Microplastics in rivers along an urban-rural gradient in an urban agglomeration: Correlation with land use, potential sources and pathways

Kunz, Alexander; Schneider, Falk; Anthony, Nixon; Lin, Hsin-Tien

doi:10.1016/j.envpol.2023.121096

Cited by 59 publications

(20 citation statements)

References 57 publications

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“…We did not observe a significant relationship between microplastic density and percent urbanization. This finding contrasts with other studies that found higher microplastic concentrations in aquatic ecosystems with increased urban land use (Kunz et al, 2023;Tanentzap et al, 2021;Townsend et al, 2019). However, in our study, the contribution of urban land use was low even at the most urbanized sites making it difficult for our results to be compared with other studies that investigated urban contribution to microplastic pollution within highly industrialized urban areas.…”

Section: Comparison With Other Studiescontrasting

confidence: 99%

Widespread microplastic pollution in Indiana, USA, rivers

Conard,

O'Reilly,

Hartlage

et al. 2023

River Research & Apps

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Microplastics (i.e., plastic particles <5 mm in size) are aquatic contaminants of emerging concern but are poorly quantified in flowing waters of the midwestern USA. Microplastics enter streams and rivers through a variety of pathways (e.g., wastewater effluent, breakdown of larger plastic debris, atmospheric deposition) and can potentially harm aquatic organisms through both direct consumption and indirect contamination from sorbed toxins. In this study, we quantified microplastic concentrations and types (i.e., beads, fibers, films, foams, fragments) in nine Indiana watersheds representing a gradient of dominant land use (i.e., agricultural, urban, and forested). We predicted that microplastic concentration would be higher in watersheds with higher percentages of urban and agricultural land use than in forested watersheds. Our results revealed measurable quantities of microplastics in samples from all watersheds, but microplastic concentration did not vary significantly with land use or longitudinally within watersheds. Fibers were the dominant form of microplastic at all sites, suggesting that fibers may be transported primarily through atmospheric deposition rather than via direct runoff from the surrounding landscape. We conclude that rivers have a different microplastic “signature” than large lakes, likely due to retention characteristics of flowing water ecosystems, unique microplastic sources, and a shorter legacy of microplastic pollution.

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Section: Comparison With Other Studiescontrasting

confidence: 99%

Widespread microplastic pollution in Indiana, USA, rivers

Conard,

O'Reilly,

Hartlage

et al. 2023

River Research & Apps

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“…Inadequate disposal of single-use plastics and daily wear and tear of dishwashing sponges, particularly from residential areas, can introduce various coloured MPs into the soil. Residential areas are recognised as the primary source of MPs(Kunz et al, 2023).Although our research did not nd a signi cant relationship between soil texture and the occurrence of MPs, studies byYang et al (2023) andYu et al (2021) have reported that MPs are more prevalent in loamy sand or sandy loam soils. Loamy sand and sand textures are typically gritty and loose with high drainage and low organic matter content(Rashid et al, 2021).…”

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confidence: 83%

“…For example, Y. discovered a positive correlation between construction areas and MP abundance. Similarly, a clear prevalence of higher MP concentrations has been found in industrial, commercial, residential(Kunz et al, 2023), and heavy-tra c areas(Fan et al, 2024). The city of Thimphu has witnessed a signi cant rise in dwelling density, as well as increased construction and demolition activities.…”

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confidence: 99%

Microplastic pollution in riparian soils of the rapidly growing city of Thimphu, Bhutan

Jamtsho,

Lund,

Blake

et al. 2024

Preprint

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Plastic has become a vitally important material for humans; however, the large amount of plastic waste generated annually pollutes the environment. Plastic decomposition generates microplastics (MPs), which have emerged as a concerning global environmental pollutant because of their potential to be more harmful to the environment than their larger counterparts. This study investigated the effects of land use, distance to impervious cover (IC), and plot IC% on the abundance of MPs, as well as the relationship between MPs and urban riparian soil (RS) properties, surface plastic, textile waste, and distance to upstream drainage outlet in the riparian zone (RZ) of the Wang River in Thimphu City, Bhutan. A density separation technique was used to extract MPs from the soil. The results showed that RS in urban sites had higher concentrations of MPs (93.31%) than in other land use (7.69%, p = 0.04). Blue MPs (46.15%) were the most common plastic colour. MPs in urban RS sites were distributed unevenly, ranging from 0 to 500 particles/kg. MP concentration was positively correlated with RS available phosphorus (p = 0.01). Our findings highlight the nature and pathways of MP pollution in developing cities, where the emphasis on economic growth often leads to environmental management being deprioritized. We also identify opportunities for developing cities to reduce MP pollution by recovering surface plastic and textile waste, recycling, and disposing of them in low-impact landfills.

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“…Sources of MPs include littering, open dumps, improperly managed landfills, atmospheric deposition, runoff from roads, agriculture, and settlements ( de Souza Machado et al, 2018 ; Horton et al, 2017 ), as well as from fishing gears ( Ruangpanupan et al, 2022 ) and plastic bags used in checkdam construction. Animals may ingest PE, PP, and PET from plastic bags, bottles, ropes, or fishing gears, commonly used in packaging ( Wang, Zhao & Xing, 2021 ) and are prevalent in daily items ( Liu et al, 2020 ), especially in Thailand ( ONEP, 2023 ), and are frequently encountered in urban-rural gradients ( Kunz et al, 2023 ), including our study area. PE and PP might be released from personal care products containing microbeads ( Napper et al, 2015 ) and fishing gears ( Chinfak et al, 2021 ).…”

Section: Discussionmentioning

confidence: 99%

Terrestrial wildlife as indicators of microplastic pollution in western Thailand

Teampanpong,

Duengkae

2024

PeerJ

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Plastic pollution in terrestrial wildlife represents a new conservation challenge, with research in this area, especially within protected areas (PAs), being scant. This study documents the accumulation of microplastics (MPs) in terrestrial wildlife both inside and outside PAs in western Thailand. Carcasses of road-killed vertebrates in good condition, as well as live tadpoles, were collected to examine their exposure to plastic pollution. The digestive tracts of the vertebrate carcasses and the entire bodies of tadpoles were analyzed for MPs, which were identified if they measured over 50 µm. A total of 136 individuals from 48 vertebrate species were examined. The sample comprised snakes (44.12%), birds (11.03%), lizards (5.15%), tadpoles (32.25%), amphibians (5.88%), and mammals (1.47%). In total, 387 MPs were found in 44 species (91.67%), with an average occurrence of 3.25 ± 3.63 MPs per individual or 0.05 ± 0.08 MPs per gram of body weight. The quantities of MPs significantly varied among the animal groups, both in terms of number per individual (p < 0.05) and number per gram of body weight (p < 0.01). Furthermore, a significant difference in MP quantities was observed between specimens collected inside and outside PAs on an individual basis (p < 0.05), but not on a body weight basis (p = 0.07). Most MPs were fibers (77%), followed by fragments (22.22%), with only a minimal presence of film (0.52%) and foam (0.26%). Of all the MPs identified, 36.84% were confirmed as plastics or fibers made from natural materials, and 31.58% were plastics, including Polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP), Polyvinylidene chloride (PVDC), and polyester (PES). Additionally, fibers made of cotton, and those containing polyurethane (PU), rayon, PES, and combinations of rayon and PU, were identified. The quantities of MPs were significantly influenced by animal body weight, factors associated with human settlement/activity, and land use types. Our findings highlight the prevalence of plastic pollution in terrestrial vertebrates within Thai PAs. Further toxicological studies are required to establish plastic pollution standards. It is proposed that snakes, obtained from road kills, could serve as a non-invasive method for monitoring plastic pollution, thus acting as an indicator of the pollution threat to species within terrestrial ecosystems. There is an urgent need for the standardization of solid waste management at garbage dump sites in remote areas, especially within PAs. Conservation education focusing on MP occurrence, potential sources, and impacts could enhance awareness, thereby influencing changes in behaviors and attitudes toward plastic waste management at the household level.

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Microplastics in rivers along an urban-rural gradient in an urban agglomeration: Correlation with land use, potential sources and pathways

Cited by 59 publications

References 57 publications

Widespread microplastic pollution in Indiana, USA, rivers

Widespread microplastic pollution in Indiana, USA, rivers

Microplastic pollution in riparian soils of the rapidly growing city of Thimphu, Bhutan

Terrestrial wildlife as indicators of microplastic pollution in western Thailand

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