Simulation Model of the Coupling between Nitrification and Denitrification in a Freshwater Sediment
Simulation Model of the Coupling between Nitrification and Denitrification in a Freshwater Sediment
复制标题
淡水沉积物硝化与反硝化耦合模拟模型
DOI：
10.1128/aem.60.9.3089-3095.1994
复制
发表时间：
1994
影响因子：
4.4
通讯作者：
N. Risgaard
中科院分区：
文献类型：
--
作者：
T. Blackburn;N. Blackburn;Kim B. Jensen;N. Risgaard
构建了一个模型来模拟研究丹麦 Vilhelmsborg 湖淡水沉积物硝化和反硝化作用的实验结果（K. Jensen、N. P. Sloth、N. Risgaard-Petersen、S. Rysgaard 和 N. P. Revsbech, Appl. Environ. Microbiol. 60:2094-2100, 1994）。当上覆水中的 O2 浓度从 10 μM 增加到 600 μM 时，模型输出忠实地反映了 O2 和 NO3- 的分布以及硝化、反硝化和 O2 消耗的速率。该模型还准确预测了硝化和反硝化的综合速率（微摩尔每平方米每小时）对氧气浓度增加的响应。当上覆水中的 O2 浓度改变时，从上覆水中扩散的 NO3- 反硝化速率 (Dw) 和沉积物内硝化作用产生的 NO3- 反硝化速率 (Dn) 的模拟速率与实验速率相对应。随着上覆水中 NO3- 浓度的变化，预测的 Dw 和 Dn 速率与实验确定的值非常相似。该模型由41层0.1毫米厚组成，其中3层代表水中的扩散边界层。需要较大的硝化和反硝化一级速率常数来完全氧化从较低沉积层扩散的所有 NH4+ 并去除大部分产生的 NO3-。除了来自下方的 NH4+ 通量之外，该模型还需要电子供体（可能是甲烷）的通量。硝化作用和反硝化作用之间的紧密耦合是通过允许反硝化作用耐受一些 O2 (∼10 μM) 来实现的，这对于重现真实数据是必要的。两个过程的空间分离（无法容忍 O2 反硝化）导致 NO3- 浓度过高和反硝化速率过低。
A model was constructed to simulate the results of experiments which investigated nitrification and denitrification in the freshwater sediment of Lake Vilhelmsborg, Denmark (K. Jensen, N. P. Sloth, N. Risgaard-Petersen, S. Rysgaard, and N. P. Revsbech, Appl. Environ. Microbiol. 60:2094-2100, 1994). The model output faithfully represented the profiles of O2 and NO3- and rates of nitrification, denitrification, and O2 consumption as the O2 concentration in the overlying water was increased from 10 to 600 μM. The model also accurately predicted the response, to increasing O2 concentrations, of the integrated (micromoles per square meter per hour) rates of nitrification and denitrification. The simulated rates of denitrification of NO3- diffusing from the overlying water (Dw) and of NO3- generated by nitrification within the sediment (Dn) corresponded to the experimental rates as the O2 concentration in the overlying water was altered. The predicted Dw and Dn rates, as NO3- concentration in the overlying water was changed, closely resembled those determined experimentally. The model was composed of 41 layers 0.1 mm thick, of which 3 represented the diffusive boundary layer in the water. Large first-order rate constants for nitrification and denitrification were required to completely oxidize all NH4+ diffusing from the lower sediment layers and to remove much of the NO3- produced. In addition to the flux of NH4+ from below, the model required a flux of an electron donor, possibly methane. Close coupling between nitrification and denitrification, achieved by allowing denitrification to tolerate some O2 (∼10 μM), was necessary to reproduce the real data. Spatial separation of the two processes (no toleration by denitrification of O2) resulted in too high NO3- concentrations and too low rates of denitrification.