Field assessment of Pb in contaminated soils and in leaf mustard (Brassica juncea): the LIBS technique

Monitoring contaminated sites is faster and cheaper if portable analytical instruments are used rather than traditional laboratory analysis. We developed a transportable system based on the laser-induced breakdown spectroscopy (LIBS) technique for rapid on-site measurement of heavy metal concentrations. Portable instruments also offer great advantages for on-site remediation technology, where continuous monitoring is required. LIBS is especially useful when plants are used to remove or contain contaminants. Phytoremediation takes time to achieve its goals, and many analyses are required to evaluate its efficiency during the process. In this study, LIBS was used to measure Pb concentration in soils from three contaminated sites and in plant samples from phytoremediation experiments. Results obtained from LIBS show good correlation with data obtained with atomic absorption spectroscopy (AAS). In particular, in the case of contaminated site characterisation, LIBS permits delimitation of areas showing metal concentration over the legal limits, where further investigations are required. Speeding up the characterisation procedure decreases investigation costs and increases the number of analysed samples with a given economic budget, thus increasing the informational value of data. Thus reliable spatial information can be obtained, leading to lower remediation costs.