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Environmental fate & pathways

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In water (including soil or sediment pore water) sodium methanolate dissociates quickly into methanol and sodium hydroxide. For the hydroxides it was concluded that they will be found predominantly in the aquatic compartment as alkali metal and hydroxide ions and will not adsorb on particulate matter or surfaces (OECD SIDS sodium hydroxide, 2002). For methanol, measured and calculated Koc values < 1 (Lokke 1984, study director 2003, BASF 2004) demonstrate the low soil adsorption potential.

The Henry's Law constant for sodium methanolate was calculated via QSAR and resulted in a value of 0.304 Pa m3/mol (study director 2005) (based on methanol as surrogate).
Similary, Gaffney et al. (1987) published a Henry’s law constant of 0.461 Pa m³/mol for methanol. Hence, sodium methanolate and its degradation product methanol are not expected to significantly volatilise from surface water and volatilisation is not a significant removal process from the aquatic compartment. Sodium hydroxide dissociates in water and is also expected to remain in the aquatic compartment

The distribution of sodium methanolate was calculated with the Mackay Level I as well as with the more complex Level III model (methanol was used as surrogate). Based on the Mackay Level I fugacity model the majority of methanol is calculated to partition into the water phase (BASF, 2009). In addition a distribution calculation with the Mackay Level III fugacity model (BASF, 2003) was performed. This is a comprehensive multimedia model in which chemical emission, advection, reaction, intermedia transport and residence time or persistence are taken into account and therefore the model provides a more realistic representation of the fate of methanol in the environment. Using emission rates derived from total releases into water, air and soil (79658, 1531 and 658 tonnes, respectively) reported in the U.S. Toxics Release Inventory for 2001 the model predicts that the air is the target environmental compartment for methanol.