The Innovation Platform spoke with the British Geological Survey about its collaborative study for the Environment Agency investigating PFAS concentrations in archive and new shallow soil samples
PFAS are now widely recognised as a pressing environmental concern. They are pervasive, accumulating across environments – including soils. A collaborative study between the British Geological Survey (BGS) and the Environment Agency shed light on this pressing issue, focusing specifically on PFAS concentrations in shallow soils across England. Detailed through a co-authored journal article, the study compared archive and contemporary PFAS concentrations in targeted soil samples to identify patterns and trends over time.
To learn more, we spoke with the British Geological Survey about the research, its findings, and how it improved our understanding of PFAS prevalence and its potential environmental consequences in shallow soils across England.
Can you outline the key findings discussed in the BGS co-authored journal article, “A Comparative Analysis of PFAS in Archive and Fresh Soil Samples in England”? How do the results of this study inform our understanding of historical versus contemporary levels of PFAS in English soils?
The study provides a published comparison of archived and contemporary shallow soils to assess whether historical samples could be used to determine background concentrations of PFAS in England.
The key findings were:
- PFAS were detected in both archived and paired contemporary soils, demonstrating that these compounds have been present in the English environment for many years.
- Contemporary soils generally contained higher concentrations and a greater diversity of PFAS compounds than historical archived soils.
- Although sample numbers were low, the widespread occurrence of PFAS at similar concentrations demonstrates that PFAS contamination is not likely to be confined to recognised point sources but rather diffuse background over the country. This assumption is comparable to background studies in other countries.
- Contemporary samples should form the principal sample type in any future national survey in England.
- PFAS are likely to have become a common component of the soil environment in England. The comparison between historical and contemporary samples provides some evidence that environmental burdens may have increased over recent years and that soil acts as a long-term reservoir for these persistent chemicals.
What are the challenges in addressing PFAS concentrations in soils?
There are several challenges. PFAS comprise thousands of individual chemicals with differing environmental behaviours, making comprehensive monitoring difficult.
PFAS are widespread and persistent. Unlike many other organic contaminants, they do not readily degrade, meaning conventional natural attenuation is expected to be very slow.
There remains limited understanding of:
- The factors affecting the fate and transport of PFAS in soil;
- How mixtures behave in different soil types;
- Long-term mobility and degradation; and
- Bioavailability of the chemicals in soil, plants, animals, and humans
- Long-term persistence and effects on human and environmental receptors
- Shallow soil sampling at a single depth (e.g., 5-20 cm)may not capture ‘peak’ concentrations and may underestimate PFAS concentrations in soil that are potentially available to plants/crops.
Analytical challenges exist, but laboratories continue to improve methods for detecting an increasing number of PFAS at lower concentrations. PFAS analysis is much more expensive than other common forms of contamination, which can constrain large-scale studies.
From a remediation perspective, removing PFAS from soil is technically difficult and expensive.
The regulatory frameworks for the UK continue to evolve as scientific understanding improves. The Government’s PFAS Plan and recent response begin to address some of these challenges.
What implications do the findings have for future environmental monitoring and regulatory practices regarding PFAS?
Our study highlights the challenges of establishing scientifically robust baseline datasets for PFAS in soils across England. BGS are well placed to deliver this work, as recognised in the Government’s PFAS plan
Key implications include:
- PFAS should be incorporated into routine national soil monitoring programmes;
- Archived environmental collections could have a role in evaluating long-term trends;
- Analytical methods could help to quantify the effect of replacement PFAS and other persistent organic pollutants;
- Improved understanding of diffuse PFAS pollution is an important factor in being able to differentiate between background and point sources, where the latter may require more focused regulatory interventions and/ or remediation;
- Background studies can support the development of risk-based soil assessment criteria for a range of land uses;
- Estimating PFAS bioavailability and its role in risk assessment and remediation is a gap that could be addressed by future studies; and
- Background studies can inform environmental policy and land management decisions.
The findings also demonstrate the value of long-term environmental archives and data hosted by BGS and others, which can help researchers to distinguish historical contamination from current environmental conditions.
As regulatory frameworks continue to develop in the UK and internationally, national-scale datasets such as these and BGS’ role in interpreting and applied knowledge will provide an important evidence base for policy development, environmental surveillance and prioritisation of future investigations.
Can you discuss any future studies that BGS might be considering to expand on the findings of this research?
While specific future projects will depend on research funding and partnerships with the Environment Agency and others, the study identifies several important areas for further investigation.
Potential future research directions include:
- Expanding the survey to provide greater spatial coverage across England and the wider UK;
- Investigating the environmental behaviour of newer short-chain and replacement PFAS compounds;
- Examining how soil properties influence PFAS retention and mobility;
- Assessing changes in PFAS concentrations within vertical soil profiles;
- Assessing movement from soils into groundwater, surface water and crops;
- Integrating PFAS measurements with national geochemical mapping programmes;
- Developing predictive models to identify areas where PFAS are more likely to accumulate;
- Improving understanding of temporal and spatial trends through additional analyses of archived and contemporary environmental samples;
- Measuring soil PFAS bioavailability in plants, animals, and humans; and
- Supporting the development of evidence-based environmental guidelines through collaboration with regulators and other research organisations.
More broadly, BGS contributes to PFAS challenges using expertise in national-scale geological and geochemical surveys, environmental monitoring, subsurface processes and modelling, environmental data integration, and its data and sample archives.
