SPADA Draft Documents

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7.2 Criteria for Selecting Soils 230 or method is being developed for deployment in a very specific region of the world, then 231 soils specific to that region should be collected. For intended uses not specific to one 232 region, Table 1 from the Organization for Economic Co-operation and Development 233 (OECD) Guideline 106 (8) provides soil characteristics covering a wide range of pH, 234 organic content, and clay content typically found in temperate geographical zones. This 235 international guideline was developed in 2000 and used by the US Environmental 236 Protection Agency (EPA) in studies concerning the mobility, distribution, and 237 degradation of chemicals in soils. Ideally, all 7 soil types from Table 1 should be 238 included in the experimental testing. If it is not possible to test all 7 types of soil, it is 239 recommended to test at least 5 soils of varying characteristics following the guidance 240 from Table 1. There may be cases in which extreme soil types (e.g., coastal soil with high 241 salt content) are required for a specific purpose. In these cases, the soils of interest should 242 be characterized and documented prior to testing, which may include additional 243 characterization tests for specific parameters of interest. As much as possible, a variety of 244 soils covering the range of the parameter of interest should be included in the 245 experimental testing. Soil selection depends on the intended use of the method or system. If an instrument

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Table 1. Guidance for selection of soil samples a

pH range (in 0.01 M CaCl 2 )

Organic carbon content (%)

Clay content (%)

Soil type

Soil texture

1 2 3

4.5-5.5

1.0-2.0 3.5-5.0 1.5-3.0

65-80 20-40 15-25

Clay

>7.5

Clay loam Silt loam

5.5-7.0

Draft Version 16

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