Portable XRF data screening method for heavy metal contaminated soil

A portable XRF data screening method for heavy metal contaminated soil, comprising the following steps:

• (1) laboratory test:
• testing a soil sample in a laboratory to obtain a laboratory test value, which is identified as a true value and denoted by LAB;
• (2) XRF test:
• calibrating an X-ray fluorescence spectrometer with a calibrating sample, and testing pretreated soil with the calibrated X-ray fluorescence spectrometer to obtain an X-ray fluorescence spectrometer test value, which is identified as an estimated value and denoted by XRF;
• and
• (3) calculation of a recheck interval:
• dividing test data into four areas by a contaminant screening value Xc as a horizontal line and a correlation-derived site screening value as a vertical line;
• calculating a recheck interval with a number of samples n, a standard value μ and a sample standard deviation S, specifically comprising:
• {circle around (1)} determining a significant level α;
• {circle around (2)} calculating the sample standard deviation S;
• {circle around (3)} determining a critical value C=tα(n−1) according to the degree of freedom df=n−1 and α;
• and
• {circle around (4)} calculating a lower recheck interval limit μ−C×S/√{square root over (n)}, and an upper recheck interval limit μ+C×S/√{square root over (n)}, thus obtaining a recheck interval [μ−C×S/√{square root over (n)}, μ+C×S/√{square root over (n)}];
• determining, according to the situation that the sample falls into the four areas in the recheck interval, whether or not to further recheck the sample.