Hỗ trợ mẫu và các vấn đề quy mô liên quan Lấy mẫu và lấy mẫu * Thiết kế Không xác định đầy đủ [mẫu] hỗ trợ từ lâu đã là nguồn gốc của sự nhầm lẫn trong đặc tính trang web và khắc phục hậu quả bởi vì nguy cơ do tiếp xúc lâu dài có thể liên quan đến việc dày đặc hỗ trợ hàng trăm hoặc hàng ngàn mét vuông, loại bỏ bởi loader backhoe hoặc phía trước cuối cùng có thể liên quan đến khắc phục tối thiểu đơn vị của 5 hoặc 10 m2 và các phép đo mẫu có thể được. | C H A P T E R 1 Sample Support and Related Scale Issues in Sampling and Sampling Design Failure to adequately define sample support has long been a source of confusion in site characterization and remediation because risk due to long-term exposure may involve areal supports of hundreds or thousands of square meters removal by backhoe or front-end loader may involve minimum remediation units of 5 or 10 m2 and sample measurements may be taken on soil cores only a few centimeters in diameter. Englund and Heravi 1994 The importance of this observation cannot be overstated. It should be intuitive that a decision regarding the average contaminant concentration over one-half an acre could not be well made from a single kilogram sample of soil taken at a randomly chosen location within the plot. Obviously a much more sound decisionmaking basis is to average the contaminant concentration results from a number of 1-kg samples taken from the plot. This of course assumes that the design of the sampling plan and the assay of the individual physical samples truly retain the support intended by the sampling design. It will be seen in the examples that follow that this may not be the case. Olea 1991 offers this following formal definition of support An n-dimensional volume within which linear average values of a regionalized variable may be computed. The complete specification of the support includes the geometrical shape size and orientation of the volume. The support can be as small as a point or as large as the entire field. A change in any characteristic of the support defines a new regionalized variable. Changes in the regionalized variable resulting from alterations in the support can sometimes be related analytically. While the reader contemplates this formal definition the concept of sample support becomes more intuitive by attempting to discern precisely how the result of the sample assay relates to the quantity required for decision making. This includes reviewing all of
