A review of plastic pollution in aquatic ecosystems of Turkey

Combined Effects of Treatment and Sewer Connections to Reduce Future Microplastic Emissions in Rivers

Global mitigation strategies are needed to reduce the amount of microplastics reaching our oceans via rivers. However, what strategies will be most effective, and when and where to implement these strategies is unclear. We applied the global water quality model MARINA-Plastics, covering 10,226 sub-basins worldwide, to assess the effects of different emission reduction strategies on microplastic inputs to rivers worldwide over the period 2010-2100, taking time steps of 10 years. We applied four scenarios: three focused on wastewater treatment technologies, ranging from high to low technology improvement levels, and one combining high technology in wastewater treatment with source-oriented measures. The results show that the combined strategy of high wastewater treatment and source-oriented measures is expected to be the most effective for reducing future microplastics in rivers on a global scale. By 2100, this combined strategy is expected to result in a 68% microplastic reduction in global rivers compared to 2010. African rivers will be the main hotspots, receiving more than five times more microplastics in 2100 than in 2010. In 2100, wear from car tires is expected to be the dominant source of microplastics globally. Our insights support the implementation of the European Green Deal and the realization of Sustainable Development Goal 6 (clean water).

High microplastic pollution in marine sediments associated with urbanised areas along the SW Bulgarian Black Sea coast

This study aims to provide baseline data on microplastic (MP) concentrations in beach and seabed sediments of the SW Black Sea coast, and to identify possible sources of MP pollution in the area. MP concentrations in beach sediments in urbanised coastal areas, as well as in all seabed sediments, were on average higher than in other parts of the Black Sea and most other European seas. Urban coastal areas showed the highest average MP concentrations (mean ± SD): 464.44 ± 272.50 MP·kg-1 dry sediment in beach samples, 825.93 ± 396.30 MP·kg-1 dry sediment in seabed samples, while coastal sediments in an area with no local anthropogenic activities had significantly lower average MP concentrations: 84.44 ± 147.57 MP·kg-1 in beach samples, and 550.62 ± 245.71 MP·kg-1 in seabed samples. Possible identified sources of MPs include sewage water discharges, urban waste, coastal fisheries and aquaculture, as well as accumulation of marine litter on beaches and in adjacent offshore areas, serving as sources of secondary MP pollution.

How much do we know about the microplastic distribution in the Mediterranean Sea: A comprehensive review

The Mediterranean Sea is one of the most heavily polluted regions. Here we comprehensively review the current state of microplastic pollution in the Mediterranean Sea and the Black Sea. A total of 284 studies published between 2012 and 2023 were analyzed, revealing a continuous increase in research efforts. Our review encompassed microplastic monitoring studies across five environmental matrices: the sea surface, water column, intertidal sediment, bottom sediment, and biota, with a predominant focus observed in biota-related studies with fish, molluscs, crustaceans, and echinoderms being the primary focus. The study found that species such as Mullus barbatus, Mytilus galloprovincialis, Nephrops norvegicus, and Holothuria tubulosa are frequently studied species. The review also emphasizes the lack of standardized methodologies across studies, which hampers the comparability of results and the synthesis of data. The findings of this study provide a critical evaluation of the current research landscape and identify significant knowledge gaps, particularly in the underrepresented southern Mediterranean and Black Sea regions, calling for more balanced research efforts and methodological consistency in future studies.

Microplastic accumulation in a lizard species: Observations from the terrestrial environments

Microplastics are a global environmental problem, polluting both aquatic and terrestrial environments. Terrestrial lizards are suitable model organisms to study human-induced pollution in these areas, as they can live in urbanized areas where microplastics are most abundant. Therefore, we analyzed the prevalence of microplastics (MPs) in a common Lacertid lizard, the snake-eyed lizard, Ophisops elegans. We detected MPs in the gastrointestinal tract (GIT) of 33 of 152 specimens from 18 populations. The detected MPs had six distinct polymer compositions, namely Polyethylene terephthalate, Polyacrylonitrile, Polypropylene, Polyethylene, Poly methyl methacrylate and Polyamide. The majority of these MPs were fiber-type and the dominant color was navy blue. The lengths of MPs varied from 37 to 563 μm, with an average length of 175 μm. MPs were detected in the GITs of 43% of juveniles (n = 7), 30% of males (n = 105), and 18% of females (n = 40), with a mean of 0.27 per specimen. Furthermore, we found that microplastic densities varied with habitat distance from human settlements, supporting the theory that high levels of microplastic contamination are associated with extensive anthropogenic activity.

The presence of microplastics in Baran's newt (Neurergus barani Öz, 1994) and the spotted newt (Neurergus strauchii Steindachner, 1887)

Microplastics (MPs), tiny plastic particles less than 5 mm in size, have emerged as a common and worrying pollutant in marine, freshwater, and terrestrial environments worldwide. In this study, we revealed the microplastic exposure of two endemic newt species for Türkiye. We found that polyethylene terephthalate (PET) was the predominant microplastic polymer type in both species, with the blue fiber shape in particular. We also found that there was a negative correlation between microplastic size and gastrointestinal tract (GIT) weight, but there was no significant difference between body length and GIT weight of both species. Our findings might be surprising as the studied species live in natural spring waters in remote, high-altitude areas. However, the detection of water bottles in their habitats appears to be the reason for their exposure to microplastic pollution. Therefore, reducing the use of single-use plastics is predicted to contribute to the conservation of these endemic newts.

Spatial distribution and characteristics of plastic pollution in the salt marshes of Bahía Blanca Estuary, Argentina

This study delves into the magnitude and attributes of plastic pollution in the salt marshes of the Bahía Blanca Estuary, Argentina, with a specific focus on its spatial distribution. The investigation included the evaluation of microplastics (1-5 mm), mesoplastics (5-25 mm) and macroplastics (25-100 mm), discovering elevated levels along the high salt marsh strandline compared to low salt marsh and mudflat areas. Notably, the abundance of plastic reached staggering levels, reaching up to 20,060 items/m2 in the vicinity of an illegal dumpsite. Microplastics, particularly in the 2-4 mm range, were dominant, and the main plastic components were high-density polyethylene (HDPE), low-density polyethylene (LDPE), polypropylene (PP), and polystyrene (PS). Plastic films emerged as the predominant plastic type, while the presence of pellets hinted at potential sources such as illegal dumping and port-related activities. This contamination could be largely attributed to inappropriate waste management practices and urban runoff, which pose a substantial ecological threat to these ecosystems. Urgent remedial action is essential to protect these marshes, underscoring the critical need for comprehensive wetland management and educational initiatives to ensure their long-term sustainability.

Long-term investigation of microplastic abundance in Squalius species in Turkish inland waters

Examining the enduring alterations in microplastic (MP) concentrations within fish in inland waters is of utmost importance in understanding the historical trajectory of plastic waste and formulating consequential predictions regarding upcoming pollution levels. This study includes the collection of fish samples from 22 different river basins in Türkiye and all Squalius species distributed in Türkiye, covering the years 2004-2018, and examined the presence of MP in museum specimens' gastrointestinal tracts (GITs). 331 specimens were examined, and microplastic was observed in 20.8% (69). A mean value of 0.27 ± 0.19 MP per individual was observed, resulting in a cumulative score of 91 MP. Most observed MPs were composed of fiber, representing 79.1% of the total. The polymer types identified were mostly polyethylene (PE) at 38.5% and polyethylene terephthalate (PET) at 29.7%. The black color was prominent among MPs, and MP length ranged between 101 and 4963 μm. The analysis revealed no statistically significant difference in the mean MP values across different years and basins. There is no substantial correlation between the abundance of MP and the sizes of fish, population density, or quantities of plastic production. The data indicate that MP has persistently acted as a contaminant in freshwater ecosystems over an extended period. It is projected that the laundering of synthetic textiles serves as the primary contributor to MP contamination in freshwater bodies. Our results offer significant baseline data on the pervasive issue of MP pollution in the freshwater environment. These findings enable us to gain profound insights into the current state of MP contamination in fish residing in lotic systems while empowering us to make accurate predictions about its future trajectory.

Temporal trends in personal protective equipment (PPE) debris during the COVID-19 pandemic in Çanakkale (Turkey)

This study examines trends in PPE (masks, gloves) and disinfecting wipes over three years of the pandemic. The densities of discarded masks, wet wipes, and gloves (personal protective equipment: PPE), were quantified on the streets of Canakkale, Turkey during similar time periods in 2020, 2021 and 2022. Geotagged images of PPE on the streets and sidewalks were documented with a smartphone, while the track of an observer was recorded using a fitness tracker app along a 7.777 km long survey route in the city center, parallel to the Dardanelles Strait. A total of 18 surveys were conducted over three years, and the survey route was subdivided into three zones based on utilization patterns: pedestrian zone, traffic zone and a recreational park zone. The combined densities of all types of PPE density were high in 2020, lower in 2021 and highest in 2022. The within year trend showed an increase over the three study years. The average density of gloves declined from an initially high level in 2020, when the SARS-CoV-2 virus was thought to be transmitted by contact, to near zero in 2021 and to zero in 2022. Densities of wipes were similar in 2020 and 2021 and higher in 2022. Masks were initially difficult to procure in 2020, and their densities progressively increased during that year reaching a plateau in 2021 with similar densities in 2022. PPE densities were significantly lower in the pedestrian route relative to the traffic and park routes, which were not different from each other. The partial curfews implemented by the Turkish government and the effects of prevention measures taken on the PPE concentration in the streets are discussed along with the importance of waste management practices.

Size-selective microplastic uptake by freshwater organisms: Fish, mussel, and zooplankton

Microplastics, as an emergent pollutant, have garnered substantial attention within aquatic environments, yet a significant knowledge gap persists regarding the interplay of organism size and pollution impacts on microplastic uptake in freshwater ecosystems. The main aim of the current study is to assess the microplastic ingestion by aquatic organisms across diverse trophic levels. To achieve this objective, zooplankton, mussels (Anodonta anatina), and fish (Carassius gibelio) were collected from the highly polluted Susurluk River Basin in Türkiye. The size distribution encompassed 160.8 ± 56.9 μm for the prevailing zooplankton, 6.9 ± 2.2 cm for mussel, and 20.4 ± 3.1 cm for fish, respectively. While no microplastic ingestion was observed among zooplankton, the finding highlights the influence of body-size and pollution on microplastic ingestion. In contrast, A. anatina and C. gibelio contained 617 and 792 microplastic particles, respectively. Predominantly, fibers emerged as the most prevalent microplastic type across trophic levels (except zooplankton) followed by films. Notably, only fish exhibited fragments within their gastrointestinal tract. A substantial correlation emerged between microplastic abundance and mussel size and weight, but no such correlation manifested for fish. The study also revealed a positive link between microplastic count and turbidity (phosphate and high Chl a level), impacting mussel ingestion capacity due to the variability in the food availability and potential shifts in feeding preferences. Conversely, no distinct pattern emerged for fish concerning water quality parameters and ingested microplastics. Consequently, our study underscores diverse microplastic uptake patterns in freshwater ecosystems, with a predominant frequency of microplastics falling with the 0.3 mm-3.0 mm range, emphasizing the significance of size-selective uptake by organisms.

Spatiotemporal distribution of microplastics in true frogs (Ranidae:Pelophylax) populations from Türkiye

Microplastics (MPs), which are of increasing concern in almost all ecosystems, continue to be an environmental threat. In the present study, the presence of MPs is investigated by using the gastrointestinal tracts (GITs) obtained from the true frog individuals sampled in the past years. The sample consists of a total of 146 individuals obtained from various regions of Türkiye. The results show that MPs were found in 87 adult frog individuals. The most predominant shape of MPs found was fiber, with a predominance of transparent color, and ethylene-vinyl acetate (EVA) was also the most abundant microplastic material. The highest amount of MPs among adult frog populations were found in the Denizli province. The size of MPs ranged between a minimum of 66 and a maximum of 3770 μm. In addition, no relationship was found between the body length and weight of the frogs and the sizes of MPs. Historically, most MPs were found in samples from 1990 and the highest content in terms of both color and material was detected in 1990. MPs were detected in almost all the years studied, but microplastic abundance varied from year to year. These results can be explained by the number of samples, habitat, and feeding behavior of adult frogs.

Marine plastic pollution in Morocco: state of the knowledge on origin, occurrence, fate, and management

Plastic pollution presents a major challenge facing stakeholders and decision-making worldwide. Plastics in the ocean damage biodiversity and marine ecosystem services that the blue economy relies upon. The present work analyses and reviews the literature on plastic pollution and the background knowledge about marine plastic pollution in Morocco. The economy of Morocco depends mainly on marine activities, including fisheries, tourism, and maritime trade. These sectors were identified as the main in-situ sources of plastics entering Moroccan coastal waters. The analysis results showed that the increasing abundance of plastics in such marine systems causes substantial economic loss to blue economy activities. In contrast, the lack of data on the plastic waste quantity entering Moroccan water is a limiting factor for assessing plastic pollution. This highlights the need for a risk assessment and more field investigations to value the weight impacts of marine activities generators of plastics on biodiversity and the economy. In addition, implementing laws and rules forbidding the disposal of plastic waste (PW) in public spaces, mainly beaches, and streets, is urgently needed. Raising awareness of plastic waste management and prioritizing improved waste collection, sorting, and management would boost Morocco's establishment and adoption of circular economy strategies. It is worth noting that while implementing the management projects and regulatory frameworks of plastic waste, considering their source and usage purpose is mandatory.

Microplastic ingestion by invasive Prussian carp (Carassius gibelio) used in fishmeal production in Türkiye

MP contamination in the gastrointestinal tract (GIT) of Prussian carp (Carassius gibelio) used in fishmeal production was examined. The samples were collected from Balık Lake, Karaboğaz Lake, and Liman Lake located in Kızılırmak Delta, Türkiye. The overall average abundance was 3.20±0.18 MP per fish and 0.036±0.002 MP per g. No significant correlation was determined between the MP abundance in the fish, fish length, and fish weight. The polymers were composed of 56.91% PET, 25.20% PP, 9.76% PE, and 8.13% PA. The determined shapes were fiber (78.0%), fragment (13.46%), and film (8.54%). The size ranged between 112 and 4775 μm with an average of 1341.41±66.07 μm. Depending on the occurrence frequency and abundance, it can be concluded that Carassius gibelio can be considered a MP vector in fishmeal. The results provide an essential baseline for future MP studies on the potential effects of MPs on aquatic organisms, fate, and impact on the fishmeal production process, aquaculture practices, and human health.

Microplastic pollution in two remote rivers of Türkiye

Microplastic pollution in aquatic ecosystems presents an emerging environmental threat that can have adverse effects on ecology, endanger aquatic species, and result in economic damage. Despite the numerous studies reporting the presence of microplastics in marine environments, research into their presence in freshwater systems or inland waters remains limited. This study aimed to assess the level of microplastic pollution transported by the Munzur and Pülümür Rivers and some small rivers that flow into the Uzunçayır dam lake, which is the confluence of the Munzur and Pülümür Rivers in Türkiye. Samples were collected from 23 stations, with the concentration of microplastics ranging from 0.01 MP/m³ at P-4 station to 28.21 MP/m³ at P-10, a station located near a city. Microplastics comprise four types: fiber, film, fragment, and glitter. The average size of microplastics was 1.46 ± 0.05 mm, with the average size of fibers, films, fragments, and glitter-type microplastics being 1.58 ± 0.07 mm, 1.23 ± 0.10 mm, 1.21 ± 0.11 mm, and 0.78 ± 0.16 mm, respectively. The most frequent polymers were polyethylene (31.8%), polystyrene (21.1%), and polypropylene (10.5%). Despite being considered remote and less populated rivers compared to other river systems in Türkiye, all sampling sites showed varying concentrations of microplastics.

From source to sink: A comparative study of streamside and beach litter in the Black Sea

The increasing amount of marine litter pollution and its impact on the marine environment raises global concern. This study aims to reveal the effect of streams on marine litter density and composition. A total of ten stations on the southeastern Black Sea and six stations on the Manahoz stream were seasonally surveyed. The litter density ranged between 0.838 ± 0.33 and 4.01 ± 0.55 items/m² in the beach stations, and 0.93 ± 0.27 2.40 ± 2.18 items/m² in the streamside stations. No significant difference was determined among the seasons for both beach and streamside (Kruskal-Wallis test, p > 0.05). On the other hand, the litter density was also similar in beach and streamside stations in the same season. The litter composition consisted of > 75% plastic. Principal component analysis and PERMANOVA determined no significant difference in litter composition among beach and streamside stations. The litter items mostly consisted of single-use items. Among them, plastic beverage containers were the most abundant litter subcategory during the study (ranging between 18.79% and 34.50%). The subcategory composition exhibited a significant difference among beach and streamside stations (ANOSIM, p < 0.05), which was mainly explained by plastic pieces, beverage containers, and foams according to SIMPER analysis. Personal protection equipment that was not reported before the COVID-19 pandemic emerged. The results of our study can be used for marine litter modeling studies and legislation for restriction or ban of most abundant single-use litter items.

Solid waste composition and COVID-19-induced changes in an inland water ecosystem in Turkey

The composition and abundance of solid waste and the effect of COVID-19 measures were studied in an inland water ecosystem in Turkey. Solid waste items were collected annually for 5 years from 2017 to 2021 from seven stations located in Borçka Dam Lake (B1-B4) and Murgul Stream (M1-M3) in the Artvin Province. The highest densities by number and weight were recorded at M3 in 2020 (5.72 items/m²) and M1 in 2020 (0.39 kg/m²), respectively. However, no significant difference in density was recorded (p < 0.05) between the years. Plastic was the most abundant waste material by number of items in all the stations with a percentage contribution varying between 25.47 and 88.89%. There was a considerable increase in medical items during the COVID-19 pandemic in 2020-2021. Nonmetric multidimensional scaling (NMDS) and ANOSIM results revealed visually and statistically significant differences in solid waste composition between the years and stations. The dissimilarity between the years was driven by plastic and medical waste. The main sources of solid waste were river transportation (22.93%), improper disposal (20.74%), aquaculture activities (16.42%), and recreational and tourism activities (14.72%). The results of our study can be a baseline for transportation models, local administrations, and non-governmental organizations. Besides, the current waste management measures in Turkey are not effective in preventing waste accumulation in inland aquatic systems such as the Borçka Dam Lake and Murgul Stream. Furthermore, these findings indicate that the COVID-19 pandemic influenced solid waste composition and increased its abundance in the study area.

Solid waste composition and COVID-19-induced changes in an inland water ecosystem in Turkey

The composition and abundance of solid waste and the effect of COVID-19 measures were studied in an inland water ecosystem in Turkey. Solid waste items were collected annually for 5 years from 2017 to 2021 from seven stations located in Borçka Dam Lake (B1-B4) and Murgul Stream (M1-M3) in the Artvin Province. The highest densities by number and weight were recorded at M3 in 2020 (5.72 items/m²) and M1 in 2020 (0.39 kg/m²), respectively. However, no significant difference in density was recorded (p < 0.05) between the years. Plastic was the most abundant waste material by number of items in all the stations with a percentage contribution varying between 25.47 and 88.89%. There was a considerable increase in medical items during the COVID-19 pandemic in 2020-2021. Nonmetric multidimensional scaling (NMDS) and ANOSIM results revealed visually and statistically significant differences in solid waste composition between the years and stations. The dissimilarity between the years was driven by plastic and medical waste. The main sources of solid waste were river transportation (22.93%), improper disposal (20.74%), aquaculture activities (16.42%), and recreational and tourism activities (14.72%). The results of our study can be a baseline for transportation models, local administrations, and non-governmental organizations. Besides, the current waste management measures in Turkey are not effective in preventing waste accumulation in inland aquatic systems such as the Borçka Dam Lake and Murgul Stream. Furthermore, these findings indicate that the COVID-19 pandemic influenced solid waste composition and increased its abundance in the study area.