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Lacerda, Luiz Drude de; Freixo, João L.; Coelho, Simone M.

doi:10.1023/a:1009990604727

Cited by 33 publications

(2 citation statements)

References 26 publications

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“…The more drought-tolerant mangrove A. germinans was unaffected, and the absence of killing freezes during this period rapidly expanded A. germinans cover (McKee et al, 2004). S. alterniflora strongly affects metal and nutrient chemistry in pore waters through intense, but seasonal, root metabolism (Lacerda et al, 1997;Marins et al, 1997). On the other hand, increasing storminess, although potentially threatening, has not been faced vis-à-vis mangrove resilience.…”

Section: A Summary Of Observed Responses Of Mangroves To Climate Chan...mentioning

confidence: 99%

Mangrove Trace Metal Biogeochemistry Response to Global Climate Change

Lacerda¹,

Ward²,

Borges³

et al. 2022

Front. For. Glob. Change

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This review discusses observed impacts from different climate change-driven pressures on mangrove's role in modulating trace metal transfer at the land-ocean interface. It contributes to the literature in a global context and shows mangroves as mitigators or providing positive feedback to metal mobilization. Most chalcophile metals2+ accumulate in mangrove soils associated with sulfides while high sedimentation rates avoid their oxidation. Exudation of oxygen by roots fixates Fe, which co-precipitates metals as oxyhydroxides in the rhizosphere. These two biogeochemical processes reduce trace metal availability to plants and their mobility within estuaries. However, climate change-driven pressures alter this geochemical equilibrium. Increasing atmospheric CO2 and temperature, and the intensity and frequency of extreme climatic events, have proved to affect mangrove functioning and cover, but no direct observation on the impact on metal biogeochemistry is presently available, whereas sea level rise and saline intrusion impacts on the fate of metals have already been observed. Sea level rise increases erosion, that dissociates deposited sulfides releasing metals to the water column. Released metals adsorb onto suspended particles and can re-deposit in the estuary or are exported to continental shelf sediments. Saline intrusion may oxidize deeper sediment layers releasing metals to porewaters. Part of the mobilized metals may remain in solution complexed with DOM and have their bioavailability increased, as shown by high bioaccumulation factors and biomagnification and high metal concentrations in the estuarine biota, which results in higher human exposure through fisheries consumption. Since erosion occurs preferentially at the sea border and higher sedimentation at the higher reaches of the estuary, triggering mangroves migration landward, spatial gradients are formed, and shall be taken into consideration when planning mitigation or adaptation strategies. These observations suggest disruption of traditional humans dwelling in mangrove dominated coastlines by increasing contamination of coastal fisheries, often the principal protein source for those groups and an important source of income. Further research into the environmental and socioeconomic impacts of climate change driven alterations to metal biogeochemical processes in mangroves as contaminant levels are expected to increase.

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Section: A Summary Of Observed Responses Of Mangroves To Climate Chan...mentioning

confidence: 99%

Mangrove Trace Metal Biogeochemistry Response to Global Climate Change

Lacerda¹,

Ward²,

Borges³

et al. 2022

Front. For. Glob. Change

View full text Add to dashboard Cite

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“…For negative values of redox potential (Eh < À150 mV), sulphide tends to precipitate with metals, but between À150 and 200 mV metal mobility is considered to be higher. 18 Plants can oxidize the sediments in the root zone due to the movement of oxygen downwards through aerenchyma tissue (de Lacerda et al, 19 Moorhead and Reddy, 20 Weis and Weis). 2 Since J. maritimus has a well-developed aerenchyma, it is plausible to assume that the Eh values determined, between À148.25 and 258 mV, are higher than those obtained by V alega et al 9 for vegetated sediments, seeming that J. maritimus would be especially effective in oxidizing sediments.…”

Section: Physico-chemical Parameters and Hg Concentration Of The Sedi...mentioning

confidence: 99%

Mercury uptake and allocation in Juncus maritimus: implications for phytoremediation and restoration of a mercury contaminated salt marsh

et al. 2012

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Juncus maritimus is the most abundant macrophyte in Laranjo bay, a Portuguese salt marsh heavily polluted by mercury (Hg). With the aim to elucidate the role of this species in the salt marsh Hg cycling and restoration, plants were harvested between March 2006 and January 2008 from four locations differing in Hg contamination. Metal uptake and distribution between plant organs were evaluated, biomass and Hg pools were also determined. Results showed that J. maritimus may influence the sediment pH and Eh, thus increasing the Hg available for uptake. Most (95-98%) of the absorbed Hg was retained belowground, phytostabilizing the metal and reducing the amount of Hg in the sediments. These results suggest that in salt marshes dominated by J. maritimus the approach could be phytostabilization, where these plants can be used to immobilize metals and store them belowground, reducing the pool of bioavailable Hg within contaminated marshes and acting as a sink rather than a source of contamination to the surrounding areas.

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