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. 2015 Jan 28;12(2):1577-94.
doi: 10.3390/ijerph120201577.

Contamination and spatial variation of heavy metals in the soil-rice system in Nanxun County, Southeastern China

Keli Zhao  1 , Weijun Fu  2 , Zhengqian Ye  3 , Chaosheng Zhang  4
Affiliations

Contamination and spatial variation of heavy metals in the soil-rice system in Nanxun County, Southeastern China

Keli Zhao et al. Int J Environ Res Public Health. .

Abstract

There is an increasing concern about heavy metal contamination in farmland in China and worldwide. In order to reveal the spatial features of heavy metals in the soil-rice system, soil and rice samples were collected from Nanxun, Southeastern China. Compared with the guideline values, elevated concentrations of heavy metals in soils were observed, while heavy metals in rice still remained at a safe level. Heavy metals in soils and rice had moderate to strong spatial dependence (nugget/sill ratios: 13.2% to 49.9%). The spatial distribution of copper (Cu), nickel (Ni), lead (Pb) and zinc (Zn) in soils illustrated that their high concentrations were located in the southeast part. The high concentrations of cadmium (Cd) in soils were observed in the northeast part. The accumulation of all the studied metals is related to the long-term application of agrochemicals and industrial activities. Heavy metals in rice showed different spatial distribution patterns. Cross-correlograms were produced to quantitatively determine the spatial correlation between soil properties and heavy metals composition in rice. The pH and soil organic matter had significant spatial correlations with the concentration of heavy metals in rice. Most of the selected variables had clear spatial correlation ranges for heavy metals in rice, which could be further applied to divide agricultural management zones.

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Figures

Figure 1
Figure 1
Location of the study area and sample sites.
Figure 2
Figure 2
Enrichment index of heavy metal concentrations between soil and rice in paddy field. Different capital letters mean significantly different at the 0.05 level.
Figure 3
Figure 3
Spatial distribution maps of heavy metals in soils.
Figure 4
Figure 4
Spatial distribution maps of heavy metals in rice.
Figure 5
Figure 5
The estimated probability map of Cd and Ni.
Figure 6
Figure 6
Cross-correlograms for each heavy metal between heavy metal in rice and soil properties, total heavy metal in soil. (** Correlation is significant at the 0.01 level; * correlation is significant at the 0.05 level).
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