Effects of Control Methods on Bioconcentration and Translocation of Cadmium between Soil and Rice Plants

  Objective   Effects of various pollution control methods on Cd accumulation and transport between contaminated soil and rice plants grown on the land were analyzed.

  Method   Field experiments were conducted on the contaminated lots at Liling and Yiyang of Hunan Province to investigate the effects of various control measures, including eliminating atmospheric Cd deposition, cleansing land by irrigation, and removing contaminated spent straws from field, as well as applying lime on soil, along with returning cut rice straws to land as control (CK).

  Result   Other than the lime application, the tested methods yielded no significant effects on Cd in soil in comparison to CK. Lime significantly neutralized Cd in soil and reduced the heavy metal content in rice grown on the lot. Compared with CK, the acid-extractable Cd in soil was lowest under the lime treatment and highest with straws removal, which also resulted in partial conversion of the reducible Cd to the acid-extractable fractions. The lime application, atmospheric pollution cutoff, or irrigation with groundwater could lower the Cd bioconcentration and accumulation in the aboveground rice tissues. For instance, a reduction on Cd in rice grains of approximately 40% by the lime application or 8% by the atmospheric interception was achieved.

  Conclusion  The treatments on Cd contaminated soil by lime application, deposition prevention, water cleansing, or straw removal could reduce in varying degrees of heavy metal accumulation in rice improving safety of the food consumption.