This is the first survey to investigate the occurrence and extent of microplastic contamination in sediments collected during the autumn of 2019 at five locations from the coastal area of the Boka Kotorska Bay on the Montenegrin coast. Microparticles in sediments were isolated by density separation in saturated aqueous NaCl-solutions and visually analyzed using an Olympus SZX16 microscope. Microplastic debris extracted from five samples of sediments were counted. The primary shape types by number were: filaments (78.61 %), fragments (8.56 %), granules (7.22 %), and films (5.61). All five sites sampled in 2019 were contaminated with microplastic particles, in the following sequence: Dobrota (68.72 %) > Bijela (12.57 %) > Tivat (7.75 %) > Sveta Nedjelja (6.42 %) > Orahovac (4.55 %)

Bajt, Oliver

Bošković, Neda

Joksimović, Danijela

Peković, Milica

English

Digital repository of Slovenian research organizations

Studia Marina 2020, 33 (1): 18-25             UDC: 551.462:504.5 (497.16 Boka Kotorska) Original scientific paper   DOI: 10.5281/zenodo.3932076  18   Мicroplastics in sediments from the coastal area of the Boka Kotorska Bay on the Montenegrin coast  Neda BOŠKOVIĆ*1, Danijela JOKSIMOVIĆ1, Milica PEKOVIĆ1, Oliver BAJT2 1Institute of Marine Biology, University of Montenegro, Put I bokeljske brigade 68, 85330 Kotor, Montenegro, *e-mail: nedaboskovic93@gmail.com 2National Institute of Biology, Marine Biology Station Piran, Fornače 41, 6330 Piran, Slovenia   ABSTRACT    This is the first survey to investigate the occurrence and extent of microplastic contamination in sediments collected during the autumn of 2019 at five locations from the coastal area of the Boka Kotorska Bay on the Montenegrin coast. Microparticles in sediments were isolated by density separation in saturated aqueous NaCl-solutions and visually analyzed using an Olympus SZX16 microscope. Microplastic debris extracted from five samples of sediments were counted. The primary shape types by number were: filaments (78.61 %), fragments (8.56 %), granules (7.22 %), and films (5.61). All five sites sampled in 2019 were contaminated with microplastic particles, in the following sequence: Dobrota (68.72 %) > Bijela (12.57 %) > Tivat (7.75 %) > Sveta Nedjelja (6.42 %) > Orahovac (4.55 %).   Keywords: microplastics, sediment, Boka Kotorska Bay, Montenegro    INTRODUCTION  Microplastics in aquatic ecosystems and especially in the marine environment represent pollution of increasing scientific and societal concern, and hence the assessment of its extent in the Montenegro marine environment. Microplastics (MPs) are ubiquitous plastic particles smaller than five millimeters  (5 mm) in size (GESAMP, 2015). MPs were first scientifically recorded in North America    along the coast of New England in the 1970s (Carpenter et al., 1972).There are two categories of MPs: primary and secondary. Primary MPs include plastic particles that are purposefully manufactured as small, while secondary MPs are resulting from the degradation of macroplastics due to mechanical, photolytic and/or chemical degradation processes in the marine environment (Masura et al., 2015). MPs have been reported in the water column and marine sediments worldwide (Moore et al., 2001; Thompson et al., 2004; Studia Marina 2020, 33 (1): 18-25 19  Law et al., 2010; Claessens et al., 2011). The accumulation of MPs in marine sediments was documented, by the literature, for the first time in 2004 (Thompson et al., 2004). Particles accumulated in the sediment are accessible to benthic suspension and deposit feeders (Deudero et al., 2014; Van Cauwenberghe et al., 2015a) and other sediment-dwelling organisms (Moore, 2008; Wright et al., 2013). Reports of MPs in marine sediments worldwide are emerging, remarking the large spatial distribution of this contaminant and therefore the possible implications which MPs might have in marine habitat, food webs (Claessens et al., 2011; Vianello et al., 2013; Van Cauwenberghe et al., 2015a). The purpose of our study was visual identification (number of, shape, type and colour of the particles) MPs in sediments collected during the autumn of 2019 at five locations from the coastal area of the Boka Kotorska Bay on the Montenegrin coast, and obtaining the first assessment of this type of pollution for the area.   MATERIAL AND METHODS  Samples of surface sediment were collected at five selected locations in the Boka Kotorska Bay, Montenegrin coastline: Dobrota, Orahovac, Sveta Nedjelja, Tivat and Bijela, during the autumn of 2019 (Fig. 1).  Sediment samples were collected for analysis using Van Veen grab, stored  in  the  Figure 1. Map of investigated area   aluminium container, frozen at -18 °C and freeze-dried at -40 °C for 48 h (CHRIST, Alpha 2-4 LD plus, Germany). For MPs density separation, we used a method proposed by Thompson et al. (2004). The method is based on the usage of the concentrated NaCl solution (1.2 g/dm3). After sedimentation of 24 hours, the solution was decanted. The supernatant was sieved through the 63 μm steel sieve. The material retained on the sieve was rinsed with Mili-Q water to a glass Petri dish. The procedure was repeated two times for each sample. Then, the sediment samples were filtered using a vacuum pump on to fiberglass filters (Whatman GF-F, diam. 47 mm, nominal porosity 0.7 mm). These samples were analyzed under a microscope to identify and count the number of MPs particles and fibres, present in the sample. Visual analysis of particles was performed using an Olympus SZX16 imaging microscope (DP-Soft software).  Pictures of the particles obtained under a microscope (Fig. 2) were taken using ImageJ software (ver. 2.0.0) and classified into four types (Claessens et al., 2011), according to their shape (filaments, granules, films and fragments).  Studia Marina 2020, 33 (1): 18-25 20   Figure 2. Pictures of the different types and colours of MPs particle in the sediment of the Boka Kotorska Bay, Montenegrin coast: (a-c) filaments; (d-h) fragments; (i-k) films and (l-n) granules   RESULTS AND DISCUSSION  Results of different types and colour of MPs particle in five sediment samples of Boka Kotorska Bay, expressed as total number of each class recovered per 100 g dry weight of sediment, are presented in Table 1. The number of filaments in the location Dobrota was the highest compared with all other examined locations. Filaments, fragments and films were present in the sediment at all locations, while granules were present in three locations (Sveta Nedjelja, Tivat and Bijela). Eight different colours of MPs were observed in the present study. In all five sampled, coloured particles were found. The most frequent MP colour observed for all studied locations was: blue > clear > black > red > blue-white > green > yellow > white. The primary MPs shape types collected in the sediments of the Boka Kotorska Bay by number were: filaments (78.61 %), fragments (8.56 %), granules (7.22 %) and films (5.61 %), with filaments being the most dominant type of shape MPs (Fig. 3a). All five locations sampled in 2019 were contaminated with MPs particles. Contamination of locations, based on percentage representation (%) of microplastic particles recovered per 100 g dry weight in five sediment samples, were as follows: Dobrota (68.72 %) > Bijela (12.57 %) > Tivat (7.75 %) > Sveta Nedjelja (6.42 %) > Orahovac (4.55 %) (Fig. 3b). The most contaminated location was Dobrota, while other locations contained a very small quantity of MPs. Comparison of results from literature date is difficult and subject to uncertainty due to different sampling and analysis protocols implemented by researchers used for density separation, enumeration and identification method, and size of MPs, and to the lack of standardized normalization units (Abidli et al., 2018). The comparison of MP concentrations in sediments of five sampling locations of the present study showed that higher levels were usually observed in areas of dense human population and high industrial activities as Dobrota (Andradi, 2011; Brovne et al., 2011; Van Cauvenberghe et al., 2015b).  Except for the location Dobrota, marine sediments in the present study were moderately polluted with MPs compared to heavily polluted regions like the Lagoon of Cabrera Island, Spain (Alomar et al., 2016).  Studia Marina 2020, 33 (1): 18-25 21  Table 1. Results of MPs particle in five sediment samples of Boka Kotorska Bay  * (C) – clear; (W) – white; (B) – blue; (BW) – blue-white; (BL) – black; (G) – green; (R) – red; (Y) – yellow   .   Figure 3. Percentage distribution (%) of MPs particle in sediments of the Boka Kotorska Bay, according to a) shape type and b) representation of microplastic particles in five sediment samples.  The concentrations of MPs in this study were higher than those measured in non-contaminated environments like the French, Belgian, and the Netherlands (North Sea coast), South of Portugal (Van Cauwenberghe et al., 2015b; Frias et al., 2016). According to research conducted in the Central Adriatic Sea, Mistri et al. (2017) revealed that dominant types were filaments followed by fragments, what is confirmed with our results. The percentage of different shape types of MPs in this study was similar to the results from Italy (Mistri et al., 2017). In the Telascica Bay (Eastern Adriatic), Blăsković et al. (2017) found that filaments represented 90% of all seafloor plastics. The high number of fibres and fragments suggests the breakdown of larger plastic items into secondary MPs (through mechanical forces, by photolysis, thermo-oxidation, thermal degradation, via biodegradation processes) (Laglbauer et al., Studia Marina 2020, 33 (1): 18-25 22  2014; Abidli et al., 2018). In the same context, Browne et al. (2011) showed that up to 80% of MPs in sediment was from wastewater effluent. In the present study, MPs reported different colours, which is consistent with other studies on MPs (Nor and Obbard 2014; Zhao et al. 2014; Abidli et al., 2017) which implies that particles may have originated from multiple sources (Munari et al., 2017;  Abidli et al., 2018).   CONCLUSIONS  MPs were found in all five sampling locations from the Boka Kotorska Bay, Montenegrian coast. Marine sediments in the present study are moderately polluted with MPs compared with literature data. The comparison of the high MP contamination registered in location Dobrota to the other locations of the present study showed that higher levels were usually observed in areas with high population density and high industrial activities i.e., with magnified anthropogenic activity. Also, Dobrota is located in the most secluded part of the Bay of Kotor, which means that it is a place with reduced contact with the open sea. This study gives a first insight into MP pollution and provides information on the spatial distribution of MP particles in the Boka Kotorska Bay. The results of MP contamination in this study are just preliminary and require further and detailed analyzes to confirm whether all found particles are microplastics or natural materials.  The obtained results represent the beginning of research that will continue in order to obtain chemical identification the types of MPs polymers using Infrared Spectroscopy (FTIR-ATR).   ACKNOWLEDGEMENTS    This research resulted within the PROMIS (No 3173) project funded by the Ministry of Science of Montenegro.   REFERENCES  Abidli, S., Antunes, J. C., Ferreira, J. L., Lahbib, Y., Sobral, P., & Trigui El Menif, N. (2018): Microplastics in sediments from the littoral zone of the north Tunisian coast (Mediterranean Sea). Estuarine, Coastal and Shelf Science, 205, 1-9. Abidli, S., Toumi, H., Lahbib, Y. & Trigui El Menif, N. (2017): The First Evaluation of Microplastics in Sediments from the Complex Lagoon-Channel of Bizerte (Northern Tunisia). Water Air Soil Pollut., 228:262. Alomar, C., Estarellas, F. & Deudero, S. (2016): Microplastics in the Mediterranean Sea: deposition in coastal shallow sediments, spatial variation and preferential grain size. Mar. Environ. Res., 115, 1–10. Andrady, A. L. (2011): Microplastics in the marine environment. Mar. Pollut. Bull. 62, 1596–1605. Blasković, A., Fastelli, P., Čižmek, H., Guerranti, C. & Renzi, M. 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Shelf Sci. 130, 54–61. Wright, S.L., Thompson, R.C. & Galloway, T.S. (2013): The physical impacts of microplastics on marine organisms: a review. Environ. Pollut. 178, 483e492. Zhao, S., Zhu, L., Wang, T. & Li, D. (2014): Suspended microplastics in the surface water of the Yangtze Estuary System, China: first observations on occurrence, distribution. Mar. Pollut. Bull. 86, 562–5.    Received: 10. 05. 2019. Accepted: 25. 06. 2019. Studia Marina 2020, 33 (1): 18-25 25    Mikroplastika u obalnom sedimentu Bokokotorskog zaliva na crnogorskom primoriju  Neda BOŠKOVIĆ, Danijela JOKSIMOVIĆ, Milica PEKOVIĆ, Oliver BAJT    SAŽETAK  Ovo istraživanje po prvi put mapira i ispituje pojavu i stepen kontaminacije mikroplastike u sedimentu koji je sakupljen sa pet lokacija u priobalnom dijelu Bokokotorskog zaliva na crnogorskom primoriju tokom jeseni 2019. godine. Mikroplastične čestice u sedimentu su izolovane razdvajanjem gustine primjenom zasićenog rastvora NaCl i vizuelno analizirane koristeći optički mikroskop Olympus SZX16. Na ovaj način ekstrahovane mikroplastične čestice iz sedimenta sa svih pet lokacija su izbrojane prema primarnim oblicima na sledeći način:  filamenti (78.61 %), fragmenti (8.56 %), granule (7.22 %) i filmovi (5.61). Takođe, iz dobijenih rezultata smo sagledali i kontaminaciju mikroplastikom prema mjestu uzorkovanja sa sledećom procentualnom zagađenošću: Dobrota (68.72 %) > Bijela (12.57 %) > Tivat (7.75 %) > Sveta Nedjelja (6.42 %) > Orahovac (4.55 %).         Ključne riječi: mikroplastika, sediment, Bokokotorski zaliv, Crna Gora   

Microplastics in sediments from the coastal area of the Boka Kotorska Bay on the Montenegrin coast

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Microplastics in sediments from the coastal area of the Boka Kotorska Bay on the Montenegrin coast

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