Irrigation return water from container plant nurseries often contains elevated levels of nitrogen (N) and phosphorus (P). Floating treatment wetlands (FTWs) are one solution for removing nutrients from irrigation return flow. This study assessed how FTW planting strategy (monoculture vs mixed planting) influenced removal of N and P. Tanks containing FTWs received water with ∼22.3 N and 3.12 mg·L^–1 P water-soluble fertilizer every 7 days for two, 8-week experiments. Experimental treatments were a control (open water); monoculture plantings (Iris ensata ‘Rising Sun’, Canna ×generalis ‘Firebird’, Agrostis alba, Carex stricta, or Panicum virgatum); or mixed plantings [2 mixtures: partial (monocots only) or a complete mixture of all plants]. For FTWs established in all treatments (except control), N and P removal from solution was additive, with a similar mass of N and P removed. However, when assessing nutrient uptake within plant tissues in FTWs, Panicum virgatum performed better (absorbed more N) within mixtures, a possible synergistic effect, while Iris ensata ‘Rising Sun’ performed poorly (fixed less N) within the complete mixture, a possible antagonist effect. Nutrient assimilation within plant tissues did not correlate with overall remediation performance for monocultures or mixtures, as tissue accumulation varied by nutrient and mixture.

中文翻译：

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漂浮处理湿地内单一栽培和混合物种种植对营养的比较。

来自集装箱厂苗圃的灌溉回水通常含有较高水平的氮（N）和磷（P）。浮动处理湿地（FTW）是从灌溉回流中去除养分的一种解决方案。这项研究评估了FTW的种植策略（单种种植与混合种植）如何影响氮和磷的去除。装有FTW的储罐每7天收到约22.3 N和3.12 mg·L ^–1 P水溶性肥料的水，持续2、8周实验。实验处理是对照（开放水）；单一种植的植物（鸢尾鸢尾'旭日'，美人蕉× '火鸟'，Agrostis alba，Carex stricta或Panicum virgatum）; 或混合种植[2种混合物：部分（仅单子叶植物）或所有植物的完全混合物]。对于所有处理中建立的FTW（对照除外），从溶液中去除氮和磷是累加的，去除了类似质量的氮和磷。然而，当评估FTWs中植物组织内的养分吸收时，Panicum virgatum在混合物中表现更好（吸收更多的N），可能产生协同作用，而鸢尾鸢尾的“ Rising Sun”在整个混合物中表现不佳（固定的N）。拮抗作用。植物组织内的养分吸收与单一培养物或混合物的整体修复性能不相关，因为组织积累随养分和混合物的变化而变化。