Oxygen uptake and denitrification in soil aggregates
Oxygen uptake and denitrification in soil aggregates
复制标题
土壤团聚体的吸氧和反硝化
DOI：
10.1007/s00707-017-2042-x
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发表时间：
2017
期刊：
影响因子：
2.7
通讯作者：
Bocking C
中科院分区：
文献类型：
--
作者：
Bocking C
提出了农业土壤中细菌摄氧量的数学模型，目的是预测发生反硝化的厌氧区域。在氧气供应充足的环境中，微生物通过正常的呼吸消耗氧气。当局部氧浓度低于阈值水平时，可能会发生反硝化作用，导致一氧化二氮的释放，一种导致全球变暖的有力因素。提出了一个二维模型，其中一个或多个圆形土壤团聚体位于规定盛行氧浓度的地面以下一定距离。反硝化水平是通过计算任何厌氧核的面积来估计的，厌氧核可能在团聚体的内部发育。通过渐近分析，首先计算了团粒土及其周围的氧扩散系数比较小的团粒土在整个模型土壤中的氧分布。其次，采用边界元法对具有一个或多个微生物热点且扩散比任意的非团聚土进行数值研究。对多个聚集体的计算表明了一种遮蔽效应，即一些聚集体比它们的邻居吸收的氧气少。对于代表团聚土的无限规则三角形网络，表明存在使总厌氧核心面积最小的最佳团聚间距。
A mathematical model of oxygen uptake by bacteria in agricultural soils is presented with the goal of predicting anaerobic regions in which denitrification occurs. In an environment with a plentiful supply of oxygen, micro-organisms consume oxygen through normal respiration. When the local oxygen concentration falls below a threshold level, denitrification may take place leading to the release of nitrous oxide, a potent agent for global warming. A two-dimensional model is presented in which one or more circular soil aggregates are located at a distance below the ground level at which the prevailing oxygen concentration is prescribed. The level of denitrification is estimated by computing the area of any anaerobic cores, which may develop in the interior of the aggregates. The oxygen distribution throughout the model soil is calculated first for an aggregated soil for which the ratio of the oxygen diffusivities between an aggregate and its surround is small via an asymptotic analysis. Second, the case of a non-aggregated soil featuring one or more microbial hotspots, for which the diffusion ratio is arbitrary, is examined numerically using the boundary-element method. Calculations with multiple aggregates demonstrate a sheltering effect whereby some aggregates receive less oxygen than their neighbours. In the case of an infinite regular triangular network representing an aggregated soil, it is shown that there is an optimal inter-aggregate spacing which minimises the total anaerobic core area.
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