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Environmental fate & pathways

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Additional information

Experimental data on the adsorption/desorption of dicalcium pyrophosphate are not available. Testing the adsorption/desorption behaviour according to OECD Guideline 121 is not feasible as the test method is not validated for inorganic substances. A batch equilibrium study according to OECD Guideline 106 was not conducted since an analysis of the test material may not be possible due to interference from the soil extracts that contain high levels of calcium and phosphate leaching into the aqueous media during the test. The soluble calcium and phosphate species are generally highly mobile and are present as ionic calcium and phosphate species in solution. The most common Ca-bearing minerals in sedimentary rocks, calcite and dolomite, weather on contact with acid solutions, typically carbonic acid (H2CO) derived from the dissolution of atmospheric CO2 in rain, releasing Ca2+. The CO concentrations in soil air are higher than those in the atmosphere, due to the respiration of soil organisms and the decay of organic matter. Soil solutions thus contain higher levels of HCO than rain, and have a greater capacity to dissolve carbonate minerals. Except in very acid or alkali conditions, phosphate exists mainly as organic or inorganic complexes which determine the transport and distribution behaviour of phosphorous (De Vos, 2006).

References

De Vos W. and Tarvainen T. (2006), Eds., Geochemical Atlas of Europe Part 2: Interpretation of Geochemical Mops, Additional Tables, Figures, Maps and Related Publications, EuroGeosurveys & Foregs, Espoo, Finland, 2006.