Groundwater-Related Risk Assessment - Dealing with Contaminated Sites: From Theory Towards Practical Application - page 756

for contaminants, this is, as a pathway , and not from the perspective of a groundwa-
ter body as a protection target. In Rolle et al. ( Chapter 19 of this topic), a detailed
description is given of the contaminant transport processes in the water-saturated
soil zone, and the relevant mathematical equations and models.
Human health risks due to the consumption of contaminated drinking water orig-
inating from groundwater very much relate to the risks associated with other human
exposure pathways. Therefore, these human health risks have been incorporated in
the “Human Health Aspects (Part III)” the “Human Health Protection” (see Chapter
11 by Elert et al., this topic). For the same reasons of compatibility, risks for the
groundwater ecosystem have been described in the “Ecological Aspects (Part IV)”
the “Ecological Protection” (see Chapter 14 by Posthuma and Suter, this topic)
from a generic perspective; Rutgers and Jensen ( Chapter 15 of this topic) from a
site-specific perspective).
Water that is present in the water-unsaturated upper soil layer, that is, the pore
water, is generally not considered as a protection target. However, it plays a very
important role in Human Health Ecological Risk Assessment and Food Safety,
since generally the contaminants available in the pore water are those most rele-
vant for human health, soil ecology health quality of vegetables. Therefore, the Risk
Assessment aspects with regard to human health risks and ecological risks in rela-
tion to the pore water are implicitly incorporated in those chapters that focus on
these protection targets, namely, McLaughlin et al. ( Chapter 8 of this topic) and
Trapp and Legind ( Chapter 9 of this topic) with regard to the uptake in vegetables
of metals and organic contaminants, respectively, and Hodson et al. ( Chapter 16 of
this topic) for a description of bioavailability with regard to ecological effects.
Another important aspect with regard to the water-unsaturated upper soil layer is
that the great majority of groundwater enters the aquifer as infiltrating rain water and
melting snow via this layer. During passage through this water-unsaturated upper
soil layer, the water quality will definitely change. In case of contaminated soils,
infiltrating water will be loaded with contaminants, resulting in contaminants leach-
ing into the groundwater. In the case of clean soils, however, contaminants may
be filtered out of the infiltrating water in the unsaturated soil layer. Therefore, the
pore water, analogous to the groundwater, is considered to be a means of trans-
port for contaminants ( pathway ) in the “Ground water-Related Aspects (Part V)”
'Groundwater-Related Risk Assessment'. Or, in other words, the pore water is
considered from the perspective of contaminant leaching to the groundwater. In
Mallants et al. ( Chapter 18 of this topic), a detailed description is given of leach-
ing from the unsaturated upper soil layer into the saturated soil zone, along with the
relevant mathematical equations.
In addition to the important roles of pore water and groundwater as pathways, the
focus will also be on the groundwater as a protection target in the present chapter.
Note that no attention is paid in this topic to the microbial contaminants 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 pollutants, related
to pasture and/or manure spreading, in different carbonate aquifers of southern