Guidelines for Environmental Risk Assessment and Management
[This document refers, in a number of instances, to the then Department of the Environment, Transport and the Regions (DETR). The text of this document has not been updated since the transfer of environmental protection functions to Defra.]
Chapter 9
Monitoring
This chapter outlines the main points to consider in monitoring, but it is not the purpose of these guidelines to provide detailed advice. Monitoring plays a central role in environmental risk assessment and management and is undertaken to gain continuous or periodic information about aspects of an intention before it starts, during its lifetime and after its completion. Information from monitoring programmes is integrated into environmental risk assessment and management in various ways:
- as the baseline against which to compare actual and predicted impacts;
- as an input to models, forecasts and quantification stages;
- to provide information to feed back into the risk assessment in an iterative process;
- to confirm that risk assessments and management options are meeting their desired aims; and
- as an alert mechanism if adverse impacts are found.
Baseline information
Describing the situation before the intention is one of the first steps in the problem formulation stage (Chapter 4). Where possible, this baseline should be derived from sampling and monitoring in the immediate vicinity of the intention. Where this is not possible (for example, where the operation being assessed has already commenced) the baseline can be derived from a reference area unaffected by the intention. In this case, the reference area should be similar in physical, environmental and ecological character. In some situations it may be useful to use such a reference area as a control, in which case baseline monitoring will be needed both at the reference area and in the immediate vicinity of the intention.
The baseline is not static and may change over time within a given area. Impacts that may appear at first to be attributable to the intention may in fact be the result of natural variation or other indirect changes (Section 7.3). It is also important to consider the effect that socio-demographic changes can have on the significance of a risk.
A related issue is distinguishing effects of previous or nearby activities from effects stemming from the intention. Only with a well-defined baseline can such a distinction be made. For instance, the death of vegetation near a newly built factory on a former gas works site could not easily be attributable to either the new factory or the previous site use without baseline monitoring.
Models and forecasts
Monitoring programmes can provide valuable data for modelling and forecasting the environmental effects of an intention. The information need not be new (ie gathered specifically for the purpose). For example, actuarial data are used to help predict when components in a system will fail (Section 6.2). The more specific the information is to the intention, the more certainty can be placed in predictions or models based on it.
While monitoring can help predict trends, it is less useful where events are rare or where an event is not easily distinguishable from the baseline.
Audit and alert
Because of the inherent uncertainty in environmental risk assessment, some forecasts may not be on target. Monitoring thus becomes a useful tool for either confirming or contradicting forecasts. For example, a risk assessment of a new shopping centre may predict no significant adverse effects on local air quality from changes in traffic patterns, but monitoring may show air quality impacts of more significance than predicted. There are two courses of action to take when this happens: first, to instigate management options to address the impacts, and second, to use the findings to modify and improve current and subsequent risk assessments. This highlights the iterative nature of the risk assessment framework described in Chapter 2.
Monitoring can also play a role in retrospective assessment. This approach is similar to human epidemiology and is sometimes termed ecoepidemiology. For example, the cause of a decline in a lake's fish stocks may not immediately be apparent. Using ecoepidemiology, the reproductive success, contaminant levels, fry survival and other parameters might be used to infer that the decline was caused by contamination.
9.2 What to monitor
It is rare to be able to monitor every parameter relating to the intention. It is therefore important to tailor a monitoring programme to the particular situation; it should be designed with specific goals and questions in mind in order to increase its usefulness and cost-effectiveness.
Problem formulation
Deciding what to monitor will to a great extent depend on the intention in question and on the outcome of the problem formulation stage (Chapter 4). The problem formulation should have identified the most important risk components associated with a given intention and it is these components that require monitoring. The problem formulation will also define the temporal and spatial scale of the risk assessment and thereby define the monitoring boundaries.
Controlling factors
Hazardous events are often subject to factors controlling their timing, intensity and duration (Section 4.5). These factors are an ideal focus for a monitoring programme. For example, it will be difficult to predict a flood without monitoring rainfall and river flows.
Expertise and knowledge
A prerequisite for the design of an effective environmental monitoring programme is a good understanding of the local ecosystem and the possible effects of the intention. This understanding underlies the identification of the possible risks of the intention. In addition, projects or policies can have effects that extend beyond local ecosystems and have regional, national or even global significance, such as acid rain or global warming.
Two key considerations to note when choosing measurement parameters are natural variability and sensitivity to risk exposures. For instance, a simple approach in ecosystem monitoring is observing changes in population levels of important, relevant species. If there is no change in population then there is deemed to be no significant effect. Such an approach is not sufficiently refined, however, to detect sub-lethal effects, and for this purpose, more descriptive measures of status of the environment are employed, such as reproductive rates and bioconcentration levels.
9.3 Designing the monitoring programme
Having decided what information is needed for assessing and managing the risk, and from this deciding what to monitor, the next stage is to design the monitoring programme. Normally, specialist advice will be needed in order to ensure that the appropriate parts of the environment (air, water, soil, biota) are monitored and that the programme delivers the information required at an optimum cost. Preliminary surveys to obtain data on which to base the design may be needed. A poorly designed monitoring programme will almost certainly result in considerable waste of time and effort and, worse, fail to produce the information required to assess or manage the risk.
Where to sample
Sampling locations will normally be located either close to the risk being assessed, or in an appropriate reference area (Section 9.1). The precise location of the sampling point within that area can be of critical importance. For example, when sampling a river for water quality measurements, it is important to know whether or not water quality is homogeneous across the river at the sampling point. If it is not, a decision will need to be made about where within the cross-section of the river the best information about environmental impact will be obtained.
When to sample
Sampling frequency will depend on the precision with which information is required, the natural variability of the receiving environment and the nature of the hazard. Statistical analysis of these factors will indicate the minimum sampling frequency necessary to deliver the required information. A lower sampling frequency will reduce the monitoring programme costs, but at the expense of reduced precision. A judgement will often be needed about the costs and benefits of improved precision.
Sampling pattern
If the feature being monitored is intermittent (for example, a non-continuous discharge to air) it will be necessary to determine the most useful sampling pattern. This will not always be a regular pattern. For example, sampling air quality at the same time of day, on the same day each week will only provide limited information on general air quality. If this happens to coincide with a regular discharge then the monitoring programme will provide information about the instantaneous effect of the discharge on air quality. If the long-term or average impact of the discharge on air quality is required, then a different sampling pattern will be necessary (for example, a randomised or regularly rotating programme).
Sampling technique
The way in which the sample is taken, the type of material in which it is collected and stored, and the length of time between sampling and any further investigation (for example chemical analysis) can all substantially influence the validity of the derived data. Factors to be considered include the dangers of cross-contamination from the sampling container, disturbance of the sample by inappropriate handling or storage, and, when sampling birds, fish or mammals, the need to avoid inflicting unnecessary suffering.
9.4 Interpreting and dealing with monitoring data
Even simple monitoring and sampling programmes produce large amounts of raw data that, to be of most value to risk assessment and management, must be interpreted and processed appropriately. The methods used for this will depend on the type of data gathered and their proposed use. Data presentation can range from simple graphs, figures or tables, to more complex methods using mapping techniques or Geographic Information Systems.
The various parameters in a monitoring programme are sometimes aggregated or represented as an index (such as 'ecosystem health'), or expressed in terms of one parameter that integrates other factors. For example, the parameter 'species abundance' can reflect anthropogenic factors such as chemical contamination, physical disturbance and harvesting rates as well as natural variables. However, indices such as ecosystem health may not be transparent or comprehensible to either the public or decision-makers.
Wherever possible, the key stakeholders and the general public should have access to both the raw and the processed data, making sure that the key uncertainties and assumptions made are duly described.
9.5 Further information
Key references
Calow P, ed (1993/1994) Handbook of Ecotoxicology, Vols. 1
and 2, London, UK, Blackwell Scientific Publications
This is a well-structured and clear account of ecotoxicology; of particular
interest is Chapter 20 in Volume 1 (Hopkin) focusing on monitoring, its
driving forces, the main approaches, and recommendations on how to ensure
it meets the needs of risk management and decision-making.
Calow P (1998) Handbook of Environmental Risk Assessment and Management,
Oxford, UK, Blackwell Science
A comprehensive treatment of the basic principles of environmental
risk assessment and management. Various chapters discuss monitoring, auditing
and surveillance.
Keith LH (1991) Environmental Sampling and Analysis: a practical
guide, Michigan, USA, Lewis Publishers
Covers the planning, sampling, analysis and reporting of environmental
monitoring programmes.
Lave LB & Upton AC, eds (1987) Toxic Chemicals, Health and
the Environment, Baltimore, USA, Johns Hopkins University Press
A useful collection of papers on environmental monitoring, from
measuring chemicals in the environment to the clean-up of contaminated
sites.
Peakall D (1992) Animal Biomarkers as Pollution Indicators,
London, UK, Chapman & Hall
A thorough review and discussion of the use of biomarkers (particularly
animals) in ecotoxicology and pollution monitoring, including their role
in studies at the individual level to the level of the ecosystem.
Schnoor JL (1996) Environmental Modeling: Fate and Transport of
Pollutants in Water, Air and Soil, New York, USA, John Wiley &
Sons
Addresses key questions about fate, transport and long-term effects
of chemical pollutants in the environment.
Walker CH, Hopkin SP, Sibly RM & Peakall DB (1996) Principles
of Ecotoxicology, London, UK, Taylor & Francis
An excellent textbook covering the fundamentals of ecotoxicology,
including fate and behaviour of chemicals, use of biomarkers, toxicity
testing and discussions on ecotoxicological impacts from the level of
the individual through to the ecosystem, including case studies.
Electronic information sources
Bath Information Data Services internet site - www.bids.ac.uk/
British Geological Survey internet site - www.bgs.ac.uk/
Centre for Ecology and Hydrology internet site - www.ceh-nerc.ac.uk/
Countryside Agency internet site - www.countryside.gov.uk/
DETR Environmental Protection internet site - www.defra.gov.uk/environment/
English Nature internet site - www.english-nature.org.uk/
Manchester Metropolitan University Atmospheric Research and Information Centre internet site - www.doc.mmu.ac.uk/aric/arichome.html
Natural Environment Research Council internet site - www.nerc.ac.uk/
UK National Air Quality Information Archive internet site - www.aeat.co.uk/netcen/airqual/
World Conservation Monitoring Centre internet site - www.unep-wcmc.org/
WRc (Water Research Centre) internet site - www.wrcplc.co.uk/
Key periodicals
Agriculture, Ecosystems and the Environment
Clean Air
Conservation Biology
Environmental Pollution
Environmental Science and Technology
Environmental Toxicology and Chemistry
Global Climate Change Digest
Ground Water Monitoring and Remediation
Haznews
Journal of the Air and Waste Management Association
Journal of the Chartered Institution of Water and Environmental Management
Marine Pollution Bulletin
Water Environment Research
Water Research
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Page last modified:
8 October 2003
Page published: 2 August 2000