100 Plastic Rivers - a global investigation

Rationale: Although local case studies provide evidence of freshwater microplastic (MP) contamination, a local approach limits the potential for generalisation and up-scaling of site-specific research. The absence of systematic freshwater microplastic surveys impedes our understanding of how their concentration, composition and properties vary globally.

Research question: This project aims to understand the distribution of MPs in rivers globally, and in particular how their physical (size, shape, density) and chemical properties (incl. additives such as Bisphenol A (BPA) and Nonylphenol (NP)) differ.  MP characteristic differences are expected in relation to catchment properties, prevalence of primary and secondary MP sources, and hydrodynamic and sediment conditions.

Objective: Develop a simple, robust, low-cost, standardised and well-documented approach for the first coordinated global MP river survey to advance site-specific knowledge towards generic and transferable system level understanding.

Methods: Utilising global partnerships, sediment and water samples are being collected from a range of rivers with a custom-made low-cost yet robust sampling kit. Sediment and water samples collected globally will be returned to the University of Birmingham whereby microplastic contamination will be quantified using various novel techniques such as Nile Red and Thermo-Gravimetric-InfraRed-Gas Chromatography/Mass Spectrometry (TG-IR-GC/MS). The comparison of low-tech (field applicable) and high-tech (laboratory-based) approaches will be utilised to benchmark the utility of the field approaches for routine monitoring. 

All data collected will be GPS tagged and dated, and the results will be compiled into an open-access and FAIR (Finable, Accessible, Interoperable and Re-suable) database hosted by UoB.

Partners involved with Work Package 1: Currently we have partners from French Guiana, Punta Arenas and Argentina – South America.

In Africa we have Nigeria, Sierra Leone, Zambia, Kenya and South Africa. Both Canada and the United States of America are represented, as well as Australia and New Zealand. In Southeast Asia we have partners from Indonesia, Malaysia, Thailand and Cambodia.

We also have 17 partners in the United Kingdom sampling rivers from Scotland, Wales and Great Britain. In Europe partners are located in Spain, Finland, Brussels and Greece.

We are always looking for more partners so if you are currently working on microplastics or already work in a freshwater system and can collect sediment and water samples. The 100 Plastic Rivers team will send you a sample kit and standardised protocol. The samples will then be sent back to UoB for further analyses. 

Rationale: Initial investigations indicate that streambed sediments can be hotspots of microplastic accumulation. However, current technological constraints critically limit the understanding of how microplastic properties affect their transport and accumulation and the release of additives such as BPA and NP from freshwater-sediment interfaces.

Research question: Which processes control the transport and accumulation of microplastics with different shapes, densities, composition and the release of BPA and NP at freshwater-sediment interfaces?

Objective: Analyse microplastic property-dependent transport, accumulation and BPA and NP release under variable hydrodynamic, geomorphological and sediment conditions.

Methods: Details will be added in due course following our analysis of the suitability and robustness of currently available methods.

Rationale: Global assessments of the risks of microplastic accumulation and potential contaminant leaching in freshwater systems require quantitative modelling tools. The current lack of suitable modelling tools for analysing microplastic transport mechanisms, their fate and biogeochemical alteration (e.g. biomolecule adsorption) hampers adequate assessment and management of environmental risks.

Research question: How can transport, accumulation, and BPA and NP release from microplastics be predicted under variable hydrodynamic, biogeochemical and sediment conditions?

Objective: Develop modelling tools for the prediction of microplastic transport and transformation for simulating reactive fluid and microplastic particle flow at freshwater-sediment interfaces including the quantification of BPA and NP release that can be adapted to further contaminants.

Methods: Once the database is available (from WP1 supplemented with data curated from the literature) various modelling approaches will be developed including Bayesian networks and Quantitative Structure Activity Relationships.

Rationale: A profound assessment of microplastic risks to freshwater food webs is currently hampered by the critical knowledge gaps of the drivers for microplastic entry, transfer and biomagnification within the food webs and enhanced toxicity due to Trojan horse effects, when microplastics carry xenobiotics such as BPA and NP directly into the organism.

Research question: What properties of microplastics drive the uptake in the aquatic food webs and does biomagnifying occur under realistic environmental conditions. Do microplastics increase the uptake of BPA and NP via Trojan horse effects and/or biomolecule-enhanced release?

Objective: Identify functional pathways and drivers for microplastic uptake and biomagnification. Quantify ecotoxicological impact through freshwater food webs as well as the potential for enhanced uptake through Trojan horse effects with BPA and NP leaching from ingested microplastics. Biomolecule driven enhanced release from microplastics as a result of attachment to natural organic matter or organism-secreted biomolecules will also be explored.

Methods: Selection of species for individual and food web experiments is currently underway. Lab-scale exposures will be performed with mixtures of microplastics varying in physical and bio-chemical traits to identity potential drivers for uptake and biomagnification. Novel methods for tagging different polymers will be implemented in the mesocosm experiments to aid the identification and propagation of different polymers. Laboratory- based experiments will be carried out to identify concentrations of selected microplastics and their additives, under standardised and realistic exposure conditions over acute and chronic timescales.  Microplastics will be tested virgin and following ageing under realistic exposure conditions, and extensive experience from the field of engineered nanomaterials fate and toxicity (nanotoxicity) will be leveraged. This community has already been working for > 5 years to revise the standard OECD test guidelines, developed initially for dissolved chemicals, to take account of the unique features arising from the large surface of particulate pollutants including microplastics.

 During November 2018 Dr Holly Nel attended both the Pan African Chemistry Network (PACN) congress in Kenya where she was an invited guest and the biannual international microplastic conference (Micro2018) in Lanzarote, Spain. Dr Nel is part of the Global 100 Plastic Rivers team which includes Prof. Stefan Krause, Prof. Iseult Lynch, Prof. Greg Sambrook-Smith and Anna Kukkola. An objective of this Leverhulme Trust funded project is to create a global network and database of freshwater microplastic data. This will provide various stakeholders with comparable microplastic prevalence data from rivers around the world. A key step to developing this network is the formation of global partnerships, which can be greatly assisted by networking at conferences. 

The PACN congress entitled “Managing resources through chemistry: Wealth not Waste” discussed how adding value to waste products can reduce pressure on current landfill space. For example, the use of low-density polyethylene to make bricks was discussed by Alex Kumi-Larbi Jnr from Imperial College London, UK. Dr Nel showcased the 100 Plastic Rivers project on the second day, resulting in the formation of new partnerships with researchers from Kenya, Nigeria, Sierra Leone and Zambia.

Micro2018 entitled “Fate and Impact of Microplastics: Knowledge, Actions and Solutions” was also an excellent opportunity to showcase the 100 Plastic Rivers project and network face to face with potential partners. Researchers from Carleton University, Surfriders-Europe, University of Nottingham and TheOceanCleanUp discussed ways to improve our understanding of river microplastic pollution. Additionally, the conference was attended by biological scientist, chemists, physical geographers, oceanographers, mathematical modellers, social scientists and artists. This meant it was the ideal environment to learn how various researchers are tackling the issue of plastic pollution; as well as to improve our understanding through an interdisciplinary perspective.

As a result of networking and these two conferences the 100 Plastic Rivers project already has 50 partners from 27 countries.  To get involved, email H.A.Nel@bham.ac.uk.

The Association of Commonwealth Universities (ACU) recently held an event at City, University of London. The event was attended by academics and scholars working on one of four thematic topics: gender equality, decolonisation in education, refugee education and sustainability. Dr Holly Nel was invited to attend, along with Refilwe Mofokeng, a 2-month Blue Charter exchange fellow from South Africa, who is currently being supervised by Holly at the University of Birmingham. The event gave participants an opportunity to network and meet the ACU’s new Patron, HRH The Duchess of Sussex. During the course of the day both Holly and Refilwe were able to discuss the issue of microplastics with the Duchess; simultaneously showcasing the current Leverhulme Trust project looking at quantifying microplastic contamination in 100 rivers around the world.

Photo Credit: The Association of Commonwealth Universities (ACU).

Soon we say goodbye to Refilwe Mofokeng, a South African PhD candidate who has been hosted by Prof. Stefan Krause and Dr Holly Nel for the last two months. This was as a result of the Association of Commonwealth Universities (ACU) Blue Charter Fellowship. For more information see link: https://www.acu.ac.uk/scholarships/fellowships/blue-charter-fellowships/. The Blue Charter Fellowship sponsored 35 PhD candidates and earlier career researcher from across the Commonwealth enabling them to conduct research at a host institute. Currently completing her PhD at the University of KwaZulu-Natal, Refilwe investigated the ecotoxicological effects of metals associated with microplastics on estuarine benthos. While at the University of Birmingham her main focus was to study the challenges facing microplastic quantification while ensuring reproducibility. This forms part of the Leverhulme Trust project 100 Plastic Rivers. She was also involved with the investigation of practical and cost-effective tools for microplastic extraction, critically documenting the pros and cons of various techniques for future microplastic monitoring in Africa. Refilwe says her two-month exchange at UoB has given her the chance to interact with scientist from a diverse array of cultures and disciplines either through one on one discussions or through the various workshops she attended.   

Tibbetts, J., Krause, S., Lynch, I., Sambrook Smith, G.H. (2018) Abundance, Distribution, and Drivers of Microplastic Contamination in Urban River Environments. Water 10(11), 1597; doi:10.3390/w10111597

Nel, H.A., Dalu, T., Wasserman, R.J., Hean, J.W. (2019) Colour and size influences plastic microbead underestimation, regardless of sediment grain size. Science of The Total Environment 655: 567 ̶ 570.

Nel, H.A. & Froneman, P.W. (2018) Presence of microplastics in the tube structure of the reef-building polychaete, Gunnarea gaimardi (Quatrefages 1848). African Journal of Marine Science 40: 87 ̶ 89.

Nel, H.A., Dalu, T. & Wasserman, R. (2018) Sinks and sources: assessing microplastic abundance in river sediment and deposit feeders in an Austral urban river system. Science of the Total Environment. DOI: 10.1016/j.scitotenv.2017.08.298.

Nel, H.A., Hean, J.W., Siwe Noundou, X., Froneman, P.W. (2017) Do microplastic loads reflect the population demographics along the southern African coastline? Marine Pollution Bulletin 115: 115  ̶ 119.

Nel, H.A. & Froneman, P.W. (2015) A quantitative analysis of microplastic pollution along the south-eastern coastline of South Africa. Marine Pollution Bulletin 101: 274 – 279.

Project contacts:

• Professor Stefan Krause, University of Birmingham (PI)
• Professor Iseult Lynch, University of Birmingham (CoI)
• Professor Greg Sambrook-Smith, University of Birmingham (CoI)

Work Packages contacts:

• Work Package 1: Dr Holly Nel
• Work Package 2: Dr Holly Nel
• Work Package 3: To be confirmed
• Work Package 4: Anna Kukkola