In soil Molybdenum

Schalscha EB, Morales M, Pratt P. 1987. Lead and molybdenum in soils and forage near an atmospheric source. Journal of Environ Quality 16 313-315. 

The application of inductively coupled plasma atomic emission spectrometry and graphite furnace atomic absorption spectrometry to the determination of cadmium (and molybdenum) in soils has been discussed by Baucells et al. [53]. Baucells et al. chose the 228.802 nm cadmium line because it is well resolved from the 228.763 nm iron line with the spectrometer used in this work. Background measurements could only be carried out at +0.05 nm. These workers obtained good agreement between cadmium values obtained by direct graphite furnace atomic absorption spectrometry and inductively coupled plasma atomic emission spectrometry. Chelation extraction procedures that require extensive sample handling are avoided. 

Official methods have been published for the determination of extract-able [162] and total [163] molybdenum in soil. 

Earlier atomic absorption methods [164-167] from the determination of molybdenum in soils employed a preliminary solvent extraction step to improve sensitivity in view of the low concentrations of molybdenum occurring in most soils. Baucells et al. [5] developed a graphite furnace atomic absorption procedure which was capable of determining down to 8.4 pg of molybdenum in a soil matrix solution with a precision of 4% for 100 pg/1 molybdenum. These workers showed that a char temperature of 1500 °C and an atomisation tem-... 

Thompson and Zao [170] have described a solvent extraction-inductively coupled plasma atomic emission spectrometric method for the determination of down to 0.02 - 0.03 xg/g of molybdenum in soils. The soil sample is pressure-leached with 6 M hydrochloric acid and at 120 °C for 15 minutes. The digest is then extracted with heptan-2-one to separate molybdenum from potentially interfering elements such as iron, aluminium, calcium and magnesium. This organic extract is then directly sprayed into an inductively coupled plasma atomic emission spectrometer operated at 1.65 to 1.7 kW power. 

The determination of molybdenum in soil is of interest because molybdenum is necessary for normal crop growth, but an excess in forage has a toxic effect on ruminants. The absorption of molybdenum by plants is influenced by other soil components, especially extractable iron, pH and organic matter. The average abundance of molybdenum in soils is about 2 ppm, but deficient soils can have much less than 1 ppm [171]. Jiao et al. [172] and Rowbottom [173] have reviewed methods for the determination of molybdenum in soils. 

Zhlng L and Qi-qing (1989) Status of molybdenum in soils of China. In Anke M etal., eds. 6 th International Trace Element Symposium. Molybdenum, Vanadium, Vol. 1, pp. 185-191. University Leipzig and Jena, Germany. 

Chemical Processes Controlling Dissolved Molybdenum in Soils Speciation of Dissolved Molybdenum... 

Chemistry and Mineralogy of Molybdenum in Soils Table 2.1. Speciation of dissolved Mo in soil solutions... 

Barber, S. A. (1984). Molybdenum. In Soil Nutrient Bioavailability, pp. 338-45. New York Wiley. 

Rowbottom, W. H. (1991). Determination of ammonium acetate extractable molybdenum in soil, and aqua regia (hydrochloric acid and nitric acid,... 

Stanton, R. E., and Hardwick, A. J. (1967). The colorimetric determination of molybdenum in soils and sediments by zinc dithiol. Analyst 92 387-90. 

Analytical Procedures for Plant-available Molybdenum in Soils... 

Gupta, U. C., and Cutcliffe, J. A. (1968). Influence of phosphorus on molybdenum content of Brussels sprouts under field and greenhouse conditions and on recovery of added molybdenum in soil. Can. J. Soil Sci. 48 117-23. 

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