农田排水沟渠底泥-间隙水-上覆水氮磷迁移转化规律研究

研究氮磷在底泥、上覆水以及两者间交换介质-间隙水三者之间的迁移转化规律对控制农业面源污染具有重要科学意义。本研究对降雨和无降雨情况下氮磷在沟渠底泥、间隙水和上覆水间的迁移转化规律进行了分析;同时,对扫描电子显微镜(SEM)下底泥颗粒的微观形貌进行了观测。结果表明:在水稻生长前期氮磷被吸附贮存在底泥中,中后期被再次释放出来;在整个水稻生长期内,间隙水的总氮、总磷浓度约为上覆水的3.1和6.5倍,氮主要以NH_4~+-N形式存在;在降雨过程中,沟渠底泥成为氮磷释放的源,NH_4~+-N为氮的主要迁移形态,上覆水中NH_4~+-N逐渐向NO_3~--N转化,颗粒态氮磷对TN、TP流失有较大影响;沟渠底泥颗粒表面粗糙、具有一定的微孔结构,为底泥吸附氮磷提供了条件。

Study on the migration and transformation of nitrogen and phosphorus in sediment-interstitial water-overlying water in farmland drainage ditch

Study on the migration and transformation of nitrogen and phosphorus among the sediment-interstitial water-overlying water can contribute to grasp the interception mechanism of nitrogen and phosphorus in farmland drainage ditch. In this paper, the migration and transformation of nitrogen and phosphorus through the three were studied and the sediment morphology was tested by scanning electron microscope (SEM). The results show that:the nitrogen and phosphorus are adsorbed and stored in the sediment in the early stage of rice growth, and the nitrogen and phosphorus are released in the later ice growth; during the entire rice growth, the concentration of nitrogen and phosphorus in the interstitial water are about 3.1 and 6.5 times the overlying water, which the NH₄⁺-N as the main nitrogen form of storage; in the process of rainfall, the ditch sediment as the source of nitrogen and phosphorus which provide the nitrogen and phosphorus in the interstitial water gradually migrate to the overlying water, NH₄⁺-N gradually change to NO₃^--N,and the granular TN and TP had a great influence on the loss of TN and TP in the overlying water; and the surface of sediment particles is rough and has a pore structure, that is conducive to the adsorption of nitrogen and phosphorus.