State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China.
State Key Laboratory of Hydroscience and Hydraulic Engineering, Tsinghua University, Beijing, China.
Chemosphere. 2024 Sep;364:143276. doi: 10.1016/j.chemosphere.2024.143276. Epub 2024 Sep 6.
Bioretention cells have emerged as a prominent strategy for mitigating pollutant loads within urban stormwater runoff. This study delves into the role of plant uptake in the simultaneous removal of nitrogen and phosphorus compounds within these systems. Three bioretention cells-CP, P1, and P2-were constructed using local soil, C33 sand, and gravel. CP served as the unvegetated control, while P1 and P2 were vegetated with vetiver and cattail, respectively. The removal efficiencies of NO₃⁻-N, NH₃⁻-N, NO₂⁻-N, TN, TP, and COD from rainwater were evaluated under saturated and unsaturated conditions. The unvegetated control reactor (CP) achieved TN and TP removal rates of 40.44% and 82.52%, respectively. Reactor P1 (vetiver) demonstrated TN and TP removal rates of 62.92% and 97.19%, respectively. Reactor P2 (cattail) showed TN and TP removal rates of 49.71% and 87.78%, respectively. With the introduction of a saturation zone, TN removal efficiencies increased to 51.69%, 89.22%, and 79.91% for CP, P1, and P2, respectively. However, TP removal efficiencies decreased to 74.81%, 95.04%, and 84.58% for CP, P1, and P2, respectively. Plant tissue uptake tests indicated that vetiver could retain 5 times more TN and twice as much TP compared to cattail. This enhanced performance is attributed to vetiver's high photosynthetic potential as a C4 plant, resilience to varying environmental and nutrient conditions, extensive root network, secretion of oil sesquiterpenes from its root cortex, and the presence of arbuscular mycorrhizal fungi, which secrete glomalin, a substance that promotes water retention and nutrient uptake. Findings from this study indicate that the efficacy of traditional bioretention cells can be augmented through the strategic selection and integration of locally adapted plant species, coupled with the incorporation of saturation zones, to enhance pollutant removal capabilities and resilience to drought conditions.
生物滞留池已成为减轻城市雨水径流中污染物负荷的重要策略。本研究深入探讨了植物吸收在这些系统中同时去除氮和磷化合物中的作用。使用当地土壤、C33 砂和砾石构建了三个生物滞留池-CP、P1 和 P2。CP 作为无植被对照，而 P1 和 P2 分别用香根草和香蒲植被。在饱和和不饱和条件下，评估了雨水对 NO₃⁻-N、NH₃⁻-N、NO₂⁻-N、TN、TP 和 COD 的去除效率。无植被对照反应器（CP）实现了 TN 和 TP 的去除率分别为 40.44%和 82.52%。反应器 P1（香根草）的 TN 和 TP 去除率分别为 62.92%和 97.19%。反应器 P2（香蒲）的 TN 和 TP 去除率分别为 49.71%和 87.78%。引入饱和区后，CP、P1 和 P2 的 TN 去除效率分别提高到 51.69%、89.22%和 79.91%。然而，TP 的去除效率分别降低到 74.81%、95.04%和 84.58%。植物组织吸收试验表明，香根草比香蒲能保留 5 倍的 TN 和 2 倍的 TP。这种增强的性能归因于香根草作为 C4 植物的高光合潜力、对不同环境和养分条件的恢复能力、广泛的根系网络、从根皮层分泌油倍半萜、以及存在丛枝菌根真菌，其分泌球囊霉素，一种促进水保持和养分吸收的物质。本研究的结果表明，通过有策略地选择和整合适应本地的植物物种，并结合饱和度区的引入，可以提高传统生物滞留池的功效，增强其去除污染物的能力和对干旱条件的恢复能力。
