99
Copper [Cu, 29]
are SOM, dissolved organic carbon, dissolved organic matter (DOM), Fe minerals,
and pH. The overall solubility of both cationic and anionic forms of Cu decreases at
pH 7–8 (Ponizovsky et al. 2006). However, soil clay fraction has the highest impact
on Cu behavior.
Precipitation of CuCO 3 , especially in calcareous soils, is a main process affecting the Cu activity in most soils. Attenuation of Cu mobility may also result
from the Cu–Ca substitution in calcites present in calcareous soils, or from the
precipitation of Cu–carbonate compounds in other soils (Ma et al. 2006). Organic
Cu complexes also have a crucial impact on its bioavailability, and on migration
within soil profile. Great impact on Cu behavior in soils have all species and
minerals of Fe (Cornell and Schwertmann 2003; Contin et al. vide DąbkowskaNaskręt 2009).
Phytoavailability of Cu depends on its amounts in soils, and on the molecular
weight of Cu complexes. There are some opinions, however, that its availability to
plants is influenced by Cu species and not by the total content (Allen 1993). Mobility
and phytoavailability of Cu is reduced by the presence of Fe–Al–oxyhydroxide
coating colloids; oxyhydroxide particles of Fe, Mn, and Al; and by DOM. However,
the impact of DOM from sewage sludge is reported to mobilize Cu in soils
(Ashowrth and Alloway 2004). Organic compounds of a low molecular weight,
from the decay of organic residues, and those added to soils, mainly with sewage
sludge, highly increase its mobility and availability to plants (Bahaminyakamwe
et al. 2006). Forest litter (especially its compound—tannin) also increases the Cu
solubility, but with time, it leads to the reduction of mobility (Karczewska et al.
2013). Chemical speciation of Cu in sewage sludge controls its bioavailability and
toxicity to plants (Fjällborg and Dave 2003). Copper added to soils with sludge
is easily phytoavailable and very mobile, and therefore may cause ground and
surface water pollutions. Average Cu concentration in urban wastewater (UWW)
is 0.2 mg/L, and its presence is very common, up to 75% of investigated UWW
from the United Kingdom (ICON 2001). Its content in sewage sludge applied to
agricultural land in Germany is 305 mg/kg (average) and in the United Kingdom is
373 mg/kg (median) (ICON 2001).
Soil contamination by Cu has been studied for several decades and a large database has been already presented. There are several significant sources, such as fertilizers, sewage sludge, manure, agrochemicals, polluted irrigation waters, industrial
wastes and emissions, and urban pollution. Highly increased Cu levels are in soils
surrounding Cu mines and smelters (Table 14.2). Mean Cu content of soil, along the
high traffic road in Poland, is 65.23 mg/kg (the highest 195.76), and at the 10 km
distance, it is 12.55 mg/kg (the highest 21.30) (Niesiobędzka 2012).
Agricultural input of Cu to soils is significant in some countries. In the EU
countries, it varies (in g/ha/yr) from 29 in the Czech Republic to 2771 in Italy.
Minus load charge to farmland soils was noticed only in Switzerland and Norway.
The highest loads of Cu were observed in sludged and vineyard soils as 3,905 and
13,923 g/ha/yr, respectively (Eckel et al. 2005). Also, soil amended with poultry
litter accumulated much Cu, up to 1400 mg/kg (Nachtigall et al. 2007). FernandezCalvino et al. (2008) reported that increased Cu levels, 246 mg/kg, in vineyard soils
increased its contents, up to 209 mg/kg, in river-bottom sediments. The maximum