Scientific and engineering improvement of environmental risk management - Environmental Deterioration and Contamination: Problems and their Management - page 396

(e.g., species diversity) or an ecotoxicological assessment be applied to a deteriorated
land or a contaminated site? Should chemical analytical methods or ecotoxicity mea-
surements dominate the tool battery used at an inherited, a newly contaminated or
an illegal waste disposal site? How should the mobility of the contaminant in the
environment and the risk of immobile contaminants unavailable to water and bio-
logical systems be characterized? How to monitor natural attenuation of a petroleum
hydrocarbon, a BTEX (benzene, toluene, ethylbenzene and xylenes) and a chlorinated
hydrocarbon underground plume, which parameters should be measured and how?
Which sampling strategy should be used and why? The questions are endless and only
a few satisfactory answers are available as of today.
The chemical model still has priority in contaminated land assessment and moni-
toring in spite of the fact that most of the sites are contaminated by mixtures and the
analytical program may miss many of the hazardous contaminants. An ecotoxicolog-
ical tool battery is rarely included and used, although it would be essential at least as
a screening and validation tool for finding hot spots and checking chemical analytical
results and performance of remediation.
We still need innovative mathematical, physico-chemical, biological and ecological
methods to be developed and integrated into problem-specific tool batteries, and the
use of data and information for early warning, monitoring and regulatory purposes. It
would be essential for an efficient environmental management to support the selection
of the optimal methodologies with regard to time and spatial scope, in situ or labo-
ratory application and uncertainty of the methods. A full and true characterization of
the methods may help to decide whether or not the assessment tool used is in harmony
with the assessment's aim and the technical and financial efforts are in proportion to
the size of risk.
Van Ree & Carlon (2003) ranked site assessment methods as field, laboratory and
screening methods according to their analytical uncertainties (sensitivity and accuracy)
as a function of spatial uncertainties (density of measurements, volume covered by one
measurement) and found the following:

- Geophysical methods are good in spatial characterization, but very poor in

analytical validity;

- The screening tools with a pattern recognition system such as electronic tongues

(on-line sensors for liquid and moisture), electronic noses (on-line sensing of
volatiles and odors) and other prescreening tools work with high analytical and
spatial uncertainty, and low selectivity;

- Immunoassays, FFD (fuel fluorescence detector to delineate hydrocarbon contami-

nation versus depth) and SMP (soil moisture probe) give better spatial information
and acceptable analytical results, and they are very good, rapid and cheap screen-
ing tools. Immunoassays are low-cost and sensitive methods, but selectivity of
the commercialized polycyclic aromatic hydrocarbons (PAHs), polychlorinated
biphenyls (PCB) and BTEX kits is generally poor. Nevertheless it is possible to
develop highly selective immunoassays based on sensors for special applications;

- Portable PID (photoionization detector), FID (flame ionization detector) and XRF

(X-ray fluorescence spectrometer) are in situ applicable rapid and inexpensive
tools, with limited accuracy and sensitivity;