Microplastic pollution in vulnerable karst environments: case study from the Slovenian classical karst region


  • Lara Valentić Research Centre of the Slovenian Academy of Sciences and Arts, Karst Research Institute, Postojna, Slovenia https://orcid.org/0000-0003-0028-7163
  • Peter Kozel University of Maribor, Faculty of Natural Sciences and Mathematics, Department of Biology, Maribor, Slovenia
  • Tanja Pipan Research Centre of the Slovenian Academy of Sciences and Arts, Karst Research Institute, Postojna, Slovenia https://orcid.org/0000-0003-0028-7163




caves, groundwater, Slovenia, karst, fibres, microplastic contamination


Since the start of mass production of plastic materials more than a century ago, the problem of accumulating plastic waste in the environment has reached epic proportions. Recently, the problem of smaller plastic particles (microplastic, MP) in the environment has become a widely studied topic, but the amount and types of MP in karst environments are still poorly known. Thus, the objective of this study was to collect and analyse samples from various karst habitats and to try and determine the scope of pollution in karst springs that are in part used as sources for drinking water. Of the potential pollution sources, we sampled rainwater, two discharges from wastewater treatment plants, and a leachate from a landfill. We conducted polymer analyses of potential MP particles using FTIR-ATR. The results showed that eight samples from the Postojna region (Postojna–Planina Cave System, rainfall sample and surface streams) contain up to 444 MP particles per m3. However, 32 samples taken from the Škocjan–Kačna–Jama 1 v Kanjaducah Cave System contain up to 60,000 MP particles per m3, with the bulk of particles found in the sediment samples from Škocjan Caves – Kačna Cave System. Samples from Postojna region contained mostly PET, PU and PA polymers, with a minor inclusion of polymers of plastic sponge used for cleaning. Samples from Škocjan region contained mostly PP, PET and PE polymers, with some of PA and PU polymers. Sediment samples contained much less MP particles compared to water samples, which indicates fast transport through karst aquifer.


Download data is not yet available.


Abbasi, S., Keshavarzi, B., Moore, F., Turner, A., Kelly, F. J., Dominguez, A. O. & N. Jaafarzadeh, 2019: Distribution and potential health impacts of microplastics and microrubbers in air and street dusts from Asaluyeh County, Iran.- Environmental Pollution 244, 153-164. https://doi.org/10.1016/j.envpol.2018.10.039

Agencija Republike Slovenije za okolje (ARSO), 2019: Atlas okolja. http://gis.arso.gov.si/atlasokolja/profile.aspx?id=Atlas_Okolja_AXL@Arso&culture=en-US (19.8.2020)

Akdogan, Z. & B. Guven, 2019: Microplastics in the environment: A critical review of current understanding and identification of future research needs.- Environmental Pollution 254, 113011. https://doi.org/10.1016/j.envpol.2019.113011

Allen, S., Allen, D., Phoenix, V. R., Le Roux, G., Durántez Jiménez, P., Simonneau, A., Binet, B. & D. Galop, 2019: Atmospheric transport and deposition of microplastics in a remote mountain catchment.- Nature Geoscience 12, 339-344. https://doi.org/10.1038/s41561-019-0335-5

Arsenović, D., 2007: The influence of tourism on the cave environment.- Diploma thesis, University of Ljubljana, Faculty of Arts, Department of geography, pp.220, Ljubljana. https://repozitorij.uni-lj.si/IzpisGradiva.php?id=23430 (1.2.2022)

Bakir, A., Rowland, S. J. & R. C. Thompson, 2012: Competitive sorption of persistent organic pollutants onto microplastics in the marine environment.- Marine Pollution Bulletin 64, 12, 2782-2789. https://doi.org/10.1016/j.marpolbul.2012.09.010

Balestra, V. & R. Bellopede, 2022: Microplastic pollution in show cave sediments: First evidence and detection technique.- Environmental pollution 292, 118261. https://doi.org/10.1016/j.envpol.2021.118261

Besseling, E., Foekema, E. M., Van Franeker, J. A., Leopold, M. F., Kühn, S., Bravo Rebolledo, E. L., Heße, E., Mielke, L., IJzer, J., Kamminga, P. & A. A. Koelmans, 2015: Microplastic in a macro filter feeder: Humpback whale Megaptera novaeangliae.- Marine Pollution Bulletin 95, 248-252. https://doi.org/10.1016/j.marpolbul.2015.04.007

Bonacci, O., Pipan, T. & D. C. Culver, 2009: A framework for karst ecohydrology. Environmental Geology 56, 5, 891-900. https://doi.org/10.1007/s00254-008-1189-0

Cantonati, M., Stevens, L. E., Segadelli, S., Springer, A. E., Goldscheider, N., Celico, F., Filippinig, M., Ogatah, K. & A. Gargini, 2020: Ecohydrogeology: The interdisciplinary convergence needed to improve the study and stewardship of springs and other groundwater-dependent habitats, biota, and ecosystems.- Ecological Indicators 110, 105803. https://doi.org/10.1016/j.ecolind.2019.105803

Centa, M., 2016: Assessment of microplastic concentrations in Slovenian watercourses and lakes. University of Ljubljana, Faculty of Civil and Geodetic Engineering, Master's thesis, pp.144, Ljubljana. https://repozitorij.uni-lj.si/Dokument.php?id=97837&lang=eng (1.2.2022)

Chen, G., Feng, Q. & J. Wang, 2020: Mini-review of microplastics in the atmosphere and their risks to humans.- Science of the Total Environment 703, 1-6. https://doi.org/10.1016/j.scitotenv.2019.135504

Chen, Z., Auler, A.S., Bakalowicz, M., Drew, D., Griger, F., Hartmann, J., Jiang, G.H., Moosdorf, N., Richts, A., Stevanovic, Z., Veni, G. & N. Goldscheider, 2017: The World Karst Aquifer Mapping project: concept, mapping procedure and map of Europe.- Hydrogeology Journal 25, 3, 771-785. https://doi.org/10.1007/s10040-016-1519-3

Cheung, P.K. & L. Fok, 2016: Evidence of microbeads from personal care product contaminating the sea.- Marine Pollution Bulletin 109, 582-585. https://doi.org/10.1016/j.marpolbul.2016.05.046

Cincinelli, A., Scopetani, C., Chelazzi, D., Lombardini, E., Martellini, T., Katsoyiannis, A., Fossi, M. C. and Corsolini, S., 2017. Microplastic in the surface waters of the Ross Sea (Antarctica): Occurrence, distribution and characterization by FTIR.- Chemosphere 175, 391-400. http://dx.doi.org/10.1016/j.chemosphere.2017.02.024

Culver, D. C. & T. Pipan, 2019: The biology of caves and other subterranean habitats. 2nd ed. Oxford University Press, pp. 336, Oxford.

Culver, D. C., Debevec, B., Knez, M., Kovačič, G., Kranjc, A., Mulec, J., Semeja, A., Slabe, T., Šebela, S. & N. Zupan Hajna, 2012: Karstology and development challenges on Karst II – Construction, tourism, ecology, protection. ZRC Publishing, ZRC SAZU, pp. 199, Postojna-Ljubljana. https://doi.org/10.3986/9789610503330

Dris, R., Gasperi, J., Rocher, V., Saad, M., Renault, N. & B. Tassin, 2015: Microplastic contamination in an urban area: a case study in Greater Paris.- CSIRO Publishing, Environmental Chemistry 12, 5, 592-299. http://dx.doi.org/10.1071/EN14167

Eerkes-Medrano, D., Thompson, R. C. & D. C. Aldridge, 2015: Microplastics in freshwater systems: A review of the emerging threats, identification of knowledge gaps and prioritisation of research needs.- Water Research 75, 63-82. http://dx.doi.org/10.1016/j.watres.2015.02.012

Ford, D. & P. Williams, 2007: Karst hydrogeology and geomorphology. John Wiley & Sons, Chichester, pp. 562.

Fossi, M. C., Panti, C., Guerranti, C., Coppola, D., Giannetti, M., Marsili, L. & R. Minutoli, 2012: Are baleen whales exposed to the threat of microplastics? A case study of the Mediterranean fin whale (Balaenoptera physalus).- Marine Pollution Bulletin 64, 2374-2379. http://dx.doi.org/10.1016/j.marpolbul.2012.08.013

Gabrovšek, F. & J. Turk, 2011: Water temperature as a natural tracer of groundwater in karst: the case of the Pivka and Unica Rivers. In: Knez, M. et al. (eds.): Karstology and development challenges on karst I – Water. ZRC Publishing, ZRC SAZU Ljubljana, pp. 38-46, Ljubljana. https://doi.org/10.3986/9789610502999

Gams, I., 1974: Concentration of CO2 in the caves in relation to the air circulation (in the case of Postojna cave).- Acta Carsologica 6, 183-192.

Goeppert, N. & N. Goldscheider, 2021: Experimental field evidence for transport of microplastic tracers over large distances in an alluvial aquifer.- Journal of Hazardous Materials 408, 124844. https://doi.org/10.1016/j.jhazmat.2020.124844

Goldscheider, N., 2019: A holistic approach to groundwater protection and ecosystems services in karst terrains.- Carbonates and Evaporites 34, 1241-1249. https://doi.org/10.1007/s13146-019-00492-5

Goldscheider, N., Chen, Z., Auler, A. S., Bakalowicz, M., Broda, S., Drew, D., Hartmann, J., Jiang, G., Moosdorf, N., Stevanovic, Z. & G. Veni1, 2020: Global distribution of carbonate rocks and karst water resources.- Hydrogeology Journal 28, 1661-1677. https://doi.org/10.1007/s10040-020-02139-5

Goldscheider, N., & D. Drew, 2007: Methods in Karst Hydrogeology. Taylor and Francis Group, pp. 280, Leiden, Netherlands. https://doi.org/10.1201/9781482266023

Hammer, Ø., Harper, D. A. T. & P. D. Ryan, 2001: PAST: Paleontological statistics software package for education and data analysis.- Palaeontologia Electronica 4, 1, 9. Available at: http://priede.bf.lu.lv/ftp/pub/TIS/datu_analiize/PAST/2.17c/download.html (19.11.2020)

Hidalgo-Ruz, V., Gutow, L., Thompson, R. C. & M. Thiel, 2012: Microplastics in the Marine Environment: A Review of the Methods Used for Identification and Quantification.- Environmental Science & Technology 46, 3060-3075. https://doi.org/10.1021/es2031505

Horton, A. A., Walton, A., Spurgeon, D.J., Lahive, E. & C. Svendsen, 2017: Microplastics in freshwater and terrestrial environments: Evaluating the current understanding to identify the knowledge gaps and future research priorities.- Science of the Total Environment 586, 127-141. http://dx.doi.org/10.1016/j.scitotenv.2017.01.190

Imhof, H. K., Ivleva, N. P., Schmid, J., Niessner, R. & C. Laforsch, 2013: Contamination of beach sediments of a subalpine lake with microplastic particles.- Current Biology 23, 19, 867-868. https://doi.org/10.1016/j.cub.2013.09.001

Ismail, A. A., van de Voort, F. R. & J. Sedman, 1997: Fourier Transform Infrared Spectroscopy: Principles and Applications. In: Paré, J. R. J. & J. M. R. Bélanger (eds.): Instrumental Methods in Food Analysis. https://doi.org/10.1016/S0167-9244(97)80013-3

Kluge, T., Reichelman, D. F. C., Wieser, M., Spötl, C., Sültenfuß, J., Schröder-Ritzrau, A., Niggemann, S. & W. Aeschbach-Hertig, 2010: Dating cave drip water by tritium.- Journal of Hydrology 394, 396-406. https://doi.org/10.1016/j.jhydrol.2010.09.015

Kogovšek, J., 2011: The role of the vadose zone in the transfer of pollution through karst aquifers to karst springs. In: Knez, M. et al. (eds.): Karstology and development challenges on karst I – Water. ZRC Publishing, ZRC SAZU Ljubljana, pp. 20–37. https://doi.org/10.3986/9789610502999

Kogovšek, J., 2010: Characteristics of percolation through the karst vadose zone. ZRC Publishing, pp. 168, Ljubljana, Slovenia.

Kovačič, G. & N. Ravbar, 2013: Analysis of human induced changes in a karst landscape – the filling of dolines in the Kras plateau, Slovenia.- Science of the Total Environment 447, 143-151. https://doi.org/10.1016/j.scitotenv.2013.01.002

Li, J., Liu, H. & J. P. Chen, 2018: MPs in freshwater systems: a review on occurrence, environmental effects, and methods for MPs detection.- Water Research 137, 362-374. https://doi.org/10.1016/j.watres.2017.12.056

Lithner, D., Larsson, Å. & D. Göran, 2011: Environmental and health hazard ranking and assessment of plastic polymers based on chemical composition.- Science of the Total Environment 409, 18, 3309-3324. https://doi.org/10.1016/j.scitotenv.2011.04.038

Liu, K., Wang, X., Fang, T., Xu, P., Zhu, L. & D. Li, 2019: Source and potential risk assessment of suspended atmospheric microplastics in Shanghai.- Science of the Total Environment 675, 462-471. https://doi.org/10.1016/j.scitotenv.2019.04.110

Lwanga, E. H., Vega, J. M., Ku Quej, V., de los Angeles Chi, J., Sanchez del Cid, L., Chi, C. Segura, G. E., Gertsen, H., Salánki, T., van der Ploeg, M., Koelmans, A. A. & V. Geissen, 2017: Field evidence for transfer of plastic debris along a terrestrial food chain.- Scientific Reports 7: Article number 14071. https://doi.org/10.1038/s41598-017-14588-2

Mintenig, S. M., Löder, M. G. J., Primpke, S. & G. Gerdts, 2019: Low numbers of microplastics detected in drinking water from ground water sources.- Science of the Total Environment 648: 631-635. https://doi.org/10.1016/j.scitotenv.2018.08.178

Moore, C. J., Lattin, G. L. & A. F. Zellers, 2011: Quantity and type of plastic debris flowing from two urban rivers to coastal waters and beaches of Southern California.- Journal of Integrated Coastal Zone Management 11, 1, 65-73. https://www.cleanwater.org/files/publications/C%20Moore%20et%20al%202%20urban%20rivers.pdf (19.8.2020)

Mulec, J., 2019: Lampenflora. In: White, W. B. et al. (eds.): Encyclopedia of caves, 3rd ed. Elsevier/Academic Press, pp. 635-641, London, United Kingdom. https://doi.org/10.1016/B978-0-12-814124-3.00075-3

Mulec, J., 2014: Human impact on underground cultural and natural heritage sites, biological parameters of monitoring and remediation actions for insensitive surfaces: Case of Slovenian show caves.- Journal for Nature Conservation 22, 132-141. http://dx.doi.org/10.1016/j.jnc.2013.10.001

Palatinus, A., Kovač Viršek, M. & E. Kaberi, 2015: DeFishGear protocols for sea surface and beach sediment sampling and sample analysis. http://mio-ecsde.org/wp-content/uploads/2014/12/Protocols-sea-surfacebeach-sediments-Feb15.pdf (19.8.2020).

Panno, S. V., Kelly, W. R., Scott, J., Zheng, W., McNeish, R. E., Holm, N., Hoellein, T. J. & E. L. Baranski, 2019: Microplastic contamination in karst groundwater systems.- Ground Water 57, 2, 189-196. https://doi.org/10.1111/gwat.12862

Petrič, M., Ravbar, N. & J. Kogovšek, 2011: Characteristics of karst aquifers, their vulnerability and endangerment. In: Knez, M. et al. (eds.): Karstology and development challenges on karst I – Water. ZRC Publishing, ZRC SAZU Ljubljana, pp. 7–19, Ljubljana. https://doi.org/10.3986/9789610502999

Pike Technologies, 2018: GladiATR – Highest Performance Diamond ATR data sheet. Available at: https://www.piketech.com/files/pdfs/PIKE_GladiATR_Data_Sheet.pdf (27.10.2020)

Pipan, T., 2005: Epikarst – a promising habitat. Copepod fauna, its diversity and ecology: a case study from Slovenia (Europe). Carsologica 5, ZRC Publishing, Karst Research Institute at ZRC SAZU Ljubljana; pp. 101, Postojna, Ljubljana,.

Prelovšek, M., Gabrovšek, F., Kozel, P., Mulec, J., Pipan, T. & S. Šebela, 2021: The Škocjan Caves – UNESCO World Heritage Site.- Zeitschrift fur Geomorfologie 62, 3, 49-64.

Ravbar, N., 2007: The protection of karst waters. A comprehensive Slovene approach to vulnerability and contaminant risk mapping. ZRC Publishing, ZRC SAZU Ljubljana, pp. 256, Ljubljana. https://zalozba.zrc-sazu.si/p/805 (2.3.2021)

Ravbar, N. & G. Kovacic, 2015: Vulnerability and protection aspects of some Dinaric karst aquifers: a synthesis.- Environmental Earth Sciences 74, 129-141. https://doi.org/10.1007/s12665-014-3945-7

Schmidt, C., Krauth, T., & S. Wagner, 2017: Export of Plastic Debris by Rivers into the Sea.- Environmental Science & Technology 51, 12246-12253. htpps://doi.org/10.1021/acs.est.7b02368

Setälä, O., Fleming-Lehtinen, V. & M. Lehtiniemi, 2014: Ingestion and transfer of microplastics in the planktonic food web.- Environmental Pollution 185, 77-83. https://doi.org/10.1016/j.envpol.2013.10.013

SpecialChem, the material selection platform, 2020: Hydrocerol ® technical datasheet. Available at: https://polymer-additives.specialchem.com/product/a-clariant-hydrocerol (3.11.2020).

Stevanović, Z., 2019: Karst waters in potable water supply: a global scale overview.- Environmental Earth Sciences 78, 662. https://doi.org/10.1007/s12665-019-8670-9

Šebela, S., 2019: Postojna – Planina Cave System, Slovenia. In: White, W.B. et al. (eds.): Encyclopedia of caves, 3rd ed. Elsevier/Academic Press, pp. 812-821, London, United Kingdom. https://doi.org/10.1016/B978-0-12-814124-3.00098-4

Šebela, S., Turk, J. & T. Pipan, 2015: Cave micro-climate and tourism: Postojnska jama, Slovenia.- Cave and Karst Science 42, 2, 78-85.

Talvitie, J., Mikola, A., Setälä, O., Heinonen, M. & A. Koistinen, 2017: How well is microlitter purified from wastewater? – A detailed study on the stepwise removal of microlitter in a tertiary level wastewater treatment plant.- Water Research 109, 164-172. https://doi.org/10.1016/j.watres.2016.11.046

Tomazin, R., Simčič, S., Matos, T., Kopitar, A. N., Stopinšek, S., Mauko Pranjić, A., Zalar Serjun, V. & J. Mulec, 2018: Tourists impact on air quality in Postojna Cave and Škocjan Caves (Slovenia) In: Prelovšek, M. (ed.): Show caves and science: abstracts & guide book. Založba ZRC, pp. 95, Ljubljana. https://iks.zrc-sazu.si/wp-content/uploads/2019/12/IKS-26-Guide-book-2018-2.pdf (1.3.2021)

Valentić, L., 2018: Analysis of microplastics in selected surface and underground karst waters. Master's thesis, University of Nova Gorica, Faculty of Environmental Sciences, pp. 194, Nova Gorica. http://repozitorij.ung.si/IzpisGradiva.php?id=4027&lang=eng (19.8.2020)

Vižintin, G., Ravbar, N., Janež, J., Koren, E., Janež, N., Zini, L. Treu, F. & M. Petrič, 2018: Integration of models of various types of aquifers for water quality management in the transboundary area of the Soča/Isonzo river basin (Slovenia/Italy).- Science of the Total Environment 619-620, 1214-1225. https://doi.org/10.1016/j.scitotenv.2017.11.017

Wada, Y., van Beek, L. P. H., van Kempen, C.M., Reckman, J. W. T. M., Vasak, S. & M. F. P. Bierkens, 2010: Global depletion of groundwater resources.- Geophysical Research Letters 37, 20, L20402. https://doi.org/10.1029/2010GL044571

Wang, J., Wang, M., Ru, S. & X. Liu, 2019: High levels of microplastic pollution in the sediments and benthic organisms of the South Yellow Sea, China.- Science of the Total Environment 651, 1661-1669. https://doi.org/10.1016/j.scitotenv.2018.10.007

White, W. B., 2019: Hydrogeology of Karst aquifers. In: White, W. B. et al. (eds.): Encyclopedia of Caves, 3rd edition. Academic press, pp. 537-545. https://doi.org/10.1016/b978-0-12-814124-3.00064-9

Woodall, L. C., Sanchez-Vidal, A., Canals, M., Paterson, G. L. J., Coppock, R., Sleight, V. Calafat, A., Rogers, A. D., Narayanaswamy, B. E. & R. C. Thompson, 2014: The deep sea is a major sink for microplastic debris.- Royal Society Open Science 1, 4, 1-8. https://doi.org/10.1098/rsos.140317

Zhanga, Y., Kanga, S., Allenc, S., Allenc, D., Gao, T. & M. Sillanpää, 2020. Atmospheric microplastics: A review on current status and perspectives.- Earth-Science Reviews 203, 103118. https://doi.org/10.1016/j.earscirev.2020.103118



2022-12-08 — Updated on 2022-12-13


How to Cite

Valentić, L., Kozel, P., & Pipan, T. (2022). Microplastic pollution in vulnerable karst environments: case study from the Slovenian classical karst region. Acta Carsologica, 51(1), 79–92. https://doi.org/10.3986/ac.v51i1.10597 (Original work published December 8, 2022)



Original papers