白洋淀湖泊湿地中氮素分布的初步研究

湿地中氮素的空间分布在一定程度上反映了湿地环境变化的进程。对白洋淀3个典型淀区沉积物、孔隙水和上覆水中有机质和氮素进行分析,结果表明,白洋淀湖泊湿地沉积物中的有机质和全氮含量在垂直分布上表现出较好的一致性,均随深度增加而减少;但有机质和全氮分布存在空间差异性,英家淀的有机质和全氮含量均高于小杨家淀和小鸭淀;沉积物在6 cm深处,小杨家淀和小鸭淀沉积物中全氮出现一次低值,而所有采样点孔隙水中NH4 -N浓度都在此处出现一个峰值,表明6 cm深度可能是白洋淀湖泊湿地微生物降解有机氮的一个活跃区;芦苇湿地上覆水中NH4 -N和NO3--N含量都高于宽阔湖面水体,说明植被的生长不仅会促进底质有机氮的降解,其自身分泌的代谢产物及残枝败叶的腐烂也会增加水体中各种形态氮的含量,增加对水体中各种氮素的滞留,在芦苇湿地区对水面漂浮物的打捞和对芦苇的及时收割是减少湖泊湿地氮素输入的一种有效途径。

Research of Nitrogen Distribution in Baiyangdian Wetland

The spatial distribution of the nitrogen could reflect the course of the environmental change in the wetland to a certain extent.The content of the organic matter and the total nitrogen in the sediment,pore water and overlying water were analyzed for the three typical areas in Baiyangdian wetland.Results showed that the vertical distribution of the organic matter and the total nitrogen in sediment were all gradually decreases from upper to the lower,and the horizontal distribution of them in surface soil were distinctly different.There was a lower content of the total nitrogen and a higher content of the NH 4-N at 6 cm in sediment.It showed that 6 cm in sediment was an activity area of degradation organic nitrogen in Baiyangdian wetland.The content of NH 4-N and NO-3-N in upper water of bulrush area was higher than openness lakeland.The results implied that the hydrophyte in wetland could accelerate nitrogen liberation and increase nitrogen settling.At the same time,the metabolite and relict from hydrophyte could increase the nitrogenous concentration in water.So,the harvesting and refloatation was a necessary measure to reduce the nitrogen input.