Sharifi A, Kalin L, Asce A M, Hantush M M, Asce A M, Dahlgren R A, O'Geen A T, Maynard J J
Research Associate, Univ. of Maryland, 10300 Baltimore Ave., Bldg. 007, Barc-West, Beltsville, MD 20705.
Associate Professor, Auburn Univ., 602 Duncan Dr., Auburn, AL 36849.
J Hydrol Eng. 2017 Jan 1;22(1). doi: 10.1061/(asce)he.1943-5584.0001196.
A common phenomenon observed in natural and constructed wetlands is short-circuiting of flow and formation of stagnant zones that are only indirectly connected with the incoming water. Biogeochemistry of passive areas is potentially much different than that of active zones. In the research reported in this paper, the spatial resolution of a previously developed wetland nutrient cycling model was improved in order to capture the spatial variability of concentrations and reaction rates regarding nitrogen and carbon cycles throughout active and passive zones of wetlands. The upgraded model allows for several compartments in the horizontal domain, with all neighboring compartments connected through advective and dispersive/diffusive mass transport. The model was applied to data collected from a restored wetland in California that was characterized by the formation of a large stagnant zone at the southern end of the wetland due to close vicinity of the inlet and outlet structures in the northern end. Mass balance analysis revealed that over the course of the research period, about 23.4±3.9% of the incoming total nitrogen load was removed or retained by the wetland. It was observed that mass of all exchanges (physical and biogeochemical) regarding nitrogen cycling decreased along the activity gradient from active to passive zones. Model results also revealed that anaerobic processes become more significant along the activity gradient towards passive areas.
在天然湿地和人工湿地中观察到的一个常见现象是水流短路和停滞区的形成，这些停滞区仅与进水间接相连。非活动区域的生物地球化学可能与活动区域有很大不同。在本文报道的研究中，对先前开发的湿地养分循环模型的空间分辨率进行了改进，以捕捉湿地活动区和非活动区整个氮和碳循环的浓度和反应速率的空间变异性。升级后的模型在水平域中有多个隔室，所有相邻隔室通过平流和分散/扩散物质传输相连。该模型应用于从加利福尼亚州一个恢复湿地收集的数据，该湿地的特点是由于北端进水口和出水口结构紧邻，在湿地南端形成了一个大的停滞区。质量平衡分析表明，在研究期间，湿地去除或保留了约23.4±3.9%的总氮入流负荷。观察到，氮循环的所有交换（物理和生物地球化学）量沿从活动区到非活动区的活动梯度下降。模型结果还表明，厌氧过程沿活动梯度向非活动区变得更加显著。
