滇池沉积物生物有效性氮和磷的分布及相互关系

Distribution of Bioavailable Nitrogen and Phosphorus Forms and Their Relationship in the Sediments of Dianchi Lake

利用化学连续提取法,对滇池8个采样点表层沉积物中的生物有效性氮和磷的分布进行了研究,并探讨了二者间的关系.结果表明:滇池沉积物中w(TN)和w(TP)的分布特征具有显著差异,北部和南部因磷矿开采、外源污染输入导致其值较高,中部受水动力影响较大则其值相对较低;沉积物中生物有效性氮和磷包括离子交换态氮和磷(IEF-N,IEF-P)、弱酸可提取态氮和磷(WAEF-N,WAEF-P)、强碱可提取态氮和磷(SAEF-N,SAEF-P)以及强氧化剂可提取态氮和磷(SOEF-N,SOEF-P)等4种形态;各生物有效性氮对总的生物有效性氮的贡献顺序依次为w(SOEF-N)(68.1%～78.8%)>w(IEF-N)(10.1%～14.9%)>w(WAEF-N)(5.8%～8.9%)≈w(SAEF-N)(5.3%～8.7%),生物有效性磷的相对含量顺序依次为w(SAEF-P)(68.6%～75.2%)>w(SOEF-P)(23.4%～30.0%)>w(WAEF-P)(0.6%～1.8%)>w(IEF-P)(0～0.1%);生物有效性氮和磷具有正相关性,二者迁移转化的趋势可能具有一致性.生物有效性氮和磷的比值分析表明,沉积物中生物有效性氮和磷的形态差异影响氮、磷的矿化和释放速率.

The distribution of bioavailable nitrogen and phosphorus forms in eight sampling sites from surface sediments of Dianchi Lake was analyzed by chemical sequential extraction methods,and their relationships were also discussed. The results showed that the distribution of w（TP） and w（TN） varied significantly by spatial location. Due to mining of phosphorite and external pollution inputs, the contents of TP and TN were high in the northern and southern parts of Dianchi Lake. In the middle part,the contents of TP and TN were relatively low because of the influence of hydrodynamic force. The bioavailable nitrogen and phosphorus in the sediments consisted of four forms： ion exchangeable nitrogen and phosphorus （IEF-N,IEF-P）,weak acid extractable nitrogen and phosphorus （WAEF-N, WAEF-P）,strong alkali extractable nitrogen and phosphorus （ SAEF-N,SAEF-P）,and strong oxidant extractable nitrogen and phosphorus （SOEF-N,SOEF-P）. The relative contents of different bioavailable nitrogen and phosphorus forms ranked according to the following sequence： w （ SOEF-N ） （ 68. 1%-78. 8% ） w （ IEF-N ） （ 10. 1%-14. 9% ） w （ WAEF-N ） （ 5. 8%-8. 9% ） ≈ w（SAEF-N） （5. 3%-8. 7% ）,and w（ SAEF-P） （68. 6%-75. 2% ） w（ SOEF-P） （23. 4%-30. 0% ） w（ WAEF-P） （0. 6%-1. 8% ） w （ IEF-P ） （0-0. 1% ）. There was a positive correlation between bioavailable nitrogen and phosphorus forms, indicating the same trend of transfer and transformation. The ratio of bioavailable nitrogen to phosphorus in the same extractant was also analyzed; the results suggested that the different bioavailable nitrogen and phosphorus forms influenced the mineralization and release rate of nitrogen and phosphorus in the sediments.