Institute of Molecular Sciences

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Optimized metrological and geochemical assessment of trends in estuarine and oceanic systems

Publication . Borges, Carlos; Silva, Ricardo Jorge Neves Bettencourt da; Palma, Carla Maria Ferreira Mesquita

The evaluation of the environmental status and evolution of an ecosystem is a crucial element to support decision-makers in their management. Such evaluation must incorporate the uncertainty of collected information to allow their objective and binding interpretation. However, up to now, there were no tools for the objective interpretation of environmental monitoring data that consider system heterogeneity and the impact of the sampling strategy in system characterization, making these monitoring inefficient. The main goal of this work was to produce tools, implemented in user-friendly software, for the objective assessment of the status, trends and correlations of relevant parameters of vast environmental areas, to produce biding information for the management of these resources. The Monte Carlo Method simulation of the spatial distribution of studied parameters considering sampling positioning and sample analysis uncertainty, and conservative interpolation of information between sampling points, allowed simulating mean compositional values, trends and correlations with known uncertainty. This tool was applied to study a large estuarine system from the Tagus River and an even larger coastal area from the Portuguese Continental Platform. The developed tool was successfully applied to study nutrients and characteristic oceanographic features in the oceanic area. The tool was developed for areas monitored from up to 100 points using prior information from studied quantities while keeping the studied parameter’s correlation. The application of the developed tools to the above-mentioned systems in different seasonal conditions allowed the objective and metrologically sound evaluation of trends and correlations of studied parameters. This work aims to change the paradigm of probably the most demanding analytical challenge, the monitoring of vast environmental areas, contributing to the objectivity ambitioned for these studies.

2025-01-23Doctoral thesis

Open access

First report on the synergistic interaction between essential oils against the pinewood nematode Bursaphelenchus xylophilus

Publication . Faria, Jorge M. S.; Cavaco, Tomás; Gonçalves, Diogo; Barbosa, Pedro; Teixeira, Dora Martins; Moiteiro, Cristina; Inácio, Maria L.

Control of the pinewood nematode (PWN), the causal agent of pine wilt disease, can be achieved through the trunk injection of nematicides; however, many pesticides have been linked to environmental and human health concerns. Essential oils (EOs) are suitable alternatives due to their biodegradability and low toxicity to mammals. These complex mixtures of plant volatiles often display multiple biological activities and synergistic interactions between their compounds. The present work profiled the toxicity of eight EOs against the PWN in comparison to their 1:1 mixtures, to screen for successful synergistic interactions. Additionally, the main compounds of the most synergistic mixtures were characterized for their predicted environmental fate and toxicity to mammals in comparison to emamectin benzoate, a commercial nematicide used against PWN. The mixtures of Cymbopogon citratus with Mentha piperita and of Foeniculum vulgare with Satureja montana EOs showed the highest activities, with half-maximal effective concentrations (EC50) of 0.09 and 0.05 L/mL, respectively. For these, complete PWN mortality was reached after only ca. 15 min or 2 h of direct contact, respectively. Their major compounds had a higher predicted affinity to air and water environmental compartments and are reported to have very low toxicity to mammals, with low acute oral and dermal toxicities. In comparison, emamectin benzoate showed lower nematicidal activity, a higher affinity to the soil and sediments environmental compartments and higher reported oral and dermal toxicity to mammals. Overall, uncovering synergistic activities in combinations of EOs from plants of different families may prove to be a source of biopesticides with optimized toxicity against PWNs.

2023-06Journal article

Open access