– Novel mineralogical techniques for preservation of national monuments

Humidity, environmental pollution, cleaning with aggressive products for the chemical composition of the rock, etc. give rise to the appearance of salts which cause stone decomposition, paint coats detachment, dust accumulation, etc.

The treatments used up to now to deal with the problem have been directed, almost exclusively, to preserve the beauty of the affected monument, assuming, with an almost fatalist attitude, that the damage will go on as an effect of passing of time. European experts joint in the SALTCONTROL project have collaborated in a new work line to deal with the problem: Blocking inside the stone the mineral salt crystallisation process that ends up destroying it.

One of the works carried out in the framework of SALTCONTROL is the doctoral thesis Damage prevention due to salt crystallisation in national heritage through the use of crystallisation inhibitors, read by Encarnacion Maria Ruiz Agudo, under the supervision of Prof. Carlos Manuel Rodriguez Navarro; as well as several papers published by scientific journals such as Journal of Physical Chemistry, Environmental Geology, Scanning y Journal of the Japanese Association for Crystal Growth.

According to Ruiz Agudo (Centro Andaluz del Medio Ambiente – Department of Mineralogy and Petrology of the University of Granada) ornamental porous materials damage due to salt attack is one of the most aggressive alteration mechanisms that affect constructed heritage. In the last decades, we have developed different methods to prevent or reduce the damage due to salt crystallisation in ornamental rock pores, almost all with little success.

The thesiss research line and the above mentioned papers have followed the recent techniques that intend to use additives to modify the crystallisation process and prevent or reduce the damage produced in the rock. Up to now, most of the works in this field have assessed the efficiency of these treatments in slightly soluble salts, such as calcium and barium sulphates. The thesis has proved the effectiveness of this type of treatment in highly soluble salts, such as sodium and magnesium sulphates, as well as sodium nitrate, which can usually be found in historic buildings.

The research work has been applied to the case of the effects of these treatments in the rock extracted in Santa Pudias quarries (Escuzar, Granada), used in the construction of Renaissance buildings in Granada such as the Monastery of San Jeronimo, the Cathedral or the Royal Chapel. These buildings show strong alteration phenomenon due to crystallisation in sodium sulphate, magnesium and sodium nitrate.

The work has conducted to the carrying out of salt crystallisation tests in laboratory, which simulate alteration processes due to salt crystallisation in the bases on historic buildings walls. Later,’ says Ruiz Agudo, ‘we prepared a method for the implementation of the treatment developed in practical cases of ornamental stone materials conservation. Finally, in a last phase of development of the research project, we applied such treatment in pilot areas on the Monastery of San Jeronimo (Granada), where there had been important problems due to salt crystallisation.

The final result of the research work proposes the application of low-cost additives, which have proved to be very effective in the fight against the problems of ornamental porous materials. On the other hand, the research work involves a methodology to deal with the study of damage caused by salts and the selection of the most adequate type of additive for a specific substrate and type of salt. The object of the methodology is the study of the problem in situ, in order to carry out laboratory tests that allow to select the concentration, pH and the most appropriate application method and finally to go back to the building to test the treatment in pilot areas, which permits to guarantee the success in the application of salt crystallisation inhibitors inside stony materials, as we have proved in San Jeronimo.

The research work is part of the SALTCONTROL project, financed by the 6th framework Programme of the EU for the period 2004-2007. Together with the University of Granada, other organisms have participated in the project: the University of Muenster (Germany), the University of Gant (Belgium), the University College of London, the University of Patras in Greece, the Technical University of Prague, the Architecture Conservation Centre TNO of Holland, the Andalusian Institute of National Heritage and the Technical University of Eindhoven.

SALTCONTROLs results have been successfully applied in the Monastery of San Jeronimo (Granada-Spain) and the Fortress of Teresina (Prague, Czech Republic).
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– Scientists prove the geochemical origin of part of the CO2 emissions in semiarid climates

The implementation of the Kyoto Protocol has raised, among other pressing matters, the need of getting to know the annual levels of carbon in different earths ecosystems. Scientists connected with the CEAMA-Andalusian Centre for the Environment (University of Granada-Andalusian Council) are studying these levels in semiarid Mediterranean scrubland, situated in Eastern Andalusia, whose results are comparable to wide regions of the world.

These researchers have analysed for the first time the CO2 level in carbonated semiarid systems. The interest of the work lies in the knowledge of the CO2 production processes and their absorption and in the conservation of one of the richest ecosystems of Spain.

One of the most recent studied on the subject is the doctoral thesis CO2 interchanges between atmosphere and Karst ecosystems: Applicability of the commonly applied techniques, read by Penelope Serrano Ortiz and led by Doctors Andrew S. Kowalski and Lucas Alados Arboledas.

The work, supported by the Carbon and water balance in Mediterranean thicket ecosystems in Andalusia: Effect of the climatic change project, has permitted to quantify and identify the processes involved in carbon annual balance in a semiarid carbonated substrate ecosystem, situated in Sierra de Gador (Almeria). After three years of observation of this ecosystem (2004-2006), through the use of the most advanced techniques (attached photo), have permitted to estimate the annual carbon balance. The carbon balance of this type of ecosystem has been checked for the first time, revealing that it acts as a CO2 drain which assimilates approximately 25 g C m-2 a year (between 10 and 20 times lower than arable land and tree ecosystems respectively).

What is the meaning of this in an area characterised by a scrubland vegetation and a dry climate? Up to now, when it came to devise measures to prevent climatic change, they used to value tree ecosystems especially; that is the origin of the emphasis made in the reforestation and forestation of neglected agricultural land. But little attention had been paid to other ecosystems, such as the thicket ecosystem object of this study, which represents more than half the forest area of Andalusia (where a great part of the biological diversity of the Mediterranean ecosystems gathers together).

In that respect, besides defining the CO2 assimilation capacity of the studied thicket area, Serranos thesis has proved how rain distribution conditions the functional nature of the studied ecosystem and how the duration of the drought period and, therefore, the water content, determinates the duration of the CO2 geochemical emissions, through soil ventilation.

It proves that CO2 production is not only related to vegetation, but also to geochemical emissions which increase in dry seasons.

The hypothesis formulated in this work – says Serrano – is that the emissions are a consequence of a ventilation phenomenon of the carbonated systems macro-pores, which appear to be connected with wind speed. In this line, certain studies on degasification phenomenon in caves and turbulent CO2 interchanges with the atmosphere, carried out by Sergio Sanchez Moral and Soledad Cuezva Robleno (Spanish Museum of Natural Sciences, CSIC) in the Altamira Cave, endorse the theory of the existence of CO2 geochemical flows in ecosystems situated in karst substrate.

CO2 is one of the main greenhouse gases which contributes to the rise of earths temperature. Serrano Ortizs study is the first one focused on carbonated semiarid ecosystems and has proved that they act as CO2 drains, due to the action of the thickets, and as CO2 geochemical generators in dry periods (especially worrying if we reach the temperature rise predicted by climatic change models).

His work provides data of C (carbon) flows in key ecosystems for biodiversity conservation, as well as for the negotiations related to CO2 emissions.
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– Researchers compiled 20th century temperature data in Spain as evidence of climatic change

This research work is the first step to confirm the existence of a temperature change. Their main goal has been to detect the signs of the Climatic Change through the temperatures in Spain, explained to SINC the researcher of the department of Applied Physics of the University of Granada and main author, Matthias Staudt.

The compilation of maximum and minimum temperature series of every month since the end of the 19th century until the beginning of the 21st century has not always been an easy task. The data, which have been collected in 45 Spanish observatories, were not homogeneous in every case. In climatology, a series of data (temporary series) is considered as homogeneous when its content reflects exclusively the climatic evolution (this is, when the different indexed factors are absent). Therefore, the researchers work has mainly consisted in removing inhomogeneous pollution in data.

According to the scientist, analysing the quality of the data – which were published in November in the International Journal of Climatology – becomes, the best method to believe in the final results. Technical preparation is essential to take the second step and do research into the rise of temperature at an unquestionable statistical level, he added.

Changing a thermometer which has been calibrated in a different way is one of the factors why temperature data usually present incoherencies. In addition, the different reading interpretations of a human being or the frequent location changes of the observatories (changes from a urban environment to an airport, altitude changes, etc.) are problems with which the scientific team has had to deal with.

Moving a thermometer without recording this fact gives rise to a very strange result which can not be explained 50 years later, explained Staudt. Besides this, there are human typographical errors which present non-homogeneous data.

Scientists have been working for five years to find out, evaluate and repair the data series. In order to make them as reliable as possible without converting them into a pretext for those reluctant to admit the existence of the Climatic Change, explained the researcher. Although he admits that he has not obtained absolute conclusions, he has managed to establish a normality criterion in the behaviour of temperatures. With a high level of probability, a qualitative decrease of seven degrees from April to May is not normal, as there should be a rise in any case, he said.

Due to the homogeneisation problems specified in the analysed monthly series, the researchers have set themselves a very strict detection of un-homogeneities criterion. Despite this, the instrumental error in a temperature measurement is in the order of 0.1 C, and the error of a difference between data, previously treated with the homogeneisation method, rises to the order of 0.4 C. This error is not negligible but anyway it is considerably smaller than the gross data.

To come to conclusions that confirm climatic change in Spain, at a high level of reliability, this technical work involves a necessary and obvious effort. Staudt said that the results obtained about the Climatic Change are not new, but they will confirm what we (almost) already knew.
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