Copper :: all ecosystems

Key Concerns

Copper is an essential element for all biota, therefore any adverse effects must be balanced against its essentiality. This means that for all organisms, there will be range of optimal copper concentrations. Exposure to copper concentrations outwith this range, will result in adverse effects, due to either copper deficiency, or copper toxicity.

However large variations in inter-species sensitivity and bioavailability of the copper must be taken into account when assessing possible effects. The concentration of total copper is not necessarily indicative of the proportion of bioavailable copper. The bioavailability of copper is determined by various factors, including the chemical speciation of the copper, and the characteristics of the soil, including its pH and the concentrations of inorganic and organic ligands, and competition with other chemical species (Temminghoff et al. 1997; WHO 1998).

Ecosystem specific information

Arable habitats - arable land may have a history of copper applications from the use of fertilisers, including animal manure (Moolenaar et al. 1998). High concentrations of copper can be extremely toxic to plants. General symptoms include chlorotic leaves, early leaf-fall, stunted growth and impaired root development. Plants will subsequently have reduced uptake of water and nutrients, leading to disturbances in metabolism and growth retardation. At the cellular level, copper inhibits a large number of enzymes, and it interferes with several aspects of plant biochemistry (including photosynthesis, pigment synthesis and membrane integrity) and physiology (interference with fatty acids, protein metabolism and inhibition of respiration and nitrogen-fixing processes) (WHO 1998). Laboratory studies have demonstrated effects on nematode communities indigenous to agricultural soil. Exposure to copper concentrations exceeding 50 mg/kg soil caused the disappearance of some nematode taxa (Korthals et al. 2000).

Bogs, wetland and heath - high concentrations of copper can be extremely toxic to plants. General symptoms include chlorotic leaves, early leaf-fall, stunted growth and impaired root development. Plants will subsequently have reduced uptake of water and nutrients, leading to disturbances in metabolism and growth retardation. At the cellular level, copper inhibits a large number of enzymes, and it interferes with several aspects of plant biochemistry (including photosynthesis, pigment synthesis and membrane integrity) and physiology (interference with fatty acids, protein metabolism and inhibition of respiration and nitrogen-fixing processes (WHO 1998).

In wetlands, copper has been found to bind to peat, silts and clays (Lau and Chu 1999; Dierks 2001). Copper bound to wetland sediment has been found to inhibit denitrification, resulting in an increased ammonium concentration in the sediment-water environment (Sakadevan et al. 1999). Copper is taken up by the roots of heather (Calluna vulgaris), with root to shoot transfer also reported. Copper was phytotoxic to heather, as evident by decreased shoot length, and reduced shoot and root biomass, with exposure to 100mg/l copper solutions killing 50% of exposed seedlings (Monni et al. 2000).

Coastal and rocky habitat –  copper has been shown to exert adverse reproductive, biochemical, physiological and behavioural effects on a variety of saltwater organisms at concentrations (WHO 1998). However, large variations due to differences in bioavailability of the copper, and inter-species sensitivity must be taken into account when assessing possible effects. The concentration of total copper is not necessarily indicative of the proportion of bioavailable copper. The bioavailability of copper is determined by various factors, including the chemical speciation of the copper, and the properties of the environment (water salinity, pH and concentrations of suspended particles, dissolved organic matter and inorganic ligands) (US EPA 1984; WHO 1998).

Effects on growth of marine algae have been reported following exposure to copper concentrations ranging from 114 to 610 µg/l. For marine invertebrates, 96h-LC50 values for range from 29 µg/l (bay scallop) to 9400 µg/l (fiddler crab). For marine fish, 96h-LC50 values for range from 60 µg/l (chinook salmon) to 9400 µg/l (grey mullet) (WHO 1998).

Grassland -  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).

Woodland and hedgerow – there is a paucity of data on the effects of cobalt on species indicative of woodland or hedgerow ecosystems. 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).