Environmental Engineering Reference
In-Depth Information
12.2. The nature of soil pollution
Soil pollution results from human activity, which may be either diffuse or
localized. Diffuse pollution concerns large surfaces along a given depth. Most often,
it results from the excessive use of fertilizers or pesticides for agricultural purposes.
It can also be the consequence of industrial activities in the case of atmospheric
pollution followed by transfer and fallout. Some well-known examples of this are
the acid rains between the US and Canada, the fallouts due to industrial smoke from
facilities, and fallout from incineration facilities, which are known to propagate
dioxine and heavy metals, among other things. Other diffuse pollution may result
from industrial accidents, as in the case of large areas polluted by the radioactive
emanations caused by Chernobyl. Large-scale diffuse pollution will not be
considered in this chapter, which will focus on localized pollution.
Localized pollution may result from accidents in which toxic or hazardous
compounds are poured on the ground due to problems linked to either industrial
processes or transport. Such pollution is clearly visible; it may have serious
consequences for the local population, close environment and infrastructures.
Emergency procedures and correction measures are planned to deal with possible
consequences. Another type of localized pollution can occur due to leak of toxic
liquid compounds from deficient storage facilities or transportation ducts due to
failing maintenance. This kind of pollution, often due to negligence, is more
difficult to detect and may stay unnoticed for a while. Leaks may also come from
uncontrolled or failing waste disposal systems. In this case, the transfer and
infiltration of pollution into the ground over a long period of time may lead to a
significant degree of pollution. The progressive awareness of environmental
challenges and the resulting regulations established in various countries have
allowed us to improve the situation by adopting relevant preventative measures.
This environmental awareness, however, did not exist at the beginning of the
industrial revolution and during the first two thirds of the 20th century, resulting in
problems that are still being faced now in some cases (such as the above-mentioned
Plaine Saint Denis area). This is one of the reasons why inventories of potentially
polluted sites have been carried out by administrative authorities in various
countries.
A brief description of toxic compounds that may contaminate soils and the
industrial activity they are generated from, taken from a methodological guide
prepared by the British Standards Institution in 1988 [BSI 88] is given in
Table 12.1. Note that significantly more detailed tables have been provided since
then [BSI 00]. The 1988 version has been kept here so as to provide a simpler and
more global idea. The data in the table confirm the importance of chemical and
metallurgical industries together with that of transportation activities (see also
[YON 92]). In France, detailed guides are also available on the Web [BRG 00].
