Technical guidance on normal levels of contaminants in Welsh soil : Copper (Cu) : January 2013

Copper (Cu) is an essential micronutrient for the growth of plants and animals, with a reported Earth’s crust abundance of 55 mg/kg and impacts on health are related to deficiency as well as excess. The effects of high Cu concentrations in soil decreasing the uptake of other essential micronutrients by plants are well known. Much of the soil chemistry of Cu is related to sulphur and organic matter. Sulphide minerals (e.g. chalcopyrite CuFeS2) are the main detrital Cu phases in soil in mineralised areas and may result in high Cu concentrations. Copper released during the weathering of these minerals is readily adsorbed and complexed by organic matter, clay minerals and oxides, and co-precipitated with carbonates. Mobility and displacement of Cu in soils is therefore low. High concentrations of Cu in soil can also be associated with coalfields due to enrichment with organic matter during coal formation (resulting from the strong affinity of Cu for organic ligands) and the presence of sulphides in Coal Measure sediments.