P URPOSE AND D ESIGN OF P ESTICIDE M ONITORING P ROGRAMS In general, pesticide monitoring is used to investigate and to gain knowledge that

12.2.1 P URPOSE AND D ESIGN OF P ESTICIDE M ONITORING P ROGRAMS In general, pesticide monitoring is used to investigate and to gain knowledge that

allows authorities tentatively to assess the quality of the environment, to recognize threats posed by these pollutants, and to assess whether earlier measures have been effective [18,21]. Whichever the objectives of a monitoring program may be, it is important that they are well defined before sampling takes place to select suitable sampling and analysis methods and to plan the project adequately. Another important characteristic of a monitoring program is that data produced are often used to imple- ment and regulate existing directives concerning pesticides in the environment [5].

Because of the great number of parameters (pesticide physicochemical pro- perties, climatic and environmental factors) affecting the exposure of pesticides, monitoring of a single medium will not provide sufficient information about the occurrence of pesticides in the environment. A multimedia approach that involves tracking pesticides from sources through multiple environmental media such as air, water, sediment, soil, and biota provides with data for understanding the fate and partitioning of pesticides and for the validation of environmental models [19].

A basic problem in the design of a pesticide monitoring program is that each of the earlier reasons for carrying out monitoring demands different answers to a number of questions. Thus, when a monitoring program consists of sampling, laboratory analysis, data handling, data analysis, reporting, and information exploit- ation, its design will necessarily have to include a wide range of scientific and management concepts, thus making a large and difficult task [21]. Therefore, cost- effective monitoring programs should be based on clear and well thought-out aims and objectives and should ensure, as far as possible, that the planned monitoring activities are practicable and that the objectives of the program will be met. There are

a number of practical considerations to be dealt with when designing a monitor- ing program that are generic regardless of the compartment getting monitored (Figure 12.1). For pesticide monitoring programs, some general guidelines should

Define study objectives

Identify

Site selection

possible

Data analysis

Data interpretation Identify the parties

sites

Pilot study

concerned Communication

Publications Establish management

Sampling strategy

Workshops authorities

Sample collection

Analysis

Feedback

FIGURE 12.1 Phases in planning, conducting, and reporting of a monitoring program. (From Calamari, D., et al., Evaluation of Persistence and Long Range Transport of Organic Chemicals in the Environment , G. Klecka et al., eds., SETAC, 2000.)

322 Analysis of Pesticides in Food and Environmental Samples

be taken into consideration including the clear statement of the objectives, the complete description of the area as well as the locations and frequency of sampling, and the number of the samples. The geographical limits of the area, the present and planned water or land uses, and the present and expected pesticide pollution sources should be identified. Background information of this type is of great help in planning

a representative monitoring program covering all the sources of the spatial and temporal variability of the pesticide environmental concentration. Appropriate stat- istical analysis can be used to determine probability distributions that may be used to select locations for further sampling programs and for risk assessment. The fieldwork associated with the collection and transportation of samples will also account for a substantial section of the plan of a monitoring program. The development of meaningful sampling protocols has to be planned carefully taking into account the actual procedures used in sample collection, handling, and transfer [22]. The design of a sampling should target the representativeness of the samples that is related to the number of samples and the selection of sampling stations intended within the objectives of the study. The sampling process of taking random grab samples and individually analyzing each sample is very common in environmental monitoring programs and is the optimal plan when a measurement is needed for every sample. However, the process of combining separate samples and analyzing this pooled sample is sometimes beneficial. Such composite sampling process is generally used under flow conditions and in situations where concentrations vary over time (surface water or air sampling), when samples taken from varying locations as well as when representativeness of samples taken from a single site need to be improved by reducing intersample variance effects. Composite sampling is also used to increase the amount of material available for analysis, as well as to reduce the cost of analysis. However, certain limitations must be taken into account and it should be used only when the researcher fully understands all aspects of the plan of choice [18,22].

Apart from sampling, the selection and the performance of the analytical method used for the determination of pesticides is a very critical subject. Earlier chapters of this book discuss the various methods that can be successfully applied to monitor pesticides in various environmental compartments. Another point that should be considered in the planning stage concerns the quality assurance=quality control (QA=QC) procedures to produce reliable and reproducible data. These quality issues relate to the technical aspects of both sampling and analysis. The quality of the data generated from any monitoring program is defined by two key factors: the integrity of the sample and the limitations of the analytical methodology. The QA=QC procedures should be designed to establish intralaboratory controls of sample col- lection and preparation, instrument operation, and data analysis and should be subjected to ‘‘Good Analytical Practices’’ (GAP). Laboratories should participate in a series of intercalibration exercises and chemical analysis cross-validations to avoid false positives [19,23].

As already mentioned, the whole planning of a monitoring program is aimed at the generation of reliable data but it is acknowledged that simply generating good data is not enough to meet monitoring objectives. The data must be proceeded and presented in a manner that aids understanding of the spatial and temporal patterns,

Monitoring of Pesticides in the Environment 323 taking into consideration the characteristics of the study areas, and that allows the

human impact to be understood and the consequences of management action to be predicted. Thus, different statistical approaches are usually applied to designing, adjusting, and quantifying the informational value of monitoring data [20]. However, because data are often collected at multiple locations and time points, correlation among some, if not all, observations is inevitable, making many of the statistical methods taught to be applied. Thus, in the last decade geographic information systems (GIS) and computer graphics are used that have enhanced the ability to visualize patterns in data collected in time and space [24]. In summary, statistical methods, including chemometric methods, coupled to GIS are used in recent years to display the most significant patterns in pesticide pollution [18].

Finally, one of the major parameters of the monitoring plan should be the cost of the program. A cost estimate should be prepared for the entire program, including laboratory and field activities. The major cost elements of the monitoring program include personnel cost; laboratory analysis cost; monitoring equipment costs; miscellaneous equipment costs; data analysis and reporting costs.

As a conclusion based on the earlier arguments, monitoring activities must imply

a long-term commitment and can be summarized as follows [18 –20]: (1) establish- ment of monitoring stations for different environmental compartments to fill spatio- temporal data; (2) intensive monitoring over wider areas, and continuation of existing time trend series; (3) establishment of standardized sampling and analytical methods; (4) follow-up of improved quality assurance=quality control protocols;

(5) adequate reporting of the results in the more meaningful manner; and (6) estima- tion of the monitoring program cost.