Abstract
Pollution from potentially toxic trace elements (PTEs) is becoming serious and widespread in farmland soils in China, threatening food security and human health. Few large-scale studies systematically analyzed their temporal-spatial trends over vast spatially elaborate sites. The soil health status of the main grain producing areas was first announced based on a total of 3662 spatially elaborate farmland topsoil sites from the 1980s to the 2000s. Nearly 21.5% of sites were polluted, although only slightly. Pollution from the Cd, Ni, Cu, Zn, and Hg was more serious. Pollution was more extensive in the south than in the north. There was an increasing trend in the PTE concentrations, especially Cd with a growth of 21–25%, and in the proportion of mixed pollution at the sites (19.3%), Cd (21.5%), Pb (3.6%), Zn (5.7%), Cu (7.0%), and Hg (3.1%). Furthermore, temporal variations in severe Cd pollution and mixed-level Hg pollution in the north are severer. This study may provide guidance for policymakers regarding the protection and high-risk area of PTE contamination in the soils.
Highlights
“Potentially toxic trace elements (PTEs)”, which are more inclusive and appropriate than the term “heavy metals1” in soils, are an issue of increasingly serious concern because of their persistence and biotoxicity[2,3,4]
The median concentrations of Cd (0.159 versus BV limit of 0.097), Ni (27.76 versus BV limit of 26.9), Cu (23.94 versus BV limit of 22.6), and Cr (62.30 versus BV limit of 61) are higher than the background values in China (Table 1). This suggests that in at least half of the farmland soil samples, these four potentially toxic trace elements (PTEs) come from anthropogenic sources as well as from the parent rock
This study found that 21.5% of the agricultural soils in the FMGPRs were excessively polluted; this figure is slightly higher than the results of nationwide surveys conducted in 2014, which found that 19.4% of agricultural soils were contaminated with PTEs35,60
Summary
“Potentially toxic trace elements (PTEs)”, which are more inclusive and appropriate than the term “heavy metals1” in soils, are an issue of increasingly serious concern because of their persistence and biotoxicity[2,3,4]. Some studies focused on other land use types[35,36,37] These were insufficient to reveal the overall status of PTE pollution in the agricultural regions of China, where the soil is spatially elaborate soil, without some uncertainties. It is necessary to assess the temporal trends of PTEs in the agricultural soils of the FMGPRs. The main objectives of this study were to 1) determine the current status of PTEs in vast, spatially elaborate farmland topsoil over a large scale in the FMGPRs using the single factor index and revised comprehensive pollution index methods, 2) assess their temporal trends, from the 1980s to the 2000s, at the site- and grid-scale, and 3) to provide guidance for the policymakers regarding environmental management and the reduction and restriction of areas of high-risk soils for future food security and human health
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