Evaluating factors affecting soil organic carbon retention in sustainable stormwater nature - based technologies

Low impact development (LID) are prominent type of vegetated stormwater infrastructure that provides various ecosystem services, such as biodiversity, carbon storage, and improvement in air quality. This study investigated six LID technologies to assess SOC retention and factors influencing accumulation. Soil samples (0-20 cm depth) were analyzed using the Walkley-Black method, specifically focusing on wet oxidation. SOC stocks ranged from 18.5 to 66.3 t C/ha in the inflow and 18.6 to 79.1 t C/ha in the outflow, with SCW and TBF showing higher SOC due to root turnover, stormwater runoff, and media composition. This study found that vegetation and impervious catchments significantly influenced SOC levels. Trees exhibited higher SOC due to their extensive root systems and longer life cycles. Roads and parking lots had higher SOC from plant debris and hydrocarbons in stormwater runoff. SOC also varied seasonally, peaking in spring due to photosynthesis and decreasing in summer and autumn from increased microbial respiration. A complex relationship between SOC and soil physico-chemeical perameters were also investigated, with moisture content and total nitrogen being critical factors for carbon stocks. Overall, the results from this study are seen as beneficial in optimizing the design guidelines for LID technologies for carbon sequestration and green space expansion in urban areas.