On-Site Contaminants Screening - Managing the Process

The construction industry is booming, with countries like the UK, China and the Philippines seeing substantial amounts of growth in this sector. As the industry grows, so does the need for organizations to consider how they manage the screening of on-site contaminants on construction sites.

Heavy elements are commonly used in a number of domestic, agricultural and industrial applications. This can result in their accumulation in specific geographic areas, for example old industrial or mining sites.

As heavy elements can have a harmful effect on human health, different departments for public and environmental health across the world have introduced soil screening programmes to help reduce contamination and prevent exposure to potentially harmful materials.

For example, the Environmental Protection Agency (EPA) in the United States has developed Soil Screening Guidance (SCG) to provide a framework for the development of screening levels and site evaluation protocols.

XRF Analyzer

Handheld XRF analyzers can screen soil for contaminants on site, therefore minimizing the number of samples sent to off-site laboratories and allowing quick identification of areas that need clean-up operations putting in place. It does this using semi-quantitative and qualitative data which can assist decision-making around further sampling strategies for the complete assessment of soil quality. The analyzer can also help with the monitoring of remediation work where this is required.

Product Manager Christelle Petiot outlines the advantages and limitations of handheld XRF (HHXRF) analyzer technology as well as sharing tips for obtaining the best results with these devices:

Why Invest in the Latest Handheld XRF Analyzers?

  1. Handheld devices are simply ‘point and shoot’ systems that require only the most minimal sample preparation. There are no reagents or chemicals required and the system will work even while wearing gloves or other protective clothing.
  2. These devices are totally portable and usable in harsh weather conditions. For example, certain HHXRF models such as the X-MET8000 are IP64 rated (splash water and dust proof) and tested to MIL-STD-810G military standard for robustness.
  3. Handheld XRF devices are quick to use. New developments in detector electronics have drastically minimized the time required to test samples. It is possible for users to increase the test density for more detailed analysis and better-informed decision making. This can also save time as users will be able to complete screening surveys on-site faster, and there is no need to wait potentially weeks for lab results.

Points to Consider

  1. What range of elements do users want to measure? A handheld analyzer is not sensitive enough for very light elements such as Be and Li. Typical elements range from Mg to U, based on the application.
  2. How detailed are the results that users need? The detection limits are higher than techniques like ICP-OES, ICP-MS or flame-AAS, and therefore HHXRF cannot fully replace laboratory analysis.

Tips for Getting Good Results

In order to guarantee better results from soil analysis, additional steps can be taken to pre-treat soil samples. For example:

Rocks and debris should be removed, and the area flattened with a non-metallic object to smooth out the surface. This should be done prior to testing. Soil can be sieved or ground to acquire a fine particle size, and this powder can be placed in a thin sample bag or cup for analysis.

Samples must be as dry as possible. The sample can be left to air-dry in a well-ventilated area if needed, or absorbent paper can be used to remove moisture directly. Moisture levels over 10 % can have an adverse effect on the accuracy of results, and these are usually 70 – 80 % of the laboratory reported values where the sample contains 15 to 25 % water.

Regularly measure a blank sample (for example SiO2 in a cup) to test for contamination and change the analysis window when required.

It is also advisable to measure a known soil check sample regularly. This allows the user to verify stability and accuracy.

This information has been sourced, reviewed and adapted from materials provided by Hitachi High-Tech Analytical Science.

For more information on this source, please visit Hitachi High-Tech Analytical Science.

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