35 documents found, page 1 of 4
Trace elements in soils of the Antarctic ice-free areas: Insights on natural ge...
Zilhão, Henrique; Cesário, Rute; Vieira, Gonçalo; Canário, JoãoClimate change is transforming the ice-free areas of Antarctica, leading to rapid changes in terrestrial ecosystems. These areas represent <0.5% of the continent and coincide with the most anthropogenically pressured sites, where the human footprint is a source of contamination. Simultaneously, these are the locations where permafrost can be found, not being clear what might be the consequences following its de...
Natural organic matter dynamics in permafrost peatlands: critical overview of r...
Folhas, Diogo; Couture, Raoul-Marie; Laurion, Isabelle; Vieira, Gonçalo; Canário, JoãoRising temperatures are destabilizing permafrost in northern latitudes, leading to the mobilization, transformation and cycling of natural organic matter (NOM), nutrients, and contaminants into newly formed aquatic systems. Analyzing the chemical composition of organic matter is crucial for understanding the biogeochemical processes at play. Furthermore, it is essential to investigate how seasonal variations an...
Recent advances in the study of mercury biogeochemistry in Arctic permafrost ec...
Malcata Martins, Beatriz; Hintelmann, Holger; Pilote, Martin; Vieira, Gonçalo; Canário, JoãoPermafrost predominates in polar and high mountain regions, encompassing nearly 15 % of the exposed land in the Northern Hemisphere. It denotes soil or rock that remains at or below 0 °C for the duration of at least two consecutive years. These frozen soils serve as a barrier to contaminants that are stored and accumulated in permafrost over extended periods of time. One of these chemical compounds is mercury (...
Diversity of lakes and ponds in the forest-tundra ecozone: from limnicity to li...
Freitas, Pedro; Vieira, Gonçalo; Martins, Diana; Canário, João; Pina, Pedro; Heim, Birgit; Juhls, Bennet; Couture, Raoul-Marie; Vincent, Warwick F.Arctic and subarctic landscapes have unique hydrological and limnological features and are now experiencing rapid change due to climate warming and permafrost thaw. The highly abundant lakes, ponds, and rivers across these landscapes play an increasingly important role in global biogeochemical cycles and are sentinels of environmental changes. However, studying these remote waters poses challenges for both in s...
A trained Mask R-CNN model over PlanetScope imagery for very-high resolution su...
Freitas, Pedro; Vieira, Gonçalo; Canário, João; Vincent, Warwick F.; Pina, Pedro; Mora, CarlaSmall water bodies (< 0.01 km2) showing diverse limnological properties occur in great abundance across the boreal forest and tundra landscapes of the Arctic and Subarctic. However, their classification, geographical distribution and collective importance for water, heat, nutrient, contaminant and carbon cycles are still poorly constrained. One important step for better understanding the role and evolution of s...
Changes in vessel traffic disrupt tidal flats and saltmarshes in the Tagus Estu...
Martins, Diana; Alves da Silva, Andreia; Duarte, João; Canário, João; Vieira, GonçaloThe Tagus Estuary is one of the largest in Europe with 320 km2 , and it has been, for centuries, a gateway to Lisbon. This study focuses on the Moita-Montijo Bay and on the recent dynamics of its tidal flats and saltmarshes. Aerial photographs, orthomosaics, and very high-resolution satellite imagery were used to analyze landcover and shoreline changes. Tidal flats have shown expansion from 1977 to 1995, but si...
Contamination analysis of Arctic ice samples as planetary field analogs and imp...
Coelho, Lígia F.; Blais, Marie-Amélie; Matveev, Alex; Keller-Costa, Tina; Vincent, Warwick F.; Da Silva Costa, Rodrigo; Martins, Zita; Canário, JoãoMissions to detect extraterrestrial life are being designed to visit Europa and Enceladus in the next decades. The contact between the mission payload and the habitable subsurface of these satellites involves significant risk of forward contamination. The standardization of protocols to decontaminate ice cores from planetary field analogs of icy moons, and monitor the contamination in downstream analysis, has a...
Structural shifts in sea ice prokaryotic communities across a salinity gradient...
Coelho, Lígia Fonseca; Couceiro, Joana Fernandes; Keller-Costa, Tina; Valente, Sara Martinez; Ramalho, Tiago Pereirinha; Carneiro, Joana; Comte, JérômeCurrent knowledge of the processes that shape prokaryotic community assembly in sea ice across polar ecosystems is scarce. Here, we coupled culture-dependent (bacterial isolation on R2A medium) and culture-independent (high throughput 16S rRNA gene sequencing) approaches to provide the first comprehensive assessment of prokaryotic communities in the late winter ice and its underlying water along a natural salin...
Vegetation shadow casts impact remotely sensed reflectance from permafrost thaw...
Freitas, Pedro; Vieira, Gonçalo; Mora, Carla; Canário, João; Vincent, Warwick F.Thermokarst lakes and ponds are a common landscape feature resulting from permafrost thaw, but their intense greenhouse gas emissions are still poorly constrained as a feedback mechanism for global warming because of their diversity, abundance, and remoteness. Thermokarst waterbodies may be small and optically diverse, posing specifc challenges for optical remote sensing regarding detection, classifcation, and ...
Structural characterization of dissolved organic matter in permafrost peatland ...
Folhas, Diogo; Duarte, Armando C.; Pilote, Martin; Vincent, Warwick F.; Freitas, Pedro; Vieira, Gonçalo; Silva, Artur M. S.; Duarte, Regina M. B. O.Thermokarst lakes result from the thawing of ice-rich permafrost and are widespread across northern landscapes. These waters are strong emitters of methane, especially in permafrost peatland regions, where they are stained black by high concentrations of dissolved organic matter (DOM). In the present study, we aimed to structurally characterize the DOM from a set of peatland thermokarst lakes that are known to ...