Abandoned and contaminated land - Environmental Deterioration and Contamination: Problems and their Management - page 86

Liability issues complicate most of the European clean-up activities, e.g., many site
owners of the areas in question refuse to cooperate. European remediation is handi-
capped by the facts that the investigation proceeded fast, implementation is incomplete
and completion is very low. The causes are uncertainties in time requirement and
objectives and the lack of financing.

4 SOIL DETERIORATION OTHER THAN CONTAMINATION

Soil contamination cannot be handled separately from other soil deteriorations.
A complete list of priority soil deteriorations is summarized in the following:

- Loss of soil and land suitable as habitat of ecosystems and agroecosystems;

- Wind and water erosion, landslides;

- Soil sealing;

- Compaction;

- Acidification;

- Organic matter decline;

- Salinization and sodification;

- Desertification;

- Contamination.

Erosion is the loss of soil. When raindrops reach the soil, they detach soil particles.
The degree to which this happens depends on the size and speed of the falling raindrops.
The detached soil particles are subsequently transported by overland water flow. Some
particles fill up soil voids, sealing the soil surface. Erosion occurs when the precipitation
rate exceeds the infiltration rate of the soil.
Soil sealing is the covering of the soil surface with impervious materials as a result
of urban development and infrastructure construction. The term is also used to describe
a change in the nature of the soil leading to impermeability such as compaction (see
next paragraph) by agricultural machinery (European Soil Portal, 2013).
Compaction takes place when pressure is applied to the soil surface. This alters
soil properties such as porosity and permeability. Pores become disconnected and gas
and water movement through soil is impeded, leading to reduced availability of water
and oxygen. Root growth becomes restricted.
Acidification of soil is a process by which the pH of the soil continuously decreases.
The direct cause of acidification is the dominance of H + ions on the negatively charged
binding sites in soil. Protons are derived from proton-donor compounds such as the
ammonium ion from nitrogen fertilizers. Natural acidification is a long-term process,
while anthropogenic one progresses rapidly. Acid soil accelerates soil leaching and
promotes drastic changes in the mobility of elements and ions. It reduces the amount
of nutrients (nitrogen and phosphorus) and causes deficiency in calcium, magnesium
and molybdenum. Some metals mobilizing at low pH (zinc, cadmium, lead, aluminum,
manganese)may reach toxic levels.
Organic matter decline in soil is caused by the unbalance of three properties of
soil: organic matter input, the activity of degrading, mineralizing organisms and the
rate of humus formation. Soil organic matter is available in the form of living and