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Environmental fate & pathways

Adsorption / desorption

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Description of key information

Adsorption to solid soil phase is possible.

Key value for chemical safety assessment

Additional information

Due to the ionic nature of the substance the calculation of sorption onto organic soil matter does not have any practical meaning.

"Ammonia is bound in soil by the attraction of the positive charge on the ammonium ion to the negatively charged soil micelles. In soil, ammonium is adsorbed primarily by four mechanisms: chemical (exchangeable), fixation (non-exchangeable), reaction with organic matter and physical attractive forces."

 

"Since ammonia is so poorly mobile in soil, it is unlikely to leach to groundwater except under unusual circumstances, such as when the cation exchange capacity of the soil is exceeded. The worst situation for ammonium leaching would probably occur when the soil is at field capacity with respect to water."

References:

Environment Canada (2001). Priority substances list assessment report. Ammonia in the environment. http://www.hc-sc.gc.ca/ewh-semt/pubs/contaminants/psl2-lsp2/ammonia/ammonia_2-eng.php