Abstract Agricultural runoff is a major contributor of nutrients to downstream freshwater and marine waters that, in turn, cause harmful algal blooms. “Wetlaculture,” a new landscape management approach defined as “integrating wetland nutrient removal with recycling of these nutrients to agriculture,” has the dual goals of reducing the need for fertilizer in agriculture while mitigating fluxes of nutrients to downstream aquatic ecosystems with created or restored wetlands. A mesocosm compound consisted of twenty-eight 380 L, 1-m2 tubs filled with local hydric soil was initiated in mid-2016 near a highly eutrophic Buckeye Lake in central Ohio, USA, to investigate the wetlaculture approach in an experimental fashion. In October 2016, each mesocosm tub was inserted in the ground and planted with the sedge Schoenoplectus tabernaemontani. The mesocosms were assigned to four hydrologic treatments involving two water depths and two hydraulic loading rates (HLRs). Nearby river water containing significant agricultural runoff was added weekly into a water feed tank system to provide weekly hydraulic loadings to the mesocosms. Inflow and outflow water samples from each wetland mesocosm were collected and analyzed for five species of nitrogen and phosphorus. By August 2019, 17 plant species, including the planted S. tabernaemontani, were present in the wetland mesocosms. The wetland mesocosms soon became nutrient sinks with average removal efficiencies of total phosphorus (TP) and total nitrogen (TN) of 38 ± 2.5% and 44 ± 1%, respectively, through the three-year experiment. The combination of a high HLR (30 cm week−1) and 10 cm of standing water achieved the best nitrogen removal efficiencies while highest phosphorus removal occurred with the combination of a high HLR (30 cm week−1) and no standing water. This paper discusses the following integrative findings: • Seasonal flooding had positive impacts on removal efficiency of NOx and a negative impact on the removal efficiency of TP and TKN. • No standing water resulted in a higher removal efficiency of TP and TKN than standing water, results consistent with previous studies. • Macrophyte plant community richness was influenced more by water depth than by hydraulic loading rate. Wetlands with 10 cm of standing water instead of saturated soils developed lower species richness but were more dominated by true wetland (OBL and FACW) species. • Study scale does matter. Annual nutrient accumulation rates in the mesocosms (1 m2) soils were lower than in the full-scale (10,000-m2) multi-year wetlands at the nearby Olentangy River Wetland Research Park (ORWRP) in central Ohio. Annual accumulation rates of phosphorus and nitrogen in the full-scale wetlands ranged from 3.3 to 3.5 g-P m−2 yr−1 and 16.4 to 19.5 g-N m−2 yr−1, while in our mesocosms, the annual rates ranged from 0.66 to 1.40 g-P m−2 yr−1 and 7.85 to 15.08 g-N m−2 yr−1. Our experimental wetland mesocosms could only function in the non-freezing months and have been in operation for only three years.

中文翻译：

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水文条件对前俄亥俄州中部沼泽地养分保留以及土壤和植物发育的影响：湿地养殖中观实验

摘要 农业径流是下游淡水和海水养分的主要贡献者，进而导致有害的藻类大量繁殖。“湿地养殖”是一种新的景观管理方法，定义为“将湿地养分去除与这些养分回收到农业相结合”，具有双重目标，即减少农业对肥料的需求，同时通过创建或恢复的方式减少对下游水生生态系统的养分通量湿地。2016 年年中，在美国俄亥俄州中部高度富营养化的七叶树湖附近启动了一个由 28 个 380 L、1 平方米的浴缸组成的中观化合物，以实验方式研究湿法养殖方法。2016 年 10 月，每个中胚层盆都插入地下并种植了莎草 Schoenoplectus tabernaemontani。中观被分配到四个水文处理，涉及两个水深和两个水力加载率 (HLR)。每周将含有大量农业径流的附近河水添加到供水罐系统中，以提供每周一次的水力负荷给中观世界。收集了每个湿地中层的流入和流出水样，并分析了五种氮和磷。到 2019 年 8 月，湿地中宇宙中存在 17 种植物物种，包括种植的 S. tabernaemontani。通过三年的实验，湿地中层很快成为养分汇，总磷（TP）和总氮（TN）的平均去除效率分别为 38±2.5% 和 44±1%。高 HLR（30 cm week-1）和 10 cm 静水的组合实现了最佳的脱氮效率，而最高的除磷发生在高 HLR（30 cm week-1）和无静水的组合中。本文讨论了以下综合发现： • 季节性洪水对 NOx 的去除效率有积极影响，对 TP 和 TKN 的去除效率有负面影响。• 无静水比静水具有更高的 TP 和 TKN 去除效率，结果与之前的研究一致。• 大型植物群落丰富度受水深的影响比受水力加载速率的影响更大。具有 10 cm 静水而不是饱和土壤的湿地物种丰富度较低，但更多地以真正的湿地（OBL 和 FACW）物种为主。• 学习规模很重要。在俄亥俄州中部附近的 Olentangy 河湿地研究公园 (ORWRP) 中，中层 (1 m2) 土壤中的年养分积累率低于全尺度 (10,000 平方米) 多年湿地。全尺度湿地中磷和氮的年积累率为 3.3 至 3.5 gP m-2 yr-1 和 16.4 至 19.5 gN m-2 yr-1，而在我们的中世界中，年累积率为 0.66 至 1.40 gP m-2 yr-1 和 7.85 至 15.08 gN m-2 yr-1。我们的实验性湿地中观世界只能在不结冰的月份运行，并且仅运行了三年。全尺度湿地中磷和氮的年积累率为 3.3 至 3.5 gP m-2 yr-1 和 16.4 至 19.5 gN m-2 yr-1，而在我们的中世界中，年累积率为 0.66 至 1.40 gP m-2 yr-1 和 7.85 至 15.08 gN m-2 yr-1。我们的实验性湿地中观世界只能在不结冰的月份运行，并且仅运行了三年。全尺度湿地中磷和氮的年积累率为 3.3 至 3.5 gP m-2 yr-1 和 16.4 至 19.5 gN m-2 yr-1，而在我们的中世界中，年累积率为 0.66 至 1.40 gP m-2 yr-1 和 7.85 至 15.08 gN m-2 yr-1。我们的实验性湿地中观世界只能在不结冰的月份运行，并且仅运行了三年。