Nguyen Thanh-Nho, Marchand Cyril, Strady Emilie, Truong-Van Vinh, Tran-Thi Nhu-Trang. (2019). Metals geochemistry and ecological risk assessment in a tropical mangrove (Can Gio, Vietnam). Chemosphere, 219, p. 365-382. ISSN 0045-6535.
Titre du document
Metals geochemistry and ecological risk assessment in a tropical mangrove (Can Gio, Vietnam)
Année de publication
2019
Auteurs
Nguyen Thanh-Nho, Marchand Cyril, Strady Emilie, Truong-Van Vinh, Tran-Thi Nhu-Trang
Source
Chemosphere, 2019,
219, p. 365-382 ISSN 0045-6535
Mangrove sediments act as natural biogeochemical reactors, modifying metals partitioning after their deposition. The objectives of the present study were: to determine distribution and partitioning of metals (Fe, Mn, Ni, Cr, Cu, Co and As) in sediments and pore-waters of Can Gio Mangrove; and to assess their ecological risks based on Risk Assessment Code. Three cores were collected within a mudflat, beneath Avicennia a lba and Rhizophora apiculata stands. We suggest that most metals had a natural origin, being deposited in the mangrove mainly as oxyhydroxides derived from the upstream lateritic soils. This hypothesis could be supported by the high proportion of metals in the residual fraction (mean values (%): 71.9, 30.7, 80.7, 80.9, 67.9, 53.4 and 66.5 for Fe, Mn, Ni, Cr, Cu, Co, and As respectively, in the mudflat). The enrichment of mangrove-derived organic matter from the mudflat to the Rhizophora stand (i.e. up to 4.6% of TOC) played a key role in controlling metals partitioning. We suggest that dissolution of Fe and Mn oxyhydroxides in reducing condition during decomposition of organic matter may be a major source of dissolved metals in pore-waters. Only Mn exhibited a potential high risk to the ecosystem. Most metals stocks in the sediments were higher in the Avicennia stand than the Rhizophora stand, possibly because of enhanced dissolution of metal bearing phases beneath later one. In a context of enhanced mangrove forests destruction, this study provides insights on the effects of perturbation and oxidation of sediments on metal release to the environment.
Plan de classement
Sciences du milieu [021]
;
Géologie et formations superficielles [064]
;
Etudes, transformation, conservation du milieu naturel [082]
Localisation
Fonds IRD [F B010078428]
Identifiant IRD
fdi:010078428
