滇池水-沉积物界面氮分布特点及其对控制蓝藻水华的意义

The distribution characteristics of nitrogen across water-sediment interface and its significance for controlling algal blooms in Dianchi Lake

造成水体富营养化的污染源可以分为外源和内源,当湖泊的外源得到控制以后,内源营养盐的释放仍然可以发生富营养化,甚至爆发藻类水华.研究营养物质在水-沉积物界面的地球化学行为,对于控制水体富营养化和水华爆发具有重要意义.以滇池为研究对象,测定了间隙水和上覆水中总氮(TN)、氨态氮(NH+4-N)、硝态氮(NO-4-N3-N)和有机氮(ON)的质量浓度.结果表明:①无论在草海还是外海,间隙水中TN,NH+及ON质量浓度均高于上覆水,说明底泥中的氮元素有向水体中扩散的趋势;②草海上覆水及间隙水中TN,NH+3-N质量浓度均高于外海,其受污染的程度比外海高.研究揭示了滇池底泥中氮分布区域和4-N和NO-垂直变化特征,阐明了内源氮负荷在湖泊富营养化中所起的作用.

Lakes' eutrophication become a serious environmental problem in China,and the algae bloom is the challenge of all the eutrophicated lakes.Pollution sources of eutrophication lakes include external sources and internal sources.When the external pollution sources are controlled,eutrophication will still happen because of the existence and release of inner loading nutrient in sediments.Then nutrients become the leading factor of the lakes' eutrophication.The mass concentration of total nitrogen (TN),ammonia (NH^+_4-N),nitrate (NO^-_3-N) and organic nitrogen (ON) in interstitial water and overlying water of Dianchi lake was mensurated.The results are as following:① No matter in Caohai or Waihai,the mass concentration of TN,NH^+_4-N and ON are higher in interstitial water than those in overlying water,which indicates that the nitrogen in the sediment has been releasing into the water column and play an important roll in the eutrophication process of Dianchi Lake.So more attetion should be paid to the internal pollution sources when controlling the eutrophication of Dianchi Lake.② The mass concentration of TN,NH^+_4-N and NO^-_3-N are higher in Caohai than those in Waihai,so it can be conclude that the pollution degree of Caohai is more serious than that of Waihai.The spatial distribution characteristics of nitrogen and the rolls of internal sources in lakes' eutrophication are explained clearly from the research.