Multimodal characterisation of nanomaterials in the environment

Lead Research Organisation: Imperial College London
Department Name: Materials


Engineered nanomaterials (ENMs) are found in many consumer products including cosmetics and personal hygiene goods. Nanomaterials are also found in additives for diesel fuels to improve fuel efficiency. These materials will come into contact with the environment, for example, if they are washed down the sink, or if they become airbourne, however we currently have no idea about whether they are hazardous or not and regulations are not in place to control their release or treatment. The life cycle of ENMs in the environment is not known and there exist large knowledge gaps in this field. The reason for this is that the concentrations and properties of ENMs in consumer products are largely unknown (or not indicated by companies). Very little is known about the behaviour or lifetime of ENMs in the water effluent and soils as it's extremely hard to monitor this behaviour, as we do not have the tools to detect these tiny materials in very complex environments. This project will apply new and sophisticated experimental characterization tools for predicting potential environmental risks associated with the use of selected consumer products incorporating ZnO, Ag, TiO2 and CeO2 ENMs. An overarching goal is to evaluate which are the critical charateristics of ENMs (size, chemistry etc.) which may cause damage to the environment through two of the most predominant environmental pathways - from the effluent of a waste water treatment plant to waters and also from sewage sludge to soils. This information will ultimately to provide guidance to regulators on policy and to industry about how to design "safe" classes of ENMs and mitigate against risk, while avoiding overregulation. Avoiding overregulation is vital, as we do not want to re-experience what happened e.g. at Fukushima, where 160,000 people were forced to relocated without need, since the risk presented to regulators and the government was too high. This has since resulted in 1,599 deaths, as the displaced residents are suffering from health problems, alcoholism and high rates of suicide.
Our team has an extensive track record in developing unique techniques to track these nanomaterials in complex environments and will apply their knowledge of this field to tackle this extremely pertinent concern. The projects experimental approaches include both physical science experiments and toxicological approaches, generating results to improve our limited understanding of the potential environmental hazards. The results generated from the project will also contribute to our very limited knowledge on various aspects of the fate, transport, bioavailability, and ecotoxicity of ENMs and will allow us to answer questions such as "can toxic doses of ENMs reach organisms or are these concentrations negligible at the point of exposure to the organism?", "if they are toxic, is it possible to re-engineer ENMs such that they do not present a risk", "do the nanomaterials dissolve or change their chemistry in the environment and ultimately detoxify and how does this vary between the different nanomaterials?", "which nanomaterials present the greatest risk and how do we minimise the environmental and health risks of these hazardous materials without overly precautionary regulations". This multifaceted strategy will make a major development in understanding the fate of ENMs in the environment to guide policy regulation whilst avoiding unnecessary overregulation, and ultimately guide the safe development of these materials for future commercial exploitation.

Planned Impact

With increasing commercialisation and up-scaling of silver, zinc oxide, ceria and titania nanomaterials production, comes a concomitant need to understand occupational health, public safety and environmental implications of these materials. Due to the enormous number of permutations of nanoparticles shape, dimensions, composition, and surface chemistry, only a fundamental understanding of the critical processes will allow a realistic, practical assessment of the risks of wide range of possible products. The proposed work will impact on ENM development by establishing the relative environmental risk associated with different classes of ENMs. By establishing the potential of each classes of ENM for any environmental risks, suitable precautionary measures can be identified. At the moment, the uncertainty surrounding ENM safety is a major barrier to commercial development. By establishing a higher level of confidence about safe handling of these classes of ENM, this project will have a major economic impact. Nanoscale studies of the complex environment-nano interface lie at the heart of technical challenges. Despite numerous reports, there is no consensus regarding environmental toxicity enacted by these nanomaterials due to a lack of understanding of their lifecycle in the environment. This project will make a step-change in our understanding of the fate of these nanomaterials and their ultimate bioreactivity with organisms. The following groups will benefit:
a. ENM manufacturers and their customers: Businesses will be able to make informed decisions about which technologies to pursue. Alternatively, they will be able to select effective safety measures or potentially redesign their products to avoid any potential hazards.
b. Government, society and policy makers: The Environment Agency and the Department for the Environment, Food and Rural Affairs will benefit from insight to any hazards associated with these classes of ENMs to recommend on policy and regulations to ensure safe handling in the workplace and the environment. The health and safety executive has been working hard recently to provide appropriate and balanced advice to companies working in the area; the outputs of this project will help them to refine their advice. The Royal Commission on Environmental Pollution and Royal Society are actively involved with public engagement in the field of environmental and nanotoxicology and will also benefit from this research which will feed into reports, commissions and recommendations made by these and similar societies.
c. Society: Clearly, workers in the ENM and water industries need to be protected adequately from any potential risks whilst maximizing their productivity; only with a detailed understanding of ENM toxicology, can appropriate control measures be selected. More generally, the public will benefit from the safe development and commercialisation of ENM technologies.
d. Instrument manufacturers and service providers will benefit from the development of new in situ techniques for tracking nanomaterials in complex environments, allowing them to expand their markets.
e. Improved training for early career researchers: A significant impact of this grant will be generation of highly trained PDRAs people in advanced materials characterisation and environmental science. There is a lack of skilled people in these interdisciplinary areas.
f. Timescale for benefits to be realized: In the short-term any general conclusions about ENM safety are likely to have a relatively rapid impact on health and safety policy. In the longer term, these results may contribute to an understanding of the environmental significance, if any, of ENM structure.


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Ruggero F (2021) A highly efficient multi-step methodology for the quantification of micro-(bio)plastics in sludge. in Waste management & research : the journal of the International Solid Wastes and Public Cleansing Association, ISWA

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Voulvoulis N (2018) Water reuse from a circular economy perspective and potential risks from an unregulated approach in Current Opinion in Environmental Science & Health

Description 1. Transformations of zinc oxide nanomaterials sewage waters and primary sewage sludge. We have developed an applied a new in situ microscopy technique to study the real-time speciation of ZnO nanomaterials at the nanometer scale in: i) influent water collected from Cambridge waste water treatment plant (WWTP) and ii) humic acid solution acidified to simulate a simplified primary sludge environment and iii) primary sludge. We found that a complete transformation of isolated ZnO nanorods into ZnS occur after only 1-hour in influent water, but larger aggregates of the ZnO nanorods transform only partially, with small contributions of ZnS and Zn-phosphate Zn3(PO4)2 species, after 3 hours. Transformation of aggregates of the ZnO nanorods towards mixed ZnS, Zn adsorbed to Fe-oxyhydroxides, and a large contribution of Zn3(PO4)2 phases are observed during their incubation in primary sludge for 3 hours. Discrete, isolated ZnO regions are imaged with unprecedented spatial resolution, revealing their transformation towards Zn3(PO4)2. This work brings forward the importance of analyses at the scale of the particles, and the power of spatially resolved in situ nano-x-ray flourescence (XFM) to image the nanoscale chemistry of nanomaterial mixtures in highly complex, heterogeneous semisolid matrices, and identifies the species for subsequent assessment of their bioreactivity.

A paper on the technique development was accepted by ACS nano (IF 14) and in Advanced Sustainable Systems on transformations of ZnO NPs in real waste water sludges.
We have also studied the fates of zinc oxide nanoparticles (ZnO NPs) and ionic Zn at low, environmentally relevant concentrations, in a real primary sludge collected from a municipal wastewater system by stable isotope tracing. This work shows that at these concentrations, the ZnO NPs dissolve rapidly, behaving as ions and suggests that zinc ion toxicity is of more importance than previously thought, as highly mobile zinc ions can easily leach into the effluents (work published in Global Challenges, 2021).

2. Many researchers have quantified risks of nTiO¬2 on single freshwater algal species, however these tests have focussed on green algae in simulated laboratory experiments using model species that are not commonly recorded in the freshwater environment. We have shown evidence of significant changes, ranging from highly stimulatory to strong negative impacts in natural assemblages of phytoplankton and phytobenthos, at environmentally realistic concentrations and/or concentrations equating to hot spots of accumulation of the contaminant nTiO2 in river waters. Important factors determining outcome(s) from these experiments were related to exposure time to nTiO2, and the phase and concentration of nTiO2 adopted. We have also critically evaluated the technical challenges of working with mixed natural assemblages of phytoplankton and phytobenthos when using relatively insoluble nTiO2 particles and have generated guidelines to aid future design for toxicity testing of TiO2 nanoparticles. Paper accepted by Science of the Total Environment, March, 2022 and we have been invited to write a methods paper to be considered by Science of the Total Environment, IF 8. A Bristol MSc student passed their thesis on this topic in 2021.

3. CeO2 nanoparticles (NPs) have been used as diesel fuel additives, acting as fuel combustion catalysts, to increase fuel efficiency and reduce the emission of greenhouse gases. These materials will encounter fresh waters in the environment, where they can be washed into streams and rivers and the wider ecosystem. We have shown that CeO2 NPs damage fresh water Algae; some of the CeO2 NPs may adsorb to some algae. We have also shown that they can dissolve over short time scales. Interactions with the NPs or their dissolved products could lead to cell deformities such as plasmolysis and other disfigurements. We found that interactions of the NPs with algae may depend on light conditions during aging. We are writing up this work for publication to Environmental Pollution IF 8.

4. Commercial Zn nanoparticles: Chlorophyll a fluorescence was used to examine the photosynthetic response of the algal species Raphidocelis subspicata and the benthic diatom Nitzschia palea to different types of zinc oxide nanoparticles. We observed a rapid negative impact in the maximum electron transport rate in samples exposed to zinc oxide and fully sulphidised nanoparticles but no measurable impact of partially suphidised NP's, indicating that release of sulphidised forms of ZnO NP's would likely not be toxic to autotrophs. The rapid response likely results from zinc dissolution and intracellular uptake of zinc ions, leading to damage to walls and membranes. Questions that we are addressing include: Are generation reactive oxygen species (ROS) generated in the cells? What are the impacts on single cells and natural assemblages? We showed that the motile benthic diatom species may be less impacted than other species as the carbohydrates they release may adsorb metal ions. A Bristol MSc student passed her MSc thesis on this topic of impacts of ZnONPs on benthic diatoms and she has obtained a job working for a company working, on removal of contaminants using algae.

4. Bioreactivity of AgNPs to freshwater algae. Commercial Ag NPs (20 nm) were incubated in R. subcapitata (green) algae under controlled conditions (T, illumination (white and UV)) and the structure of the AgNP-exposed algae was compared to that of the control algae (no AgNPs). A novel suite of photobioreactors have been set up in a temperature-controlled growth room for determination of toxicity of NPs on algae with options for quantification of impacts in both planktonic and benthic modes. The facility allows for quantification of UV impacts in addition to visible light. A selection of media has been trailed to optimise quantification of impacts of NPs whilst avoiding confounding issues of pH and precipitation of test ions, following dissolution of NP's. Data on the bioreactivity of AgNPs (20 nm) on the ISO standard species Raphidocelis subcapitata has been measured. No significant toxicity was recorded for concentrations of AgNPs in the range 0.5 to 500 µg l-1, measured after a 24 hour exposure period, but thereafter, a rapid decline in photosynthetic performance was measured with a circa. Using very high-resolution electron microscopy techniques, we have shown that the AgNPs are not internalised by the algae but instead are captured by a layer of extracellular protein which appears to be protective. Key findings include: 1. The Ag NPs had transformed to a sulfide when they came in contact with the algae; 2. Some Ag NPs came in contact with the cell wall of the algae, and there is evidence of dissolution; 3. The subcellular structure distribution of the algae was significantly modified as a consequence of exposure to the Ag NPs and first evidence that the AgNPs can be internalised. A PhD student was awarded her thesis for this work in March, 2020.
Exploitation Route Our research will be taken forward using the following academic and non-academic routes:
1) Society: A particle impactor has been purchased (California Instruments) to assess nanoscale pollutants in ambient air. The impactor draws air through three chambers, each housing a SEM stub. After a set period (determined by experimentation), the SEM stubs will be assessed using SEM with EDX. The impactor will be placed in various locations in the South West. This will allow us to assess whether air is a potential pathway for ENMs (such as the diesel additive CeO2) to reach human receptors. As part of this work, a collaboration with the Meteorological Research Institute, Japan Meteorological Agency - world experts in airborne nanoparticle capture and characterisation is being arranged.
2) Society and academia: In June 2017, the Bristol contingent of the team made a research visit to the Meteorological Research Institute (MRI) in Tsukuba, Japan to exchange samples, research ideas and best practice in relation to the capture and analysis of aerosol ENMs (CeO2, FeOx) from vehicle pollution. This was the start of a collaboration with Prof Yashuioto Igarashi, the MRI lead expert on airborne nanopollution.
3) We presented the results of our work at the UK nanomaterials regulators meeting in November 2017 and set up a new collaboration with the CEH, Oxford. We are now collaborating on a PhD studentship together funded by an EPSRC CDT.
4) The microscopy techniques developed through the project are being used to image the interaction of airborne pollution with lung cells (in collaboration with the Royal Brompton Hospital, London).
Sectors Chemicals,Energy,Environment,Healthcare,Government, Democracy and Justice,Pharmaceuticals and Medical Biotechnology,Transport

Description The PI presented work on the environmental impacts of engineered nanomaterials at the Huxley Summit, at the Royal Institution in December, 2019 to a panel of scientists and the public.
Sector Environment
Impact Types Societal

Description Assessing the risks of 2D nanomaterials in the environment
Amount £50,000 (GBP)
Organisation Lloyd's Register 
Sector Charity/Non Profit
Country United Kingdom
Start 10/2017 
End 09/2021
Description Health assessment across biological length scales for personal pollution exposure and its mitigation (INHALE)
Amount £2,793,915 (GBP)
Funding ID EP/T003189/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 04/2019 
End 03/2022
Description STFC Batteries Early Career Award
Amount £1,900 (GBP)
Organisation Science and Technologies Facilities Council (STFC) 
Sector Public
Country United Kingdom
Start 12/2016 
End 06/2017
Description Anglian Water 
Organisation Anglian Water Services
Country United Kingdom 
Sector Private 
PI Contribution We performed state of the art characterisation of nanomaterials in environmental media from taken from different stages of a waste water treatment plant.
Collaborator Contribution Anglian Water provided us with water, sludge, and soils sample from different stages of treatment and different sites in the waste water treatment plants from identified nanomaterials hotspots.
Impact Yes. One paper under review in a journal.
Start Year 2006
Description British Geographical Society 
Organisation British Geological Survey
Country United Kingdom 
Sector Academic/University 
PI Contribution We have found expertise within the BGS and are now having input from them in relation to identifying a number of possible pollution hotspot sites.
Collaborator Contribution Two hydrochemists at the BGS have agreed to sit on our steering committee.
Impact None
Start Year 2016
Description Characterisation of engineered nanoparticle impacted sewage waters 
Organisation University of Birmingham
Country United Kingdom 
Sector Academic/University 
PI Contribution The objective was to quantify the lifetime and characterise the physiochemical characteristics of engineered nanomaterials (ENMs) as they reach the environment through wastewater treatment plants (WWTP), specifically as they partition between 1) water, wastewater, sludge and soil and 2) effluent and freshwater. The nanomaterials of interest were CeO2, ZnO, TiO2 and Ag. We worked with the FENAC facility in Birmingham to perform field flow fractionation (FFF) to isolate the nano-scale (~100 nm) portion of the samples of engineered nanomaterials in soils and sediments. We also performed single particle ICP-MS to detect the particles within these media. We provided samples and scientific questions.
Collaborator Contribution They supplied instrumentation (FFF) and single particle ICP-MS facilities.
Impact None yet.
Start Year 2017
Description Collaboration with Polymateria, via a PhD studentship 
Organisation Polymateria Ltd
Country United Kingdom 
Sector Private 
PI Contribution PhD supervision and equipment.
Collaborator Contribution Scientific advice, materials and access to equipment.
Impact None yet.
Start Year 2019
Description An invited talk 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Angela Goode gave an invited talk on correlative in situ microscopy of nanomaterials in environmental media at the organic-inorganic interfaces meeting held by the Royal Microscopical society. The talk sparked discussions with instrument manufacturers to develop our research on this topic. A large EPSRC EP/V007661/1 (~ £10M) grant was funded in 2020 to develop correlative electron microscopy techniques (AEP and MPR are co-Is).
Year(s) Of Engagement Activity 2018
Description Invited Talk 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Third sector organisations
Results and Impact Webinar on the impacts of micro and nanoparticles on the environment to Imperial University. This sparked a discussion afterwards with chemists.
Year(s) Of Engagement Activity 2020
Description Invited Talk 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Postgraduate students
Results and Impact Research debate on the risks of nanomaterials to human health and the environment.
Year(s) Of Engagement Activity 2019
Description Seminar Invited 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact The PI gave a talk on correlated imaging of nanomaterials in complex environments. She set up a collaboration with an expert in in situ TEM which arose from this meeting.
Year(s) Of Engagement Activity 2018
Description Talk on Multimodal characterisation of nanomaterials in the environment Prof. Tom Scott, Bristol 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Prof. Tom Scott gave a presentation on our project to the MRI, Japan in October 2017.
Year(s) Of Engagement Activity 2016