Secondary microplastics were prevalent in sediment in a freshwater UK urban river

Abstract

29 30Plastic pollution has been documented in terrestrial and aquatic environments worldwide, with 31 growing concern for 'microplastics' (MPs, <5 mm). Understanding of the sources, fate, and impact of 32MPs remains limited, particularly in freshwater environments. Furthermore, their small sizes and a 33 lack of standardised methodology hinders monitoring and risk assessment of these emerging 34 contaminants. Here, the distribution of microscopic debris in an urban river close to the marine 35 environment in the West of Scotland was investigated to assess the prevalence of MPs. Bank sediment 36 samples were collected twice from the River Kelvin in Glasgow and were size-fractionated and 37 processed for extraction of MPs by density separation. Light microscopy and scanning electron 38 microscopy with energy dispersive spectroscopy, were employed for characterisation and 39 quantification of microdebris of sizes ranging from 2.8 mm to 0.45 µm. Sample MP spiking and use 40 of procedural blanks allowed the influence of processing on field data quality to be considered. The 41 predominant type of MPs were fibres, comprising >88% of total MP counts, but fibre content in 42 blanks suggested potential contributions from background contamination. Final MP abundances were 43 estimated at 161-432 items per kg dry sediment. In addition, metallic and glass pellets were observed 44 in high abundances in settled material and could be easily misidentified by visual inspection. Thus, 45 compositional analysis is needed to avoid analytical errors from MP misidentification and 46 overestimation. 47 48

Unveiling the noxious effect of polystyrene microplastics in aquatic ecosystems and their toxicological behavior on fishes and microalgae

“…The study revealed that the number of MPs found in the surface water of the river in the Tibet Plateau ranged from 483 to 967 items per cubic meter, whereas the amount found in the sediment ranged from 50 to 195 pieces per kilogram (Jiang et al, 2019). Meanwhile, another study that investigated the amount and distribution of primary and secondary MPs in an urban river near the coastal environment in the West of Scotland found that 88% of the overall counts comprised the major fiber type, which ranged from 161 to 432 MPs kg −1 dry sediment (Blair et al, 2019). However, the presence of fibers in the blanks suggests that air contamination may have played a role.…”

“…Even in rural or urban areas, Tibet Plateau had undeniably been tainted with MPs (Jiang et al, 2019). Subsequently, a few studies confirmed that MPs were coming from developed areas with intense human activities and remote areas (Blair et al, 2019;Anak Alexander Tampang and Mohan Viswanathan, 2022).…”

“…The characteristics of the sample can be gleaned from the information on the elements and their spatial distribution as provided by the instruments. For understanding the accumulation, impact, and other factors affected by MP, Blair et al (2019) used SEM analysis to evaluate the character and quantification of MPs. MPs from bank sediment samples at River Kelvin in Glasgow were sizefractionated: thus ranging from 2.8 mm to 11 m in diameter.…”

Microplastics: Global occurrence, impact, characteristics and sorting

“…Hence, for sampling and data collection, vessels of diverse speeds, dimensions, and types are used. Virginia and North Carolina, USA 596-2,224 particles/kg (Dodson et al, 2020) Kelvin River, UK 161-432 items/kg of dry sediment (Blair et al, 2019) Tributaries of Thames River Basin, UK 88-1,190 items/100 g of dry sediment (Lots et al, 2027) Edgbaston Pool, England 26 particles/100 g of dried sediment (Vaughan et al, 2022) Deerness Sound, Orkney, Scotland 5.65 ± 0.55 number of MPs/kg of sediment (Jones et al, 2020) Irish Continental Shelf 7.67 ± 2.09 and 6.33 ± 4.91 MPs/m 3 (Martin et al, 2017) Italy, France, Turkey, Greece, Israel, Bosnia, Portugal, Norway, Denmark, Sweden, Netherlands 72 ± 24 to 1512 ± 187 particles/kg of dry sediment (Lots et al, 2017) Lake Mjøsa and Lake Femunden, Norway 7.31 and 3.89 MPs/g (Lusher et al, 2018) Southern North Sea, Europe 421 particles/kg dry weight of sediment (Maes et al, 2017) River Elbe, Germany 3.35 × 10 6 ± 6.60 × 10 6 particles/m 3 (Scherer et al, 2020) Netherlands and Germany 100-2,071/kg dry weight of sediment (Leslie et al, 2017) Antuã River, Portugal 100-629 items/kg in March and from 18 to 514 items/kg in October (Rodrigues et al, 2018) Eastern Mediterranean, Lebanon 2,433 ± 2,000 MPs/kg d.w of sediment (Kazour et al, 2019) Lagoon-Channel of Bizerte, Northern Tunisia 7.96 ± 6.84 articles/g dry sediment (Abidli et al, 2017) Southeastern coastlines, South Africa 688.9 ± 348.2 particles/m 2 to 3,308 ± 1449 particles/m 2 (Nel et al, 2015) Baltic Sea, Russia 34 ± 10 items/kg dw of sediment (Zobkov and Esiukova, 2017) Mumbai, India 68.83 items/m 2 (194.33 ± 46.32 items/m 2 ) (Jayasiri et al, 2013) Maharashtra, Goa, and Karnataka, India 43.6 ± 1.1 to 346 ± 2 items/m 2 (Maharana et al, 2020) Chennai, Tuticorin, Tiruchenthur, Manapad, and Kanyakumari, India 439 ± 172 to 119 ± 72 items/kg in high tide; 179 ± 68 to 33 ± 30 items/kg in low tide (Sathish et al, 2019) Kanyakumari, India 43 particles/50 g dry sediment (Sundar et al, 2020) Mumbai, Dhanushkodi, and Tuticorin, India 45 ± 12 to 181 ± 60 items/kg (Tiwari et al, 2019) Nallathanni Island, Gulf of Munnar Biosphere Reserve, India NA (Krishnakumar et al, 2018) Nethravathi River, India Sediment: 96 pieces/kg Soil: 84.45 pieces/kg (Amrutha and Warrier, 2020) Sabarmati River, Gujrat, India 47.1 mg (MP in size range 75-212 µm) to 4 mg (MP in size range 212 µm...…”

Microplastics in sediments of the Pantanal Wetlands, Brazil

“…Studies of microplastics in sediments of freshwater environments have indicated that microplastics can be very abundant in urban rivers with high human population density and large commercial and industrial areas (Shruti et al, 2019;He et al, 2020). Microplastics found in these sediments are mainly of secondary origin, arising from the fragmentation of larger plastics or fibers from synthetic clothes washing (Blair et al, 2019). In Amazonian rivers in Brazil, for example, fiber microplastics predominated, especially in the vicinity of the city of urban areas (Gerolin et al, 2020).…”