| Green roofs are a useful tool to retain heat, limit the heat island effect and improve the sustainability of cities, but their effectiveness of nutrient retention is still up for debate. Their ability to retain nutrients is highly dependent on growing media, plant type, climate, and rainfall amount and intensity. This study aims to understand both planted and unplanted aqualok, planted and unplanted lava rock, and aqualok bioswales ability to retain nutrients, total suspended solids and total organic carbon at various location in the District of Columbia. Overall, the planted aqualok and lava rock roofs were able to retain ammonium by 75% and 10% and nitrites/nitrates by 67% and 56%, but other roofs released more nutrients than present in rainfall. The unplanted aqualok and model roof released the most total phosphorous, while the planted aqualok released the most total organic carbon and total suspended solids, along with bioswales. |
