194
Trace Elements in Abiotic and Biotic Environments
Mean Mn content of mosses (Hylocomium splendens) from Poland was 245 mg/ kg,
whereas those collected in Southern Alaska was 80 mg/kg (Migaszewski et al.
2009). This indicates its anthropogenic sources. High Mn concentration, within the
broad range of 28–2100 mg/kg, was reported for mosses from Sweden (Berg and
Steinnes 1997).
Manganese exists mainly in two oxidation states in the atmosphere, Mn 2+ and
Mn 4+ . Divalent Mn is a soluble oxidation state, whereas tetravalent Mn is mainly as
a particulate; therefore, Mn 2+ is in higher concentrations in rainwater (Willey et al.
2009). Concentrations of Mn
2+ and SO
2
4
are significantly correlated in some rain
water, as Mn stimulates the catalytic oxidation of SO 2 . Manganese in air also reacts
with soluble NO 2 present in rainwater.
Concentration of Mn in rainwater collected in Sweden (in 1999) varied from
0.5 to 3.1 μg/L, and was fairly similar to its contents in rainwater from the Kola
Peninsula, within the range of 0.45–6.1 μg/L (Eriksson 2001a).
26.5 PLANTS
Adequate levels of available Mn are necessary for plants. Mn uptake by plants is
both metabolically controlled, and due to passive absorption, especially at its high
content in soils. Complex interactions between roots and microorganisms, which
often resulted in the oxidation of soluble Mn 2+ into unavailable Mn 3+ or Mn 4 , have
presumably an impact on the Mn phytoavailability (Marschner 2005). Deficiency of
Mn may occur in certain crop plants, on neutral and calcerous soils.
Manganese is easily transported within plants, which indicates that it is not bound to
insoluble organic ligands (Peng et al. 2008). However, when Mn is accumulated in old
leaves or sheaths, it is not translocated to young organs, under its deficiency. Generally,
the most readily phytoavailable Mn is in acid, flooded, and SOM reach soils.
The most important Mn function in plants is related to the oxidation–reduction
processes. It is a specific component of two enzymes, arginase and phosphotranferase, and may substitute Mg in other enzymes. It participates in the photosynthesis,
being involved in O 2 and electron transport systems. It is also involved in the NO
2
reduction process, and thus may have an impact on the N assimilation by plants.
Chloroplasts are the most sensitive cells to the Mn deficiency, of which first symptoms occur as interveinal chlorosis. Mn-deficient plants have retarded growth, and
lower resistance to diseased and climatic impacts. The most sensitive crop plants to
Mn deficiency are oats, peas, sugar beet, and some fruit trees. The correction of Mn
deficiency in crop plants may be done by both soil and foliar applications. The toxicity of Mn to some crop plants may be expected on soils with pH < 5.5, with high Mn
levels, and poorly drained soils. Activities of some enzymes and hormones in plants
are limited under an excess of Mn. Legumes appear to be very sensitive to excess
Mn, due to affected rhizobia nodules, and thus lower the N fixation. Also, potatoes
are easily affected by excess Mn. Plant tolerance to high Mn contents in soils is
related to several metabolic processes, such as (1) oxidizing power of plant roots,
from Mn to MnO 2 ; (2) complexation of Mn by low-molecular-weight compounds;
(3) Mn entrapment in nonmetabolic centers; (4) Mn accumulation in roots; and
(5) interactions with other elements, especially with Ca, Fe, Al, and NH 4 .
Trace Elements in Abiotic and Biotic Environments
Mean Mn content of mosses (Hylocomium splendens) from Poland was 245 mg/ kg,
whereas those collected in Southern Alaska was 80 mg/kg (Migaszewski et al.
2009). This indicates its anthropogenic sources. High Mn concentration, within the
broad range of 28–2100 mg/kg, was reported for mosses from Sweden (Berg and
Steinnes 1997).
Manganese exists mainly in two oxidation states in the atmosphere, Mn 2+ and
Mn 4+ . Divalent Mn is a soluble oxidation state, whereas tetravalent Mn is mainly as
a particulate; therefore, Mn 2+ is in higher concentrations in rainwater (Willey et al.
2009). Concentrations of Mn
2+ and SO
2
4
are significantly correlated in some rain
water, as Mn stimulates the catalytic oxidation of SO 2 . Manganese in air also reacts
with soluble NO 2 present in rainwater.
Concentration of Mn in rainwater collected in Sweden (in 1999) varied from
0.5 to 3.1 μg/L, and was fairly similar to its contents in rainwater from the Kola
Peninsula, within the range of 0.45–6.1 μg/L (Eriksson 2001a).
26.5 PLANTS
Adequate levels of available Mn are necessary for plants. Mn uptake by plants is
both metabolically controlled, and due to passive absorption, especially at its high
content in soils. Complex interactions between roots and microorganisms, which
often resulted in the oxidation of soluble Mn 2+ into unavailable Mn 3+ or Mn 4 , have
presumably an impact on the Mn phytoavailability (Marschner 2005). Deficiency of
Mn may occur in certain crop plants, on neutral and calcerous soils.
Manganese is easily transported within plants, which indicates that it is not bound to
insoluble organic ligands (Peng et al. 2008). However, when Mn is accumulated in old
leaves or sheaths, it is not translocated to young organs, under its deficiency. Generally,
the most readily phytoavailable Mn is in acid, flooded, and SOM reach soils.
The most important Mn function in plants is related to the oxidation–reduction
processes. It is a specific component of two enzymes, arginase and phosphotranferase, and may substitute Mg in other enzymes. It participates in the photosynthesis,
being involved in O 2 and electron transport systems. It is also involved in the NO
2
reduction process, and thus may have an impact on the N assimilation by plants.
Chloroplasts are the most sensitive cells to the Mn deficiency, of which first symptoms occur as interveinal chlorosis. Mn-deficient plants have retarded growth, and
lower resistance to diseased and climatic impacts. The most sensitive crop plants to
Mn deficiency are oats, peas, sugar beet, and some fruit trees. The correction of Mn
deficiency in crop plants may be done by both soil and foliar applications. The toxicity of Mn to some crop plants may be expected on soils with pH < 5.5, with high Mn
levels, and poorly drained soils. Activities of some enzymes and hormones in plants
are limited under an excess of Mn. Legumes appear to be very sensitive to excess
Mn, due to affected rhizobia nodules, and thus lower the N fixation. Also, potatoes
are easily affected by excess Mn. Plant tolerance to high Mn contents in soils is
related to several metabolic processes, such as (1) oxidizing power of plant roots,
from Mn to MnO 2 ; (2) complexation of Mn by low-molecular-weight compounds;
(3) Mn entrapment in nonmetabolic centers; (4) Mn accumulation in roots; and
(5) interactions with other elements, especially with Ca, Fe, Al, and NH 4 .