4.4.3 Acidification of Soil
Natural acidification of the soil can take place during vegetation growth when plants
and trees in the metabolic process form acid compounds to compensate for nutrient
consumption. During decomposition, hydrogen ions are used and pH values begin to
rise again. Artificial soil acidification can occur as a consequence of modern forestry
and farming practices based on harvest withdrawal and immediate replanting. In
such situations, there is not enough time to restore the soil in terms of pH neutralization and a gradual acidification of the soil occurs. Every year, soils receive large
amounts of waste.
Many SOx and NOx emissions come into the soil as H 2 SO 4 and nitric acid,
respectively. The gradual increase of nitrogen, in the form of nitric acid, can have
fertilizing effects, stimulating growth of vegetation including trees and shrubs.
However, nitrogen overload may lead to nitrogen saturation of the soil, when nitrates
can begin to percolate in deep and surface waters.
Another effect of acid deposition and subsequent increased nutrient loading,
organic material, and trace elements is accelerated, eutrophication of watercourses,
and lakes may occur.
Acidification of soils leads to changes in its chemical properties. A typical feature
is the loss of cationic nutrients, such as potassium, calcium, and magnesium, when a
significant decrease in soil pH can be observed. During acidification, there is also an
increased risk for the mobilization of humus and heavy metals (HMs). At low pH,
the release rate of Cd and manganese increases considerably, causing their migration
to deep water, their presence constituting a potential hazard to the aquifer, especially
for the supply of drinking water.
Large amounts of toxic Al are not released equally in all soils in the acidification
process because not all soils contain the same amount of Al-containing minerals.
When the soils are very acidic, the Al is in very high concentrations because of the
adsorption balance between Al
3+ species and the negatively charged root surfaces.
The pH values have other consequences for the soil. Low pH values inhibit the
growth of MOs, fungus being among the injurious organisms of the soil; they are
associated with the roots of plants and support them in the process of mineral
extraction. Destruction of MOs decreases the soil’s ability to breathe (Wang et al.
2015).
4.4.4 Heavy Metals in the Soil
Possible soil pollution with HMs can be caused by infiltration of highly
contaminated water. Investigations made for several decades for a surface infiltration
system on a field study that received rainwater from high traffic streets showed a
significant increase in Cu, Zn, Cd, and Pb concentrations in soil layers.
The excessive content of toxic elements in the environment is associated with the
etiology of a large number of diseases. HMs and their compounds are the main
92
M. Butu et al.
Natural acidification of the soil can take place during vegetation growth when plants
and trees in the metabolic process form acid compounds to compensate for nutrient
consumption. During decomposition, hydrogen ions are used and pH values begin to
rise again. Artificial soil acidification can occur as a consequence of modern forestry
and farming practices based on harvest withdrawal and immediate replanting. In
such situations, there is not enough time to restore the soil in terms of pH neutralization and a gradual acidification of the soil occurs. Every year, soils receive large
amounts of waste.
Many SOx and NOx emissions come into the soil as H 2 SO 4 and nitric acid,
respectively. The gradual increase of nitrogen, in the form of nitric acid, can have
fertilizing effects, stimulating growth of vegetation including trees and shrubs.
However, nitrogen overload may lead to nitrogen saturation of the soil, when nitrates
can begin to percolate in deep and surface waters.
Another effect of acid deposition and subsequent increased nutrient loading,
organic material, and trace elements is accelerated, eutrophication of watercourses,
and lakes may occur.
Acidification of soils leads to changes in its chemical properties. A typical feature
is the loss of cationic nutrients, such as potassium, calcium, and magnesium, when a
significant decrease in soil pH can be observed. During acidification, there is also an
increased risk for the mobilization of humus and heavy metals (HMs). At low pH,
the release rate of Cd and manganese increases considerably, causing their migration
to deep water, their presence constituting a potential hazard to the aquifer, especially
for the supply of drinking water.
Large amounts of toxic Al are not released equally in all soils in the acidification
process because not all soils contain the same amount of Al-containing minerals.
When the soils are very acidic, the Al is in very high concentrations because of the
adsorption balance between Al
3+ species and the negatively charged root surfaces.
The pH values have other consequences for the soil. Low pH values inhibit the
growth of MOs, fungus being among the injurious organisms of the soil; they are
associated with the roots of plants and support them in the process of mineral
extraction. Destruction of MOs decreases the soil’s ability to breathe (Wang et al.
2015).
4.4.4 Heavy Metals in the Soil
Possible soil pollution with HMs can be caused by infiltration of highly
contaminated water. Investigations made for several decades for a surface infiltration
system on a field study that received rainwater from high traffic streets showed a
significant increase in Cu, Zn, Cd, and Pb concentrations in soil layers.
The excessive content of toxic elements in the environment is associated with the
etiology of a large number of diseases. HMs and their compounds are the main
92
M. Butu et al.