Author Identifier (ORCID)
Abstract
Blue carbon ecosystems (BCEs) store a significant amount of organic carbon (OC) in their soils, including OC sequestered by other ecosystems and transported into these ecosystems, referred to as allochthonous OC. This study reviews the state-of-the-art knowledge on the abundance and sources (including still unexplored ones) of allochthonous particulate organic carbon (POC) and reviews the ways allochthonous POC is managed under the current blue carbon policy frameworks for carbon benefits accounting in blue carbon restoration and conservation projects. Based on a review of 102 studies, we find that 56 ± 25% of the soil organic carbon (SOC) deposits in BCEs are allochthonous POC, most commonly identified as originating from terrestrial ecosystems, seston and macroalgae. Whether allochthonous POC should be included in blue carbon accounting is a matter of debate among the scientific community, due to the risks of overestimating carbon benefits and double-counting. Consequently, it is often excluded from voluntary carbon markets, but its inclusion can be justified given the role of BCEs in stabilising OC that may otherwise be remineralised. Based on existing knowledge, a deeper understanding of the stability and behaviour of different types of allochthonous POC under varying environmental conditions is needed to assess whether and to what extent these fractions can be counted toward carbon benefits.
Keywords
allochthonous carbon, blue carbon ecosystems, carbon policy, double counting, particulate organic carbon, soil organic carbon
Document Type
Journal Article
Date of Publication
9-1-2026
Article Number
130658
E-ISSN
10958630
ISSN
03014797
Volume
416
PubMed ID
42628391
Publication Title
Journal of Environmental Management
Publisher
Elsevier
School
Centre for Marine Ecosystems Research / School of Science
Funding Information
We thank an Australian Research Council Discovery Grant (DP200100575) for providing funding support for this study. I.M. was supported by a Juan de la Cierva Incorporación postdoctoral fellowship of the Spanish Ministry of Science, Innovation and Universities (JC2020-045917-I). P.I.M. thanks the support of an Australian Research Council grant, Future Fellowship (FT250100371). S.M.T-T. was supported by an ARC DECRA Fellowship (DE210101029). HK acknowledges support provided by the HORIZON-CL5-2023-D1-02-02 grant C-BLUES, Innovation to advance the evidence base for reporting of blue carbon inventories and greenhouse gas fluxes in coastal wetlands.
Funding received from the Australian Research Council (ARC)
DP200100575, FT250100371, DE210101029
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
Recommended Citation
Akhand, A., Mazarrasa, I., Trevathan-Tackett, S. M., Mostofa, K., Chanda, A., Liu, H., Sakugawa, H., Li, S., Liu, C., Lovelock, C. E., Lavery, P., Kennedy, H., & Macreadie, P. I. (2026). Allochthonous particulate organic carbon in blue carbon ecosystems: Implications for accounting, stability, and policy. Journal of Environmental Management, 416, 130658. https://doi.org/10.1016/j.jenvman.2026.130658