90
Trace Elements in Abiotic and Biotic Environments
of Łódź (Poland) contain Co up to 100 mg/kg, as effects of contaminations from the
power plant and motor traffic (Jankiewicz and Adamczyk 2007).
The criteria for contaminated land (Dutch List 2013), following Co concentrations in soils and groundwater, are established (in mg/kg, and μg/L) as follows:
uncontaminated, 20 and 20; medium contaminated, 50 and 50; heavily contaminated,
300 and 200.
13.3 WATERS
Cobalt is slightly mobile in terrestrial systems and therefore its C w /C c ratio is very
low, about 0.08 (Gaillardet et al. 2003). In addition, while Co is an in soluble species,
it is easily adsorbed by organic complexes and Fe–Mn hydroxides.
The worldwide concentration of Co in ocean water ranges from 0.001 to
0.02 μg/L (Table 13.1). In Baltic Sea, its concentration is fairly similar, within the
range 0.001–0.07 μg/L (Szefer 2002). Its world river flux to seawater is estimated
as 5.5 kt/yr (Gaillardet et al. 2003). Yearly flux of Co to the Baltic Sea is calculated for 20 t from anthropogenic sources, and 3 t from natural aerial deposition
(Matschullat 1997).
The worldwide mean Co concentration in river water is 0.12  μg/L, within the
range of 0.02–0.43  μg/L. River water of Western Siberia contain Co from 0.2 to
2 μg/L, and its input to the Baikal Lake is 3 t/yr (Vietrov 2002). Concentration of
Co in water of the Kola River (Russia) is (in μg/L) 0.03–0.83 in dissolved phase and
0.003–0.19 in suspended phase (Pekka et al. 2004). Mean cobalt concentrations in
Nordic lakes are (in μg/L) as follows: 0.96 in Norway, 1.4 in Sweden, and 2.4 in
Finland (Skjelkvåle et al. 2001). Surface water around Cu-mine and smelter areas
contain increased Co levels, up to about 6000 μg/L (ATSDR 2002b).
Cobalt in water is present in several species: Co 2+ , Co 3+ , CoCl 2+ , and CoHCO 3
,
and is coprecipitated as CoSO 4 and CoCO 3 . All Co species, but in particulate Co 3+ ,
are adsorbed by mineral and organic particles and are deposited in bottom sediments.
Especially high adsorption capacity have Fe–Mn hydroxide particles. Cobalt content
in bottom sediments is a good information on the water pollution. Average Co content in river-bottom sediments is estimated at 13 mg/kg; however, it varies highly and
in industrially polluted rivers, it may be up to 50 mg/kg. Its mean content in bottom
sediments of San River (Poland) varies from 1 to 8 mg/kg, in sandy and mule sediments, respectively (Bojakowska et al. 2007). Soluble species of radiocobalt may be
released from some nuclear reactors to water, and therefore its contents may increase
in the future (ATSDR 2004b).
Median Co concentrations in both bottled and tap water of the EU countries is
0.023 μg/L, (Birke et al. 2010). Drinking water in the United States contain (at an
average) Co <2 μg/L (ATSDR 2004b).
Aquatic organisms may accumulate elevated amounts of Co. Mussels may contain, in soft tissue, Co up to 900 μg/kg FW, whereas its contents in fish range from 1
to 10 μg/kg FW. Especially high Co levels (<100–2100 μg/kg) were found in planktons (Szefer 2002).