Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

Measured concentrations in ecosystems

Because Potassium oxide does occur in the environment as Potassium and Oxygen a separate environmental assessment of both the potassium and the Oxygen ion is needed.

Oxygen is the most abundant chemical element by mass in the Earth's biosphere, air, sea and land. Oxygen is the third most abundant chemical element in the universe, after hydrogen and helium.

Potassium is essential constituent and one of the most abundant ions in all animal species. In adult humans, the total body potassium is approx. 3.5 mol (135 g). 98 % of this is located intracellular (150 mmol/l), the extracellular potassium concentration is approx. 4 mmol/l.

Potassium has been measured extensively in aquatic ecosystems. For example, UNEP (1995) reported the concentration for a total number of 75 rivers in North America, South-America, Asia, Africa, Europe and Oceania. The 10th -percentile, mean and 90th -percentile were 0.8 , 3.2 and 6.0 mg/l, respectively. The potassium concentration of topsoils is 0.2-3.3% (Chemical Economics Handbook, 1999), and that of seawater is 380 mg/l (Tait, 1980).

Levels of concern for water quality from anthropogenic exposure, predominantly fertilizers, are never reached (12 mg/l WHO guideline for drinking water), except downstream from potash mines (Weser: 42.0 mg/l; Elbe: 26.1 mg/l). Acidity/alkalinity is measured as pH which is a key parameter in water quality. pH is closely linked to biological productivity in aquatic systems. With dissolved organic acids from soil leaching (Amazonia), a pH of less than 4.0 has been measured. In waters with a high chlorophyll content, the bicarbonate assimilation can result in pH values exceeding quiet commonly 8.5, and even 9.0 at midday (Loire)