695

STUDIES OF BIODETERIORA TION OF BUILDING MATERIALS ON BONSOR CASTLE (SEVILLE, SPAIN)

SAMENO PUERTO, MARTA

lnstituto Andaluz del Patrimonio Hist6rico, Isla de la Cartuja, 1, 41071 Sevilla (Spain)

GARCIA ROWE, JORGE

Vegelal Biology and Ecoklgy Dept. Fae. of Pharmacy, Cl Prof. Garcia Gonzalez sin 41012 Sevilla (Spain)

VILLEGAS SANCHEZ, ROSARIO

lnstituto Andaluz del Patrimonio Hist6rico, Isla de la Cartuja, 1, 41071 Sevilla (Spain)

SUMMARY

In this work the flora existing on Bonsor Castle has been identified, both vascular and non vascular plants. To identify lichens visual examination, optical and electronical microscopy and specific reactives have been used. Several biocides treatments have been tried, to evaluate their efficacy on adobe and stone, on algae and lichens. Their behaviour has been measured by means of visual examination, optical and electronical microscopy.

1. INTRODUCTION

The first architectonic structures that remain in the Castle of Mairena del Alcor (also called Bonsor Castle) could be dated around 1342. The four towers and the walls which join them are still visible. The entrance would be possibly in the North side. Around 1470 the castle are transformed by adding a fosse and a external wall with loopholes. Biodeterioration that suffer stone materials from buildings, archaeological sites and sculptures is increasing (0. Allsop et al. 1986 ). One of the most important causes is the action of plants, both vascular and no vascular (G. Caneva et al. 1993). With respect to the environmental conditions, two kinds of bioweathering could be distinguished: when humidity of substrate is continuous, cyanobacteria, algae and bryophytes are predominant (G. Caneva et al, 1994); if humidity is not permanent, lichens of crustoise biotype, which increment substrate alteration, are present. Lichens could cause chemical and mechanical damages to the substrate (Griffin et al, 1991). The presence of lichens - foliose or crustoise, and ephilitic or endolitic - appears in the forms of fragments and dust (ICR-CNR, 1985). They are organisms of slow growing with little ecological needs and very resistant to extreme temperature and humidity conditions. Lichens have a very wide distribution, influenced by environmental conditions and the distribution of nutrients and minerals: saline deposits, excrements of pigeons (high contents of phosphorous and nitrogen). Over limestone, the predominant biotype is crustoise, although there are also some foliose and escuamuloise

biotypes. Another factor of weathering are vascular plants, that can provoke physical and mechanical damages as well

as chemical ones. Birds are also an important deteriorating agent, being related to the growing of omithocoprophilous plants. So the analysis and characterization of vegetation must be considered an important previous contribution to

the study of biocide treatments for conservation of building (Schnabel, 1991).

2. MATERIAL AND METHOD

2.1. Localization The castle is located on Los Alcores, a geological formation situated beneath two areas: quaternary terraces of Guadalquivir and La Vega. It is situated at the edge of the Alcor, and surrounded on the Northeast by the town

of Mairena del Alcor. The main entrance is oriented to Southwest.

696

2.2. Substrate The castle is built mainly with a sedimentary rock, a biocalcarenite, and adobe. There are also lime mortar, brick and cement. The stone is a limestone of organic origin formed by accumulation of sediments constituted mainly by calcareous rests of marine organisms. This origin determines a high porosity, which makes the stone easily attackable by atmospheric agents, and colonizable by organisms. Some samples of biocalcarenite covered by lichens, specially Lecanora muralis, have been analyzed by X-Ray diffraction, to detect changes on the mineralogical composition of stone.

2.3. Analysis and determination of species Biological weathering of stone monuments could be evaluated through the analysis and determination of organisms present. So, morphologic, microbiologic, biochemical, histochemical and chemical methods could be used. Morphologic and structural methods need several techniques of examination of stone material (ICR-CNR 1987): - visual examination - stereomicroscopy, allows to identify the organisms that are present - optical microscopy, it is used to recognise the morphology and cellular structure of each group of organisms and microorganisms - SEM, for tridimensional observation of cells or stone surface.

For lichens, samples were taken carrying out inventories on areas of different ecology. The characteristics of each area, kind of substrate, orientation, inclination, were registered, as well as the species that appear, together with two index: abundance/dominance and sociability. The fertility of each taxon in each area is also indicated. So, all data useful to determine and describe each taxon on each ecology are compiled. The determination and description have been carried out in the laboratory, using stereomicroscope and optical microscope, following Ozenda et al 1970. Besides the observation of thalli morphology and sexual reproduction structures (mainly apothecia), some genders needed chemical tests to be identified, by using the following reactives: - Concentrated solution of KOH in water - Commercial aqueous solution of NaCIO (concentrated bleach) - Iodine solution on Kl - Concentrated nitric acid

For certain species it was necessary to observe the morphology of spores, making a fine cut on the reproductive structure and observing with microscope. So, information about spores and their characteristics -contour, presence or absence of partitions, size, etc - is obtained. For what refers to vascular plants, a vegetation typical of nitrofile, arid, sunny places, like road borders, building sites, etc, is found. Samples have been taken on different phases along the seasons. For the determination and description the following bibliography has been used: G. Bonnier and G. de Layens (1988), B. Valdes, S. Talavera and E. Fernandez-Galiano (eds.) (1987); O. Polunin (1977).The results have been confirmed by specialist from the Vegetal Biology and Ecology Department (University of Seville).

2.4. Evaluation of the efficacy of biocide treatments The selection of biocide treatments was carried out taken into account the organisms that appear on the monument. These products were chosen among those more frequently used for stone monuments conservation. Their behaviour through time was studied.

The treatments used are: benzalconium chloride, formaldehyde, sodium hypochlorite and hydrogen peroxide. They were dissolved on distilled water in a concentration that could reproduce the effect of repeated treatments (seasonal treatments) (Nugari et al 1993). These biocides were tested in situ by application on the substrate (stone and adobe) with brush, and in the laboratory applying them by immersion of the surface of the samples on the solution during 5 minutes.

The efficacy of the treatments was evaluated studying directly the organisms on different periods of time and with the optical microscope and SEM (ICR-CNR 1981).

697

2.5. Scanning electron microscopy

Samples were fixed in a solution of 1% glutaraldehyde in 0.01 M phosphate buffer. After subsequent fixing in osmium tetroxide (1%), samples were dehydrated in a graded series of ethanol (30-70%), submerged in

acetone (70-100%), dried in a critical point drier and gold coated (X. Arii'lo et al., 1995). A Philips XL 20 microscope operating at 10 kv was used.

3. RESULTS AND DISCUSSION

3.1. Determination of species

The species that are present in the Castle appear on Tables 1 and 2. Among the lichens, the most abundant

biotype is crustoise, followed by escuamuloise and foliose. Wrth respect to species, there are great differences due to the substrate and orientation.

Table 1

Lichens from Bonsor Castle

SPECIES

Acarospora isolata H. Magn. Aspicila coronata (Massal.) B. de Lesd. Ca/oplaca ca/lopisma (Ach.) Th. Fr. Caloplaca citrina (Hoffm.) Th. Fr. Ca/oplaca dolomiticola (Hue) Zahlbr. Ca/oplaca oasis (Massa!.) Szat. Caloplaca teicholyta (Ach.) Steiner Ca/oplaca variabilis (Pers.) MOii. Arg Candelaria concolor Massal. Candelariella aureHa (Hoffm.) Zahlbr. Candelariella vitellina (Eh rt.) MOii. Arg. Collema cristatum (L.) G. H. Web. Collema sp. Oermatocarpon trapeziforme (Koenig) Trevis. Endocarpon cf adsendens (Anzi) MOii. Arg. Endocarpon cf pusillum Hedw. Lecania erysibe (Ach.) Mudd. Lecania spadicea (Flot.) Zahlbr. Lecanora albescens (Hoffm.) Floerke. Lecanora crenulata (Dicks.) Hook. Lecanora dispersa (Pers.) Rohl. Lecanora mura/is (Schreb.) Rabenh. Uchinella stipatula Nyl. Lepraria aeruginosa (Wigg.) Sm. Physda grisea (Lamk.) Lett. Pladdiopsis custanii (Massa I.) Koerb. Psora crenata (Tayl.) Reinke Rinodina sa/ina Degel. Verrucaria hiascens (Ach.) Hepp. Verrucaria tabacina (Massal.) Trev. Xantoria aureola (Ach.) Erichs.

BIOTYPE

Escuamuloise Crustoise Crustoise Crustoise Crustoise Crustoise Crustoise Crustoise

Folioise Crustoise Crustoise

Folioise Folioise

Escuamuloise Escuamuloise Escuamuloise

Crustoise Crustoise Crustoise Crustoise Crustoise Crustoise Crustoise

Leprarioise Folioise

Escuamuloise Escuamuloise

Crustoise Crustoise Crustoise

Folioise

Table 2

Vascular Plants from Bonsor Castle

SPECIES

Amygda/us communis L. Aptenia cordiffora (L. fil.) Schwantes Avena sterilis L. Bromus maximus Dest. Bromus sterilis L. Calendula arvensis L. Chenopodium album L. Conyza canadensis (L.) Cronq. Diplotaxis muralis (L.) DC. Dittrichia viscosa (L.) Greuter Erodium malacoides (L.) L'Her Erodium moschatum (L.) L'Her Euphorbia helioscopia L. Euphorbia lagascae Sprengel Euphorbia pep/is L. Reus carica L. Fumaria bastardii Boreau in Duchartre Fumaria parviffora Lam. Hordeum maritimum Stokes Hordeum murinum L. Koeleria phleoides (Viii.) Pers. Lamarckia aurea (L.) Moench Unumsp. Malva hispanica L. Melilotus sulcata Dest. Mercuria/is annua L. Mesembryanthemum nodifforum L. Micromeria graeca (L.) Bentham ex Reichenb. Misopates orontium (L.) Rafin. Muscari racemosum Mill. Oxa/is pes-caprae L. Papaver dubium L. Parietaria lusitanica L. Parietaria mauritanica Durieu Paronychia argentea Lam. Phagna/on saxatile (L.) Cass. Piptatherum mtliaceum L. Plantago afra L. Plantago /agopus L. Plantago major L. Poa annua L. Reichardia intermedia (Schultz Bip.) Samp Rosmarinus officina#s L. Senecio vulgaris L. Silene sp. Spergu/a sp. Sonchus oleraceus L. Stellaria media (L.) Viii. Stipa tortilis Dest. Sysimbrium irio L. Umbilicus pendulinus DC. Urospermum picroides (L.) Scop. Urtica dioica L. Urtica dubia Forskal Urtica ureus Forskal Verbena supina L. Veronica hederifo/ia L. Vinca difformis Pourret

698

BIO TYPE

Phanerophyte Chamaephyte

Therophyte Therophyte Therophyte Therophyte Therophyte Therophyte Therophyte Therophyte Therophyte

Hemicriptophyte Therophyte Therophyte Therophyte

Phanerophyte Therophyte Therophyte Therophyte Therophyte Therophyte Therophyte Therophyte Therophyte Therophyte Therophyte

Chamaephyte Chamaephyte

Therophyte Cript6fito

Therophyte Therophyte Therophyte Therophyte Therophyte

Hemicriptophyte Hemicriptophyte

Therophyte Hemicriptophyte

Therophyte Therophyte Therophyte

Chamaephyte Therophyte Therophyte Therophyte Therophyte Therophyte Therophyte Therophyte Therophyte Therophyte Therophyte Therophyte Therophyte Therophyte Therophyte

Hemicriptophyte

699

The interphase between biocalcarenite and Lecanora muralis has been analyzed by X-Ray diffraction, with the results that can be observed on figure 1 ; the quantity on calcite decreases while there is a high concentration of calcium oxalate (whewellite).

Superior plants correspond to a vegetation typical of dry, sunny places. The most abundant families are ASTERACEAE, POACEAE, BRASSICACEAE and URTICACEAE, and also some GERANIACEAE. The biotypes present are mainly therophyte followed by hemicriptophyte. Chamaephytes (bushes) are important too, although in lesser proportion, as well as criptophytes (bulbous plants).

3.3. Efficacy of biocides treatments Firstly, the behaviour of treatments has been studied in situ. The observations have been carried out just after the application, a week later and two months later. The products have been applied over two kinds of substrate for lichens, stone and adobe, and adobe for algae (Figures 2 and 3). Among all the products, benzalconium chloride and hydrogen peroxide seem to be the most effective. Through the observation with optical microscope and SEM this result has been confirmed. Or algae and

lichens treated with both products, the cells are collapsed, and on the interphase between lichen and stone, the hyphae are covered with a kind of dust or granules (Figures 4 to 7).

4. CONCLUSIONS

The analysis and determination of the flora and vegetation that grows on the castle must be considered as a previous step to the evaluation of biocide treatments with the aim of conservation. Biodeterioration of stone is a very much slow process than physical or chemical weathering, for what some times elimination of organisms present over the stone could be prejudicial, since they retard erosion due to atmospheric agents. It has been observed that those blocks that do not have the protector cover of lichens have a high degree of deterioration that those ones which are completely o partially colonized. The treatments more effective have been benzalconium chloride and hydrogen peroxide, fact that has been

confirmed with different techniques of observation.

REFERENCES

ALLSOPP, D. & KJ. SEAL (1986). Introduction to biodeterioration. Edward Arnold, London. ANDRADA J. & A FRANCO ( 1975). Sobre el area de invernada de Falco naumanni en Espana. Ardeola, 21

(especial), 321-324. ARINO, X, J. J. ORTEGA-CALVO, A G6MEZ-BOLEA & C. SAIZ-JIMENEZ (1995). Lichen colonization of the Roman

pavement at Baelo Claudia (Cadiz, Spain): biodeterioration vs. bioprotection. Sci. Total Environment, 167, 353-

363.

BONNIER, G. & G. DE LA YENS (1988). Claves para la determinaci6n de plantas vasculares. Ediciones Omega. CANEVA G., G. DE MARCO & MA PONTRANDOLFI (1993). Plant communities on the walls of Venosa castle

(Basilicata, Italy) as biodeteriogens and bioindicators. Conservation of stone and other materials: Vol. 1, 263-

270. (M.J.Thiel). Rilem, London. CANEVA G. , M. P. NUGARI & 0. SALVADOR! (1994). La biologia nel Restauro. Nardini, Firenze. GARCIA ROWE, J. & C. SAIZ JIMENEZ (1991 ). Colonizaci6n y alteraci6n de la piedra por lfquenes, briofitos y plantas

superiores en las catedrales de Salamanca, Sevilla y Toledo. Jomadas sobre restauraci6n y conservaci6n de monumentos (1989-Madrid). Ministerio de Cultura. Direcci6n General de Bellas Artes Y Archives. Institute de

Conservaci6n y Restauraci6n de Bienes Culturales, pp. 71-79. GARCIA ROWE, J. & c. SAIZ JIMENEZ (1991 ). Lichens and bryophites as agents of deterioration of building materials in

Spanish Cathedrals. International Biodeterioration: Vol. 28, 151-163. Biodeterioration of Cultural Property (Ed.

Robert J. Koestler). Elsevier, London and New York. GRIFFIN, P. S., N. INDICT OR & R.J. KOESTLER ( 1991 ). The biodeterioration of stone: a review of deterioration

mechanisms, conservation case histories and treatment. International Biodeterioration: Vol. 28, 187-207.

Biodeterioration of Cultural Property (Ed. Robert J. Koestler). Elsevier, London and New York.

700

ICR-CNR (1981 ). Esame delle caratteristiche morfologiche al microscopio elettronico a scansione (SEM). Normal 8/81 .

ICR-CNR (1985). Microflora autotrofa ed eterotrofa: tecniche di indagine visiva. Normal 19/85.

ICR-CNR (1987).Metodologia di rilevamento e di analisi della vegetazione. Normal 24/86.

NUGARI, M.P., P. PALLECHI & D. PINNA (1993). Metodological evaluation of biocidal interference with stone materials-

Preliminary laboratory tests. Conservation of stone and other materials: Vol. 1, 205-212. (M.J.Thiel). Rilem,

London.

OZENDA, P. & G. CLAUZADE (1970). Les lichens. Etude biologique et ftore illustree. Masson et Cie, Paris. POLUNIN, 0 . (1977). Gura de campo de las ftores de Europa. Ed. Omega.

SCHNABEL, L. ( 1991 ). The treatment of biological growths on stone: A conservator's viewpoint. International

Biodeterioration: Vol. 28, 125-131. Biodeterioration of Cultural Property (Ed. Robert J. Koestler). Elsevier,

London and New York.

SEAWARD M. D. & C. GIACOBINI (1988). Lichen-induced biodeterioration of italian monuments, frescoes and other

archaeological materials. Lichens and monuments. C.N.R. Centro di studio. "Cause di deperimento e metodi di

conservazione delle opere d'arte".- Roma. P. L. Nimis & M. Monte, Trieste.

V ALD~S. B., S. TALAVERA & E. FERNANDEZ-GALIANO (eds.) ( 1987). Flora vascular de Andalucfa occidental. Ketres, Barcelona.

FIGURES

c a

Wh Wh

II I I I

10

Figure 1. X-Ray Diffraction of interface between biocalcarenite and Lecanor.·n z· Q artz C al ·te F hil m· u mura is. qu , c c1 , p os cate, Wh whewellite .

701

Figure 2 . Preapplication Figure 3. One week after application Biocide treatments applied on algae growing over adobe

Figure 4. Hyphal network penetrating the biocalcarenite

Figure 5. Interface between biocalcarenite and Lecanora muralis, treated with distilled water

Figure 6 . As 5 treated with henzalconium Figure 7. As 5 treated with hydrogen peroxide

chloride