沉积物不同天然有机组分对氨氮吸附特征的影响

为估算沉积物不同天然有机组分吸附态氨氮携载量．采用平衡吸附法研究西辽河沉积物不同天然有机组分对氨氮吸附特征的影响。结果表明，去除有机质后的沉积物对氨氮的吸附能力大大降低，其碳标化饱和吸附量（Гmoc）和吸附分配系数（Koc）分别为重组的55．30％和69．49％，说明有机质是影响氨氮在沉积物上吸附特征的主要因素。氨氮在轻组有机组分上的吸附以分配作用为主（Koc=85．57）；稳结态和紧结态腐殖质是形成沉积物疏松多孔团聚体结构的重要胶结物质，氨氮在重组有机组分上的吸附除分配作用外，还存在孔隙填充方式的吸附；重组有机组分中的紧结态腐殖质（胡敏素）对氨氮吸附起关键作用（Гmoc，=5857．78mg·kg-1）。轻组有机质、稳结态腐殖质和紧结态腐殖质携载的吸附态氨氮可分别按重组（Гmoc=3477．81mg·kg-1）的0．32、1．21和1．68倍估算。关键词：沉积物；天然有机组分；氨氮；吸附；碳标化吸附分配系数；碳标化饱和吸附量

Effects of Fractions of Natural Organic Matter in Sediment on Sorption Characteristic of Ammonium Nitrogen.

In order to estimate amounts of the ammonium nitrogen adsorbed by different fractions of natural organic matter in sediment, effects of fractions of natural organic matter in sediment on sorption of ammonium nitrogen were investigated by batch experiments of equilibrium adsorption. Results show that sorption capacity of the sediment reduced dramatically after its organic matter was removed, with normalized sorption capacity and partition coefficient equaling only to 55.30% and 69.49%, respectively, that of the heavy fraction of organic matter, indicating that organic matter is a main factor affecting sorption of ammonium nitrogen on sediment. However, sorption of ammonium nitrogen in the light fraction of organ- ic matter was dominated by distribution （ Koc = 85.57 ）. Stably cmnbined humus and tightly combined humus were impor- tant adhesive substances in the formation of loose and porous aggregate structure of the sediment. In the heavy fraction of organic matter, besides the mechanism of distribution, sorption of ammonium nitrogen was controlled by the mechanism of pore-filling （Гmoc =3 477. 81 mg. kg-l ）. Furthermore, tightly combined humus （humin） played a leading role in sorp- tion of ammonium nitrogen （Гmoc= 5 857.78 mg. kg-1 ）. Consequently, in estimating amount of the ammonium nitrogen adsorbed by the light fraction of organic matter, stably combined humus and tightly combined humus, it is advisable to count it as 0. 32, 1.21 and 1.68 times, respectively, of that by the heavy fraction of organic matter.