Biodeterioration and Conservation Status of Marble Monuments on Crimea

Biodeterioration and conservation status of marble monuments on Crimea

W. Krumbein*, E. Bogomolova^, A. Gorbushina', L. Parana', O. Rybalchenko', S. Ryshov\ E. Sagulenko', D. Vlasov'

"Car/ von Ossietzky University of Oldenburg, P.O. Box 2503 D- 26111, Oldenburg, Germany

^Chersonesus Musuem-preserve, Sevastopol 335045, Crimea ^St. Petersburg State University, Universitetskaya emb. 7/9, St

Petersburg 199034, Russia

Introduction

The investigations of biodeterioration and conservation of stone monuments in the Mediterranean basin are concentrated mainly in the last decades in the countries and sites on the Mediterranean itself /Anagnostidis et al. 1992 ; Diakumaku et al. 1994; Krumbein , Urzi,1992,1993;Urzi et al.1992,1993,1994/.

Crimean ancient Greek colonies - a periphery of antique world are, nevertheless, the integral part of the culture of that period /Minns,1913; Reinach,lS97; Sokolov,1973/. The first Hellenic colonies on the Northern coast of the Black sea were founded in YII- YI B.C. In the words of the famous orator Cicero,they were like a border sewn on the vast expanse of barbarian lands. Stretching along the coast, they never penetrated far inland. The territory of Western and Southern Crimea, adjacent to the sea, belonged to the Chersonesus State. The town Chersonesus of the Tauride (422-421 B.C.),(Greek for peninsula) that was the last Hellenic colony in Crimea, and also earlier settlments : Kalos Limen (IY B.C.) and Kerkinitida (YI B.C.) were the centres of Chersonesus country. The Eastern coast of Crimea was the part of Bosporian Kingdom, which united ancient cities on both sides of contemporary Kerch strait. These settlements appeared in YI B.C. as independent and then, in 480 B.C. they united. Pantykapea was the centre of antique Bosporian Kingdom and situated on low-lying terraces, on slopes and the top of mountain Mythridad, (now Kerch). Fig. 1.

Archeological excavations on Crimea have been carrying out since last century. Investigations and creation of detailed appearance of most of the antique towns are impeded by contemporary buildings.

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Chersonesus of the Tauride , which outlived Hellenistic, Roman and Bysantine epoches and was ruined in 1287 by tartars , is the exception . Now there is a large archeological museum-preservation on it's territory,where even today anyone can stroll along the ancient streets, visit the antique theatre, admire the polychrome mosaics floors in temples decorated with marble relief compositions, colomns. Figs. 2,3.

The most valuable exhibits, which were discovered

in the antique settlements and in necropolises on Crimea, are kept now in museum' collections of Russia and Ukraine. Other monuments are awaiting for their discovery. The aim of our work was to investigate conservation status with special respect to biodeterioration , of marble and limestone monuments being exposed outdoors in archeological sites in Crimea in comparison with monuments of Mediterranean countries. The two directions of scientific investigations were followed:

(1) Field experiments: - macroscopic observations in situ of signs of deterioration, classified as biological attack ; sampling; estimation of effectivity of protective treatments,that have been already used to the moment; (2) Lab experiments: - recognition and identification of marble infected by black fungi; isolation and identification of black fungi destroyed marble ; studying of some physiological characteristics of isolated strains in pure cultures; modelling experiments on marble slabs.

Materials and methods

Sampling Field investigations and collecting of samples were carried out during the period of autumn-spring- summer seasons of 1993 - 1994. Altogether three expeditions took place, one of which consisted of scientists from Russia, Germany, Ukraine. We carried out macroscopic visual observations and documented photographically signs of biodeterioration and alteration of stone monuments during the field investigations. The remains of buildings in settlement,the ruins of marble basilics of Y, YI, YII centuries, medieval polychrome mosaics, marble columns and sculptures in the museum garden were investigated in Chersonesus. Some of marble sarcophagus and stelaes, exhibiting

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outdoors and under the roof were the objects of our studies in Kerch and Feodosia. Also the ruins of

former settlements around Pantykapea, such as Myrmeky, Tiritaki, Nymphea were investigated.

Marble and limestone According to historico - archeological data , Crimean limestone and marble imported from island Prooonnessus were used for creating monuments and buildings in antique Crimea.

As the result of microbiological analysis, some bacteria, algae, lichens and also fungi, especially black fungi that are considered to be the main agents of marble destruction, were discovered on Crimean Monuments made of marble and limestone. For isolation of fungi some replies on stick TESA films and agar- print technique were used from the surface of stone monuments as nondestructive methods. In lab the isolation of fun^i from pieces of damaged marble was conducted with the help of sterilized injeotional needle and binocular microscope. The identification of black fungi was carried out by reference books of Ellis, 1993. Different physiological tests of fungi were conducted such as acid production ( Krumbein, 1992; Krumbein et al. 1993) , ESR - speotroscopy studies of melanins synthesis ( Gorbushina et al. 1993, Soukharjevsky et al.1994), resistance to heavy and transition metals ( Mamonova et al. 1992 ) and utilization of different carbon and nitrogen sources . The methods of batch cultures , including cultivating on marble slabs, on Petry dishes and in flat- bottom microtiter plates were used.

Experimental methods The fluorescence and optic microscopy, SEM/ TEM analys i s, transmi tt i ng and reflect i on photometry Tv- image analysis, ESR spectroscopy were used.

Results and discussion Macroscopic observation of principal destruction patterns showed agress i ve i nfl uence of both environmental and microbiological factors that is typical for Mediterranean countries (Krumbein et al" 1992, 1993; Urzi et al. 1992, 1994; Zezza ,1994). The main decay factors of environment are : marine spray, atmosphere sulphatic agress ion and other technogenic pollution in industrial cities (Sevastopol, Kerch) , seasonal cycles of freezing - melting, alternating

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repeatedly during the day; strong autumn winds and flooding of some remains owing to rising of sea level over 5 meters since antique tine.

As for biodeterioration patterns, on the surface of marble, that has been exposed outdoors for a long time, the associations of fungi, lichens and algae are forming. The depth of fungal penetration into marble depends much on structure and composition of substratum, and also on it's age and time of exposition outdoors. On many samples it reached 5-8 mm. At the same time cracks that are parallel the surface, are often filled with green-blue algae, that can find there necessary moisture and protection from surplus sun light. It should be noted that the chemical treatments such as fungicides, consolidants (KO-9, KO-15 ), hydrophobic films ( Wacker H, 290A) used for protection of marble monuments during past decades in Chersonesus were effective only in the time period 0.5- 1 year. As the typical signs of deterioration of marble by fungi the presence on it's surface of hyphal structures and microcolonies (Staley et al. 1982) , sometimes stretching into substratum, can be mentioned. Fig. 4. The crust, consisting of different structures of fungi and others microorganisms and also of deposits of minerals having biological origin was discovered on many samples of antique marble. We observed limestone ruins in Pantykapea, covered with 5-10 mm layer of deposits on which the boundaries of thailorn of endolythic lichens could be clearly seen. On the fragments of monuments that were excavated at different years, the obvious boundaries of sections can be seen. They evidence about more favourable conditions for exhibits conservation, especially mosaics, under the ground as was early pointed by Saiz-Himenez et al. 1991.

Marble samples is characterized by structural heterogeneity, the maximums in distribution of pores that were determined by the method of mercury intrusive porometry are at 0.3-lmkm and 5-7mkm , Kumzerov et al. 1994.

We managed to isolate more than 60 strains of hyphomycetes from the surface of damaged Proconessus marble. They belong to different taxonomic groups. Among them there are widespread soil fungi from genera Alternaria, Botrytis, Hyphoderma,Cladosporium, Penicilium, Aspergillus, Phoma, Pestalotia, Fusarium.

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Nearly half of all the isolated strains had no speculation or formed only chlamidospores in the conditions of pure cultures. All investigated micromycetes had pigmentation, and nearly 90% of strains were dark colored and contained"melanins in the cell walls concern TEM and ESR analysis

me most interesting are the fungi that r.an be classified as black yeasts *De Hoog et al. 1977) causing intensive colour changing and slowly "hut persistently like stealth viruses destroying of materials .Fig.5. Yeast - like melanin containing fungi can be probably considered as the constant inhabitants of stone surface. Thev are well adapted LO the existence on such mineral substratum as marble and have approximately 100 times highest the minimal inhibiting concentrations to metal ions <,han museum cultures.

t he fung i i nhab i t i ng mar bl e and

oiodeteri oration status of Crimean monuments we investigated were compared to those previously studied in the western Mediterranean Basin . As a summary a general line of biological attack

The present status of this work is in beginning so we are intend to focus our future reseach on the mechanisms involved in black fungi and minerals interaction in order to develop and apply effective technologies for the conservation and restoration nf mar b 1 e monume nts.

^ Tt,T support by VW-Stiftung, grant 1/68 491 and of INTAS , grant INTAS - 93 - 1059, is gratefully acknowledged.

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Fig. 1 The position of the former Hellenic colonies on Crimea: 1 - Chersonesus of the Tauride, 2 - Pantykapea

Fig.2 Chersonesus of the Tauride.View on the temples "Basilica in basilica"

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Fig. 3 Medieval polychrome mosaic from Crimea.

Fig.4 Fragment of the surface of ancient marble monument damaged by yeast-like black fungi.

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Fig.5 Black fungi strain Ch56 isolated from marble column.