Microplastics in river sediments in two streams in an Andean region of Peru

Microplásticos em sedimentos fluviais de dois córregos em uma região andina do Peru

ABSTRACT

The objective of this study was to determine the concentration, types and characteristics (size, morphology and color, as well as polymer composition) of MPs in surface sediments in two streams in an Andean region of Peru. Surface sediment samples were collected in Ishoj stream (11 sampling sites) and Uyru Rume stream (8 sampling sites), and density separation was performed using high-density saline solution (zinc chloride, ZnCl₂) to separate the MPs from the sediment. The concentration of MPs ranged from 0 - 2216 items/Kg (Ishoj stream) and 0 - 6383 items/Kg (Uyru Rume stream). In both streams, the maximum concentration of MPs was in the sites located near the dumps (solid waste collection, downstream) and the minimum value was found in the sites located in the upper zone. The size, morphology and predominant color in both streams were less than 1 mm, fragment and transparent, respectively. No MPs were found in pellet form. PP (polypropylene) was the predominant MPs in Raman analysis. All MPs were secondary. This study report contamination by MPs in streams in Andean zones.

Keywords:
Dumps; Fragment; Intermittent streams; Madeán; Polypropylene

RESUMO

O objetivo deste estudo foi determinar a abundância, tipos e características (tamanho, morfologia e cor) de Microplásticos (MPs) em sedimentos superficiais em dois riachos em uma região andina do Peru. Amostras de sedimentos superficiais foram coletadas no riacho Ishoj (11 locais de amostragem) e no riacho Uyru Rume (8 locais de amostragem), e a separação por densidade foi realizada usando solução salina de alta densidade (cloreto de zinco, ZnCl₂) para separar os MPs do sedimento. A abundância de MPs variou de 0 a 2.216 itens/Kg (córrego Ishoj) e 0 a 6.383 itens/Kg (córrego Uyru Rume). Em ambos os córregos, a concentração máxima de MPs foi nos locais localizados próximos aos lixões (coleta de resíduos sólidos, a jusante) e o valor mínimo foi encontrado nos locais localizados na zona alta. O tamanho, morfologia e cor predominante em ambos os riachos foram inferiores a 1 mm, fragmentados e transparentes, respectivamente. Nenhum MP foi encontrado em forma de pellet. PP (polipropileno) foi o MP predominante na análise Raman. Todos os MP eram secundários. Este estudo relata contaminação por MPs em riachos em zonas andinas.

Palavras-chave:
Lixões; Fragmentados; Fluxos intermitentes; Madeán; polipropileno

INTRODUCTION

In 1950, around 2 million tons (t) of plastics were produced in the world and in 2017, 348 million tons were produced (Geyer, 2020), increasing notably over this time interval. As a result of this production, it is estimated that by 2050, there will be more plastic than fish in the ocean (by weight) (World Economic Forum, 2016), and that there will be 12 billion metric tons of plastic in landfills or in the global environment (Geyer et al., 2017). Similarly, in Peru in 2020, about 8 million t of municipal solid waste were generated (Perú, 2020), of which plastic represents 10.1% of the total (Perú, 2012), with 4.8% being recycled. Of the percentage of municipal waste, 52.8% goes to a landfill, and the rest is discarded into the environment (41.9% in illegal dumps, 0.4% is burned and 0.1% other final destination of the waste) (Instituto Nacional de Estadística e Informática, 2018b). Plastic pollution has effects on the environment that range from entanglement and increased mortality in some aquatic species to alteration of the physical habitat (Welden & Lusher, 2020). The longevity of plastic ranges from hundreds to thousands of years, which of concern considering that the mass production of plastics began less than 60 years ago (Barnes et al., 2009). Plastic introduced to the environment remains unmineralized, whole or in fragments (microplastics, MPs) (Thompson et al., 2005).

In recent decades, MPs (particles > 1 micron and < 5 mm) (Carpenter & Smith Junior, 1972) have been found in the environment and are considered modern pollution. This type of pollution is omnipresent (Rochman, 2018) and has increased exponentially in recent years. The concentration of MPs is of special concern (Lamichhane et al., 2023) due to their small size and the potential for environmental dispersal (Horton et al., 2016), leading to publications about MPs in the environment (Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection, 2015; Van Cauwenberghe et al., 2015) due to important magnitude of the problem (Ghosh et al., 2023).

The sources of MPs may be primary, which are manufactured plastics of microscopic size for direct use, such as plastic pellets, industrial abrasives, exfoliants and others; and secondary MPs, which are fragments derived from larger plastic material (Welden & Lusher, 2020; Borriello et al., 2023). The latter fragment in the environment due to exposure to the elements and as a consequence of biodegradation, photodegradation, thermo-oxidative degradation and hydrolysis, as well as abrasion due to the action of water (Barnes et al., 2009).

Therefore, by persisting as MPs in the environment, living beings may ingest them, transfer them to other levels of the food chain, or interact in the incorporation of other pollutants and provide a new habitat in the aquatic environment (Ghosh et al., 2023). MPs in the environment are not only composed of structural polymers, but are considered pollution cocktails, due to the sorption of external contaminants (outside the particle) and leaching from the MP of chemical substances (additives) such as: flame retardants, colorants, biocides, plasticizers and others (interior of the particle) (Vethaak & Leslie, 2016; Castañeda et al., 2020), since these are bound to the polymer matrix only by Van Der Waals force (weak force) and can, therefore, be released into the surrounding medium (Zimmermann et al., 2020).

MPs adsorb polycyclic aromatic hydrocarbons (Ogata et al., 2009; Noro & Yabuki, 2021). For example, plastic resin granules have been found to adsorb organic compounds in marine environments (Fu et al., 2021; Santana-Viera et al., 2021). According to the Stockholm Convention, MPs can adsorb persistent organic pollutants, which are organic compounds that are persistent in the environment and bioaccumulative (Stockholm Convention UNEP, 2018). In addition, it has been detected that plastic granules collected on the beaches of England contain adsorbed variable concentrations of trace metals (Cr, Co, Ni, Cu, Zn, Cd and Pb), with plastics being a vehicle for the transport of metals in aquatic systems (Liu et al., 2022). Therefore, plastics with environmental contaminants can be transported to organisms at various trophic levels (Haque & Fan, 2023).

The final disposal of solid waste including plastics is a problem, because it is carried out in dumps located in streams and their riverbeds (Perú, 2004; Caicedo-Concha et al., 2021), as in the case of the town of Madeán, in which studies on waste composition (Canchari & Iannacone, 2021) and photographic evidence of dumps with waste (Figure 1) have demonstrated the presence of plastics. Specifically, macroplastics (2.5 cm<) (Van Cauwenberghe et al., 2015), such as bags, bottles, food wrappers, cutlery, plastic cups and others have been identified (Lahens et al., 2018). A certain amount of plastic breaks down to MPs in river environments before entering the ocean (Kataoka et al., 2018), making freshwater ecosystems sinks for plastic particles (Xu et al., 2020) and a significant emission pathway for MPs from land to the ocean due to fluvial transport (Wijnen et al., 2019). Therefore, the concentrations of MPs in a river depend on the activities of the population in the river basin (Kataoka et al., 2018), and it is of special concern that plastic fragments are probably decreasing in size in the environment, increasing the concentration and global distribution of MPs in recent years (Barnes et al., 2009). The concentration of MPs is associated with population density (Shruti et al., 2019) and dumps are considered a potential source of MPs (He et al., 2019b).

Figure 1
Sampling sites in intermittent streams.

To our knowledge, there are only a few studies on MPS in the Andean Rivers (Canchari & Iannacone, 2023) and this is the first study to investigate the presence of MPs in intermittent streams close to populated areas in the Cañete River Basin. Therefore, the objective of this study was to determine the concentration, types and characteristics of MPs in surface sediments in the two intermittent streams adjacent to the town of Madeán, Peru.

MATERIALS AND METHODS

Study area

The populated center of Madeán (district capital of Madeán, province of Yauyos, department of Lima) with Universal Transverse Mercator (UTM) coordinates WGS84 -18L of 8568874.271 m S; 415,687.108 m E at 3,275 meters above sea level (Perú, 1965; Flores & Changanaqui, 2019), and 223 inhabitants according to the 2017 last National Census (Instituto Nacional de Estadística e Informática, 2018a). Today, the final disposal sites for plastic waste, including single-use waste, were open-air dumps (100%) (a 90% was burned) and also dumped in dumps (10%) in the two streams (Ishoj and Uyru Rume) surrounding the town of Madeán (Figure 1). In addition, these two streams are tributaries (Figure 1) of the Huangáscar River and are located in the Huangáscar sub-basin (belonging to the Cañete River basin) (Autoridad Nacional del Agua, 2019). The activation of the Ishoj and Uyru Rume intermittent stream occurs in the precipitation season from October to April (Agencia de Cooperación Internacional del Japón, 2012). According to the National Water Authority (Autoridad Nacional del Agua, 2019), the Huangáscar sub-basin has higher rainfall between January and March, with an average annual rainfall of 642.2 mm. In addition, the waste in the dumps is exposed to solar radiation (Figure 1). The Huangascar River, belonging to the Cañete River, presents native fish such as Trichomycterus rivulatus, Orestias agassii and O. hardini in shallow environments with abundant vegetation, and the exotic species Oncorhynchus mykiss, which can be consumed by local human populations (Perú, 2011). The map was made with ARCMAP and the graphics were made in Power BI.

Ishoj Stream (Q1)

This intermittent stream is located on the eastern side of the populated center of Madeán, with the peripheral neighborhood of Viscaya located in the upper part. It is the longest intermittent stream, with approximately 3118 m (Figure 1) and higher flow of 0 to 200 l/s compared to the Uyru Rume stream of 0 to 5 l/s. The stream comprises the UTM coordinates WGS84 -18L from 8569688.628 m S; 415804.311 m E to 8567128.513 m S; 415071.513 m E.

Uyru Rume Stream (Q2)

This intermittent stream is located on the west side of the town center of Madeán (Organismo de Evaluación y Fiscalización Ambiental, 2021). with approximately 1456 m. This stream covers the UTM coordinates WGS84 -18L from 8569547.471 m S; 415064.765m E to 8568235.599m S; 415062.042 m E.

Selection of Sampling Sites

Sediment samples were collected in the two streams located on the east and west sides of the town center of Madeán in April during the stream activation season. Upstream and downstream sampling sites were selected with reference to dumps and populated centers. Previous visual observations had revealed that there was evidence of remains of plastic waste deposited in dumps in each stream (Figure 1).

Sampling sites selection and sampling procedures

Sediment samples were collected at 11 and 8 sampling sites along the intermittent Ishoj (Q1) and Uyru Rume (Q2) streams, respectively (Figure 1). The number of samples in each stream were selected based on accessibility (Shruti et al., 2019), the accumulation of surface sediments, and the length of the streams. The geographical coordinates, meters above sea level and distance between samples sites are indicated in Table 1.

Table 1
geographical coordinates, meters above sea level and distance between samples sites of intermittent streams.

Geographical Coordinates
Sampling sites	Longitude (W)	Latitude (S)	meters above sea level	Distance from Q1/2-1 (m)
Q1-1	75°46'34.33"	12°56'13.57"	2929	0
Q1-2	75°46'31.11"	12°56'23.22"	3062	320
Q1-3	75°46'29.50"	12°56'29.38"	3140	525
Q1-4	75°46'31.64"	12°56'35.26"	3233	729
Q1-5	75°46'31.69"	12°56'38.97"	3244	871
Q1-6	75°46'31.70"	12°56'42.19"	3265	986
Q1-7	75°46'35.13"	12°56'46.45"	3285	1158
Q1-8	75°46'36.55"	12°56'56.28"	3350	1472
Q1-9	75°46'43.79"	12°57'16.63"	3530	2176
Q1-10	75°46'58.39"	12°57'26.22"	3546	2793
Q1-11	75°46'52.64"	12°57'35.22"	3558	2879
Q2-1	75°46'58.67"	12°56'18.45"	2865	0
Q2-2	75°46'59.01"	12°56'21.57"	2911	100
Q2-3	75°46'57.41"	12°56'28.90"	3069	342
Q2-4	75°46'57.12"	12°56'33.13"	3145	479
Q2-5	75°46'57.63"	12°56'36.62"	3182	594
Q2-6	75°46'58.71"	12°56'40.42"	3229	720
Q2-7	75°46'58.41"	12°56'41.33"	3235	750
Q2-8	75°47'3.19"	12°56'52.74"	3379	1148

The sediment sample was collected in an area between the shoreline and the water's edge (Jiang et al., 2019). At each site, three sediment samples were randomly selected at a depth of 2 cm, using a metal frame with dimensions of 20 x 20 cm and a height of 2 cm (Wang et al., 2017) and a stainless steel shovel (Horton et al., 2016). Then, these sediments were placed together in an aluminum foil bag as a single mixture (Wang et al., 2017) and transported to the laboratory of the Universidad Nacional Federico Villarreal, at the Laboratorio de Ecología y Biodiversidad Animal (LEBA).

Samples treatment

The three sediment samples of each site were dried at 50 °C for at least 48 h and 30 g of each sample was investigated (Wang et al., 2017). The separation of MPs was performed according to the modified density separation method of Thompson et al., (2004), using a high density (1.7 g cm^-3) zinc chloride solution (ZnCl₂) (Imhof et al., 2012) for the isolation of MPs in sediments, since it guarantees the separation of all types of MPs (Imhof et al., 2012; Horton et al., 2016). Including MP particles with high densities, such as polyvinyl chloride (PVC) (1.14–1.56 g.mL^-1) and polyethylene terephthalate (PET) (1.32–1.41 g.mL^-1) (Nuelle et al., 2014 ; Xu et al., 2020), which according to Plastic Europe represent > 17% of the global demand for plastic (Quinn et al., 2017).

Subsamples were weighed and placed in a beaker and 30 ml of 30% H₂O₂ was added and left overnight to remove natural organic remains. Then, 36 ml of the solution previously prepared with 1.8 Kg of ZnCl₂ dissolved in one liter of distilled water (Imhof et al., 2012; Horton et al., 2016) was added.

After 24 h, the supernatant was filtered through 6 μm filter paper with a vacuum pump (Shruti et al., 2019). Lastly, filtered water was added to the walls of the filtration device and the washing solutions were also filtered. Filter paper containing MPs was stored in Petri dishes and dried at 50 °C for 48 hours in the laboratory (Wang et al., 2017; Shruti et al., 2019).

Each filter was reviewed and the MPs contained were counted using a microscope. The average of the counts of the 3 subsamples were calculated and for each sample, and the results are expressed in items.Kg ^-1 of dry sediment (Lin et al., 2018; Jiang et al., 2019).

Concentration of MPs

Under the microscope, the characteristics of MPs such as size, morphology and color were determined. Sizes were measured using a measuring ruler attached to the lens. Sizes were classified measuring the longest axis as <0.5 mm (up to 6 µm), 0.5-1 mm, 1-2 mm, 2-3 mm, 3-4 mm, and 4-5 mm (Jiang et al., 2019). The morphology was identified and classified as fiber (strand or filament of plastic), pellet (spherical or cylindrical figure of plastic), film (a thin sheet of plastic), fragment (irregular and/or hard piece of plastic, broken from a larger plastic) and foam (piece of sponge or foam) (Crawford & Quinn, 2016), with the modification that each morphology comprises sizes less than 5 mm. To avoid confounding synthetic fibers with cotton fibers, the criteria of Norén (2007) and practical experience (Song et al., 2015) were followed. The colors were classified based on the color of the dominant surface, which could be green, transparent, blue, yellow, black, red and white (Su et al., 2016; Lin et al., 2018). Finally, the chemical characterization was determined by Raman spectroscopy (Imhof et al., 2012; Horton et al., 2016).

MPs of different colors, morphologies and sizes were selected from both streams. All MPs from all points were placed in a 1500mm x 25mm glass petri dish with a filter paper and 17 samples of MPs were selected, considering that they included all representative shapes, colors and sizes of MPs (Huang et al., 2023). These were sent to the laboratory of the Materials Characterization Center of the Pontificia Universidad Católica del Perú (CAM-PUCP) for their respective analysis.

Finally, in order to get photographs of MPs were used an image processing software (ImageJ, downloaded from http://imagej.nih.gov) (Kataoka et al., 2018).

Contamination prevention

To prevent the samples from being contaminated by plastic products (Li et al., 2020), the following measures were followed:

In the field

A stainless steel paddle (Horton et al., 2016) was used to collect the samples, which was then placed in aluminum foil bags on site (Wang et al., 2017). Additionally, cotton gloves were used (Shruti et al., 2019). Likewise, blank controls were carried out at each sampling site. A clean Petri dish with a moistened membrane filter was placed in the soil to consider air pollution by MPs (Lin et al., 2018). In addition, the stainless steel frame and paddle were washed before sampling each sampling site.

In laboratory

Vessels used were rinsed three times with filtered water, and the saline solution was filtered before use (filter porosity 0.45 microns). Laboratory windows were closed at the time of the experiment. Nitrile gloves (Iannacone et al., 2021) were used. All samples were covered with aluminum foil at all times during the experiment. Additionally, to take into account possible air contamination, three control samples of ZnCl₂ solution with a volume equivalent to the filtrate per field sample were analyzed (Horton et al., 2016) and a clean Petri dish with a filter was placed on a moistened membrane.

Statistical analysis

Statistical analyzes were performed with the Statistical Package for Social Sciences (SPSS) (Li et al., 2020). A Shapiro-Wilk test indicated that MP concentration data were not normally distributed, therefore nonparametric tests were used. The Kruskal-Wallis test was performed and the Games-Howell Post Hoc test was used to determine the difference between sites. The statistical test was performed separately for each stream. To compare the concentration between streams and to compare the concentration between sampling sites located below the dumps with those above, the Mann Whitney U test was used. It was considered significantly different when the p value was less than 0.05 (Xu et al., 2020).

RESULTS AND DISCUSSION

Concentration of MPs in the two intermittent streams

Our investigation showed the presence of contamination by MPs (n = 14412) in the two intermittent streams Q1 (Ishoj stream) (n = 5628 MPs, 39.05%) y Q2 (Uyru Rume Stream) (n= 8784 MPs, 60.95%). Q2 is an intermittent stream with less waste deposition than Q1 (Figure 1). Both the Ishoj and Uyru Rume streams have pockets in which waste has been deposited (including plastics) (sampling sites Q1 and Q2, respectively). This was confirmed by the presence of MPs in most of the sampling sites, except for sites Q1-11 (Ishoj stream) and Q2-8 (Uyru Rume stream), which were far from a populated center or a dump (Table 2 and Figure 1). MP Concentrations of MPs in rivers differed between the water and sediment phase. Sediment concentrations are a long-term key sinks for MPs, and were in average higher than water concentrations (Scherer et al., 2020; Zhang et al., 2020). However, the residues deposited in the intermittent stream channels could be displaced when reached by the water level (Kataoka et al., 2018).

Table 2
Concentration of microplastics by sampling site in the Ishoj and Uyru Rume streams (letters indicate statistical differences).

Zone	Sampling sites		MPs (Items/Kg)	± Standard Deviation
Ishoj Stream (Q1)	Q1-1	bcdf	556	51
	Q1-2	bcf	633	33
	Q1-3	a	1278	117
	Q1-4	bdf	389	19
	Q1-5	a	2217	217
	Q1-6	ef	33	0
	Q1-7	bcdef	333	88
	Q1-8	ef	89	19
	Q1-9	ef	100	33
	Q1-10	ef	67	33
	Q1-11		BDL*	BDL
Uyru Rume Stream (Q2)	Q2-1	C	400	57
	Q2-2	C	456	38
	Q2-3	C	422	51
	Q2-4	C	400	33
	Q2-5	B	667	33
	Q2-6	A	6383	217
	Q2-7	D	56	19
	Q2-8		BDL*	BDL

• ^*
  = below detection limits (BDL) for the protocol you used.

Taking this into account, it is likely that the dumps located in stream beds are the main potential sources of MPs in intermittent streams. In the dry sediment samples analyzed at the Ishoj stream sites, the highest MPs concentration was 2217± 217 items/kg. The highest concentration was in the Q1-5 site. In the Uyru Rume stream sites, MPs were found ranging from 56 – 6383 items/kg. The highest concentration of MPs in the two streams was found at sites Q1-5 (Ishoj stream) and Q2-6 (Uyru Rume stream) (Table 2), which are close to the dump areas (Figure 1) (Perú, 2004). In addition, from the point at which the dump is located, the sites located downstream of the dump at Q1-5 had generally higher concentrations of MPs compared to the upper part of the stream (the statistical test shows the differences). Also, there must be MPs contributed from the Ishoj river basin and even from smaller intermittent affluent that are very important to consider to explain the variations of MPs between different points. Other possibly is that MPs is being transported from the river basins when it rains or by wind from another basin. In addition, some accumulated vegetation that temporarily dams the water and allow MPs to settle when the river is running (Yang et al., 2021). Other factors that affect the abundance of MPs in river sediments include sediment particle size, population density near water catchment, proximity to urban centers, water flow velocity, land use, water catchment size, type of waste management used, and sewage spillage (He et al., 2020; Yang et al., 2021). The highest concentration was at site Q2-6, compared to the data shown. As can be seen in Table 2, in most other studies regarding river sediments, the concentration of MPs found in this study were higher than that reported in sediments of the Thames River in the United Kingdom (UK) (Horton et al., 2016), Antuã River, Portugal (Rodrigues et al., 2018), the River Tame, UK (Tibbetts et al., 2018), Brisbane River, Australia (He et al., 2019a), the rivers of the Tibet plateau, China (Jiang et al., 2019), of the Zahuapan and Atoyac rivers, Mexico (Shruti et al., 2019), the Solimões and Amazon Rivers in Brazil (Gerolin et al., 2020), the Daliao and Shuangtaizi Rivers, China (Xu et al., 2020); and less than the Wen-Rui Tang river basin in China (Wang et al., 2018), and the Negro river in Brazil (Gerolin et al., 2020) which shows that most rivers have a lower MP concentrations in sediments compared to the streams studied (Table 3). It is therefore likely that the intermittent streams surrounding populated centers have high concentrations of MPs, with an increase in the concentration of MPs with the urbanization and population density (Kataoka et al. 2018).

Table 3
Comparison of the concentration of microplastics of the present study with select 14 articles in the world.

water fountain system	Location	Concentration (items/Kg)	Salt	Range (µm)	Reference
Thames River	United Kingdom	185 - 660	ZnCl2	1000 -4000	Horton et al. (2016)
Ottawa River	Canada	Maximum = 450	NaCl	100-5000	Vermaire et al. (2017)
Beijiang river	China	178 - 544	NaCl	1 - 5000	Wang et al. (2017)
Antua River	Portugal	18 -629	ZnCl2	55 - 5000	Rodrigues et al. (2018)
River tame	United Kingdom	20 - 350	ZnCl2	63 - 4000	Tibbetts et al. (2018)
Wen-Rui Tang River Basin	China	18690 - 74800	ZnCl2	0.4 - 5000	Wang et al, (2018)
Rivers of the Tibetan Plateau	China	50 - 195	ZnCl2	0.22-5000	Jiang et al. (2019)
Brisbane river	Australia	10 -520	ZnCl2	0.45 - 5000	He et al. (2019a)
Jequtepeque River Basin	Peru	0-90	NaCl	180 - 500	Manrique (2019)
Zahuapan and Atoyac River	Mexico	66.67 - 400; 100 - 400	ZnCl2	1.2 -5000	Shruti et al. (2019)
Qin river	China	0 - 97	NaCl	0.45 - 5000	Zhang et al. (2019)
Rio Negro, Solimões and Amazonas	Brazil	5869-8178; 1524 - 1738; 417 - 2101	ZnCl2	63 - 5000	Gerolin et al. (2020)
Daliao River and Shuangtaizi	China	100-467; 133 -300	ZnCl2	5 -5000	Xu et al. (2020)
Ishoj and Uyru Rume Stream	Peru	0 - 2216; 0 - 6383	ZnCl2	6- 5000	present study

Table 3 shows MPs concentrations in sediments from studies that used the same separation salt solution (Zinc chloride, ZnCl₂) compared to studies using NaCl (sodium chloride) as a reference (Nuelle et al., 2014; Xu et al., 2020). In the present study it was used ZnCl₂ saline solution as a separation salt solution, that has a high density and therefore allows a best separation of high-density MPs in comparison to NaCl (Nuelle et al., 2014; Xu et al., 2020). Large MPs (LMPs) (1-5mm) and small MPs (SMPs) (<1mm) were recovered from plastic types such as polyamide (PA), polyethylene (PE), PVC, polycarbonates (PC), high-density polyethylene (HDPE), PET and polypropylene (PP) (Imhof et al., 2012). Therefore, the type of the saline solution influences the obtaining of MPs (Shruti et al., 2019), and according to the density affects the flotation process, and, it is possible that not all types of MPs would have been determined.

The concentration of MPs may have been higher considering that a fraction of MPs might not have been detected when using a pore size of 6 µm in the filtration process, making the concentration of MPs between 1 µm and less than 6 µm uncertain. In the same way, Table 3 shows studies with different minimum detectable sizes, with some not considering 1 µm as the minimum value, thereby making it important to mention the minimum MP size detectable.

Taking into account that the quality of MPs results depends on the sampling methodology and its processing in the laboratory (Adomat & Grischek, 2021). In the present study, surface sediment sampling was carried out on the shore, providing a large area for sampling and being profitable due to the use of simple tools (shovel or spoon). In addition, among the studies reviewed, the digestion most commonly used was H₂O₂ (Adomat & Grischek, 2021), as in our study. Likewise, in our study ZnCl₂ was used. This high-density saline solution allows the separation of high-density MPs (Nuelle et al., 2014).

There was a significant difference in the concentration of MPs per sampling site in the two streams (p<0.05). Means that do not share a common letter are significantly different (p<0.05).

MPs characteristics

Some of the MPs detected on 4 sandy beaches in Peru (Purca & Henostroza, 2017) could have originated from populated centers, since according to Wijnen et al. (2019) they reach the oceans through fluvial transport. They could also come from local pollution close to the beaches. Therefore, the discussion involves the fluvial and marine system.

MPs size in intermittent streams

In our investigation, MPs smaller than 1 mm (SMP) which includes the ranges < 0.5 mm and 0.5 to 1 mm (n = 8994, 58.67%) in proportion of size of MPs represented the predominant size in both streams (Figure 2). These results coincide with more than 70% found in sediments in the rivers of the Tibet Plateau, China (Jiang et al., 2019), in the Tame River in the UK (Tibbetts et al., 2018), in the Wen-Rui Tang river basin (Wang et al., 2018) and in the Negro and Solimõe rivers of Brazil (Gerolin et al., 2020).

Figure 2
Concentration of MPs of different size per sampling site. Q1-5, Q1-6, and Q2-7 sites are close to dumps in the streams bed.

In addition, in terms of the percentage of total sizes of MPs for each stream, it was noted in both streams that the larger the size > 1 mm of the MP (n = 5983, 41.33%), the lower its concentration (Gerolin et al., 2020). However, the toxicity of MPs on the biota depends mainly on their size, rather than their composition (Cole et al., 2013; Wright et al., 2013; Lei et al., 2018; Nelms et al., 2018).

In this study, LMP (1-5 mm) were also found. Thus, depending on the size of the organism either SMP or LMP may be ingested. Indeed, according to Boerger et al. (2010), the most common plastic size class ingested by 670 fish of six species was LMP of 1 to 2.79 mm (50%), and the average number of plastic pieces ingested increased as the size of the fish increased. On the other hand, in 630 clams (Corbicula fluminea), SMPs of 0.025 - 1 mm in size (55%) were the most commonly ingested (Su et al., 2018). Intermittent streams used as dumps are likely sources of MPs that could affect native fish such as T. rivulatus, O. agassii and O. hardini, and the exotic species O. mykiss in the Huangascar River belonging to the Cañete River (Perú, 2011).

MPs morphology in intermittent streams

In the Ishoj and Uyru Rume streams, among the total MPs found in each stream, fragments (n = 7843, 54.18%), and fibers (n=4098, 28.32%) were predominant, followed by film (n= 2385, 16.47%) and foam (n= 150, 1.04%), except for foam in the Uyru Rume stream, which was not found at any sampling site (Figure 3 and Figure 4). The results suggest that macroplastics had not been dumped in the form of foam in that stream, but dumps are not the only sources of MPs in Q1, and it is likely that MPs accumulates in areas of the basin during dry spells, and when rain begins, these can be transported to the canal where they can deposit depending on the hydraulics of the stream (He et al., 2020; Yang et al., 2021). These forms of MPs are derived from larger plastic materials, with these MPs being secondary MPs. For example, fragments are from solid waste (larger plastics) (Derraik, 2002; Jiang et al., 2019), while films are more likely from the breakage of plastic bags and packaging materials (Zhang et al., 2015), and fibers come from detachment from synthetic clothes (Jiang et al., 2019) and foam is likely due to breakage of polystyrene foam (disposable plates and cups) (Nuelle et al., 2014). The forms of MPs are a concern, since freshwater ecosystems are a significant emission pathway for MPs from land to the ocean through fluvial transport (Wijnen et al., 2019). Indeed, in the fish evaluated it was found that they had ingested plastic in the form of fragments (94% of the total MPs) (Boerger et al., 2010). In addition, only fibers were found in the gills of all the fish evaluated and sold in Lima (Iannacone et al., 2021). MPs in the form of fibers were also found predominantly in clams (Su et al., 2018). Films were found in the digestive tract of shrimp sold in supermarkets in Singapore, with their consumption having implications for human health and food safety (Curren et al., 2020). Micro-sized styrofoam particles were identified in mussels, with hazardous additives (hexabromocyclododecane, HBCDs) attached to the styrofoam being transferred to mussels by ingestion or by water seepage (Jang et al., 2016). In the Huangascar River, the fish T. rivulatus, O. agassii, O. hardini and O. mykiss could be consuming fragments and fibers of MPs. These freshwater fish can be consumed by nearby human populations.

Figure 3
Photographs of microplastics using an optical microscope: foam (a and b), fiber (c), film (dye) and fragment (f, g, h, i, j, k, and l).

Figure 4
Concentration of MPs of different morphology by sampling site.

The presence of MP fragments was the predominant form in this study similar to what was described in the River Tame (Tibbetts et al., 2018), the Wen-Rui Tang River basin (Wang et al., 2018) and different from what was found in the Tang River basin. In the Atoyac River films predominate (Shruti et al., 2019), while in the rivers of the Tibet Plateau, fibers predominate (Jiang et al., 2019).

Pellets were not found in any of the sample sites (Figure 4), as in the case of other studies that analyzed fluvial sediments in which MPs were found (Jiang et al., 2019; Shruti et al., 2019; Xu et al., 2020). For example, possible sources of pellets are plastic manufacturers, domestic and industrial effluent discharge (Shruti et al., 2019). However, in the populated center studied there is no record of any industry (Instituto Nacional de Estadística e Informática, 2012). This likely explains why no pellets were found at any sampling site.

In addition, the fragments (Figure 3f and 3g) clearly showed cracks in the entire area of both MPs, with these two being PP-type MPs identified by Raman analysis. What is likely is that PP fragments into smaller particles more easily compared to PE (Xiong et al., 2018). In addition, exposure to ultraviolet radiation followed by mechanical abrasion results in a high generation of MPs from PP compared to PE (Song et al., 2017).

Color of MPs in intermittent streams

Transparent (n= 5423, 37.46%), blue (n=2767, 19.11%), black (n= 1803, 12.45%), red (n= 1354, 9.35%), white (n=1443, 9.97), green (n=1304, 9.01%) and yellow (n=383, 2.65%) MPs were identified. Of the total MPs identified in each stream, the transparent MPs predominated in both intermittent streams (Figure 5). These results are similar to those found in sediments in the rivers of the Tibetan Plateau (Jiang et al., 2019). The transparent color was also the most frequently observed in the Negro and Amazon rivers (Gerolin et al., 2020). The proportion of transparent plastics fragment produced was higher with respect to that of other colors (Jiang et al., 2019). Transparent MPs can originate from cellophane, single-use plastics, plastic bags and others. In addition, white MPs can be made from bottles with caps, disposable spoons and forks, and ice cream cups, among others. The other colors of MPs can originate from the fragmentation of containers, toys, household products, bags, plastic straw and food wrappers (Osorio et al., 2021).

Figure 5
Concentration of MPs of different color by sampling site.

Regarding the ingestion of colored MPs, zooplankton-feeding fish may mistakenly feed on MPs with white, brown, and yellow colors that resemble their prey (Shaw & Day, 1994). Another study reported that the colors of plastics ingested by fish were predominantly white, transparent and blue (87% in total), being colors that are similar to the plankton of the area that are food (Boerger et al., 2010). Another alarming case is the study by Iannacone et al. (2021), which found MPs in 100% of the fish evaluated for economic importance and sold in Lima, with predominant colors in the following order: blue, black, white, fuchsia and green. In addition, blue and transparent MPs were found among the most abundant in clams compared to other colors (Su et al., 2018).

Polymer composition

Only 17 MPs were analyzed with Raman spectroscopy. PE, PP, PS, and PET were identified by Raman spectroscopy. These thermoplastic polymers as well as PVC, are the most commonly found in MPs (Andrady, 2017), with the world market being dominated by these classes of plastics (Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection, 2015).

High-density polymers such as PET and PBT polyester are higher than the density of NaCl. Table 2 shows some studies that used this saline solution. In addition, the PP, PE, PA and PS polymers without additives have densities lower than 1.2 g.mL^-1, but with additives, the density increases (US EPA, 1998) making it necessary to use more effective high-density salt solutions as ZnCl₂ (Rodrigues et al., 2020) the density of which is greater, allowing the separation of MP particles with high densities, such as PVC (1.14–1.56 g .mL^-1), PET (1.32–1.41 g.mL^-1) (Nuelle et al., 2014; Xu et al., 2020) and low-density MPs (without additives) which acquire high densities with additives.

According to the results of the Raman analysis PP and PE were the most abundant plastics (Figure 6). The types of polymers identified by Raman analysis are related to the fact that during the sampling in both streams in our investigation, plastic bags, discarded PET bottles and textile waste were found, possibly being transported from the river basins when it rains or by wind from other basin. According to Díaz et al. (2020), in Peru 50.1 thousand tons of rigid PET containers have been dumped in dumps or in the environment. Therefore, what is mentioned in this research is related to the PET bottles found in the streams. Furthermore, an expected polymer, nylon (PA), was observed here. As well as PBT polyester.

Figure 6
Types of microplastics (n=17). Numbers of microplastics particles (%).

Therefore, MPs cannot be treated in the same way when evaluating environmental hazards, owing to different types of plastics, different chemical composition and physical characteristics (Zimmermann et al., 2020). It is important to understand the concentration, types and characteristics of MPs to adequately assess environmental hazards. In addition, the results of this study provide evidence that intermittent streams are sources of MPs for the main rivers. However, In Q1 and Q2, the concentration of MPs encountered close to the perennial river was less than what is found in sites near the dumps. It seems that this decrease in concentration indicates that most MPs are retained in the intermittent stream basin and are not transported to the perennial river that could eventually transport these to the ocean. It even seems that do not travel far in both of the studied streams if it considered the amazing drop in concentration between Q1-5 (dump) and Q1-4 (less than 200 m downriver).

CONCLUSIONS

It is concluded that high concentrations of MPs, in both intermittent streams in an Andean river occurs in dump sites (considered areas of high concentrations of MPs). In both streams, there was a higher concentration of MPs downstream compared to the area above the dump.

The predominant MPs found in both streams in the present study ranged from less than 1 mm in size, were fragments and fibers morphology, and also were transparent in color. There was no evidence of presence of pellets at any sampling site. The MPs in this study are considered secondary MPs.

The concentration of PP and PE MPs types were dominant in both streams, and to a lesser extent other MPs (PBT, PA, PET and PS), indicating that most of the plastic materials used by inhabitants of the populated center and discarded in the streams correspond to these types of MPs.

ACKNOWLEDGEMENTS

This study was carried out thanks to the partial support (Raman analysis of MPs) from the District Municipality of Madeán (Mayor Aníbal Díaz Reynoso and aldermen). To the LEBA laboratory (Laboratory de Ecología y Biodiversidad Animal), Facultad de Ciencias Naturales y Matemática de la Universidad Nacional Federico Villarreal (UNFV) for providing the facilities to carry out the experiment. We also the families for the moral support at all times.

REFERENCES

• Adomat, Y., & Grischek, T. (2021). Sampling and processing methods of microplastics in river sediments - A review. The Science of the Total Environment, 758, 143691. http://doi.org/10.1016/j.scitotenv.2020.143691
  » http://doi.org/10.1016/j.scitotenv.2020.143691
• Agencia de Cooperación Internacional del Japón – ACIJ. (2012). Hidrología de máximas avenidas del río Cañete Retrieved in 2024, March 2, from https://openjicareport.jica.go.jp/pdf/12125233_02.pdf
  » https://openjicareport.jica.go.jp/pdf/12125233_02.pdf
• Andrady, A. (2017). The plastic in microplastics: A review. Marine Pollution Bulletin, 119(1), 12-22. http://doi.org/10.1016/j.marpolbul.2017.01.082
  » http://doi.org/10.1016/j.marpolbul.2017.01.082
• Autoridad Nacional del Agua – ANA. (2019). Estudio hidrológico de la unidad hidrográfica Cañete Retrieved in 2024, March 2, from https://repositorio.ana.gob.pe/handle/20.500.12543/4713
  » https://repositorio.ana.gob.pe/handle/20.500.12543/4713
• Barnes, D., Galgani, F., Thompson, R., & Barlaz, M. (2009). Accumulation and fragmentation of plastic debris in global environments. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences, 364(1526), 1985-1998. http://doi.org/10.1098/rstb.2008.0205
  » http://doi.org/10.1098/rstb.2008.0205
• Boerger, C., Lattin, G., Moore, S., & Moore, C. (2010). Plastic ingestion by planktivorous fishes in the North Pacific Central Gyre. Marine Pollution Bulletin, 60(12), 2275-2278. http://doi.org/10.1016/j.marpolbul.2010.08.007
  » http://doi.org/10.1016/j.marpolbul.2010.08.007
• Borriello, L., Scivicco, M., Cacciola, N. A., Esposito, F., Severino, L., & Cirillo, T. (2023). Microplastics, a global issue: human exposure through environmental and dietary sources. Foods, 12(18), 3396. http://doi.org/10.3390/foods12183396
  » http://doi.org/10.3390/foods12183396
• Caicedo-Concha, D. M., Sandoval-Cobo, J. J., Stringfellow, A., & Colmenares-Quintero, R. F. (2021). An evaluation of final disposal alternatives for municipal solid waste through life cycle assessment: a case of study in Colombia. Cogent Engineering, 8(1), 1956860. http://doi.org/10.1080/23311916.2021.1956860
  » http://doi.org/10.1080/23311916.2021.1956860
• Canchari, F., & Iannacone, J. (2021). Residuos sólidos municipales en el centro poblado de Madeán, distrito de Madeán, provincia de Yauyos, región Lima, Perú en época de pandemia del COVID-19. Paideia XXI, 11(2), 11-25.
• Canchari, F., & Iannacone, J. (2023). Microplastics in sediments deposited by rainwater runoff in a populated center in the Peruvian Andes. RBRH, 28, e7. http://doi.org/10.1590/2318-0331.282320220108
  » http://doi.org/10.1590/2318-0331.282320220108
• Carpenter, E., & Smith Junior, K. (1972). Plastics on the Sargasso sea surface. Science, 175(4027), 1240-1241. http://doi.org/10.1126/science.175.4027.1240
  » http://doi.org/10.1126/science.175.4027.1240
• Castañeda, G., Gutiérrez, A., Nacaratte, F., & Manzano, C. (2020). Microplásticos: un contaminante que crece en todas las esferas ambientales, sus características y posibles riesgos para la salud pública por por exposición. Revista Boliviana de Química, 37(3), 160-175. http://doi.org/10.34098/2078-3949.37.3.4
  » http://doi.org/10.34098/2078-3949.37.3.4
• Cole, M., Lindeque, P., Fileman, E., Halsband, C., Goodhead, R., Moger, J., & Galloway, T. (2013). Microplastic ingestion by zooplankton. Environmental Science & Technology, 47(12), 6646-6655. http://doi.org/10.1021/es400663f
  » http://doi.org/10.1021/es400663f
• Crawford, C. B., & Quinn, B. (2016). Microplastic pollutants USA: Elsevier Science. http://doi.org/10.1016/C2015-0-04315-5
  » http://doi.org/10.1016/C2015-0-04315-5
• Curren, E., Leaw, C. P., Lim, P. T., & Leong, S. C. Y. (2020). Evidence of marine microplastics in commercially harvested seafood. Frontiers in Bioengineering and Biotechnology, 8, 562760. http://doi.org/10.3389/fbioe.2020.562760
  » http://doi.org/10.3389/fbioe.2020.562760
• Derraik, J. (2002). The pollution of the marine environment by plastic debris: a review. Marine Pollution Bulletin, 44(9), 842-852. http://doi.org/10.1016/S0025-326X(02)00220-5
  » http://doi.org/10.1016/S0025-326X(02)00220-5
• Díaz, R., Velarde, G., & Lino, G. (2020). Análisis de Flujo de Materiales de Plástico para la Producción, Consumo y Comercio de Envases Rígidos del Polietileno de Tereftalato (PET) en Perú durante 2018. La Saeta Universitaria Académica y de Investigación, 9(2), 15-38. Retrieved in 2024, March 2, from https://www.unae.edu.py/ojs/index.php/saetauniversitaria/article/view/238
  » https://www.unae.edu.py/ojs/index.php/saetauniversitaria/article/view/238
• Flores, R., & Changanaqui, M. (2019). Estudios y diseños del sistema de agua potable y alcantarillado para el centro poblado Madean, distrito de Madean, provincia de yauyos, región Lima Universidad José Faustino Sánchez Carrión. Retrieved in 2024, March 2, from renati.sunedu.gob.pe/handle/sunedu/1573839
  » renati.sunedu.gob.pe/handle/sunedu/1573839
• Fu, L., Li, J., Wang, G., Luan, Y., & Dai, W. (2021). Adsorption behavior of organic pollutants on microplastics. Ecotoxicology and Environmental Safety, 217, 112207. http://doi.org/10.1016/j.ecoenv.2021.112207
  » http://doi.org/10.1016/j.ecoenv.2021.112207
• Gerolin, C., Pumpin, F., Sawakuchi, A., Grohmann, C., Labuto, G., & Semensatto, D. (2020). Microplastics in sediments from Amazon rivers, Brazil. The Science of the Total Environment, 749, 141604. http://doi.org/10.1016/j.scitotenv.2020.141604
  » http://doi.org/10.1016/j.scitotenv.2020.141604
• Geyer, R. (2020). Production, use, and fate of synthetic polymers. In T. M. Letcher (Ed.), Plastic waste and recycling (Chap. 2, pp. 13-32). Cambridge: Academic Press. http://doi.org/10.1016/B978-0-12-817880-5.00002-5
  » http://doi.org/10.1016/B978-0-12-817880-5.00002-5
• Geyer, R., Jambeck, J., & Law, K. (2017). Production, use, and fate of all plastics ever made. Science Advances, 3(7), 1-5. http://doi.org/10.1126/sciadv.1700782
  » http://doi.org/10.1126/sciadv.1700782
• Ghosh, S., Sinha, J. K., Ghosh, S., Vashisth, K., Han, S., & Bhaskar, R. (2023). Microplastics as an emerging threat to the global environment and human health. Sustainability (Basel), 15(14), 10821. http://doi.org/10.3390/su151410821
  » http://doi.org/10.3390/su151410821
• Haque, F., & Fan, C. (2023). Fate and impacts of microplastics in the environment: hydrosphere, pedosphere, and atmosphere. Environments, 10(5), 70. http://doi.org/10.3390/environments10050070
  » http://doi.org/10.3390/environments10050070
• He, B., Goonetilleke, A., Ayoko, G., & Rintoul, L. (2019a). Abundance, distribution patterns, and identification of microplastics in Brisbane River sediments, Australia. The Science of the Total Environment, 700, 1-32. http://doi.org/10.1016/j.scitotenv.2019.01.329
  » http://doi.org/10.1016/j.scitotenv.2019.01.329
• He, P., Chen, L., Shao, L., Zhang, H., & Lü, F. (2019b). Municipal solid waste (MSW) landfill: a source of microplastics? -Evidence of microplastics in landfill leachate. Water Research, 159, 38-45. http://doi.org/10.1016/j.watres.2019.04.060
  » http://doi.org/10.1016/j.watres.2019.04.060
• He, B., Wijesiri, B., Ayoko, G. A., Egodawatta, P., Rintoul, L., & Goonetilleke, A. (2020). Influential factors on microplastics occurrence in river sediments. The Science of the Total Environment, 738, 139901. http://doi.org/10.1016/j.scitotenv.2020.139901
  » http://doi.org/10.1016/j.scitotenv.2020.139901
• Horton, A., Svendsen, C., Williams, R., Spurgeon, D., & Lahive, E. (2016). Large microplastic particles in sediments of tributaries of the River Thames, UK – Abundance, sources and methods for effective quantification. Marine Pollution Bulletin, 114, 218-226. http://doi.org/10.1016/j.marpolbul.2016.09.004
  » http://doi.org/10.1016/j.marpolbul.2016.09.004
• Huang, Z., Hu, B., & Wang, H. (2023). Analytical methods for microplastics in the environment: a review. Environmental Chemistry Letters, 21(1), 383-401. http://doi.org/10.1007/s10311-022-01525-7
  » http://doi.org/10.1007/s10311-022-01525-7
• Iannacone, J., Príncipe, F., Minaya, D., Panduro, G., Carhuapoma, M., & Alvariño, L. (2021). Microplásticos en peces marinos de importancia económica en Lima, Perú. Revista de Investigaciones Veterinarias del Perú, 32(2), e20038. http://doi.org/10.15381/rivep.v32i2.20038
  » http://doi.org/10.15381/rivep.v32i2.20038
• Imhof, H., Schmid, J., Niessner, R., Ivleva, N., & Laforsch, C. (2012). A novel, highly efficient method for the separation and quantification of plastic particles in sediments of aquatic environments. Limnology and Oceanography, Methods, 10(7), 524-537. http://doi.org/10.4319/lom.2012.10.524
  » http://doi.org/10.4319/lom.2012.10.524
• Instituto Nacional de Estadística e Informática – INEI. (2012). IV Censo nacional agropecuario 2012 Retrieved in 2024, March 2, from http://censos.inei.gob.pe/cenagro/tabulados/
  » http://censos.inei.gob.pe/cenagro/tabulados/
• Instituto Nacional de Estadística e Informática – INEI. (2018a). Directorio Nacional de Centros Poblados Censos Nacionales 2017: XII de población, VII de vivienda y III de comunidades indígenas Retrieved in 2024, March 2, from https://www.inei.gob.pe/media/MenuRecursivo/publicaciones_digitales/Est/Lib1541/tomo4.pdf
  » https://www.inei.gob.pe/media/MenuRecursivo/publicaciones_digitales/Est/Lib1541/tomo4.pdf
• Instituto Nacional de Estadística e Informática – INEI. (2018b). Perú: Indicadores de Gestión Municipal 2018 Retrieved in 2024, March 2, from https://www.inei.gob.pe/media/MenuRecursivo/publicaciones_digitales/Est/Lib1636/index.html
  » https://www.inei.gob.pe/media/MenuRecursivo/publicaciones_digitales/Est/Lib1636/index.html
• Jang, M., Shim, W. J., Han, G. M., Rani, M., Song, Y. K., & Hong, S. H. (2016). Styrofoam debris as a source of hazardous additives for marine organisms. Environmental Science & Technology, 50(10), 4951-4960. http://doi.org/10.1021/acs.est.5b05485
  » http://doi.org/10.1021/acs.est.5b05485
• Jiang, C., Yin, L., Li, Z., Wen, X., Luo, X., Hu, S., Yang, H., Long, Y., Deng, B., Huang, L., & Liu, Y. (2019). Microplastic pollution in the rivers of the Tibet Plateau. Environmental Pollution, 249, 91-98. http://doi.org/10.1016/j.envpol.2019.03.022
  » http://doi.org/10.1016/j.envpol.2019.03.022
• Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection – GESAMP. (2015). Source, fate and effects of microplastics in the marine environment: a global assessment (Rep. Stud. GESAMP, No. 90, 96 p ). London: IMO. Retrieved in 2024, March 2, from http://www.gesamp.org/publications/reports-and-studies-no-90
  » http://www.gesamp.org/publications/reports-and-studies-no-90
• Kataoka, T., Nihei, Y., Kudou, K., & Hinata, H. (2018). Assessment of the sources and inflow processes of microplastics in the river environments of Japan. Environmental Pollution, 244, 958-965. http://doi.org/10.1016/j.envpol.2018.10.111
  » http://doi.org/10.1016/j.envpol.2018.10.111
• Lahens, L., Strady, E., Kieu-Le, T.-C., Dris, R., Boukerma, K., Rinnert, E., Gaspery, J., & Tassin, B. (2018). Macroplastic and microplastic contamination assessment of a tropical river (Saigon River, Vietnam) transversed by a developing megacity. Environmental Pollution, 236, 661-671. http://doi.org/10.1016/j.envpol.2018.02.005
  » http://doi.org/10.1016/j.envpol.2018.02.005
• Lamichhane, G., Acharya, A., Marahatha, R., Modi, R. B., Paudel, R., Adhikari, A., Raut, B. K., Aryal, S., & Parajuli, N. (2023). Microplastics in environment: global concern, challenges, and controlling measures. International Journal of Environmental Science and Technology, 20(4), 4673-4694. http://doi.org/10.1007/s13762-022-04261-1
  » http://doi.org/10.1007/s13762-022-04261-1
• Lei, L., Wu, S., Lu, S., Liu, M., Song, Y., Fu, Z., Shi, H., Raley-Susma, K., & He, D. (2018). Microplastic particles cause intestinal damage and other adverse effects in zebrafish Danio rerio and nematode Caenorhabditis elegans. The Science of the Total Environment, 619-620, 1-8. http://doi.org/10.1016/j.scitotenv.2017.11.103
  » http://doi.org/10.1016/j.scitotenv.2017.11.103
• Li, Y., Lu, Z., Zheng, H., Wang, J., & Chen, C. (2020). Microplastics in surface water and sediments of Chongming Island in the Yangtze Estuary, China. Environmental Sciences Europe, 32(15), 1-12. http://doi.org/10.1186/s12302-020-0297-7
  » http://doi.org/10.1186/s12302-020-0297-7
• Lin, L., Zuo, L.-Z., Peng, J.-P., Cai, L.-Q., Fok, L., Yan, Y., Li, X.-X., & Xu, X.-R. (2018). Occurrence and distribution of microplastics in an urban river: A case study in the Pearl River along Guangzhou City, China. The Science of the Total Environment, 644, 375-381. http://doi.org/10.1016/j.scitotenv.2018.06.327
  » http://doi.org/10.1016/j.scitotenv.2018.06.327
• Liu, S., Huang, J., Zhang, W., Shi, L., Yi, K., Yu, H., Zhang, Ch., Li, S., & Li, J. (2022). Microplastics as a vehicle of heavy metals in aquatic environments: a review of adsorption factors, mechanisms, and biological effects. Journal of Environmental Management, 302, Pt A, 113995.
• Manrique, R. (2019). Microplásticos en sedimentos fluviales de la cuenca baja y desembocadura del río Jequetepeque, Perú Retrieved in 2024, March 2, from http://tesis.pucp.edu.pe/repositorio/handle/20.500.12404/15030
  » http://tesis.pucp.edu.pe/repositorio/handle/20.500.12404/15030
• Nelms, S., Galloway, T., Godley, B., Jarvis, D., & Lindeque, P. (2018). Investigating microplastic trophic transfer in marine top predators. Environmental Pollution, 238, 999-1007. http://doi.org/10.1016/j.envpol.2018.02.016
  » http://doi.org/10.1016/j.envpol.2018.02.016
• Norén, F. (2007). Small plastic particles in Coastal Swedish waters Retrieved in 2024, March 2, from https://www.n-research.se/pdf/Small plastic particles in Swedish West Coast Waters.pdf
  » https://www.n-research.se/pdf/Small
• Noro, K., & Yabuki, Y. (2021). Photolysis of polycyclic aromatic hydrocarbons adsorbed on polyethylene microplastics. Marine Pollution Bulletin, 169, 112561. http://doi.org/10.1016/j.marpolbul.2021.112561
  » http://doi.org/10.1016/j.marpolbul.2021.112561
• Nuelle, M., Dekiff, H., Remy, D., & Fries, E. (2014). A new analytical approach for monitoring microplastics in marine sediments. Environmental Pollution, 184, 161-169. http://doi.org/10.1016/j.envpol.2013.07.027
  » http://doi.org/10.1016/j.envpol.2013.07.027
• Ogata, Y., Takada, H., Mizukawa, K., Hirai, H., & Isawa, S. (2009). International Pellet Watch: global monitoring of persistent organic pollutants (POPs) in coastal waters. 1. Initial phase data on PCBs, DDTs, and HCHs. Marine Pollution Bulletin, 58(10), 1437-1446. http://doi.org/10.1016/j.marpolbul.2009.06.014
  » http://doi.org/10.1016/j.marpolbul.2009.06.014
• Organismo de Evaluación y Fiscalización Ambiental - OEFA. (2021). Áreas degradadas por Residuos Sólidos Retrieved in 2024, March 2, from https://pifa.oefa.gob.pe/AppResiduos/
  » https://pifa.oefa.gob.pe/AppResiduos/
• Osorio, E., Tanchuling, M., & Diola, M. B. (2021). Microplastics occurrence in surface waters and sediments in five river mouths of Manila Bay. Frontiers in Environmental Science, 9, 719274. http://doi.org/10.3389/fenvs.2021.719274
  » http://doi.org/10.3389/fenvs.2021.719274
• Perú. Congreso de la Republica Peruana. (1965). Ley n° 15478, Creando el Distrito de Madeán, en la provincia de Yauyos. Lima: El Peruano.
• Perú. Ministerio de Salud – Minsa. (2004). Guía técnica para la clausura y conversión de botaderos de residuos sólidos Retrieved in 2024, March 2, from http://bvs.minsa.gob.pe/local/MINSA/1650.pdf
  » http://bvs.minsa.gob.pe/local/MINSA/1650.pdf
• Perú. Ministerio del Ambiente – Minam. (2011). Inventario y evaluación del Patrimonio Natural en la Reserva Paisajística Nor Yauyos Cochas. Dirección General de Evaluación, Valoración y Financiamiento del Patrimonio Natural, Del Ministerio Del Ambiente. Retrieved in 2024, March 2, from https://www.minam.gob.pe/direccion/wp-content/uploads/sites/6/2013/09/patromonio-natural.pdf
  » https://www.minam.gob.pe/direccion/wp-content/uploads/sites/6/2013/09/patromonio-natural.pdf
• Perú. Ministerio del Ambiente – Minam. (2012). Informe anual de residuos sólidos municipales y no municipales en el Perú gestión 2012 Retrieved in 2024, March 2, from https://redrrss.minam.gob.pe/material/20140423145035.pdf
  » https://redrrss.minam.gob.pe/material/20140423145035.pdf
• Perú. Ministerio del Ambiente – Minam. (2020). Residuos. Generación total de residuos sólidos municipales Retrieved in 2024, March 2, from https://sinia.minam.gob.pe/informacion/tematicas?tematica=08
  » https://sinia.minam.gob.pe/informacion/tematicas?tematica=08
• Purca, S., & Henostroza, A. (2017). Presencia de microplásticos en cuatro playas arenosas de Perú. Revista Peruana de Biología, 24(1), 101-106. http://doi.org/10.15381/rpb.v24i1.12724
  » http://doi.org/10.15381/rpb.v24i1.12724
• Quinn, B., Murphy, F., & Ewins, C. (2017). Validation of density separation for the rapid recovery of microplastics from sediment. Analytical Methods, 9(9), 1491-1498. http://doi.org/10.1039/C6AY02542K
  » http://doi.org/10.1039/C6AY02542K
• Rochman, C. M. (2018). Microplastics research: from sink to source. Science, 360(6384), 28-29. http://doi.org/10.1126/science.aar7734
  » http://doi.org/10.1126/science.aar7734
• Rodrigues, M., Abrantes, N., Gonçalves, F., Nogueiraa, H., Marques, J., & Gonçalves, A. (2018). Spatial and temporal distribution of microplastics in water and sediments of a freshwater system (Antuã River, Portugal). The Science of the Total Environment, 633, 1549-1559. http://doi.org/10.1016/j.scitotenv.2018.03.233
  » http://doi.org/10.1016/j.scitotenv.2018.03.233
• Rodrigues, M., Gonçalves, A., Gonçalves, F., & Abrantes, N. (2020). Improving cost-efficiency for MPs density separation by zinc chloride reuse. MethodsX, 7, 100785. http://doi.org/10.1016/j.mex.2020.100785
  » http://doi.org/10.1016/j.mex.2020.100785
• Santana-Viera, S., Montesdeoca-Esponda, S., Guedes-Alonso, R., Sosa-Ferrera, Z., & Santana-Rodríguez, J. J. (2021). Organic pollutants adsorbed on microplastics: analytical methodologies and occurrence in oceans. Trends in Environmental Analytical Chemistry, 29, e00114. http://doi.org/10.1016/j.teac.2021.e00114
  » http://doi.org/10.1016/j.teac.2021.e00114
• Scherer, C., Weber, A., Stock, F., & Burusic, S. (2020). Comparative assessment of microplastics in water and sediment of a large European river. The Science of the Total Environment, 738, 139866. http://doi.org/10.1016/j.scitotenv.2020.139866
  » http://doi.org/10.1016/j.scitotenv.2020.139866
• Shaw, D., & Day, R. (1994). Colour- and form-dependent loss of plastic micro-debris from the North Pacific Ocean. Marine Pollution Bulletin, 28(1), 39-43. http://doi.org/10.1016/0025-326X(94)90184-8
  » http://doi.org/10.1016/0025-326X(94)90184-8
• Shruti, V., Jonathan, M., Rodríguez, P., & Rodríguez, F. (2019). Microplastics in freshwater sediments of Atoyac River basin, Puebla City, Mexico. The Science of the Total Environment, 654, 154-163. http://doi.org/10.1016/j.scitotenv.2018.11.054
  » http://doi.org/10.1016/j.scitotenv.2018.11.054
• Song, Y. K., Hong, S. H., Jang, M., Han, G. M., Jung, S. W., & Shim, W. J. (2017). Combined effects of UV exposure duration and mechanical abrasion on microplastic fragmentation by polymer type. Environmental Science & Technology, 51(8), 4368-4376. http://doi.org/10.1021/acs.est.6b06155
  » http://doi.org/10.1021/acs.est.6b06155
• Song, Y., Hong, S., Jang, M., Han, G., Rani, M., Lee, J., & Shim, W. (2015). A comparison of microscopic and spectroscopic identification methods for analysis of microplastics in environmental samples. Marine Pollution Bulletin, 93(1–2), 202-209. http://doi.org/10.1016/j.marpolbul.2015.01.015
  » http://doi.org/10.1016/j.marpolbul.2015.01.015
• Stockholm Convention UNEP. (2018). Marine plastic litter and microplastics. Stockholm Convention on Persistent Organic Pollutants Retrieved in 2024, March 2, from http://chm.pops.int/Implementation/Publications/BrochuresandLeaflets/tabid/3013/Default.aspx
  » http://chm.pops.int/Implementation/Publications/BrochuresandLeaflets/tabid/3013/Default.aspx
• Su, L., Cai, H., Kolandhasamy, P., Wu, C., Rochman, C., & Shi, H. (2018). Using the Asian clam as an indicator of microplastic pollution in freshwater ecosystems. Environmental Pollution, 234, 347-355. http://doi.org/10.1016/j.envpol.2017.11.075
  » http://doi.org/10.1016/j.envpol.2017.11.075
• Su, L., Xue, Y., Li, L., Yang, D., Kolandhasamy, P., Li, D., & Shi, H. (2016). Microplastics in Taihu Lake, China. Environmental Pollution, 216, 711-719. http://doi.org/10.1016/j.envpol.2016.06.036
  » http://doi.org/10.1016/j.envpol.2016.06.036
• Thompson, R., Moore, C., Andrady, A., Gregory, M., Takada, H., & Weisberg, S. (2005). New directions in plastic debris. Science, 310(5751), 1117. http://doi.org/10.1126/science.310.5751.1117b
  » http://doi.org/10.1126/science.310.5751.1117b
• Thompson, R., Olsen, Y., Mitchell, R., Davis, A., Rowland, S., John, A., McGonigle, D. & Rushell, A. (2004). Lost at sea: where is all the plastic? Science, 304(5672), 838. http://doi.org/10.1126/science.1094559
  » http://doi.org/10.1126/science.1094559
• Tibbetts, J., Krause, S., Lynch, I., & Sambrook, G. (2018). Abundance, distribution, and drivers of microplastic contamination in urban river environments. Water (Basel), 10(11), 1597. http://doi.org/10.3390/w10111597
  » http://doi.org/10.3390/w10111597
• US EPA. (1998). Plastic pellets in the aquatic environment sources and recommendations USA: US EPA.
• Van Cauwenberghe, L., Devriese, L., Galgani, F., Robbens, J., & Janssen, C. R. (2015). Microplastics in sediments: a review of techniques, occurrence and effects. Marine Environmental Research, 111, 5-17. http://doi.org/10.1016/j.marenvres.2015.06.007
  » http://doi.org/10.1016/j.marenvres.2015.06.007
• Vermaire, J., Pomeroy, C., Herczegh, S., Haggart, O., & Murphy, M. (2017). Microplastic abundance and distribution in the open water and sediment of the Ottawa River, Canada, and its tributaries. FACETS, 2, 301-314. http://doi.org/10.1139/facets-2016-0070
  » http://doi.org/10.1139/facets-2016-0070
• Vethaak, D., & Leslie, H. (2016). Plastic debris is a human health issue. Environmental Science & Technology, 50(13), 6825-6826. http://doi.org/10.1021/acs.est.6b02569
  » http://doi.org/10.1021/acs.est.6b02569
• Wang, J., Jinping, P., Tan, Z., Gao, Y., Zhan, Z., Chen, Q., & Cai, L. (2017). Microplastics in the surface sediments from the Beijiang River littoral zone: Composition, abundance, surface textures and interaction with heavy metals. Chemosphere, 171, 248-258. http://doi.org/10.1016/j.chemosphere.2016.12.074
  » http://doi.org/10.1016/j.chemosphere.2016.12.074
• Wang, Z., Su, B., Xu, X., Di, D., Huang, H., Mei, K., Dahlgren, R., Zhang, M., & Shang, X. (2018). Preferential accumulation of small (<300 μm) microplastics in the sediments of a coastal plain river network in eastern China. Water Research, 144, 393-401. http://doi.org/10.1016/j.watres.2018.07.050
  » http://doi.org/10.1016/j.watres.2018.07.050
• Welden, N., & Lusher, A. (2020). Microplastics: from origin to impacts. In T. M. Letcher (Ed.), Plastic waste and recycling (pp. 223-249). Cambridge: Academic Press. http://doi.org/10.1016/B978-0-12-817880-5.00009-8
  » http://doi.org/10.1016/B978-0-12-817880-5.00009-8
• Wijnen, J., Ragas, A., & Kroeze, C. (2019). Modelling global river export of microplastics to the marine environment: sources and future trends. The Science of the Total Environment, 673, 392-401. http://doi.org/10.1016/j.scitotenv.2019.04.078
  » http://doi.org/10.1016/j.scitotenv.2019.04.078
• World Economic Forum. Ellen MacArthur Foundation &d McKinsey & Company. (2016). The New Plastics Economy — Rethinking the future of plastics Retrieved in 2024, March 2, from http://www.ellenmacarthurfoundation.org/publications
  » http://www.ellenmacarthurfoundation.org/publications
• Wright, S., Thompson, R., & Galloway, T. (2013). The physical impacts of microplastics on marine organisms: a review. Environmental Pollution, 178, 483-492. http://doi.org/10.1016/j.envpol.2013.02.031
  » http://doi.org/10.1016/j.envpol.2013.02.031
• Xiong, X., Zhang, K., Chen, X., Shi, H., Luo, Z., & Wu, C. (2018). Sources and distribution of microplastics in China’s largest inland lake e Qinghai Lake. Environmental Pollution, 235, 899-906. http://doi.org/10.1016/j.envpol.2017.12.081
  » http://doi.org/10.1016/j.envpol.2017.12.081
• Xu, Q., Xing, R., Sun, M., Gao, Y., & An, L. (2020). Microplastics in sediments from an interconnected river-estuary region. The Science of the Total Environment, 729, 139025. http://doi.org/10.1016/j.scitotenv.2020.139025
  » http://doi.org/10.1016/j.scitotenv.2020.139025
• Yang, L., Zhang, Y., Kang, S., Wang, Z., & Wu, C. (2021). Microplastics in freshwater sediment: A review on methods, occurrence, and sources. The Science of the Total Environment, 754, 141948. http://doi.org/10.1016/j.scitotenv.2020.141948
  » http://doi.org/10.1016/j.scitotenv.2020.141948
• Zhang, K., Gong, W., Lv, J., Xiong, X., & Wu, C. (2015). Accumulation of floating microplastics behind the Three Gorges Dam. Environmental Pollution, 204, 117-123. http://doi.org/10.1016/j.envpol.2015.04.023
  » http://doi.org/10.1016/j.envpol.2015.04.023
• Zhang, L., Liu, J., Xie, Y., Zhong, S., Yang, B., Lu, D., & Zhong, Q. (2019). Distribution of microplastics in surface water and sediments of Qin river in Beibu Gulf, China. The Science of the Total Environment, http://doi.org/10.1016/j.scitotenv.2019.135176
  » http://doi.org/10.1016/j.scitotenv.2019.135176
• Zhang, Y., Kang, S., Allen, S., Allen, D., Gao, T., & Sillanpää, M. (2020). Atmospheric microplastics: A review on current status and perspectives. Earth-Science Reviews, 203, 103118. http://doi.org/10.1016/j.earscirev.2020.103118
  » http://doi.org/10.1016/j.earscirev.2020.103118
• Zimmermann, L., Göttlich, S., Oehlmann, J., Wagner, M., & Völker, C. (2020). What are the drivers of microplastic toxicity? Comparing the toxicity of plastic chemicals and particles to Daphnia magna. Environmental Pollution, 267, 115392. http://doi.org/10.1016/j.envpol.2020.115392
  » http://doi.org/10.1016/j.envpol.2020.115392

Edited by

Editor in-Chief:

Adilson Pinheiro

Associated Editor:

Ibraim Fantin da Cruz

Publication Dates

• Publication in this collection
  18 Oct 2024
• Date of issue
  2024

History

• Received
  02 Mar 2024
• Reviewed
  28 June 2024
• Accepted
  05 Aug 2024