Iker Marcaida

Study of particulate matter from Primary/Secondary Marine Aerosol and anthropogenic sources collected by a self-made passive sampler for the evaluation of the dry deposition impact on built heritage

Dry deposition is one of the most dangerous processes that can take place in the environment where the compounds that are suspended in the atmosphere can react directly on different surrounding materials, promoting decay processes. Usually this process is related with industrial/urban fog and/or marine aerosol in the coastal areas. Particularly, marine aerosol transports different types of salts which can be deposited on building materials and by dry deposition promotes different decay pathways. A new analytical methodology based on the combined use of Raman Spectroscopy and SEM-EDS (point-by-point and imaging) was applied. For that purpose, firstly evaporated seawater (presence of Primary Marine Aerosol (PMA)) was analyzed. After that, using a self-made passive sampler (SMPS), different suspended particles coming from marine aerosol (transformed particles in the atmosphere (Secondary Marine Aerosol (SMA)) and metallic airborne particulate matter coming from anthropogenic sources, were analyzed. Finally in order to observe if SMA and metallic particles identified in the SMPS can be deposited on a building, sandstone samples from La Galea Fortress (Getxo, north of Spain) located in front of the sea and in the place where the passive sampler was mounted were analyzed.

The influence of rainwater composition on the conservation state of cementitious building materials

Rainwater is one of the main pollution tracers around the world. There are many reasons that can explain the presence of high concentrations of certain hazardous elements (HEs) in the rainwater (traffic, marine port activities, industry, etc.). In this work, rainwater samples were collected at six different locations in the Metropolitan Bilbao (Basque Country, north of Spain) during November 2014. HE concentrations were determined by means of inductively coupled plasma mass spectrometry (ICP-MS) and anions by ion chromatography. The pH and redox potential values on these samples were also assessed. According to the obtained results, different trends along the estuary of Bilbao have been observed. To corroborate some hypothesis, thermodynamic simulations and correlation analyses were also carried out using quantitative data. These trends are closely related to the surrounding pollution and marine influence. Finally, in order to ascertain the influence of the Metropolitan Bilbao rainwater on buildings materials, a recent construction was characterized. Using techniques such as Scanning Electron Microscopy coupled with Energy Dispersive X-Ray Spectroscopy (SEM–EDS) and Raman Spectroscopy, different types of sulfates and nitrates were observed.

In situ X-ray fluorescence-based method to differentiate among red ochre pigments and yellow ochre pigments thermally transformed to red pigments of wall paintings from Pompeii

Most of the magnificent wall paintings from the ancient city of Pompeii are decorated with red and yellow colors coming from the ochre pigments used. The thermal impact of the pyroclastic flow from the eruption of Vesuvius, in AD 79, promoted the transformation of some yellow painted areas to red. In this work, original red ochre, original yellow ochre, and transformed yellow ochre (nowadays showing a red color) of wall paintings from Pompeian houses (House of Marcus Lucretius and House of Gilded Cupids) were analyzed by means of a handheld energy-dispersive X-ray fluorescence spectrometer to develop a fast method that allows chemical differentiation of the original red ochre and the transformed yellow ochre. Principal component analysis of the multivariate obtained data showed that arsenic is the tracer element to distinguish between both red colored ochres. Moreover, Pompeian raw red and yellow ochre pigments recovered from the burial were analyzed in the laboratory with use of a benchtop energy-dispersive X-ray fluorescence spectrometer to confirm the elemental composition and the conclusions drawn from the in situ analysis according to the yellow ochre pigment transformation in real Pompeian wall paintings.

Biodeterioration of Pompeian mural paintings: fungal colonization favoured by the presence of volcanic material residues

This work was focused on the study of the biodegradation processes jeopardizing a mural painting conserved in the basement of Ariadne House (archaeological site of Pompeii, Italy). The fresco stood out for its peculiar state of preservation: the upper part, recovered in 1988, was just barely colonized by microorganisms. On the contrary, the lower part (excavated in 2005) was almost completely covered by extensive biological patinas. The genomic characterization carried out by polymerase chain reaction (PCR) highlighted the presence of seven different fungi strains on the mural surface. Beside, in situ and laboratory analyses were performed with the purpose of identifying the causes of the heterogeneous spatial distribution of the biopatinas. The in situ Raman spectroscopy and energy dispersive X-ray fluorescence (ED-XRF) spectroscopy measurements excluded any link between the heterogeneous colonization and the original materials present in the wall. On the other side, X-ray diffraction (XRD) and scanning electron microscopy (SEM) on microsamples proved the presence of a thin volcanic material layer overlying the lower part of the fresco. Considering that most of the biofilms of the studied mural painting only growth over these residues, it was confirmed the role of volcanic material as a suitable support for biological colonization. Thanks to the obtained results, this research helped to understand more in depth an important degradation pathway threatening the artworks from one of the most important archaeological sites in the world.

Multispectroscopic and Isotopic Ratio Analysis To Characterize the Inorganic Binder Used on Pompeian Pink and Purple Lake Pigments

Because of the fact that pigments are not ubiquitous in the archeological record, the application of noninvasive analytical methods is a necessity. In this work, pink and purple lake pigments recovered from the excavations of the ancient city of Pompeii (Campania, Italy) and preserved in their original bowls at the Naples National Archaeological Museum (Italy) were analyzed to characterize the composition of their inorganic binders (mordants). In situ preliminary analyses using a hand-held energy dispersive X-ray fluorescence spectrometer (HH-ED-XRF) allowed us to determine the use of an aluminosilicate enriched in Cu and Pb. Scanning electron microscopy coupled to energy dispersive X-ray spectrometry (SEM-EDS) and benchtop ED-XRF analyses confirmed these results, while inductively coupled plasma mass spectrometry (ICPMS) allowed one to determine the concentration of major, minor, and trace elements. The use of other techniques such as X-ray diffraction (XRD), and micro-Raman and infrared spectroscopies allowed one to characterize the pigments at the molecular level. The high concentration of Cu detected in the pigments (1228-12937 μg g(-1)) could be related to the addition of Cu salts to obtain the desired final hue. The concentrations of Pb (987-2083 μg g(-1)) was also remarkable. Lead isotopic ratio analysis ((206)Pb/(207)Pb) suggested a possible origin related to the leaching of the ancient lead pipes from Pompeii and the subsequent transfer to the buried pigments or to the inorganic binder. Molecular analysis also showed that the binder is composed of an allophane-like clay. Moreover, it was possible to determine that to obtain the final purple hue of a specific pigment, Pompeian blue pigment was also mixed into the dyed clay.

Study of the soluble salts formation in a recently restored house of Pompeii by in-situ Raman spectroscopy

The walls and mural paintings of Pompeii exposed directly to the rainfalls are the most impacted in view of the observed decay. However, there are also wall paintings in protected rooms showing evidences of decaying. The aim of this research was to study the salts formed in such protected wall paintings only by non-invasive and in-situ Raman spectroscopy to understand their decaying processes. The perystile of the House of the Gilded Cupids (Regio VI, Insula 16), one of the most important houses of Pompeii was studied. Although an exhaustive restoration was carried out in 2004, a new conservation treatment was needed in 2013 and only two years later, extensive crystallizations of soluble salts were again threatening several of the restored surfaces, thus, the presence of an unsolved degradation pathway was deduced. Thank to the proposed methodology, it was pointed out that the key is the acidified rainfall impact in the non-protected backside of the walls containing the wall paintings. Thus, a new concept in the preservation of the houses of Pompeii is provided, in which the need of the protection of those walls from both sides is suggested to avoid the movement of water through the pores of the walls.

Micro-Raman and SEM-EDS analyses to evaluate the nature of salt clusters present in secondary marine aerosol

Marine aerosol is a complex inorganic and organic chemistry system which contains several salts, mainly forming different type of salt clusters. Different meteorological parameters have a key role in the formation of these aggregates. The relative humidity (%RH), temperature, CO, SO2 and NOx levels and even the O3 levels can promote different chemical reactions giving rise to salt clusters with different morphology and sizes. Sulfates, nitrates and chlorides and even mixed chlorosulfates or nitrosulfates are the final compounds which can be found in environments with a direct influence of marine aerosol. In order to collect and analyze these types of compounds, the use of adequate samplers is crucial. In this work, salt clusters were collected thanks to the use of a self-made passive sampler (SMPS) installed in a 20th century historic building (Punta Begoña Galleries, Getxo, Basque Country, Spain) which is surrounded by a beach and a sportive port. These salt clusters were finally analyzed directly by micro-Raman spectroscopy and Scanning Electron microscopy coupled to Energy Dispersive X-ray spectrometry (SEM-EDS).

Optimization of sample treatment for the identification of anthraquinone dyes by surface-enhanced Raman spectroscopy

AbstractThe study and characterization of old artifacts such as pigments requires the use of techniques that need a small amount of sample to perform the analysis because of the high value of these samples. In recent years, organic molecules such as anthraquinone dyes have been identified by surface-enhanced Raman spectroscopy (SERS). However, different sample treatments must be applied to isolate the organic dye from the mordant, which produces great fluorescence in the Raman measurements. In this work, optimization of sample treatment for the SERS analysis of anthraquinone dyes was performed. Sample mass, the organic solvent, and its volume were optimized and different slide materials and excitation lasers were compared to choose the best conditions for the identification of the dyes. The optimization of sample treatment resulted in 5 mg of sample as the optimum amount. Further, two consecutive extractions with 0.5 mL of ethyl acetate was the best option for the extraction of the dye. A quartz slide was used instead of a glass slide to reduce background signal, and an excitation laser of 532 nm offers better results than one of 785 nm. The optimized method was applied to the characterization of the dyes used in Pompeian pink and purple lake pigments. Alizarin and purpurin anthraquinone dyes, obtained from madder lake, were identified as the organic colorants. The SERS results were confirmed by those obtained by means of UV–visible spectroscopy. Graphical Abstractᅟ

Trentepohlia algae biofilms as bioindicator of atmospheric metal pollution

In this work, a reddish biocolonization composed mainly by Trentepohlia algae affecting a synthetic building material from a modern building from the 90s located in the Bizkaia Science and Technology Park (Zamudio, North of Spain) was characterized and its ability to accumulate metals coming from the surrounding atmosphere was evaluated. To asses if these biofilms can act as bioindicators of the surrounding metal pollution, a fast non-invasive in situ methodology based on the use of hand-held energy dispersive X-ray fluorescence (HH-ED-XRF) was used. In order to corroborate the in situ obtained conclusions, some fragments from the affected material were taken to analyze the metal distribution by means of micro-energy dispersive X-ray fluorescence spectroscopy (μ-ED-XRF) and to confirm the presence of metal particles deposited on it using Scanning Electron Microscopy coupled to an Energy Dispersive Spectrometer (SEM-EDS). In order to confirm if Trentepohlia algae biofilms growing on the surface of building materials could be a fast way to in situ provide information about the surrounding metal pollution, a second Trentepohlia algae biofilm growing on a different kind of material (sandstone) was analyzed from an older historical building, La Galea Fortress (Getxo, North of Spain).

In-situ multianalytical approach to analyze and compare the degradation pathways jeopardizing two murals exposed to different environments (Ariadne House, Pompeii, Italy)

This study aimed at using portable analytical techniques to characterize original and decayed materials from two murals paintings of Ariadne House (archaeological site of Pompeii, Italy) and define the degradation pathways threatening their conservation. The first wall, located in an outdoor environment, has been directly exposed to degradation processes triggered by weathering and atmospheric pollution. The second wall, placed in a basement under the ground floor, has been constantly sheltered from sunlight exposure and drastic temperature fluctuations. The analytical data obtained in-situ by using Raman spectroscopy and Laser Induced Breakdown Spectroscopy (LIBS) correlates the degradation patterns affecting the two surfaces to their environmental context. The deterioration processes detected on the outdoor wall, which entailed the complete loss of the paint layer, were mostly related to leaching and thermal fluctuation phenomena. The mural painting from the basement instead, showed deep degradation issues due to soluble salt infiltration and biological colonization. The results obtained from this unique case of study highlight the indispensable role of in-situ spectroscopic analysis to understand and predict the degradation pathways jeopardizing the cultural heritage and provide to the Archaeological Park of Pompeii important inference to consider in future conservation projects.