Browsing by Author "Meynard, Andres"

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    Effect of Pyrolysis Temperature on Copper Aqueous Removal Capability of Biochar Derived from the Kelp Macrocystis pyrifera
    (MDPI, 2021) Araya, Matias; Rivas, Jorge; Sepulveda, Graciela; Espinoza Gonzalez, Camila; Lira, Sebastian; Meynard, Andres; Blanco, Elodie; Escalona, Nestor; Ginocchio, Rosanna; Garrido Ramirez, Elizabeth; Contreras Porcia, Loretto
    Seaweed biochar is an efficient alternative bioadsorbent for Cu2+ removal due to its low cost and heavy metal removal capacity. Using the slow pyrolysis process, we produced biochars from Macrocystis pyrifera at 300 (BC300), 450 (BC450), and 600 & DEG;C (BC600). The physicochemical and structural properties of the biochar samples improved with increasing pyrolysis temperature from 300 to 450 & DEG;C, whereas no significant differences were observed with further increases in temperature to 600 & DEG;C. The yield ranged between 49% and 62% and had a high ash content (57.5-71.1%). BC450 and BC600 presented the highest surface areas and higher porosities. The FTIR spectra indicated that an increase of temperature decreased the acidic functional groups due to depolymerization and the dehydration processes, increasing the aromatic structures and the presence of calcium carbonate. The fittings of the kinetic models were different for the BCs: for the BC450 and BC600 samples, the Cu2+ adsorption was well-represented by a pseudo-first-order model; for BC300, a better fit was obtained with the pseudo-second-order model. The rate-limiting step of Cu2+ adsorption on BCs was represented by both models, liquid film diffusion and intraparticle diffusion, with surface diffusion being more important in BC300 and BC600, and intraparticle diffusion in BC450, in agreement with the pore size of the biochar samples. The adsorption isotherms of all BCs showed Langmuir behavior, representative of a chemisorption process, which was corroborated by the energy adsorption values determined by the D-R model. The maximum monolayer Cu2+ adsorption capacities were 93.55 and 58.0 mg g(-1) for BC600 and BC450, respectively, whereas BC450 presented the highest affinity. Other mechanisms involved in controlling heavy metal removal from aqueous suspensions using these seaweed biochars remain to be explored. We conclude that BC450 and BC600 from M. pyrifera are the most efficient adsorbents for Cu2+ aqueous removal and are thus an appropriate alternative for bioremediation.
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    Expansion of marine pollution along the coast: Negative effects on kelps and contamination transference to benthic herbivores?
    (2023) Contreras-Porcia, Loretto; Meynard, Andres; Bulboa, Cristian; Vargas, Paulina; Rivas, Jorge; Latorre-Padilla, Nicolas; Navarrete, Sergio A.; Search, Francesca V.; Oyarzo-Miranda, Carolina; Toro-Mellado, Fernanda
    Heavy metals and polycyclic aromatic hydrocarbons (PAHs) are ubiquitous contaminants that frequently cooccur in coastal environments. These contaminants can have negative impacts on the health and stability of marine and coastal ecosystems, affecting both the organisms themselves and the humans who consume them. A coastal industrial park in central Chile, housing a coal thermal power plant and other industrial activities, contributes to such pollution of coastal waters; however, neither the spatial alongshore distribution of heavy metals and PAHs, nor an assessment of their ecological effects on the biota have been systematically documented to date. In this paper, we present evidence regarding the direct negative effect of contamination by heavy metals and PAHs on the early life stages of kelps-being extremely harmful to their population persistence near highly polluted sites-as well as the indirect effects of their transference through the food web to higher trophic levels, leading to negative consequences for the feeding intake, growth, fertility, and larval development of marine herbivores that consume the contaminated seaweed. Likewise, the dispersion of contaminants by ocean currents can exacerbate the effects of pollution, having an adverse influence on marine ecosystem health even at sites far from the pollution source. Therefore, it is necessary to investigate the distribution patterns and extent of pollution along the coast to understand the impact of heavy metals and PAHs pollution on seaweed populations and the food web. It is considered critical for the development of effective environmental policies and regulations to protect these ecosystems and the people who depend on them.
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    Morphological and Molecular Identification of Ulva spp. (Ulvophyceae; Chlorophyta) from Algarrobo Bay, Chile: Understanding the Composition of Green Tides
    (2024) Mutizabal-Aros, Javiera; Ramirez, Maria Eliana; Haye, Pilar A.; Meynard, Andres; Pinilla-Rojas, Benjamin; Nunez, Alejandra; Latorre-Padilla, Nicolas; Search, Francesca V.; Tapia, Fabian J.; Saldias, Gonzalo S.; Navarrete, Sergio A.; Contreras-Porcia, Loretto
    Green algae blooms of the genus Ulva are occurring globally and are primarily attributed to anthropogenic factors. At Los Tubos beach in Algarrobo Bay along the central Chilean coast, there have been blooms of these algae that persist almost year-round over the past 20 years, leading to environmental, economic, and social issues that affect the local government and communities. The objective of this study was to characterize the species that form these green tides based on a combination of ecological, morpho-anatomical, and molecular information. For this purpose, seasonal surveys of beached algal fronds were conducted between 2021 and 2022. Subsequently, the sampled algae were analyzed morphologically and phylogenetically using the molecular markers ITS1 and tufA, allowing for the identification of at least five taxa. Of these five taxa, three (U. stenophylloides, U. uncialis, U. australis) have laminar, foliose, and distromatic morphology, while the other two (U. compressa, U. aragoensis) have tubular, filamentous, and monostromatic fronds. Intertidal surveys showed that U. stenophylloides showed the highest relative coverage throughout the seasons and all intertidal levels, followed by U. uncialis. Therefore, we can establish that the green tides on the coast of Algarrobo in Chile are multispecific, with differences in relative abundance during different seasons and across the intertidal zone, opening opportunities for diverse future studies, ranging from ecology to algal biotechnology.