Phosphorus (P) release to surface and groundwater often occurs in wetlands that were restored on former agricultural fields. We identified pore water, shallow groundwater, and plant biomass decomposition as sources of soluble reactive (SRP) and total phosphorus (TP) export to the Chicago River between 1998 and 2014 from Prairie Wolf Slough Wetland Demonstration Project (PWS), a wetland restored on a former farmed field in suburban Chicago, Illinois. We estimated the relative annual contributions of SRP from these sources to yearly discharge to the river and conducted an SRP mass balance. SRP and TP concentrations and loadings were consistently greater at the outlet compared to the inlet, suggesting PWS was a source of P. Twenty‐three grams of SRP was exported during the mass balance study. SRP concentration at the inlet accounted for less than 3% of the SRP exported annually at the outlet to the Chicago River. Plant biomass decomposition, pore water diffusion, and groundwater seepage together accounted for 85% of annual export. Twelve percent of annual SRP export remains unknown. PWS was ineffective in reducing P export, indicating an ecosystem disservice. Our study highlights the need to identify the sources of P exported from wetlands restored on farm fields to better understand the biogeochemical processes that determine whether a wetland will serve as a source or sink of P. Pre‐restoration measurement, followed by decadal‐scale post‐restoration monitoring, of source‐water and soil P are needed to evaluate the success of wetland restorations designed to sequester P from runoff.

中文翻译：

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对草原狼泥沼遗留的磷排放进行的为期16年的调查：在以前的耕地上恢复的湿地

磷（P）释放到地表和地下水通常发生在以前农田恢复的湿地中。我们将孔隙水，浅层地下水和植物生物质分解确定为1998年至2014年之间从草原狼泥沼湿地示范项目（PWS）出口到芝加哥河的可溶性反应物（SRP）和总磷（TP）的来源，以前是伊利诺伊州芝加哥郊区的农田。我们估算了来自这些来源的SRP对每年向河流排放的相对年贡献，并进行了SRP质量平衡。与进口相比，出口处的SRP和TP浓度和负荷始终较高，这表明PWS是P的来源。在质量平衡研究中，出口了23克SRP。入口处的SRP浓度每年不到出口到芝加哥河的SRP的3％。植物生物量的分解，孔隙水的扩散和地下水的渗漏一起占了年出口量的85％。SRP年度出口量的百分之十二仍然未知。PWS在减少磷出口方面没有效果，表明生态系统受到损害。我们的研究强调需要确定从农田恢复的湿地中输出的P的来源，以便更好地了解确定湿地将用作P的源或汇的生物地球化学过程。需要对源水和土壤P进行恢复监测，以评估旨在将P从径流中隔离的湿地恢复的成功性。