Reaction mass of ammonium sulphate and potassium sulfate and sodium sulphate

Toxicity to aquatic algae and cyanobacteria

Description of key information

With high probability not acutely harmful to algae.

Key value for chemical safety assessment

EC50 for freshwater algae:

2 700 mg/L

EC10 or NOEC for marine water algae:

0.471 mg/L

Additional information

Studies on the acute toxicity of the reaction mass of ammonium sulphate and potassium sulfate and sodium sulphate are not available. However, nitrogen, potassium and sodium are essential elements for organisms and their uptake is actively regulated by the organisms. Ammonium might be assimilated by aquatic plants as a nitrogen source. Thus, an inhibition of algal growth by ammonium, potassium or sodium is not expected. The available data for ammonium sulphate and sodium sulphate support this assumption. In a static test running for 18 days the growth of Chlorella vulgaris was inhibited by 50% at approx. 2700 mg/L ammonium sulphate (Tam and Wong, 1996, cited in OECD SIDS, 2007). However, another study (Thomas et al., 1980, cited in OECD SIDS 2007) has demonstrated that marine phytoplankton is more sensitive to ammonium sulphate than freshwater species. The most sensitive species tested were the dinoflagellates, Gymnodinium splendens and Gonyaulax polyedra, both exhibiting a NOEC growth (17 d) of 0.471 mg/L. Despite these low NOEC values, the high solubility, rapid dissociation and lack of bioaccumulation of ammonium sulphate mean it is unlikely to be harmful to any aquatic algal species. The toxicity of sodium sulphate was tested using the diatom Nitscheria linearis as test organism. The test was terminated after 120 hours and an EC50 of 1900 mg/L based on the growth rate was determined (Patrick et al., 1968, cited in OECD SIDS, 2005).