Analytical Protocol for the Scientific Investigation of Black Crusts on the Exterior Finish of the West Enclosure Wall of Golia Monastery (Iași, Romania): A Case Study on Urban Pollution Impact
Source abstract
Abstract
Black crusts are multilayered alteration products that develop on historic masonry exposed to urban pollution. This study investigates the west enclosure wall of the XVIIth-century Golia Monastery in Iași, Romania—located along a busy traffic corridor—and presents multi-analytical results on two lime-based mortar fragments exhibiting well-developed blackened surface layers. Both the exposed (blackened) finishes and protected verso areas were analyzed using portable X-ray fluorescence (pXRF), scanning electron microscopy with energy-dispersive X-ray analysis (SEM–EDX), micro-FTIR spectroscopy, X-ray diffraction (XRD), CIE Lab colorimetry and optical microscopy (OM). The data reveal gypsum-rich surface layers enriched in traffic-derived particles, including metal oxides and soot, with marked contrasts relative to the minimally altered verso. Handheld XRF and SEM–EDX indicate elevated sulfur and associated traffic-related elements within porous gypsum matrices, while FTIR and XRD consistently identify calcium sulfate as the dominant secondary phase. Colorimetric measurements additionally document pronounced lightness loss and visible darkening on exposed surfaces. These results demonstrate the onset of directional sulfation and black crust formation on mortars under urban pollution pressure and establish an integrated analytical protocol for diagnosing black crusts on historic lime mortars in urban heritage settings.
Source: crossref · Quality: baseline
Research context
OpenAlex topics: Building materials and conservation · Cultural Heritage Materials Analysis · Conservation Techniques and Studies
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
Affiliations
Laboratory of Applied Meteorology and Climatology, Research Center with Integrated Techniques for Atmospheric Aerosol Investigation in Romania—RECENT AIR Department of Exact Sciences and Natural Sciences, The Institute of Interdisciplinary Research, Alexandru Ioan Cuza University of Iași, A Building, Physics, 11 Carol I Bld., 700506 Iași, Romania
Atmosphere Optics, Spectroscopy and Laser Laboratory LOASL, Faculty of Physics, Alexandru Ioan Cuza University of Iași, 11 Carol I Bld., 700506 Iași, Romania
ARHEOINVEST Center, Department of Exact Sciences and Natural Sciences, The Institute for Interdisciplinary Research, Alexandru Ioan Cuza University of Iaşi, Carol I Boulevard, no. 11, 700506 Iași, Romania
Center of Advanced Research in Bionanoconjugates and Biopolymers, Petru Poni Institute of Macromolecular Chemistry, 41A Grigore Ghica Voda Alley, 700487 Iași, Romania
Faculty of Physics, Alexandru Ioan Cuza University of Iași, 11 Carol I Bld., 700506 Iași, Romania
Institute of Archaeology, Romanian Academy, Iași Branch, 6 Codrescu St., Pavilion H, 700479 Iași, Romania
Academy of Romanian Scientists AOSR, 54 Splaiul Independentei St., Sector 5, 050094 Bucharest, Romania
National Institute for Research and Development in Environmental Protection, 294 Splaiul Independentei St., Sector 6, 060031 Bucharest, Romania
Romanian Inventors Forum, Sf. Petru Movila St., L11, 3-3, 700089 Iași, Romania
References (69)
Show source-provided references
1. Characterization of Black Crusts Developed on Historic Stones with Diverse Mineralogy under Different Air Quality Environments10.1007/s11356-021-15514-w ↗
2. Marszałek, M., Dudek, K., and Gaweł, A. (2024). Black Crust from Historic Buildings as a Natural Indicator of Urban Environmental Contamination: A Case Study of the Lipowiec Castle in Southern Poland. Sustainability, 16.10.3390/su16093816 ↗
3. The Historic Built Environment as a Long-Term Geochemical Archive: Telling the Time on the Urban “Pollution Clock”10.1021/acs.est.3c00153 ↗
4. Black rusts as pollution indicators
5. Colorimetry to Assess the Visual Impact of Dust Deposition on Mosaics at Sheltered Archaeological Sites10.1186/s40494-021-00509-0 ↗
6. Postolachi, C., Cocean, A., Garofalide, S., Munteanu, B.S., Cocean, G., Cimpoesu, N., Pelin, V., Cocean, I., and Gurlui, S. (2023). Urban Exotic Pollution: The Harmful Environmental Footprint for Health and Historical Architecture. Int. J. Environ. Res. Public Health, 20.10.3390/ijerph20064715 ↗
7. Physico-chemical Adhesion and Cohesion Bonds in Joint Mortars Imparting Durability to the Historic Structures10.1016/S0950-0618(99)00045-8 ↗
8. Mortars and Plasters—How to Manage Their Conservation10.1007/s12520-021-01409-x ↗
9. Evaluation of Mortar Mix Designs for the Conservation of the Acropolis Monuments10.1016/j.culher.2022.04.004 ↗
10. A Multi-Analytical Approach for the Characterization of Black Crusts on the Façade of an Historical Cathedral10.1016/j.microc.2020.105121 ↗
11. Marble Chromatic Alteration Study Using Non-Invasive Analytical Techniques and Evaluation of the Most Suitable Cleaning Treatment: The Case of a Bust Representing Queen Margherita di Savoia at the U.S. Embassy in Rome10.3390/analytica3040028 ↗
12. Colorimetry Applied to the Field of Cultural Heritage: Examples of Study Cases
13. Siegesmund, S., and Middendorf, B. (2020). Conservation state assessment of the Golia Monastery enclosure wall. Monument Future: Decay and Conservation of Stone, Proceedings of the 14th International Congress on the Deterioration and Conservation of Stone (STONE 2020), Mitteldeutscher Verlag.
14. Black Crust versus Substrate on Historic Stone: A Brief pXR Study at Golia Monastery (Iași, Romania)10.36868/IJCS.2025.04.25 ↗
15. Modern Aspects Regarding the Conservation of Cultural Heritage Artifacts
16. New Interdisciplinary Aspects on Science for Conservation of Cultural heritage (II)
17. Current Studies and Approaches in the Field of Cultural Heritage Conservation Science: Harmonizing the Terminology in an Interdisciplinary Context
18. Sandu, I. (2023). New Materials and Advanced Procedures of Conservation Ancient Artifacts. Appl. Sci., 13.10.3390/app13148387 ↗
19. Materials for Finishing of Ancient Monuments and Process of Obtaining and Applying
20. (2026, January 20). Available online: https://www.crystalimpact.de/match/.
21. Color difference Delta E—A survey
22. The CIEDE2000 Color-Difference Formula: Implementation Notes, Supplementary Test Data, and Mathematical Observations10.1002/col.20070 ↗
23. Study of origin and composition of coatings in a monument built with granitic rocks, by SEM, XRD, XRF and DTA-TGA10.1002/xrs.1019 ↗
24. Deposition of particles on gypsum-rich coatings of historic buildings in urban and rural environments10.1016/j.conbuildmat.2010.07.001 ↗
25. The cauliflower-like black crusts on sandstones: A natural passive sampler to evaluate the surrounding environmental pollution10.1016/j.envres.2016.02.015 ↗
26. Shackley, M.S. (2011). X-Ray, An Introduction to X-Ray Fluorescence (XRF). Analysis in Archaeology. X-Ray Fluorescence Spectro-Metry (XRF) in Geoarchaeology, Springer.10.1007/978-1-4419-6886-9 ↗
27. Corrosion of 15th and early 16th century stained glass from the monastery of Batalha studied with external ion beam10.1016/j.matchar.2010.12.001 ↗
28. Kumar, G., Rusin, L., Nagar, P.K., Manjul, S.K., Back, M., Benedetti, A., Gurjar, B.R., Ojha, C.S.P., Sharma, M., and Balliana, E. (2025). Characterization of Red Sandstone and Black Crust to Analyze Air Pollution Impacts on a Cultural Heritage Building: Red Fort, Delhi, India. Heritage, 8.10.3390/heritage8060236 ↗
29. First in situ X-ray identification of coesite and retrograde quartz on a glass thin section of an ultrahigh-pressure metamorphic rock and their crystal structure details10.2138/am.2007.2228 ↗
30. Comparative evaluation of the March and generalized spherical harmonic preferred orientation models using X-ray diffraction data for molybdite and calcite powders10.1107/S0021889804031231 ↗
31. A refinement of the crystal structure of gypsum CaSO4·2H2O
32. CIE (Commission Internationale de l’Éclairage) (1976). Official Recommendations on Uniform Color Spaces, Color-Difference Equations and Metric Color Terms, Central Bureau of the CIE. Available online: https://cie.co.at/publications/colorimetry-part-4-cie-1976-lab-colour-space-0.
33. Evaluation of Insulation against Contact Heat, Radiant Heat and Sensory Comfort of Basalt Fabric-Based Composites with Parylene C Coating10.2478/ftee-2023-0050 ↗
34. Microscopy of historic mortars—A review10.1016/j.cemconres.2005.12.006 ↗
35. Investigation of the technology of historic mortars10.1016/S1296-2074(99)00118-1 ↗
36. New dating approach based on the petrographical, mineralogical and chemical characterization of ancient lime mortar: Case study of the archaeological site of Hippo, Annaba city, Algeria10.1186/s40494-023-00942-3 ↗
37. Protocols, pitfalls, and publishing for pXRF analyses: From “know how” to “best practices”
38. Drake, B.L., and MacDonald, B.L. (2022). Appendix A: Element Guide. Advances in Portable X-Ray Fluorescence Spectrometry: Instrumentation, Application and Interpretation, Royal Society of Chemistry. Available online: https://www.rsc.org/suppdata/books/178801/9781788014229/bk9781788014229.pdf.10.1039/9781839162695 ↗
39. Microbially Induced Deterioration of Architectural Heritages: Routes and Mechanisms Involved10.1186/2190-4715-24-36 ↗
40. Microscopic characterisation of black crusts on different substrates
41. Black layers on historical architecture10.1007/s11356-008-0046-8 ↗
42. Study on the mechanism of the black crust formation on the ancient marble sculptures and the effect of pollution in Beijing area10.1016/j.heliyon.2022.e10442 ↗
43. Ruffolo, S.A., La Russa, M.F., Rovella, N., and Ricca, M. (2023). The Impact of Air Pollution on Stone Materials. Environments, 10.10.3390/environments10070119 ↗
44. Problems of analysis by FTIR of calcium sulphate–based preparatory layers: The case of a group of 16th-century Portuguese paintings10.1111/arcm.12026 ↗
45. On the Morphology and Composition of Particulate Matter in an Urban Environment10.4209/aaqr.2017.09.0340 ↗
46. Preparation of superhydrophobic nanocalcite crystals using Box–Behnken design10.1016/j.arabjc.2014.11.003 ↗
47. Dolomite in archaeological plaster: An FTIR study of the plaster floors at Neolithic Motza, Israel
48. Evaluation of ATR-FTIR spectroscopy for distinguish anthropogenic and geogenic calcite10.1088/1742-6596/2204/1/012048 ↗
49. Jordán, M.M., Jordá, J., Pardo, F., and Montero, M.A. (2019). Mineralogical Analysis of Historical Mortars by FTIR. Materials, 12.10.3390/ma12010055 ↗
50. Mechanisms of Air Pollution Damage to Stone10.1142/9781848161283_0003 ↗
51. Mechanisms of Air Pollution Damage to Brick, Concrete and Mortar10.1142/9781848161283_0004 ↗
52. Color changes in architectural limestones from pollution and cleaning10.1002/col.20322 ↗
53. Perez-Monserrat, E.M., Varas-Muriel, M.J., De Buergo, M.A., and Fort, R. (2016). Black Layers of Decay and Color Patterns on Heritage Limestone as Markers of Environmental Change. Geosciences, 6.10.3390/geosciences6010004 ↗
54. Colorimetric Monitoring of Palazzo Margherita, US Embassy in Rome
55. LCA as a Complementary Tool for the Evaluation of Biocolonization Management: The Case of Palazzo Rocca Costaguta10.3390/heritage7120318 ↗
56. Hidden Message in Stone Masonry of Galata Monastery—Iași City, Romania
57. Artefactometrical Assessment of Works of Art by Summing the Impact Grids of Altmetric Quantification
58. Biomineral deposits and coatings on stone monuments as biodeterioration fingerprints10.1016/j.scitotenv.2023.168846 ↗
59. Bergomi, A., Comite, V., Borelli, M., Lombardi, C.A., Festa, E., Oujja, M., Castillejo, M., Maestro-Guijarro, L., Carmona-Quiroga, P.M., and Crespo, A. (2025). Integrated Comprehensive Characterization of Black Crusts from Milan’s Monumental Cemetery: A Synergistic Approach Combining Conventional and Unconventional Analytical Techniques. Heritage, 8.10.3390/heritage8120506 ↗
60. Effect of long-term changes in air pollution and climate on the decay and blackening of European stone buildings
61. Marszałek, M., Dudek, K., and Gaweł, A. (2020). Cement Render and Mortar and Their Damages Due to Salt Crystallization in the Holy Trinity Church, Dominicans Monastery in Cracow, Poland. Minerals, 10.10.5194/egusphere-egu2020-18280 ↗
62. Treatment of salt attack and rising damp in heritage buildings in Penang, Malaysia
63. The impact of salt pore clogging on the hygric properties of bricks10.1016/j.conbuildmat.2017.12.210 ↗
64. Gypsum-induced Decay on Limestone Buildings in the Urban Environment of Budapest/Gipsinduzierter Zerfall des Kalksteins in städtischer Atmosphäre in Budapest
65. Groot, C., Ashall, G.J., and Hughes, J. (2004). Damage Analysis as a Step Towards Compatible Repair Mortars. Characterisation of Old Mortars with Respect to Their Repair, RILEM Publications SARL. Report 28.
66. Mortars and plasters—How to characterize mortar and plaster degradation10.1007/s12520-021-01405-1 ↗
67. Microbial Deterioration and Sustainable Conservation of Stone Monuments and Buildings10.1038/s41893-020-00602-5 ↗
68. Biodeterioration of stone: A review10.1016/S0964-8305(00)00109-8 ↗
69. Study on the efficacy of amorphous calcium carbonate as a consolidant for calcareous matrix10.1186/s40494-022-00804-4 ↗