pH值对白洋淀沉积物氮磷释放的影响

目的]研究白洋淀水体在不同pH值条件下沉积物-水界面氮磷营养盐交换规律,为白洋淀富营养化的治理提供技术依据。方法]利用实验室静态模拟法,在沉积物柱状样上方加入一定pH值的上覆水,每天测定水中总氮、氨氮、总磷、总可溶性磷的浓度,并计算各营养盐的释放速率。结果]中性条件下,总氮、总磷的释放速率最小,分别为33.08和-1.21 mg/(m2.d);酸性和碱性条件下,氮磷释放速率都有所增加,尤其是强酸和弱碱性水体中总氮释放速率分别为53.56和57.11 mg/(m2.d),明显地促进了氮的释放;强酸和强碱性条件下,总磷释放明显,尤其强碱性条件下其释放速率倍增,为3.39 mg/(m2.d),而强酸和弱碱性水体中其释放速率分别为1.13和0.18 mg/(m2.d)。研究结果还显示,不同pH值下,总氮与氨氮、总磷与总可溶性磷的累积释放量有显著相关性。结论]pH值对沉积物-水界面氮磷营养盐的交换有显著影响,酸、碱水体都会促进沉积物中氮磷的释放,控制水体的酸碱度能有效抑制沉积物对水体的二次污染。

Effect of the pH Value on the Nitrogen and Phosphorus Release from the Sediment Baiyangdian

Objective]The technical basis of the eutrophication-controlling of the Baiyangdian water-body was provided through the research on the effect of the different pH values on the exchange law of the nitrogen and phosphorus in the interface between sediment and water.Method]By means of the static simulation method in laboratory,the overlying water with certain pH value was added from the top of the column sample of sediment and the concentration of total nitrogen,ammonia nitrogen,total phosphorus,total soluble phosphorus in the water was tested every day and then the release rate of nutrients was calculated.Results]Under the neutral condition,the release rate of total nitrogen and total phosphorus was the minimum,with 33.08 and-1.21 mg/(m2·d),respectively.Under the condition of acidic and alkaline,the release rate of nitrogen and phosphorus was increased,particularly under the condition of strong acid and weak alkaline the release rate of total nitrogen was 53.56 and 57.11 mg/(m2·d),indicating that the nitrogen-releasing was obviously promoted.Under the condition of strong acid and strong alkaline,total phosphorus was significantly released,especially under the condition of strong alkaline,its release rate was doubled with,3.39 mg/(m2·d) and under the condition of strong acid and weak alkaline its release rate was 1.13 and 0.18 mg/(m2·d),respectively.The results also showed there were significantly correlation between total nitrogen and ammonia nitrogen,between total phosphorus and total soluble phosphorus in the accumulation of their release under the different pH values.Conclusion]The pH value had the significant effects on exchange of nitrogen and phosphorus in the interface between sediment and water,the release of nitrogen and phosphorus from the sediment would be promoted in the acid or alkaline water-body.Thus,the control of the pH value of water body could effectively inhibit the secondary pollution of sediment to water-body.