Cadmium availability to wheat grain in soils treated with sewage sludge or metal salts

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• 作者：Amar Chaudri ; Steve McGrath ; Paul Gibbs ; Brian Chambers ; Colin Carlton-Smith ; Andrew Godley ; Jeffrey Bacon ; Colin Campbell ; Mark Aitken
• 关键词：Field experiments ; Grain Cd ; Soil Cd ; Soil pH ; Soil organic carbon ; Limits
• 刊名：Chemosphere
• 出版年：2007
• 期刊代码：15_00456535
• 类别：env
• 出版时间：January 2007
• 卷：66
• 期：8
• 页码：1415-1423
• 文件大小：329 K

摘要

Grain Cd concentrations were determined in wheat (Triticum aestivum L.) grown in 1999, 2001 and 2003, at six sludge cake field experiments. Three of these sites also had comparisons with Cd availability from metal amended liquid sludge and metal salts. Grain Cd concentrations in all years and at all sites were significantly linearly correlated with NH₄NO₃ extractable Cd and soil total Cd (P < 0.001). Soil extractability was greater in the liquid sludge and metal salt experiments than in the cake experiments, as were grain Cd concentrations. Across all the sites, NH₄NO₃ extractable soil Cd was no better at predicting grain Cd than soil total Cd. Stepwise multiple linear regression analysis showed that soil total Cd, pH and organic carbon were the only significant (P < 0.001) variables influencing wheat grain Cd concentrations, explaining 78%of the variance across all field experiments (1408 plots). This regression predicted that the current UK soil total Cd limit of 3 mg kg⁻¹ was not sufficiently protective against producing grain above the European Union (EU) grain Cd Maximum Permissible Concentration (MPC) of 0.235 mg Cd kg⁻¹ dry weight, unless the soil pH was >6.8. Our predictions show that grain would be below the MPC with >95%confidence with the proposed new EU draft regulations permitting maximum total Cd concentrations in soils receiving sludge of 0.5 mg kg⁻¹ for soils of pH 5–6, 1 mg kg⁻¹ for soils of pH 6–7, and 1.5 mg kg⁻¹ for soils of pH 7.