Evaluation of in Situ DGT Measurements for Predicting the Concentration of Cd in Chinese Field-Cultivated Rice: Impact of Soil Cd:Zn Ratios

Paul N. Williams*, Hao Zhang, William Davison, Shizhen Zhao, Ying Lu, Fei Dong, Lin Zhang, Qi Pan

*Corresponding author for this work

Research output: Contribution to journalArticle

39 Citations (Scopus)

Abstract

DGT (diffusive gradients in thin-films) has been proposed as a tool for predicting Cd concentrations in rice grain, but there is a lack of authenticating data. To further explore the relationship between DGT measured Cd and concentrations in rice cultivated in challenging, metal degraded, field locations with different heavy metal pollutant sources, 77 paired soil and grain samples were collected in Southern China from industrial zones, a "cancer village" impacted by mining waste and an organic farm. In situ deployments of DGT in flooded paddy rice rhizospheres were compared with a laboratory DGT assay on dried and rewetted soil. Total soil concentrations were a very poor predictor of plant uptake. Laboratory and field deployed DGT assays and porewater measurements were linearly related to grain concentrations in all but the most contaminated samples where plant toxicity occurred. The laboratory DGT assay was the best predictor of grain Cd concentrations, accommodating differences in soil Cd, pollutant source, and Cd:Zn ratios. Field DGT measurements showed that Zn availability in the flooded rice rhizospheres was greatly diminished compared to that of Cd, resulting in very high Cd:Zn ratios (0.1) compared to commonly observed values (0.005). These results demonstrate the potential of the DGT technique to predict Cd concentrations in field cultivated rice and demonstrate its robustness in a range of environments. Although, field deployments provided important details about in situ element stoichiometry, due to the inherent heterogeneity of the rice rhizosphere soils, deployment of DGT in dried and homogenized soils offers the best possibility of a soil screening tool.

Original languageEnglish
Pages (from-to)8009-8016
Number of pages8
JournalEnvironmental science & technology
Volume46
Issue number15
DOIs
Publication statusPublished - 07 Aug 2012

Keywords

  • BIOAVAILABILITY
  • CADMIUM UPTAKE
  • RISK-ASSESSMENT
  • PADDY SOILS
  • THIN-FILMS
  • COPPER AVAILABILITY
  • DIFFUSIVE GRADIENTS
  • METALS
  • SPECIATION
  • PLANTS

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry

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