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Christian Scherer

Bio: Christian Scherer is an academic researcher from Goethe University Frankfurt. The author has contributed to research in topics: Microplastics & Chironomus riparius. The author has an hindex of 10, co-authored 12 publications receiving 1238 citations.

Papers
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Journal ArticleDOI
TL;DR: To assess the environmental risk associated with microplastics, comprehensive data on their abundance, fate, sources, and biological effects in freshwater ecosystems are needed.
Abstract: While the use of plastic materials has generated huge societal benefits, the ‘plastic age’ comes with downsides: One issue of emerging concern is the accumulation of plastics in the aquatic environment. Here, so-called microplastics (MP), fragments smaller than 5 mm, are of special concern because they can be ingested throughout the food web more readily than larger particles. Focusing on freshwater MP, we briefly review the state of the science to identify gaps of knowledge and deduce research needs. Environmental scientists started investigating marine (micro)plastics in the early 2000s. Today, a wealth of studies demonstrates that MP have ubiquitously permeated the marine ecosystem, including the polar regions and the deep sea. MP ingestion has been documented for an increasing number of marine species. However, to date, only few studies investigate their biological effects. The majority of marine plastics are considered to originate from land-based sources, including surface waters. Although they may be important transport pathways of MP, data from freshwater ecosystems is scarce. So far, only few studies provide evidence for the presence of MP in rivers and lakes. Data on MP uptake by freshwater invertebrates and fish is very limited. While the research on marine MP is more advanced, there are immense gaps of knowledge regarding freshwater MP. Data on their abundance is fragmentary for large and absent for small surface waters. Likewise, relevant sources and the environmental fate remain to be investigated. Data on the biological effects of MP in freshwater species is completely lacking. The accumulation of other freshwater contaminants on MP is of special interest because ingestion might increase the chemical exposure. Again, data is unavailable on this important issue. MP represent freshwater contaminants of emerging concern. However, to assess the environmental risk associated with MP, comprehensive data on their abundance, fate, sources, and biological effects in freshwater ecosystems are needed. Establishing such data critically depends on a collaborative effort by environmental scientists from diverse disciplines (chemistry, hydrology, ecotoxicology, etc.) and, unsurprisingly, on the allocation of sufficient public funding.

933 citations

Journal ArticleDOI
TL;DR: It is demonstrated that freshwater invertebrates have the capacity to ingest microplastic items, however, the quantity of uptake depends on their feeding type and morphology as well as on the availability of microplastics.
Abstract: Microscopic plastic items (microplastics) are ubiquitously present in aquatic ecosystems. With decreasing size their availability and potential to accumulate throughout food webs increase. However, little is known on the uptake of microplastics by freshwater invertebrates. To address this, we exposed species with different feeding strategies to 1, 10 and 90 µm fluorescent polystyrene spheres (3–3 000 particles mL−1). Additionally, we investigated how developmental stages and a co-exposure to natural particles (e.g., food) modulate microplastic ingestion. All species ingested microplastics in a concentration-dependent manner with Daphnia magna consuming up to 6 180 particles h−1, followed by Chironomus riparius (226 particles h−1), Physella acuta (118 particles h−1), Gammarus pulex (10 particles h−1) and Lumbriculus variegatus (8 particles h−1). D. magna did not ingest 90 µm microplastics whereas the other species preferred larger microplastics over 1 µm in size. In C. riparius and D. magna, size preference depended on the life stage with larger specimens ingesting more and larger microplastics. The presence of natural particles generally reduced the microplastics uptake. Our results demonstrate that freshwater invertebrates have the capacity to ingest microplastics. However, the quantity of uptake depends on their feeding type and morphology as well as on the availability of microplastics.

259 citations

Journal ArticleDOI
TL;DR: There is a need for a structured approach to the testing of different properties to identify which are the most relevant drivers of microplastic toxicity, including particle size, particle shape, crystallinity, surface chemistry, and polymer and additive composition.
Abstract: "Microplastic" is an umbrella term that covers many particle shapes, sizes, and polymer types, and as such the physical and chemical properties of environmental microplastics will differ from the primary microbeads commonly used for ecotoxicity testing. In the present article, we discuss the physical and chemical properties of microplastics that are potentially relevant to their ecotoxicity, including particle size, particle shape, crystallinity, surface chemistry, and polymer and additive composition. Overall, there is a need for a structured approach to the testing of different properties to identify which are the most relevant drivers of microplastic toxicity. In addition, the properties discussed will be influenced by and change depending on environmental conditions and degradation pathways. Future challenges include new technologies that will enter the plastic production cycle and the impact of these changes on the composition of environmental microplastics. Integr Environ Assess Manag 2017;13:470-475. © 2017 SETAC.

183 citations

Journal ArticleDOI
TL;DR: In a global context, MP levels in the Elbe relate to the lower to middle section of the global range of MP concentrations determined for rivers worldwide, highlighting that elevated MP levels are not only found in single countries or continents, but that MP pollution is an issue of global concern.

172 citations

Journal ArticleDOI
TL;DR: It is argued that the autecology needs to be taken into account and that research should focus on identifying traits that render species susceptible to microplastic exposure, as well as the species-specific morphological, physiological and behavioral traits.

165 citations


Cited by
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Journal ArticleDOI
TL;DR: By identifying and synthesizing dispersed data on production, use, and end-of-life management of polymer resins, synthetic fibers, and additives, this work presents the first global analysis of all mass-produced plastics ever manufactured.
Abstract: Plastics have outgrown most man-made materials and have long been under environmental scrutiny. However, robust global information, particularly about their end-of-life fate, is lacking. By identifying and synthesizing dispersed data on production, use, and end-of-life management of polymer resins, synthetic fibers, and additives, we present the first global analysis of all mass-produced plastics ever manufactured. We estimate that 8300 million metric tons (Mt) as of virgin plastics have been produced to date. As of 2015, approximately 6300 Mt of plastic waste had been generated, around 9% of which had been recycled, 12% was incinerated, and 79% was accumulated in landfills or the natural environment. If current production and waste management trends continue, roughly 12,000 Mt of plastic waste will be in landfills or in the natural environment by 2050.

7,707 citations

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TL;DR: A global model of plastic inputs from rivers into oceans based on waste management, population density and hydrological information is presented to provide baseline data for ocean plastic mass balance exercises, and assist in prioritizing future plastic debris monitoring and mitigation strategies.
Abstract: Plastics in the marine environment have become a major concern because of their persistence at sea, and adverse consequences to marine life and potentially human health. Implementing mitigation strategies requires an understanding and quantification of marine plastic sources, taking spatial and temporal variability into account. Here we present a global model of plastic inputs from rivers into oceans based on waste management, population density and hydrological information. Our model is calibrated against measurements available in the literature. We estimate that between 1.15 and 2.41 million tonnes of plastic waste currently enters the ocean every year from rivers, with over 74% of emissions occurring between May and October. The top 20 polluting rivers, mostly located in Asia, account for 67% of the global total. The findings of this study provide baseline data for ocean plastic mass balance exercises, and assist in prioritizing future plastic debris monitoring and mitigation strategies. Rivers provide a major pathway for ocean plastic waste, but effective mitigation is dependent on a quantification of active sources. Here, the authors present a global model of riverine plastic inputs, and estimate annual plastic waste of almost 2.5 million tonnes, with 86% sourced from Asia.

2,083 citations

Journal ArticleDOI
TL;DR: This review critically evaluates the current literature on the presence, behaviour and fate of microplastics in freshwater and terrestrial environments and, where appropriate, draws on relevant studies from other fields including nanotechnology, agriculture and waste management.

1,864 citations

Journal ArticleDOI
TL;DR: The issue of microplastics in freshwater systems is reviewed to summarise current understanding, identify knowledge gaps and suggest future research priorities.

1,688 citations

Journal ArticleDOI
TL;DR: The sources and global distribution of microplastics in the environment, the fate and impact on marine biota, especially the food chain are described and the control measures discussed are those mapped out by both national and international environmental organizations for combating the impact from microplastic pollution.

1,487 citations