Millions of people in sub-Saharan Africa rely on hand-pumped boreholes (HPBs) for their water supply, but they are often unreliable, with frequent breakdowns and long repair times. Although there have been previous attempts to understand the difficulty of access to water in rural areas and the functionality of rural water supply systems, they have typically taken ‘siloed’ approaches and focused only on the technical or social factors that influence the supplies’ performance.

A and local researchers in both Africa and the UK, shows that the failure of HPBs is not simply due to a single issue, such as a lack of water or a technical failure: it is the result of a combination of complex social, technical and physical interactions. The study provides crucial information for decision makers across governments, non-governmental organisations (NGOs) and communities aiming to make rural water access more reliable.

The research found that the probability of any failure occurring is dominated by physical and engineering factors: a combination of water levels, the condition of the pump, aquifer yields, and borehole construction and configuration. The length of time the pump was out of action was dominated by social factors including demand, access to spare parts and financing. The project team, led by BGS, tested current HPBs and facilitated interviews and participatory mapping events with water users and managers across Ethiopia, Malawi and Uganda. Combining statistical patterns of HPB failure with lived community experiences led to a new conceptual model that represents the diversity of real-world water-management arrangements.

This paper invites those working in rural water supply in sub-Saharan Africa to consider infrastructure performance through an interdisciplinary lens. These complex interactions can be understood by using frameworks like the one proposed in this study to improve rural water supply performance, which is especially important as rural water systems evolve towards more complex solar and piped technologies.

It hoped that understanding these complex interactions around rural water supplies will help governments, NGOs and communities make rural water access more reliable and fairer for all.

Dr Donald John MacAllister, BGS Senior Hydrogeologist the paper lead author

This research provides valuable insights into the interconnected drivers of water service downtime. Its findings come at a critical time as groundwater will continue to play a central role in meeting future water demand and strengthening drought resilience. Acting on these insights will be essential to enhance public and private sector support for water service provision through stronger regulation, improved planning, increased financing and enhanced service management.

Vincent Casey, WaterAid

The paper is now available online:

A new guide to Zambia critical minerals highlighting the country current and potential critical mineral resources, including cobalt and lithium, was launched this week in Lusaka. ‘’, now available to read online, came about through a collaborative effort between the Zambian Ministry of Mines and Minerals Development and the 51ÁÔÆæ (BGS). Funded by the Foreign & Commonwealth Development Office and BGS International Geoscience Research and Development programme, the guide provides a strong example of how the UK/Zambia partnership is underpinned by an institutional exchange of expertise that supports both nations’ priorities.

Critical minerals are essential to the global energy transition. Diversifying their associated supply chains is central to improving their resilience to global economic fluctuations. Over the past few years, Zambia has boosted its critical mineral economy through increased production of manganese and nickel. In 2024, the Zambian government announced a national strategy to more than triple its copper production to 3 million metric tonnes annually by 2031. The country is also set to open Africa first cobalt sulfate refinery by the end of 2025, a major milestone in diversifying the global supply chain and a move that could be a crucial moment in both Zambia and Africa mineral valorisation efforts. The facility will be one of the few outside China capable of producing cobalt sulfate, which is a key component in the lithium-ion batteries that power smartphones, computers and electric vehicles.

Zambia has a 100-year history of providing the copper that has helped to electrify the world. The ‘Critical minerals potential of Zambia’ guide, co-produced by the Zambian Geological Survey Department and BGS, will help to kick start the next chapter in the economic development of the Zambian economy. The lithium, graphite, cobalt and other critical mineral resources of Zambia are sorely needed to decarbonise global power generation and storage.

As a geologist, I have worked on Zambian mineral resources for over 35 years and am proud to continue playing a small part in supporting Zambia to develop as an emerging economy that will bring prosperity and improved life chances for all Zambians.

Clive Mitchell, BGS Project Leader, critical minerals resources — Zambia.

As the world transitions to a low-carbon future, Zambia stands ready to play a vital role by responsibly developing our critical mineral resources. Containing up-to-date insights into the geology, production and exploration of eleven minerals deemed essential to Zambia future prosperity and the world clean energy ambitions, this publication provides valuable information for investors, policymakers and researchers alike.

Gerald Mwila, director of the Geological Survey Department, Zambia.

The ‘Critical mineral potential of Zambia’ guide will support Zambia transition to one of Africa most significant critical mineral producers. It presents for the first time the geological occurrences, exploration efforts and mineral production statistics for critical minerals in Zambia, both current and into the future.

The guide focuses on eleven minerals identified as ‘critical’ by the Zambian Ministry of Mines and Minerals Development critical minerals strategy:

• cobalt
• columbite-tantalite
• copper
• graphite
• lithium
• manganese
• nickel
• rare earth elements
• sugilite
• tin
• uranium

Driven by the electric vehicle and portable battery sectors, global demand for graphite and lithium may increase by as much as 130 and 350 times by 2040, respectively. Zambia possesses some of the world highest-grade deposits for copper and is the seventh largest copper-producing country in the world. The country also produces nickel, the global demand for which is set to increase by almost 70 per cent between 2024 and 2040. Cobalt is considered a critical mineral by the UK and USA, and as a ‘strategic’ mineral by the EU.

The guide was launched on 16 July by Calvin Bailey MBE MP, the UK trade envoy for southern Africa, alongside British High Commissioner to Zambia Rebecca Terzeon at the Invest-Zambia International Conference 2025.

I was delighted to announce the 51ÁÔÆæ’s new guide to critical minerals in Zambia. This will support Zambia National Critical Minerals Strategy and will help attract responsible investment in the minerals sector, supporting economic growth and the global green energy transition.

Calvin Bailey MBE MP, UK trade envoy for southern Africa.

The work of the 51ÁÔÆæ together with Zambia is an excellent example of the collaboration under the UK/Zambia partnership, which brings economic and environmental benefits to both countries. This is one of many examples of our two countries working together to achieve our shared priorities for economic growth and green energy transition.

Rebecca Terzeon, British High Commissioner to Zambia.

The guide highlights the geology, exploration, occurrences and mineral production of the eleven critical minerals. Knowledge of critical minerals is not just important for geologists and mineral exploration companies; it also educates decision makers and regulators in government and the wider public when they encounter mineral developments in their communities.

Since joining BGS in 2022, my time spent working alongside the Zambian Geological Survey Department has been a highlight. We have collaborated in Eastern Province, focusing on graphite reconnaissance fieldwork, and in Lusaka, working on the critical minerals guide. Zambia is home to such friendly, welcoming and environmentally conscious people and we hope this guide attracts interest from Zambian and international investors alike.

Dr David Currie, BGS Minerals Scientist.

This guide is part of a mineral ecosystem that aims to diversify the Zambian mineral production portfolio and bolster the resilience of the Zambian economy. Mineral promotion, such as this guide, reveals information on mineral resources that exploration companies may not have come across and potentially leads to investment in Zambia that could ultimately result in development of mines and mineral production.

For more information, please contact 51ÁÔÆæ press (bgspress@bgs.ac.uk) or call 07790 607 010.

They presented their findings at a stakeholder workshop in Kisumu at the Kenya Marine Fisheries Research Institute (KMFRI). Stakeholders were gathered from academia, research institutes and government, along with community representatives and they were all invited to share their experiences in land and lake management.ÌýÌý

Changes to Kenyan land-management practices are urgently needed for sustainable agricultural productivity and to reduce the growing problem of soil erosion and transfers into Lake Victoria, which compromise the growing economic and food security dependence on fisheries aquaculture. The goal of the workshop was to find a way to better coordinate disparate research and create partnerships to improve communications that will better inform land-management decision makers. 

The workshop 

The workshop covered three exercises across three groups, with the first two set up as ice breakers and to help participants consider how they could translate research findings into impact. These exercises directed discussion towards the preparation of policy briefs: what they are, who reads them and how they can be effective, alongside examples of community engagement to change behaviour or practice.  

The third exercise generated the most discussion on how data and research should be coordinated and shared, with examples of good practice being quite rare owing to a lack of resources and expertise. Additionally, the exercise discussed whether there could be a process to enforce the delivery of research harmonisation, improved reliability of data quality and the ability to consider multiple research outcomes from numerous projects. Again, examples of good practice were limited, although less direct means of communication to policy decision makers were discussed; for example, via media or a community bottom-up approach.Ìý

Overall, the workshop demonstrated that the key to enabling a positive change in behaviour and practice for land and lake management is ensuring community engagement from the outset of a research project, such as engaging with focus groups, having community representatives or enabling citizen science participation. The workshop participants agreed that a committee was essential to share research outputs with relevant stakeholders in the Lake Victoria basin. A virtual platform is also essential to a functional framework, so that research outcomes are better shared, data is used in multiple ways to realise efficiency gains and long-lasting impact is created from research. However, such a platform would require adequate resourcing and continued support from stakeholders, alongside engagement from policy decision makers.  

Joint research with the University of Eldoret and KMFRI 

Research shared with this group was funded via previous Royal Society and NERC grants. It initially involved mapping the geochemistry across the Winam Gulf catchment of the Lake Victoria basin, to model the areas at greatest risk of soil erosion and identify more precisely the locations within a river catchment suitable for targeting limited resources to train farmers and test intervention methods to reduce soil erosion.  

Secondly, sediments and sediment cores were surveyed across the Winam Gulf catchment, to generate a chronology of sediment run-off over the past 100 years, as well as the extent of metal and nutrient land-to-lake transfers. This will help us to better understand the effects of poor land management on the lake environment.  

Field collections, measurements, and digitisation and modelling of data were described in previous blogs, with partnerships cemented by the exchange of technicians, early career researchers and principal researchers. The opportunities created by this collaborative project collectively and individually demonstrate the potential for scientific research to address environmental issues whilst developing scientific capacity in Kenya and the UK. The two-way exchange of staff and paired UK/Kenya PhD students provided an enriching experience for all involved. 

Continuing partnerships  

Ongoing efforts will see improvements to modelling the risk associated with soil erosion, including translating a machine-learning model for predicting risk at the sub-catchment scale to other similar land-lake environments, to determine changes in soil losses/sediment transfer at historical scales (100 years) and through dynamic modelling (within few years). Funding to support an advisory forum for Lake Victoria has the potential to set a template for the region on how to better coordinate research data. This will be of particular value to developments in machine learning, which can analyse vast amounts of data quickly. Machine learning could provide a broader, more effective perspective beyond the typical scope of a research project but is dependent on harmonised approaches to data capture and quality. 

Data and information are very expensive due to their endless nature and the value attached to them; thus, quality collaboration between KMFRI, BGS and UoE has created a unique platform to provide baseline and useful data and information on lake-land interphase, which will form the foundation of lake-basin management, planning and conservation in the region. 

Data and information are very expensive due to their endless nature and the value attached to them; thus, quality collaboration between KMFRI, BGS and UoE has created a unique platform to provide baseline and useful data and information on lake-land interphase, which will form the foundation of lake-basin management, planning and conservation in the region. 

Acknowledgements 

We would like to thank: 

• Olivier Humphrey and Andy Marriot, who provided expertise in machine learning, and sampling strategy and fisheries, respectively (BGS)Ìý

• Job Isaboke and Sophia Dowell, joint UK/Kenya PhD studentsÌý

• Staff from all three institutes that supported laboratory and field work, logistical arrangements and community engagementÌý

• Collins Ongore, Job Mwamburi and George Basweti (KMFRI)ÌýÌý

• Elliott Hamilton and Amanda Gardner (BGS)Ìý

• Prof William Blake for guidance on soil erosion sampling strategy and translation of data outcomes into useful data tools to advise on land management (University of Plymouth).Ìý

Funding 

This work was financially supported by:  

• Natural Environment Research Council (grant numbers NE/R000069/1, NE/X006255/1, NE/S007334/1 and GA/19S/017)Ìý

• Royal Society (grant number ICA/R1/191077])Ìý

• British Academy (grant number WW21100104] )Ìý

• Commonwealth Scholarship Council UK for professional fellowshipsÌýÌý

About the authors 

Dr Christopher M Aura: Director of Freshwater Research at the Kenya Marine Fisheries Research Institute. Chris was a co-PI on the joint research, with oversight on the lake management, sampling and community engagement. 

Prof. Odipo Osano: Professor of Environmental Sciences at the University of Eldoret.  Odipo was a co-PI on the joint research, with oversight on the land sampling and community engagement, overall coordination of Kenyan activities. 

Dr Michael Watts: Head of Inorganic Geochemistry and Lead for International Geoscience R&D at BGS.  Michael was the PI for UK funded grants and overall coordinator for the project. 

51ÁÔÆæ has been working to reduce the global impact of sand mining through its International Geoscience Research and Development (IGRD) programme. After a successful trip to Malaysia in early 2023 and development of good practice guidance, the BGS team was keen to work alongside international partners in countries where sand mining and supply has become a major national issue. ÌýÌý

In the autumn of 2022, Alieu Jawo, the director of the Geological Department of The Gambia, visited BGS to discuss the acute shortage of sand faced by his country. As is the case for many countries going through a construction boom, shortages of sand are causing numerous problems, including: Ìý

• increased levels of illegal mining 

• damage to fragile environments  

• delays to construction of new buildings and infrastructure   
  

Ultimately, shortages of sand are negatively affecting national economic development. Could this be an ideal opportunity to understand if the tools BGS is developing could be usefully applied in the field?   

We certainly thought so and our gracious hosts at the Geological Department in The Gambia quickly put us to work training their staff in geological fieldwork techniques for mapping sand resources. This was my first time in west Africa and, away from the breeze of the coast, the heat of the midday sun and high humidity made working an exercise in finding shade. I couldn’t decide whether this was better or worse than my usual environment of muddy Yorkshire fields in the rain…   

Sand supply

It was very apparent that sand supply is a critical issue in The Gambia. Due to an increasingly urban population, there is a burgeoning construction industry and a pressing need for new roads and infrastructure. This is driving a huge demand for construction materials, principally sand — a demand that has become impossible to deliver sustainably using traditional sources. There is a real need for better understanding of the geology and environmental processes to help find new sand resources and understand what the effects of extraction might be.  

During two weeks of field visits and discussions with government, policymakers and industry, we obtained an in-depth understanding of the huge amounts of damage caused by the resource demands of a rapidly developing nation combined with a legacy of poor controls on extraction. We visited vast swathes of what used to be pristine coastal dunes that have been reduced to low-lying swamps by over-extraction of sand. Whilst being driven between field sites, we passed truck after truck loaded with sand and crushed lateritic soil. Almost every house seemed to have a pile of sand outside, reminding us of how important supply was at both a national and local levels.

Despite the obvious challenges being faced by The Gambia, there are plenty of reasons for optimism. The enthusiasm of the staff at the Geological Department for using geoscience to help the country develop was contagious. There are already identified improvements that could be made on managing mineral resources, such as development of better geological data and models, as well as straightforward actions for the industry, like processing the sand to so it can be used for higher-value applications such as concrete, as opposed to fill material.

Marine sands 

The Gambia also faces significant risks though its race to develop. Marine dredging is seen by many as the solution to sand shortages in the country.  Whilst marine sands can certainly be an important and low-impact source for construction material, without detailed understanding of marine geology, hydrography and biology it also has the potential to cause significant negative environmental effects.  

Luckily this is something we do very well in the UK and we were able to pass a lot of accepted good practice (for example, that published by the ) to industry and government representatives during our visit. It has also given the BGS team lots of good ideas as to how we can develop better tools and share knowledge to help countries like The Gambia continue to access the raw materials essential for development in a sustainable way.

About the authors

Collaboration can provide an exchange of information vital to the advancement of environmental research. One such partnership is the relationship between BGS and the University of Eldoret (UoE) in Kenya. This partnership not only demonstrates the benefits of international collaboration but also highlights the importance of addressing global challenges collectively.  

Job Isaboke (UoE) and Sophia Dowell (BGS) are research students at their institutions and have been to measure the rate of soil erosion in western Kenya using novel chemical methods. For their PhD projects, they aimed to understand the effect land management can have on soil erosion using plutonium isotopes (Sophia) and the associated loss of micronutrients from the soil (Job), which is important for crop composition and onward dietary intake for animal and human health.

Soil erosion  

Soil erosion is a widespread environmental issue that poses a significant threat to agricultural productivity, water quality and ecosystem health worldwide. In Kenya, soil erosion is driven by factors such as deforestation, unsustainable land-management practices and climate change. However, quantitative data describing the amounts and patterns of soil erosion and sedimentation can be used to inform sustainable soil conservation practices. This data can also aid in the validation of predictive models for an improved understanding of factors influencing the acceleration of erosion processes.ÌýÌý

Working together 

One of the primary advantages of international cooperation is the sharing of expertise and resources. Bringing together diverse backgrounds benefits research at both BGS and UoE by combining advanced technologies and methodologies, such as specialist mass spectrometry methods to detect ultra-trace plutonium in the UK, with invaluable local knowledge and on-the-ground insights from Kenyan counterparts. This allows for a more comprehensive approach to studying soil erosion, encompassing both scientific rigour and practical applicability.  

Ultimately, the collaboration between BGS and UoE stands as a key step toward securing the sustainable future of this agriculturally crucial region and works towards addressing several of the , including: 

• poverty (SDG 1) 
• life below water (SDG 14) 
• life on land (SDG 15)  
  

Beyond scientific advancements, working together to research soil erosion fosters cultural exchange and capacity building. Through joint research initiatives, Job and Sophia have been able to learn from each others’ perspectives, approaches to research and experiences. This cultural exchange has not only enhanced both their roles as early-career researchers, but has also strengthened relationships between BGS and UoE to promote mutual understanding.  

The international collaboration also contributes to the development of scientific capacity in Kenya. By providing training opportunities, mentorship, networks and technology transfer for members of both UK and Kenyan institutions, early-career researchers are empowered to tackle environmental challenges independently.

The opportunities created by this collaborative project collectively and individually demonstrate the potential for scientific research to address environmental issues whilst developing scientific capacity in Kenya and the UK. The two-way exchange of staff and paired Kenya/UK PhD students, including Job and Sophia, provided an enriching experience for all involved.

Michael Watts, head of the BGS International Geoscience Research and Development programme

So much can be achieved with collaboration and a working international team breaks much more than just academic barriers. The larger body of knowledge would benefit through building collaborations globally, as this work has demonstrated.

Prof Odipo Osano, University of Eldoret, Kenya

Through this partnership, Sophia and Job are working towards informing evidence-based decision making and developing targeted interventions to mitigate against future soil erosion. Through attending workshops and conferences, they have both had the opportunity to engage with stakeholders ranging from policymakers and land managers to farmers and community leaders. These workshops have allowed them to understand the best way to communicate their research to different stakeholders and further their understanding of the usability of the data, working on ways to target future research to ensure the maximum impact.  

Through fostering dialogue and knowledge exchange, the collaboration works towards the eventual adoption of sustainable land-management practices and helps to adopt agricultural practices aimed at preserving soil health and preventing erosion. 

I feel my PhD research wouldn’t have been possible without the support from Kenyan counterparts at the University of Eldoret. Both Job and Prof Odipo Osano in-depth knowledge of the local area and dedication to the research have been invaluable. Without their help, the fieldwork wouldn’t have been possible, especially during the COVID-19 pandemic where I wasn’t able to travel to Kenya to conduct the work myself. But, above all else, I feel this PhD opportunity has allowed me to grow, both professionally and personally, into the scientist I am today and for that I am extremely grateful.

Dr Sophia Dowell

As part of the collaboration, Sophia recently gained her PhD in ‘Utilising plutonium isotopes to evaluate soil erosion in tropical East African agri-systems’ and Job has gained a master degree in environmental science; he is now working towards his PhD in ‘Dynamics of soil micronutrient loss and transfer as influenced by land management’. 

As a PhD student from Kenya, I am grateful for the collaboration between UoE and BGS, which provided me with both laboratory training and financial resources. I appreciate the support from my UK supervisors, Dr Michael Watts and Dr Olivier Humphrey, and the entire BGS inorganic chemistry department team.

To be a successful scientist, one must undergo extensive training using advanced instrumentation and learn laboratory etiquette. Within the framework of my PhD research, I am currently working with Dr Sophia Dowell to determine soil erosion dynamics in tropical locations and link this to micronutrients in soils.

Job Isaboke

Acknowledgements  

This research was conducted with the financial support of the following funders:  

• 51ÁÔÆæ/NERC grant NE/R000069/1, entitled ‘Geoscience for Sustainable Futures’  
• 51ÁÔÆæ Centre for Environmental Geochemistry programmes 
• NERC National Capability International Geoscience programme, entitled ‘Geoscience to tackle global environmental challenges’ (NE/X006255/1)  

Additional financial support from:  

• The Royal Society International Collaboration Awards 2019 grant ICA/R1/191077, entitled ‘Dynamics of environmental geochemistry and health in a lake-wide basin’ 
• Natural Environment Research Council ARIES Doctoral Training Partnership (grant number NE/S007334/1)  
• 51ÁÔÆæ University Funding Initiative (GA/19S/017)  

Additional support from:  

• British Academy Early Career Researchers Writing Skills Workshop (WW21100104) 

About the authors 

Sophia Dowell is an analytical geochemist working within the BGS Inorganic Geochemistry Facility in Keyworth. Prior to this, she was a BUFI PhD student funded by the NERC ARIES doctoral training programme. This PhD was in collaboration with BGS, the University of Plymouth and the University of Eldoret in Kenya. 

Job Isaboke is a PhD researcher funded by BUFI/The Royal Society in collaboration with BGS and the University of Eldoret. He has had the opportunity to work within the UK alongside BGS during his PhD but is mainly based in Eldoret, Kenya.  

In a world of rapidly developing technology, paper archives can often be overlooked as a vital first step in information gathering. Whilst custodians, librarians and records staff take great care in the arrangement and management of such archives, there is also an ongoing campaign against the idea of archives as ‘dusty’ and ‘forgotten about’. However, despite our best efforts, all archives can use a little TLC sometimes. Throw a subtropical climate and creepy crawlies into the mix and things can get very dusty! This was something I found out during a recent trip to the Zambian Geological Survey Department (GSD) in January 2024.  

Our work in the archives 

I travelled to Lusaka, along with BGS geo-information ingestion team coordinator Wayne Newham and minerals resource and security flows team leader Joseph Mankelow. as part of a project funded by the (FCDO) that aims to assist with the promotion of the critical mineral potential of Zambia. An important component of the project is to identify existing information on the mineral resources of Zambia available from the GSD, which can be used to understand the occurrence in the country of minerals required for the clean energy transition. A foundational step in building this capacity is the appraisal and organisation of the survey physical data, which was the focus of our trip.  

On arrival at the GSD, we met with the library and records staff and learnt more about the status of the archive. Together, we identified the most effective method for organising the paper records. Although the GSD holds a wealth of geoscientific data, including maps and aerial photographs, the focus of our visit was on mineral exploration reports dating from the 1920s to the present day. All we needed was a quick sweep, mop and to dust away some of the cobwebs and we were ready to go. 

Over the next two-and-a-half weeks, we populated a digital index, which captured vital metadata for each report and recorded its physical location in the archive. By creating this searchable index, GSD staff will have a fuller picture of the data they hold and library and record staff can now respond to enquiries from external stakeholders more promptly, enhancing their reputation as an authoritative repository of minerals information. 

Downtime in Zambia 

In the time not spent working at the GSD, we took the opportunity to sample the local cuisine including chikanda, a Zambian dish made from boiled root tubers; nshima, a maize flour porridge, and impwa (‘garden eggs’ in English), a vegetable similar to aubergine. We were also lucky enough to be in the country during the African Cup of Nations Football League (AFCON CUP 2024) and evenings were spent cheering on the national team with the passionate locals. Despite the fact Zambia didn’t make it past the group stages, nothing could dampen the fans’ spirits and goals were celebrated with much dancing and jubilation. I found out this positive and friendly attitude is ubiquitous throughout this welcoming south-central African country.  

What next 

The project team will return to Lusaka in February 2024 to continue the archive work and to hold a workshop that will bring together representatives from GSD, the Ministry of Mining and Minerals Development, and the mineral exploration sector to facilitate discussion on the potential for long-term critical raw minerals supply from Zambia.Ìý

About the author

Soil erosion processes present the greatest risk to land degradation worldwide and, due to fertile soil being an essential resource, there is increasing concern around the world regarding accelerated soil erosion, particularly in developing countries.

The analysis of plutonium (Pu) in soil samples can inform the understanding of soil erosion processes globally. However, there are specific challenges associated with such analysis in tropical soils, so an optimal analytical methodology that ensures the best sensitivity is critical.

Why use plutonium?

Due to their long retention times and minimal spatial variability, Pu isotopes have proven useful as an alternative fallout radionuclide tracer for determining soil erosion rates. To utilise Pu as an effective soil erosion tracer in the southern hemisphere, separation techniques and analyses need to be optimised to establish a robust analytical method for the determination of ultra-trace level Pu isotopes. This method must also have sufficient sensitivity for African soil samples, which typically have very low Pu concentrations compared to the northern hemisphere.

This research aimed to accurately establish fallout Pu activity concentrations in tropical soils in order to determine soil erosion rates with an improved separation and analysis method for ultra-trace Pu determination. To achieve this aim we had to:

• adapt and optimise a separation method using trialkyl methylammonium nitrate (TEVA) cartridges to remove matrix interferences with pre-concentration of ultra-trace Pu isotopes (this reduced waste and increased throughput)
• establish a robust analytical method for the determination of ultra-trace level Pu isotopes with sufficient sensitivity for African soil samples using oxygen as a reaction gas for inductively coupled plasma mass spectrometry (ICP-MS)

The development of robust analytical methods to determine rates of soil erosion and its effect on land degradation is vital to advise mitigation strategies, ultimately ensuring the future sustainability of soils.

Sophia Dowell, PhD student at BGS.

Where does the plutonium come from?

Pu is present in the environment primarily because of nuclear weapons testing. Between 1945 and 1980, 520 atmospheric tests were conducted worldwide; however, only 10 per cent of these experiments were conducted in the southern hemisphere. This resulted in significantly less fallout in the tropics than in the mid-latitudes of the northern hemisphere, which makes the analysis of ultra-trace Pu isotopes in tropical soils challenging.

The challenge of plutonium analysis

Due to their long retention time and minimal spatial variability, Pu isotopes have recently been used as an alternative fallout radionuclide tracer for determining soil erosion rates. As a result of the long half-lives of ²³⁹Pu and ²⁴⁰Pu (24 110 and 6561 years, respectively), approximately 99 per cent of the original activity remains in soils. This means they are suitable as stable, long-term tracers compared to, for example, 137 caesium (Cs), despite Cs’s significantly higher activity in the environment, as Cs only has a half-life of 30 years. Additionally, more than six times as many atoms of ²³⁹Pu and ²⁴⁰Pu were initially dispersed compared to ¹³⁷Cs. This combination of long half-life and higher atom content makes mass spectrometry (MS) techniques better suited to Pu isotopes, whereas radiometric decay counting techniques are more appropriate for the higher specific activity ¹³⁷Cs.

Consequently, recent developments in mass spectrometry techniques have the potential to increase the sensitivity of Pu isotope quantification and subsequently the availability of analytical methods applicable to tropical soils. This raises the potential of using Pu as a soil erosion tracer in the tropics, where the risk of soil degradation is increasing due to extreme weather patterns.

A powerful tool

This method presents a simple, cost-effective, robust sequence with reduced laboratory waste disposal, which is vital to ensure the separation method is applicable to low-resource laboratories. Along with the low detection limits that are comparable to alternative MS methods, this outcome makes the method applicable to the detection of ultra-trace fallout Pu in African soils.

Due to increasing concern regarding accelerated soil erosion and its impact on sustainable intensification of agriculture in developing countries, this work provides advancements in the detection of Pu. The new method is also a powerful tool for the analysis of ultra-trace Pu in African soils, ultimately improving the determination of soil erosion rates in tropical soils to better inform mitigation strategies.

This method has the potential to improve access to advanced soil erosion measurements that could be produced faster than traditional laboratory techniques to enable analyses at scale, yet with greater accuracy than machine learning predictions based on remote sensing data in developing countries which are most at risk to land degradation.

Sophia Dowell, PhD student at BGS.

Funding

51ÁÔÆæ led the research in conjunction with the University of Plymouth and the University of Eldoret in Kenya.

Sophia PhD was supported by the NERC funded ARIES doctoral training programme (grant number NE/S007334/1), and from the NERC International National Capability grants to BGS (NE/R000069/1 and NE/X006255/1), Royal Society International Collaboration grant (ICA/R1/191077), British Academy (WW21100104) and BGS University Funding Initiative (GA/19S/017).

More information

The full research paper is available: .

51ÁÔÆæ is collaborating with the University of Zimbabwe (UZ) in a study to assess access to clean drinking water sources across the city of Harare and the impact of recent donor-led upgrades to groundwater supply systems.

A fragile municipal water supply

Harare is Zimbabwe capital, with a population of approximately 1.5Ìýmillion in urban Harare and another 1.1Ìýmillion living in the satellite towns of Chitungwiza, Norton, Epworth and Ruwa ().Ìý

The city main drinking water source, Lake Chivero, its tributaries are heavily polluted by industrial waste and raw sewage inflows and the city drinking water treatment works are insufficient to supply Harare water demand.

Daina Mudimbu, geoscientist at ZIVA Data & Knowledge Management Consultants.

The water system was designed in the 1960s and produces approximately 704 megalitres (ML) of water per day against an estimated demand of between 800 ML to 1300 ML of daily water consumption (ZimFact, 2021).

Frequent outbreaks of waterborne disease

The response of the city water department has been to ration water, leading to an erratic piped water supply to communities that has been associated with a rise in outbreaks of waterborne diseases. In 2008 and 2009, Zimbabwe experienced one of the worst cholera outbreaks, resulting in the many deaths of mostly urban dwellers.

A city dependent on groundwater sources

The aged and inadequate infrastructure for water and waste-water treatment, increased drought and poor revenue collection from water surcharges on households have hampered the municipal water supply system, leading to greater dependence on groundwater.

Recurrent droughts of the 1980s and 1990s ushered in rampant drilling of private boreholes. This has culminated in the drying up of some shallow wells across the city, due to over-pumping.

Moses Souta, technician at the Department of Construction and Civil Engineering, University of Zimbabwe.

The failure of municipal infrastructure to meet the growing potable water demand has given rise to dependence on groundwater, with reports of 80 per cent of Harare population relying on groundwater supply (). 

During a trip to Harare in January 2023, BGS Bentje Brauns was able to visit a number of community drinking water sources.

You can see the impact of recent donor programmes to try and improve access to water in high-density settlements through developing groundwater resources. This has included upgrading boreholes and the installation of a large number of solar pumps, water tanks and in situ chlorination systems.

Bentje Brauns, BGS Hydrogeologist.

The challenge of finding drinking water

Though the city geology is variable, it is mostly ‘hard rock’ basement geology, therefore      groundwater occurrence is controlled by the presence of fractures. As a result, in some suburbs where there are few fractures, drilling may be unsuccessful or boreholes may only work for part of the year because of limited recharge through the fracture network. Poor sanitation and waste management as well as increasing urban pollution have compounded the challenge and have led to groundwater contamination. Some boreholes have been condemned as seasonal cholera and typhoid outbreaks affect communities.

Have recent donor upgrades to community supplies been effective?

A host of donors have worked in recent years to improve and upgrade groundwater drinking sources in high-density settlements across the city in response to this worsening water crisis. Recent communal borehole development projects include the establishment of community water point committees. These committees mobilise local resources, including household monetary contributions, to maintain the water point and continue with chlorination initiated by the donors when the borehole was completed. However, continued chlorination has been reported to be a challenge at many water points because the communities fail to raise the required funding, or the water point committees fail to thrive.

The question remains: have these upgraded sources been effective in providing improved drinking water quality and can they be sustainable, at least in the medium term?

Dan Lapworth, BGS Principal Hydrogeochemist.

We are trying to answer these questions through our collaboration to inform future policy on groundwater development in Harare and elsewhere in this region.

Samson Shumba, engineer and chairman of the Department of Construction and Civil Engineering, University of Zimbabwe.

Assessing groundwater quality in recently improved and historical sources

Monitoring groundwater resources and quality is critical to ensuring the sustainability and safety of water supplies. While big steps have been made recently in implementing monitoring systems, gaps in our understanding certainly remain and opportunities exist for closer monitoring of the water quality and quantity.

Funding

This work is being undertaken as part of the International Geoscience Research and Development (IGRD) project ‘Geoscience to tackle global environmental challenges’ (NERC reference NE/X006255/1). This is a £12 million project lasting until 2026, looking at challenges facing communities around the globe, including clean water availability, earth hazards and climate change impacts.

About the authors

, geoscientist at ZIVA Data & Knowledge Management Consultants

, consultant hydrogeologist at the Africa Groundwater Network

, engineer and chairman of the Department of Construction and Civil Engineering, University of Zimbabwe

, technician at the Department of Construction and Civil Engineering, University of Zimbabwe

Researchers from BGS and partners in Zimbabwe report on the urban water supply challenge in the capital city, Harare.