title: Predicting molybdenum toxicity to higher plants: influence of soil properties.
abstract: The effect of soil properties on the toxicity of molybdenum (Mo) to four plant species was investigated. Soil organic carbon or ammonium-oxalate extractable Fe oxides were found to be the best predictors of the 50% effective dose (ED50) of Mo in different soils, explaining>65% of the variance in ED50 for four species except for ryegrass (26-38%). Molybdenum concentrations in soil solution and consequently plant uptake were increased when soil pH was artificially raised because sorption of Mo to amorphous oxides is greatly reduced at high pH. The addition of sulphate significantly decreased Mo uptake by oilseed rape. For risk assessment, we suggest that Mo toxicity values for plants should be normalised using soil amorphous iron oxide concentrations.
authors.affiliation: Soil Science Department, Centre for Soils and Ecosystems Functions, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK. steve.mcgrath@bbsrc.ac.uk
authors.forename: S P
authors.initials: SP
authors.lastname: McGrath
authors.forename: C
authors.initials: C
authors.lastname: Micó
authors.forename: R
authors.initials: R
authors.lastname: Curdy
authors.forename: F J
authors.initials: FJ
authors.lastname: Zhao
mesh_terms: D004305:Dose-Response Relationship, Drug; D005544:Forecasting; D006863:Hydrogen-Ion Concentration; D008982:Molybdenum / Q000633:toxicity*; D010944:Plants / Q000187:drug effects*; D018570:Risk Assessment; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000633:toxicity*; D013431:Sulfates / Q000737:chemistry
chemical_list: D012987:Soil; D012989:Soil Pollutants; D013431:Sulfates; D008982:Molybdenum