Cobalt [Co, 27]
91
13.4 AIR
Cobalt concentration in the atmosphere of the remote region (Antarctica) is <0.12 ng/m 3 ,
whereas air of urban areas contain it up to 3 ng/m 3 (Table 13.1). Very high Co
concentrations may be in the atmosphere of metal industrial regions. Atmospheric
Co deposition in some EU countries is reported to be (in g/ha/yr) as follows: 1.5–6
in the United Kingdom; 5.6–27 in Germany; and 0.19 in Sweden (Kabata-Pendias
and Pendias 1999).
Mean Co contents of two moss species from mountains in Poland are lower (160–180
μg/kg) than in the same moss species form Alaska (410–420 μg/kg). This may suggest that atmospheric Co input is higher in Alaska than in Poland (Migaszewski
et al. 2009).
13.5 PLANTS
In general, Co is taken up and transported in higher plants by the transpiration
flow. However, several soil factors and ability of plants control its phytoavailability.
Relatively low Co 2+ mobility in plants restricts its transport from stems to leaves.
Mobile Co in soils is easily available to plants. Also other Co forms, like bound to
Fe and Mn oxides, are easily phytoavailable, whereas Co fixed by carbonates and
SOM are hardly available to plants (Bhatacharya et al. 2008). Silanpää and Jansson
(1992), after investigating Co in wheat and corn from 30 countries, have stated that
soil texture is the most significant parameter controlling its levels in plants.
Mean Co contents in cereal grains vary within the range of 5–270 μg/kg, being the
lowest in Norway and the highest in Egypt. In Sweden, the Co content in cereal grains is
(in μg/kg) as follows: wheat, 1.1–18; barley, 4.4–40; and oats, 10–300 (Eriksson 2001a).
Range of Co amounts in grass is 60–270 and in clover 100–570 μg/kg. Liming and different mineral fertilizers reduce the Co phytoavailability and create a risk of a low Co
content in fodder plants, which resulted in Co deficiency, mainly in ruminants. Foliar
applications of Co in solutions are effective in the correction of the Co deficiency.
Among various native plants grown in the polluted area of the Northern Europe
(Kola Peninsula), crowberry (Empetrum nigrum) has the highest capacity to accumulate Co, up to 10,510 μg/kg (Reimann et al. 2001). Excess of Co may inhibit some
biological processes (e.g., photosynthesis and respiration) in some plant organisms. In
higher plants, however, there are some evidences that it stimulates chlorophyll formation. Favorable effects of Co on the plant growth, and especially on N-fixation processes are evident. Cobalt is a component of the vitamin B 12 and cobamide coenzyme,
which are involved in the fixation of N 2 in root nodules of legumes. Co coenzymes
have been detected in nonlegumes, but it is unknown whether these compounds are
originated from microorganisms associated with plants. Thus, beneficial effects of Co
on plant metabolisms are not yet understood, and most possible it is cross-linked with
several interactions with other chemical elements (Kabata-Pendias 2011).
Cobalt deficiency inhibits plant growth, mainly of various legumes. Its deficiency
in fodder plants is considered mainly from the viewpoint of ruminants requirement,