224
Trace Elements in Abiotic and Biotic Environments
Nickel is considered as a serious pollutant that is released from metal-processing
plant and from the combustion of coal and oil. Sewage sludge and some P fertilizers
are also important sources of Ni in agricultural soils (Table 29.2). Some municipal
sludges of America cities contain Ni up to 800 mg/kg, with a median value of 195 mg/kg
(ATSDR 2002b). Application of sludge to soils usually increases the Ni mobility, due
to its complexation with dissolved OM. In soils contaminated with Ni, processes of
OM mineralization are disturbed and the activity of some enzymes, such as dehydrogenases, urease, and phosphatases, is decreased (Wyszkowska et al. 2008).
The Ni balance in soils of crop farms in the EU countries was estimated (in g/ha/yr)
from –3.3 in Denmark to 33 in France (Eckel et al. 2005). Emission from the Ni
industry in Russia has affected the elevated Ni levels in soils of Norway, up to about
1400 mg/kg of HNO 3 -extractable Ni (Alamås et al. vide Kabata-Pendias 2011). The
phytoremediation of Ni-contaminated soils has been recently broadly studied, with
promising effects (Chaney et al. 2005).
29.3 WATERS
The mean nickel concentration in ocean waters is given within the range of 0.6–1.7
μg/L (Table  29.1). There is also other estimation, such as 0.1–3.0  μg/L (ATSDR
2002b). The world riverine flux of Ni is given as 305 kt/yr (Gaillardet et al. 2003).
Its flux to the Baltic Sea is estimated to be 400 t/yr (Matschullat 1997). Although Ni is
slightly mobile in water, its amount in rivers may vary from 0.2 to 27 μg/L, what reflex
its variable sources, mainly anthropogenic. Water of Nordic lakes has fairly similar Ni
concentrations, which are as follows (mean in μg/L): 7.1 in Finland, 5.7 in Sweden,
and 3.2 in Norway. In the lakes of the Kola Peninsula, Ni contents of water average at
50.4 μg/L (Skjelvåle et al. vide Kabata-Pendias and Mukherjee 2007).
Nickel does not remain long in aquatic environments as soluble species, because it
is easily adsorbed by the suspended matter and Fe–Mn hydroxides, and is deposited
in bottom sediments. Nickel solubility decreases at pH between 9 and 11.5. Thus, the
addition of some hydroxide compounds will stimulate its precipitation (Chen 2013).
Also the stage of oxygen saturation has significant impact on the Ni concentration in
water (Vignati vide Kabata-Pendias and Mukherjee 2007).
The mean Ni concentration in rainwater is about 1 μg/L, whereas in contaminated
regions, it may be up to 60 μg/L (Reimann and de Caritat 1998). In atmospheric precipitation over the Baltic Sea, Ni concentrations vary between 0.9 and 19.7 μg/L, whereas
rainwater over the Kola Peninsula contains Ni within the range of 0.1–57 μg/L, in
remote and polluted regions, respectively. The average Ni content of rainwater collected in Sweden is 0.34 μg/L, and the maximum is 0.56 μg/L (Eriksson 2001a).
Rainwater collected in Canada contains Ni at the concentration of <1.5 μg/L (ATSDR
2002b). Several Ni species have been identified in rainwater, mainly in complexes with
2+
anions, such as OH , SO , Cl , and HCO 3 . Most often they occur as Ni(H O) 6 .
4
2
The median Ni concentrations in both surface water and groundwater of uncontaminated regions are in the range of 0.5–6 μg/L (ATSDR 2002b), whereas in the
industrial region of Uzbekistan the following amounts of Ni are reported: surface
water –30, and well water at 8 m depth –120 μg/L, respectively (Galiulina et al. vide
Kabata-Pendias and Pendias 1999).