Registration Dossier

Administrative data

Link to relevant study record(s)

Description of key information

No data available

Key value for chemical safety assessment

Additional information

Potassium phosphonate is an inorganic salt, completely dissociated in water

Potassium is a natural component of water, sediment and soil and The K content of argillaceous sediments and shale is primarily a function of the clay mineral content, commonly illite in shale units. No concern about potassium ion is raised for sediments.

Potassium uptake by Hydrilla verticillata (L.f.) Royle from sediment versus overlying water was evaluated in relation to the K demands incurred by this species during an 8-week period of growth. The investigation was conducted on a heterogeneous assemblage of sediments and in two solutions differing fundamentally in the presence (2.3 mg lāˆ’1) and absence of K (Barko, 1982).

Both biomass production and shoot morphology in Hydrilla varied significantly between solutions and among sediments. In contrast to N and P, which were readily mobilized from most sediments, K was mobilized from all sediments to only a minor extent by this species. Mobilization of K was proportional to interstitial water K concentration; yet on at least four of the six sediments examined, K supplied from sediments was insufficient to support the maximal growth of Hydrilla. The open water rather than the sediment appears to be the primary source of K supply to this species and perhaps to most other submersed freshwater macrophytes (Barko, 1982).

 

No further information is available on the behaviour of phosphonate in sediments, even it can be assumed that it will enter in the cycle of phosphorous, being slowly oxidized to phosphate. No concern based on all results of toxicity on microorganisms, macroorganisms at several trophic levels is raised for sediments as a consequence. The environmental exposure assessment will be performed with the equilibrium partitioning method.

Barko John W.,Influence of potassium source (sediment vs. open water) and sediment composition on the growth and nutrition of a submersed freshwater macrophyte (Hydrilla verticillata) (L.f.) Royle),Aquatic Botany, Volume 12, 1982, Pages 157ā€“172