氮含量总体趋势夏季高、冬季低,但不同位点变化高峰和趋势不同。不同层次沉积物铵态氮含量变化随季节而变化,夏季为表层（0~5 cm）〉中层（5~10 cm）〉底层（10~20 cm）,冬季为中层〉表层和底层。表层、中层、底层沉积物铵态氮含量的变化范围分别为18.71~172.9mg kg-1、29.55~192.2mg kg-1、19.93~123.8mg kg-1。各区域沉积物铵态氮平均含量以罗家村最高,斗南最低。沉积物铵态氮与水体铵态氮、水体pH呈显著正相关,与沉积物有效磷呈显著负相关,暗示了沉积物铵态氮是水体氮的源和库,并影响着沉积物中磷的释放。

Sediments play an important role in nitrogen（N） and phosphorus（P） cycling and eutrophication in lakes.Spatial and temporal variations of ammonium nitrogen（NH＋4-N） in sediments were monitored for one year（May 2003-May 2004） at 5 sampling sites（Haigeng,Dounan,Luojiacun,Xinjie and Kunyang） typical of Lake Dianchi with the aid of the GPS technology,for analysis of characteristics of dynamic variations of NH＋4-N in sediments of different depth,different times and different regions of the lake.Results show that the NH＋4-N contents in the sediments averaged 74.57mg kg-1 and varied in the range of 45.55~170.1 mg kg-1 within a year.It varied sharply with seasons,showing a general trend of being high in summer and low in winter,but the trend differed slightly from site to site.NH＋4-N contents in sediments also varied significantly with depths,showing a trend of surface（0~5cm） middle（5~10cm） bottom（10~20cm） in summer and of middle surface bottom in winter.In three layers of sediments it varied in the range of 18.71~172.9 mg kg-1,29.55~192.2 mg kg-1 and 19.93~123.8 mg kg-1,separately.In terms of mean NH＋4-N content,Luojiacun was the highest and Dounan was the lowest.NH＋4-N in the sediments showed an extremely significant positive correlation with NH＋4-N in and pH of the waterbody,but a significant negative correlation with available-P in the sediments,which indicates sediment NH＋4-N is the source and sink of NH＋4-N in the waterbody and influence release of phosphorus from the sediments.