Boron [B, 5]
43
Soil contamination with B is considered now as a widespread agro-environmental
problem. Therefore, the phytoremediaton of such soils has been investigated. The
highest B removal from soils by crop plants is with lucerne (350 g/ha) and sugar beet
(300/ha) (Shorrocks 1997). Poplar (Populus sp.) accumulated up to 845 mg B/kg,
and is suggested by Robinson et al. (2007) to remove excess B from soils.
Boron interacts in the uptake of other nutrients by plants because it has an
influence on the membrane permeability and cell colloids (Goldbach et al. 2007).
Mechanisms of these reactions are still not well understood. The possible antagonisms with some elements, such as Cu, Cr, Mo, and Mn, may be the indirect effects
of increased demands for these micronutrients, due to the increased plant growth.
Other interactions are partly explained as follows:
r B–Zn: At low levels of available Zn plants may uptake B to toxic levels in
plants, especially in roots.
r B–Si: Antagonism is an effect of competition of silicate ions for adsorption
sites of B.
r B–Ca: Interrelationship is relatively often observed. It is mainly limeinduced B deficiency in acid soils. Therefore, toxic effects of B may be
reduced by adding Ca to soils, especially in the form of CaSO 4 .
r B–P: Interactions occur in soil media where P ions decrease B mobility. The
uptake and distribution of P is dependent on the B concentration because B
increases P immobility in roots. These two elements influence the integrity
of cell membrane, thus their imbalances may lead to the aberration in their
uptake.
Other interactions are also observed with elements such as K, N, and Al. It may be,
however, a secondary effect associated with some physiological disorders in plants.
7.6 HUMANS
Amount of B found in the human body (average 70 kg) is 18 mg (Emsley 2011). In
the human tissues, its concentrations are as follows (in mg/kg FW): in the kidneys,
0.6; in the lungs, 0.6; in the lymph nodes, 0.6; in the blood, 0.4; in the liver, 0.2; in
the muscles, 0.1; in the testes, 0.09; in the brain, 0.06 (Health Canada 1991), and in
the rib bone, ≤0.65 (Zaichik et al. 2011).
Boron, in intracellular and extracellular spaces, is categorized as a possible essential nutrient for humans, but this has not been yet directly proven (Coughlin and
Nielsen 1999; EPA 2008a; Meacham et al. 2010). Nielsen (2008) suggests that in
recent years the focus on B has shifted from toxicological effects and dietary recommendations to nutritional essentiality and biochemical mechanisms of action.
Boron plays an important role in mineral and hormonal metabolisms, cell membrane functions, and enzyme reactions. Boron also affects osteoporosis (is involved
in Ca and bone metabolism), heart trouble, paralysis, diabetes, and senility. Its
effects are more marked when cholecalciferol (vitamin D 3 ) and Mg are deficient.
Boron is involved in biochemical indices associated with the metabolism of other
nutrients, including Ca, Cu, N, and cholecalciferol, in the synthesis of extracellular
43
Soil contamination with B is considered now as a widespread agro-environmental
problem. Therefore, the phytoremediaton of such soils has been investigated. The
highest B removal from soils by crop plants is with lucerne (350 g/ha) and sugar beet
(300/ha) (Shorrocks 1997). Poplar (Populus sp.) accumulated up to 845 mg B/kg,
and is suggested by Robinson et al. (2007) to remove excess B from soils.
Boron interacts in the uptake of other nutrients by plants because it has an
influence on the membrane permeability and cell colloids (Goldbach et al. 2007).
Mechanisms of these reactions are still not well understood. The possible antagonisms with some elements, such as Cu, Cr, Mo, and Mn, may be the indirect effects
of increased demands for these micronutrients, due to the increased plant growth.
Other interactions are partly explained as follows:
r B–Zn: At low levels of available Zn plants may uptake B to toxic levels in
plants, especially in roots.
r B–Si: Antagonism is an effect of competition of silicate ions for adsorption
sites of B.
r B–Ca: Interrelationship is relatively often observed. It is mainly limeinduced B deficiency in acid soils. Therefore, toxic effects of B may be
reduced by adding Ca to soils, especially in the form of CaSO 4 .
r B–P: Interactions occur in soil media where P ions decrease B mobility. The
uptake and distribution of P is dependent on the B concentration because B
increases P immobility in roots. These two elements influence the integrity
of cell membrane, thus their imbalances may lead to the aberration in their
uptake.
Other interactions are also observed with elements such as K, N, and Al. It may be,
however, a secondary effect associated with some physiological disorders in plants.
7.6 HUMANS
Amount of B found in the human body (average 70 kg) is 18 mg (Emsley 2011). In
the human tissues, its concentrations are as follows (in mg/kg FW): in the kidneys,
0.6; in the lungs, 0.6; in the lymph nodes, 0.6; in the blood, 0.4; in the liver, 0.2; in
the muscles, 0.1; in the testes, 0.09; in the brain, 0.06 (Health Canada 1991), and in
the rib bone, ≤0.65 (Zaichik et al. 2011).
Boron, in intracellular and extracellular spaces, is categorized as a possible essential nutrient for humans, but this has not been yet directly proven (Coughlin and
Nielsen 1999; EPA 2008a; Meacham et al. 2010). Nielsen (2008) suggests that in
recent years the focus on B has shifted from toxicological effects and dietary recommendations to nutritional essentiality and biochemical mechanisms of action.
Boron plays an important role in mineral and hormonal metabolisms, cell membrane functions, and enzyme reactions. Boron also affects osteoporosis (is involved
in Ca and bone metabolism), heart trouble, paralysis, diabetes, and senility. Its
effects are more marked when cholecalciferol (vitamin D 3 ) and Mg are deficient.
Boron is involved in biochemical indices associated with the metabolism of other
nutrients, including Ca, Cu, N, and cholecalciferol, in the synthesis of extracellular