Sorption and desorption characteristics of ammonium in the surface sediments of Lake Dianchi

In order to study the endogenous pollution characteristics of Lake Dianchi,36 samples were set in whole Lake Dianchi using the GIS exploring in 2013. Through collecting the surface sediment samples,adsorption characteristics of ammonia on surface sediments were studied and the influence of physical and chemical properties of sediments on the adsorption characteristics of ammonia was also analyzed. The results showed that the adsorption quantity of ammonia nitrogen on surface sediments of the Lake Dianchi showed a growing trend in 2 h and the adsorption rate was relatively high. After 2 h,the adsorption quantity of ammonia on surface sediments did not change with time and attain the basic balance. The maximum adsorption rate appeared during 0-5 min.An order of the average maximum adsorption rate of ammonia on sediments of different sub-lake waters was: the south of Lake Waihai the center of the lake the south of Lake Waihai Lake Caohai. An order of the average of maximum adsorbent quantity was: the center of the lake the south of Lake Waihai the north of Lake Waihai Lake Caohai. A order of the average adsorption efficiency was: the north of Lake Waihai Lake Caohai the center of the lake the south of Lake Waihai. The adsorption quantity of ammonia on sediments showed a rough linear relationship with the initial concentration of ammonia. Under a low concentration condition,a good adsorption / desorption characteristic occurred. Through comparing the concentration of adsorption / desorption of ammonia on sediments and the concentration between overlying water and sediments,the results showed that the ENC0 of ammonia in sediments was higher than that in overlying water,indicating that the ammonia had the releasing risk from sediments to overlying water. These inferred that the sediments would play a role of the water pollution"source"in a long time. As ENC0 had the positive correlation with total nitrogen and ammonium nitrogen in sediments and NAN had negative correlation with total organic matter,we recognized that the ammonia adsorbed by sediments was mainly influenced by organic matter.