Determination of Hg, As, Pb, and Cd in Orchard Soils by Sequential Injection Vapor Generation Atomic Fluorescence Spectrometry

Abstract

An analytical procedure was developed for determination of Hg, As, Pb, and Cd in soil samples using sequential injection vapor generation atomic fluorescence spectrometry (SI-VG-AFS) with sample preparation by microwave digestion system. The effects of analytical conditions on the fluorescence intensity were investigated and optimized. Under the optimized condition, the detection limits of the method were 5, 68, 40, and 3 ng L⁻¹ for Hg, As, Pb, and Cd, respectively. The accuracy of method was verified by the determination of the certified reference soil, and the recoveries for Hg, As, Pb, and Cd were in the range of 98.7–106.1%. The proposed method has been successfully applied to determine the heavy metals in navel orange orchard soils in Ganzhou, and the environmental quality of the orchard soils was assessed based on the content of the heavy metals. According to the second criterion of environmental quality standard for soils, Pb content in all soil samples collected from the orchards of 18 districts were within safe limits, but a few orchards were slightly contaminated with Hg, As, and Cd. Comparison of heavy metal mean concentrations with the safe limits of environmental quality standard for soils, the quality of Ganzhou navel orange orchard soils were in line with the request of the green food production base.

Keywords:

• Atomic fluorescence spectrometry
• Heavy metal
• Microwave digestion
• Orchard soil
• Sequential injection

Acknowledgments

The project was supported by the National Nature Science Foundation of China (No. 50968002). The authors gratefully acknowledge the Beijing Titan Instruments Co. Ltd. for helpful discussion on the SI system and AFS instrument.

Notes

^a The pH value of the orchard soils in Ganzhou are less than 6.5.