Abandoned and contaminated land - Environmental Deterioration and Contamination: Problems and their Management - page 87

dead organisms and humus from crop residues, compost, animal manures and other
organic materials. Organic matter is regarded as a vital component of a healthy soil; its
decline in Europe is significant: about 10% compared to the total fossil fuel emissions.
Soil organic carbon content is mostly affected by climate, soil texture, soil hydrol-
ogy, land use and vegetation. Changes in natural or anthropogenic factors such as
global warming increase the rate of soil decay. Global warming may increase degrada-
tion rate and mineralization and decrease durable organic matter (humus) content in
the soil.
Loss in humus content results in reduced nutrient binding capacity, deteriorated
texture and structure, impaired water and air regime, as well as lower buffering
capacity against stress such as lack of nutrients, increased temperature, drought and
acidification. In summary it leads to deteriorated terrestrial habitat. Erosion, deflation,
compaction and other soil deterioration processes pose increased risks in low humus
soils. Topsoil eroded by wind and rain jeopardizes efforts to increase food production,
impairs soil quality, increases the risk of flooding and undermines efforts to reduce
carbon emissions in many European countries.
Salinization is the accumulation of water-soluble salts in the soil specifically those
containing the ions K + ,Ca 2 + ,Cl - ,SO 2 4 ,CO 2 3 , HCO 3 , and Na + . Salts are dissolved
and transported by water. When water evaporates, salts precipitate in a crystalline
form. The accumulation of sodium in soil is also called sodification . Both salinization
and sodification may be natural or anthropogenic processes.
Desertification is the persistent degradation of dryland ecosystems due to varia-
tions in climate and human activities. Home to a third of the human population in
2000, drylands occupy nearly half of earth's land area. In drylands, water scarcity
limits the production of crops, forage, wood and other services ecosystems provide to
humans. Drylands are therefore highly vulnerable to increases in human pressures and
climatic variability, especially sub-Saharan and Central Asian drylands but Europe is
also exposed to desertification (UNCCD, 2013).
Contamination of soil and its management is the main topic of this topic; here we
give a short definition to clarify the types of contamination which should be taken into
consideration and managed. Soil contaminating chemical substances may be natural
and man-made chemicals. One part of these chemicals is hazardous and present in a
risky concentration. Another part is not hazardous, but present at a place where they
are not supposed to be naturally or in a concentration which is not natural and there-
fore not acceptable. Contaminants cause deterioration in soil health and services and
disturbances in uses by the ecosystem and humans. A special problem is caused by the
mixtures of contaminants due to the dependence of their mobility and bioavailability
on environmental conditions. Changes in adverse effects and risks of contaminating
chemicals in association with local, regional, or global environmental changes are
usually difficult to predict.
Decline in soil biodiversity is the result of soil deterioration, the reduction of the
soil's capacity to provide a habitat for soil living organisms. Decline in biodiversity
means the reduction of forms of life in the soil ecosystem, in terms of both quan-
tity and variety. Biodiversity denotes the number of distinct species (species richness)
and their proportional abundance (species distribution) present in a system, but may
be extended to encompass phenotypic (expressed), functional, structural or trophic
diversity (European Soil Portal, 2013).