Service Communautaire d'Information sur la Recherche et le Développement - CORDIS

A framework for the classification of the environmental quality for urban soils

It is proposed that the original role of the soil as an element of the environment is adopted as the reference use. Consequently, its environmental quality would be defined as "the mode and capacity of an urban soil to interact with other environmental compartments such as water, air and the biosphere. Any use of the soil by the humans would degrade its environmental quality, at least because it would move it away from its climax. It is well known that agriculture itself that can improve some soil properties in the short term could, in the long run, degrade the environmental significance of the soil. Loss of organic matter (desertification) and salinization are but two of the current threats to European soils that descend from agricultural misuse of the soil resource. Such degradation is even more evident in urban settings where human intervention on soil is dramatic. Diffuse- and point source contamination is the most obvious but mixing with foreign materials, removing and replacing of the soil also contribute heavily to the present status of urban soils.

A priority list should be produced of the possible soil uses having the Environmental Quality - and the properties that define the soil in this role - as a top, reference use. The preparation of a city specific list would help to establish limits for contaminated site remediation. Also, it could certainly help in defining the value of the soils as a commodity in environmental terms:
- the value of traded land could based on its current EQ and on the envisaged EQ after trade;
- damage to the soil could be quantified in terms of EQ loss;
- criteria for protection of the soil would use its EQ as a guiding principle leading to more consistent and stable results.

This systems appears to have the following advantages:
- It can easily be integrated into our DST
- Only 3 classes: easy to understand and adopt.
- Each city can define its top and bottom classes and can define subclasses
- The system can be made to work with minimal amount of information and does not necessarily require harmonization of data and procedures to be implemented. Synthetical grades can in fact carry the same amount of information, even though it is originally expressed through different measurements or units.
- It can be easily upgraded with some expert support

The Minimum Data Set for the evaluation of urban soils quality
The MDS is based on the measurement of a set of parameters, important for the evaluation of urban soil quality, and on the ranking of soils in different soil quality classes in function of the results obtained. Using data from analytical results and from the general descriptors of the urban environment, the MDS allows ranking urban soils on a scale based on their environmental quality.

Three different sets of parameters are considered:
1) Soil parameters.
2) Degradation parameters
3) Descriptors of the urban environment

The two first classes directly use analytical results, giving a quantitative classification of urban soils. This quantification is obtained by attributing to each parameter a score from 1 (worst) to 3 (best conditions). In the first ("Soil") class, the parameters are considered that directly relate to the soil and have a strong influence on its quality, especially for what concerns fertility and mobility of contaminants. The second ("Degradation") class takes into account the parameters that could lead to a depletion of soil functions, with special reference to contaminants. The same conceptual scheme than the table above is applied: a score from 1 (worst) to 3 (best) is assigned to each class of parameters. The presence of extraneous materials and the evidence of mixing processes are also considered as they represent an important visual evidence of man¿s influence on urban soils.

The sum of the points obtained in the first two tables ("Soil" and "Degradation") gives an overall score that allows to fit the soils in one of the following classes of environmental quality:
A) Overall score from 24 to 36: best environmental quality. Soils in this class show characteristics close to the natural ones. No remediation is required and these soils can be safely used for all the purposes, particularly as parks and gardens.
B) Overall score from 12 to 24: average environmental quality. These soils reflect the anthropogenic influence, reflected by a depletion in their environmental quality. These soils are likely to be suitable for construction but should be avoided from being used as parks, especially for children. If this would be the case, the opportunity of a remediation should be carefully considered
C) Overall score from 0 to 12. Worst environmental quality. These soils strongly reflect man's influence; their quality is reduced to the minimum.

Data about the city ecosystem can be incorporated in the classification mostly as correction factors whose value needs to be established according to the specific case and use.

Informations connexes

Reported by

Universita di Torino DIVAPRA
Via Leonardo da Vinci, 44
10095 Grugliasco
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