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Introduction to environmental analysis - Reeve R.

Reeve R. Introduction to environmental analysis - Wiley publishing , 2002. - 312 p.
ISBN 0-471-49295-7
Download (direct link): introductiontoenvironmental2002.pdf
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Introduction to Environmental Analysis
possible that the soil had been contaminated with chlorinated solvents from the previous industrial activities.
DQ 5.10
Look at the UK definition of contaminated land given above in Section 5.1. What effect does this definition have on likely analytical schemes and subsequent data interpretation?
Answer
The definition includes the phrase ‘actual and potential hazard’. Compounds or ions may be present in such low concentrations that they do not present a hazard unless they are known to bioconcentrate (see Section 2.3.1 earlier). Some estimation of the total quantity of the contaminant on the site is also necessary.
The physical and chemical forms of the materials (i.e. speciation) will need to be determined as they will affect whether a material will be released under given environmental conditions. Consider the difference in the toxicities of chromium (iii) and chromium (vi) discussed earlier in Section 4.3.7.
The definition is based on ‘hazard to health’. Consideration has to be taken of the potential migration of the compounds and the location of target organisms or vulnerable sections of the environment. Sampling and analyses should then be concentrated on this route (see Section 2.6 above).
The interpretation of the data with respect to whether there is a ‘actual or potential hazard to health’ depends to a large extent on the end use of the land. The same analytical data can be interpreted in different ways according to its future use!
5.5.1 Steps in the Investigation of Contaminated Land
The first stage in sampling contaminated land is background paper research into the history of the site to decide any potential problems. A simple walk-over site inspection could then be made for visible signs of pollution. This can then be used to decide what analysis may be necessary and to determine a sampling strategy.
DQ 5.11
Why is the determination of sampling sites a particular problem for contaminated land?
Analysis of Land, Solids and Waste
153
Answer
It may not be obvious how to define the area in which contamination has occurred. A small number of sampling sites may, in fact, miss areas of pollution. Sampling can also often be complicated by the variety of solids which may make up the ‘land’ on an old industrial site. This could be soil, sand, shale, brick, remnants of concrete buildings and other industrial waste.
Particular care should be taken where there is likely to be small areas of relatively high concentrations of contamination (‘hot spots’) that the sampling scheme will be the most suitable. It is quite possible that contamination from a single source on to sloping land is in the form of a ribbon from the source. If a regular grid sampling strategy is used (see Table 5.1 above), a herringbone-type grid is sometimes suggested as this would be less likely to miss ribbon contamination than the common square-grid pattern (Figure 5.4).
At this stage, simple surface tests could be performed, sampling with trowels or with one of the soil samplers shown earlier in Figure 5.2. You should remember the potentially corrosive nature of many industrial contaminants and all tools should be either PTFE-coated or made of stainless steel.
A number of field monitors have been developed for rapid site assessment to lessen the need for expensive laboratory analysis. These include the following:
(i) Immunoassay test kits. Did you notice when we were looking at water immunoassay kits (see Section 4.2.5 above) that many were for industrial contaminants? Much of the development for these kits has been for contaminated land analysis. The kits include simple apparatus to extract the contaminant from the soil into solution. Immunoassay of the extract then follows.
(ii) Portable X-ray fluorescence (XRF) spectrometers. XRF is a method for elemental analysis which has the great advantage that it can directly analyse

X X X X

X X
X X X X
Square-grid sampling - hot spots may be located
Square-grid sampling -ribbon contamination may be missed
Herringbone-pattern sampling - better for ribbon contamination
X
Figure 5.4 Some examples of sampling strategies employed for localized contamination.
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Introduction to Environmental Analysis
solids as well as liquids. Within chemical analytical laboratories, it has been used much less than atomic techniques (see Section 4.3.3 above) due to lower accuracy, often attributable to strong matrix effects. Simplified instruments can be made portable and give readings in the mg kg-1 concentration range. Lead analysis is a typical application. The theory and instrumentation of XRF will be described later in Section 7.4.1.
(iii) Monitors for specific groups of compounds. These are based on spectroscopic properties which can identify the groups without separation. UV fluorescence monitors can be used for PAHs (c.f. Section 4.2.4) and infrared absorption for hydrocarbons (cf. Section 4.2.6). Some other uses of IR for environmental analysis will be discussed later in Chapter 6.
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