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Environmental fate & pathways

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The percent distribution data generated using the Fugacity level III model of EPIWEB 4.1 indicates that C12-16 ADBAC is likely to partition mostly to the soil (47.38%) and sediment (47.12%) compartments and to a lesser extent to water (5.42%) and air (0.03%) (U.S. EPA, 2012b). However, considering its ready biodegradability, toxicokinetics data as well as the low BCF value (66.74 L/kg ww), C12-16 ADBAC is not expected to be persistent in the environment. The low vapour pressure (< 5.8 x10- 3Pa at 25°C) together with low Henry’s coefficient of <1.1 x 10-11Pa-m3/mole and the percent distribution data from the Level III fugacity modelling confirm that C12-16 ADBAC has a low potential to distribute into the atmospheric compartment.

The experimentally determined Koc values of 282,624 and 2,658,608 (log Koc: 5.5 to 6.4) indicate that C12-16 ADBACwill adsorb onto soil, does not desorb easily and can considered immobile. Cationic surfactants adsorb to soil mainly due to ionic interaction with negatively charged surfaces. This means that there will be a poor correlation with organic carbon in soil. This means that sorption should not be normalized to the organic matter content in soil but instead it is better to use the average Kd values to estimate solids-water partition coefficient in soil. When organic matter is not determining the distribution in soil, sediment and suspended sediment, there is no difference in adsorption to these three compartments (based on dry weight) as the organic matter content is the only variable. This means that also the solids-water partition coefficients in sediment and suspended sediment are both equal to 13,630 L/kg.