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Research Project
INSTITUTE OF EARTH SCIENCES
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Publications
Analysis of the urban heat island in Bragança, Portugal, using MODIS data (2003-2022)
Publication . Almeida, Cátia Rodrigues de; Alirio, João; Gonçalves, Artur; Teodoro, Ana Cláudia
Urban Heat Island (UHI) is an effect that corroborates to the increase of temperature in urban settlements when
compared to the surrounding vegetated areas, especially after sunset. This research aimed to understand the Surface
Urban Heat Island (SUHI), a sub-classification correlated to the UHI effect, in the city of Bragança (Portugal), at 23
points classified in different Local Climate Zone (LCZ), between 2003 and 2022, using Remote Sensing (RS) data from
the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor. The data were obtained at four passage times:
11am, 1pm, 10pm and 2am and analysed separately for summer and winter. Qualitative and quantitative analyses were
applied, using an average of 1,337 Land Surface Temperature (LST) data, processed in the Google Earth Engine (GEE)
platform. The computation of the SUHI intensity (SUHIint) for each year was obtained from the differences in LST
between each of the LCZ and the average values from Rural Areas (RCD), considering both summer and winter
campaigns. The boxplots showed similar medians in all LCZs at 11am and 1pm. At 10pm and 2am, only slight
differences were found among the median values. The similarity in results may be associated with the low spatial
resolution of the sensor and the difficulty in distinguishing between LCZs. The SUHIint was positive in most of the
results (about 71%). Of the 23 points analysed, ten were not located in unique pixels, which compromised the analysis of
the results in the different LCZs. This condition reinforces the need for use higher spatial resolution data to allow for a
differentiation among LCZs data.
A LCT pegmatite spectral library of the aldeia spodumene deposit: contributes to mineral exploration
Publication . Almeida, Cátia Rodrigues de; Santos, Douglas; Vasques, Julia Tucker; Cardoso-Fernandes, Joana; Lima, Alexandre; Teodoro, Ana Cláudia
Several methodologies can be employed in the prospection of
Lithium (Li) in hard-rock (pegmatites). Spectrometry
analysis, a Remote Sensing (RS) technique, can be applied to
understand the surface spectral response of a sample, both to
identify the rock-forming or alteration minerals in its
composition and to validate the data collected in situ (by
sensors onboard satellites/drones, for example). This paper
aims to make available for public use the information
acquired on the spectral composition of rock samples from
the Barroso pegmatite field in Portugal, within the scope of
the INOVMINERAL4.0 project. As a result, a spectral library
was created with 47 spectra, collected from 11 different
samples. All data is made available in a universal format, thus
contributing to open science, corroborating the validation of
local spectral data, and stimulating the creation of other
databases, in other locations.
Spectral library of European pegmatites, pegmatite minerals and pegmatite host-rocks – the GREENPEG project database
Publication . Cardoso-Fernandes, Joana; Santos, Douglas; Almeida, Cátia Rodrigues de; Lima, Alexandre; Teodoro, Ana Cláudia
The New Exploration Tools for European Pegmatite Green-Tech Resources (GREENPEG) spectral
database contains the spectral signature, obtained through reflectance spectroscopy studies, of European
pegmatites and minerals as well as their host rocks. Samples include pegmatites of the Nb–Y–F (NYF) and
Li–Cs–Ta (LCT) chemical types and host rocks from pegmatite locations in Austria, Ireland, Norway, Portugal,
and Spain. The database contains the reflectance spectra (raw and continuum-removed spectra), sample photographs,
and main absorption features automatically extracted by a self-proposed Python routine. Whenever
possible, spectral mineralogy was interpreted based on the continuum-removed spectra. A detailed description
of the database, its content and structure, the measuring instrument, and interoperability with geographic information
system (GIS) tools is available in this database report. Moreover, examples of how the data can be
used and interpreted are also provided. The advantages and added value of the presented dataset reside in its
European scale, with representative samples from pegmatites with distinct genesis, mineralogy, structure, and
host rocks that can be used as a reference for pegmatite exploration at a global scale via, for example, satellite
image processing. The reported spectral mineral assemblages can also be of interest when considering resource
estimation or ore processing. Thus, it is expected that this open dataset, available on the Zenodo platform
https://doi.org/10.5281/zenodo.6518318 (Cardoso-Fernandes et al., 2022b), will be a reference for distinct types
of users, ranging from academia to industry.
The Development of a Novel Nitrate Portable Measurement System Based on a UV Paired Diode–Photodiode
Publication . Fernandes, Samuel; Tlemçani, Mouhaydine; Bortoli, Daniele; Feliciano, Manuel; Lopes, Maria Elmina
Nitrates can cause severe ecological imbalances in aquatic ecosystems, with considerable consequences for human health. Therefore, monitoring this inorganic form of nitrogen is essential for any water quality management structure. This research was conducted to develop a novel Nitrate Portable Measurement System (NPMS) to monitor nitrate concentrations in water samples. NPMS is a reagent-free ultraviolet system developed using low-cost electronic components. Its operation principle is based on the Beer–Lambert law for measuring nitrate concentrations in water samples through light absorption in the spectral range of 295–315 nm. The system is equipped with a ready-to-use ultraviolet sensor, light emission diode (LED), op-amp, microcontroller, liquid crystal display, quartz cuvette, temperature sensor, and battery. All the components are assembled in a 3D-printed enclosure box, which allows a very compact self-contained equipment with high portability, enabling field and near-real-time measurements. The proposed methodology and the developed instrument were used to analyze multiple nitrate standard solutions. The performance was evaluated in comparison to the Nicolet Evolution 300, a classical UV–Vis spectrophotometer. The results demonstrate a strong correlation between the retrieved measurements by both instruments within the investigated spectral band and for concentrations above 5 mg NO3−/L.
The INOVMineral project’s contribution to mineral exploration - a WebGIS integration and visualization of spectral and geophysical properties of the aldeia lct pegmatite spodumene deposit
Publication . Cardoso-Fernandes, Joana; Santos, Douglas; Almeida, Cátia Rodrigues de; Vasques, Julia Tucker; Mendes, Ariane; Ribeiro, Ricardo; Azzalini, Antonio; Duarte, Lia; Moura, Rui; Lima, Alexandre; Teodoro, Ana Cláudia
Due to the current energetic transition, new geological exploration technologies are needed
to discover mineral deposits containing critical materials such as lithium (Li). The vast majority of
European Li deposits are related to Li–Cs–Ta (LCT) pegmatites. A review of the literature indicates
that conventional exploration campaigns are dominated by geochemical surveys and related exploration
tools. However, other exploration techniques must be evaluated, namely, remote sensing (RS)
and geophysics. This work presents the results of the INOVMINERAL4.0 project obtained through
alternative approaches to traditional geochemistry that were gathered and integrated into a webGIS
application. The specific objectives were to: (i) assess the potential of high-resolution elevation data;
(ii) evaluate geophysical methods, particularly radiometry; (iii) establish a methodology for spectral
data acquisition and build a spectral library; (iv) compare obtained spectra with Landsat 9 data for
pegmatite identification; and (v) implement a user-friendly webGIS platform for data integration and
visualization. Radiometric data acquisition using geophysical techniques effectively discriminated
pegmatites from host rocks. The developed spectral library provides valuable insights for spacebased
exploration. Landsat 9 data accurately identified known LCT pegmatite targets compared with
Landsat 8. The user-friendly webGIS platform facilitates data integration, visualization, and sharing,
supporting potential users in similar exploration approaches.
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Funders
Funding agency
Fundação para a Ciência e a Tecnologia
Funding programme
6817 - DCRRNI ID
Funding Award Number
UIDP/04683/2020