An invisible soil acidification: Critical role of soil carbonate and its impact on heavy metal bioavailability
Date
2015-07-31
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Nature Publishing Group
Abstract
It is well known that carbonates inhibit heavy metals transferring from soil to plants, yet the
mechanism is poorly understood. Based on the Yangtze River delta area, we investigated
bioaccumulation of Ni and Cd in winter wheat as affected by the presence of carbonates in soil.
This study aimed to determine the mechanism through which soil carbonates restrict transport
and plant uptake of heavy metals in the wheat cropping system. The results indicate that soil
carbonates critically influenced heavy metal transfer from soil to plants and presented a tipping
point. Wheat grains harvested from carbonates-depleted (due to severe leaching) soils showed Ni
and Cd concentrations 2–3 times higher than those of the wheat grains from carbonates-containing
soils. Correspondingly, the incidence of Ni or Cd contamination in the wheat grain samples increased
by about three times. With the carbonate concentration >1% in soil, uptake and bioaccumulation
of Ni and Cd by winter wheat was independent with the soil pH and carbonate content. The findings
suggest that soil carbonates play a critical role in heavy metal transfer from soil to plants, implying
that monitoring soil carbonate may be necessary in addition to soil pH for the evaluating soil quality
and food safety.
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Citation
Wang, C. et al. An invisible soil acidification: Critical role of soil carbonate and its impact on heavy metal bioavailability. Sci. Rep. 5, 12735; doi: 10.1038/srep12735 (2015).