Field study design

Untreated (control) soil is collected to determine the presence of substances that may interfere with the measurement of target analytes. Control soil is also necessary for analytical recovery determinations made using laboratory-fortified samples. Thus, basic field study design divides the test area into one or more treated plots and an untreated control plot. Unlike the treated plots, the untreated control is typically not replicated but must be sufficiently large to provide soil for characterization, analytical method validation, and quality control. To prevent spray drift on to the control area and other potential forms of contamination, the control area is positioned > 15 m away and upwind of the treated plot, relative to prevailing wind patterns. 

In an attempt to provide this focus, forty-seven active receptor model users from government, university, consulting and industry met for 2 1/2 days in February 1980 it. They addressed the models and the information required to use them in six separate task forces 1) Chemical Element Balance Receptor Models, 2) Multivariate Receptor Models, 3) Microscopic Identification Receptor Models, 4) Field Study Design and Data Management, 5) Source Characterization, and 6) Analytical Methods. The objectives of these interrelated task forces were to ... 

The measurements required for the present receptor models Include particulate matter composition, size and variability for both source and receptor. Obtaining these data requires attention to field study design and data management, source characterization, and analytical methods. 

Cost will be the primary controlling factor In the experimental design In essentially all cases. The cost of obtaining the entire population of possible measurements Is prohibitive. The field study design must select a subset which Is representative of the population within definable confidence limits and which can be obtained within the constraints of existing resources. 

Future development efforts in field study design and data management should 1) develop methodologies for choosing sampler location, sampling schedule, and sampling devices 2) measure the collection efficiency of available samplers as a function of particle size, windspeed and wind direction 3) create a series of "typical" design scenarios which can be specified for different aerosol study objectives 4) develop standardized data bases from which ambient and source information can be recovered. 

The fourth and final need is for doctmentation and education. The validation and standardization will go for naught if the practice of receptor modeling cannot be established at the state implementation plan level where it is most sorely needed. Major reviews of model applications, analytical methods, source characterization and field study design need to be prepared and communicated to those most likely to make use of them. 

The fundamental issues in field study design can be outlined by a series of simple interrogatives who, where, when, how long, how often and how many The answers to these questions require substantial prior knowledge of worker populations and working conditions, as well as the toxicological and metabolic... 

Table 1 provides a brief definition of the state factors of soil formation. A field study designed to observe the influence of one state factor on soil properties or processes is referred to as a sequence, e.g., a series of sites which have similar state factor values except climate is referred to as a climo-sequence. Similar sequences can, and have been, established to examine the effect of other state factors on soils. An excellent review of soil state factor studies is presented by Birkeland (1999). An informative set of papers discussing the impact of Jenny s state factor model on advances in pedology, geology, ecology, and related sciences is presented in Amundson et al. (1994a,b). 

Protocols must be maintained for all studies for which the QAU is responsible. In many instances field cooperators are left off of the protocol distribution list or receive only pertinent pages of the protocol. While it may not be necessary for the field personnel and their QAU to have the analytical portion of the protocol, they should at least have the title page, signature page, field study design portion, and any amendments to these sections in order to comply with the intent of 160.35(2). 

Anodic Protection On the reverse anodic scan there will be a low current region (LCB) in the passive range. The passive potential range of the LCB is generally much narrower than the passive region seen on a forward slow scan. In anodic protection (AP) work the midpoint of the LCB potential is the preferred design range. This factor was verified for sulfuric acid in our laboratory and field studies. 

Kedwards, T.J., Maund, S.J., and Chapman, PE. (1999a and 1999b). Community level analysis of ecotoxicological field studies 1 Biological Monitoring and 11 Replicated design studies. Environmental Toxicology and Chemistry 18, 149-157 and 158-166. 

Although the original additivity principle of Wagner and Traud has been an immensely useful concept with applications in numerous fields, carefully designed studies in receiit years have revealed a number of exceptions. These have been described above and are summarized in... 

The design of this fish study centered on sample collection, preservation, preparation, analysis, and QA/QC. There was no discussion of the effect of compositing on the sample population. No description was given of statistical techniques to be applied to the data for reporting results and for comparison with action levels and future data. Unfortunately, the omission of a statistical framework during planning of the field study is the rule rather than the exception in hazardous waste investigations. 

The RAC and processed commodities to be collected for each crop are listed in OPPTS 860.1000. Close attention should be paid to the definition and description of many of the commodities listed in the footnotes to Table 1. Reviewing a summary of the actual commercial processing practices for the crop may be helpful. Once the processing procedures and the agronomic practices to be simulated in the field residue trial are understood, a field study can be designed that will truly represent commercial production and processing practices. This will ensure that the study will yield useful, reliable, and accurate data to be used in the tolerance setting process. 

QA is an important aspect of any technical study. It is particularly crucial in an LSMBS, because several hundred participants, widely separated geographically, are involved. The analytical laboratories typically have standard provisions for QA inspections and reviews, and the field phase management organization is also likely to have standard provisions for QA inspection and review. Shoppers, however, are typically external to study management and analytical laboratories and, thus, are not directly covered by existing QA systems. The study design must include a means by which the field phase, i.e., sample collection and shipment by the shoppers, is made to comply with QA requirements. 

Decisions made in the design of field study data collection directly and indirectly affect analytical method development. Each sampling matrix will require specific procedures, and methods need to be developed with a view to the nature and scope of field monitoring programs that are or may be required. 

At this stage in planning, the essential study design information listed below should be determined and a written study plan (i.e., protocol) including these key study details prepared. A formal, pre-approved study plan is required for field soil dissipation studies conducted under Good Laboratory Practice (GLP). A written study plan for non-GLP studies is highly recommended since the document serves as valuable guidance for study personnel. 

Additional information regarding applicator-boom width, spray-tank capacity, and the wheelbase of any vehicle-mounted soil sampling equipment used during the study is also required to ensure that the field plot design accommodates size restrictions of field equipment. 

Size of test site B Depends on study design. The minimum area required for a typical large-plot design is about 0.25 ha Test site must allow for test design plus sufficient buffer zone around perimeter of field to protect against external disturbance For bare-soil studies, shady sites should be avoided Continued overleaf)... 

A.S. Felsot, R.G. Evans, and J.R. Ruppert, Field studies of imidacloprid distribution following application to soil through a drip irrigation system , in Terrestrial Field Dissipation Studies Design, Interpretation and Purpose, ed. E.L. Arthur, V.E. Clay, and A. Barefoot, ACS Symposium Series No. 842, American Chemical Society, Washington, DC (2003). 

---