Freshwater Microplastics

For all customers who have a standing order for the print version of The Handbook of Environmental Chemistry, we offer free access to the electronic volumes of the Series published in the current year via SpringerLink. The last part of the book is devoted to the question of how society and microplastics interact.

A Brief Overview of Plastic Development

Describing Plastic Materials

Microplastics as Contaminants of Emerging Concern

Compared to this deliberate use, secondary MPs are formed by the decomposition of larger plastic waste. Once MPs are released or formed in the freshwater environment, they will undergo fate and transport processes.

Environmental Transportation

Environmental Persistence and Degradation

Kinetic fragmentation models have been investigated in the mathematics and physics literature, and polymer degradation kinetics have been extensively investigated in the polymer science literature. Important variables that will affect MP degradation and fragmentation are environmental exposure conditions, polymer properties such as density and crystallinity (Table 3), and the type and amount of chemical additives.

Table 3 Polymer type, density, and crystallinity

Interactions with Other Compounds

The environmental degradation of plastic materials is also discussed further in Klein et al. For example, sorption and diffusion of hydrophobic contaminants is most likely to occur in the amorphous region of a plastic material because the crystalline region consists of more ordered and tightly structured polymer chains.

Uptake and Biological Effects

It is clear, however, that MP will definitely be transferred from the prey to the predator and that - in certain situations - it can remain in the body of the latter for a long time. Bioavailability of MPs and cell penetration of submicron MPs are factors to consider.

Effects of Leaching Chemicals

Overall, an understanding of the relationships between responses at the cellular level and impacts at the population level will be important to determine the broader implications for ecosystem functioning. There are many challenges associated with the characterization of such leachate products due to the potential diversity of physicochemical properties that chemical migrants and degradation products may have.

Biological Effects of Sub-micrometer Plastics

Lambert S, Sinclair CJ, Boxall ABA (2014) Occurrence, degradation and effects of polymer-based materials in the environment. Nano- and microplastics and engineered nanomaterials have the potential to act as vectors for co-pollutants in the environment.

Table 4 A hypothetical chemical mixture risk assessment based on the chemical components of PUR flexible foam with TBBPA as a flame retardant (units are mg/L)

Nano- and Microplastics in Standard Ecotoxicity Tests

While aging is potentially important for nanomaterials, and for nano- and microplastics, in the environment, the relevant aging processes and kinetics may differ. Based on current knowledge, nano- and microplastics may have higher nucleation stability and lower release of soluble compounds than certain engineered nanomaterials (especially metal and metal oxide nanomaterials such as ZnO and Ag).

Detecting and Quantifying Particle Uptake

The abundance of microplastics reported in the studies varied by more than three orders of magnitude. Environmental degradation of plastics is an important factor in the formation, distribution and accumulation of microplastics in the aquatic system.

Sampling of Microplastics

1 Possible strategies described in the literature for the analysis of microplastics in sediment and water samples from sampling to reporting of results. Other studies report sampling in relation to the lowest wreck line of the water body [9,10].

Sample Preparation

Differences between microplastics studies for coastal sediment sampling begin with the selection of the sampled area. If plastic containers are included for transport, blanks should also be analyzed to quantify their contribution to the microplastic load of the sample [8, 10].

Identification of Microplastics

Between 11,000 and 220,000 microplastic particles per km2 were detected in the surface waters of the six lakes mentioned. Rocha-Santos T, Duarte AC (2015) A critical review of analytical approaches to the occurrence, fate and behavior of microplastics in the environment.

Fig. 2 Degradation pathways of synthetic polymers in the aquatic environment with degradation processes involved and intermediate steps until complete mineralization

Microplastics Encountered in the Different Compartments

A map of Paris Megacity is presented as well as the location of the different sampling sites (Fig.1). Fragments were detected at the outlet of the Seine Aval WWTP because larger volumes were integrated.

Table 1 Used methods and sampled volumes for the various compartments

Fiber Fluxes in Different Compartments

Therefore, based on both scenarios (5 and 60% synthetic fibers), on the scale of the Paris agglomeration, between 21013 and 11015 MP fibers are released into the wastewater annually. CSO discharges from the Paris combined sewer system are approximately 21 million m3 per year1, which corresponds to a potential input to freshwater of between 4 and 5 1012 fibers per year.

Comparison of Microplastic Sources in Freshwater

On the other hand, a sedimentation process in the sewage network is possible during dry weather periods. For the fragments, only five different campaigns were carried out at the different sites (Fig. 1).

Fibers in the Seine and Marne Rivers

Fragments on the other hand are less abundant, and sampling of higher volumes is mandatory, requiring large mesh size (330μm). In addition, because fibers seem to characterize the case study area and are less investigated than previously published freshwater investigations, a long-term monitoring from April 2014 to December 2015 was carried out at four stations (P2 -P5) on the Seine. River from upstream to downstream of Paris plus a station on the River Marne (P1).

Comparison with the Fragments

Murphy F, Ewins C, Carbonnier F, Quinn B (2016) Wastewater treatment works (WwTW) as a source of microplastics in the aquatic environment. These studies suggest that inland waters are facing similar problems of microplastic accumulation as found in the oceans [22,23].

Characteristics of the Microplastics

While sampling microplastics from lakeshore sediment in the Siling Co Basin, different size distribution patterns were observed from different sampling sites [23]. 23] investigated the surface textures of microplastics from lakeshore sediments in the Siling Co Basin, and mechanical weathering was more frequently observed, which was attributed to the windy weather condition in the study area.

Polymer Types Found

The abundance of microplastics in the Three Gorges Reservoir and Taihu Lake in China are among the highest reported in inland waters worldwide. Ivar do Sul JA, Costa MF (2014) The present and future of microplastic pollution in the marine environment.

Africa, the Anthropocene, and Plastic Pollution

Finally, we discuss the current challenges and future needs of MP research in African freshwaters. Finally, we discuss the current challenges and knowledge gaps and future research needs that require attention to gain a better understanding of the presence, sources and fate of MPs in inland African waters.

African Freshwaters and the Potential for MP Pollution

Despite the lack of scientific confirmation of MPs in Africa's freshwater, it would be unfair to say that there is a lack of recognition of the plastic issue. Analysis of the distribution of MPs showed that coastal currents rather than local sources were responsible for the variation in abundance between beaches.

Fig. 1 Map of the African continent showing major freshwater bodies (rivers numbered 1–6 and lakes lettered A–F)

Presence of MPs in Freshwaters

Plastics in the Tanzanian Waters of Lake Victoria

Importantly, NaOH digestion has minimal impact on the chemical and physical state of plastics, especially compared to strong acid digestion, while also showing the Mwanza region. a) Nile Perch and Nile Tilapia were purchased from the port market of Mwanza (regional capital). In addition to confirming the uptake of MPs by freshwater fish species [48], the chemical composition of the MPs was also determined.

Plastics and MPs in Lake Victoria

Future studies could also consider the trophic transfer of MPs through the freshwater food chain, particularly in the case of Nile perch, which are known to feed on smaller fish (haplochromine cichlids) and gastropods, as well as any potential. In the following section, we consider the current challenges for MP research and mitigation in Africa and discuss future research needs.

Current Challenges

In most African countries, LP pollution is not recognized as an emerging issue of concern, despite efforts to charge, reduce and ban the use of plastic bags [26,27]. A number of countries receive financial aid, and under these circumstances, and understandably, the study of LP pollution is not of the highest priority.

Future Research Needs

Ryan PG, Moore CJ, van Franeker JA, Moloney CL (2009) Monitoring the abundance of plastic debris in the marine environment. The occurrence and distribution of plastic debris in the marine environment has been studied even in the most remote areas, such as the Arctic [11] and the ocean floor [12].

Fig. 1 Schematic representation of the different processes playing a role in the transport of macroplastic in a river and lake

Emission-Based Mass Flow Modeling

Current knowledge on the use of nano- and microplastics in consumer products is limited, so this mass flow modeling study used a generic approach with many assumptions, which contrasts with the approaches used in more advanced multimedia mass balance models, life cycle perspective models or probabilistic material flow models.

Global River Models

Multimedia Modeling

We provide a first implementation for plastic in SB4N in this review (Fig.3), which has not been previously published. SB4N is parameterized for the Rhine catchment area, assuming an initial emission to the soil and surface water compartments of 50% each of the total emission.

Spatiotemporally Explicit Models

Modeling the transport of microplastic waste in the Thames River Basin (UK) Nizzetto et al. These processes affect the hydrodynamic behavior and particle size distribution but, according to the authors, need to be better understood before they can be incorporated into the model.

Data and Knowledge Gaps with Respect to Further Model Development

5 Recommendations and guidelines for the development of plastic waste fate models from a risk assessment perspective. Development of freshwater fate models could also benefit from experimental and model studies of marine plastic aggregation, fragmentation and biofouling.

Comparing the Models: What Model for Which Question?

For more accurate local estimates of plastic waste concentrations, system-specific zero-D mass balance approaches can be used for smaller systems, such as lakes [63]. However, to better account for variability, spatiotemporally explicit models in 1, 2 or 3 dimensions can be used.

Fate and Exposure Models in the Context of ERA for Plastic in Freshwater Systems

Huerta Lwanga E, Gertsen H, Gooren H et al (2016) Microplastics in the terrestrial ecosystem: implications for Lumbricus terrestris (Oligochaeta, Lumbricidae). Eriksen M, Mason S, Wilson S et al (2013) Microplastic pollution in the surface waters of the Laurentian Great Lakes.

The Role of Feeding Types

These groupings imply clear boundaries, although some species feed on multiple food sources (eg generalists, omnivores) or have the ability to switch between food sources (opportunistic foragers). To understand the capacity of different species to feed on specific size classes, limnologists have often used polymer beads as tracers [8–10].

Table 1 Summary of the results of uptake studies with microplastic particles and freshwater species

The Role of Particle Size, Shape, and Taste

Currently, the majority of the available literature focuses on MP beads, and it remains unclear whether the studied species have similar feeding rates on non-spherical MPs (e.g. fibers, fragments). The essential role of "taste" in zooplankton feeding was recognized when discussing the comparability of feeding studies with synthetic microspheres and labeled bacteria or algae [9,10,15].

Fig. 1 Estimated feeding size ranges on microplastic particles (a). Dotted lines and question marks indicate the lack of min to max limits based on ingested size classes

Conclusion

Therefore, we hypothesize a similar pattern regarding species-specific size and taste discrimination: Some species will feed directly on MPs available in their food size range, while more selective feeders will avoid ingesting MPs. Generalist filter feeders will actively and directly ingest MPs from the water column or sediments in the size range of their typical diet, whereas more specialized feeders (eg, fluid feeders, predatory carnivorous feeders) will indirectly ingest MPs attached to their prey.

Physical Impacts

The transfer of MPs to tissues induces cellular damage as well as inflammatory responses in the marine filter-feeding mussel M. Indeed, histopathological analysis revealed an inflammatory response and accumulation of lipids in the liver as well as oxidative stress.

Chemical Impacts

Several laboratory studies illustrate the ability of MP to modify the adverse effects of chemicals by affecting bioavailability or acting as an additional stressor. In addition to the capacity of MP to influence the bioavailability of toxic compounds, Besseling et al.

Biofilm-Related Impacts

Jeong C-B, Won E-J, Kang H-M et al (2016) Size-dependent toxicity of microplastics, induction of oxidative stress and activation of p-JNK and p-P38 in monogonont ringworm (Brachionus koreanus). Watts AJR, Urbina MA, Goodhead RM et al (2016) Impact of microplastics on gills.

Fig. 2 Schematic overview of interactions between microplastics, biota, and ecosystems

Factors Contributing to Biofilm Formation and Composition

Many factors driving the development of plastisphere communities are likely similar between freshwater and marine habitats. Environmental conditions such as temperature, salinity, pressure and the availability of light and oxygen are likely to influence the development of plastic-associated biofilms (Fig. 1) [29,31].

Examples of Microbial-Microplastic Interactions in Freshwater Habitats

46] was to investigate the growth of a microalga (Chlamydomonas reinhardtii) on plastic particles over time, determine the effect of plastic type on algae growth, and measure particle aggregation. The authors found little effect of plastic (high-density polyethylene [HDPE] or polypropylene [PP]) on algae growth, but contact with polymer particles altered the expression of genes for some sugars used in extracellular polysaccharides.

Fig. 2 Scanning electron micrograph showing a biofilm attached to a HDPE fragment incubated in aerobic wastewater for 6 months

Potential for Pathogenesis, Toxicant Transfer, and Biodegradation

However, due to a lack of research on plasticizer physiology, the long residence times of plastic waste, and the ability of polymers to adsorb polyaromatic hydrocarbons [11,12], the mechanisms underlying the recruitment of hydrocarbon degraders onto microplastics are unknown. Research into plastic-related biofilms has focused on surface waters (despite the long-term accumulation of microplastics in sediments and investigations of benthic plasticosphere compositions have been limited to marine habitats [21,47].

Interactions with Higher Organisms and the Wider Environment