Research On Detection Method Of Heavy Metal Pollution In Soil Based On Ground Penetrating Radar Signal Waves

The soil which is polluted by heavy metals has become a worldwide environmental problem.The soil which is polluted by heavy metals has the characteristics of long duration,strong residual toxicity,and difficulty to recover in the short term.It not only affects the growth of plants,but also enters animals and the human body through the food chain,resulting in serious threat to human health.Although the traditional detection method has high accuracy,its detection method is complicated and the operation is cumbersome,resulting in a long detection time and secondary pollution.However,some new detection methods have not been popularized and it is difficult to meet the needs of environmental monitoring.Therefore,it is urgent to exp lore a simple、efficient、convenient、accurate and low-cost heavy metal detection method.This paper is based on the National Natural Science Foundation of China’s project: Coupling process of water movement parameters in the unsaturated zone with ground-penetrating radar signals(41372260),based on in-situ detection of indoor experiments and field sampling.The relationship between dielectric constants and the characteristics of the heavy metal pollution was studied by using different particle grading,heavy metal species,and moisture content.Based on this,the relationship between signal wave and heavy metal pollution was studied,and the concentration of heavy metal and electromagnetic wave were constructed.The eigenfunction between the amplitude properties,and the application of in situ exploration in Jiyuan city,provide theoretical basis for establishing the relationship model between heavy metal pollution concentration and electromagnetic wave amplitude properties,and the soil environmental protection as well as detection,treatment,and restoration of soil heavy metals.Pollution is of great significance.Based on a large number of experiments and theoretical explorations,this article has achieved the following main conclusions:(1)Relationship between soil medium and dielectric constantUnder non-pollution conditions,when the water content is higher than 15%,the dielectric constant in the five media of silty clay,silt,silt,fine sand and medium sand is: silty clay> silt> Silty sand> fine sand> medium sand,indicating that fine-grained soils have greater influence on dielectric properties than coarse-grained soils.(2)Relationship between moisture content,heavy metal concentration and dielectric constantWhen the water content is lower than 5%,the influence of Cd and Pb pollution on the dielectric properties of medium sand is not obvious.In silty clay and silt media,when the moisture content is higher than 20%,the Cd and Pb pollution has a significant effect on the dielectric properties of silty clay and silt media.And the higher concentration of heavy metal Cd and Pb,the more obvious the dielectric properties of silty clay,silt media;In silt,fine sand,and medium sand media,when the moisture content is higher than 15%,the Cd and Pb pollution has a significant effect on the dielectric properties of silt,fine sand,and medium sand media.And the higher concentration of heavy metal Cd and Pb,the more obvious the effect on the dielectric properties of silt,fine sand,medium sand media.When the moisture content is less than 20%,the change of heavy metal concentration has little effect on the dielectric constant of the soil sample.When the water content is higher than 20%,and the Pb and Cd concentrations are higher than 200 mg/kg and 1.3 mg/kg,respectively,the concentration has a significant effect on the dielectric constant.As the concentration of heavy metals increases,the dielectric constant shows an increasing trend.When the moisture content was close to 30%,and the Pb and Cd concentrations were higher than 200 mg/kg and 1.3 mg/kg,respectively,the dielectric constant reached the maximum value.The dielectric constant of soil is influenced by the three factors of moisture content,heavy metal pollution concentration and soil particles.When the moisture content is higher,the soil medium particles is finer,the more sensitive the dielectric constant to the change of heavy metal pollution concentration.(3)Relationship between Electromagnetic Wave Properties and Heavy Metal ConcentrationThe correlation coefficient between the rms amplitude and the mean absolute amplitude trend line is relatively high,reaching 0.7 and 0.8329.Root mean square amplitude fluctuates between 2000 and 3000 in the range of 250mg/kg to 300mg/kg.In the range of 50mg/kg to 100mg/kg,the mean absolute amplitude and mean square The root amplitude pattern is similar,the same is the concentration of 50mg/kg to 100mg/kg,the amplitude decreases.Therefore,the two electromagnetic wave properties,rms amplitude and mean absolute amplitude amplitude,are most sensitive to the response of the geological radar with changes in concentration.(4)Extract the amplitude data by using the prepared Ground Penetrating Radar electromagnetic wave attribute analysis processing software,and construct the characteristic function between the heavy metal pollution concentration and the electromagnetic wave amplitude attribute.The concentration of heavy metals was calculated by using the correlation function of signal waves of the ground radar and heavy metal pollution.After comparison,the concentration of heavy metals agrees well with the measured heavy metal concentration.Therefore,the law of the change of the average heavy metal concentration can be predicted by the law of the average absolute amplitude amplitude,providing a theoretical basis for establishing the relationship model between the heavy metal pollution concentration and the amplitude properties of the electromagnetic wave,and the soil environmental protection as well as detection,treatment and restoration of soil heavy metals.Pollution is of great significance.