Method for evaluating data exception degree of heavy metal content in soil
A technology for abnormal data and heavy metals, applied in measurement devices, soil material testing, instruments, etc., can solve the problems of inability to identify abnormal data in soil heavy metal content data, misjudgment in soil remediation decision making, etc., and achieve accurate and reliable soil heavy metal survey data. , avoid chance and subjectivity, save the effect of testing cost
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Embodiment 1
[0039] In the step of collecting soil samples in step 1, on the basis of GPS positioning, the soil in Beijing can be used as the detection area, and the surface soil of 0-20 cm of the sample square can be collected with stainless steel soil drills and soil knives, and no foreign soil or backfill soil should be collected. , to remove man-made pollutants. Samples were collected according to a certain sampling route and the principle of "random" multi-point mixing. The number of sample points for each sampling unit shall not be less than 5 points. The thickness, depth, and width of the soil samples taken at each point should be roughly the same; each point is randomly determined. After observing the situation in the field, randomly fix the point to avoid subjective errors and improve the representativeness of the sample. Sampling is generally carried out according to the S-shaped line , using the 5-point sampling method, the 5 sampling points are composed of 4 vertices and the c...
Embodiment 2
[0041] In step 2, after the sample is collected, the pretreatment step is carried out, and it is naturally dried indoors, ground, and passed through a 100-mesh sieve. Obtain heavy metal content data according to national testing standards and relevant analysis methods. The detection methods are shown in the table below:
[0042] Table 1 Analysis and testing methods for soil heavy metals
[0043]
[0044] Obtain the soil heavy metal content data, import the content data into the system software, and use SQLServer software to create a database to store the value of the heavy metal content of each sample detected. For the absence of a certain heavy metal element at a certain sampling point, it will not participate in the verification operation of this heavy metal element; after loading the data, you need to select the heavy metal element to be verified; you need to set the corresponding parameter information for different verification methods.
Embodiment 3
[0046] In step 3, mathematical statistics verification mainly selects outliers based on the ideas of probability theory and mathematical statistics. In theory, without human interference, soil variables should conform to normal distribution or lognormal distribution, such as The content distribution of Cr and Ni in Beijing soil obeys normal distribution, and the distribution of Cd, Cu, Pb and Zn content obeys logarithmic normal distribution. M is the mean value of the data, S is the standard deviation of the data, when setting 2 times S, M-2S to M+2S is the 95% confidence interval. In this embodiment, a confidence interval of 95% is selected. According to the confidence interval, abnormal data outside the confidence interval can be selected, and information about the abnormal value can be obtained and stored.
[0047] The background verification method mainly combines the background value of soil heavy metal content, based on the idea of probability theory and mathematical s...
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