Copper [Cu, 29]
101
14.3 WATERS
Median Cu concentration in world ocean water is estimated at 0.25  μg/L and in
river water at 1.48 μg/L (Reimann and de Caritat 1998). However, its concentration
in water varies highly, depending on pollution source and water pH (Table 14.1). Its
world river flux in seawater is estimated at 55 kt/yr (Gaillardet et al. 2003). Yearly
input of Cu to the Baltic Sea is calculated as 1300 t for river water, and as 1200 t for
atmospheric deposition. Up to about 80% of Cu input is from anthropogenic sources
(Matschullat 1997).
The speciation of Cu in water controls biochemical processes and its bioavailability. It occurs in forms of various cations, soluble salts such as carbonates and sulfates, and complexes with organic colloids. Copper species in water depend highly
on the pH. At about neutral pH value in freshwater dominates Cu(OH) 2 , and also
CuCO 3 and Cu 2+ are common (EPA 1986). In seawater, the major Cu species are
Cu(OH)Cl and Cu(OH) 2 (Eisler 1998).
Concentration of Cu in water is in dynamic equilibrium with its contents in
surface-bottom sediments. Copper content in bottom sediments is a good indicator
on its content in water. Average Cu content in river-bottom sediments is estimated
at 9  mg/kg; however, it varies highly, and its content in industrially polluted rivers may be up to about 500  mg/kg (Kabata-Pendias and Pendias 1999). Its mean
content in bottom sediments of San River (Poland) varies from 2 to 48 mg/kg, in
sandy and mule sediments, respectively (Bojakowska et al. 2007). Copper content
of surface-bottom sediments of harbor in Klaipeda (Lithuania) also depends on the
granulometric composition, and is (in mg/kg, average and maximum, respectively)
as follows: in sand 5.5 and 23.4; in mud 21.9 and 29.5 (Galkus et al. 2012). Sediments
of rivers and lakes of some industrial regions may contain elevated amounts of Cu
(in mg/kg, after Kabata-Pendias and Mukherjee 2007):
r India, river near the city Chennai, 760–939
r Russia, lake near the Cu–Ni smelter, <905
r Sweden, lake near smelter area, <2000
r United Kingdom, southwest industrialized region, <590
Surface layer of bottom sediments of rivers and lakes of uncontaminated areas contain Cu within the range 7–107 mg/kg (in Wales and Lebanon, respectively).
Copper contents in stream-bottom sediments of National Park, Montgomery
(Pennsylvania State) were, in 1995, within the range of 10–50 mg/kg (Reif and Sloto
1997). Sediments of Sergipe river estuary (Brazil) contain Cu from 4.92 to 32.7 mg/kg
(Garcia et al. 2011). Cu concentrations in the wetland sediments from the effluent at the
Savannah River site (Aiken, SC) have increased, during a five-year period, from 4 to 205
and 796 mg/kg, respectively, in the organic and floc sediment layers (Knox et al. 2006).
Assessment limits for Cu in sediments are established as follows (in mg/kg): effects
range low, 34; effects range median, 270; probable effect level (PEL), 197; 110; and
86 (EPA 2000, 2013). The Environment Canada sediment-quality guidelines (USGS
2001) gave a bit similar values for Cu in lake-bottom sediments (in mg/kg): threshold
effects level, 35.7; PEL, 197; and probable effect concentration, 149.