Analysis of heavy metals in poplar leaves by femtosecond filament-induced breakdown spectroscopy

Femtosecond filament-induced breakdown spectroscopy (FIBS) is employed to qualitatively analyze the heavy metal elements (Ca, Fe and Cr) in poplar leaves, at the same age, from four representative locations in Changchun City, i.e. Changchun First Automobile Factory, Railway Station, Jingyue National Forest Park, and Changchun University of Science and Technology (CUST) in the same season. The stem and mesophyll from the same leaf are investigated as samples by the FIBS technique. Experimental results demonstrate that the concentration of Ca and Fe elements in the leaf stem are higher than those in the leaf mesophyll through comparing the spectral intensities of Ca II 393.37 nm and Fe I 422.87 nm. Based on the analysis of the FIBS spectral intensity of heavy metals mentioned above in the poplar leaves from the four different locations, the heavy metal elements Ca, Fe and Cr in the poplar leaves gathered from the Automobile factory area have the highest concentration among the four locations, and those from Jingyue National Forest Park are the lowest. The FIBS technique can obtain stable plasma spectrum for the poplar leaves with irregular surfaces because of the optical intensity clamping effect inside the femtosecond filament. This experiment demonstrates that FIBS can be utilized to find new applications in the environmental pollution on-site detection.