Edafoloxía e Química Agrícola

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Removal of Phenolic Compounds using Compost from Chicken Manure and Cardboard as Bulking Agent: Adsorption Tests and Cost Analysis
(Springer, 2026-03-10) Al-Zawahreh, Khaled; Paradelo Núñez, Remigio; Universidade de Santiago de Compostela. Centro Interdisciplinar de Investigación en Tecnoloxías Ambientais (CRETUS)
Recently, there has been increased interest in the use of composting to develop bioadsorbents for different pollutants. In this work, the removal of phenol, 2-nitrophenol, and 2,4-dinitrophenol from water is examined using compost derived from chicken manure (C/N ratio 6.3) and cardboard (C/N ratio 202.2) as a low-cost bulking agent. Characterization of the compost indicated its maturity, stability, and the presence of diverse surface functional groups. Toxicity Characteristic Leaching Procedure indicated that the bioavailability of toxic heavy metals including Cr, Pb, Cd, Zn, and Cu was negligible and below the regulated limits. Following a univariate experimental design, the effect of a number of operational factors on phenol adsorption by compost was assessed. The optimum operational factors for removing phenolic compounds are compost dosage 6.0 g L−1, pH 2.0, contact time 80.0 min, and temperature 35.0 °C. The adsorption rate was adequately described using the pseudo-second order model, with relatively high estimated adsorption rates, 0.52–0.97 mg g−1 min−1. Adsorption curves of phenols were adequately presented by the Langmuir model with maximum uptake capacity of 111.0 mg g−1 for phenol, 125.0 mg g−1 for 2-nitrophenol, and 134.0 mg g−1 for 2,4-dinitrophenol, comparable to other expensive adsorbents such as activated carbon, metal–organic frameworks or nano-adsorbents. The higher removal capacity of 2-nitrophenol and 2,4-dinitrophenol over phenol is attributed to higher solubility of phenol in water and the involvement of -NO2 group in H-bonding with carboxylic group-rich-surface. The estimated production cost of compost is 0.04 USD per kg and 0.035 US Cent is needed to remove 1.0 g phenol from water.
Trace metal extractability and bioaccessibility in urban soils
(Springer, 2026-02-12) Roo, María; Herbón Allo, Cecilia; Martín Sanz, Juan Pedro; Barral Silva, María Teresa; Paradelo Núñez, Remigio; Universidade de Santiago de Compostela. Centro Interdisciplinar de Investigación en Tecnoloxías Ambientais (CRETUS)
Abstract Purpose One of the most challenging issues in urban soils is the accumulation of pollutants such as heavy metals, which could reach the natural waters or enter the food chain through plant uptake. In order to assess the health risk related it is necessary to know their availability. Methods We analyzed the chemical extractability of five trace metals (Pb, Cu, Zn, Ni and Cr) in 55 soils from Santiago de Compostela (Spain) with diverse land use (urban grassland, urban forest, urban agriculture) and parent material lithology (granite, schist, gneiss, amphibolite). Soluble metals were evaluated using an extraction with 0.01 M CaCl2, plant-available metals were obtained after extraction with EDTA, and bioaccessibility was assessed following the USEPA in vitro extraction with glycine. Results Metal extractability was in general higher in the USEPA method than in EDTA, and much higher than in CaCl2. Among the elements studied, only Zn was detected consistently in CaCl2 extract, with values always lower than 3% of the total contents, in a decreasing sequence Zn > Pb > Ni > Cu > Cr. Concentrations of plant-available metals followed a decreasing sequence Pb > Cu > Zn > Ni > Cr, with values that represented, on average, between 1 and 23% of their total concentrations. Bioaccessibility followed a similar sequence: Pb > Cu > Zn > Ni > Cr, with values that ranged between 2 and 55% of the total concentrations. Plant-available and bioaccessible Cu and Zn were higher in urban garden soils with respect to other uses. Conclusion The availability of trace metals in these soils is very low and supports previous hypotheses about their sources, with Cu, Pb and Zn coming from anthropogenic pollution and Ni and Cr from natural sources related to the soils parent material.
A Two-Part Harmony: Changes in Peat Molecular Composition in Two Cores from an Ombrotrophic Peatland (Tremoal do Pedrido, Xistral Mountains, NW Spain)
(MDPI, 2025-02-12) Martínez Cortizas, Antonio; Francos Golán, Ainé; Traoré, Mohamed; López Costas, Olalla; Universidade de Santiago de Compostela. Departamento de Edafoloxía e Química Agrícola; Universidade de Santiago de Compostela. Centro Interdisciplinar de Investigación en Tecnoloxías Ambientais (CRETUS); Universidade de Santiago de Compostela. Departamento de Historia
In peat research, the question often arises as to how similar/different the records of cores collected in the same mire are. This has been addressed for some metals (e.g., Pb and Hg), but the question remains open for the molecular composition of organic matter (pOM). Here, we explore this issue by analysing two cores from a raised bog, combining FTIR-ATR, mid-infrared (MIR) indices, and principal component analysis (PCA), and support the interpretation with multilinear regression (MLR) modelling of peat physical (colour) and elemental (C, N, and C/N) properties. The MIR indices and principal components showed depth patterns mainly related to long- and short-term peat decomposition, as well as other secondary changes involving some compounds (e.g., lignin). The depth records of the two cores are remarkably similar, indicating they were synchronously affected by the same processes and to almost the same degree. Cellulose crystallinity was the only property that showed differences in intensity. The good-to-excellent fitting of the MLR models supports the usefulness of FTIR-ATR in peat research. Further studies in a larger number of cores, from the same peatland and from different types of peatlands, are needed to better understand the spatio-temporal responses of the pOM and the factors involved.
Heavy Metal Pollution in a Cu Mine Dump and in Close Agricultural Soils and Crops in Mozambique
(MDPI, 2025-03-19) Savaio, Severino dos Santos; Barreiro Buján, Ana; Núñez Delgado, Avelino; Suluda, Antonio; Álvarez Rodríguez, Esperanza; Fernández Sanjurjo, María J.; Universidade de Santiago de Compostela. Departamento de Edafoloxía e Química Agrícola
Heavy metal pollution is investigated for a mine dump and soils and crops located 0.5, 1, 1.5, 3 and 6 km from a Cu mine, analyzing the total, available and exchangeable Cu, Zn, Cr, Ni, Cd and Pb. The maximum total contents in the dumping site reached 10,000, 1500, 1000, 230, 180 and 0.6 mg kg−1 for Cu, Cr, Ni, Zn, Pb and Cd, respectively. Within agricultural soils, those located 1.5 km away showed the highest total concentrations. The available Cu, Zn, Cd and Pb values were higher in the dump compared with the soils, while Cr and Ni stood out in the samples located 1.5 km away. Regarding crops, the Cu, Cr, Ni, Cd and Pb concentrations were higher in plants situated 3 km away. Considering the toxicity limits, Cr and Ni presented higher levels in most cases, while Cu exceeded the limits in most of the dump and soil samples located 1.5 km away, whereas Pb only exceeded them in the dump. The contents in crops indicated higher values in plants growing 3 km away, with all samples showing Cr pollution problems. These results can be considered of environmental significance, both for Mozambique and globally in areas affected by heavy metal pollution caused by mining activities.
Perennial crops shape the soil microbial community and increase the soil carbon in the upper soil layer
(Elsevier, 2024-10-13) Li, Shoujiao; Barreiro Buján, Ana; Almeida, Juan Pablo; Prade, Thomas; Dimitrova Mårtensson, Linda-Maria; Universidade de Santiago de Compostela. Departamento de Edafoloxía e Química Agrícola
Soil biodiversity is threatened by intensive agriculture that relies on annual grain crop production, thus leading to a decline in soil functions and ecosystem services. Perennial grain crops have a positive impact on the soil microbial community, but the responsive microbial groups and the magnitude of their response remain uncertain. To elucidate this, we analysed soil microbial biomass and community composition, bacterial growth and soil total carbon in five crops: organic perennial intermediate wheatgrass (IWG, Thinopyrum intermedium, Kernza®), organic IWG-alfalfa intercrop, organic biennial grass-legume mixture, organic annual wheat or rye and conventional annual wheat. The analysis was carried out at three time points under two growing seasons at four different soil depths. Five years after establishment, IWG had greater amounts of soil total fungi and bacteria, and of arbuscular mycorrhizal (AM) fungi, saprotrophic fungi, gram-negative (G−) and gram-positive (G+) bacteria compared to annual wheat. Crop perenniality influenced the soil microbial community structure although precipitation, soil temperature and water content were the main drivers of the patterns of and temporal variations in the microbial community. Perennial crops, with reduced tillage and low nitrogen input management increased the proportions of fungi relative to bacteria, AM fungi to saprotrophic fungi, G− bacteria to G+ bacteria, and the growth rate of total bacteria. This resulted in a more active soil microbial community with higher microbial biomass than annual wheat and contributed to the increased soil total carbon storage in the 0–5 cm soil layer in a humid continental climate. The findings emphasize the importance of combining a no tillage strategy with long-term vegetation cover to increase soil quality.
Ciprofloxacin and Trimethoprim Adsorption/Desorption in Agricultural Soils
(MDPI, 2022-07-10) Rodríguez López, Lucia; Santás Miguel, Vanesa; Cela Dablanca, Raquel; Núñez Delgado, Avelino; Álvarez Rodríguez, Esperanza; Pérez Rodríguez, Paula; Arias Estévez, Manuel; Universidade de Santiago de Compostela. Departamento de Edafoloxía e Química Agrícola
The current research focuses on the adsorption/desorption characteristics of the antibiotics ciprofloxacin (CIP) and trimethoprim (TRI) taking place in 17 agricultural soils, which are studied by means of batch-type experiments. The results show that adsorption was higher for CIP, with Freundlich KF values ranging between 1150 and 5086 Ln µmol1−n kg−1, while they were between 29 and 110 Ln µmol1−n kg−1 in the case of TRI. Other parameters, such as the Langmuir maximum adsorption capacity (qm(ads)), as well as the Kd parameter in the linear model and also the adsorption percentages, follow the same trend as KF. Desorption was lower for CIP (with KF(des) values in the range 1089–6234 Ln µmol1−n kg−1) than for TRI (with KF(des) ranging between 26 and 138 Ln µmol1−n kg−1). The higher irreversibility of CIP adsorption was also confirmed by its lower nF(des)/nF(ads) ratios, compared to TRI. Regarding soil characteristics, it was evidenced that nitrogen and carbon contents, as well as mineral fractions, had the highest influence on the adsorption/desorption process. These results can be considered relevant as regards the fate of both antibiotics when they reach the environment as pollutants and therefore could be considered in assessment procedures focused on environmental and public health aspects
Agro-waste materials: A low-cost approach to ionophore antibiotics mitigation in aquatic environment
(Elsevier, 2025-11-12) Hamdi, Samiha; Issaoui, Manel; Míguez González, Ainoa; Cela Dablanca, Raquel; Hammami, Sonia; Barreiro Buján, Ana; Fernández Sanjurjo, María J.; Núñez Delgado, Avelino; Álvarez Rodríguez, Esperanza; Universidade de Santiago de Compostela. Departamento de Edafoloxía e Química Agrícola
Ionophore antibiotics, such as lasalocid (LAS), have emerged as significant environmental contaminants due to their extensive use, high toxicity, and persistence. This study evaluated the adsorption-desorption behavior of LAS on fourteen low-cost by-products using batch experiments. To elucidate the adsorption mechanisms, Fourier Transform Infrared (FTIR) spectroscopy was applied to all samples, while solid-state 13C CP/MAS NMR was performed on the most effective adsorbents. Results revealed that materials with pH between 4.5 and 5.5 and comparatively elevated exchangeable calcium and sodium contents (such as acacia and eucalyptus bark, palm and alfa fibers, orange peel, almond shells, and date stones) achieved high LAS adsorption efficiencies (≥96.3 %), regardless of initial concentration. Elevated organic matter content (17–68.4 %) in all the investigated by-products promoted LAS retention, with all samples maintaining ≥48.6 %. Freundlich isotherm provided the best prediction for LAS, indicating heterogeneous, multilayer sorption, while the Langmuir model fit less accurately. Desorption remained below 12 % for all materials, with the most effective adsorbents showing <2 %, suggesting quasi-irreversible retention across a wide pH range (3.7–7.4). These findings highlight the potential of using agricultural by-products as cost-effective and sustainable bio-adsorbents for mitigating emerging pollutants like LAS in aquatic environments, thereby reducing ecological and human health risks
Simultaneous presence of antibiotics in the environment: competition for soil adsorption sites and risk mitigation by bioadsorbents
(Royal Society of Chemistry, 2025-09-30) Cela Dablanca, Raquel; Míguez González, Ainoa; Barreiro Buján, Ana; Rodríguez López, Lucía; Arias Estévez, Manuel; Núñez Delgado, Avelino; Álvarez Rodríguez, Esperanza; Fernández Sanjurjo, María J.; Universidade de Santiago de Compostela. Departamento de Edafoloxía e Química Agrícola
Antibiotics are poorly absorbed and largely excreted through feces and urine, entering the environment. Although previous research focused on the adsorption of cefuroxime (CFX), amoxicillin (AMX) and azithromycin (AZM) onto soils and bio-adsorbents, the effect of the simultaneous presence of these antibiotics was not investigated, although being common in the environment. Hence, this work studied the adsorption of these antibiotics when added together to six soils and to three bio-adsorbents (oak ash, pine bark and mussel shell), and compared the results with those obtained for each antibiotic individually in previous studies. AZM exhibited the highest adsorption on soil. AMX adsorption by soils increased in the presence of CFX and AZM (from 76% to 88%). However, the adsorption of the other two antibiotics decreased in ternary systems: CFX dropped from 99% to 96%, and AZM from 100% to 42%. Regarding bio-adsorbents, oak ash demonstrated the highest adsorption efficiency for the three antibiotics, exceeding 90% in the ternary system. Pine bark and mussel shell showed lower adsorption efficiencies. The Freundlich model best described adsorption in soils, while only mussel shell fits well this model among the bio-adsorbents. Desorption from soils increased when antibiotics were applied simultaneously, with AMX showing the highest desorption. For bio-adsorbents, desorption was higher in the single-compound systems. Overall, AMX adsorption was enhanced by the presence of CFX and AZM, while both CFX and AZM adsorption were negatively affected by the presence of other antibiotics, suggesting competitive interactions
Removal of the ionophore antibiotic narasin using vegetal materials as bioadsorbents
(Royal Society of Chemistry, 2026-01-21) Hamdi, Samiha; Issaoui, Manel; Míguez González, Ainoa; Cela Dablanca, Raquel; Hammami, Sonia; Barreiro Buján, Ana; Fernández Sanjurjo, María J.; Álvarez Rodríguez, Esperanza; Núñez Delgado, Avelino; Universidade de Santiago de Compostela. Departamento de Edafoloxía e Química Agrícola
The occurrence of ionophore antibiotics, particularly narasin (NAR), in the environment, has recently become a matter of concern because of their widespread use, high eco-toxicity, and environmental persistence. This study assessed the adsorption–desorption characteristics of NAR onto a variety of low-cost by-products using batch-type experiments. Fourier transform infrared (FTIR) spectroscopy was performed on all samples, whereas solid-state 13C CP/MAS NMR analyses were undertaken on the six most effective adsorbents as well as on the three least efficient ones. The results show that, at low concentrations of antibiotic added (5–10 µmol L−1), adsorption remained low, not exceeding 25.33%. At the three lowest concentrations (5–20 µmol L−1), alfa, palm, and cactus fibers, as well as calcined coffee grounds exhibited adsorption rates always ≥65.12%. At concentrations ≥20 µmol L−1, adsorption increased in bioadsorbents with higher organic matter content, reaching up to 100% for eucalyptus bark at 100 µmol L−1. Adsorption data were adjusted to different models, with Freundlich presenting the best fit. No desorption was observed at low concentrations for most bioadsorbents, except for cactus and Mediterranean tapeweed fibers, as well as for raw and calcined coffee grounds, while it increased with higher concentrations (above 20 µmol L−1), but generally remained below 10%, except for calcined coffee grounds and cactus fiber, where it reached 10.48% and 14.64%, respectively, at 100 µmol L−1 of NAR added. All these results indicate that NAR is strongly retained on the tested bioadsorbents, suggesting that the ecological risks associated with this pollutant can be mitigated using these bioadsorbents
Photodegradation of Ciprofloxacin, Clarithromycin and Trimethoprim: Influence of pH and Humic Acids
(MDPI, 2021-05-21) Rodríguez López, Lucía; Cela Dablanca, Raquel; Núñez Delgado, Avelino; Álvarez Rodríguez, Esperanza; Fernández Calviño, David; Arias Estévez, Manuel; Universidade de Santiago de Compostela. Departamento de Edafoloxía e Química Agrícola
In view of the rising relevance of emerging pollutants in the environment, this work studies the photodegradation of three antibiotics, evaluating the effects of the pH of the medium and the concentration of dissolved organic matter. Simulated light (with a spectrum similar to that of natural sunlight) was applied to the antibiotics Ciprofloxacin (Cip), Clarithromycin (Cla) and Trimethoprim (Tri), at three different pH, and in the presence of different concentrations of humic acids. The sensitivity to light followed the sequence: Cip > Cla > Tri, which was inverse for the half-life (Tri > Cla > Cip). As the pH increased, the half-life generally decreased, except for Cla. Regarding the kinetic constant k, in the case of Cip and Tri it increased with the rise of pH, while decreased for Cla. The results corresponding to total organic carbon (TOC) indicate that the complete mineralization of the antibiotics was not achieved. The effect of humic acids was not marked, slightly increasing the degradation of Cip, and slightly decreasing it for Tri, while no effect was detected for Cla. These results may be relevant in terms of understanding the evolution of these antibiotics, especially when they reach different environmental compartments and receive sunlight radiation
Occurrence of Nine Antibiotics in Different Kinds of Sewage Sludge, Soils, Corn and Grapes After Sludge Spreading
(Frontiers Media, 2022-09-26) Barreiro Buján, Ana; Cela Dablanca, Raquel; Nebot García, Carolina; Rodríguez López, Lucía; Santás Miguel, Vanesa; Arias Estévez, Manuel; Fernández Sanjurjo, María J.; Núñez Delgado, Avelino; Álvarez Rodríguez, Esperanza; Universidade de Santiago de Compostela. Departamento de Edafoloxía e Química Agrícola; Universidade de Santiago de Compostela. Departamento de Química Analítica, Nutrición e Bromatoloxía
The huge worldwide use of antibiotics triggers the accumulation of these substances in sludge from wastewater treatment plants (WWTP) and the possible contamination of soils amended with it, as well as of crops growing in these soils. In this work we analyzed the presence of the antibiotics amoxicillin (AMO), cefuroxime (CEF), ciprofloxacin (CIP), clarithromycin (CLA), levofloxacin (LEV), lincomycin (LIN), norfloxacin (NOR), sulfadiazine (SUL), and trimethoprim (TRI), in sludge from different WWTPs in Galicia (NW Spain), as well as in sludge technically treated by waste-managers, in soils where treated sludge was applied, and in crops (corn and vineyard) growing in the amended areas. The antibiotics were quantified by means of high resolution HPLC-mass-chromatography. The results indicate that almost all the sludge samples contained antibiotics, being ciprofloxacin and levofloxacin the most abundant reaching maximum values of 623 and 893 ng/g, respectively. The sludge treatment significantly reduced the number and the concentrations of antibiotics. In 12% of the soil samples where sludge was applied, some antibiotics were detected, but always in small concentrations. Regarding the crops, no antibiotic was detected in the roots, stalk, leaves and grain of corn, neither in grapes sampled in vineyards. It can be concluded that the treatments currently applied in the WWTPs under study are not totally effective in removing antibiotics from the sludge, although the findings of this research suggest that the additional specific treatment of the sludge derived from these WWTPs is effective in reducing the risk of environmental pollution due to a variety of antibiotics, and specifically in the case of soils amended with these organic materials and crops growing on it.
Color measurements as a reliable method for estimating chlorophyll degradation to phaeopigments
(Springer, 2011-07) Sanmartín Sánchez, Patricia; Villa, F.; Silva Hermo, Benita María; Cappitelli, F.; Prieto Lamas, Beatriz; Universidade de Santiago de Compostela. Departamento de Edafoloxía e Química Agrícola
The application of biocides is a traditional method of controlling biodecay of outdoor cultural heritage. Chlorophyll degradation to phaeopigments is used to test the biocidal efficacy of the antimicrobial agents. In the present study, the usefulness of color measurements in estimating chlorophyll degradation was investigated. An aeroterrestrial stone biofilm-forming cyanobacterium of the genus Nostoc was chosen as test organism, comparing its different behaviour in both planktonic and biofilm mode of growth against the isothiazoline biocide Biotin T®. Changes in A435 nm/A415 nm and A665 nm/A665a nm and in the chlorophyll a and adenosine triphosphate (ATP) cell content were compared with the variations in the CIELAB color parameters (L*, a*, b*, C*ab and hab). Our findings showed that both the phaeophytination indexes are useful in describing degradation of chlorophyl a to phaeopigments. Moreover, the CIELAB color parameters represented an effective tool in describing chlorophyll degradation. L* CIELAB parameter appeared to be the most informative parameter in describing the biocidal activity of Biotin T® against Nostoc sp. in both planktonic and biofilm mode of growth.
Recovery of the traditional colours of painted woodwork in the Historical Centre of Lugo (NW Spain)
(Elsevier, 2011-07) Prieto Lamas, Beatriz; Sanmartín Sánchez, Patricia; Pereira Pardo, Lucía; Silva Hermo, Benita María; Universidade de Santiago de Compostela. Centro Interdisciplinar de Investigación en Tecnoloxías Ambientais (CRETUS); Universidade de Santiago de Compostela. Departamento de Edafoloxía e Química Agrícola
The rehabilitation of the degraded medieval quarter of A. Tinería, in Lugo (NW Spain) included the recovery of the traditional colours on plasters and woodwork. To achieve this aim, the paint materials on wooden elements (window frames and doors) have been characterised firstly by means of colour measurements on site, with a portable solid reflection spectrophotometer, and secondly by pigment analysis of paint samples, using OM, SEM-EDS and MRS. The results revealed that the predominant colour in the cityscape of the 19th and early 20th century was red, and that the paints contained red ochre of a local origin, in some cases with the addition of red lead. Other minor colours were identified as well: blue paints contained ultramarine blue or Prussian blue, yellow paints contained lead oxide and green paints were based on copper pigments or on a mixture of Prussian blue and yellow lead oxide. Extenders like barium sulfate, gypsum or calcite were often added to the paints. Finally, the turquoise paints were applied in recent times, as titanium white and phtalocyanine green (both industrially synthesised in the 20th century) were identified in their composition. These results have contributed to the elaboration of the Colour Plan of the Historic Centre of Lugo. The rehabilitation of A. Tinería is still ongoing and has received one of the United Nations’ International Dubai awards in 2008, recognizing good practices and local leadership
Color of cyanobacteria: some methodological aspects
(Optica Publishing Group, 2010-04-01) Prieto Lamas, Beatriz; Sanmartín Sánchez, Patricia; Aira Touzón, Noelia; Silva Hermo, Benita María; Universidade de Santiago de Compostela. Centro Interdisciplinar de Investigación en Tecnoloxías Ambientais (CRETUS); Universidade de Santiago de Compostela. Departamento de Edafoloxía e Química Agrícola
Although the color of cyanobacteria is a very informative characteristic, no standardized protocol has, so far, been established for defining the color in an objective way, and, therefore, direct comparison of experimental results obtained by different research groups is not possible. In the present study, we used colorimetric measurements and conventional statistical tools to determine the effects on the measurement of the color of cyanobacteria, of the concentration of the microorganisms and their moisture content, as well as of the size of the target area and the minimum number of measurements. It was concluded that the color measurement is affected by every factor studied, but that this can be controlled for by making at least 10 consecutive measurements=9:62 cm2 at different randomly selected points on the surface of filters completely covered by films of cyanobacteria in which the moisture contents are higher than 50%
Conversion of a digital camera into a non-contact colorimeter for use in stone cultural heritage: the application case to Spanish granites
(Elsevier, 2014-10) Sanmartín Sánchez, Patricia; Chorro Calderón, Elísabet; Vázquez Nión, Daniel; Martínez Verdú, Francisco Miguel; Prieto Lamas, Beatriz; Universidade de Santiago de Compostela. Centro Interdisciplinar de Investigación en Tecnoloxías Ambientais (CRETUS); Universidade de Santiago de Compostela. Departamento de Edafoloxía e Química Agrícola
In this study, a digital CMOS camera was calibrated for use as a non-contact colorimeter for measuring the color of granite artworks. The low chroma values of the granite, which yield similar stimulation of the three color channels of the camera, proved to be the most challenging aspect of the task. The appropriate parameters for converting the device-dependent RGB color space into a device-independent color space were established. For this purpose, the color of a large number of Munsell samples (corresponding to the previously defined color gamut of granite) was measured with a digital camera and with a spectrophotometer (reference instrument). The color data were then compared using the CIELAB color formulae. The best correlations between measurements were obtained when the camera works to 10-bits and the spectrophotometric measures in SCI mode. Finally, the calibrated instrument was used successfully to measure the color of six commercial varieties of Spanish granite.
Measuring de the color of granite rocks. A proposed procedure
(Wiley, 2010) Prieto Lamas, Beatriz; Sanmartín Sánchez, Patricia; Silva Hermo, Benita María; Martínez Verdú, Francisco; Universidade de Santiago de Compostela. Centro Interdisciplinar de Investigación en Tecnoloxías Ambientais (CRETUS); Universidade de Santiago de Compostela. Departamento de Edafoloxía e Química Agrícola
In spite of color being one of the physicochemical parameters most commonly used to characterize ornamental stone, there is yet no standardized protocol for measuring this parameter. Such a protocol is of particular importance for characterizing the color of heterogeneous surfaces, as in the case of granite. The aim of the present study was to determine the minimum area and the number of measurements required to characterize the color of granite rocks. A spectrophotometer and a tristimulus colorimeter, were used to measure the color of granite samples, and the measurements were expressed in CIE L*a*b* color system units. Three parameters were considered as variable factors: the type of rock (Labrador Claro, Grissal, Rosa Porriño, and Blanco Cristal), surface finish (polished, honed, sawn, and flamed), and target area (circular apertures of diameter 5, 8, 10, and 50 mm). The results of the application of multivariate analysis of variance and of the classical CIELAB formula and CIE L*a*b*-based color-difference formulae (i.e., CIE94 and CIEDE2000) to the data revealed that, although all considered factors affected the minimal area and the number of measurements required, the different circular apertures of both the instruments can be disregarded if the number of measurements and area recommended in this study are used
Relationship between color and pigment production in two stone biofilm-forming cyanobacteria (Nostoc sp. PCC 9104 and Nostoc sp. PCC 9025)
(Taylor and Francis, 2010-04-26) Sanmartín Sánchez, Patricia; Aira Touzón, Noelia; Devesa Rey, Rosa; Silva Hermo, Benita María; Prieto Lamas, Beatriz; Universidade de Santiago de Compostela. Centro Interdisciplinar de Investigación en Tecnoloxías Ambientais (CRETUS); Universidade de Santiago de Compostela. Departamento de Edafoloxía e Química Agrícola
Previous studies have provided evidence that color measurements enable on site quantification of superficial biofilms, thereby avoiding the need for sampling. In the present study, the efficiency of color measurements to evaluate to what extent pigment production is affected by environmental parameters such as light intensity, combined nitrogen and nutrient availability, was tested with two cyanobacteria, Nostoc sp. strains PCC 9104 and PCC 9025, which form biofilms on stone. Both strains were acclimated, in aerated batch cultures for 2 weeks, to three different culture media: BG-11, BG-110, and BG-110/10 at either high or low light intensity. The content of chlorophyll a, carotenoids, and phycocyanins was measured throughout the experiment, together with variations in the color of the cyanobacteria, which were represented in the CIELAB color space. The results confirmed that the CIELAB color parameters are correlated with pigment content in such a way that variations in the latter are reflected as variations in color
Spectrophotometric color measurement for early detection and monitoring of greening on granite buildings
(Taylor & Francis, 2012-03-28) Sanmartín Sánchez, Patricia; Vázquez Nión, Daniel; Silva Hermo, Benita María; Prieto Lamas, Beatriz; Universidade de Santiago de Compostela. Centro Interdisciplinar de Investigación en Tecnoloxías Ambientais (CRETUS); Universidade de Santiago de Compostela. Departamento de Edafoloxía e Química Agrícola
This paper addresses the detection and monitoring of the development of epilithic phototrophic biofilms on the granite façade of an institutional building in Santiago de Compostela (NW Spain), and reports a case study of preventive conservation. The results provide a basis for establishing criteria for the early detection of phototrophic colonization (greening) and for monitoring its development on granite buildings by the use of color changes recorded with a portable spectrophotometer and represented in the CIELAB color space. The results show that parameter b* (associated with changes of yellowness-blueness) provides the earliest indication of colonization and varies most over time, so that it is most important in determining the total color change. The limit of perception of the greening on a granite surface was also established in a psycho-physical experiment, as Δb*: +0.59 CIELAB units that correspond, in the present study, to 6.3 μg of biomass dry weight cm−2 and (8.43 ± 0.24) × 10−3 μg of extracted chlorophyll a cm−2
Rapid evaluation of three biocide treatments against the cyanobacterium Nostoc sp. PCC 9104 by color changes
(Springer, 2015) Sanmartín Sánchez, Patricia; Villa, Federica; Polo, Andrea; Silva Hermo, Benita María; Prieto Lamas, Beatriz; Cappitelli, Francesca; Universidade de Santiago de Compostela. Centro Interdisciplinar de Investigación en Tecnoloxías Ambientais (CRETUS); Universidade de Santiago de Compostela. Departamento de Edafoloxía e Química Agrícola
Repeated short–term exposures to: (1) a commercial isothiazoline biocide (Biotin T®), (2) constant temperature (37 °C) and (3) UV-C germicidal irradiation (254 nm) on planktonic culture of an aeroterrestrial cyanobacterium of the genus Nostoc was carried out to assess (1) the effectiveness of the three trial treatments, referred to here as biocide strategies, and (2) the usefulness of CIELAB color coordinates (L*, a*, b*, C*ab, and hab) in monitoring their effectiviness. After each exposure, spectrophotometric measurements of chlorophyll-a, phycobiliproteins (phycocyanin PC, allophycocyanin APC, and phycoerythrin PE), and total carotenoids were conducted together with CIELAB color measurements and the adenosine triphosphate (ATP) assay. In terms of effectiveness of biocide treatments, Biotin T® was the most effective, followed by UV-C irradiation. Constant 37 °C temperature showed no biocidal effect, as ATP, chlorophyll-a, phycocyanin, and allophycocyanin values increased. Results showed that L*, a*, and hab CIELAB parameters could be usefully used to monitor the effectiveness of these three biocide strategies being all the CIELAB color coordinates significantly correlated with chlorophyll-a, phycocyanin, allophycocyanin, and ATP contents. In particular, for the first time, linear regression equations were calculated to predict chlorophyll-a and ATP from parameters L* and a*, and phycocyanin and allophycocyanin from parameters L* and hab, obtaining values of adjusted R 2 close to 0.9. Future considerations will include the application of this technique to cyanobacterial biofilms present on stone surfaces, since the evaluation presented in this study is limited to planktonic cultures
Characterization and dyeing potential of colorant-bearing plants of the Mayan area in Yucatan Peninsula, Mexico
(Elsevier, 2015-03-15) Chan Bacab, Manuel Jesús; Sanmartín Sánchez, Patricia; Camacho Chab, Juan Carlos; Palomo Ascanio, Kahlia Beatriz; Huitz Quimé, Hesby Emmanuel; Ortega Morales, Benjamin Otto; Universidade de Santiago de Compostela. Centro Interdisciplinar de Investigación en Tecnoloxías Ambientais (CRETUS); Universidade de Santiago de Compostela. Departamento de Edafoloxía e Química Agrícola
Natural dyes are receiving increasing attention from researchers and manufacturers, given its perceived eco-friendly nature. Yet, adjunct agents known as mordants that help bond the molecules of the fabric being dyed and the colorant used to dye it are often toxic. There is scant published information describing the dyeing potential and toxicity of colorant-bearing plants and the dye uptake with respect to the mordant treatments. A preliminary survey based on a range of sources of information showed that of the Yucatan peninsula harbors 23 plants showing dyeing properties. Four of them (Justicia spicigera, Bixa orellana, Bougainvillea glabra and Rhoe discolor) were selected to extract their natural dyes, which were chemical and toxically characterized. B. orellana was successfully employed to dye the fabric, viz. ordinary cotton cloth, manta. The dye baths without mordant only present low toxicity, the J. spicigera and B. glabra dyes being the most toxic. The B. orellana dye was less toxic, although its toxicity is increased when mordants are used. Regarding color performances of the dyed fabrics, mordanting influenced the depth of the shades, improving dyeing and light fastness. Nevertheless, mordants had no significant effects on color values

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