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This paper reports the results of a study of biogenic Mn oxide minerals coating in a subsurface granite environment.This subterranean environment corresponds to galleries of a 16th century spring water tunnel dug throughout the granite bedrock located in Porto city (NW Portugal). Several techniques (XRD, FTIR, Raman, ICP-MS, TEM-EDS, FESEM-EDS, STEM-EDS and STXM-NEXAFS) were used to assess the mechanisms involved in the formation of manganese oxides, specifically birnessite and todorokite. These manganese oxides presented peculiar shapes, nano-dimensions, low degree of crystallinity, and high levels of some trace elements such as P, Ca, C, Al, Si, Ba and Zn. They were associated with large amounts of extracellular polymeric substances exuded by filamentous bacterial communities, which serve as nuclei for preferential precipitation of manganese oxides on the extracellular sheaths. Scientific assessment revealed that biological activity played a major role in the development of these manganese oxides.

The walls and ceiling of Altamira Cave, northern Spain, are coated with different coloured spots (yellow, white and grey). Electron microscopy revealed that the grey spots are composed of bacteria and bioinduced CaCO 3 crystals. The morphology of the spots revealed a dense network of microorganisms organized in well-defined radial and dendritic divergent branches from the central area towards the exterior of the spot, which is coated with overlying spheroidal elements of CaCO 3 and CaCO 3 nest-like aggregates. Molecular analysis indicated that the grey spots were mainly formed by an unrecognized species of the genus Actinobacteria. CO 2 efflux measurements in rocks heavily covered by grey spots confirmed that bacteria-forming spots promoted uptake of the gas, which is abundant in the cave. The bacteria can use the captured CO 2 to dissolve the rock and subsequently generate crystals of CaCO 3 in periods of lower humidity and/or CO 2. A tentative model for the formation of these grey spots, supported by scanning electron microscopy and transmission electron microscopy data, is proposed. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Aerobiology of caves is still in its infancy. At present, no clear information has been generated on the limits of acceptance of fungal spores in air which permit classification of the atmosphere of a cave as not dangerous for the conservation of rock-art paintings. We had the unique opportunity to visit and sample different caves in Spain and France, under different managements. We obtained a collection of data related with contamination episodes that permitted the formulation of a tentative index of fungal hazard in show caves. This is supported by the concentration of fungal spores in the cave air, the knowledge of the cave history and management, and a detailed survey of the different halls of the caves. The index classifies the risks into five categories: category 1 identifies a cave without fungal problems, category 2 is an alarm signal for caves, category 3 is a cave threatened by fungi, category 4 is assigned to a cave already affected by fungi, and category 5 is a cave with an irreversible ecological disturbance. This index, a working hypothesis, is launched to promote interest and forum discussion and should be validated by the scientific community after being updated with more surveys and cave analyses carried out under different managements and with different contamination episodes.

With today's leisure tourism, the frequency of visits to many caves makes it necessary to know about possible potentially pathogenic microorganisms in caves, determine their reservoirs, and inform the public about the consequences of such visits. Our data reveal that caves could be a potential danger to visitors because of the presence of opportunistic microorganisms, whose existence and possible development in humans is currently unknown.

[EN]: The present paper shows an interesting Optical Microscopy (OM) and Scanning Electron microscopy coupled with energy dispersive X-ray analysis (SEM/EDX) application to study degradation crust formation processes in Fort San Pedro, a historical building located at the colonial City of San Francisco de Campeche, México; and the Cathedral of Seville, at Seville, Spain. The results show that while in Seville the crusts are consequence of sulfur dioxide reaction whit calcareous stone, leading to gypsum crystal formation (CaSO4.2H2O), in San Francisco de Campeche, deterioration crust are consequence of natural recrystallization processes of CaCO3 induced by excessive environmental humidity., [ES]: En este trabajo se presenta una interesante aplicación de técnicas microscópicas, como microscopía óptica y la microscopía electrónica de barrido acoplada a un sistema de detección de Rayos X (SEM/EDX), para estudiar los procesos de formación de costras de deterioro del Baluarte de San Carlos en la ciudad de San Francisco de Campeche, México y la Catedral de la ciudad de Sevilla, España. Los resultados indican que mientras en la ciudad de Sevilla, las costras se componen principalmente de cristales de yeso (CaSO4.2H2O), como consecuencia de la reacción del dióxido de azufre atmosférico emitido por vehículos automotores con los componentes calcáreos de la piedra, en la ciudad de San Francisco de Campeche, son producto de procesos de disolución y recristalización de CaCO3, inducido por la excesiva humedad ambiental característica de climas tropicales.

The combustion of crude oil produces a wide range of pollutants, including gases, volatile organic compounds, polycyclic aromatic hydrocarbons, acid compounds (e.g., sulfuric acid), and soot. Several of these pollutants have been linked with the deterioration and blackening of monuments. The paper reports the results of an investigation on the causes of the soiling of cultural remains at important archaeological sites in the provinces of Khuzestan and Fars, in southern Iran, assumed to be an effect of the Persian Gulf oil well fires of 1991. Different analytical techniques were applied to characterize the mineralogical composition of the damage layers, investigate the deposition of atmospheric particles, measure the anion concentrations, and identify and quantify the carbon components. The results showed that the black deposits on the surfaces of the Iranian monuments considered are mainly microbiotic crusts produced by cyanobacterial growth. No evidence was found of the deposition of particulate matter (smoke) produced by the Kuwait oil fires during the Gulf War. © 2007 American Chemical Society.

A humic acid extracted from a chernozem soil was fractionated combining size exclusion chromatography and polyacrylamide electrophoresis (SEC-PAGE). Three fractions named A, B, and C+D, with different electrophoretic mobilities and molecular sizes (MS), were obtained and subsequently characterized by thermochemolysis and surface-enhanced Raman spectroscopy (SERS). The data confirmed that fraction A, with the higher MS, was more aliphatic than fractions B and C+D and, in turn, fractions with lower MS (B and C+D) denoted an enrichment in lignin residues. These structural features explain conformational changes when varying the pH in the humic fraction A and indicated that combination of the two techniques is a good approach for characterizing humic substances.

Humic acids (HA) from soils of very different origin and bioclimatic conditions (podzoluvisol, phasozem, chernozem, and ferralsol) were fractionated by coupling size-exclusion chromatography and polyacrylamide gel electrophoresis (tandem SEC-PAGE). From each HA, three fractions-A, B, and C+D, with different molecular sizes and electrophoretic mobilities-were obtained and analysed by thermochemolysis, the products being identified subsequently by gas chromatography/mass spectrometry. Regardless of HA origin, fraction A contained considerably more n-fatty acids and n-alkanes derived from plant waxes than did fractions B and C+D. Lignins accumulated mainly in fractions B and C+D. These results show that tandem SEC-PAGE allowed the separation of soil HA into fractions enriched in different structural components whose distribution was independent of HA genesis.

The organic species present in the aerosols of the Seville atmosphere, sampled at different periods of the year, under distinct traffic regimes, are presented. The compounds are related to incomplete fuel combustion in vehicular exhausts.

The paper reports the results of an investigation into the soiling on surfaces and reliefs at important Iranian archaeological sites. Samples of surface deposits and damage layers were collected from immovable cultural remains located in the provinces of Khuzestan and Fars, southern Iran. Different analytical techniques were applied in order to characterise the mineralogical composition of the damage layers, investigate the embedded atmospheric particles, measure the soluble salt concentration, and identify and quantify the carbon components. The results are presented, paying particular attention to the carbon fractions not linked to the carbonate substrate, but originated by biological agents and anthropogenic activities. The authors illustrate and discuss the quantitative data for non-carbonate carbon, composed of elemental and organic fractions, along with the organic composition of the soiling deposits.

En las últimas décadas la contaminación atmosférica ha provocado un aumento en la frecuencia de limpieza de los monumentos pétreos. Los métodos tradicionales de limpieza presentan problemas que se evitan mediante la limpieza con láser. Sin embargo se ha demostrado que este tipo de limpieza induce cambios cromáticos en la superficie tratada. En este trabajo se ha estudiado la influencia de los compuestos inorgánicos y orgánicos en estos cambios cromáticos. Igualmente se proponen mecanismos que explican este fenómeno. El estudio se ha realizado con muestras de costra negra de la basílica de San Dionisio en París, ya que el portal del transepto norte se limpió con láser en 1998 y se observó que la superficie limpia de la piedra apareció de color amarillo. Para el estudio de la influencia de los compuestos inorgánicos en los cambios cromáticos producidos por el láser se han utilizado los siguientes métodos: fluorescencia de rayos X, difracción de rayos X, microscopía electrónica de barrido-energía dispersiva de rayos X y espectroscopía Mössbauer. Los resultados obtenidos fueron, por una parte, que el ennegrecimiento de pigmentos de hematita producido por la irradiación con láser se debe a una reducción de la hematita original formándose magnetita. Por otra parte, el amarilleamiento de las piedras limpiadas con láser se puede deber a que en la superficie de la piedra quedan pequeñas partículas esféricas que no se han eliminado con el láser y que contienen compuestos de hierro. Para el estudio de los compuestos orgánicos en los cambios cromáticos producidos por el láser se ha utilizado cromatografía de gases-espectrometría de masas (CG/EM) y pirólisis-metilación-cromatografía de gases/espectrometría de masas (Py-CG/EM). Se ha estudiado la composición orgánica de la costra negra de la basílica de San Dionisio mediante Py-CG/EM para tener una primera aproximación de la composición orgánica de la muestra. Asimismo se realizó un estudio mucho más detallado, mediante la extrac

The genus Pectinatus is currently composed by two species, Pectinatus cerevisiiphilus and Pectinatus frisingensis, both asociated with beer spoilage. This study describes a novel isolate (strain B6) retrieved from a wastewater treatment plant collecting residues from a large number of wineries. Based on similarity analysis of 16S rRNA gene sequences, strain B6 belongs to the genus Pectinatus. Strain B6 is a strict anaerobe like other Pectinatus species and it presents non-motile, coccoid cells showing a slight oval shape. Strain B6 shows marked physiological differences with other Pectinatus species both in fatty acid composition and carbon source utilization. The most abundant fatty acids found in strain B6 were 18:1 (42.8%) and 16:0 (18.3%) representing a total of over 61% of fatty acids in this microorganism while these fatty acids represented 41.3% in P. cerevisiiphilus T and 2.4% in P. frisingensis T of their total. Fatty acid 15:0 was not significant in strain B6 and represented 28.6% and 13.3% for P. cerevisiiphilusT and P. frisingensisT, respectively. Strain B6 showed a faster growth rate and higher optimum temperature than its relatives P. cerevisiiphilus and P. frisingensis. Strain B6, P. cerevisiiphilus and P. frisingensis could be clearly differentiated by acid production tests from substrates such as esculine and gluconate, and the lack of acid production from rhamnose and fucose among others. G+C mol% content in strain B6 is 36.5%. Based on genotypic and phenotypic differences, strain B6 is proposed as a novel Pectinatus species, P. portalensis nov. sp. Both strain B6 and the two described species of Pectinatus grow on beers and wines. These results provide insights about the origin and reservoirs of Pectinatus species and spoiling alcoholic beverages.

Buildings and monuments act as repositories of airborne organic pollutants, which accumulate at the surfaces in zones frequently soaked by rainwater but are not washed out. In these areas thick black crust deposits can be found, which contribute to soiling of stone surfaces. The exposed building materials act as a non-selective surface, passively entrapping all deposited airborne particulate matter and organic compounds, which obviously modifies the composition of the materials present in the stone surface. Black crusts from different European monuments and buildings contain molecular markers that are characteristic of petroleum derivatives.

For more than five decades, exhaust emissions from gasoline-and diesel-powered vehicles contributed to the deterioration of the cathedral of Seville, particulary of stone and terracotta statues from the three western façade portals. This is due to the location of the main façade in a narrow street with intense traffic. A study on the organic composition of aerosols sampled at different periods of the year, under distinct traffic regimes, is presented. A strong correspondence between the lipids present in the cathedral black crusts and those of collected from urban aerosols was found.

The organic species present in the atmosphere comprise gases, lipis and particulate matter. These species are deposited and entrapped on the stone surface of monuments forming black crusts. The composition of the organic compounds present in black crusts form different European monuments were studied by tetramethyl ammonium hydroxide thermochemolysis and analysed bay gas chromatography in combination with mass spectrometry.

Biofilms are widely distributed in different areas of the Roman catacombs of St. Callixtus and Domitilla due to the abundance of mineral elements in the volcanic rock, high humidity and artificial lighting. Cyanobacteria are responsible for biofilm formation to which heterotrophic bacteria and fungi are associated. Barite (barium sulphate) was detected as secondary mineralization in altered volcanic rocks from both catacombs. Its spatial disposition suggests an origin related with the observed bacterial mats. Witherite (barium carbonate) precipitated in cultures of bacteria isolated from the two catacombs. This suggests a role of bacteria in the biogeochemical cycle of barium in terrestrial environments and, particularly, in the mobilization of barium from the volcanic rocks and its further sulphate precipitation.

The holy water fonts from the churches of Seville, Spain have a strong bacterial contamination. Coliforms, Enterobacteriaceae and other pathogenic bacteria are widely represented in the fonts investigated. Thirty out of the 37 different species isolated from holy waters are known human pathogens. The high bacterial contamination is related to human skin transmission and, probably, to misuse of the water.

In this paper we applied thermally assisted hydrolysis and methylation to a soil humic acid (HA) and their polyacrylamide gel electrophoresis (PAGE) fractions. The data indicates that PAGE fractionation of HA produces selectively enriched humic fractions in terms of major structural components (e.g. fatty acids, lignin units, etc.). Lignin components were mainly found in fraction b (medium electrophoretic mobility) of HA. Plant fatty acids were mainly distributed in fraction a (no electrophoretic mobility), and microbial lipids were distributed in all fractions, but the higher relative amounts appeared primarily associated with fractions b and c+d (high electrophoretic mobility).

The weathering of stone and masonry results, among other phenomena, in the formation of efflorescences, a deposit of salts not originally evident in the sound material, and composed of a variety of different hygroscopic salts, including carbonates, chlorides, nitrates, sulphates, etc. Thus the deteriorated areas of some monuments can be considered as extremely saline environments, at least in the efflorescences zones. These zones seemed to be a particular niche for investigating halotolerant and/or halophilic bacteria, but only recently a few reports appeared stressing the importanee of these types of bacteria. In this paper, bacteria were isolated from samples taken from the efflorescences originated in the Chapel of All Souls, cathedral of Jerez Spain, and cultured in media with increasing concentrations of halite or epsomite (up to 25 %). The most frequently isolated genus was Bacillus, followed by Staphylococcus, Kocuria, Micrococcus, Paenibacillus and Arthrobacter. The origin, occurrence and ecology of halotolerant and halophilic bacteria in monuments are discussed.

The active stalactites from Grotta del Cervi, Porto Badisco, southeastern Italy, were sampled to investigate the microbial communities present in these speleothems. Sampling was carried out in a transect about 150 m long in the central gallery, where numerous Gram-positive bacteria were isolated. Actinomycetes of the genus Streptomyces were the most abundant, followed by members of the genus Bacillus. Further isolates were assigned to the genera Amycolatopsis, Arthrobactcr, Agminyces, Micrococats, Noccmliopsis and Rhoclococcus of the order Actinomycetales. The ability of actinomycetes to colonize subterranean environments is discussed.

The Sierra de Cazorla, Jaen, Spain, is characterized by the presence of a number of shelters or smallcavities with important late prehistoric paintings,the so-called schematic rock art painting. The microbial population of the rocks supporting paintings from two shelters was investigated. Bacteria isolated from Cueva del Encajero triplicated the number of those isolated from Cueva de la Graja, as corresponded to a higher environmental humidity. However, the bacteria isolated from Cueva de la Graja were metabolically more active and able to use a higher number of carbon sources than those of Cueva del Encajero. As demonstrated by cluster analysis the microbial communities from both shelters are related, in spite of the different ecological conditions and geographical distribution.

Buildings and monuments act as repositories of airbome organic pol1utants, which accumulate at the surfaces fonning black crusts. The organic compounds present in the black crusts col1ected from monuments located in four European cities, Brussels, Dublin, Rome and Seville were investigated and compared with those extracted from a diesel soot. The methods used were evaporation/pyrolysis and simultaneous pyrolysis/methylation. A complex mixture of compounds was identified in the crusts, mainly n-alkanes, n-alkenes, acyclic isoprenoids, fatty acids, aliphatic dicarboxylic acids, alkylbenzenes, benzenepolycarboxylic acids, polycyclic aromatic hydrocarbons, thiophenes, furans, pyridines, quinolines, benzonitriles, etc. These compounds were produced from total or partial combustion of petroleum derivatives. Similar compounds were obtained from diesel soot indicating that traffic around the most out standing monuments contributes to a continuous blackening of its walls.

The Sierra de la Plata is an Aljibe yellow sandstone formation from the Acheulian period. There are a few shelters, some of them with rock art paintings. The most representative one, and subjected to anthropogenic pressure, is that of Atlanterra, situated in a residential area. This shelter contains some rock art paintings made with iron oxides. The bacteria present in these paintings were isolated and identified using an automatic method: fatty acid methyl esters profiling. Most of the bacteria belong to the Bacillus genus, B. megaterium being the most abundant species. The isolated strains are able to reduce hematite. This is significant due to the fact that Fe(III)-(hydr)oxides are the most abundant pigments in rock art.

The black deposit coating the ceiling and walls of Cueva del Encajero, a cavity with rock art was investigated. Thermally assisted hydrolysis and methylation revealed that the material is mainly composed of methylated fatty acids, aliphatic dicarboxylic acids, benzene-carboxylic acids and phenolic acids. Their comparison with humic acid-like fractions from fresh olive mill waste waters and aged sludge obtained from an evaporation pond indicates that this material is totally compatible with a plant origin. It is suggested that the black deposit derives from the decomposition of olives from non harvested olive trees growing on the surface, above the cave.

Soil humic acid fractionated by polyacrylamide gel electrophoresis yield four fractions: a, b, and c+d. Lignin samples runs as a single band and have the same electrophoretic mobility than fraction b of humic acid. Degraded lignin also yield fraction c+d. Model phenolic polymers and fungal melanins were mainly distributed into fractions equivalent to fractions b and c+d of humic acids. These data confirms those obtained using other analytical methods.

Thermally assisted hydrolysis and methylation (THM) with tetramethylammonium hydroxide (TMAH) of milled beech leaf litter was used to investigate the behaviour of polysaccharides, lipids and lignin components in complex organic matrices. THM at 300 °C produced a limited fragmentation of lignin derivatives and the relative proportion of fatty acid methyl esters increased with respect to aromatic compounds when compared with THM at 500 °C. Polysaccharide pyrolysis products were minor compounds at both temperatures. In addition, three different procedures for TMAH reaction at 300 °C were tested. Method A consisted in the application of TMAH solution to the sample, drying with a N2 flow and immediate insertion in the pyrolyzer. In method B the sample plus TMAH was sonicated for 30 min. In method C the sample was maintained with TMAH for 48 h at room temperature. It was shown that a prolonged time of reaction and or disruption of structures by sonication and more intensive mixing with TMAH increases the yield of evolved products. Therefore, it is proposed that a standardization of the pretreatment procedure with TMAH is needed in order to compare results obtained by different authors.

Dissolved organic matter from dripping waters collected in the cave of Altamira was studied by thermally assisted hydrolysis and methylation with tetramethylammonium hydroxide and was discovered to be composed of fatty acids and lignin derivatives. A water-soluble extract from the top soil also showed similar compounds, although in different percentages, suggesting that soil organic matter and bacterial cell lipids are likely the origin of the organic carbon found in dripping waters.

Humic acids (HAs) from four soils were fractionated by size exclusion chromatography (SEC) on Sephadex G-75. Three fractions were obtained in all humic acids, collected and assayed by polyacrylamide gel electrophoresis (PAGE). The unfractionated HA from each soil was used as reference. Each chromatographic fraction formed one electrophoretic zone corresponding closely to one band of the reference sample with some admixture of the fractions preceding or following. The results indicate that fractionation of HAs by tandem SEC-PAGE can be successfully used for obtaining fractions of reduced polydispersity and different electrophoretic mobilities. Pyrolysis/methylation-gas chromatography-mass spectrometry of the full size preparations of HA and fractions with exactly defined molecular size and electrophoretic mobility showed a different distribution in humic components, mainly lipids, lignin derivatives and N-containing compounds.

Fifteen different tropane alkaloids and derivatives were identified by GC-MS in various plant organs of Atropa baetica. The main root and leaves displayed the largest number of tropane alkaloids, most of which were also present in lateral roots. In contrast, only five of these alkaloids appeared in stem tissue. Quantitative analysis by HPLC showed the presence of the two major tropane alkaloids, atropine and scopolamine, in all the samples studied. Atropine was more abundant, with the highest concentration in the main root (ca. 10.0 mg/g dry wt) followed by leaves (ca. 3.0 mg/g dry wt); scopolamine was present in highest concentration in the main root (0.6 mg/g dry wt) followed by leaves (0.4 mg/g dry wt). The lowest concentrations of these compounds were detected in stem tissue, followed by the lateral roots. The main root constitutes the major tropane alkaloid storage site; moreover, the distribution of these compounds does not appear to be organ dependent. These latter two characteristics are in contrast to closely related Atropa genera.

Soil samples from the A horizon of an Eutrochrept under spruce forest and permanent grass were fractionated into clay-, silt- and sand-size separates. Humic acids extracted from each fraction were analysed by pyrolysis-gas chromatography-mass spectrometry. Protection of functional groups by simultaneous pyrolysis and methylation yielded pyrolysates in which methyl esters of fatty acids, aliphatic dicarboxylic acids, abietic acids, phenolic acids and benzenecarboxylic acids were represented. However, methylation was not complete, and unmethylated compounds were also present. Spectra showed differences in humic acid composition between size separates as well as across land use regimes. The abundance of lignin-derived pyrolysis products increased with decreasing particle size, and was greater in soil under spruce than in soil under grass. Also, the lipid components differed, with hexadecanoic and docosanoic acid methyl esters being the dominant compounds in humic acids from soil under spruce and hexadecanoic and octadecanoic acid methyl esters in the humic acids from grassland. A good correlation was found between previous 13C NMR and wet chemical data and pyrolysis data, indicating that pyrolysis-methylation can be used for fast detailed chemical characterization of humic acids extracted from size separates.

Limestone and weathering crusts have been studied at the major cathedrals of Sevilla, in southwestern Spain, and Mechelen, in northern Belgium. These cities have very different climatic and environmental conditions. The deterioration characteristics of the limestone in both localities have been compared. Detailed petrographical characterization was carried out for the different building stones, including restoration materials. The bulk and trace inorganic composition of the stones and crusts was assessed, and the leachable ions were analyzed, while elemental concentration profiles with depth were studied with electron microprobe analysis. The organic compounds in the black weathering crusts have also been studied and compared. In the different types of limestone, the deterioration is largely influenced by the petrographie characteristics of the stone. Gypsum crusts from Mechelen and Sevilla show variable textures, even on the same stone types. Sulfatation of calcite provides Ca for the gypsum crusts. Except fora part of the Sr and Fe fractions in the crust, all other elements may be of external origin. Concentrations of the various elements are more or less comparable in crusts from Mechelen and Sevilla. External inorganic particles consist of fly ash, quartz, clay, and glauconite. Most of the organic material appeared to be of anthropogenic origin, due to combustion processes, while a minor fraction originated from cuticular waxes of higher plants.

Hoy en día, existe una gran preocupaclOn en la sociedad en todo lo referente a la conservación del patrimonio cultural e histórico que ha llegado hasta nuestros días. Es evidente que, para poder abordar adecuadamente un proceso de conservación o restauración, es necesario efectuar previamente un estudio del material deteriorado, así como de las causas y mecanismos que han ocasionado (u ocasionan) la alteración. Esto obliga a un análisis exhaustivo del material, de los agentes causantes de la alteración y de los productos que se hayan podido formar como consecuencia de la interacción entre los elementos agresivos y el material original. En los últimos años, el deterioro de edificios y monumentos históricos es uno de los problemas que más está sensibilizando a la sociedad. Los edificios y monumentos están sometidos a la acción contínua de los agentes atmosféricos (acción mecánica), animales y plantas (acción biológica) y de todos los compuestos que se encuentran en la afmósfera que los rodea y que puedan interaccionar con ellos (acción química). Rosvall (1988) cuantificó los daños en los materiales empleados en edificios históricos y monumentos, tales como piedras, ladrillos, tejas, morteros, vidrieras, etc., concluyendo que la contaminación atmosférica era una importante fuente de pérdidas económicas en áreas urbanas. La piedra se ha utilizado ampliamente desde hace siglos como material básico en la construcción de obras monumentales. Las estructuras de piedra, aún siendo más duraderas que las de otros materiales están sometidas al ataque por agentes naturales, si bien los daños se producen generalmente en el transcurso de largos períodos de tiempo. Sin embargo, las actividades de la sociedad industrializada han contribuido a una aceleración drástica de la degradación de estructuras pétreas pertenecientes a obras históricas, hasta el punto que, en muchos casos, es posible percibir claramente en una sola generación, la alteración de monumentos construidos hace centuri

The organic compounds present in weathered surfaces of building stones were investigated using simultaneous pyrolysis/methylation. The method consists of the derivatization of the sample with the alkylating reagent tetramethylammonium hydroxide. Tetramethylammonium salts of organic acids can be converted to methyl ester and the corresponding byproduct in the pyrolysis unit. Hydroxyl groups are also methoxylated. The protection of functional groups permits direct and complete analysis of samples by pyrolysis. No time-consuming solvent extractions, concentrations, derivatizations, and other manipulations which imply the possibility of cross-contamination, are required. The data obtained by solvent extraction and subsequent gas chromatography-mass spectrometry analysis are similar to those obtained by pyrolysis/methylation, proving that this method is an analytical procedure of great sensitivity for investigating organic compounds in inorganic matrices.

Aquatic and terrestrial humic substances consist of two main fractions: fulvic acid and humic acid. These fractions are operationally defined, based on solubil- ity in alkalis and acids. This lack of a proper chemical definition has resulted in misinterpretations, and despite humus studies having a history of more than 200 years, their nature is still unknown and subject to debate.

Pyrolysis has been used for the last ten years to study the chemical nature of humic substances. However, obtaining data is hampered by analytical limitations. One of these is that carboxylic acids other than fatty acids are not usually present amongst pyrolysis products. To overcome this problem, a novel method - pyrolysis/methylation - is applied. Simultaneous pyrolysis/derivatization with tetramethylammonium hydroxide protects the carboxyl groups by formation of methyl esters. At the same time, partial methylation of hydroxyl groups occurs. This method permits the identification of a suite of carboxyl-containing aromatic and aliphatic compounds, not previously observed in conventional pyrolysis, providing useful information on the biodegradation processes of plant materials leading to macromolecular humic substances. | Pyrolysis has been used for the last ten years to study the chemical nature of humic substances. However, obtaining data is hampered by analytical limitations. One of these is that carboxylic acids other than fatty acids are not usually present amongst pyrolysis products. To overcome this problem, a novel method-pyrolysis/methylation - is applied. Simultaneous pyrolysis/derivatization with tetramethylammonium hydroxide protects the carboxyl groups by formation of methyl esters. At the same time, partial methylation of hydroxyl groups occurs. This method permits the identification of a suite of carboxyl-containing aromatic and aliphatic compounds, not previously observed in conventional pyrolysis, providing useful information on the biodegradation processes of plant materials leading to macromolecular humic substances.

Three Spirulina and five eukaryotic algal food products available in the Spanish market have been extensively studied. Results are given for their gross chemical composition (water content, crude protein, total carbohydrates, lipids, nucleic acids etc.) and contents of macrominerals, trace elements, fatty acids, amino acids and neutral sugars. The results are compared to those from other studies on natural or laboratory-produced populations. An overall nutritional and toxicological evaluation of these products is included.

Pyrolysis-gas chromatography/mass spectrometry was used to study the organic compounds present in weathered building materials from historic buildings and monuments. Three very different materials were investigated: a black layer from a terracotta statue from the Pardon Gate, Cathedral of Seville, Spain; a green layer found beneath a black sulphated crust from the Cathedral of Seville; and a black coating covering the stones of the Old Church of Delft, The Netherlands. From a general pattern in which n-alkanes and polycyclic aromatic hydrocarbons were the main components of black sulphated crust (as exemplified by the layer covering the terracotta statue), biogenic inputs could be easily recognized by study of specific markers (as denoted the contribution of the cyanobacterium Phormidium sp. to the green layer). Also an odd input, as in the case of the tar constituting the black coating of the stones of the Dutch church, was readily segregated. The results obtained indicate that analyticalpyrolysis may be used as a first approach for analysis of organic matter within mineral matrices in cultural properties.

After separation of the hymatomelanic acid fraction more lipid components can be recovered from humic acids by Soxhlet extraction with other solvents than ethanol (i.e., methylene chloride-methanol). The composition of these remaining mixtures has been investigated on the humic acids of three soils encompassing different properties in terms of pH, carbon content and associated vegetation (a Typic Xerochrept, a Typic Rendoll and a Typic Xerorthent). The hymatomelanic acid fraction of these samples has been studied elsewhere (ref. 1). Unsubstituted fatty acids generally predominate in both successive extracts, although distinct distributions are characteristics in each case. Important qualitative differences have been observed for other components, namely steroidal ketones and hydroxy acids.