Soil quality

Contenido
1 STATE OF THE ART 3
1.1 Definition and importance 3
1.2 Characterization 4
1.3 Soil´s global problematic: desertification 4
1.4 Soil quality indicators 6
2 SOIL CONTAMINATION 7
2.1 Sources of contamination 7
2.2 Remediation techniques 7
2.3 Importance of knowing the contamination degree in soils 8
2.4 Sampling 9
2.5 Monitoring 9
3 PORTUGUESELEGISLATION ON CONTAMINATED SOILS 10
4 CONCLUTIONS 10
5 BIBLIOGRAPHY 10

STATE OF THE ART
Definition and importance
According to the United States Department of Agriculture, soil is defined as the unconsolidated mineral or organic material on the immediate surface of the Earth that serves as a natural medium for the growth of land plants. Another definition is a natural body comprised of solids(minerals and organic matter), liquid, and gases that occurs on the land surface, occupies space, and is characterized by one or both of the following: horizons, or layers, that are distinguishable from the initial material as a result of additions, losses, transfers, and transformations of energy and matter or the ability to support rooted plants in a natural environment.
Figure 1. Soil´shorizonts
The soil´s formation factors are climate, organisms, rock, relief and time, and so most soils have a distinct profile or sequence of horizontal layer; resulting from the processes of chemical weathering, eluviations and organic decomposition.
Figure 2. Basic components of an average soil. Source: www.physicalgeography.net
The constituent parts of soil are organic matter, mineral matter,water, dissolved substances, air and living organisms. All these properties together come to form an unique soil profile made up of layers, that are called horizons. Up to five layers can be present in a typical soil: O, A, B, C, and R horizons. In figure 1 an example of soil´s horizons is shown, and in figure 2, the average percentage distribution of the soil´s components is presented.
Soil canprovide information on the geological, climatic and biological history of the place where it is sampled. Moreover, the studying and characterizing the soils has to do with the fact that soil is a very important natural resource since it integrates all other parts of the ecosystems, it is the medium for plants to grow and so for food and other materials to grow. It is the source of constructionmaterials, and it plays a huge part in the natural cycles of matter because it filters water, decomposes waste, stores heat and exchanges gases.
According to the United Nations Environmental Program, concerning soil, the health of soils and their capacity to process carbon, nutrients, wastes, toxins, and water are important factors for Earth’s ability to minimize adverse environmental effects. It´sknown that it will be impossible to meet the planet’s nutritional demands without seriously reforming agricultural land, and ecosystem management practices that nowadays are leading to global problems such as desertification.
Characterization
Characterization data is the key piece to know how an ecosystem works. Knowing the properties of soil horizons, it can be predicted how fast water willmove through them. Soil properties also tell whether the soil has the potential to store enough water to keep plants growing, to withstand a flood, and to provide the right combinations of chemicals to plants to grow.
Some of the parameters measures during the characterization studies are described in the following table. It should be noticed that the description of these parameters is morefocused on their importance when applying a remediation technique.
Table 1. Soil parameters measured in characterization studies.
Parameter | Description |
Particle size | The most important components are clay (<0.002 mm), sediments (0.002-0.05 mm) and sand (0.05-2.00 mm). It is important to take in count this parameter given the fact that the ratio area/volume from the different particle...