1 General approach
SOURCEč PATHWAY č RECEPTOR/TARGET
The first step of the risk assessment is the problem identification, to be seen as the source characterisation. The objectives of the problem identification is to answer to the questions:
2 Types of sources
Damage of soil functions and the potential contamination of water resources can be generated by diffuse and/or localised sources.
The main diffuse sources of soil contamination are atmospheric deposition of acidifying and eutrophying compounds or potentially harmful chemicals, deposition of contaminants from flowing water or eroded soil itself, and the direct application of substances such as pesticides, sewage sludge, fertilisers and manure.
Soil contamination from localised sources is often related to industrial plants non longer in operation, past industrial accidents and improper municipal and industrial waste disposals.
Pollution can also be related to accidents or chronic emissions of pollutants in the environmental media.
Another distinction can be done between primary (i.e. tanks) and secondary sources of contamination (i.e. soils contaminated by sludge generating groundwater contamination by leakage).
3 Tools for identifying risk sources
To assess the extend of the contamination at national or European levels, inventories of localised contaminated sites are conducted on a local or regional levels. Most of the European States have now an estimation of the number of point sources of contamination (see chapter 5). Some are regularly updated.
To qualify and quantify the risks due to contamination sources, there is a need to establish whether contamination is present, at what concentrations and in what media. A phased approach is generally seen as providing the required data in the most cost-effective and efficient manner.
3.3 Use of a Site Conceptual Model
The step-by-step approach is in general based on a site conceptual model presenting the sources, pathways and receptors to be taken into consideration for the site risk assessment. For a better understanding of the site problem, separation between primary and secondary sources can be done.
4 Site and sources characterisation
The aim of the site investigation is to provide appropriate and reliable data against which to assess risks to chosen receptors, which may include: i) humans, ii) water resources, iii) ecosystems (fauna and flora), iv) buildings and structure. Therefore, the step-by-step site investigation should be conducted to meet the risk assessment objectives.
Depending on the situation encountered, site can be considered as an unique source or be composed by several sources (tanks, landfill, contaminated soils).
In particular, for the source characterisation, data on physical and chemical characteristics of contaminants, including their spatial distribution and expected transport and fate are required.
Methodologies for data collection include: i) desk-based studies, ii) general guidance on site investigation methodology, iii) sampling techniques (intrusive or non-intrusive), iv) non-intrusive investigation techniques (e.g. geophysics), v) analysis (both on site and laboratory), vi) data presentation.
4.3 Limitations of the risk sources characterisation
As for all steps of site investigation related to risk assessment objectives, limitations will be linked to:
The objective is to provide sufficient information on sources, pathways, receptors and other site-specific characteristic to permit risk assessments with a reasonable level of uncertainties to enable the selection of appropriate remedial and management actions.
5 Situation at the European level
5.1 Number of sites
The European Environment Agency has done an estimation of the number of contaminated sites. The European Countries currently conduct different types of inventories. Estimations are related to potentially contaminated sites or known contaminated sites in relation with industrial, waste treatment or military activities. Table 29 shows the situation in 2000.
Important differences are identified due to:
5.2 Types of activities
Effects of industrial activities that pose a risk to soils and groundwater resources and the spectrum of the various polluting activities vary between countries. But in the countries analysed, there is a broad common picture of the main soil-polluting activities. A direct quantification of hazardous substances input into soil is almost impossible though.
Source: EIONET priority data flow; September 2003. For DK, GE, LI, NL, ES:
Pilot EIONET data flow; January 2002; for RO: data request new EEA member
countries, February 2002.
NB: 2003 data not yet published, subject to validation
Notes: (a) Switzerland: ‘Municipal waste disposal’ also include ‘Industrial waste disposal’; ‘former military sites’ also include active military sites and shooting ranges.
(b) Spain: ‘Municipal waste disposal’ also includes ‘Industrial waste disposal’
(c) Romania: ‘others’ also include accidents
(d) Netherlands: ‘others’ also include accidents
(e) Liechtenstein: ‘others’ only refer to accidents; minor accidents are not included.
(f) Lithuania: petrol stations included in ‘oil extraction’; pesticide storage installations included in ‘other hazardous substances spill sites’
(g) Germany: ‘Industrial activities’ also include accidents and ‘other’; ’Municipal waste disposal’ also include ‘Industrial waste disposal’
(k) Belgium-Flanders: ‘oil extraction and storage sites’ also include ‘oil spills sites’ several activities can occur together on 1 site (127%)
For DK, GE, LI, NL, ES and RO the category ‘Industrial activities’ was used instead of the here used ‘industrial and commercial sites’.
The main activities identified as main sources of local pollution are:
DARMENDRAIL Dominique, BRGM - Environment & Process Division,www.brgm.fr
European Environment Agency
Management of contaminated sites in Western Europe – June 2000
European Environment Agency
Useful Web Links
Ad Hoc International Working Group on Contaminated Land
CARACAS: Concerted Action on Risk Assessment for Contaminated Sites in the European Union -(EC 4Th Framework Research Program)
CLARINET: Contaminated Land Reclamation Network for Environmental Technologies in Europe -(EC 5Th Framework Research Program)
List of Key Technical Terms
The potential of a risk source to cause an adverse effect(s)/event(s)
The identification of a risk source (s) capable of causing adverse effect(s)/event(s) to humans or the environment, together with a qualitative description of the nature of these effect(s)/event(s)
Agent, Medium, commercial/industrial process, procedure or site with the potential to cause an adverse effect/event(s)