Institute of Forestry and Conservation, John H Daniels Faculty of Architecture Landscape and Design, University of Toronto, 33 Willcocks St., Toronto, ON M5S 3B3, Canada.
Department of Civil and Mineral Engineering, University of Toronto, 35 St. George St., Toronto, ON M5S 1A4, Canada.
Sci Total Environ. 2024 Apr 20;922:171302. doi: 10.1016/j.scitotenv.2024.171302. Epub 2024 Feb 28.
Green roofs have been increasingly used to improve stormwater management, but poor vegetation performance on roof systems, varying with vegetation type, can degrade discharge quality. Biochar has been suggested as an effective substrate additive for green roofs to improve plant performance and discharge quality. However, research on the effects of biochar and vegetation on discharge quality in the long term is lacking and the underlying mechanisms involved are unclear. We examined the effects of biochar amendment and vegetation on discharge quality on organic-substrate green roofs with pre-grown sedum mats and direct-seeded native plants for three years and investigated the key factors influencing discharge quality. Sedum mats reduced the leaching of nutrients and particulate matter by 6-64% relative to native plants, largely due to the higher initial vegetation cover of the former. Biochar addition to sedum mat green roofs resulted in the best integrated water quality due to enhanced plant cover and sorption effects. Structural equation modeling revealed that nutrient leaching was primarily influenced by rainfall depth, time, vegetation cover, and substrate pH. Although biochar-amended sedum mats showed better discharge quality from organic-substrate green roofs, additional ecosystem services may be provided by native plants, suggesting future research to optimize plant composition and cover and biochar properties for sustainable green roofs.
绿色屋顶越来越多地被用于改善雨水管理，但屋顶系统中植被表现不佳，因植被类型而异，可能会降低排放水质。生物炭已被提议作为绿色屋顶的有效基质添加剂，以改善植物性能和排放水质。然而，关于生物炭和植被对长期排放水质的影响的研究还很缺乏，其中涉及的潜在机制也不清楚。我们在具有预生长景天垫和直接播种本地植物的有机基质绿色屋顶上进行了为期三年的生物炭改良和植被对排放质量影响的研究，并调查了影响排放质量的关键因素。与本地植物相比，景天垫减少了 6-64%的养分和颗粒物的淋溶，这主要是由于前者较高的初始植被覆盖率。生物炭添加到景天垫绿色屋顶上，由于植物覆盖度的提高和吸附作用，得到了最佳的综合水质。结构方程模型表明，养分淋溶主要受降雨量、时间、植被覆盖度和基质 pH 值的影响。尽管添加生物炭的景天垫从有机基质绿色屋顶中显示出更好的排放水质，但本地植物可能提供额外的生态系统服务，这表明未来需要研究优化植物组成和覆盖度以及生物炭特性，以实现可持续的绿色屋顶。
