Microplastic pollution in small rivers along rural-urban gradients: Variations across catchments and between water column and sediments

Factors influencing the vertical distribution and transport of plastics in riverine environments: Theoretical background and implications for improved field study design

Rivers have been widely recognized as important conduits and accumulation sites for plastics. Accurately describing plastic fate and transport in these systems is essential for the development of numerical models, estimating loads to oceans, and implementing effective management strategies. However, plastic transport mechanisms within fluvial environments are not well understood, and field studies often do not provide sufficient information to test analytical models of transport. Sediment transport has dynamical similarities to plastics transport in water bodies, enough to warrant further investigation into how principles from sediment transport can be used to guide the study of plastics. In this review, we summarize fundamentals from sediment transport research and their application to plastics, then use these to make suggestions of clarifying research questions and riverine field study design with the goal of generating more insightful data that can be used to understand and predict plastic fate and transport. We focus specifically on factors influencing plastic vertical distribution and movement in the water column, as variations in this direction have historically been overlooked or oversimplified in rivers.

Microplastic contamination in green mussels (Perna viridis Linnaeus, 1858) from traditional seafood markets in Jakarta, Indonesia, and an evaluation of potential hazards

Marine organisms, especially mussels, can efficiently take up microplastics (MPs) through their filtration processes. This study evaluated the characteristics of MPs in green mussels (Perna viridis) sold at traditional seafood markets in Jakarta, Indonesia. The polymers of MPs were examined using Fourier Transform Infrared spectroscopy, while the chemical components of MPs in green mussels were analyzed using Gas Chromatography-Mass Spectrometry. The MPs identified in green mussels sold at traditional seafood markets in Jakarta are predominantly of fiber type, display a black coloration, and measure <100 μm in size. The density of these microplastics in green mussels is uniform across all traditional markets. The concentration of microplastics in green mussels correlates positively with the length of the green mussel shell. The average annual consumption of mussel products by people in Jakarta was 11,170 items/year/person. Green mussels from Jakarta exhibited a significantly elevated polymer hazard index (III), indicating the presence of polymers categorized as high risk. Certain plasticizers (phthalates) and specific additive chemicals (phenol, butylated hydroxytoluene, and hexadecanamide) were also present in green mussels sourced from traditional markets in Jakarta. These substances are toxic and have a negative impact on both aquatic life and humans.

Microplastic pollution in surface waters of urban canals in a highly urbanized city (Dunkirk, Northern France): influence of dry and wet periods on discharge to the sea

Microplastic (MP) pollution is a growing environmental concern, with urban waterways constituting critical pathways for transporting MPs into marine ecosystems. This study investigated the distribution, abundance, diversity, and flux of MPs in six urban canals influenced by urban and industrial activities in the city of Dunkirk, during dry and wet (rainy) periods. Plastic abundance was higher during the wet period (18.25 ± 22.16 particles/m3) compared to the dry period (8.14 ± 7.76 particles/m3), reflecting increased inputs from surface runoff and stormwater discharge. Spatial trends revealed distinct site-specific patterns, with the most urbanized sites (S1 and S6) exhibiting the highest abundances. Fibers were the dominant type accounting for over 75% of particles at all sites. PET was the main polymer in urban sites, while PE and PP were more prevalent in industrial zones. The estimated annual flux of MP at the outlet ranged from 19.21 × 106 ± 26.12 × 105 particles/year/m3 (dry period) to 23.97 × 107 ± 19.41 × 106 particles/year/m3 (wet period), revealing the significant contributions of urban canals to coastal pollution. These results highlight the need for improved source control and stormwater management to better assess and mitigate MP pollution in urban aquatic systems.

Spatial and temporal variations of microplastics in the lower Chao Phraya River, Thailand: an investigation during the COVID-19 pandemic period

This study systematically investigated the abundance, characteristics, and spatial and temporal variations of microplastics (MPs) in the lower Chao Phraya River, Thailand, during the COVID-19 pandemic. The study revealed an average MP abundance of 8.3 ± 5.8 particles/m3, mainly composed of polyethylene (PE) and polypropylene (PP) with fibers and fragments being the predominant shapes. Spatially, MP concentrations exhibited a notable increase downstream, particularly in highly urbanized areas. Temporally, MP concentrations showed slight elevation during the wet season, with clear seasonal variations in MP size and shape distributions attributed to the influence of urban storm runoff. Despite expectations of heightened MP pollution due to the COVID-19 pandemic, the study suggests a potential reduction in MP abundance, likely attributed to decreased socio-economic activities. Nonetheless, the long-term effects remain uncertain, underscoring the imperative for continuous monitoring and effective environmental management strategies.

Decadal changes in microplastic accumulation in freshwater sediments: Evaluating influencing factors

Microplastics are small plastic particles with sizes ranging between 1 μm and 5 mm. Microplastics can originate from macro plastics and degrade to a smaller size or be produced directly by manufacturers. Few studies have examined microplastic contamination in freshwater sediment cores to estimate changes in microplastic contamination over time. We present the results of a study that examined sediment cores from four watersheds, Kiskiminetas River, Blacklick Creek, Raystown Lake, and Darby Creek, in Pennsylvania, USA to reveal the history of microplastic accumulation and factors that contribute to microplastic distribution. The abundance and morphology of microplastics varied over time and between these four locations. The highest microplastic abundance was found in Raystown Lake, ranging from 704 to 5397 particles kg-1 with fiber as the dominant microplastic type, while Darby Creek (0-3000 particles kg-1), Kiskiminetas River (0-448 particles kg-1), and Blacklick Creek (0-156 particles kg-1) had lower microplastic concentration. Moreover, Darby Creek had the most diverse microplastic morphology and a trend of decreasing concentration with depth. Although the Darby Creek watershed has the most developed area and highest population density, it did not have the highest microplastic concentration. Averaged over the four cores, microplastic abundance increased as global plastics production increased from the 1950s-2010s. Our findings provide insights into the fate and transport of microplastic contamination in freshwater environments, which is vital to establishing sustainable mitigation strategies.

Microbial communities on microplastics from seawater and mussels: Insights from the northern Adriatic Sea

Microplastics, synthetic solid particles of different sizes (< 5 mm), pose a major challenge to marine ecosystems. Introducing microplastics into the marine environment leads to the formation of complex microbial communities, a topic of growing interest in environmental research. For this study, we selected an area in the northern Adriatic Sea, less affected by human activities, to understand how pristine environmental conditions influence microbial colonization of microplastics. Samples of coastal seawater and Mediterranean mussels (Mytilus galloprovincialis) were collected in a mussel farm near Debeli rtič of the Slovenian coast. Microplastics were isolated, visually and chemically analyzed and DNA was extracted for metagenomics. In the marine water column, 12.7 microplastics per m3 water column and 0.58 microplastics per individual mussel were found. Sufficient DNA was available to analyze six particles, five originating from seawater, and one from a mussel. This was the first-ever sequenced microplastic particle from a mussel. Genera of Pseudomonas and Serratia were identified in all samples. In one of the samples, the most abundant was a marine genus Pseudoalteromonas, while in another sample Campylobacter was present with >30 % abundance. The microbiomes of the mussel- and seawater-isolated particles were similar, suggesting a common microbial colonization pattern, which may have implications for the transfer of microplastic-associated microbes, including potential pathogens, through the food web to the consumers. Microplastic pollution is a complex issue requiring further research, especially regarding microbial biofilms, pathogen colonization and the potential of pathogen transmission via microplastic particles. Our findings enhance the understanding of microplastic pollution in the Adriatic Sea and stress the necessity for comprehensive strategies to mitigate the impact on marine ecosystems.

Evaluating the sources of microplastic contamination and quantifying its abundance in the Balu River, Dhaka, Bangladesh

Microplastics (MPs) are prevalent environmental pollutants due to their durable composition, extensive use, and improper disposal. Despite their widespread presence, rivers have received less attention in microplastic research than other water bodies. This study focused on investigating the origins, prevalence, spatial distribution, and physicochemical characteristics of microplastics in the surface waters of the Balu River, located in Dhaka, Bangladesh. Surface water samples were collected at six sampling sites of Balu River (each about 1-5 km apart) adjacent to the footwear industry, jute factory, textile mill, paper mill, agro and beverage factory, and cement plant. The study found that the average concentration of microplastics in the sampled water bodies was 102.5 ± 12.83 (items/l). Samples near the textile mill had the highest microplastic abundance (122 ± 18 items/l), while the cement plant had the lowest (58.5 ± 8 items/l). Analysis using a stereomicroscope revealed that fibers (29%), microplastics smaller than 100 µm (45%), and transparent microplastics (19%) were the most prevalent types observed in terms of shape, size, and color, respectively. Furthermore, scanning electron microscopy (SEM) observation suggested the potential for additional degradation of these microplastics into smaller particles, potentially reaching the nanoplastic scale. Additionally, Fourier transform infrared (FTIR) analysis identified 07 distinct polymer types among the microplastics: nylon (24%), polyvinyl chloride (19%), high-density polyethylene (17%), low-density polyethylene (14%), polystyrene (12%), polypropylene (7%), and nitrile (7%). The findings of this study serve as a crucial indicator of microplastic contamination, providing valuable insights into the sources and magnitude of microplastic pollution within the significant freshwater ecosystem of Balu River, Bangladesh, particularly focusing on its river systems.

Microplastics in a small river: Occurrence and influencing factors along the river Oker, Northern Germany

Much attention regarding the environmental pollution by plastics had focused on the Oceans. More recently, contamination of freshwater ecosystems has been addressed but information from smaller rivers in moderately populated catchments is still comparatively scarce. This study explored the microplastic (MP) occurrence in the small regional river Oker, Northern Germany (catchment area 1822 km2, population of ca. 500,000, discharge approx. 12 m3 s-1). MPs (fibers and fragments in the size range 0.3-5 mm, identification by microscopy) were found in all 10 in-stream samples collected along the course of the river, ranging between 28 and 134 particles m-3 with an overall average of 63 particles m-3. This MP concentration found in the small river Oker is similar to, or higher than, that reported for larger rivers in similar environments in Central Europe. On average, higher MP concentration was found at urban (71 particles m-3) compared to rural sampling sites (51 particles m-3). Within the Oker catchment, in-stream MP concentration showed no or low correlation to the catchment-scale factors of catchment size and population. Additional samples taken from three locations directly influenced by discharges of potential MP point sources confirmed wastewater treatment plants of different capacities and an urban rainwater sewer as sources. Our results support findings that MP concentrations in small rivers are crucially influenced by local sources, superimposing linear relationships to factors of catchment size and -population. They show that even small rivers draining moderately populated catchments may exhibit comparatively high concentrations of MPs, and thereby represent underestimated pathways of MP in the environment.

Assessment of Microplastics and Potentially Toxic Elements in Surface Sediments of the River Kelvin, Central Scotland, United Kingdom

Contamination of the environment by microplastics (MPs), polymer particles of <5 mm in diameter, is an emerging concern globally due to their ubiquitous nature, interactions with pollutants, and adverse effects on aquatic organisms. The majority of studies have focused on marine environments, with freshwater systems only recently attracting attention. The current study investigated the presence, abundance, and distribution of MPs and potentially toxic elements (PTEs) in sediments of the River Kelvin, Scotland, UK. Sediment samples were collected from eight sampling points along the river and were extracted by density separation with NaCl solution. Extracted microplastics were characterised for shape and colour, and the polymer types were determined through attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. Pollution status and ecological risks were assessed for both the microplastics and PTEs. Abundance of MPs generally increased from the most upstream location (Queenzieburn, 50.0 ± 17.3 particles/kg) to the most downstream sampling point (Kelvingrove Museum, 244 ± 19.2 particles/kg). Fibres were most abundant at all sampling locations, with red, blue, and black being the predominant colours found. Larger polymer fragments were identified as polypropylene and polyethylene. Concentrations of Cr, Cu, Ni, Pb and Zn exceeded Scottish background soil values at some locations. Principal component and Pearson's correlation analyses suggest that As, Cr, Pb and Zn emanated from the same anthropogenic sources. Potential ecological risk assessment indicates that Cd presents a moderate risk to organisms at one location. This study constitutes the first co-investigation of MPs and PTEs in a river system in Scotland.

Occurrence of organophosphorus flame retardants in Xiangjiang River: Spatiotemporal variations, potential affecting factors, and source apportionment

The environmental occurrence of organophosphorus flame retardants (OPFRs) is receiving increasing attention. However, their distribution in the Xiangjiang River, an important tributary in the middle reaches of the Yangtze River, is still uncharacterized, and the potential factors influencing their distribution have not been adequately surveyed. In this study, the occurrence of OPFRs in the Xiangjiang River was comprehensively investigated from upstream to downstream seasonally. Fourteen OPFRs were detected in the sampling area, with a total concentration (∑OPFRs) ranging from 3.16 to 462 ng/L, among which tris(1-chloro-2-propyl) phosphate was identified as the primary pollutant (ND - 379 ng/L). Specifically, ∑OPFRs were significantly lower in the wet season than in the dry season, which may be due to the dilution effect of river flow and enhanced volatilization caused by higher water temperatures. Additionally, Changsha (during the dry season) and Zhuzhou (during the wet season) exhibited higher pollution levels than other cities. According to the Redundancy analysis, water quality parameters accounted for 35.7% of the variation in the occurrence of OPFRs, in which temperature, ammonia nitrogen content, dissolved oxygen, and chemical oxygen demand were identified as the potential influencing factors, accounting for 28.1%, 27.2%, 24.1%, and 11.5% of the total variation, respectively. The results of the Positive Matrix Factorization analysis revealed that transport and industrial emissions were the major sources of OPFRs in Xiangjiang River. In addition, there were no high-ecological risk cases for any individual OPFRs, although tris(2-ethylhexyl) phosphate and tributoxyethyl phosphate presented a low-to-medium risk level. And the results of mixture risk quotients indicated that medium-risk sites were concentrated in the Chang-Zhu-Tan region. This study enriches the global data of OPFRs pollution and contributes to the scientific management and control of pollution.

Comparison of plastic pollution between waters and sediments in four Po River tributaries (Northern Italy)

The monitoring of plastic contamination in freshwaters is still pioneering in comparison with marine environments, and few studies analyzed the distribution of these pollutants in both aqueous and bottom compartments of continental waters. Therefore, the aim of this study was the comparison of plastic pollution in both waters and sediments of four Po River tributaries (Ticino, Adda, Oglio and Mincio Rivers), which outflow from the main Italian sub-alpine Lakes, in order to establish the strengths and weaknesses of both matrices. The main results pointed out a heterogeneous plastic contamination, with the lowest values in Ticino (0.9 ± 0.5 plastics/m3 in waters and 6.8 ± 4.5 plastics/kg dry weight - d.w. - in sediments) and the highest in Mincio (62.9 ± 53.9 plastics/m3 in waters and 26.5 ± 13.3 plastics/kg d.w in sediments), highlighting a plastic amount in sediments four times higher than waters. Plastic pollution, mainly due to microplastics, was associated principally to a domestic input in both waters and sediments of Ticino and Adda Rivers, as well as in sediments of Oglio, while an industrial pollution was found in waters and sediments of Mincio and Oglio waters. Our data clearly highlighted as the monitoring of both matrices provide complementary information for a holistic risk assessment of these emerging contaminants in freshwaters: the aqueous matrix provides an instantaneous picture of contamination, while sediments the history of pollution.

Modeling the transport of microplastics along river networks

The excessive use of plastics in modern life has led to a significant increase in production and a corresponding rise in plastic waste generation. The slow degradation of plastics results in the introduction and accumulation of microplastics (MP) in the environment, posing environmental and health risks. River networks, acting as conduits between terrestrial and marine environments, play a crucial role in controlling the transport of MP. Predicting the complex processes of MP pathways in these environments is an ongoing challenge. To address this issue, we propose a model that integrates the advection-dispersion equation with anthropogenic MP loads and hydraulic river network characteristics. The validity of the model was assessed using literature data from three river networks worldwide. Model results show a good agreement between predictions and field observations (R2=0.72). Consequently, predicted MP data was used to perform a potential pollution assessment through the pollution load index, revealing in most cases higher MP contamination in headwaters stream and a dilution effect along the river network. The structure of the proposed model allows its further implementation to account for other transport mechanisms, interactions with other emerging contaminants (i.e., pharmaceuticals), and connections with other riverine environments, making it a valuable tool for understanding and mitigating MP pollution.

Microplastic pollution in rivers of the Adriatic Sea basin in Montenegro: Impact on pollution of the Montenegrin coastline

Concern regarding microplastic (MP) pollution in aquatic ecosystems has increased in recent years with growing awareness of the environmental harm that it causes. While most studies have focused on seas and oceans, knowledge of MP occurrence in freshwater sediments is limited. This study investigated MP concentrations at shore sediments of the Zeta, Morača, and Bojana rivers in Montenegro. The MP concentration in the studied samples varied depending on the river, location, and sampling season. MP abundance in river shore sediments varied between mean values of 145 ± 110 MPs/kg for the Zeta, 169 ± 113 MPs/kg for the Morača, and 180 ± 53.5 MPs/kg dry sediment for the Bojana. In comparison, the mean MP abundance in the three rivers combined was 163.6 ± 96.1 MPs/kg of dry sediment. The identified MPs were mainly fibres and fragments of blue, red and clear color, 0.5-1 mm in size, and mainly composed of polyethylene, polypropylene, polyamide and polyethylene terephthalate. The main contribution of this study is that it provides new insight into MP abundance in freshwater sediments of rivers, where the studied rivers were identified as a potential important sink and source of MP on the Montenegrin coast.

Microplastic contamination in water and sediments of Mahanadi River, India: An assessment of ecological risk along rural-urban area

Worldwide, environmental concerns about MPs pollution have increased. Microplastic contamination that pollutes the ocean is mostly caused by terrestrial transfer from close proximity locations. A study of MPs pollution near coastal locations becomes necessary to address the MPs transit, fate, and mitigation. In the current study MPs pollution in the surface water and sediment of the Mahanadi River estuary was assessed during Pre-MS and MS. The size, shape, and colour of the MPs were determined using a stereomicroscope, and the MPs polymer composition was identified by Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR) spectroscopy. The mean concentration of MPs that were potentially discovered in water was 16.6 ± 5.2 and sediments 197.3 ± 5.4 during Pre-MS. In the MS observed mean abundance of MPs was 15.1 ± 5.4 in water and 164.6 ± 76.9 in sediments. The highest abundant size was smaller than 1 mm; the most prevalent shape were fibers followed by film and fragments; black and white was a prominent colour in water and sediments respectively. Polyesters (PEs), polyethylene (PE), polyvinyl chloride (PVC), polypropylene (PP), polyamide (PA), Polystyrene (PS), and Polycarbonates (PC) were found in the analysis of the chemical composition of MPs in water and sediments samples. The calculated PLI value shows pollution load at category I, with polymer hazard levels at categories III, IV, and V, indicating very high risk. The current research results show that river inflows and fishing-related actions are probably the main causes of MPs pollution.

High spatiotemporal resolution analysis on suspended sediment and microplastic transport of a lowland river

The suspended sediment (SS) and microplastic (MP) transport in rivers is quite a complex process, influenced by several spatially and temporally changing factors (e.g., hydrology, sediment availability, human impact). Researchers usually investigate these factors individually and based on limited repetition in space and time. Therefore, this study aims to compare the driving factors of SS and MP transport by applying dense temporal (72 measurements) and spatial monitoring (at 26 sites). This study was performed on the medium-sized Tisza River, Central Europe. The suspended sediment concentration (SSC) was measured by water sampling and estimated based on Sentinel-2 images, while MP concentration was measured by pumping of water (1 m3). The SSC of the Tisza varied between 12.6 and 322.5 g/m3, whereas the MP concentration ranged 0-129 item/m3. Most of the transported particles were fibers (81-98 %), thus, it was assumed that MPs originated from wastewater. The results reflect that the hydrological conditions basically influence the SS and MP concentrations, as a strong positive correlation was found (ρSSC-MP = 0.6) between them during a year; however, the correlation during floods (minor floods: ρ = 0.63; medium floods: ρ = 0.41) was higher than at low stages (ρ = 0.1). It was assumed that run-off and mobilization of channel materials both contribute to increased SS and MP transport during floods. In contrary, the importance of mobilization of channel materials and wastewater input increase during low stages. The repeated measurements revealed that slope and velocity conditions, proximity of sources, tributaries, and dams influence the longitudinal changes in SS and MP concentrations. However, the effects of tributaries and dams are ambiguous (especially for MP) and require further research. The longitudinal measurements were conducted at low stages; hence, moderate negative correlations (ρ2021 = -0.35; ρ2022 = -0.41) were found between the SS and MP concentrations. Therefore, additional monitoring during (overbank) floods and denser spatial sampling are required to precisely reveal the spatiotemporal changes of SS and MP concentrations in rivers.

Impact of flooding on microplastic abundance and distribution in freshwater environment: a review

Due to smaller particle size (0.1 µm-5 mm), non-biodegradable or slowly degradable nature, and high accumulation capacity in the environment, microplastics are becoming a cause of concern throughout the globe. The abundance and distribution of microplastics in aquatic compartments are strongly influenced by various natural and anthropogenic variables. Hydrodynamic conditions like flood events, caused due to extreme precipitation, accelerate the transport and settlement of microplastics in freshwater bodies. This review highlights the current literature which focuses on the effect of flooding on microplastic abundance, characterization, and distribution in freshwater environments worldwide. However, only limited research papers are identified through focused literature search, as this area of research is relatively new. Most of the studies reported increased and decreased abundance of microplastics in water and sediment samples, respectively, during post-flooding period with the exception of few studies. We also evaluate the post-flooding abundances of different morphological shape and polymer type of microplastics. Fragments, fibers, beads, and film were the most frequently reported microplastic shape and polystyrene, and polyethylene was the dominant polymer type found in freshwater environments. Future research should focus on more advanced techniques to understand microplastic fluxes under flood condition and the dominance of various natural and human-induced factors over one another in determining microplastic abundance. This will further enhance to mitigate microplastic pollution in freshwater environments.

Microplastics distribution in river side bars: The combined effects of water level and wind intensity

Rivers are the main pathway for microplastics (MP) transport toward the ocean. However, the understanding of the processes involved in the deposition and mobilization of MP in rivers, specifically in sediment side bars (SB), remains very limited. The objectives of this study were: (i) to examine the effect of hydrometric fluctuations and wind intensity on the distribution of microplastics (MP < 5 mm) in the SB of large river (the Paraná River), (ii) to determine the characteristics of MP to infer their origin and fate, and (iii) to discuss potential similarities or differences between MP suspended in the water column and MP found in sediment. The SB and water column were sampled during the autumn, winter, and spring of 2018, and the summer of 2019 at different river discharges and wind intensities. >90 % of the MP items found were fiber of polyethylene terephthalate (PET; FT-IR analysis), the most common MP color was blue, and most were in the 0.5-2 mm size range. The concentration/composition of MP varied according to the river discharge and wind intensity. During the falling limb of the hydrograph when discharge is decreasing and sediments are exposed for short periods (13-30 days), MP particles transported by the flow were deposited on temporarily exposed SB, accumulating there in high densities (309-373 items/kg). However, during the drought, when sediments remained exposed for a long time (259 days), MP were mobilized and transported by the wind. During this period (no influence of the flow), MP densities significantly decreased on SB (39-47 items/kg). In conclusion, both hydrological fluctuations and wind intensity played a significant role in MP distribution in SB.

Vertical distribution of microplastics in a river water column using an innovative sampling method

Due to limitations of sampling methods, subsurface water is usually a less well-investigated compartment of the water column when scientists assess microplastic contamination. In this study, microplastic (MP) contamination was assessed in a freshwater river both in surface and subsurface using an innovative sampling method. Microplastic contamination in the lower part of the water column, i.e., near-bottom water and in sediments, was also studied. Three sampling campaigns were carried out during different weather conditions: stormy, rainy, and dry in order to observe their influence on the microplastics vertical distribution. No significant difference was observed between the abundance and types of MPs in surface and subsurface water. The proportion of polymer with theoretical density < 1 (polypropylene d = 0.9, polyethylene d = 0.91-0.95) and polystyrene (d = 0.1-1.06) in the surface and subsurface samples was 73.5%, and this proportion drops to 40.8% for the samples located in the near-bottom water and the sediments. Our results indicate that the MP concentration of the different compartments analyzed can be significantly influenced by rainfall during and prior to the sampling day. This study highlights that in shallow rivers, surface water sampling is representative of the water column MP contamination, but that sampling without taking environmental conditions into account may lead to erroneous estimation of MPs concentration and flux entering the marine environment.

Microplastic patterns in riverine waters and leaf litter: Leaf bag technique to investigate the microplastic accumulation trends in lotic ecosystems

Microplastics (MPs) are one of the major ecological concerns of the last years and despite the increasing interest and the rise of many studies regarding freshwater habitats, many aspects about distribution patterns, transport pathways and impacts of MPs in those systems need to be investigated. The present study characterizes the temporal trends of MP concentrations in waters of a riverine stretch of the northeastern Italy, subject to flow rate variations and investigates the MP accumulations patterns in the leaf litter, simulated in situ via leaf bag technique. MP concentrations in the water were significantly and negatively correlated to the flow rate regimes, with higher concentrations observed during low discharge periods. MPs accumulation in leaf bags agreed with trends observed in the water and the presence of wastewater discharge points positively affects the levels of MP contaminations within the leaf bags. These findings seem to suggest that the maintenance of a hydrological regime at relatively high levels in the investigated system could allow to maintain the self-purifying riverine processes and the disposal of microplastics like any other polluting substance. The use of leaf bag technique for the purpose to investigate MP accumulation trends on field provided useful information, is easy to modulate in terms of time periods and allow to record the evolution of the MP patterns also in relation to high flow rate episodes. Our results suggest that the method can be employed in new a perspective, to improve the knowledge about one of the major threats of the Anthropocene.

Investigation and comparative analysis of ecological risk for heavy metals in sediment and surface water in east coast estuaries of India

The sediments and surface water from 8 stations each from Dhamara and Paradeep estuarine areas were sampled for investigation of heavy metals, Cd, Cu, Pb, Mn, Ni, Zn, Fe, and Cr contamination. The objective of the sediment and surface water characterization is to find the existing spatial and temporal intercorrelation. The sediment accumulation index (I_sed), enrichment index (I_En), ecological risk index (I_EcR) and probability heavy metals (p-HMI) reveal the contamination status with Mn, Ni, Zn, Cr, and Cu showing permissible (0 ≤ I_sed ≤ 1, I_En ˂ 2, I_EcR ≤ 150) to moderate (1 ≤ I_sed ≤ 2, 40 ≤ R_f ≤ 80) contamination. The p-HMI reflects the range from excellent (p-HMI = 14.89-14.54) to fair (p-HMI = 22.31-26.56) in off shore stations of the estuary. The spatial patterns of the heavy metals load index (I_HMc) along the coast lines indicate that the pollution hotspots are progressively divulged to trace metals pollution over time. Heavy metal source analysis coupled with correlation analysis and principal component analysis (PCA) was used as a data reduction technique, which reveals that the heavy metal pollution in marine coastline might originate from redox reactions (FeMn coupling) and anthropogenic sources.

Microplastics Derived from Food Packaging Waste-Their Origin and Health Risks

Plastics are commonly used for packaging in the food industry. The most popular thermoplastic materials that have found such applications are polyethylene (PE), polypropylene (PP), poly(ethylene terephthalate) (PET), and polystyrene (PS). Unfortunately, most plastic packaging is disposable. As a consequence, significant amounts of waste are generated, entering the environment, and undergoing degradation processes. They can occur under the influence of mechanical forces, temperature, light, chemical, and biological factors. These factors can present synergistic or antagonistic effects. As a result of their action, microplastics are formed, which can undergo further fragmentation and decomposition into small-molecule compounds. During the degradation process, various additives used at the plastics' processing stage can also be released. Both microplastics and additives can negatively affect human and animal health. Determination of the negative consequences of microplastics on the environment and health is not possible without knowing the course of degradation processes of packaging waste and their products. In this article, we present the sources of microplastics, the causes and places of their formation, the transport of such particles, the degradation of plastics most often used in the production of packaging for food storage, the factors affecting the said process, and its effects.