外加氮源对滇池沉积物氮矿化影响的研究

采用连续培养法,在淹水条件下研究了添加外源氮对滇池沉积物氮矿化过程的影响.结果表明,在本研究条件下,添加水生植物残体或无机氮,均未改变沉积物氮矿化的总体趋势,表现为培养前期矿化量迅速升高并达到峰值,之后逐渐下降.各处理累积氮矿化量最大值为722.34~625.67mg/kg,约占总氮的10.5%~20.3%,与土壤相比,具有较大的矿化潜能.外加水生植物(孤尾藻,芦苇)残体的处理约在21d达到累积氮矿化量的峰值,比原沉积物分别增加了15.9%和9.3%.外加水生植物(孤尾藻,芦苇)残体和无机氮的处理比仅添加水生植物残体的处理累积氮矿化量达到峰值的时间晚一周,其最大累积氮矿化量分别减少了7.5%,9.8%和8.3%.运用Two–pool模型对试验结果进行了非线性回归拟合,通过参数和实际应用可能性剖析,Two–pool模型能较为准确地描述沉积物氮矿化过程.

Effect of supplying N on the nitrogen mineralization of Dianchi Lake sediment

Effects of exogenous nitrogen (N) addition on the N mineralization of Dianchi Lake sediment were investigated using the method of waterlogged incubation. Basic trend of N mineralization in the lake sediments did not change under the conditions of adding aquatic plants residue or inorganic N. At the beginning of experiment the amount of the mineralized N increased rapidly to their peak values, and then decreased gradually. The cumulative maximum amounts of mineralized N were from 722.34 to 625.67mg/kg, which account for 10.5%~20.3% of their total N. The potential N mineralization ability of lake sediment was higher than that of soil. The peak values of the cumulative amount of mineralized N of the sediments adding aquatic plants residue were reached after 21 days, which was increased by 15.9% and 9.3% compared with the original sediment. The time of the peak values of N mineralized from the sediments adding aquatic plants residue and inorganic N was a week later than that of adding aquatic plants residue only, and the cumulative amounts of mineralized N were reduced 7.5%, 9.8% and 8.3%, respectively. The Two-pool model was selected to fit the experimental data using a non-linear regression procedure. The Two-pool model was the one that could appropriately fit the process of organic N mineralization in all studied sediments.