6 research outputs found
Pesticides and polychlorinated biphenyls (PCBs) contamination and ecotoxicity in estuarine biota
Tese de mestrado, Ciências do Mar, 2022, Universidade de Lisboa, Faculdade de CiênciasThis project reports the analysis of organochloride pesticides and polychlorinated biphenyls
(PCBs) compoundsin a marsh environment, to observe its toxicological effects on a marine model
organism.
To achieve this goal, it was quantified the concentration of organocloride pesticides and PCBs
in sediments and plants, with origin in Alcochete, Rosário in Seixal estuaries. In this case, we
chose to study Spartina maritima. To extract the pollutants, it was used the ASE and QuEChERS
techniquesin sediments and plants samples, respectively, and the GC-ECD technique to analyze
its content.
With this experiment, it was possible to conclude that pesticide compounds were more
predominant in Rosário, while PCBs compounds were more predominant in Seixal, derived from
the activities that occurred in the vicinity of those sites. Alcochete was the less polluted site that
was analysed in this work. When comparing the results obtained in this work with other
concentrations from the same compounds in other Portuguese estuaries, it was possible to observe
that the Tagus estuary presented a higher level of these contaminants. This is due to the higher
population and activity that occurs in this zone, in comparison to other Portuguese estuaries.
When studying the compounds’ concentration on plants, it was possible to observe a higher
concentration on the rhizosediments.
To test the toxicity of these compounds we exposed PCB 153 at 1 µg/L, 3 µg/L and 6 µg/L
to the diatom model Phaeodactylum tricornutum. Afterwards, we analysed the biomarkers growth
rate, photochemistry, pigment, fatty acids, lipid peroxidation and antioxidant enzyme activity of
the cell.
It was possible to observe that, when exposed to the compound, the cells suffered from growth
inhibition, oxidative stress, and photosynthesis inhibition, such as the closure of the reaction’s
centres and damage in the photosystem. This occured even though they presented counter
mechanisms to the toxic effects, such as the incrementation of photosynthetic effects, such as the
grouping probability, increase of efficiency of the electron transport from PQH2 to PSI, and
biochemical such as the incrementation of photoprotective pigments and pigments which increase
the ability to trap photons for the reductions that happen in the photosynthesis and increases the
activity of antioxidant enzymes
Carnivores cross irrigation canals more often through overpasses than through culverts
As rainfall becomes scarcer or more erratic, we rely more on irrigation systems for agricultural and human water provision.
Impacts of irrigation canals such as the barrier effect on wildlife movements are poorly documented. Although canal culverts
and overpasses can be used by wildlife, little is known about their crossing behavior to guide barrier effect mitigation efforts.
Over seven years, we recorded medium-sized carnivore crossings by video-surveillance through 30 culverts and 28 overpasses
in a large irrigation project in south-central Portugal. We examined the in fl uence of the structures ’ features and landscape con-
text on the likelihood of canal crossing. Culvert crossings were positively in fl uenced by the proportion of nearby montado, a
high nature value farming system. Overpass crossings were more likely in areas away from paved roads and with more nearby
wetlands. Overpasses increased the crossing rates by about 11% relative to culverts and both were crossed more often in land-
scapes with evenly distributed land uses. In the project area, 20% of the montado has recently transitioned to irrigated agricul-
ture, and wetlands have increased by 43%. It is therefore plausible that the increase in the crossing rate of overpasses relative to
culverts will be accentuated. Our study produced the fi rst evidence of a contrast in crossing rates among irrigation canal cross-
ing structures. We have shown that the landscape can be a driver of animal crossings but irrigation projects can in turn be trans-
formative of the landscape. Broadly, the fact that the deployment of irrigation canals may favor some land uses over others
creates a conundrum that needs careful consideration when planning barrier effect mitigation interventions
Toxicological evaluation of pterospartum tridentatum flower water
Pterospartum tridentatum Willk. (prickled broom) is an autochthonous
plant, common in Portuguese territory.
The yellow flowers are widely used in traditional medicine, as a potential cure for all
body illnesses, mainly for throat irritation treatment or for diabetes, hypertension and
hypercholesterolemia therapy.
Despite its wide traditional use, no toxicological assessment of this plant has been
performed, as far as we know. The major goal of this work was the P. tridentatum water
extracts safety assessment.
Methodology: Chemical characterization of MS analysis of P. tridentatum flower
extract was performed by ESI-MS spectroscopy; phenols and quercetins content were
also determined. Antioxidant activity was evaluated through -carotene bleaching test
and ABTS radical-scavenging activity. Oxygen consumption of isolated mitochondria
was determined polarographically with a Clark oxygen electrode and mitochondrial
respiratory rates evaluated accordingly to Chance and Williams (1956) and
mitochondrial swelling was evaluated the apparent absorbance changes at 520 nm.
Results and discussion: A high antioxidant activity of P. tridentatum flower water
extract was assessed in good agreement with its ESI-MS spectrum that revealed the
presence of several flavonoids, as luteolin-O-(O-acetyl)-glucuronide, luteolin-Oglucuronide
or isorhamnetin-O-hexoside.
Mitocondrial respiratory rates (state 4, state 3 and FCCP-stimulated respiration) and
respiratory indexes (respiratory control and P/O ratios) showed no consistent decrease
of respiratory and phosphorylative efficiencies for the concentrations tested (up to 500
μg.mL-1). In conclusion, for the concentration range commonly used P. tridentatum
flowers usage can be regarded as harmless and trustworthy and due to its great
antioxidant properties it is useful to counteract diabetes mellitus associated diseases
Detection and possible elimination of the first recorded population of the zebra mussel (Dreissena polymorpha) in Portugal from a reservoir
The zebra mussel, Dreissena polymorpha, has strong economic and environmental
effects within a wide range of habitats, including reservoirs, and there is a need to
monitor in advance of an arrival so that an elimination might be possible. We report
the establishment of the zebra mussel in the Alfundão Reservoir, a small reservoir
in south Portugal, 190 km away from the closest known population in Spain. The
area has been monitored using suspended ropes since 2016, and during October
2019, mussels of 5–43.8 mm shell length were recorded for the first time in the
Alfundão reservoir. The shallow lined reservoir was then chlorinated and drained.
To date, this treatment appears to have been successful in eliminating this
population. It is unknown how this mussel arrived, since the reservoir area has a
surrounding exclusion zone
Antioxidant capacity and toxicological evaluation of pterospartum tridentatum flower extracts
Pterospartum tridentatum Willk. (prickled broom) is an autochthonous plant, common
in Portuguese territory.
The yellow flowers are used in traditional medicine, as a potential cure for all body
illnesses, mainly for throat irritation treatment or for diabetes, hypertension and
hypercholesterolemia therapy.Despite its traditional use, no toxicological assessment has been performed as we know.
A high antioxidant activity of P. tridentatum flower water extract was acessed in good
agreement with its ESI-MS spectrum that revealed the presence of several flavonoids, as
luteolin-O-(O-acetyl)-glucuronide, luteolin-O- glucuronide or isorhamnetin-O-hexoside.
Mitocondrial respiratory rates (state 4, state 3 and FCCP-stimulated respiration) and
respiratory indexes (respiratory control and P/O ratios) showed no consistent decrease
of respiratory and phosphorylative efficiencies for the concentrations tested (up to 500
μg.mL-1). Cytotoxicity evaluation, using MTT assay, was reliable with the previous
results. In conclusion, for the concentration range commonly used P. tridentatum
flowers usage can be regarded as harmless and trustworthy