Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

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Additional information

Due to the inorganic nature of these compounds biodegradation is not considered relevant. ‘Water soluble’ barium compounds such as barium chloride and barium nitrate release barium ions in the aquatic compartment. These barium ions then undergo speciation in the aquatic compartment. Barium cations can form soluble complexes with several ligands, but complexation with specific ligands results in massive precipitation of barium from solution (e.g., as barium sulfate, barium carbonate). Increasing pH typically reduces the amount of free bioavailable metal cation in solution. The amount of free bioavailable metal cation in solution will determine toxicity to aquatic organisms. Other processes that may lead to removal of barium from solution are adsorption and bioaccumulation. Adsorption of barium to particulate organic matter is similar to that of many other metals. In soil, adsorption seems to be weaker than in sediment or suspended matter. Further, bioaccumulation is most likely not a very important process as the available data indicate that barium has a limited capacity for bioaccumulation throughout the foodchain. Finally, in sediment and soil, bioavailability of barium is also expected to be quite low due to formation of insoluble complexes.