Author Identifier (ORCID)
Abstract
Blue carbon ecosystems (BCEs) function as dual repositories of organic carbon and legacy contaminants. While BCEs are recognized carbon sinks, their role as mercury (Hg) sinks and the risk of their conversion into sources due to human and climatic disturbances remain unexplored. This review synthesizes current knowledge on the drivers and risks of contaminant remobilization from threatened BCEs, with a primary focus on mercury. We explore how natural and human disturbances influence Hg storage, release, and bioavailability, while evaluating the risks posed to ecosystems and human health. Through a three-level meta-analysis, we show that physical disturbance remobilizes approximately 54% (95% CI: 8% to 77%) of sediment-bound metals from coastal sediments. Applying this fraction to published BCE Hg stock and loss-rate data, we derived a first-order estimate of 26 (95% CI: 3.9 to 40.8) Mg of total mercury (THg) released annually from BCE degradation and loss worldwide, a flux that offsets approximately 60% of annual BCE Hg burial capacity. The proportion of this bulk THg flux subsequently converted to bioavailable methylmercury (MeHg) depends on local redox conditions and microbial activity, and remains an important uncertainty. We organized the biogeochemical cascade linking sediment disturbance to ecological exposure into two temporally overlapping phases, an immediate physical and chemical release and a delayed biogeochemical exchange, and identified compound disturbance amplification as a critical but previously unrecognized mechanism by which sequential stressors produce non-additive Hg release. Additionally, we identified global BCE-derived Hg risk hotspots through a five-dimensional, evidence-weighted framework applied to 17 UN M49 sub-regions, classifying East Asia, Latin America and the Caribbean, Sub-Saharan Africa, and three Pacific Island sub-regions as Tier 1 high-risk priorities where multiple risk dimensions converge. These findings reframe BCE conservation as simultaneously a carbon, contaminant, and food-security imperative, underscoring the need for legacy-Hg governance alongside atmospheric emission controls under the Minamata Convention.
Keywords
anthropogenic disturbances, climate extremes, coastal ecosystems, contaminant, ecological risks, pollution, remobilization
Document Type
Journal Article
Date of Publication
10-1-2026
Article Number
105622
ISSN
00128252
Volume
281
Publication Title
Earth-Science Reviews
Publisher
Elsevier
School
Centre for Marine Ecosystems Research / School of Science
Funding Information
This work was financially supported by the National Natural Science Foundation of China (U25A20797) and the Guangdong Basic and Applied Basic Research Foundation (2025A151501199).
Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.
Recommended Citation
Zhang, F., Hu, J., Ruiz-Fernández, A. C., Sanders, C. J., Li, X., Chen, R., Bao, K., Neupane, B., Baloch, A., Zheng, Y., & Serrano, O. (2026). Risks of mercury release from disturbance of blue carbon ecosystems. Earth-Science Reviews, 281, Article 105622. https://doi.org/10.1016/j.earscirev.2026.105622