Converting beach-cast seagrass wrack into biochar: A climate-friendly solution to a coastal problem

Peter I Macreadie; Stacey M Trevathan-Tackett; Jeffrey A Baldock; Jeffrey J Kelleway

doi:10.1016/j.scitotenv.2016.09.021

Converting beach-cast seagrass wrack into biochar: A climate-friendly solution to a coastal problem

Sci Total Environ. 2017 Jan 1:574:90-94. doi: 10.1016/j.scitotenv.2016.09.021. Epub 2016 Sep 12.

Authors

Peter I Macreadie¹, Stacey M Trevathan-Tackett², Jeffrey A Baldock³, Jeffrey J Kelleway⁴

Affiliations

¹ School of Life and Environmental Sciences, Centre for Integrative Ecology, Deakin University, Victoria 3125, Australia; Climate Change Cluster, University of Technology Sydney, NSW 2007, Australia. Electronic address: p.macreadie@deakin.edu.au.
² School of Life and Environmental Sciences, Centre for Integrative Ecology, Deakin University, Victoria 3125, Australia; Climate Change Cluster, University of Technology Sydney, NSW 2007, Australia.
³ CSIRO Agriculture and Food, PMB2, Glen Osmond, SA 5064, Australia.
⁴ Climate Change Cluster, University of Technology Sydney, NSW 2007, Australia; Department of Environmental Sciences, Macquarie University, Sydney, NSW 2109, Australia.

PMID: 27623530
DOI: 10.1016/j.scitotenv.2016.09.021

Abstract

Excessive accumulation of plant 'wrack' on beaches as a result of coastal development and beach modification (e.g. groin installation) is a global problem. This study investigated the potential for converting beach-cast seagrass wrack into biochar as a 'climate-friendly' disposal option for resource managers. Wrack samples from 11 seagrass species around Australia were initially screened for their biochar potential using pyrolysis techniques, and then two species - Posidonia australis and Zostera muelleri - underwent detailed analyses. Both species had high levels of refractory materials and high conversion efficiency (48-57%) of plant carbon into biochar carbon, which is comparable to high-quality terrestrial biochar products. P. australis wrack gave higher biochar yields than Z. muelleri consistent with its higher initial carbon content. According to ¹³C NMR, wrack predominantly comprised carbohydrates, protein, and lignin. Aryl carbon typical of pyrogenic materials dominated the spectrum of the thermally-altered organic materials. Overall, this study provides the first data on the feasibility of generating biochar from seagrass wrack, showing that biocharring offers a promising climate-friendly alternative to disposal of beach wrack in landfill by avoiding a portion of the greenhouse gas emissions that would otherwise occur if wrack was left to decompose.

Keywords: Adaptive management; Blue carbon; CO(2); Climate change; Coastal; Emissions.