Heavy metals contamination arising from previous industrial uses can be present in concentrations that may be hazardous to human health and the environment. It is therefore vital that an accurate assessment of the extent and spread of contamination is performed prior to redeveloping a site for a different end use.

Ecologia continually researches new technologies which can be combined with traditional investigative approaches to get faster, accurate results at minimal cost. The Energy Dispersive X-Ray Fluorescence (ED-XRF) analyser is a tool, which provides a means of testing quickly a wide range of heavy metals contamination both in the field and laboratory.

Why ED-XRF?

The XRF analyser generates X-rays which are fired at a sample. Elements in the sample fluoresce, giving off secondary X-rays. Each element gives off a unique range of secondary X-rays or ‘fingerprints’, which the XRF can compare to an on-board database while the instrument CPU compensates for potential distortion across a range of variables to ensure data accuracy.

This is a convenient technology to rapidly screen all kinds of materials for quick identification and allows quantification of elements with little or no sample preparation.

Handheld ED-XRF analysers enable accurate on-the-spot detection in just a few seconds, returning and with quite simple sample preparation, can return lab-grade results for immediate interpretation.

Analysing heavy metal concentrations in soil and assessing surface contamination

Ecologia have successfully used this tool to assist in the assessment of lead surface contamination at former shooting grounds earmarked for redevelopment.

Used for over 50 years as a clay pigeon shooting range, the area comprising open fields and woodland is affected by visible lead contamination at the surface, resulting from the accumulation of lead pellets over time. An assessment of the area was commissioned to determine the extent of the contamination and identify a sustainable remediation strategy.

The site was divided up into a grid system with soil samples collected at different depths to assess the surficial and vertical extent of the contamination. Locations were cross-referenced against a base map using GPS to record specific locations should further testing be required. Standard heavy metals laboratory chemical analysis was combined with the use of ED-XRF measurement in assessing the several soil samples collected across the site.

Fast and cost effective

Prior to using ED-XRF analysis, tests were performed to establish the differences between laboratory data (MCERTS certified) and ED-XRF analysis as soil moisture was known to cause some interference in the measurement. This was resolved by developing a sample preparation method prior to analysis, and with this Ecologia were able to prove a very high degree of correlation between the ED-XRF measurements and those from the MCERTS accredited lab. The opportunity to replace standard heavy metal analysis with ED-XRF measurement meant the study could be carried out less expensively in less time.

Heavy metals contamination in soil can be very heterogenous (i.e. samples taken close together can show big difference in concertation), so by being able to sample more discrete areas, Ecologia were able to have confidence in which areas were free of contamination, and which areas would require remediation. While the above  graph shows the high degree of correlation between regulatory-accepted MCERTS results and the ED-XRF for lead proving that this fast technique is very robust.

Initial findings have established that the heavy  metals contamination is confined to a relatively shallow depth, but present in solid state (as lead pellets) and also dissolved in soil as result of pellet’s degradation. Currently Ecologia is conducting lab feasibility testing to assess the potential economic benefits of recovering lead pellets and stabilising dissolved lead in the soil to allow for on-site reuse.

Do you have issues associated with extensive heavy metal pollution in relation to site assessment or verification of a remediation works which require a quick assessment?

Ecologia’s in house ED-XRF capability can offer a cost-effective solution. If you have a current project requirement or need advice, talk to our technical experts.