The geophysical survey area are a large scale harmful metal soil polluted site.which is about 5000 square meters.
The field testing is mainly as the ERT resistivity method and induction electromagnetism method. Which also combined with the existing drilling and excavation XRF sieve test data, verify the mode field of soil pollution characteristics and depth of local electric change trend, and the specific geophysical images depicting underground pollution and formation condition, and accurate assessment of soil pollution depth and high concentration the soil heavy metal pollution in the region, providing reliable information for future construction.
Metho | Length∕area | Intended depth | Arrary types∕ Measurin | Spacing Between | Spacing | Remarks |
EM | 5000 Square meter | 2m | More than 20,000point | 5m | 0.1～0.3m | Rapid detection of obviously pollution range |
ERT | 917.5Meter | 6m | 4PVES | 10～20m | 0.5～1m | Detecting the depth and scope of soil pollution |
The site is equipped with a systematic grid layout, and the grid spacing is 10~20 meters. A total of 12 survey lines, CX-1 ~ CX-12, have been planned.The distance between electrodes is 0.5 to 1 meters, 917.5 meters total length . The content of heavy metals in the site is high, including arsenic, lead, cadmium, copper and zinc, etc., and the low resistivity characteristics of contaminated soil are used to confirm the depth of soil pollution. At the same time, compared with the existing drilling data, the electrical characteristics of waste burial are evaluated.
As the detection results shown that the overall formation electrical can roughly be divided into three layers from top to bottom, the resistivity showed low resistivity (the first layer), the resistivity (second layer), high resistivity (third layer) electrical change trend, which has started to rise with the depth change.
2D Interpreted imaging(1)
The first layer is shown as heavy metal contaminated soil, has obvious characteristics of low resistivity, by analyzing the most contaminated soil resistivity range is about 10 ~ 80 Ohm-m, then falls on the resistivity of red to yellow green, analysis of average depth of about 1.2 to 1.8 meters.
2D Interpreted imaging(2)
The second layer is presume slightly pollution soil and normal strata junction formation, has obvious characteristics of resistivity of middle value, through the analysis of resistivity ranges about 100 ~ 150 Ohm-m, the resistivity levels fall in green interval, analysis of average depth of about 1.5 to 2.2 meters.
The third layer is the normal sandy land layer , has obvious characteristic of high resistivity, the resistivity analysis range is about 150 ~ 600 Ohm-m, the resistivity levels fall in blue interval, analysis the average depth of about more than 1.8 meters.
2D Interpreted imaging(3)
Note: the distribution of obviously soil below 80 Ohm-m 3D combine imaging(1)
Note: the distribution of high trend contaminated soil below 50 Ohm-m 3D combine imaging(2)
Heavily metal contaminated soil at experimental area has obvious low resistivity characteristics. High concentration heavy metal soil has strong magnetic susceptibility and high conductivity characteristics. The survey results show that heavy metal pollution is present on the whole site, and the depth of site pollution is about 1.2 to 1.8 meters.
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