Books
in black and white
Main menu
Home About us Share a book
Books
Biology Business Chemistry Computers Culture Economics Fiction Games Guide History Management Mathematical Medicine Mental Fitnes Physics Psychology Scince Sport Technics
Ads

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
Previous << 1 .. 48 49 50 51 52 53 < 54 > 55 56 57 58 59 60 .. 111 >> Next

DQ 4.28
A complete characterization of all species in a sample is a difficult and time-consuming procedure. Can you think of an alternative, and simpler, approach to species analysis to support investigations on metal transport and toxicology?
Answer
Rather than to attempt to determine each species individually, those with similar environmental transport or toxicological properties could be analysed as groups. A simple classification of metal species would be into ‘organic-solvent-soluble’ (neutral complexes and organometallic species) and ‘organic-solvent-insoluble’ (charged complexes and free ions) species. The first type would be transported in the environment and would accumulate in fatty tissues in a similar manner to neutral organic molecules (see Section 2.3 above), and the second type in a similar fashion to other ions (see Section 2.4 earlier) within the environment.
SAQ 4.5
Lengthy pretreatment techniques are often necessary with the analytical techniques described for both organic compounds and metals. Filtration, solvent extraction and chromatographic pretreatment are common methods. What could affect the precision of measurements for low concentrations of common pollutants ?
SAQ 4.6
An analytical technique for copper, lead, cadmium and zinc in water, as described in the chemical literature, involved dividing the filtered sample into five aliquots. The treatment of the aliquots (prior to ASV analysis) was as follows:
(i) Strong chemical oxidation and UV irradiation.
(ii) No pretreatment.
(iii) Weak chemical oxidation.
(iv) Passage through a chelating resin then UV irradiation.
(v) Extraction using an organic solvent, and UV irradiation of the aqueous phase.
Which species are determined in each aliquot?
134
Introduction to Environmental Analysis
Summary
Components present at trace (p,g l-1) levels can have a major affect on water quality if they can bioaccumulate in organisms or have a high degree of toxicity. These components usually fall into the two categories of organic pollutants and metal ions. Instrumental methods for the determination of the components have been discussed, along with the necessary extraction and pretreatment steps. The predominant instrumental technique for organic components is gas chromatography, whereas atomic spectrometric techniques are the most frequently used methods for metal ion analysis.
Introduction to Environmental Analysis Roger Reeve
Copyright © 2002 John Wiley & Sons Ltd ISBNs: 0-471-49294-9 (Hardback); 0-470-84578-3 (Electronic)
Chapter 5
Analysis of Land, Solids and Waste
Learning Objectives
• To understand the problems of sampling and pretreatment of solid samples prior to the analytical determination of organic compounds and metal ions.
• To apply your knowledge of these problems to the analysis of:
- plants and animals
- soil
- contaminated land
- waste and landfill disposal sites
- sediment
- sewage sludge
• To appreciate newer extraction techniques for solids and to be able to assess their role in relation to the longer-established techniques.
5.1 Introduction
This chapter introduces you to methods for the sampling and extraction of solids. These are necessary stages prior to completion of analysis by the instrumental techniques which have already been discussed for water samples. They may, in fact, be the most difficult part of the analysis. Modifications which are needed for the final analytical stage are described where these are appropriate. Be sure that you can remember the principles of the transportation of pollutants discussed in Chapter 2 as these are necessary to understand the relevance of the analysis.
136
Introduction to Environmental Analysis
DQ 5.1
Which solids do you consider to be of importance for the study of the environment? What specific analyses would be relevant?
Answer
1. Animal and plant specimens
2. Soils and contaminated land
3. Waste and landfill waste disposal sites
4. Sediments and sewage sludge
5. Atmospheric particulates
We shall consider all of these in detail in the following discussion.
1. Animal and plant specimens
These are directly of interest since the toxic effect of a compound is proportional to its concentration within the organism. The investigations would also be relevant to species further along the food chain when determining the environmental pathway of the pollutant (see Section 2.3 earlier).
Plants and animals may also be used as indicator organisms to monitor pollutants found in lower concentrations in the wider environment. As an example, heavy metal pollution in sea water is often monitored by analysis of seaweed rather than by direct analysis of the water. Remember, however, that you have to balance the advantage of the higher concentration in the living organism with the disadvantage of the more complex analytical matrix.
The effect of pollution on living organisms can sometimes also be investigated by monitoring levels of naturally occurring constituents of the organism. The effects of acid rain on trees, for instance, include a decrease in the concentration of the alkaline-earth ions in the leaves.
Previous << 1 .. 48 49 50 51 52 53 < 54 > 55 56 57 58 59 60 .. 111 >> Next