Abstract
Rapid heavy metal soil surveys at large scale with high sampling density could not be conducted with traditional laboratory physical and chemical analyses because of the high cost, low efficiency and heavy workload involved. This study explored a rapid approach to assess heavy metals contamination in 301 farmland soils from Fuyang in Zhejiang Province, in the southern Yangtze River Delta, China, using portable proximal soil sensors. Portable X-ray fluorescence spectroscopy (PXRF) was used to determine soil heavy metals total concentrations while soil pH was predicted by portable visible-near infrared spectroscopy (PVNIR). Zn, Cu and Pb were successfully predicted by PXRF (R2 >0.90 and RPD >2.50) while As and Ni were predicted with less accuracy (R2 <0.75 and RPD <1.40). The pH values were well predicted by PVNIR. Classification of heavy metals contamination grades in farmland soils was conducted based on previous results; the Kappa coefficient was 0.87, which showed that the combination of PXRF and PVNIR was an effective and rapid method to determine the degree of pollution with soil heavy metals. This study provides a new approach to assess soil heavy metals pollution; this method will facilitate large-scale surveys of soil heavy metal pollution.
Highlights
Soil contamination with heavy metals has become a worldwide environmental issue [1,2,3,4] and there are serious problems with soil heavy metals pollution in China
For Cd and Hg, limits of detection (LOD) were much higher than the guideline threshold concentrations in arable land defined in the Environmental Quality Standard for Soils (EQSS), and the LOD of Cr was quite close to the guideline threshold concentration, so in this study we focused on the other five heavy metals, including Pb, As, Cu, Zn and Ni [24]
This study provides a method to verify the soil heavy metal pollution grades classification synthesizing Portable X-ray fluorescence spectroscopy (PXRF) and portable visible-near infrared spectroscopy (PVNIR)
Summary
Soil contamination with heavy metals has become a worldwide environmental issue [1,2,3,4] and there are serious problems with soil heavy metals pollution in China. According to The National Soil Pollution Condition Investigation Communique released by the Ministry of Environmental Protection and Ministry of Land and Resources on April 17th, 2014, the proportion of contaminated samples in China is 16.1% [5]. There is an urgent need to complete high-density soil sampling to determine the boundaries of contaminated areas and to prevent and control further soil pollution. Traditional laboratory analyses of heavy metals in soils, such as AFS (Atomic Fluorescence Spectrometry), AAS (Atomic Absorption Spectrometry) and ICP-OES (Inductively Coupled Plasma Optical Emission Spectroscopy), are time-.
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