By Sabrina Cipullo, AMRSC
Marie Curie Early Stage Researcher in Environmental Technology
Sabrina Cipullo, AMRSC, Marie Curie Early Stage Researcher (ESR) in Environmental Technology, working on Environmental Chemistry and toxicological approaches to site assessments, explains how this 4 year EU project can provide better informed solutions for remediation.
Land is legally defined as ‘contaminated’ when substances (e.g heavy metals, oils, tars, and asbestos) may cause significant harm to people, property, protected species, or pollution of surface and ground water. An estimate of 250,000 sites in Europe solely are thought to be affected by contamination left by industrial activities, including leaks and spillages from pipes or tanks, mining, and waste disposal in landfill.
According to national estimates, more than 8% of the sites are contaminated and need remediation, and the overall number is estimated to grow by more than 50% by 2025. Most of the European countries apply the “polluter-pays” principle, when possible. However, large sums of public money are still required to fund remediation activities, where average unitary costs for the investigation of a potentially contaminated site can cost up to 50,000 EUR (42,000 GBP). Soil remediation technologies have developed significantly in the last 25 years, but less attention has been paid to improving the investigation strategies. Environmental site assessments still relies on intrusive grab sampling based on an outmoded geotechnical mind-set.
The REMEDIATE ITN
REMEDIATE ITN is a four-year project funded by the European Union’s Horizon 2020 Programme, which brings together internationally renowned research and industrial expertise to develop new strategies to improve management of contaminated sites. The project is tackling different aspects through 13 individual research projects, ranging from Environmental chemistry and toxicology, molecular microbiology, to geophysics and modelling. The researchers joined REMEDIATE from all over the world: China, Nepal, Canada, USA, India, Iran, Italy, Moldova, Serbia, and Portugal. The outcome of the research projects will feed into a cohesive and integrated approach that will deliver innovative technologies and commercial processes for contaminated site investigation, risk assessment and monitoring for effective remediation.
From a hazard-approach to a proportionate assessment of risk (risk-based-approach)
The level of implementation of pollution prevention measures, risk assessment, and management approaches are applied unevenly across Europe, depending on different legal requirements and national management strategies. At present, there are no common legal requirements concerning soil quality standards; however targets for the remediation of sites have been set by some European member countries. Great Britain has a comprehensive legal framework, including Part 2A of the Environmental Protection Act (EPA) 1990, which addresses identification of contaminated sites and removal or reduction of risk to receptors and environment. Overall, since the early 90s, there have been major changes in the field of contaminated land, moving from a hazard-approach to a proportionate assessment of risk (risk-based-approach) based on the source-pathway-receptor framework, now widely accepted by policy makers.
Risk-based approaches depend on the likelihood and severity of exposure of the receptor to the contaminants; therefore evaluating exposure routes (oral ingestion, inhalation or dermal exposure) is fundamental to correctly estimate potential intake dose. However, when a receptor is exposed to contaminated soil and ingestion occurs, the chemical released from the soil (available for uptake) will depend on how tightly the contaminant is bounded to soil particles. Soil Guideline Values (SGVs), largely used, simplified the initial screening process at contaminated sites. These measurements rely on total contaminants’ concentration, and are frequently considered primary basis for making soil clean-up decisions.
In nearly 10 years since the SGV were developed, more research has shown that pollutants in soil are subjected to ageing or disappearance due to leaching, volatilisation or microbial degradation. The decline in contaminants’ concentration, and consequently its bioavailable fraction, is not currently reflected in the chemical methods, hence exposure is often overestimated and clean-up requirements can be unnecessarily stringent.
Lately, governments want to avoid over-conservative measures and are encouraging standards to be relaxed. In an era of great demand for decision support tools, new reliable methodologies are required to assist sustainable land management development and help qualifying and quantifying risk posed by contaminants. This new area of risk assessment focuses on evaluating a range of in vitro tests for predicting the bioavailable and bioaccessible fraction and how to implement these data in the risk assessment. Queen’s University Belfast, Cranfield University, Dublin City University, University of Duisburg-Essen, University of Turin, TE Laboratories Limited, will collaborate in developing improved methodologies for investigation of complex environmental chemistry of contaminated land, improving our understanding of contaminant distribution, and toxicological impacts on potential receptors. In particular, Queens University of Belfast, in collaboration with the British Geological Survey are working on the BARGE (Bioaccessibility Research Group of Europe) Unified Bioaccessibility Method to assess human exposure from ingestion of soils (ISO/DIS 17924). This method simulates the human gastrointestinal tract using 4 synthetic digestive fluids: saliva, gastric fluid, duodenal fluid and bile, and provides estimates of the metal soluble fraction in the gastrointestinal environment, giving information on risk and potential human uptake. Dublin City University and University of Duisburg-Essen are studying organic compound (polycyclic aromatic hydrocarbons) degradation in soil and water, and developing advanced monitoring methods; part of this work has been already awarded a prize at the ISEH2016 international conference in Ireland.
Remediation success depends on microbial community structure and diversity
Understanding and improving the way we assess risk through Environmental chemistry and toxicology approaches to site assessments is only one of the multiple aspects that REMEDIATE wants to tackle. The co-occurrence of polycyclic aromatic hydrocarbons and heavy metals, commonly found in many industrialised and urbanised areas, can have a negative impact on soil microbial communities and their enzyme activities, inhibiting biodegradation and therefore hampering remediation success. Researchers at Queen’s University Belfast and University of Copenhagen are studying contamination impacts on microbial diversity through advanced metagenomics techniques and plant-microorganisms relationships to improve monitoring and remediation tools for metal polluted sites. Part of this research is carried out at Collstrup site in Hillerød, Denmark, where wood poles used to be impregnated with copper, chromium, and arsenic as a wood preservative, hence the main contamination on site has affected both top soil and shallow groundwater. The aim is to explore the relationship between the microbial activity, microbial biomass, and functional diversity of soil bacteria, and provide more information on the impact of mixed and long-term contamination.
Understanding the complexity of soil, chemical and microbial interaction is only part of a successful remediation strategy. In fact, successful monitoring of bio-product, toxins, and environmental pollutants, is an important task in the field of environmental science. In recent years, live cells have been employed as biosensors for a wide range of targets; Dublin City University and Queen’s University Belfast work on geophysical approaches to monitor remediation processes through microbial fuel cell biosensors applications. Biosensor combines biological molecules with a physical transducer able to provide quantitative analytical data that can be related to the target concentrations. The use of biosensors offer rapid and real time monitoring, and it is becoming an area of great interest due to its potential applications on site.
Impact and outreach
Achieving a sustainable use of land and water is a political and social objective of the community. The aim of REMEDIATE is developing research, exchanging knowledge and experience on technical concepts of contaminated land. Each researcher will be able to deliver quality research from the scientific and technical training at their host site; in addition they will work closely with industry, thanks to the secondment within the network. Private sector beneficiaries TEL, SUP and IWW, offer training programmes and opportunities to deliver real world solutions and support career enhancement. The ESRs already had multiple opportunities to interact and collaborate with the industrial sector, developing network and exporting their knowledge. I recently became a STEM ambassador to inspire and engage young people about science, technology, engineering and mathematics. Thus I have also been involved in outreach activities, for example Science Uncovered at the National History Museum (Part of European Researchers’ Night sponsored by HORIZON 2020) in order to help people better understand contaminated land and its impacts. Finally, thanks to Soapbox Science selecting me as a speaker, I will have the chance to take part in the Milton Keynes event on Saturday 29 July 12 – 3 pm. In addition, I also engaged with industry and have been invited to present my work at #YourSOILution conference on Tuesday 13th December, an event organised by ALS Environmental and present at the Contamination Expo Series in London.