Carbon stocks and sequestration of stormwater bioretention/biofiltration basins

• Published in: Ecological engineering Vol. 138; pp. 227 - 236
• Main Authors: Kavehei, Emad, Jenkins, G.A., Lemckert, C., Adame, M.F.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-11-2019; Elsevier BV
• Subjects: Basins; Biofilters; Biofiltration; Biofiltration basin; Carbon; Carbon sequestration; Carbon sources; Ecosystem service; Ecosystem services; Green infrastructure; Organic matter; Ponding; Rain garden; Retention basins; Soil; Soil density; Soil profiles; Soil properties; Soils; Stocks; Stormwater; Stormwater control measure; Green infrastructure; Stormwater control measure; Ecosystem service; Carbon sequestration; Biofiltration basin; Rain garden
• ISSN: 0925-8574; 1872-6992
• DOI: 10.1016/j.ecoleng.2019.07.006

Linear accumulation of C in bioretention soil with age (x axis) and within the soil profile (y axis).
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•Bioretention basins store carbon over the whole ponding area.•Top 5 cm of bioretention’s soil accounts for 32% of soil carbon stocks.•Age is the most influencing factor on soil carbon accumulation.•Low carbon density of the soil below 20 cm in depth and not influenced by age.•Bioretention basins can sequester carbon at a rate of 0.31 kg C m−2 yr−1.
Bioretention basins are a prominent type of vegetated stormwater infrastructure that provides various ecosystem services, such as carbon (C) sequestration. Despite the key role of organic matter in the performance of bioretention basins, there is little understanding of their C accumulation properties. Using detailed field studies, we investigated the spatial, temporal and vertical variation of C capture in the soil of 25 subtropical bioretention basins in Australia. A thirteen-year soil chronosequence was used to estimate C sequestration rate. It was observed that the bioretention basins displayed a spatially uniform depositional pattern of C in their ponding area. The mean areal C density of soil in the upper 20 cm was 3.8 ± 0.3 kg C m−2, from which 32% was associated with the top 5 cm of soil. There was a strong influence of age on C density only throughout the first top 20 cm of the soil profile with a C sequestration rate of 0.31 kg C m−2 yr−1. Carbon quickly accumulates in the top 5 cm layer while in the lower depths it accumulated at a more gradual rate. The results show that bioretention systems could be designed for the enhancement of their C sequestration potential, and amendments in their design, such as addition of a carbon source layer, are important for better managing carbon availability in the basins.