Abstract:
Bioretention facilities are one of the most widely used green stormwater infrastructures. Literature reviews have mainly focused on the control of stormwater runoff quantity and quality, while there is still a gap of systematic research on the emission characteristics of greenhouse gases (GHGs) such as carbon dioxide (CO
2), methane (CH
4) and nitrous oxide (N
2O). To address the above issues, we conducted laboratory column simulation experiments to artificially simulate the quantity and quality of stormwater runoff from urban roads. Compared with the conventional green spaces, we investigated the GHG emission characteristics and carbon reduction effects of three different bioretention structures, namely, traditional bioretention, inverted bioretention, and plant-free bioretention. The experiment results showed that there were significant differences in GHG emission characteristics among different types of bioretention facilities. Among them, the average emission fluxes of CO
2 and N
2O from the inverted bioretention facility were 66.18 mg/(m
2·h) and 2.98 μg/(m
2·h), respectively, which were significantly lower than those of traditional bioretention and plant-free bioretention facilities. The inverted bioretention facility exhibited the lowest total cumulative emission of GHGs, with a global warming potential of 224.18 kg/hm
2, demonstrating a significant carbon reduction advantage over other types of facilities. Specifically, the inverted bioretention facility could reduce CO
2 emissions by 0.40 kg in a single rainfall event, demonstrating its great potential in mitigating GHG emissions. Therefore, the inverted bioretention facility could be preferentially selected for practical engineering applications to effectively reduce GHG emission fluxes. The research findings can support the optimized design of bioretention facilities under the "dual carbon" context.