Introduction to Contaminated Site Management - Dealing with Contaminated Sites: From Theory Towards Practical Application - page 28

same combinations of contaminants are often found in soils and groundwater. The
risk assessor needs to use this information in order to investigate the site for the
whole contaminant mixture. The exact composition of contaminants in soils and
groundwater, however, may differ. By incomplete combustion of different organic
materials, for example, different mixtures of PAHs are produced, depending on the
type of organic material and combustion characteristics such as temperature.
Second, specific sites, for example sites just outside the city limits of several of
the larger cities around the turn of the nineteenth and twentieth centuries, lent them-
selves to several soil contaminating activities. At these sites, an often incoherent
cocktail of contaminants is present. For these sites, it is more difficult to determine
which contaminants to search for.
1.3.6 Scope of This Topic
A specific class of potentially harmful contaminants found in soil consists of
radioactive contaminants (e.g., Callahan et al. ( 2004 ), who evaluated the human
health risks due to the presence of depleted uranium at a military training site in the
USA). Since radioactive substances are of a different nature and require a different
kind of Risk Assessment, these contaminants do not fall within the scope of this
topic. For the same reason endocrine disruptors (aka: 'hormonally active agents';
see Lintelmann et al. ( 2003 ), who provided an overview of the biochemical and
biological background of endocrine disrupters in the environment) are not consid-
ered in the scope of this topic. Furthermore, no attention will be paid in this topic
to the microbial contaminants , mainly relevant in groundwater, that originate from
both human and animal faeces via sewer leaks, septic tanks and manure disposal,
although these are of great concern for human health (e.g., Celico et al. ( 2004 ), who
found several microbial contaminants, related to pasture and/or manure spreading,
in different carbonate aquifers of southern Italy).
Recently, there has been much attention paid to the impact of nanoparticles in
the environment. Since these nanoparticles are central to many natural processes in
soil and groundwater and in human physiology, they are a potential threat to the soil
ecosystem and human health. Given the limited scope of their use, it is currently
unlikely that they pose a substantial risk to the soil ecosystem and human health
(Colvin 2003 ). However, since the widespread use of nanomaterials will result in
higher concentrations in soils, the future impact is unknown. For the same reasons
that radioactive contaminants and endocrine disruptors require a different kind of
Risk Assessment, nanoparticles are not considered in the scope of this topic.
1.4 Site Characterisation
Site characterisation is an essential step in identifying contaminated sites and, in the
steps that follow, contaminated site management. Therefore, each project involv-
ing contaminated sites needs to begin with a preliminary study of the site under