Cobalt in soil is retained by oxides, such as iron and manganese oxide, crystalline materials including aluminosilicates and goethite, and natural organic substances found in soil. In clay soils, the adsorption may be due to ion exchange at the cationic sites on clay with either simple ionic cobalt or hydroloysed ionic species such as cobalt hydroxide (ATSDR 1992).
There is a paucity of data on the effects of cobalt on species indicative of terrestrial ecosystems.
Ecosystem specific information
Arable habitats - increased cobalt concentrations (up to 0.34 mg/kg) have been reported in arable soil following the application of fertiliser, and in soils which received zero tillage, compared to soils which received conventional tillage. The concentrations of cobalt in the arable soil were correlated with organic matter content and soil pH (Lavado et al. 1999).
Bogs, wetland and heath - there is a paucity of data on the effects of cobalt on species indicative of bog, wetland or heathland ecosystems, although the effects of cobalt on two plants from waterlogged paddy fields have been reported. Ninety six hour EC50 values for growth of Spirela polyrhiza and Azolla pinnata were 0.135 and 0.241 mg/l, respectively. These values correspond to cobalt concentrations in plant tissue of 589 and 694 µg/kg (Gaur et al. 1994).
Woodland and hedgerow – cobalt has been reported to be adsorbed by epiphytic lichens and moss, although such deposition has decreased with increasing air quality (Palmieri et al. 1997).
|Critical Load/ Level|
No estimate available